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Sample records for calculated nuclide compositions

  1. Calculated nuclide compositions and gamma-ray exposure rates for fallout from the HARRY, SMOKY, and ANNIE events

    SciTech Connect

    Hicks, H.G.

    1981-03-03

    The results of computer calculations of the nuclide composition and associated external gamma-ray exposure rates for fallout from the HARRY, SMOKY, and ANNIE events are documented. The fission product distribution is calculated for each event with the appropriate neutron spectrum and the fractions of fissions due to each fissionable material. Also calculated are the total number of microcuries per square meter and the gamma-ray exposure rates (mR/h, 1 meter above ground level) for the 152 fission products and 25 neutron-induced nuclides. The normalized data are presented in 9 Appendices. (DLS)

  2. Impact of Nuclear Data Uncertainties on Calculated Spent Fuel Nuclide Inventories and Advanced NDA Instrument Response

    DOE PAGES

    Hu, Jianwei; Gauld, Ian C.

    2014-12-01

    The U.S. Department of Energy’s Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) project is nearing the final phase of developing several advanced nondestructive assay (NDA) instruments designed to measure spent nuclear fuel assemblies for the purpose of improving nuclear safeguards. Current efforts are focusing on calibrating several of these instruments with spent fuel assemblies at two international spent fuel facilities. Modelling and simulation is expected to play an important role in predicting nuclide compositions, neutron and gamma source terms, and instrument responses in order to inform the instrument calibration procedures. As part of NGSI-SF project, this work was carried outmore » to assess the impacts of uncertainties in the nuclear data used in the calculations of spent fuel content, radiation emissions and instrument responses. Nuclear data is an essential part of nuclear fuel burnup and decay codes and nuclear transport codes. Such codes are routinely used for analysis of spent fuel and NDA safeguards instruments. Hence, the uncertainties existing in the nuclear data used in these codes affect the accuracies of such analysis. In addition, nuclear data uncertainties represent the limiting (smallest) uncertainties that can be expected from nuclear code predictions, and therefore define the highest attainable accuracy of the NDA instrument. This work studies the impacts of nuclear data uncertainties on calculated spent fuel nuclide inventories and the associated NDA instrument response. Recently developed methods within the SCALE code system are applied in this study. The Californium Interrogation with Prompt Neutron instrument was selected to illustrate the impact of these uncertainties on NDA instrument response.« less

  3. Impact of Nuclear Data Uncertainties on Calculated Spent Fuel Nuclide Inventories and Advanced NDA Instrument Response

    SciTech Connect

    Hu, Jianwei; Gauld, Ian C.

    2014-12-01

    The U.S. Department of Energy’s Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) project is nearing the final phase of developing several advanced nondestructive assay (NDA) instruments designed to measure spent nuclear fuel assemblies for the purpose of improving nuclear safeguards. Current efforts are focusing on calibrating several of these instruments with spent fuel assemblies at two international spent fuel facilities. Modelling and simulation is expected to play an important role in predicting nuclide compositions, neutron and gamma source terms, and instrument responses in order to inform the instrument calibration procedures. As part of NGSI-SF project, this work was carried out to assess the impacts of uncertainties in the nuclear data used in the calculations of spent fuel content, radiation emissions and instrument responses. Nuclear data is an essential part of nuclear fuel burnup and decay codes and nuclear transport codes. Such codes are routinely used for analysis of spent fuel and NDA safeguards instruments. Hence, the uncertainties existing in the nuclear data used in these codes affect the accuracies of such analysis. In addition, nuclear data uncertainties represent the limiting (smallest) uncertainties that can be expected from nuclear code predictions, and therefore define the highest attainable accuracy of the NDA instrument. This work studies the impacts of nuclear data uncertainties on calculated spent fuel nuclide inventories and the associated NDA instrument response. Recently developed methods within the SCALE code system are applied in this study. The Californium Interrogation with Prompt Neutron instrument was selected to illustrate the impact of these uncertainties on NDA instrument response.

  4. TOF-Bρ mass measurements of very exotic nuclides for astrophysical calculations at the NSCL

    NASA Astrophysics Data System (ADS)

    Matoš, M.; Estrade, A.; Amthor, M.; Aprahamian, A.; Bazin, D.; Becerril, A.; Elliot, T.; Galaviz, D.; Gade, A.; Gupta, S.; Lorusso, G.; Montes, F.; Pereira, J.; Portillo, M.; Rogers, A. M.; Schatz, H.; Shapira, D.; Smith, E.; Stolz, A.; Wallace, M.

    2008-01-01

    Atomic masses play a crucial role in many nuclear astrophysics calculations. The lack of experimental values for relevant exotic nuclides triggered a rapid development of new mass measurement devices around the world. The time-of-flight (TOF) mass measurements offer a complementary technique to the most precise one, Penning trap measurements (Blaum 2006 Phys. Rep. 425 1), the latter being limited by the rate and half-lives of the ions of interest. The NSCL facility provides a well-suited infrastructure for the TOF mass measurements of very exotic nuclei. At this facility, we have recently implemented a TOF-Bρ technique and performed mass measurements of neutron-rich nuclides in the Fe region, important for r-process calculations and for calculations of processes occurring in the crust of accreting neutron stars.

  5. On the calculation of activity concentrations and nuclide ratios from measurements of atmospheric radioactivity.

    PubMed

    Axelsson, A; Ringbom, A

    2014-09-01

    Motivated by the need for consistent use of concepts central to the reporting of results from measurements of atmospheric radioactivity, we discuss some properties of the methods commonly used. Different expressions for decay correction of the activity concentration for parent-daughter decay pairs are presented, and it is suggested that this correction should be performed assuming parent-daughter ingrowth in the sample during the entire measurement process. We note that, as has already been suggested by others, activities rather than activity concentrations should be used when nuclide ratios are calculated. In addition, expressions that can be used to transform activity concentrations to activity ratios are presented. Finally we note that statistical uncertainties for nuclide ratios can be properly calculated using the exact solution to the problem of confidence intervals for a ratio of two jointly normally distributed variables, the so-called Fieller׳s theorem. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Workshop on Cosmogenic Nuclides

    NASA Technical Reports Server (NTRS)

    Reedy, R. C. (Editor); Englert, P. (Editor)

    1986-01-01

    Abstracts of papers presented at the Workshop on Cosmogenic Nuclides are compiled. The major topic areas covered include: new techniques for measuring nuclides such as tandem accelerator and resonance mass spectrometry; solar modulation of cosmic rays; pre-irradiation histories of extraterrestrial materials; terrestrial studies; simulations and cross sections; nuclide production rate calculations; and meteoritic nuclides.

  7. TOF Mass Measurements of Very Exotic Nuclides: an Input for Astrophysical Calculations

    NASA Astrophysics Data System (ADS)

    Matoš, M.; Estrade, A.; Amthor, M.; Bazin, D.; Becerril, A.; Elliot, T.; Galaviz, D.; Gade, A.; Lorusso, G.; Montes, F.; Pereira, J.; Portillo, M.; Rogers, A. M.; Schatz, H.; Stolz, A.; Aprahamian, A.; Shapira, D.; Smith, E.; Gupta, S.; Wallace, M.

    2007-10-01

    Atomic masses play a crucial role in many nuclear astrophysics calculations. Very exotic nuclei can be accessed by time-of- flight techniques at radioactive beam facilities. The NSCL facility provides a well-suited infrastructure for TOF mass measurements of very exotic nuclei. At this facility, we have recently implemented a TOF-Bρ technique and performed mass measurements of neutron-rich nuclides in the Fe region, important for calculations of the r-process and processes occurring in the crust of accreting neutron stars. Description of the TOF technique, results and future plans related to nuclear astrophysics will be presented.

  8. The CAIRN method: automated, reproducible calculation of catchment-averaged denudation rates from cosmogenic nuclide concentrations

    NASA Astrophysics Data System (ADS)

    Marius Mudd, Simon; Harel, Marie-Alice; Hurst, Martin D.; Grieve, Stuart W. D.; Marrero, Shasta M.

    2016-08-01

    We report a new program for calculating catchment-averaged denudation rates from cosmogenic nuclide concentrations. The method (Catchment-Averaged denudatIon Rates from cosmogenic Nuclides: CAIRN) bundles previously reported production scaling and topographic shielding algorithms. In addition, it calculates production and shielding on a pixel-by-pixel basis. We explore the effect of sampling frequency across both azimuth (Δθ) and altitude (Δϕ) angles for topographic shielding and show that in high relief terrain a relatively high sampling frequency is required, with a good balance achieved between accuracy and computational expense at Δθ = 8° and Δϕ = 5°. CAIRN includes both internal and external uncertainty analysis, and is packaged in freely available software in order to facilitate easily reproducible denudation rate estimates. CAIRN calculates denudation rates but also automates catchment averaging of shielding and production, and thus can be used to provide reproducible input parameters for the CRONUS family of online calculators.

  9. CosmoCalc: An Excel add-in for cosmogenic nuclide calculations

    NASA Astrophysics Data System (ADS)

    Vermeesch, Pieter

    2007-08-01

    As dating methods using Terrestrial Cosmogenic Nuclides (TCN) become more popular, the need arises for a general-purpose and easy-to-use data reduction software. The CosmoCalc Excel add-in calculates TCN production rate scaling factors (using Lal, Stone, Dunai, and Desilets methods); topographic, snow, and self-shielding factors; and exposure ages, erosion rates, and burial ages and visualizes the results on banana-style plots. It uses an internally consistent TCN production equation that is based on the quadruple exponential approach of Granger and Smith (2000). CosmoCalc was designed to be as user-friendly as possible. Although the user interface is extremely simple, the program is also very flexible, and nearly all default parameter values can be changed. To facilitate the comparison of different scaling factors, a set of converter tools is provided, allowing the user to easily convert cut-off rigidities to magnetic inclinations, elevations to atmospheric depths, and so forth. Because it is important to use a consistent set of scaling factors for the sample measurements and the production rate calibration sites, CosmoCalc defines the production rates implicitly, as a function of the original TCN concentrations of the calibration site. The program is best suited for 10Be, 26Al, 3He, and 21Ne calculations, although basic functionality for 36Cl and 14C is also provided. CosmoCalc can be downloaded along with a set of test data from http://cosmocalc.googlepages.com.

  10. Calculating Subsurface Nucleonic Production of Noble Gas Nuclides: Implications on Crustal and Mantle K, Th, U Abundances

    NASA Astrophysics Data System (ADS)

    Sramek, O.; McDonough, W. F.; Mukhopadhyay, S.; Stevens, L.; Siegel, J.

    2013-12-01

    While atmospheric concentration of some noble gas nuclides is controlled by their cosmogenic production (e.g., 39Ar), nucleonic production dominates in subsurface environments. Nucleogenic production rates, which involve alpha-induced reactions, depend on Th and U abundances in the source rock. Production rates of 39Ar and 40Ar scale with K abundance in the source. Consequently, observed isotopic ratio of noble gas in crustal fluids and mantle-derived lavas can be compared to calculated predictions in order to constrain heat producing element abundances in the source rock. In particular, 39Ar/40Ar, 39Ar/21Ne, and 40Ar/21Ne inform us about U+Th abundance, K abundance, and K/U ratio. We calculate subsurface production rates for these nuclides for various assumed rock compositions. A discrepancy in existing evaluations of 39Ar production rates is noted. While Mei et al. (2010) predict a production rate of 5 atoms of 39Ar per kg per year for a K=2 %, Th=5 ppm, U=2 ppm (by weight) rock, Yokochi et al. (2012) evaluate 39Ar production rate, in number of atoms / (kg yr), at 24, and Yokochi et al. (2013) results range between 50-80. Efforts are underway to understand these differences. Experimental methods of 39Ar counting have advanced significantly in recent years, a development driven to large extent by the needs of experimental particle physics community in their search for dark matter using argon-based WIMP detectors. Measurement techniques now allow determination of 39Ar/40Ar ratios in crustal rocks and are approaching the detectability of 39Ar/40Ar ratio predicted for a mantle source. We discuss how the noble gas ratio measurements can be harnessed to gain insight into source rock's abundances of heat producing elements including mantle K/U ratio. Mei, D.-M. et al., 2010. Phys. Rev. C 81, 055802, doi:10.1103/PhysRevC.81.055802 Yokochi, R. et al., 2012. Geochim. Cosmochim. Acta 88, 19-26, doi:10.1016/j.gca.2012.04.034 Yokochi, R. et al., 2013. Chem. Geol. 339, 43

  11. Discrete beta dose kernel matrices for nuclides applied in targeted radionuclide therapy (TRT) calculated with MCNP5

    SciTech Connect

    Reiner, Dora; Blaickner, Matthias; Rattay, Frank

    2009-11-15

    Purpose: Radiopharmaceuticals administered in targeted radionuclide therapy (TRT) rely to a great extent not only on beta-emitting nuclides but also on emitters of monoenergetic electrons. Recent advances like combined PET/CT devices, the consequential coregistration of both data, the concept of using beta couples for diagnosis and therapy, respectively, as well as the development of voxel models offer a great potential for developing TRT dose calculation systems similar to those available for external beam treatment planning. The deterministic algorithms in question for this task are based on the convolution of three-dimensional matrices, one representing the activity distribution and the other the dose point kernel. This study aims to report on three-dimensional kernel matrices for various nuclides used in TRT. Methods: The Monte Carlo code MCNP5 was used to calculate discrete dose kernels of beta particles including the contributions from their respective secondary radiation in soft tissue for the following nuclides: {sup 32}P, {sup 33}P, {sup 67}Cu, {sup 89}Sr, {sup 90}Y, {sup 103}Rh{sup m}, {sup 131}I, {sup 177}Lu, {sup 186}Re, and {sup 188}Re. For each nuclide a kernel cube of 10x10x10 mm{sup 3} was calculated, the dimensions of a voxel being 1 mm{sup 3}. Additional kernels with voxel sizes of 3x3x3 mm{sup 3} were simulated. Results: Comparison with the S-value data regarding {sup 32}P, {sup 89}Sr, {sup 90}Y, and {sup 131}I of the MIRD committee which were calculated with the EGS4 code showed a very good agreement, the secondary particle transport of {sup 90}Y being the only exception. Documented analytical kernels on the other side show deviations very close and very far to the source. Conclusions: The good accordance with the only discrete dose kernels published up to date justifies the method chosen. Together with the additional six nuclides, this report provides a considerable database for three-dimensional kernel matrices with regard to beta

  12. Calculations of cosmogenic nuclide production rates in the Earth's atmosphere and their inventories

    NASA Technical Reports Server (NTRS)

    Obrien, K.

    1986-01-01

    The production rates of cosmogenic isotopes in the Earth's atmosphere and their resulting terrestrial abundances have been calculated, taking into account both geomagnetic and solar-modulatory effects. The local interstellar flux was assumed to be that of Garcia-Munoz, et al. Solar modulation was accounted for using the heliocentric potential model and expressed in terms of the Deep River neutron monitor count rates. The geomagnetic field was presented by vertical cutoffs calculated by Shea and Smart and the non-vertical cutoffs calculated using ANGRI. The local interstellar particle flux was first modulated using the heliocentric potential field. The modulated cosmic-ray fluxes reaching the earth's orbit then interacted with the geomagnetic field as though it were a high-pass filter. The interaction of the cosmic radiation with the Earth's atmosphere was calculated utilizing the Bolztmann transport equation. Spallation cross sections for isotope production were calculated using the formalism of Silberberg and Tsao and other cross sections were taken from standard sources. Inventories were calculated by accounting from the variation in solar modulation and geomagnetic field strength with time. Results for many isotope, including C-14, Be-7 and Be-10 are in generally good agreement with existing data. The C-14 inventory, for instance, amounts to 1.75/sq cm(e)/s, in excellent agreement with direct estimates.

  13. Nuclides Economy

    SciTech Connect

    Ivanov, Evgeny; Subbotin, Stanislav

    2007-07-01

    Traditionally the subject of discussion about the nuclear technology development is focused on the conditions that facilitate the nuclear power deployment. The main objective of this work is seeking of methodological basis for analysis of the coupling consequences of nuclear development. Nuclide economy is the term, which defines a new kind of society relations, dependent on nuclear technology development. It is rather closed to the setting of problems then to the solving of them. Last year Dr. Jonathan Tennenbaum published in Executive Intelligence Review Vol. 33 no 40 the article entitled as 'The Isotope Economy' where main interconnections for nuclear energy technologies and their infrastructure had been explained on the popular level. There he has given several answers and, therefore, just here we will try to expand this concept. We were interested by this publication because of similarity of our vision of resource base of technologies development. The main paradigm of 'Isotope economy' was expresses by Lyndon H. LaRouche: 'Instead of viewing the relevant resources of the planet as if they were a fixed totality, we must now assume responsibility of man's creating the new resources which will be more than adequate to sustain a growing world population at a constantly improved standard of physical per-capita output, and personal consumption'. We also consider the needed resources as a dynamic category. Nuclide economy and nuclide logistics both are needed for identifying of the future development of nuclear power as far we follow the holistic analysis approach 'from cave to grave'. Thus here we try to reasoning of decision making procedures and factors required for it in frame of innovative proposals development and deployment. The nuclear power development is needed in humanitarian scientific support with maximally deep consideration of all inter-disciplinary aspects of the nuclear power and nuclear technologies implementation. The main objectives for such

  14. Morphologic features and nuclide composition of infarction-associated cardiac myocyte mineralization in humans.

    PubMed Central

    Lockard, V. G.; Bloom, S.

    1991-01-01

    Low dietary Mg results in Ca loading of cardiac myocytes, which increases the likelihood of myocyte calcification in the event of acute myocardial infarction (AMI), and possibly increases myocyte vulnerability to necrosis. Bloom and Peric-Golia1 previously reported an autopsy study of cases from the Washington, D.C. area (a region with low levels of Mg in the drinking water), demonstrating AMI-associated mineralization in myocytes with histologically normal nuclei and cross striations, as well as in obviously necrotic myocytes. The authors have re-examined mineralized myocytes from the same autopsy material, using electron probe microanalysis, light microscopy, and transmission electron microscopy. Microprobe analysis identified Ca and P as the nuclides composing the inorganic phase of the mineral deposits. Ultrastructurally, all Ca deposits, regardless of size or intracellular location, were composed of aggregates of needlelike hydroxyapatite crystals. The mildest form of intracellular Ca deposition was observed as small Ca deposits limited to some mitochondria of myocytes, which demonstrated intact nuclei and regular sarcomere pattern. More advanced stages of intracellular calcification, in the form of Ca deposits associated with mitochondria, Z-band regions and nuclei, were observed in other myocytes that also retained intact nuclei and sarcomeres. Massive Ca deposits were associated with myocytes which showed morphologic features of advanced necrosis, including loss of nuclei, disruption of sarcomere structure and masses of cellular debris. These observations support the theory originally proposed by Bloom and Peric-Golia1 suggesting that Ca loading of myocytes, possibly related to Mg deficiency in humans, increased vulnerability of the myocytes to subsequent AMI-associated necrosis and dystrophic calcification. In addition, the light microscopic impression of calcification of otherwise normal myocytes is contradicted by the electron microscopic identification

  15. Work plan for improving the DARWIN2.3 depleted material balance calculation of nuclides of interest for the fuel cycle

    NASA Astrophysics Data System (ADS)

    Rizzo, Axel; Vaglio-Gaudard, Claire; Martin, Julie-Fiona; Noguère, Gilles; Eschbach, Romain

    2017-09-01

    DARWIN2.3 is the reference package used for fuel cycle applications in France. It solves the Boltzmann and Bateman equations in a coupling way, with the European JEFF-3.1.1 nuclear data library, to compute the fuel cycle values of interest. It includes both deterministic transport codes APOLLO2 (for light water reactors) and ERANOS2 (for fast reactors), and the DARWIN/PEPIN2 depletion code, each of them being developed by CEA/DEN with the support of its industrial partners. The DARWIN2.3 package has been experimentally validated for pressurized and boiling water reactors, as well as for sodium fast reactors; this experimental validation relies on the analysis of post-irradiation experiments (PIE). The DARWIN2.3 experimental validation work points out some isotopes for which the depleted concentration calculation can be improved. Some other nuclides have no available experimental validation, and their concentration calculation uncertainty is provided by the propagation of a priori nuclear data uncertainties. This paper describes the work plan of studies initiated this year to improve the accuracy of the DARWIN2.3 depleted material balance calculation concerning some nuclides of interest for the fuel cycle.

  16. Applying ISO 11929:2010 Standard to detection limit calculation in least-squares based multi-nuclide gamma-ray spectrum evaluation

    NASA Astrophysics Data System (ADS)

    Kanisch, G.

    2017-05-01

    The concepts of ISO 11929 (2010) are applied to evaluation of radionuclide activities from more complex multi-nuclide gamma-ray spectra. From net peak areas estimated by peak fitting, activities and their standard uncertainties are calculated by weighted linear least-squares method with an additional step, where uncertainties of the design matrix elements are taken into account. A numerical treatment of the standard's uncertainty function, based on ISO 11929 Annex C.5, leads to a procedure for deriving decision threshold and detection limit values. The methods shown allow resolving interferences between radionuclide activities also in case of calculating detection limits where they can improve the latter by including more than one gamma line per radionuclide. The co"mmon single nuclide weighted mean is extended to an interference-corrected (generalized) weighted mean, which, combined with the least-squares method, allows faster detection limit calculations. In addition, a new grouped uncertainty budget was inferred, which for each radionuclide gives uncertainty budgets from seven main variables, such as net count rates, peak efficiencies, gamma emission intensities and others; grouping refers to summation over lists of peaks per radionuclide.

  17. CHARACTERIZATION OF GRAPHITE SLEEVES FROM BUGEY 1 EDF PLANT FOR PERMANENT DISPOSAL--MEASUREMENT AND CALCULATION OF SCALING FACTORS FOR DIFFICULT-TO-MEASURE NUCLIDES

    SciTech Connect

    PONCET, Bernard R.

    2003-02-27

    Electricite De France's Bugey-1 reactor, with graphite moderator, was shutdown permanently in 1994. The natural uranium elements are encased in graphite sleeves to facilitate handling. 2,000 m3 of concrete containers, containing non conditioned graphite sleeves, must be characterized and conditioned before shipment to the national repository site called ''Centre de l'Aube''. The characterization work consists in quantifying Difficult-To-Measure nuclides (DTM) by the use of Scaling Factors (SF), which use Co-60 as tracer. Bugey developed an industrial method for the gamma counting of each package to perform easily and rapidly the measurement of the Co-60 content. Depending upon the DTM radionuclide, Co-60 scaling factors are determined, or by measurement on graphite samples (case of C-14, Cl-36, Ni-63, H-3), either by using a calculation technique which is based upon the impurities present in the graphite sleeves. This method is applied for the other pure beta emitters all DTM radionucli des : Ag-108m, Be-10, Ca-41, Cd-109, Cd-113m, Co-57, Cs-135, Cs-137, Eu-155, Fe-55, Gd-153, Mo-93, Nb- 93m, Nb-94, Ni-59, Pd-107, Pm-147, Sm-151, Sn-119m, Sn-121m, Sn-126, Sr-90, Tc-99, V-49 and Zr-93. Calculations use six sleeve history cases : 1 year at 50% power, 2 years at 50 % power, 3 years at 50 % power, 4 years at 50 % power, 1 year at 100 % power and 2 years at 100 % power. The DTM nuclides have been calculated from impurity concentrations for each of these six cases, and the greatest scaling factor has been kept. The calculation is based upon two impurity sets: First impurity set : a reverse activation calculation provides us with the best estimate value of impurities calculated from the measured mean gamma spectrum and from measured scaling factors. It consists in solving a system of simultaneous equations for the impurities as a function of the mean gamma radioactive spectrum and of the measured scaling factors. The concerned calculated impurities are Co, Cl, Li, Ag, Cs

  18. Predicting the production rates of cosmogenic nuclides in extraterrestrial matter

    SciTech Connect

    Reedy, R.C.

    1987-01-01

    The production rates of nuclides made by the galactic and solar cosmic rays are important in the interpretations of measurements made with lunar samples, meteorites, and cosmic spherules. Production rates of cosmogenic nuclides have been predicted by a variety of methods that are reviewed in this paper, ranging from systematic studies of one or a group of meteorites to purely theoretical calculations. Production rates can vary with the chemical composition and the preatmospheric depth of the sample and with the size and shape of the object. While the production systematics for cosmogenic nuclides are fairly well known, our ability to predict their production rates can be improved, with a corresponding increase in the scientific return. Additional detailed studies of cosmogenic nuclides in extraterrestrial objects are needed, especially for fairly small and very large objects. Nuclides made in simulation experiments and cross sections for many major nuclear reactions should be measured. Such studies are especially needed for the long-lived radionuclides that have only recently become readily measurable by accelerator mass spectrometry. 34 refs., 5 figs.

  19. Calculated cross sections for production and destruction of some long-lived nuclides of importance in fusion energy applications

    SciTech Connect

    Gardner, M.A.; Gardner, D.G.

    1993-07-08

    Knowledge of the production and destruction of long-lived species via neutrons, photons, and charged-particles is required in many fusion energy applications, such as reactor first-wall and blanket design, radioactive waste management, etc. Here we describe our calculational results for the production, via the (n,2n) reaction, of the following long-lived species: {sup 150}Eu(t{sub 1/2} = 36 y), {sup 152}Eu(t{sub 1/2} = 13 y), and {sup 192m2}Ir(t{sub 1/2} = 241 y). Some comments on calculations that we`ve made for destruction reactions of these species are also included.

  20. Calibrating a physical model based on Geant4 to calculate cosmogenic nuclide production rates on lunar surface

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Dong, Tiekuang; Ren, Zhongzhou

    2017-04-01

    A physical model based on the open-source toolkit Geant4 for production rates of cosmogenic nuclei on the lunar surface is proposed and calibrated. The fluxes of proton and neutron beneath the lunar surface are obtained by simulating the physical processes between the cosmic-ray particles and the lunar surface material. By combining the experimental proton cross sections and the a posteriori neutron cross sections, we calculate the production rate depth profiles of long-lived nuclei (10Be, 14C, 26Al, 36Cl, and 53Mn). Through comparing experimental and theoretical data for these nuclei, we find that for all the selected nuclei, experimental and theoretical production rate depth profiles agree well with each other by introducing a single normalization factor. It means that the physical model based on Geant4 can also reproduce the depth profiles of cosmogenic nuclei, and that this model can be used by everyone worldwide. In addition, we predict the production rates of three stable nuclei (21Ne, 22Ne, and 38Ar).

  1. Absolute isotopic composition of molybdenum and the solar abundances of the p-process nuclides Mo92,94

    NASA Astrophysics Data System (ADS)

    Wieser, M. E.; de Laeter, J. R.

    2007-05-01

    The isotopic composition of molybdenum has been measured with high precision using a thermal ionization mass spectrometer, the linearity of which has been verified by measuring the isotopically-certified reference material for strontium (NIST 987). The abundance sensitivity of the mass spectrometer in the vicinity of the molybdenum ion beams has been carefully examined to ensure the absence of tailing effects. Particular care was given to ensuring that potential isobaric interferences from zirconium and ruthenium did not affect the measurement of the isotopic composition of molybdenum. Gravimetric mixtures of two isotopically enriched isotopes, Mo92 and Mo98, were analyzed mass spectrometrically to calibrate the mass spectrometer, in order to establish the isotope fractionation of the spectrometer for the molybdenum isotopes. This enabled the “absolute” isotopic composition of molybdenum to be determined. An accurate determination of the isotopic composition is required in order to calculate the atomic weight of molybdenum, which is one of the least accurately known values of all the elements. The absolute isotope abundances (in atom %) of molybdenum measured in this experiment are as follows: Mo92=14.5246±0.0015; Mo94=9.1514±0.0074; Mo95=15.8375±0.0098; Mo96=16.672±0.019; Mo97=9.5991±0.0073; Mo98=24.391±0.018; and Mo100=9.824±0.050, with uncertainties at the 1s level. These values enable an atomic weight Ar(Mo) of 95.9602±0.0023 (1s) to be calculated, which is slightly higher than the current Standard Atomic Weight Ar(Mo) =95.94±0.02 and with a much improved uncertainty interval. These “absolute” isotope abundances also enable the Solar System abundances of molybdenum to be calculated for astrophysical purposes. Of particular interest are the Solar System abundances of the two p-process nuclides—Mo92 and Mo94, which are present in far greater abundance than p-process theory suggests. The Solar System abundances for Mo92 and Mo94 of 0.364±0

  2. The procedure and results of calculations of the equilibrium isotopic composition of a demonstration subcritical molten salt reactor

    NASA Astrophysics Data System (ADS)

    Nevinitsa, V. A.; Dudnikov, A. A.; Blandinskiy, V. Yu.; Balanin, A. L.; Alekseev, P. N.; Titarenko, Yu. E.; Batyaev, V. F.; Pavlov, K. V.; Titarenko, A. Yu.

    2015-12-01

    A subcritical molten salt reactor with an external neutron source is studied computationally as a facility for incineration and transmutation of minor actinides from spent nuclear fuel of reactors of VVER-1000 type and for producing 233U from 232Th. The reactor configuration is chosen, the requirements to be imposed on the external neutron source are formulated, and the equilibrium isotopic composition of heavy nuclides and the key parameters of the fuel cycle are calculated.

  3. The procedure and results of calculations of the equilibrium isotopic composition of a demonstration subcritical molten salt reactor

    SciTech Connect

    Nevinitsa, V. A. Dudnikov, A. A.; Blandinskiy, V. Yu.; Balanin, A. L.; Alekseev, P. N.; Titarenko, Yu. E.; Batyaev, V. F.; Pavlov, K. V.; Titarenko, A. Yu.

    2015-12-15

    A subcritical molten salt reactor with an external neutron source is studied computationally as a facility for incineration and transmutation of minor actinides from spent nuclear fuel of reactors of VVER-1000 type and for producing {sup 233}U from {sup 232}Th. The reactor configuration is chosen, the requirements to be imposed on the external neutron source are formulated, and the equilibrium isotopic composition of heavy nuclides and the key parameters of the fuel cycle are calculated.

  4. Nuclide Guide and International Chart of Nuclides - 2008

    NASA Astrophysics Data System (ADS)

    Golashvili, T.

    2009-08-01

    New versions of Nuclide Guide and Chart of the Nuclides were developed as a result of Russian-Chinese collaboration. The Nuclide Guide contains the basic information on more than 3000 radioactive and stable nuclides. The characteristics of isomers with half-lives more than 1 ms are included. For each nuclide spin, parity, mass of nuclide, magnetic moment (if available), mass excess, half-life or abundance, decay modes, branching ratios, emitted particles, energies of most intense gamma-rays and their intensities, decay energies and mean values of radiation energy per decay are given. For stable and natural long-lived nuclides cross-sections of thermal neutron induced activation are indicated. The information presented in the Guide was compiled from 5 sources: 1) ENSDF-2008, 2) atomic mass evaluation-2005 by Audi and Wapstra, 3) interactive data bases at web-sites , , 4) original evaluations of authors, 5) recent publications. The International Chart ot Nuclides was developed on the basis of information presented in Nuclide Guide.

  5. Chart of the Nuclides

    SciTech Connect

    Sartori, Enrico

    1999-03-23

    Nucleus is an interactive PC-based graphical viewer of NUBASE nuclear property data. NUBASE contains experimentally known nuclear properties, together with some values that have been estimated from extrapolation of experimental data for 3010 nuclides. NUBASE also contains data on those isomeric states that have half-lives greater than 1 millisecond; there are 669 such nuclides of which 58 have more than one isomeric state. The latest version of NUCLEUS-CHART has been corrected to include the names and the chemical symbols of the elements 104 to 109 that have been finally adopted by the Commission on Nomenclature of Inorganic Chemistry (CNIC) of the International Union of Pure and Applied Chemistry (IUPAC). They differ from those recommended by the same commission a few years before and that were widely used in the evaluations AME''95 and NUBASE''97. It results in some shuffling of the names and symbols, that may cause confusion in the near future. At AMDC we''ll be as careful as possible to try to avoid such confusion. In advance we apologize if any will occur in the future and recommend the user to always double check these few names.

  6. Cosmogenic nuclide budgeting of floodplain sediment transfer

    NASA Astrophysics Data System (ADS)

    Wittmann, H.; von Blanckenburg, F.

    2009-08-01

    Cosmogenic nuclides produced in quartz may either decay or accumulate while sediment is moved through a river basin. A change in nuclide concentration resulting from storage in a floodplain is potentially important in large drainage basins in which sediment is prone to repeated burial and remobilization as a river migrates through its floodplain. We have modeled depth- and time-dependent cosmogenic nuclide concentration changes for 10Be, 26Al, and 14C during sediment storage and mixing in various active floodplain settings ranging from confined, shallow rivers with small floodplains to foreland-basin scale floodplains traversed by deep rivers. Floodplain storage time, estimated from channel migration rates, ranges from 0.4 kyr for the Beni River basin (Bolivia) to 7 kyr for the Amazon River basin, while floodplain storage depth, estimated from channel depth, ranges from 1 to 25 m. For all modeled active floodplain settings, the long-lived nuclides 10Be and 26Al show neither significant increase in nuclide concentration from irradiation nor decrease from decay. We predict a hypothetical response time after which changes in 10Be or 26Al concentrations become analytically resolvable. This interval ranges from 0.07 to 2 Myr and exceeds in all cases the typical residence time of sediment in a floodplain. Due to the much shorter half life of 14C, nuclide concentrations modeled for the in situ-produced variety of this nuclide are, however, sensitive to floodplain storage on residence times of < 20 kyr. The cosmogenic nuclide composition of old deposits in currently inactive floodplains that have been isolated for periods of millions of years from the river that once deposited them is predicted to either increase or decrease in 10Be and 26Al concentration, depending on the depositional depth. These conditions can be evaluated using the 26Al/ 10Be ratio that readily discloses the depth and duration of storage. We illustrate these models with examples from the Amazon basin

  7. Nuclide production by primary cosmic-ray protons

    SciTech Connect

    Reedy, R.C.

    1986-01-01

    The production rates of cosmogenic nuclides in the solar system and in interstellar space were calculated for the primary protons in the galactic and solar cosmic rays. At 1 AU, the long-term average fluxes of solar protons usually produce many more atoms of a cosmogenic nuclide than the primary protons in the galactic cosmic rays (GCR), the exceptions being nuclides made only by high-energy reactions (like /sup 10/Be). Because the particle fluxes inside meteorites and other large objects in space include many secondary neutrons, the production rates are much higher and ratios inside large objects are often very different from those by just the primary GCR protons in small objects. The production rates of cosmogenic nuclides are calculated to vary by about factors of 2.5 during at typical 11-year solar cycle, in agreement with measurements of short-lived radionuclides in recently fallen meteorites. The production of cosmogenic nuclides by the GCR particles outside the heliosphere is higher than that by the modulated GCR primaries normally in the solar system. However, there is considerable uncertainty in the fluxes of interstellar protons and, therefore, in the production rates of cosmogenic nuclides in interstellar space. Production rates and ratios for cosmogenic nuclides would be able to identify particles that were small in space or that were exposed to an unmodulated spectrum of GCR particles. 25 refs., 2 figs., 2 tabs.

  8. Calculating Masses, Densities, And Compositions Of Alloys

    NASA Technical Reports Server (NTRS)

    De Groh, H.

    1990-01-01

    Metallurgical Programs include three simple programs calculating solutions to problems common to metallurgical engineers and persons making metal castings. First program calculates mass of binary ideal mixture (alloy). Second, calculates densities of binary ideal mixture. Third, converts atomic percentages of binary mixture to weight percentages. Uses simple equations to assist with routine calculations. Written in Microsoft QuickBASIC.

  9. Application of different nuclides in retrospective dosimetry

    SciTech Connect

    Konheiser, J.; Mittag, S.; Viehrig, H.W.; Gleisberg, B.

    2011-07-01

    The activities of nuclides produced via the neutron irradiation of reactor pressure vessel (RPV) steel are used to validate respective fluence calculations. Niobium, nickel, and technetium isotopes from RPV trepans of the decommissioned NPP Greifswald (VVER-440) have been analyzed. The activities were determined by TRAMO (Monte-Carlo) fluence calculations, newly applying 640 neutron-energy groups and ENDF/B7 data. Relative to earlier results, fluences up to 20% higher have been computed, leading to somewhat better agreement between measurement and calculation, particularly in the case of Tc-99. (authors)

  10. MATNORM: Calculating NORM using composition matrices

    NASA Astrophysics Data System (ADS)

    Pruseth, Kamal L.

    2009-09-01

    This paper discusses the implementation of an entirely new set of formulas to calculate the CIPW norm. MATNORM does not involve any sophisticated programming skill and has been developed using Microsoft Excel spreadsheet formulas. These formulas are easy to understand and a mere knowledge of the if-then-else construct in MS-Excel is sufficient to implement the whole calculation scheme outlined below. The sequence of calculation used here differs from that of the standard CIPW norm calculation, but the results are very similar. The use of MS-Excel macro programming and other high-level programming languages has been deliberately avoided for simplicity.

  11. Unconventional Nuclides for Radiopharmaceuticals

    PubMed Central

    Holland, Jason P.; Williamson, Matthew J.; Lewis, Jason S.

    2016-01-01

    Rapid and widespread growth in the use of nuclear medicine for both diagnosis and therapy of disease has been the driving force behind burgeoning research interests in the design of novel radiopharmaceuticals. Until recently, the majority of clinical and basic science research has focused on the development of 11C-, 13N-, 15O-, and 18F-radiopharmaceuticals for use with positron emission tomography (PET) and 99mTc-labeled agents for use with single-photon emission computed tomography (SPECT). With the increased availability of small, low-energy cyclotrons and improvements in both cyclotron targetry and purification chemistries, the use of “nonstandard” radionuclides is becoming more prevalent. This brief review describes the physical characteristics of 60 radionuclides, including β+, β−, γ-ray, and α-particle emitters, which have the potential for use in the design and synthesis of the next generation of diagnostic and/or radiotherapeutic drugs. As the decay processes of many of the radionuclides described herein involve emission of high-energy γ-rays, relevant shielding and radiation safety issues are also considered. In particular, the properties and safety considerations associated with the increasingly prevalent PET nuclides 64Cu, 68Ga, 86Y, 89Zr, and 124I are discussed. PMID:20128994

  12. Bloch-Sensitive Nuclides

    NASA Astrophysics Data System (ADS)

    Chubb, Talbot A.

    2005-03-01

    Documented condensed matter nuclear science includes Fleischmann and Pons radiationless dd fusion reactions, Iwamura alpha-addition transmutations, and Oriani MeV particle showers. All require partitioned coherent matter in which fractions of each single ``wave like" particle are entangledootnotetextT. A. Chubb, ``Bloch Nuclides, Iwamura Transmutations, and Oriani Showers", ICCF11 Abstract. If the work required to bring side-by-side deuterons into contact is somehow reduced enough, an energy-minimizing 2-body anti-correlation form of wave function replaces the "molecule" configuration, allowing cold fusion. In the Iwamura process, a second fusion step fuses 2 spin-zero ^4He^2^+Bloch ions to form ^8Be^4^+Bloch. The nuclear ground state energy of the product nucleus is a function of the number of fragments into which it is partitioned. It is ``Bloch sensitive", i.e., its energy level is a function of Nwell, the number of potential wells into which the ^8Be^4^+Bloch is partitioned. The dependence of energy on lattice parameter Nwell strongly couples nuclear and electromagnetic forces at the boundary of the coherently ordered volume, causing energy transfer to the lattice.

  13. Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter

    NASA Astrophysics Data System (ADS)

    Reedy, Robert C.

    2000-01-01

    There are two main types of cosmic rays that have sufficient energy to induce nuclear reactions -- the galactic cosmic rays (GCR) and solar cosmic rays (also called solar energetic particles). Both types of particles can have production rates and production ratios in the small objects often found in cold and hot deserts that are different from those seen for most meteorites, which typically have radii of approx.10-100 centimeters. GCR production rates are often lower than those for most meteorites. GCR production ratios, such as Ne-22/Ne-21, are also often different in small objects. Smaller meteoroids also are more likely to have nuclides made by solar-cosmic-ray (SCR) particles than typically-sized meteorites. The very small meteorite Salem had large amounts of SCR-produced radionuclides. Meteorites recovered in Antarctica are more likely to contain SCR-produced nuclides than other meteorites. Martian and lunar meteorites are also likely to have SCR-produced nuclides. Production rates and profiles for SCR-produced nuclides in meteoroids have been calculated previously. However, the cross sections for the nuclear reactions making many SCR-produced nuclides, such as Be-10, were not well measured then. New rates and profiles are calculated here using good cross sections for the reactions making these nuclides.

  14. Karlsruhe nuclide chart - new 9. edition 2015

    SciTech Connect

    Soti, Zsolt; Magill, Joseph; Pfennig, Gerda; Derher, Raymond

    2015-07-01

    Following the success of the 8. Edition of the Karlsruhe Nuclide Chart 2012, a new edition is planned for 2015. Since the 2012 edition, more than 100 nuclides have been discovered and about 1400 nuclides have been updated. In summary, the new 9. edition contains decay and radiation data on approximately 3230 ground state nuclides and 740 isomers from 118 chemical elements. The accompanying booklet provides a detailed explanation of the nuclide box structure used in the Chart. An expanded section contains many additional nuclide decay schemes to aid the user to interpret the highly condensed information in the nuclide boxes. The booklet contains - in addition to the latest values of the physical constants and physical properties - a periodic table of the elements, tables of new and updated nuclides, and a difference chart showing the main changes in the Chart graphically. (authors)

  15. The computation of body composition data using a programmable calculator.

    PubMed

    Withers, R T

    1986-01-01

    A body composition programme has been developed for the Texas Instruments TI 59 programmable calculator and printer. The methodology involves the determination of body density by underwater weighing with the ventilated residual volume being measured by helium dilution. Some of the labelled output variables included on the printout are: body density, percent body fat, fat mass and fat free mass.

  16. Plumbing neutron stars to new depths with the binding energy of the exotic nuclide 82Zn.

    PubMed

    Wolf, R N; Beck, D; Blaum, K; Böhm, Ch; Borgmann, Ch; Breitenfeldt, M; Chamel, N; Goriely, S; Herfurth, F; Kowalska, M; Kreim, S; Lunney, D; Manea, V; Minaya Ramirez, E; Naimi, S; Neidherr, D; Rosenbusch, M; Schweikhard, L; Stanja, J; Wienholtz, F; Zuber, K

    2013-01-25

    Modeling the composition of neutron-star crusts depends strongly on binding energies of neutron-rich nuclides near the N = 50 and N = 82 shell closures. Using a recent development of time-of-flight mass spectrometry for on-line purification of radioactive ion beams to access more exotic species, we have determined for the first time the mass of (82)Zn with the ISOLTRAP setup at the ISOLDE-CERN facility. With a robust neutron-star model based on nuclear energy-density-functional theory, we solve the general relativistic Tolman-Oppenheimer-Volkoff equations and calculate the neutron-star crust composition based on the new experimental mass. The composition profile is not only altered but now constrained by experimental data deeper into the crust than before.

  17. Lattice calculation of composite dark matter form factors

    NASA Astrophysics Data System (ADS)

    Appelquist, T.; Brower, R. C.; Buchoff, M. I.; Cheng, M.; Cohen, S. D.; Fleming, G. T.; Kiskis, J.; Lin, M. F.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Schaich, D.; Schroeder, C.; Syritsyn, S.; Voronov, G.; Vranas, P.; Wasem, J.

    2013-07-01

    Composite dark matter candidates, which can arise from new strongly-coupled sectors, are well-motivated and phenomenologically interesting, particularly in the context of asymmetric generation of the relic density. In this work, we employ lattice calculations to study the electromagnetic form factors of electroweak-neutral dark-matter baryons for a three-color, QCD-like theory with Nf=2 and 6 degenerate fermions in the fundamental representation. We calculate the (connected) charge radius and anomalous magnetic moment, both of which can play a significant role for direct detection of composite dark matter. We find minimal Nf dependence in these quantities. We generate mass-dependent cross sections for dark matter-nucleon interactions and use them in conjunction with experimental results from XENON100, excluding dark matter candidates of this type with masses below 10 TeV.

  18. Production Rates of Cosmogenic Nuclides in the Knyahinya L-Chondrite

    NASA Technical Reports Server (NTRS)

    Kim, K. J.; Reedy, R. C.

    2004-01-01

    The production rates of spallogenic radionuclides and stable isotopes in the L-chondrite Knyahinya were investigated using the MCNPX code. Numerous cosmogenic nuclides had been measured in many Knyahinya samples. The pre-atmospheric size and sample locations of Knyahinya are well known, thus Knyahinya is a good test case for cosmogenic-nuclide production-rate calculations. Our calculated profiles were compared to the measurements to determine effective proton fluxes.

  19. 2016 Update of the discoveries of nuclides

    NASA Astrophysics Data System (ADS)

    Thoennessen, M.

    The 2016 update of the discovery of nuclide project is presented. Only 12 new nuclides were observed for the first time in 2016. A large number of isotopes are still only published in conference proceedings or internal reports. No changes to earlier assignments were made.

  20. New nuclide sup 263 Ha

    SciTech Connect

    Kratz, J.V.; Gober, M.K.; Zimmermann, H.P. ); Schaedel, M.; Bruechle, W.; Schimpf, E. ); Gregorich, K.E.; Tuerler, A.; Hannink, N.J.; Czerwinski, K.R.; Kadkhodayan, B.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. ); Gaeggeler, H.; Jost, D.; Kovacs, J.; Scherer, U.W.; Weber, A. )

    1992-03-01

    A new nuclide {sup 263}Ha was produced in the bombardment of a {sup 249}Bk target with 93-MeV {sup 18}O ions. It was detected via spontaneous fission counting and was shown to have a half-life of about 0.5 min. This activity was also separated from the reaction products by automated rapid chemical separations using cation-exchange chromatography in 0.05{ital M} {alpha}-hydroxyisobutyric acid. After chemical separation, {sup 263}Ha was found to decay by spontaneous fission (57{sub {minus}15}{sup +13}%) and by {alpha} emission ({ital E}{sub {alpha}}=8.35 MeV, 43%) with a half-life of 27{sub {minus}7}{sup +10} s. The spontaneous fission fragment energy spectrum is compatible with an average total kinetic energy of about 200 MeV.

  1. Clouds Composition in Super-Earth Atmospheres: Chemical Equilibrium Calculations

    NASA Astrophysics Data System (ADS)

    Kempton, Eliza M.-R.; Mbarek, Rostom

    2015-12-01

    Attempts to determine the composition of super-Earth atmospheres have so far been plagued by the presence of clouds. Yet the theoretical framework to understand these clouds is still in its infancy. For the super-Earth archetype GJ 1214b, KCl, Na2S, and ZnS have been proposed as condensates that would form under the condition of chemical equilibrium, if the planet’s atmosphere has a bulk composition near solar. Condensation chemistry calculations have not been presented for a wider range of atmospheric bulk composition that is to be expected for super-Earth exoplanets. Here we provide a theoretical context for the formation of super-Earth clouds in atmospheres of varied composition by determining which condensates are likely to form, under the assumption of chemical equilibrium. We model super-Earth atmospheres assuming they are formed by degassing of volatiles from a solid planetary core of chondritic material. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350-3,000 K. Clouds should form along the temperature-pressure boundaries where the condensed species appear in our calculations. The super-Earth atmospheres that we study range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solar and super-solar, thereby spanning a diverse range of atmospheric composition that is appropriate for low-mass exoplanets. Some condensates appear across all of our models. However, the majority of condensed species appear only over specific ranges of H:O and C:O ratios. We find that for GJ 1214b, KCl is the primary cloud-forming condensate at solar composition, in agreement with previous work. However, for oxidizing atmospheres, where H:O is less than unity, K2SO4 clouds form instead. For carbon-rich atmospheres with super-solar C:O ratios, graphite clouds additionally appear. At

  2. Cosmic-ray interactions and dating of meteorite stranding surfaces with cosmogenic nuclides

    SciTech Connect

    Reedy, R.C.

    1988-01-01

    A wide variety of products from cosmic-ray interactions have been measured in terrestrial or extraterrestrial samples. These ''cosmogenic'' products include radiation damage tracks and rare nuclides that are made by nuclear reactions. They often have been used to determine the fluxes and composition of cosmic-ray particles in the past, but they are usually used to study the history of the ''target'' (such as the time period that it was exposed to cosmic-ray particles). Products made by both the high-energy galactic cosmic rays and energetic particles emitted irregularly from the Sun have been extensively studied. Some of these cosmogenic products, especially nuclides, have been or can be applied to studies of Antarctic meteorite stranding surfaces, the ice surfaces in Antarctica where meteorites have been found. Cosmogenic nuclides studied in samples from Antarctica and reported by others elsewhere in this volume include those in meteorites, especially radionuclides used to determine terrestrial ages, and those made in situ in terrestrial rocks. Cosmogenic nuclides made in the Earth's atmosphere or brought in with cosmic dust have also been studied in polar ice, and it should also be possible to measure nuclides made in situ in ice. As an introduction to cosmogenic nuclides and their applications, cosmic rays and their interactions will be presented below and production systematics of cosmogenic nuclides in these various media will be discussed later. 20 refs., 2 tabs.

  3. Simulations of Terrestrial in-situ Cosmogenic-Nuclide Production

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.; Nishiizumi, K.; Lal, D.; Arnold, J. R.; Englert, P. A. J.; Klein, J.; Middleton, R.; Jull, A. J. T.; Donahue, D. J.

    1994-01-01

    Targets of silicon and silicon dioxide were irradiated with spallation neutrons to simulate the production of long-lived radionuclides in the surface of the Earth. Gamma-ray spectroscopy was used to measure Be-7 and Na-22, and accelerator mass spectrometry was used to measure Be-10, C-14, and Al-26. The measured ratios of these nuclides are compared with calculated ratios and with ratios from other simulations and agree well with ratios inferred from terrestrial samples.

  4. Addressing nuclides not in the CAP88-PC Version-3 library.

    PubMed

    McNaughton, Michael; Brock, Burgandy; Eisele, William; Fuehne, David; Green, Andrew; Whicker, Jeffrey

    2013-08-01

    Versions of the computer program, CAP88, are widely used to calculate the radiological doses from radionuclides emitted into the air. CAP88-PC Version-3 includes an extensive library of radionuclides, but there are many more that are not included. Surrogates are often used to substitute for nuclides not in the library, though the results are usually overestimates. This paper addresses nuclides that are not in the library and describes methods to obtain more accurate results.

  5. Thick-Target Simulation Experiments as a Basis for Consistent Modeling of Cosmogenic Nuclide Production in Extraterrestrial Matter

    NASA Astrophysics Data System (ADS)

    Michel, R.; Lange, H.-J.; Leya, I.; Herpers, U.; Meltzow, B.; Dittrich-Hannen, B.; Suter, M.; Kubik, P. W.

    1995-09-01

    Cosmogenic nuclide production rates in meteoroids depend on size and bulk chemical composition of the meteoroid, on the shielding depth and the chemical composition of a sample in it, on spectral distribution, composition and intensity of solar and galactic cosmic radiation, and on the possibly complex exposure history. Except for bulk and sample chemical compositions, all parameters are unknown and must be reconstructed. In order to interpret cosmogenic nuclide abundances in meteorites with respect to their exposure histories, to reconstruct the preatmospheric shapes of the meteoroids and to draw conclusions about long-term spectral distributions and intensities of the cosmic radiation, reliable model calculations of producton rates must be available. The lack of knowledge about the parameters which influence the production rates causes ambiguity of empirical and physical model calculations, if exclusively meteorite data are taken into account. Physical models of cosmogenic nuclide production in meteoroids without free parameters can be established on the basis of thick-target experiments by which the cosmic ray exposure of meteoroids in space is simulated as close as possible under completely controlled conditions. During recent years, we have performed five such experiments to simulate the exposure of meteoroids to galactic protons [1-6]. Here, we report new results on the latest one of these experiments, in which an artificial iron meteoroid made of steel with a radius of 10 cm was isotropically irradiated by 1.6 GeV protons [4,5]. Measurements and evaluation are now completed for shortand mediumlived radionuclides. Results for long-lived nuclides by AMS and of stable rare gas isotopes are partially available with additional measurements still going on. The results obtained up to now for radionuclide production are presented and discussed with respect to some aspects of the production of cosmogenic nuclides in iron meteoroids and of the influence of bulk

  6. Cosmogenic Nuclides Study of Large Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Hutzler, A.; Smith, T.; Rochette, P.; Bourles, D. L.; Leya, I.; Gattacceca, J.

    2014-09-01

    Six large iron meteorites were selected (Saint-Aubin, Mont-Dieu, Caille, Morasko, Agoudal, and Gebel Kamil). We measured stable and radiogenic cosmogenic nuclides, to study pre-atmospheric size, cosmic-ray exposure ages and terrestrial ages.

  7. Calculation of colour resulting from composite/compomer layering techniques.

    PubMed

    Lee, Y-K; Powers, J M

    2004-11-01

    This study determined the influence of optical properties of constituent layers on the colour of double-layer aesthetic filling materials. Multiple regression equations for the Commission Internationale de I'Eclairage (CIE) L*, a* and b* of layered materials were calculated from the optical values of the covering and underlying layers. Specimens (10 mm diameter, 1 mm thickness) of two light-cured resin composites and one compomer of seven to 11 shades were used. CIE L*, a* and b* values of each specimen were measured with a colour spectrophotometer backed by a standard white background. The scattering coefficient (S), absorption coefficient (K), contrast ratio (C) and translucency parameter (T) were calculated. Double-layered specimens were formed in optical contact by joining two different shades from the same material, or resin composite as covering with a compomer underlying layer. Each of the L*, a* and b* of layered material was used as a dependent variable, and 14 optical values of underlying and covering layers were used as independent variables in forward regression analysis (P = 0.01). CIE L* after layering had a positive correlation with S of covering layer (correlation coefficient; beta = 0.79-0.91, P < 0.01) and a correlation with L* of underlying layer (beta = 0.14-0.16). CIE a* after layering had a correlation with a* of covering layer (beta = 0.83-0.94) and a correlation with a* of underlying layer (beta = 0.30-0.56). CIE b* after layering had a correlation with b* of covering layer (beta = 0.77-0.90) and a correlation with T of covering layer (beta = 0.40-0.59). The layered colour of these materials can be predicted by the derived regression equations within the limitations of this study. CIE L*, a* and b* values of double-layer material are mainly influenced by S, CIE a* and b* of covering layer, respectively.

  8. Simplified method for calculation of equilibrium plasma composition

    NASA Astrophysics Data System (ADS)

    Rydalevskaya, Maria A.

    2017-06-01

    In this work, a simplified method for the evaluation of equilibrium composition of plasmas consisted of monoatomic species is proposed. Multicomponent gas systems resulting from thermal ionization of spatially uniform mixtures are assumed enough rarefied to be treated as ideal gases even after multiple ionization steps. The method developed for the calculation of equilibrium composition of these mixtures makes use of the fundamental principles of statistical physics. Equilibrium concentrations of mixture components are determined by integration of distribution functions over the space of momentum and summation over electronic energy levels. These functions correspond to the entropy maximum. To determine unknown parameters, the systems of equations corresponding to the normalization conditions are derived. It is shown that the systems may be reduced to one algebraic equation if the equilibrium temperature is known. Numeral method to solve this equation is proposed. Special attention is given to the ionized mixtures, generated from the atoms of a single chemical species and the situations, when in the gas only the first- or the first- and second-order ionization are possible.

  9. Nuclear fission of neutron-deficient protactinium nuclides

    SciTech Connect

    Nishinaka, I.; Nagame, Y.; Tsukada, K.; Ikezoe, H.; Sueki, K.; Nakahara, H.; Tanikawa, M.; Ohtsuki, T.

    1997-08-01

    Fragment velocity, kinetic energy, mass yield, and element yield distributions in the fission of neutron-deficient Pa isotopes produced in the reactions of {sup 16}O and {sup 18}O on {sup 209}Bi have been measured at incident beam energies near and above the Coulomb barriers by the time-of-flight and radiochemical methods. An asymmetric mass-division component has been observed. Measured fission cross sections were compared with the results of statistical model calculations which take into account two fission barrier heights for symmetric and asymmetric yields. The fission barrier height deduced for the asymmetric fission is found slightly lower than that for the symmetric one. The difference between the two barrier heights in the fission of the present protactinium nuclides (N{approximately}135) is considerably smaller than that in the neutron-rich nuclide of {sup 233}Pa (N{approximately}142), indicating that the difference sensitively depends on the neutron number of the fissioning nuclide. {copyright} {ital 1997} {ital The American Physical Society}

  10. Surficial Studies of Mars Using Cosmogenic Nuclides

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.

    2001-01-01

    Cosmogenic nuclides (CNs) are produced by cosmic-ray nuclear interactions with target nuclei in rocks, soils, ice, and the atmosphere. Cosmogenic nuclides have been widely used for investigation of solar system matter for several decades. Stable nuclides, such as He-3, Ne-21, and Ar-38, are built up over time as the surface is exposed to cosmic rays. The concentrations of cosmogenic radionuclides, such as Be-10, Al-26, and C-14 also build up with exposure time but reach saturation values after several half-lives. Especially since the development of accelerator mass spectrometry (AMS), CNs in terrestrial samples have been routinely used for geomorphic studies such as glaciation, surface erosion, and tectonics, and studies of atmospheric and ocean circulation. Cosmogenic nuclides on Mars will be able to answer questions of exposure ages, erosion rates, tectonic events, and deposition rates of sediments and/or volatiles. The concentrations of cosmogenic stable nuclides give the integrated exposure time of the rock/mineral, and the activities of radionuclides give recent records for times back as long as a few half-lives.

  11. Surficial Studies of Mars Using Cosmogenic Nuclides

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.

    2001-01-01

    Cosmogenic nuclides (CNs) are produced by cosmic-ray nuclear interactions with target nuclei in rocks, soils, ice, and the atmosphere. Cosmogenic nuclides have been widely used for investigation of solar system matter for several decades. Stable nuclides, such as He-3, Ne-21, and Ar-38, are built up over time as the surface is exposed to cosmic rays. The concentrations of cosmogenic radionuclides, such as Be-10, Al-26, and C-14 also build up with exposure time but reach saturation values after several half-lives. Especially since the development of accelerator mass spectrometry (AMS), CNs in terrestrial samples have been routinely used for geomorphic studies such as glaciation, surface erosion, and tectonics, and studies of atmospheric and ocean circulation. Cosmogenic nuclides on Mars will be able to answer questions of exposure ages, erosion rates, tectonic events, and deposition rates of sediments and/or volatiles. The concentrations of cosmogenic stable nuclides give the integrated exposure time of the rock/mineral, and the activities of radionuclides give recent records for times back as long as a few half-lives.

  12. Production systematics of cosmogenic nuclides in the earth

    SciTech Connect

    Reedy, R.C.

    1995-01-01

    The high-energy particles in the galactic cosmic rays, (GCR) can produce nuclides deep in any object exposed to them. These cosmic-ray-produced (cosmogenic) nuclides have been extensively studied during the last four decades, mainly in meteorites and lunar samples (e.g., 1,2). In extraterrestrial matter, several approaches have been used to determine the production systematics of these cosmogenic nuclides. Production rates of most cosmogenic nuclides in the Earth axe much lower, especially those nuclides made ``in situ`` in the Earth`s surface. Many of these @trial cosmogenic nuclides are only now being measured because of improved techniques, such as accelerator mass spectrometry (AMS). There have been very few determinations of the production rates of nuclides made in the Earth by cosmic rays. The work being done for terrestrial cosmogenic nuclides is following the approaches used for, studying the production of extraterrestrial nuclides.

  13. Cosmogenic nuclides in the Brenham pallasite

    NASA Astrophysics Data System (ADS)

    Honda, M.; Caffee, M. W.; Miura, Y. N.; Nagai, H.; Nagao, K.; Nishiizumi, K.

    2002-12-01

    Cosmic-ray-produced (cosmogenic) nuclides were studied in fragments of the Brenham pallasite, a large stony iron meteorite. The contents of light noble gases (He, Ne, and Ar) and long-lived radionuclides (10Be, 26Al, 36Cl, and 53Mn), produced by nuclear reactions with cosmic rays, were measured in the separated metal and olivine phases from numerous samples representing a wide range of shielding conditions in the meteoroid. The distribution of cosmogenic nuclide concentrations in the metal follows patterns similar to that observed in large iron meteorites. Shielding effects were estimated from the relative proportions of low- and high-energy reaction products. The production rates varied, from surface to interior, by a factor of more than several hundred. The 36Cl-36Ar cosmic-ray exposure age of Brenham is 156 +/- 8 Myr. This determination is based on a multiple nuclide approach that utilizes cosmogenic nuclide pairs. This approach not only yields a "shielding independent" exposure age but also demonstrates that the production of cosmogenic nuclides occurred in a single stage. The depth profiles of 10Be in the stone phase and 53Mn in the metal phase are shown superimposed on corresponding profiles from the Apollo 15 long drill core. Surprisingly low abundances of lithophile elements, such as K, U, and Th, provided a unique opportunity to examine the production systematics of those nuclides whose inventories typically have significant contributions from non-cosmogenic sources, particularly radiogenic contributions. The U and Th contents of the olivine samples are extremely low, allowing detection of cosmogenic 4He production from oxygen, magnesium, silicon, and iron.

  14. Simulations of terrestrial in-situ cosmogenic-nuclide production

    SciTech Connect

    Reedy, R.C.; Nishiizumi, K.; Arnold, J.R.; Lal, D.; Englert, P.A.J.; Klein, J.; Middleton, R.; Jull, A.J.T.; Donahue, D.J.

    1993-12-31

    Targets of silicon and silicon dioxide were irradiated with spallation neutrons to simulate the production of long-lived radionuclides in the surface of the earth. Gamma-ray spectroscopy was used to measure {sup 7}Be and {sup 22}Na, and accelerator mass spectrometry was used to measure {sup 10}Be, {sup 14}C, and {sup 26}Al. The measured ratios of these nuclides are compared with calculated ratios and with ratios from other simulations and agree well with ratios inferred from terrestrial samples.

  15. Time-of-Flight Mass Measurements of Neutron Rich Nuclides

    NASA Astrophysics Data System (ADS)

    Estrade, A.; Matos, M.; Amthor, A. M.; Becerril, A.; Elliot, T.; Lorusso, G.; Rogers, A.; Schatz, H.; Bazin, D.; Gade, A.; Portillo, M.; Stolz, A.; Galaviz, D.; Pereira, J.; Shapira, D.; Smith, E.; Wallace, M.

    2008-10-01

    Nuclear masses of neutron rich isotopes in the region of Z ˜ 20-30 have been measured using the time-of-flight technique at the National Superconducting Cyclotron Laboratory (NSCL). The masses of 5 isotopes have been measured for the first time, and the precision of several other masses has been improved. The time-of-flight technique has shown the potential to access nuclear masses very far from stability when applied at radioactive beam facilities like the NSCL. Such measurements are important for understanding nuclear structure far from the valley of β-stability, and provide valuable information for astrophysical model calculations of processes involving very unstable nuclides.

  16. New mass measurements of neutron rich nuclides at the NSCL.

    NASA Astrophysics Data System (ADS)

    Estrade, Alfredo; Matos, Milan; Amthor, Matthew; Bazin, Daniel; Becerril, Ana; Elliot, Thom; Gade, Alexandra; Galaviz, Daniel; Lorusso, Giuseppe; Pereira, Jorge; Portillo, Mauricio; Rogers, Andrew; Schatz, Hendrik; Shapira, Dan; Smith, Ed; Stolz, Andreas; Wallace, Mark

    2007-10-01

    A mass measurement of exotic isotopes in the region of 68Fe has been performed at the NSCL using the time-of-flight technique recently established. Experimental knowledge of the mass of very neutron rich nuclides is an important input for astrophysical applications, such as nucleosynthesis during the r-process and the evolution of matter in the crust of an accreting neutron star, where present calculations are mostly limited to using theoretical mass extrapolations. We present the details of the experimental set up, as well as preliminary results.

  17. A model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    Reedy, R. C.

    1985-02-01

    A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions and energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g/cm (2). Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurments of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth.

  18. Model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides

    SciTech Connect

    Reedy, R.C.

    1984-01-01

    A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions of energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g cm/sup -2/. Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurements of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth. 25 references, 8 figures.

  19. Accelerator experiments on the contribution of secondary particles to the production of cosmogenic nuclides in meteorites

    NASA Technical Reports Server (NTRS)

    Dragovitsch, P.; Englert, P.

    1985-01-01

    Through the interaction of galactic cosmic particle radiation (GCR) a wide variety of cosmogenic nuclides is produced in meteorites. They provide historical information about the cosmic radiation and the bombarded meteorites. An important way to understand the production mechanisms of cosmogenic nuclides in meteorites is to gather information about the depth and size dependence of the build-up of Galactic Rays Cosmic-secondary particles within meteorites of different sizes and chemical compositions. Simulation experiments with meteorite models offer an alternative to direct observation providing a data basis to describe the development and action of the secondary cascade induced by the GCR in meteorites.

  20. Production profiles of nuclides by galactic-cosmic-ray particles in small meteoroids

    NASA Astrophysics Data System (ADS)

    Reedy, R. C.; Masarik, J.

    Many of the meteorites found in cold and hot deserts are small, and many were small bodies in space. Production of cosmic-ray-produced (cosmogenic) nuclides in small meteoroids is expected to be different than that in the larger meteoroids typically studied, with lower levels of nuclide production by galactic-cosmic-ray (GCR) particles and possibly significant production by solar-cosmic-ray (SCR) protons. Motivated by the cosmogenic-nuclide measurements for the very small Salem meteorite and for cosmic spherules, which show high levels of SCR production, we have reported earlier nuclide production rates by SCR protons in small objects in space. The GCR production rates reported for small meteoroids have not been tested and were expected to be poor for meteoroids with radii less than 40 g/cm2 because of the very simple nature of that semi-empirical model (only one free parameter) and because the mix of neutrons and protons is different (relatively more protons) than that in the model, which was based on larger objects. Thus we have calculated produciton rates for nuclides mad by GCR particles in small objects with a physical model that is much better suited for unusual targets.

  1. A three dimensional calculation of elastic equilibrium for composite materials

    NASA Technical Reports Server (NTRS)

    Lustman, Liviu R.; Rose, Milton E.

    1986-01-01

    A compact scheme is applied to three-dimensional elasticity problems for composite materials, involving simple geometries. The mathematical aspects of this approach are discussed, in particular the iteration method. A vector processor code implementing the compact scheme is presented, and several numerical experiments are summarized.

  2. Measurements of nuclide yields in neutron-induced fission of natural uranium for SPIRAL2

    NASA Astrophysics Data System (ADS)

    Lhersonneau, G.; Malkiewicz, T.; Trzaska, W. H.

    2014-01-01

    Cross-sections for nuclide production in fast-neutron induced fission of natural uranium are part of the input for predictions of yields of neutron-rich nuclides obtainable at Radioactive Ion Beam facilities. We first describe the neutron spectra produced according to the scheme once envisaged for SPES (protons on an enriched 13C target) and the one adopted for SPIRAL2 (deuterons on natural carbon), which both have been measured at JYFL. We then present the measurements of Z-splits in isobaric chains performed at IGISOL. When coupled with the fission cross-section and A-splits for the relevant neutron spectrum, they allow estimates of nuclide cross-sections. It looks that calculations, even those based on modern libraries, are too optimistic by about a factor of two.

  3. Cosmogenic nuclides in cometary materials: Implications for rate of mass loss and exposure history

    NASA Technical Reports Server (NTRS)

    Herzog, G. F.; Englert, P. A. J.; Reedy, R. C.

    1989-01-01

    As planned, the Rosetta mission will return to earth with a 10-kg core and a 1-kg surface sample from a comet. The selection of a comet with low current activity will maximize the chance of obtaining material altered as little as possible. Current temperature and level of activity, however, may not reliably indicate previous values. Fortunately, from measurements of the cosmogenic nuclide contents of cometary material, one may estimate a rate of mass loss in the past and perhaps learn something about the exposure history of the comet. Perhaps the simplest way to estimate the rate of mass loss is to compare the total inventories of several long-lived cosmogenic radionuclides with the values expected on the basis of model calculations. Although model calculations have become steadily more reliable, application to bodies with the composition of comets will require some extension beyond the normal range of use. In particular, the influence of light elements on the secondary particle cascade will need study, in part through laboratory irradiations of volatile-rich materials. In the analysis of cometary data, it would be valuable to test calculations against measurements of short-lived isotopes.

  4. Calculation of Gamma Photon Propagation Processes in a Composite Material

    NASA Astrophysics Data System (ADS)

    Pavlenko, V. I.; Cherkashina, N. I.; Noskov, A. V.; Yastrebinskii, R. N.; Sokolenko, I. V.

    2016-12-01

    The paper presents the data on radiation protection properties of a composite material consisting of the glass-crystalline matrix and nanotubular chrysotile modified by inserting PbWO4 into its structure, as well as the data on key physico-mechanical characteristics of the composite, such as density, ultimate compression strength, microhardness, porosity, water absorption, temperature stability, and thermostability. It was established that in addition to radiation protection properties, the examined material has enhanced practical design characteristics and can be used as a construction material. The propagation of gamma photons with different energy levels through the composite material is examined. A graph is built for dependence of the linear gamma radiation attenuation coefficient (μ) on energy in the range 0.25 < E < 1.4 MeV. The contribution of the Compton effect and the photoeffect into the total linear gamma photon flow attenuation coefficient are considered. It is established that at energy levels from 0.25 to 0.7 MeV, photoeffect makes the largest contribution to the total linear gamma radiation attenuation coefficient, while at energy levels from 0.7 to 1.4 MeV the largest contribution is made by the Compton effect. Error of the linear gamma radiation attenuation coefficient based on estimates and experimental data is very small and equals around 2%, which confirms that the developed model is correct. It is established that the composite possesses enhanced radiation protection characteristics, far exceeding those of iron and slightly (by 10.4%) yielding to pure lead.

  5. Neutron multiplicities for the transplutonium nuclides

    SciTech Connect

    Holden, N.E.; Zucker, M.S.

    1985-01-01

    This paper continues, with respect to the transplutonium nuclides, earlier efforts to collate and evaluate data from the scientific literature on the prompt neutron multiplicity distribution from fission and its first moment = ..sigma..nuPnu. The isotopes considered here for which P/sub nu/ and or data (or both) were found in the literature are of americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), and nobelium (No).

  6. Significance of the effect of mineral alteration of nuclide migration

    SciTech Connect

    Murakami, Takashi; Ohnuki, Toshihiko; Isobe, Hiroshi; Sato, Tsutomu; Yanase, Nobuyuki; Kimura, Hideo

    1994-12-31

    In order to clarify the effect of mineral alteration on nuclide migration, we examined the processes, mechanisms, and kinetics of chlorite weathering, and the uranium concentrations in minerals and rocks at Koongarra, Australia. The observed concentrations of uranium in rocks were compared to those calculated. The sequence of chlorite weathering may be simply expressed as a chlorite {yields} vermiculite {yields} kaolinite conversion. These minerals occur as a function of depth, which corresponds well to uranium concentrations on the meter scale. Iron minerals, closely related to the uranium redistribution, are released during the weathering. The first-order kinetic model of the weathering process suggests that the weathering rate is not constant but time-dependent. The uranium concentrations are qualitatively proportional to the extent of the weathering, the weathered part having higher uranium concentration. Uranium mainly occurs with iron minerals, and sub micron sized saleeite, a uranyl phosphate, is one of the most probable uranyl phases associated with the iron minerals. The uranium fixation mechanisms are probably saleeite microcrystal coprecipitation and sorption to the iron minerals. Our model, which describes uranium concentrations in rocks as a function of time, shows that the transition zone (a vermiculite dominant area) plays an important role in the uranium migration. We have established that weathering of chlorite has affected the redistribution of uranium for more than one million years. The present study demonstrates the significance of mineral alteration when we estimate nuclide migration for geologic time.

  7. Cosmogenic nuclide dating of glaciofluvial deposits: insights from the Alps

    NASA Astrophysics Data System (ADS)

    Akcar, Naki; Ivy-Ochs, Susan; Alfimov, Vasily; Claude, Anne; Reber, Regina; Christl, Marcus; Vockenhuber, Christof; Schlunegger, Fritz; Rahn, Meinert; Dehnert, Andreas; Schlüchter, Christian

    2015-04-01

    Cosmogenic 10Be and 26Al can be employed to reconstruct the chronology of sediment layers. Accumulation of these can be used to exposure date the sediment layer as the variation of cosmogenic nuclide concentration with depth can be modeled. Decay of 10Be and 26Al in the samples from a well-defined single bed in a deposit enables the modeling of the post-burial component and the determination of the 26Al/10Be at the time of burial. The isochron-burial age can then be calculated from the initial and the measured ratios. In this study, we focus on the depth-profile and isochron-burial dating of the oldest Quaternary deposits of the Alpine Foreland. These are called Swiss Deckenschotter (cover gravels) as they build mesa-type hill tops on the Mesozoic or Cenozoic bedrock of the Swiss Alpine forelands. Deckenschotter consists of glaciofluvial gravel layers intercalated with glacial and/or overbank deposits. Although previously morphostratigraphically correlated with Günz and Mindel glaciations of Penck and Brückner, the Swiss Deckenschotter is likely much older, and their chronostratigraphy is not well constrained. In order to reconstruct the chronology of these deposits, we studied two Deckenschotter outcrops in abandoned gravel pits in Mandach (507 m a.s.l.) and Siglistorf (530 m a.s.l.) in canton Zurich. We collected four samples from Mandach for 10Be analysis and more than 30 clasts of different lithology, shape and size from a single stratigraphic horizon in Siglistorf among which we processed 19 clasts for 10Be and 26Al analysis. 10Be concentrations of the Mandach samples vary between 10000 and 30000 at/g. Based on these, we calculated a modal depth-profile age of around 1.0 Ma. Among Siglistorf samples, four did not yield successful 26Al measurements and two were unsuccessful for 10Be. Most of the samples have low nuclide concentrations, i.e. <20000 10Be at/g and <150000 26Al at/g. The 26Al/10Be ratio of eight samples was above the surface ratio of 6

  8. Comparison of flash calculations in compositional reservoir simulation

    SciTech Connect

    Wang, P.; Barker, J.W.

    1995-12-31

    This paper compares several recent flash algorithms in the context of compositional reservoir simulation. We evaluate three reduced equation methods: (1) the 3-equation flash of Michelsen, which applies only when all binary interaction coefficients (k{sub ij}) are zero; (2) Hendricks and van Bergen; and (3) Kaul and Thrasher. We also evaluate; (4) the non-iterative flash; and (5) the method of Young. We find that these last two methods, which are similar in concept, work well for reservoir simulation where the flash must be closely coupled with the solution of the pressure equation, and where a good initial guess is generally available. The reduced equation flashes offer no significant improvement over these other methods; this is true even for the 3-equation flash which solves a simpler problem (with k{sub ij} = 0).

  9. Prostate Mechanical Imaging: 3-D Image Composition and Feature Calculations

    PubMed Central

    Egorov, Vladimir; Ayrapetyan, Suren; Sarvazyan, Armen P.

    2008-01-01

    We have developed a method and a device entitled prostate mechanical imager (PMI) for the real-time imaging of prostate using a transrectal probe equipped with a pressure sensor array and position tracking sensor. PMI operation is based on measurement of the stress pattern on the rectal wall when the probe is pressed against the prostate. Temporal and spatial changes in the stress pattern provide information on the elastic structure of the gland and allow two-dimensional (2-D) and three-dimensional (3-D) reconstruction of prostate anatomy and assessment of prostate mechanical properties. The data acquired allow the calculation of prostate features such as size, shape, nodularity, consistency/hardness, and mobility. The PMI prototype has been validated in laboratory experiments on prostate phantoms and in a clinical study. The results obtained on model systems and in vivo images from patients prove that PMI has potential to become a diagnostic tool that could largely supplant DRE through its higher sensitivity, quantitative record storage, ease-of-use and inherent low cost. PMID:17024836

  10. Paleo-erosion rates versus paleo-erosion processes from cosmogenic nuclide concentrations in sedimentary archives

    NASA Astrophysics Data System (ADS)

    Schildgen, Taylor; Garcin, Yannick; Savi, Sara; Tofelde, Stefanie; Wittmann, Hella; Strecker, Manfred

    2017-04-01

    Paleo-erosion rates derived from cosmogenic nuclide concentrations in sedimentary archives are commonly observed to differ from modern rates, in some cases by several orders of magnitude. However, the meaning of these rates can be unclear when we consider the averaging timescale (and presumed lag) of the cosmogenic nuclide technique in recording erosion rates, grain-size dependencies in nuclide concentrations, and assumptions inherent to the detrital approach. These issues can complicate our ability to interpret landscape response to past climate change from cosmogenic nuclides. In general, the cosmogenic nuclide concentration in sediment is inversely related to the catchment mean erosion rate. However, several studies, including ours from the Central Andes, have suggested that low nuclide concentrations from fill terrace sediment coupled with a strong grain-size dependence in nuclide concentrations point to a greater importance of landslide activity in the past. In such settings, cosmogenic nuclide concentrations may provide clear signals of changes in erosion processes, but are difficult to interpret in terms of changes in erosion rates. These complications may be reduced in low-relief catchments, where landsliding is unlikely. Such is the case for the semi-arid Baragoi catchment of East Africa, which was affected by a wetter climate during the African Humid Period (ca. 15-6 cal. kyr BP). From that time period, we calculate paleo-erosion rates from cosmogenic nuclides within deltaic sediments that are up to 7x faster than modern rates. Moreover, erosion rates rise rapidly near the onset of wetter climate conditions, then drop to near-modern rates well before the return to semi-arid conditions. Given that the averaging timescale of our samples is 8 to 46 kyr, to match the rapid observed rise in erosion rates with a 1D model of cosmogenic nuclide accumulation requires an increase in erosion rates several hundred times higher than the initial (pre-delta formation

  11. Chart of Nuclides from the National Nuclear Data Center (NNDC)

    DOE Data Explorer

    The Chart of Nuclides is a software product that allows users to search and plot nuclear structure and nuclear decay data interactively. The Chart of Nuclides was developed by the National Nuclear Data Center (NNDC). It provides an interface between web users and several databases containing nuclear structure, nuclear decay and some neutron-induced nuclear reaction information. Using the Chart of Nuclides, it is possible to search for nuclear level properties (energy, half-life, spin-parity), gamma-ray information (energy, intensity, multipolarity, coincidences),radiation information following nuclear decay (energy, intensity, dose), and neutron-induced reaction data from the BNL-325 book (thermal cross section and resonance integral). The information provided by the Chart of Nuclides can be seen in tables, level schemes and an interactive chart of nuclides. (From the Chart of Nuclides Description at http://www.nndc.bnl.gov/chart/help/index.jsp?product=chart)

  12. Mass measurements of exotic nuclides at SHIPTRAP

    SciTech Connect

    Block, M.; Ackermann, D.; Eliseev, S.; Herfurth, F.; Hessberger, F. P.; Hofmann, S.; Kluge, H.-J.; Maero, G.; Martin, A.; Mazzocco, M.; Mukherjee, M.; Quint, W.; Rahaman, S.; Rauth, C.; Rodriguez, D.; Scheidenberger, C.; Vorobjev, G.; Blaum, K.; Ferrer, R.; Weber, C.

    2007-05-22

    The Penning trap mass spectrometer SHIPTRAP is installed behind the velocity-filter SHIP at GSI for high-precision mass measurements of fusion-evaporation residues. To facilitate an efficient stopping of the reaction products a buffer gas stopping cell is utilized. In an investigation of neutron-deficient nuclides in the terbium-to-thulium region around A {approx_equal} 146, 18 new or improved mass values have been obtained, resulting in a more accurate determination of the proton drip line for holmium and thulium. With the present performance of SHIPTRAP, a first direct mass measurement of transuranium elements in the nobelium region is within reach.

  13. Mass Evaluation for Proton Rich Nuclides

    SciTech Connect

    Wang, M.; Audi, G.; Xu, X.; Pfeiffer, B.; Kondev, F. G.

    2011-11-30

    The Atomic mass evaluation (AME) provides the reliable resource for the values related to atomic masses. Since the publication of the latest version of AME in 2003, many developments for atomic mass determination have been done and important results changed significantly our knowledge. A preliminary version of AME was released in April 2011, and an official version is foreseen to be published in early 2013. The general status of AME is presented and some specific features of AME for proton-rich nuclides are discussed.

  14. Prediction of fiber composite mechanical behavior made simple. [using a rocket calculator

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1980-01-01

    The elastic properties and failure stresses of angleplied fiber composite laminates were determined using a pocket calculator. The procedure uses simple equations and appropriate graphs of elastic properties versus angle plies, and can handle all types of fiber composites including hybrids. The versatility and generality of the method is illustrated in several step-by-step numerical examples.

  15. Simplified Calculation Model and Experimental Study of Latticed Concrete-Gypsum Composite Panels

    PubMed Central

    Jiang, Nan; Ma, Shaochun

    2015-01-01

    In order to address the performance complexity of the various constituent materials of (dense-column) latticed concrete-gypsum composite panels and the difficulty in the determination of the various elastic constants, this paper presented a detailed structural analysis of the (dense-column) latticed concrete-gypsum composite panel and proposed a feasible technical solution to simplified calculation. In conformity with mechanical rules, a typical panel element was selected and divided into two homogenous composite sub-elements and a secondary homogenous element, respectively for solution, thus establishing an equivalence of the composite panel to a simple homogenous panel and obtaining the effective formulas for calculating the various elastic constants. Finally, the calculation results and the experimental results were compared, which revealed that the calculation method was correct and reliable and could meet the calculation needs of practical engineering and provide a theoretical basis for simplified calculation for studies on composite panel elements and structures as well as a reference for calculations of other panels. PMID:28793631

  16. Cosmogenic nuclides in early solar system materials

    NASA Astrophysics Data System (ADS)

    Bricker, Glynn Edward

    2009-09-01

    The overall goal of this research was to assess early solar system processes, particularly ancient proto-solar activity. This goal was addressed on two fronts. First, a model was developed to explain the provenance of now extinct radionuclides in early solar system materials, namely the refractory inclusions termed CAIs (Calcium-Aluminum-Inclusion) found in carbonaceous chondrites. As CAIs are believed to be the first solids to condense in the solar system and are also believed to have formed close to the proto-Sun, a model which explains the now extinct radionuclides found in CAIs constrains early solar system processes. Secondly, a series of measurements were performed on samples of the early solar system, namely chrondritic meteorites and the inclusions called chondrules, often contained within these meteorites. Chondrules, which are often a chief constituent of these meteorites, are believed to have originated close to the proto-Sun. As such, these materials should contain clues about solar processes at the beginning of the solar system. We propose a model for the incorporation of SLRs (short lived radionuclide) within CAIs in primitive carbonaceous meteorites. In this model SLRs are produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by proton fluxes higher than contemporary particle fluxes. These SLRs are entrained in the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system and is responsible for implantation of 10 Be, 14 C and other nuclides in lunar materials. We utilize contemporary experimental solar wind production rates for 10Be and 14 C and theoretical ancient production rates for 7 Be, 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, and 53 Mn. Using a ~ 10 5 enhancement in SEPs (solar energetic particles) and hence production rates in conjunction with an accepted refractory mass inflow rates close to the proto-Sun, we model

  17. Computer program FPIP-REV calculates fission product inventory for U-235 fission

    NASA Technical Reports Server (NTRS)

    Brown, W. S.; Call, D. W.

    1967-01-01

    Computer program calculates fission product inventories and source strengths associated with the operation of U-235 fueled nuclear power reactor. It utilizes a fission-product nuclide library of 254 nuclides, and calculates the time dependent behavior of the fission product nuclides formed by fissioning of U-235.

  18. Measurements of long-lived cosmogenic nuclides in returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Kohl, C. P.; Arnold, J. R.

    1989-01-01

    Measurements of long lived cosmic ray produced radionuclides have given much information on the histories and rates of surface evolution for meteorites, the Moon and the Earth. These nuclides can be equally useful in studying cometary histories and post nebular processing of cometary surfaces. The concentration of these nuclides depends on the orbit of the comet (cosmic ray intensity changes with distance from the sun), the depth of the sampling site in the comet surface, and the rate of continuous evolution of the surface (erosion rate of surface materials). If the orbital parameters and the sampling depth are known, production rates of cosmogenic nuclides can be fairly accurately calculated by theoretical models normalized to measurement on lunar surface materials and meteoritic samples. Due to the continuous evaporation of surface materials, it is expected that the long lived radioactivities will be undersaturated. Accurate measurements of the degree of undersaturation in nuclides of different half-lives allows for the determination of the rate of surface material loss over the last few million years.

  19. Bayesian estimation of a source term of radiation release with approximately known nuclide ratios

    NASA Astrophysics Data System (ADS)

    Tichý, Ondřej; Šmídl, Václav; Hofman, Radek

    2016-04-01

    We are concerned with estimation of a source term in case of an accidental release from a known location, e.g. a power plant. Usually, the source term of an accidental release of radiation comprises of a mixture of nuclide. The gamma dose rate measurements do not provide a direct information on the source term composition. However, physical properties of respective nuclide (deposition properties, decay half-life) can be used when uncertain information on nuclide ratios is available, e.g. from known reactor inventory. The proposed method is based on linear inverse model where the observation vector y arise as a linear combination y = Mx of a source-receptor-sensitivity (SRS) matrix M and the source term x. The task is to estimate the unknown source term x. The problem is ill-conditioned and further regularization is needed to obtain a reasonable solution. In this contribution, we assume that nuclide ratios of the release is known with some degree of uncertainty. This knowledge is used to form the prior covariance matrix of the source term x. Due to uncertainty in the ratios the diagonal elements of the covariance matrix are considered to be unknown. Positivity of the source term estimate is guaranteed by using multivariate truncated Gaussian distribution. Following Bayesian approach, we estimate all parameters of the model from the data so that y, M, and known ratios are the only inputs of the method. Since the inference of the model is intractable, we follow the Variational Bayes method yielding an iterative algorithm for estimation of all model parameters. Performance of the method is studied on simulated 6 hour power plant release where 3 nuclide are released and 2 nuclide ratios are approximately known. The comparison with method with unknown nuclide ratios will be given to prove the usefulness of the proposed approach. This research is supported by EEA/Norwegian Financial Mechanism under project MSMT-28477/2014 Source-Term Determination of Radionuclide Releases

  20. Analytical source term optimization for radioactive releases with approximate knowledge of nuclide ratios

    NASA Astrophysics Data System (ADS)

    Hofman, Radek; Seibert, Petra; Kovalets, Ivan; Andronopoulos, Spyros

    2015-04-01

    We are concerned with source term retrieval in the case of an accident in a nuclear power with off-site consequences. The goal is to optimize atmospheric dispersion model inputs using inverse modeling of gamma dose rate measurements (instantaneous or time-integrated). These are the most abundant type of measurements provided by various radiation monitoring networks across Europe and available continuously in near-real time. Usually, a source term of an accidental release comprises of a mixture of nuclides. Unfortunately, gamma dose rate measurements do not provide a direct information on the source term composition; however, physical properties of respective nuclides (deposition properties, decay half-life) can yield some insight. In the method presented, we assume that nuclide ratios are known at least approximately, e.g. from nuclide specific observations or reactor inventory and assumptions on the accident type. The source term can be in multiple phases, each being characterized by constant nuclide ratios. The method is an extension of a well-established source term inversion approach based on the optimization of an objective function (minimization of a cost function). This function has two quadratic terms: mismatch between model and measurements weighted by an observation error covariance matrix and the deviation of the solution from a first guess weighted by the first-guess error covariance matrix. For simplicity, both error covariance matrices are approximated as diagonal. Analytical minimization of the cost function leads to a liner system of equations. Possible negative parts of the solution are iteratively removed by the means of first guess error variance reduction. Nuclide ratios enter the problem in the form of additional linear equations, where the deviations from prescribed ratios are weighted by factors; the corresponding error variance allows us to control how strongly we want to impose the prescribed ratios. This introduces some freedom into the

  1. BRIEF REPORT: Systematics of alpha-decay half-life: new evaluations for alpha-emitter nuclides

    NASA Astrophysics Data System (ADS)

    Medeiros, E. L.; Rodrigues, M. M. N.; Duarte, S. B.; Tavares, O. A. P.

    2006-08-01

    A semiempirical model based on the quantum-mechanical tunnelling mechanism of alpha emission from nuclei has been used to systematize the alpha-decay half-lives of a set of 336 nuclides, comprising all the alpha-emitter nuclides whose T1/2α-data for ground-state to ground-state transitions of mutual angular momentum ell = 0 are known. With a minimum of data rejection (only ~5% of cases), the procedure has been successful in reproducing quite satisfactorily (within a factor of ~2) most of the cases (~80%) investigated. A few significant discrepancies found between measured and calculated results are analysed and discussed. Also reported is the prediction from the model for possible new alpha-emitter nuclides, namely 180W, 184Os and 228Ra, for which cases the calculated partial alpha-decay half-lives fall within the range of half-lives measurable by the current techniques.

  2. Prompt neutron multiplicities for the transplutonium nuclides

    SciTech Connect

    Holden, N.E.; Zucker, M.S.

    1985-01-01

    The direct determination of the average prompt neutron emission values is reviewed, and a method of comparing different sites of neutron emission multiplicity distribution values is described. Measured and recommended values are tabulated for these nuclides: /sup 241/Am, /sup 242/Am, /sup 242/Cm, /sup 243/Cm, /sup 244/Cm, /sup 246/Cm, /sup 247/Cm, /sup 248/Cm, /sup 250/Cm, /sup 245/Cm, /sup 249/Bk, /sup 246/Cf, /sup 249/Cf, /sup 250/Cf, /sup 252/Cf, /sup 254/Cf, /sup 251/Cf, /sup 253/Es, /sup 254/Es, /sup 244/Fm, /sup 246/Fm, /sup 255/Fm, /sup 252/No, /sup 254/Fm, /sup 256/Fm, /sup 257/Fm. 59 refs., 24 tabs. (LEW)

  3. Cosmogenic nuclides in football-sized rocks.

    NASA Technical Reports Server (NTRS)

    Wahlen, M.; Honda, M.; Imamura, M.; Fruchter, J. S.; Finkel, R. C.; Kohl, C. P.; Arnold, J. R.; Reedy, R. C.

    1972-01-01

    The activity of long- and short-lived isotopes in a series of samples from a vertical column through the center of rock 14321 was measured. Rock 14321 is a 9 kg fragmental rock whose orientation was photographically documented on the lunar surface. Also investigated was a sample from the lower portion of rock 14310, where, in order to study target effects, two different density fractions (mineral separates) were analyzed. A few nuclides in a sample from the comprehensive fines 14259 were measured. This material has been collected largely from the top centimeter of the lunar soil. The study of the deep samples of 14321 and 14310 provided values for the activity of isotopes at points where only effects produced by galactic cosmic rays are significant.

  4. Nuclide production in (very) small meteorites

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Nishiizumi, K.

    1986-01-01

    One of the most interesting open questions in the study of cosmic-ray effects in meteorites is the expected behavior of objects which are very small compared to the mean interaction length of primary galactic cosmic ray (GCR) particles. A reasonable limit might be a pre-atmospheric radius of 5 gram/cm(2), or 1.5 cm for chondrites. These are interesting for at least three reasons: (1) this is a limiting case for large objects, and can help us make better models; (2) this size is intermediate between usual meteorites and irradiated grams (spherules); and (3) these are the most likely objects to show solar cosmic ray (SCR) effects. Reedy (1984) has recently proposed a model for production by GCR of radioactive and stable nuclides in spherical meteorites. Very small objects are expected to deviate from this model in the direction of fewer secondary particles (larger spectral shape parameter), at all depths. The net effect will be significantly lower production of such low-energy products as Mn-53 and Al-26. The SCR production of these and other nuclides will be lower, too, because meteorite orbits extend typically out into the asteroid belt, and the mean SCR flux must fall off approximately as r(-2) with distance from the Sun. Kepler's laws insure that for such orbits most of the exposure time is spent near aphelion. None the less the equivalent mean exposure distance, R(exp), is slightly less than the semimajor axis A because of the weighting by R(-2). For the three meteorite orbits we have, R(exp) has a narrow range, from about 1.6 to 2.1 a.u. This is probably true for the great majority of meteorites.

  5. The spectrometric determination of the individual exposure rate for gamma nuclides from an environmental radiation detector

    SciTech Connect

    Young-Yong Ji; Kun Ho Chung; Wanno Lee; Doo-Won Park; Mun-Ja Kang

    2013-07-01

    For making the spectrometric determination of the exposure rate from the environment as well as the radioactive material more practical, an accurate calculation method of the individual exposure rate for the detected gamma nuclides from that spectrum should be suggested without the sophisticated calibration procedure. In this study, the calculation method for the individual exposure rate for detected gamma nuclides from a 3'x3' NaI(Tl) detector was suggested by introducing the concept of the dose rate spectroscopy and the peak-to-total ratio in the energy spectrum for the exposure rate, which means just a form of multiplied counts and the value of a G-factor in the spectrum. (authors)

  6. The Abundances of Nuclides Magnesium in the Atmospheres of Arcturus and Aldebaran

    NASA Astrophysics Data System (ADS)

    Gorbanjeva, T. I.; Kantzen, L. E.; Komarov, N. S.

    The abundances of nuclides magnesium in the atmospheres of Arcturus and Aldebaran thick and thin disks of Galaxy have been studied. The stars have various chromospheric activity. We used the new data on molecular constants of radiation for every electrically- vibrationally-rotating line of molecular system A2 Π-X2 Σ for MgH. The synthetic spectra were calculated. The values determined are generally close, but not equal, to the solar ratios.

  7. Measurement of radon/thoron and its daughter nuclides in room air.

    PubMed

    Suppian, R; Vegandraj, S; Kandaiya, S

    1992-07-01

    Pumping air through a soft tissue which acts as a membrane is a relatively easy and quick method to collect and measure radon/thoron and its daughter nuclides in air. Analysis of the activity of the radionuclides can be calculated using an alpha counter which has been calibrated. In this method the activity of radon/thoron cannot be separated from the activity of radionuclides already present in the aerosol or dust particles.

  8. Alkanes in Natural and Synthetic Petroleums: Comparison of Calculated and Actual Compositions.

    PubMed

    Friedel, R A; Sharkey, A G

    1963-03-22

    A similarity exists between the low molecular weight alkane isomers in crude oil and Fischer-Tropsch catalytic synthesis products. The composition of the C(4) through C(7) alkane isomers in a crude oil was calculated quantitatively with the equations previously used to calculate the alkane isomers in Fischer-Tropsch products. These results may have significance in ascertaining the origin of the volatile hydrocarbons in crude oils.

  9. Alpha-emitting nuclides in the marine environment

    NASA Astrophysics Data System (ADS)

    Pentreath, R. J.

    1984-06-01

    The occurrence of alpha-emitting nuclides and their daughter products in the marine environment continues to be a subject of study for many reasons. Those nuclides which occur naturally, in the uranium, thorium and actinium series, are of interest because of their value in determining the rates of geological and geochemical processes in the oceans. Studies of them address such problems as the determination of rates of transfer of particulate matter, deposition rates, bioturbation rates, and so on. Two of the natural alpha-series nuclides in which a different interest has been expressed are 210Po and 226Ra, because their concentrations in marine organisms are such that they contribute to a significant fraction of the background dose rates sustained both by the organisms themselves and by consumers of marine fish and shellfish. To this pool of naturally-occurring nuclides, human activities have added the transuranium nuclides, both from the atmospheric testing of nuclear devices and from the authorized discharges of radioactive wastes into coastal waters and the deep sea. Studies have therefore been made to understand the chemistry of these radionuclides in sea water, their association with sedimentary materials, and their accumulation by marine organisms, the last of these being of particular interest because the transuranics are essentially "novel" elements to the marine fauna and flora. The need to predict the long-term behaviour of these nuclides has, in turn, stimulated research on those naturally-occurring nuclides which may behave in a similar manner.

  10. Correction of in situ cosmogenic nuclide production rates for geomagnetic field intensity variations during the past 800,000 years

    NASA Astrophysics Data System (ADS)

    Masarik, Jozef; Frank, Martin; Schäfer, Jörg M.; Wieler, Rainer

    2001-09-01

    We present integrated relative production rates for cosmogenic nuclides in rock surfaces, which take into account reported variations of the geomagnetic field intensity during the past 800,000 yr. The calculations are based on the model simulating cosmic ray particle interactions with the Earth's atmosphere given by Masarik and Beer ["Simulation of particle fluxes and cosmogenic nuclide production in the Earth's atmosphere," J. Geophys. Res. 104(D10), 12099-12111, 1999]. Corrections are nearly independent on altitude between sea level and at least 5000 m. The correction factors are essentially identical for all stable and radioactive cosmogenic nuclides with half-lives longer than a few hundred thousand years. At the equator, integrated production rates for exposure ages between ˜40,000 to 800,000 yr are 10 to 12% higher than the present-day values, whereas at latitudes >40°, geomagnetic field intensity variations have hardly influenced in situ cosmogenic nuclide production. Correction factors for in situ 14C production rates differ from those of longer-lived nuclides. They are always smaller than ˜2% because the magnetic field intensity remained rather constant during the past ˜10 kyr, when the major fraction of the 14C extant today was produced.

  11. Thermodynamic method of calculating the effect of alloying additives on interphase interaction in composite materials

    NASA Technical Reports Server (NTRS)

    Tuchinsky, L. I.

    1986-01-01

    The effect of alloying additives to the matrix of a composite on the high temperature solubility rate of a single component fiber was analyzed thermodynamically. With an example of binary Ni alloys, with Group IV-VI transition metals reinforced with W fibers, agreement between the calculated and experimental data was demonstrated.

  12. Structure And Decay Of Neutron-Rich Nuclides In The 115 {<=} A {<=} 138 Mass Range And r-Process Nucleosynthesis

    SciTech Connect

    Walters, W.B.; Stoyer, M.A.; Shergur, J.; Hoteling, N.; Ressler, J.J.; Rikovska, J.; Kratz, K.-L.; Woehr, A.; Pfeiffer, B.; Arndt, O.; Mantica, P.F.; Tomlin, B.; Schatz, H.; Montes, F.; Brown, B.A.; Seweryniak, D.; Ravn, H.; Fedoseyev, V.; Koester, U.; Wu, C.Y.

    2005-04-05

    The structure and decay of neutron-rich r-process nuclides has been studied by a variety of means that take advantage of enhanced selectivity to permit identification of exotic nuclides. New level structures are presented for 134,135Sb along with data for Ag isomers and Cd yrast structures. Some of the properties measured play an important role in calculations of the yields of elements and isotopes produced in r-process nucleosynthesis that takes place at high temperature in the presence of large densities of neutrons.

  13. Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition

    SciTech Connect

    Landry, Guillaume; Reniers, Brigitte; Murrer, Lars; Lutgens, Ludy; Bloemen-Van Gurp, Esther; Pignol, Jean-Philippe; Keller, Brian; Beaulieu, Luc; Verhaegen, Frank

    2010-10-15

    Purpose: The objective of this work is to assess the sensitivity of Monte Carlo (MC) dose calculations to uncertainties in human tissue composition for a range of low photon energy brachytherapy sources: {sup 125}I, {sup 103}Pd, {sup 131}Cs, and an electronic brachytherapy source (EBS). The low energy photons emitted by these sources make the dosimetry sensitive to variations in tissue atomic number due to the dominance of the photoelectric effect. This work reports dose to a small mass of water in medium D{sub w,m} as opposed to dose to a small mass of medium in medium D{sub m,m}. Methods: Mean adipose, mammary gland, and breast tissues (as uniform mixture of the aforementioned tissues) are investigated as well as compositions corresponding to one standard deviation from the mean. Prostate mean compositions from three different literature sources are also investigated. Three sets of MC simulations are performed with the GEANT4 code: (1) Dose calculations for idealized TG-43-like spherical geometries using point sources. Radial dose profiles obtained in different media are compared to assess the influence of compositional uncertainties. (2) Dose calculations for four clinical prostate LDR brachytherapy permanent seed implants using {sup 125}I seeds (Model 2301, Best Medical, Springfield, VA). The effect of varying the prostate composition in the planning target volume (PTV) is investigated by comparing PTV D{sub 90} values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using {sup 103}Pd seeds (Model 2335, Best Medical). The effects of varying the adipose/gland ratio in the PTV and of varying the elemental composition of adipose and gland within one standard deviation of the assumed mean composition are investigated by comparing PTV D{sub 90} values. For (2) and (3), the influence of using the mass density from CT scans instead of unit mass density is also assessed. Results: Results from simulation (1) show that variations

  14. Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition.

    PubMed

    Landry, Guillaume; Reniers, Brigitte; Murrer, Lars; Lutgens, Ludy; Gurp, Esther Bloemen-Van; Pignol, Jean-Philippe; Keller, Brian; Beaulieu, Luc; Verhaegen, Frank

    2010-10-01

    The objective of this work is to assess the sensitivity of Monte Carlo (MC) dose calculations to uncertainties in human tissue composition for a range of low photon energy brachytherapy sources: 125I, 103Pd, 131Cs, and an electronic brachytherapy source (EBS). The low energy photons emitted by these sources make the dosimetry sensitive to variations in tissue atomic number due to the dominance of the photoelectric effect. This work reports dose to a small mass of water in medium D(w,m) as opposed to dose to a small mass of medium in medium D(m,m). Mean adipose, mammary gland, and breast tissues (as uniform mixture of the aforementioned tissues) are investigated as well as compositions corresponding to one standard deviation from the mean. Prostate mean compositions from three different literature sources are also investigated. Three sets of MC simulations are performed with the GEANT4 code: (1) Dose calculations for idealized TG-43-like spherical geometries using point sources. Radial dose profiles obtained in different media are compared to assess the influence of compositional uncertainties. (2) Dose calculations for four clinical prostate LDR brachytherapy permanent seed implants using 125I seeds (Model 2301, Best Medical, Springfield, VA). The effect of varying the prostate composition in the planning target volume (PTV) is investigated by comparing PTV D90 values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using 103Pd seeds (Model 2335, Best Medical). The effects of varying the adipose/gland ratio in the PTV and of varying the elemental composition of adipose and gland within one standard deviation of the assumed mean composition are investigated by comparing PTV D90 values. For (2) and (3), the influence of using the mass density from CT scans instead of unit mass density is also assessed. Results from simulation (1) show that variations in the mean compositions of tissues affect low energy brachytherapy dosimetry

  15. The Methodology of Calculation of Cutting Forces When Machining Composite Materials

    NASA Astrophysics Data System (ADS)

    Rychkov, D. A.; Yanyushkin, A. S.

    2016-08-01

    Cutting of composite materials has specific features and is different from the processing of metals. When this characteristic intense wear of the cutting tool. An important criterion in the selection process parameters composite processing is the value of the cutting forces, which depends on many factors and is determined experimentally, it is not always appropriate. The study developed a method of determining the cutting forces when machining composite materials and the comparative evaluation of the calculated and actual values of cutting forces. The methodology for calculating cutting forces into account specific features of the cutting tool and the extent of wear, the strength properties of the processed material and cutting conditions. Experimental studies conducted with fiberglass milling cutter equipped with elements of hard metal VK3M. The discrepancy between the estimated and the actual values of the cutting force is not more than 10%.

  16. Simulation of Galactic Cosmic Ray Interactions with Regolith: Implications for Cosmogenic Nuclide and Planetary Surface Studies

    NASA Astrophysics Data System (ADS)

    Bobias, S. G.; Dempsey, J. F.; Englert, P. A. J.; Drake, D. M.; Reedy, R. C.

    1992-07-01

    In planetary, asteroidal, and cometary surfaces the development of cosmic ray produced secondary particle cascades depends very much on the chemical composition. Most important is the abundance and distribution of neutron moderators, such as hydrogen and carbon. Their presence influences the distribution and flux of neutrons in extraterrestrial surfaces. Consequently, the distribution and activity of neutron produced cosmogenic nuclides, such as the neutron capture products ^36Cl (3.01x10^5y), ^41Ca (1.03x10^5y), ^59Ni (7.6x10^4 y) and ^60Co (5.271y), and the medium energy products such as ^22Na (2.605 y, from Al), ^26Al (7.4x10^5 y, from Si), ^53Mn (3.7x10^6, from Fe), etc., will be dependent on the development of the secondary neutron fluxes. Three thick target bombardments of artificial planetary surface soil (martian) [1,2,3] that measured the secondary particle cascade as well as surface neutron flux and leakage spectra were performed at the Los Alamos Meson Physics Facility's Weapons Neutron Research Laboratory. They provide data to study qualitatively and quantitatively the relation between bombarding galactic cosmic ray particles, the development of neutrons inside a surface and of neutrons emitted from a planetary surface. Past thick target bombardments were limited to only determining the secondary particle cascades or the emitted gamma radiation [4,5,6]. The experiments show that the second target, which was two times larger than the target for the first experiment, was holding more neutrons inside the target. The third irradiation utilized a polyethylene sheet in front of the second target to simulate the presence of water or ice on a planetary surface. Threshold monitors were placed both along the axis of symmetry and radially displaced axes. The monitors included foils of Ti, Mn, Fe, Co, Ni, and Au. The induced radioactivity was measured at Los Alamos by conventional gamma-ray spectrometry approximately 48 hours at the end of irradiation. Both the

  17. The even-odd systematics in R-process nuclide abundances

    NASA Technical Reports Server (NTRS)

    Marti, K.; Suess, H. E.

    1988-01-01

    The paper reports and discusses solar system N(R) abundances for nuclides A greater than 70, obtained as differences between measured solar system abundances and calculated S-process contributions. The abundance peak at A of about 163 in the rare earth element region reveals properties which are similar to those of the R-process peaks corresponding to magic neutron numbers N = 82 and N = 126. Systematic differences in the N(R) abundances of even-A and odd-A nuclides are restricted to specific mass regions. It is concluded that these differences are most probably related to the properties of nuclear species during beta(-) decay to the stability valley.

  18. Interplay of direct and compound-nucleus mechanisms in neutron capture by light nuclides

    SciTech Connect

    Raman, S.; Kahane, S.; Lynn, J.E.

    1988-01-01

    The authors discuss the direct-capture theory pertaining to primary electric-dipole (E1) transitions following slow-neutron capture. For approximately 20 light nuclides that we have studied, estimates of direct-capture cross sections using optical-model potentials with physically realistic parameters are in reasonable agreement with the data. Minor disagreements that exist are consistent with extrapolations to light nuclides of generally accepted formulations of compound-nucleus capture. In dealing with nuclei soft to vibrations, we have considered the possible effects of coupling of the collective motion with the optical potential in the framework of R-matrix theory. In such cases, we find that the inclusion of inelastic channels results in systematic changes in the calculated cross sections.

  19. Nuclide analysis in high burnup fuel samples irradiated in Vandellós 2

    NASA Astrophysics Data System (ADS)

    Zwicky, H. U.; Low, J.; Granfors, M.; Alejano, C.; Conde, J. M.; Casado, C.; Sabater, J.; Lloret, M.; Quecedo, M.; Gago, J. A.

    2010-07-01

    In the framework of a high burnup fuel demonstration programme, rods with an enrichment of 4.5% 235U were operated to a rod average burnup of about 70 MWd/kgU in the Spanish Vandellós 2 pressurised water reactor. The rods were sent to hot cells and used for different research projects. This paper describes the isotopic composition measurements performed on samples of those rods, and the analysis of the measurement results based on comparison against calculated values. The fraction and composition of fission gases released to the rod free volume was determined for two of the rods. About 8% of Kr and Xe produced by fission were released. From the isotopic composition of the gases, it could be concluded that the gases were not preferentially released from the peripheral part of the fuel column. Local burnup and isotopic content of gamma emitting nuclides were determined by quantitatively evaluating axial gamma scans of the full rods. Nine samples were cut at different axial levels from three of the rods and analysed in two campaigns. More than 50 isotopes of 16 different elements were assessed, most of them by Inductively Coupled Plasma Mass Spectrometry after separation with High Performance Liquid Chromatography. In general, these over 400 data points gave a consistent picture of the isotopic content of irradiated fuel as a function of burnup. Only in a few cases, the analysis provided unexpected results that seem to be wrong, in most cases due to unidentified reasons. Sample burnup analysis was performed by comparing experimental isotopic abundances of uranium and plutonium composition as well as neodymium isotopic concentrations with corresponding CASMO based data. The results were in agreement with values derived independently from gamma scanning and from core design data and plant operating records. Measured isotope abundances were finally assessed using the industry standard SAS2H sequence of the SCALE code system. This exercise showed good agreement between

  20. Inventory simulation tools: Separating nuclide contributions to radiological quantities

    NASA Astrophysics Data System (ADS)

    Gilbert, Mark R.; Fleming, Michael; Sublet, Jean-Christophe

    2017-09-01

    The activation response of a material is a primary factor considered when evaluating its suitability for a nuclear application. Various radiological quantities, such as total (becquerel) activity, decay heat, and γ dose, can be readily predicted via inventory simulations, which numerically evolve in time the composition of a material under exposure to neutron irradiation. However, the resulting data sets can be very complex, often necessarily resulting in an over-simplification of the results - most commonly by just considering total response metrics. A number of different techniques for disseminating more completely the vast amount of data output from, in particular, the FISPACT-II inventory code system, including importance diagrams, nuclide maps, and primary knock-on atom (PKA) spectra, have been developed and used in scoping studies to produce database reports for the periodic table of elements. This paper introduces the latest addition to this arsenal - standardised and automated plotting of the time evolution in a radiological quantity for a given material separated by contributions from dominant radionuclides. Examples for relevant materials under predicted fusion reactor conditions, and for bench-marking studies against decay-heat measurements, demonstrate the usefulness and power of these radionuclide-separated activation plots. Note to the reader: the pdf file has been changed on September 22, 2017.

  1. (The fate of nuclides in natural water systems)

    SciTech Connect

    Turekian, K.K. . Dept. of Geology and Geophysics)

    1989-01-01

    Our research at Yale on the fate of nuclides in natural water systems has three components to it: the study of the atmospheric precipitation of radionuclides and other chemical species; the study of the behavior of natural radionuclides in groundwater and hydrothermal systems; and understanding the controls on the distribution of radionuclides and stable nuclides in the marine realm. In this section a review of our progress in each of these areas is presented.

  2. Comparisons of Neutron Cross Sections and Isotopic Composition Calculations for Fission-Product Evaluations

    NASA Astrophysics Data System (ADS)

    Kim, Do Heon; Gil, Choong-Sup; Chang, Jonghwa; Lee, Yong-Deok

    2005-05-01

    The neutron absorption cross sections for 18 fission products evaluated within the framework of the KAERI (Korea Atomic Energy Research Institute)-BNL (Brookhaven National Laboratory) international collaboration have been compared with ENDF/B-VI.7. Also, the influence of the new evaluations on the isotopic composition calculations of the fission products has been estimated through the OECD/NEA burnup credit criticality benchmarks (Phase 1B) and the LWR/Pu recycling benchmarks. These calculations were performed by WIMSD-5B with the 69-group libraries prepared from three evaluated nuclear data libraries: ENDF/B-VI.7, ENDF/B-VI.8 including the new evaluations in the resonance region covering the thermal region, and the expected ENDF/B-VII including those in the upper resonance region up to 20 MeV. For Xe-131, the composition calculated with ENDF/B-VI.8 shows a maximum difference of 5.02% compared to ENDF/B-VI.7. However, the isotopic compositions of all the fission products calculated with the expected ENDF/B-VII show no differences when compared to ENDF/B-VI.7 for the thermal reactor benchmark cases.

  3. Scaling in situ cosmogenic nuclide production rates using analytical approximations to atmospheric cosmic-ray fluxes

    NASA Astrophysics Data System (ADS)

    Lifton, Nathaniel; Sato, Tatsuhiko; Dunai, Tibor J.

    2014-01-01

    Several models have been proposed for scaling in situ cosmogenic nuclide production rates from the relatively few sites where they have been measured to other sites of interest. Two main types of models are recognized: (1) those based on data from nuclear disintegrations in photographic emulsions combined with various neutron detectors, and (2) those based largely on neutron monitor data. However, stubborn discrepancies between these model types have led to frequent confusion when calculating surface exposure ages from production rates derived from the models. To help resolve these discrepancies and identify the sources of potential biases in each model, we have developed a new scaling model based on analytical approximations to modeled fluxes of the main atmospheric cosmic-ray particles responsible for in situ cosmogenic nuclide production. Both the analytical formulations and the Monte Carlo model fluxes on which they are based agree well with measured atmospheric fluxes of neutrons, protons, and muons, indicating they can serve as a robust estimate of the atmospheric cosmic-ray flux based on first principles. We are also using updated records for quantifying temporal and spatial variability in geomagnetic and solar modulation effects on the fluxes. A key advantage of this new model (herein termed LSD) over previous Monte Carlo models of cosmogenic nuclide production is that it allows for faster estimation of scaling factors based on time-varying geomagnetic and solar inputs. Comparing scaling predictions derived from the LSD model with those of previously published models suggest potential sources of bias in the latter can be largely attributed to two factors: different energy responses of the secondary neutron detectors used in developing the models, and different geomagnetic parameterizations. Given that the LSD model generates flux spectra for each cosmic-ray particle of interest, it is also relatively straightforward to generate nuclide-specific scaling

  4. Nuclear Properties and Decay Data Chart of Nuclides.

    SciTech Connect

    OSORIO, V. B.

    2008-04-04

    Version 00 NUCHART displays nuclear decay data graphically on a PC and, includes a search routine for assigning gamma-ray energies to radionuclides. The numerical data included in NUCHART were taken from the online database "NUDAT" Version of March 1994. The following information is presented: (1) Nuclide information: for each nuclide, abundance, mass excess, (main) decay mode, half-life and uncertainty, branching ratio, decay Q; (2) decay radiation: for each nuclide, tables of radiation energy, intensity and equivalent dose for the 5 most intense decay radiations of beta+, beta-, conversion electrons, gammas, alphas and x-rays, including electron Augers; (3) adopted gammas: for each nuclide, table containing energy, relative intensity, energy level of the main gamma lines and year of publication in Nuclear Data Sheets; (4) search gamma energies: for a specified interval of gamma energies all know gamma lines and their nuclides are displayed; the database contains 132,000 gamma lines; (5) a search mode by specific nuclide is also available. For the latest data and online tools for viewing the data, see NuDat 2.4 on the NNDC and IAEA NDS websites: http://www.nndc.bnl.gov/ and http://www-nds.iaea.org/.

  5. Dielectric permittivity calculation of composites based on electrospun barium titanate fibers

    NASA Astrophysics Data System (ADS)

    Ávila, H. A.; Reboredo, M. M.; Parra, R.; Castro, M. S.

    2015-04-01

    On the basis of theoretical predictions and experimental results, an empirical method using upper bound equation of the rule of mixtures (ROM) is reported to predict the dielectric permittivity of barium titanate nanofibers. In addition, composites with low volume fraction of BaTiO3 fiber layers embedded in epoxy resin were prepared and characterized. The relative permittivities of composites with perpendicular and parallel configurations, with respect to the electrodes, were calculated by means of the ROM model. The predicted permittivities matched precisely the obtained experimental values.

  6. Algorithm Improvement Program Nuclide Identification Algorithm Scoring Criteria And Scoring Application - DNDO.

    SciTech Connect

    Enghauser, Michael

    2015-02-01

    The goal of the Domestic Nuclear Detection Office (DNDO) Algorithm Improvement Program (AIP) is to facilitate gamma-radiation detector nuclide identification algorithm development, improvement, and validation. Accordingly, scoring criteria have been developed to objectively assess the performance of nuclide identification algorithms. In addition, a Microsoft Excel spreadsheet application for automated nuclide identification scoring has been developed. This report provides an overview of the equations, nuclide weighting factors, nuclide equivalencies, and configuration weighting factors used by the application for scoring nuclide identification algorithm performance. Furthermore, this report presents a general overview of the nuclide identification algorithm scoring application including illustrative examples.

  7. Algorithm improvement program nuclide identification algorithm scoring criteria and scoring application.

    SciTech Connect

    Enghauser, Michael

    2016-02-01

    The goal of the Domestic Nuclear Detection Office (DNDO) Algorithm Improvement Program (AIP) is to facilitate gamma-radiation detector nuclide identification algorithm development, improvement, and validation. Accordingly, scoring criteria have been developed to objectively assess the performance of nuclide identification algorithms. In addition, a Microsoft Excel spreadsheet application for automated nuclide identification scoring has been developed. This report provides an overview of the equations, nuclide weighting factors, nuclide equivalencies, and configuration weighting factors used by the application for scoring nuclide identification algorithm performance. Furthermore, this report presents a general overview of the nuclide identification algorithm scoring application including illustrative examples.

  8. Production and Recoil Loss of Cosmogenic Nuclides in Presolar Grains

    NASA Astrophysics Data System (ADS)

    Trappitsch, Reto; Leya, Ingo

    2016-05-01

    Presolar grains are small particles that condensed in the vicinity of dying stars. Some of these grains survived the voyage through the interstellar medium (ISM) and were incorporated into meteorite parent bodies at the formation of the Solar System. An important question is when these stellar processes happened, i.e., how long presolar grains were drifting through the ISM. While conventional radiometric dating of such small grains is very difficult, presolar grains are irradiated with galactic cosmic rays (GCRs) in the ISM, which induce the production of cosmogenic nuclides. This opens the possibility to determine cosmic-ray exposure (CRE) ages, i.e., how long presolar grains were irradiated in the ISM. Here, we present a new model for the production and loss of cosmogenic 3He, 6,7Li, and 21,22Ne in presolar SiC grains. The cosmogenic production rates are calculated using a state-of-the-art nuclear cross-section database and a GCR spectrum in the ISM consistent with recent Voyager data. Our findings are that previously measured 3He and 21Ne CRE ages agree within the (sometimes large) 2σ uncertainties and that the CRE ages for most presolar grains are smaller than the predicted survival times. The obtained results are relatively robust since interferences from implanted low-energy GCRs into the presolar SiC grains and/or from cosmogenic production within the meteoroid can be neglected.

  9. PRODUCTION CONSIDERATIONS FOR THE CLASSICAL PET NUCLIDES.

    SciTech Connect

    FINN,R.; SCHLYER,D.

    2001-06-25

    Nuclear Medicine is the specialty of medical imaging, which utilizes a variety of radionuclides incorporated into specific compounds for diagnostic imaging and therapeutic applications. During recent years, research efforts associated with this discipline have concentrated on the decay characteristics of particular radionuclides and the design of unique radiolabeled tracers necessary to achieve time-dependent molecular images. The specialty is expanding with specific Positron emission tomography (PET) and SPECT radiopharmaceuticals allowing for an extension from functional process imaging in tissue to pathologic processes and nuclide directed treatments. PET is an example of a technique that has been shown to yield the physiologic information necessary for clinical oncology diagnoses based upon altered tissue metabolism. Most PET drugs are currently produced using a cyclotron at locations that are in close proximity to the hospital or academic center at which the radiopharmaceutical will be administered. In November 1997, a law was enacted called the Food and Drug Administration Modernization Act of 1997 which directed the Food and Drug Administration (FDA) to establish appropriate procedures for the approval of PET drugs in accordance with section 505 of the Federal Food, Drug, and Cosmetic Act and to establish current good manufacturing practice requirements for such drugs. At this time the FDA is considering adopting special approval procedures and cGMP requirements for PET drugs. The evolution of PET radiopharmaceuticals has introduced a new class of ''drugs'' requiring production facilities and product formulations that must be closely aligned with the scheduled clinical utilization. The production of the radionuclide in the appropriate synthetic form is but one critical component in the manufacture of the finished radiopharmaceutical.

  10. Approach for validating actinide and fission product compositions for burnup credit criticality safety analyses

    DOE PAGES

    Radulescu, Georgeta; Gauld, Ian C.; Ilas, Germina; ...

    2014-11-01

    This paper describes a depletion code validation approach for criticality safety analysis using burnup credit for actinide and fission product nuclides in spent nuclear fuel (SNF) compositions. The technical basis for determining the uncertainties in the calculated nuclide concentrations is comparison of calculations to available measurements obtained from destructive radiochemical assay of SNF samples. Probability distributions developed for the uncertainties in the calculated nuclide concentrations were applied to the SNF compositions of a criticality safety analysis model by the use of a Monte Carlo uncertainty sampling method to determine bias and bias uncertainty in effective neutron multiplication factor. Application ofmore » the Monte Carlo uncertainty sampling approach is demonstrated for representative criticality safety analysis models of pressurized water reactor spent fuel pool storage racks and transportation packages using burnup-dependent nuclide concentrations calculated with SCALE 6.1 and the ENDF/B-VII nuclear data. Furthermore, the validation approach and results support a recent revision of the U.S. Nuclear Regulatory Commission Interim Staff Guidance 8.« less

  11. Approach for validating actinide and fission product compositions for burnup credit criticality safety analyses

    SciTech Connect

    Radulescu, Georgeta; Gauld, Ian C.; Ilas, Germina; Wagner, John C.

    2014-11-01

    This paper describes a depletion code validation approach for criticality safety analysis using burnup credit for actinide and fission product nuclides in spent nuclear fuel (SNF) compositions. The technical basis for determining the uncertainties in the calculated nuclide concentrations is comparison of calculations to available measurements obtained from destructive radiochemical assay of SNF samples. Probability distributions developed for the uncertainties in the calculated nuclide concentrations were applied to the SNF compositions of a criticality safety analysis model by the use of a Monte Carlo uncertainty sampling method to determine bias and bias uncertainty in effective neutron multiplication factor. Application of the Monte Carlo uncertainty sampling approach is demonstrated for representative criticality safety analysis models of pressurized water reactor spent fuel pool storage racks and transportation packages using burnup-dependent nuclide concentrations calculated with SCALE 6.1 and the ENDF/B-VII nuclear data. Furthermore, the validation approach and results support a recent revision of the U.S. Nuclear Regulatory Commission Interim Staff Guidance 8.

  12. Benchmark data for validating irradiated fuel compositions used in criticality calculations

    SciTech Connect

    Bierman, S.R.; Talbert, R.J.

    1994-10-01

    To establish criticality safety margins utilizing burnup credit in the storage and transport of spent reactor fuels requires a knowledge of the uncertainty in the calculated fuel composition used in making the reactivity assessment. To provide data for validating such calculated burnup fuel compositions, radiochemical assays have been obtained as part of the United States Department of Energy From-Reactor Cask Development Program. Assay results and associated operating histories on the initial three samples analyzed in this effort are presented. The three samples were taken from different axial regions of a Pressurized Water Reactor fuel rod and represent radiation exposures of about 37, 27, and 44 GWd/MTU. The data are presented in a benchmark type format to facilitate identification/referencing and computer code input.

  13. Calculation of subunit stoichiometry of large, multisubunit proteins from amino acid compositions.

    PubMed

    Kapp, O H; Qabar, A N; Vinogradov, S N

    1990-01-01

    The subunit stoichiometry of a large, multisubunit protein can be determined from the molar amino acid compositions (i amino acids) of the protein and its subunits. The number of copies of the subunits (1, 2, ... j) is calculated by solving all possible combinations of simultaneous equations in j unknowns (i!/j!(i - j)!). Calculations carried out using the published amino acid compositions determined by analysis and the compositions calculated from the sequences for two proteins of known stoichiometry provided the following results: Escherichia coli aspartate transcarbamoylase (R6C6, Mr = 307.5 kDa), R = 5.6 to 6.6 and C = 5.8 to 6.3, and spinach ribulose-bisphosphate carboxylase (L8S8, Mr = 535 kDa), L = 7.3 to 9.1 and S = 5.6 to 10.6. Calculations were also carried out with the amino acid compositions of two much larger proteins, the E. coli pyruvate dehydrogenase complex, Mr = 5280 kDa, subunits E1 (99.5 kDa), E2 (66 kDa), and E3 (50.6 kDa), and the extracellular hemoglobin of Lumbricus terrestris, Mr = 3760 kDa, subunits M (17 kDa), D1 (31 kDa), D2 (37 kDa), and T (51 kDa); the results for PDHase were E1 = 20 to 24, E2 = 18 to 31, E3 = 21 to 33 and those for Lumbricus hemoglobin were M = 34 to 46, D1 = 13 to 19, D2 = 13 to 18, and T = 34 to 36. Although the sample standard deviations of the mean values are generally high, the proposed method works surprisingly well for the two smaller proteins and provides physically reasonable results for the two larger proteins.

  14. Initial Test Determination of Cosmogenic Nuclides in Magnetite

    NASA Astrophysics Data System (ADS)

    Matsumura, H.; Caffee, M. W.; Nagao, K.; Nishiizumi, K.

    2014-12-01

    Long-lived radionuclides, such as 10Be, 26Al, and 36Cl, are produced by cosmic rays in surficial materials on Earth, and used for determinations of cosmic-ray exposure ages and erosion rates. Quartz and limestone are routinely used as the target minerals for these geomorphological studies. Magnetite also contains target elements that produce abundant cosmogenic nuclides when exposed to the cosmic rays. Magnetite has several notable merits that enable the measurement of cosmogenic nuclides: (1) the target elements for production of cosmogenic nuclides in magnetite comprise the dominant mineral form of magnetite, Fe3O4; (2) magnetite can be easily isolated, using a magnet, after rock milling; (3) multiple cosmogenic nuclides are produced by exposure of magnetite to cosmic-ray secondaries; and (4) cosmogenic nuclides produced in the rock containing the magnetite, but not within the magnetite itself, can be separated using nitric acid and sodium hydroxide leaches. As part of this initial study, magnetite was separated from a basaltic sample collected from the Atacama Desert in Chili (2,995 m). Then Be, Al, Cl, Ca, and Mn were separated from ~2 g of the purified magnetite. We measured cosmogenic 10Be, 26Al, and 36Cl concentrations in the magnetite by accelerator mass spectrometry at PRIME Lab, Purdue University. Cosmogenic 3He and 21Ne concentrations of aliquot of the magnetite were measured by mass spectrometry at the University of Tokyo. We also measured the nuclide concentrations from magnetite collected from a mine at Ishpeming, Michigan as a blank. The 10Be and 36Cl concentrations as well as 3He concentration produce concordant cosmic ray exposure ages of ~0.4 Myr for the Atacama basalt. However, observed high 26Al and 21Ne concentrations attribute to those nuclides incorporation from silicate impurity.

  15. A finite element method for shear stresses calculation in composite blade models

    NASA Astrophysics Data System (ADS)

    Paluch, B.

    1991-09-01

    A finite-element method is developed for accurately calculating shear stresses in helicopter blade models, induced by torsion and shearing forces. The method can also be used to compute the equivalent torsional stiffness of the section, their transverse shear coefficient, and the position of their center of torsion. A grid generator method which is a part of the calculation program is also described and used to discretize the sections quickly and to condition the grid data reliably. The finite-element method was validated on a few sections composed of isotropic materials and was then applied to a blade model sections made of composite materials. Good agreement was obtained between the calculated and experimental data.

  16. Experimental Determination and Theoretical Calculation of the Eutectic Composition of Cefuroxime Axetil Diastereomers.

    PubMed

    Dalal, Namita; Buckner, Ira S; Wildfong, Peter L D

    2017-02-22

    Cefuroxime axetil (CFA), an ester prodrug of cefuroxime exists as a pair of diastereoemers, namely isomer A and isomer B. To enable phase diagram construction, crystallization of the diastereomers of CFA from the commercially available amorphous drug substance was carried out. Isomer A was separated with a purity approaching 100% whereas the maximum purity of isomer B was 85% as confirmed by solution state proton NMR spectroscopy. The crystalline forms of isomer A and isomer B were confirmed as forms AI and BI, respectively, based on differential scanning calorimetry (DSC) analysis and powder X-ray diffraction. DSC analysis was used to observe the melting behavior of different diastereomer mixture compositions. The binary solid-liquid phase diagram for mixture compositions ranging from 0 to 85% w/w isomer B indicated the formation of a eutectic mixture having a melting temperature of 124.7 ± 0.4°C and a composition of 75% w/w (+/-5% wt.) isomer B. The eutectic composition was calculated using an index based on the van't Hoff equation for melting point depression and was found to be 75% isomer B and 25% isomer A. As CFA is present in commercial preparations as a mixture of diastereomers, the formation of a eutectic mixture between the diastereomers may impact the solubility and stability of the commercial product. Eutectic formation can be explained on the basis of the chemical similarity of diastereomers that favor miscibility in the liquid state.

  17. Variable temperature effects on release rates of readily soluble nuclides

    SciTech Connect

    Kim, C.-L.; Light, W.B.; Lee, W.W.-L.; Chambre, P.L.; Pigford, T.H.; Lawrence Berkeley Lab., CA )

    1988-09-01

    In this paper we study the effect of temperature on the release rate of readily soluble nuclides, as affected by a time-temperature dependent diffusion coefficient. In this analysis ground water fills the voids in the waste package at t = 0 and one percent of the inventories of cesium and iodine are immediately dissolved into the void water. Mass transfer resistance of partly failed container and cladding is conservatively neglected. The nuclides move through the void space into the surrounding rock under a concentration gradient. We use an analytic solution to compute the nuclide concentration in the gap or void, and the mass flux rate into the porous rock. 8 refs., 4 figs.

  18. Granular composites containing ``micro-onions,'' permeability, and permittivity calculated for application to microwave absorbers

    NASA Astrophysics Data System (ADS)

    Abe, M.; Kuroda, J.; Matsumoto, M.

    2002-05-01

    The formula for the effective permeability <μ> (or permittivity <ɛ>) is derived, based on the Maxwell Garnett approximation, for the granular composites having "micro-onions" (micron-meter-sized, multifold core-shell structured particles) dispersed in matrices. We calculated <μ> and <ɛ> up to 3 GHz for the composites in which micro-onions of threefold [i.e., air/(silica+air)/NiZn-ferrite or water/(silica+water)/NiZn-ferrite] structure are dispersed in a Fe/silicon-rubber matrix. Introducing the micro-onions into the Fe/silicon-rubber matrix improves the wave absorber characteristics, increasing absorption and decreasing reflection, at 0.5-3 GHz. Confining the magnetic substance to the outermost shell layers increases the natural ferromagnetic resonance frequency, thus enhancing permeability at high frequencies. It also facilitates fabrication of lightweight electromagnetic wave absorbers, and suppresses eddy current loss in case the magnetic substance is a metal.

  19. Effect of composition on antiphase boundary energy in Ni3Al based alloys: Ab initio calculations

    NASA Astrophysics Data System (ADS)

    Gorbatov, O. I.; Lomaev, I. L.; Gornostyrev, Yu. N.; Ruban, A. V.; Furrer, D.; Venkatesh, V.; Novikov, D. L.; Burlatsky, S. F.

    2016-06-01

    The effect of composition on the antiphase boundary (APB) energy of Ni-based L 12-ordered alloys is investigated by ab initio calculations employing the coherent potential approximation. The calculated APB energies for the {111} and {001} planes reproduce experimental values of the APB energy. The APB energies for the nonstoichiometric γ' phase increase with Al concentration and are in line with the experiment. The magnitude of the alloying effect on the APB energy correlates with the variation of the ordering energy of the alloy according to the alloying element's position in the 3 d row. The elements from the left side of the 3 d row increase the APB energy of the Ni-based L 12-ordered alloys, while the elements from the right side slightly affect it except Ni. The way to predict the effect of an addition on the {111} APB energy in a multicomponent alloy is discussed.

  20. Cratering and cosmogenic nuclides. [as function of depth in regolith

    NASA Technical Reports Server (NTRS)

    Blake, M. L.; Wasserburg, G. J.

    1975-01-01

    A simple probabilistic model was constructed for the average value of a cosmogenic nuclide as a function of depth in a regolith. An arbitrary function was chosen for the size distribution of craters. The resulting integro-differential equation was found to reduce in limiting cases to the marching equation with a characteristic residence time and to the diffusion equation. The regolith diffusion constant is shown to be a simple integral of the cratering rate weighted by geometrical terms. This formal treatment provides a direct and general connection between cosmogenic nuclides and cratering rates and crater population in a simple analytical form. The validity of this model remains to be tested.

  1. Constraints on the composition of the Earth's core from ab initio calculations

    NASA Astrophysics Data System (ADS)

    Alfè, D.; Gillan, M. J.; Price, G. D.

    2000-05-01

    Knowledge of the composition of the Earth's core is important for understanding its melting point and therefore the temperature at the inner-core boundary and the temperature profile of the core and mantle. In addition, the partitioning of light elements between solid and liquid, as the outer core freezes at the inner-core boundary, is believed to drive compositional convection, which in turn generates the Earth's magnetic field. It is generally accepted that the liquid outer core and the solid inner core consist mainly of iron. The outer core, however, is also thought to contain a significant fraction of light elements, because its density-as deduced from seismological data and other measurements-is 6-10 per cent less than that estimated for pure liquid iron. Similar evidence indicates a smaller but still appreciable fraction of light elements in the inner core. The leading candidates for the light elements present in the core are sulphur, oxygen and silicon. Here we obtain a constraint on core composition derived from ab initio calculation of the chemical potentials of light elements dissolved in solid and liquid iron. We present results for the case of sulphur, which provide strong evidence against the proposal that the outer core is close to being a binary iron-sulphur mixture.

  2. Mid-Pleistocene cosmogenic minimum-age limits for pre-Wisconsinan glacial surfaces in southwestern Minnesota and southern Baffin Island: A multiple nuclide approach

    USGS Publications Warehouse

    Bierman, P.R.; Marsella, K.A.; Patterson, Chris; Davis, P.T.; Caffee, M.

    1999-01-01

    Paired 10Be and 26Al analyses (n = 14) indicate that pre-Wisconsinan, glaciated bedrock surfaces near the northern (Baffin Island) and southern (Minnesota) paleo-margins of the Laurentide Ice Sheet have long and complex histories of cosmic-ray exposure, including significant periods of partial or complete shielding from cosmic rays. Using the ratio, 26Al/10Be, we calculate that striated outcrops of Sioux Quartzite in southwestern Minnesota (southern margin) were last overrun by ice at least 500,000 years ago. Weathered bedrock tors on the once-glaciated uplands of Baffin Island (northern margin) are eroding no faster than 1.1 m Myr-1, the equivalent of at least 450,000 years of surface and near-surface exposure. Our data demonstrate that exposure ages and erosion rates calculated from single nuclides can underestimate surface stability dramatically because any intermittent burial, and the resultant lowering of nuclide production rates and nuclide abundances, will remain undetected.

  3. Shielding and activity estimator for template-based nuclide identification methods

    DOEpatents

    Nelson, Karl Einar

    2013-04-09

    According to one embodiment, a method for estimating an activity of one or more radio-nuclides includes receiving one or more templates, the one or more templates corresponding to one or more radio-nuclides which contribute to a probable solution, receiving one or more weighting factors, each weighting factor representing a contribution of one radio-nuclide to the probable solution, computing an effective areal density for each of the one more radio-nuclides, computing an effective atomic number (Z) for each of the one more radio-nuclides, computing an effective metric for each of the one or more radio-nuclides, and computing an estimated activity for each of the one or more radio-nuclides. In other embodiments, computer program products, systems, and other methods are presented for estimating an activity of one or more radio-nuclides.

  4. Monte Carlo calculation based on hydrogen composition of the tissue for MV photon radiotherapy.

    PubMed

    Demol, Benjamin; Viard, Romain; Reynaert, Nick

    2015-09-01

    The purpose of this study was to demonstrate that Monte Carlo treatment planning systems require tissue characterization (density and composition) as a function of CT number. A discrete set of tissue classes with a specific composition is introduced. In the current work we demonstrate that, for megavoltage photon radiotherapy, only the hydrogen content of the different tissues is of interest. This conclusion might have an impact on MRI-based dose calculations and on MVCT calibration using tissue substitutes. A stoichiometric calibration was performed, grouping tissues with similar atomic composition into 15 dosimetrically equivalent subsets. To demonstrate the importance of hydrogen, a new scheme was derived, with correct hydrogen content, complemented by oxygen (all elements differing from hydrogen are replaced by oxygen). Mass attenuation coefficients and mass stopping powers for this scheme were calculated and compared to the original scheme. Twenty-five CyberKnife treatment plans were recalculated by an in-house developed Monte Carlo system using tissue density and hydrogen content derived from the CT images. The results were compared to Monte Carlo simulations using the original stoichiometric calibration. Between 300 keV and 3 MeV, the relative difference of mass attenuation coefficients is under 1% within all subsets. Between 10 keV and 20 MeV, the relative difference of mass stopping powers goes up to 5% in hard bone and remains below 2% for all other tissue subsets. Dose-volume histograms (DVHs) of the treatment plans present no visual difference between the two schemes. Relative differences of dose indexes D98, D95, D50, D05, D02, and Dmean were analyzed and a distribution centered around zero and of standard deviation below 2% (3σ) was established. On the other hand, once the hydrogen content is slightly modified, important dose differences are obtained. Monte Carlo dose planning in the field of megavoltage photon radiotherapy is fully achievable using

  5. Monte Carlo calculation based on hydrogen composition of the tissue for MV photon radiotherapy.

    PubMed

    Demol, Benjamin; Viard, Romain; Reynaert, Nick

    2015-09-08

    The purpose of this study was to demonstrate that Monte Carlo treatment planning systems require tissue characterization (density and composition) as a function of CT number. A discrete set of tissue classes with a specific composition is introduced. In the current work we demonstrate that, for megavoltage photon radiotherapy, only the hydrogen content of the different tissues is of interest. This conclusion might have an impact on MRI-based dose calculations and on MVCT calibration using tissue substitutes. A stoichiometric calibration was performed, grouping tissues with similar atomic composition into 15 dosimetrically equivalent subsets. To demonstrate the importance of hydrogen, a new scheme was derived, with correct hydrogen content, complemented by oxygen (all elements differing from hydrogen are replaced by oxygen). Mass attenuation coefficients and mass stopping powers for this scheme were calculated and compared to the original scheme. Twenty-five CyberKnife treatment plans were recalculated by an in-house developed Monte Carlo system using tissue density and hydrogen content derived from the CT images. The results were compared to Monte Carlo simulations using the original stoichiometric calibration. Between 300 keV and 3 MeV, the relative difference of mass attenuation coefficients is under 1% within all subsets. Between 10 keV and 20 MeV, the relative difference of mass stopping powers goes up to 5% in hard bone and remains below 2% for all other tissue subsets. Dose-volume histograms (DVHs) of the treatment plans present no visual difference between the two schemes. Relative differences of dose indexes D98, D95, D50, D05, D02, and Dmean were analyzed and a distribution centered around zero and of standard deviation below 2% (3 σ) was established. On the other hand, once the hydrogen content is slightly modified, important dose differences are obtained. Monte Carlo dose planning in the field of megavoltage photon radiotherapy is fully achievable using

  6. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    SciTech Connect

    Cho, Herman

    2016-02-28

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  7. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    NASA Astrophysics Data System (ADS)

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3 / 2 , 5 / 2 , 7 / 2, and 9 / 2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  8. Assessment of adult body composition using bioelectrical impedance: comparison of researcher calculated to machine outputted values

    PubMed Central

    Franco-Villoria, Maria; Wright, Charlotte M; McColl, John H; Sherriff, Andrea; Pearce, Mark S

    2016-01-01

    Objectives To explore the usefulness of Bioelectrical Impedance Analysis (BIA) for general use by identifying best-evidenced formulae to calculate lean and fat mass, comparing these to historical gold standard data and comparing these results with machine-generated output. In addition, we explored how to best to adjust lean and fat estimates for height and how these overlapped with body mass index (BMI). Design Cross-sectional observational study within population representative cohort study. Setting Urban community, North East England Participants Sample of 506 mothers of children aged 7–8 years, mean age 36.3 years. Methods Participants were measured at a home visit using a portable height measure and leg-to-leg BIA machine (Tanita TBF-300MA). Measures Height, weight, bioelectrical impedance (BIA). Outcome measures Lean and fat mass calculated using best-evidenced published formulae as well as machine-calculated lean and fat mass data. Results Estimates of lean mass were similar to historical results using gold standard methods. When compared with the machine-generated values, there were wide limits of agreement for fat mass and a large relative bias for lean that varied with size. Lean and fat residuals adjusted for height differed little from indices of lean (or fat)/height2. Of 112 women with BMI >30 kg/m2, 100 (91%) also had high fat, but of the 16 with low BMI (<19 kg/m2) only 5 (31%) also had low fat. Conclusions Lean and fat mass calculated from BIA using published formulae produces plausible values and demonstrate good concordance between high BMI and high fat, but these differ substantially from the machine-generated values. Bioelectrical impedance can supply a robust and useful field measure of body composition, so long as the machine-generated output is not used. PMID:26743700

  9. On the production of cosmogenic nuclides by low-energy neutrons

    NASA Astrophysics Data System (ADS)

    Fanenbruck, O.; Lange, H.-J.; Michel, R.

    1994-07-01

    Monte Carlo codes describing the propagation and interaction of medium-energy particles in matter, in combination with experimental and theoretical cross sections of the underlying nuclear reactions, were successfully applied in model calculations of cosmogenic nuclide production rates. We extended these calculations to reactions of low-energy neutrons in order to allow a consistent interpretation of the entire regime of nuclear reactions involved in galactic cosmic ray (GCR) interactions. Low-energy neutron spectra were calculated for stony meteoroids and lunar surface materials by Monte Carlo techniques using the MORSE code, Emmett (1975), within the HERMES code system. Depth- and size-dependent production rates for the production of Cl-36, Ca-41, Co-60, Ni-59, Kr-80, and Kr-82 by neutron capture were derived by folding these spectra with group cross sections calculated from microscopic neutron-capture data of the evaluated neutron data file ENDF/B VI by the code NJOY. The calculations were validated by modeling the Co-60 production in an artificial stony meteoroid irradiated isotropically by 1.6 GeV protons. The new theoretical production rates were compared with earlier calculations of low-energy neutron capture by Eberhardt et al. and by Spergel et al. (n,gamma)-produced cosmogenic nuclides are sensitive indicators of meteoroid sizes. The extension of the model calculations to longlived and stable (n,gamma) products frees this method from the uncertainties caused by the short-term GCR variations that significantly affect Co-60 production rates. The new production rates are applied to the interpretation of the existing experimental data of (n,gamma) products in lunar drill cores and in meteorites.

  10. Reactive flow measurements and calculations for ZRH sub 2 -based composite explosives

    SciTech Connect

    Murphy, M.J.; Simpson, R.L.; Breithaupt, R.D.; Tarver, C.M.

    1989-08-18

    Cylinder test, Fabry-Perot laser interferometric and detonation velocity-charge diameter experiments were done to determine the detonation reaction zone structures and reaction product equations of state of a family of HMX/AP/ZrH{sub 2}/estane explosives. This experimental data base is used to develop ignition and growth reactive flow models of the detonations waves in these composite explosives. The experiments and calculations clearly demonstrate the Zeldovich-von Neumann-Doering (ZND) structure of the detonation reaction zones which are several millimeters long. The inferred reaction rates imply that the HMX in these formulations reacts first at rates comparable to those measured in other HMX-based explosives and propellants. The remaining components of these explosives then decompose at much slower rates. However, this decomposition is rapid enough to contribute to the propagation of the detonation wave and to the total energy delivered in metal acceleration applications. 22 refs., 9 figs.

  11. Interpretation of an index of phytoplankton population composition calculated from Remote Airborne Fluorsensor (RAF) data

    NASA Technical Reports Server (NTRS)

    Farmer, F. H.

    1981-01-01

    The calculation of indices of phytoplankton population composition from chlorophyll a fluorescence at 685 nm excited by narrow band light at 454 and 539 nm is discussed. The ratio of the fluorescence excited by light of these two wavelengths is a function of the distribution of the phytoplankton between two color groups, designated the golden-brown and the green. The golden-brown group consists of those species which have the highly photosynthetically active carotenoid-chlorophyll-a-protein complexes, i.e. members of the classes Bacillariophyceae, diatoms Dinophyceae, dinoflagellates, and some members of the class Prymnesiophyceae. The green color group consists those species of phytoplankton which apparently lack those complexes, i.e. members of the classes Chlorophyceae, Euglenophyceae, Prasinophyceae, Eustigmatophyceae, Xanthophyceae, and a few members of the Prymnesiophyceae. A few species of phytoplankton appear to have intermediate characteristics, and would apparently belong to neither group. Most of these species are members of the class Cryptophyceae. The composition index for this class is examined in detail.

  12. Proximate biochemical composition and caloric content calculated from elemental CHN analysis: a stoichiometric concept.

    PubMed

    Gnaiger, E; Bitterlich, G

    1984-06-01

    Carbohydrate, lipid, and protein compositions are stoichiometrically related to organic CHN (carbon, hydrogen, nitrogen) contents. Elemental CHN analyses of total biomass and ash, therefore, provide a basis for the calculation of proximate biochemical composition and bomb caloric value. The classical nitrogen to protein conversion factor (6.25) should be replaced by 5.8±0.13. A linear relation exists between the mass fraction of non-protein carbon and the carbohydrate and lipid content. Residual water in dry organic matter can be estimated with the additional information derived from hydrogen measurements.The stoichiometric CHN method and direct biochemical analysis agreed within 10% of ash-free dry biomass (for muscle, liver and fat tissue of silver carp; gut contents composed of detritus and algae; commercial fish food). The detrital material, however, had to be corrected for non-protein nitrogen.A linear relationship between bomb caloric value and organic carbon fractions was derived on the basis of thermodynamic and stoichiometric principles, in agreement with experimental data published for bacteria, algae, protozoa and invertebrates. The highly automatic stoichiometric CHN method for the separation of nutrient contents in biomass extends existing ecophysiological concepts for the construction of balanced carbon and nitrogen, as well as biochemical and energy budgets.

  13. Cross Sections for the Production of Cosmogenic Nuclides with Protons up to 400 MeV for the Interpretation of Cosmic-Ray-produced Nuclides

    NASA Astrophysics Data System (ADS)

    Schiekel, Th.; Rosel, R.; Herpers, U.; Bodemann, R.; Leya, I.; Gloris, M.; Michel, R.; Dittrich, B.; Kubik, P.; Suter, M.

    1993-07-01

    Integral excitation functions of the cosmogenic nuclides are the basic requirement for the interpretation of interactions between cosmic ray particles and extraterrestrial and terrestrial matter. Together with the knowledge of primary and secondary particle fields inside an irradiated body, model calculations can be developed to interpret abundances of cosmogenic nuclides in dependencies of the irradiation history of the irradiated body and of the cosmic particle ray itself. The quality of those model calculations depends on the quality of the available cross-section database, which is neither comprehensive nor reliable for the most important nuclides like the long-lived radionuclides (i.e., 10Be, 26Al, 36Cl, 41Ca) and the stable rare gas isotopes. For a systematic investigation in this field of science we carried out several irradiation experiments with protons in the energy region between 45 MeV and 400 MeV at the Paul Scherrer Institut (Villigen, Switzerland) and the Laboratoire Nationale Saturne (Saclay, France) using the stacked foil technique. We included 21 different target elements with Z between 6 and 79 (C, N as Si3N4, O as SiO2, Mg, Al, Si, Ca as CaC2H2O4, Ti, V, Mn as Mn/Ni alloy, Fe, Co, Ni, Cu, Sr as SrF2, Y, Zr, Nb, Rh, Ba as Ba containing glass and Au) in our experiments. The proton fluxes were monitored via the reaction 27Al(p,3p3n)22Na using the evaluated data of [1]. Residual nuclides were measured by X-, gamma-, and after a chemical separation by accelerator mass spectrometry. In order to check the quality of our experimental procedures we included some target elements in our new experiments for which consistent excitation functions have already been determined [2,3,4]. Our new data show excellent agreement with the earlier measurements. We measured cross sections for more than 120 different reactions. Here we report on the results for target elements with Z up to 28. The exsisting database of experimental excitation functions for the production

  14. A comparison of measured and calculated thermal stresses in a hybrid metal matrix composite spar cap element

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.; Taylor, A. H.; Sakata, I. F.

    1985-01-01

    A hybrid spar of titanium with an integrally brazed composite, consisting of an aluminum matrix reinforced with boron-carbide-coated fibers, was heated in an oven and the resulting thermal stresses were measured. Uniform heating of the spar in an oven resulted in thermal stresses arising from the effects of dissimilar materials and anisotropy of the metal matrix composite. Thermal stresses were calculated from a finite element structural model using anisotropic material properties deduced from constituent properties and rules of mixtures. Comparisons of calculated thermal stresses with measured thermal stresses on the spar are presented. It was shown that failure to account for anisotropy in the metal matrix composite elements would result in large errors in correlating measured and calculated thermal stresses. It was concluded that very strong material characterization efforts are required to predict accurate thermal stresses in anisotropic composite structures.

  15. Calculation of contraction rates due to shrinkage in light-cured composites.

    PubMed

    Alvarez-Gayosso, Carlos; Barceló-Santana, Federico; Guerrero-Ibarra, Jorge; Sáez-Espínola, Gabriel; Canseco-Martínez, Miguel A

    2004-03-01

    To calculate the contraction rate that results from polymerization shrinkage in photo-cured resins. Fourteen materials were irradiated in a previously developed instrument. This instrument uses measurements of deflection using a 'bonded disk' method. Six measurements were made on each material at 20 +/- 2 degrees C and 70 +/- 10% RH. Means and standard deviations were analyzed. Shrinkage-strain and contraction rate are reported. Total shrinkage-strain for photo-polymerized resins (packable and flowable composites) varies between 1.65 and 4.16%. Both are ormocers. The contraction rate for photo-polymerized resins varies between 55.71 and 167.00 microm/min. Packable resins present a lower contraction rate than flowable resins. The distance-time graph is linear. The slope of this line is the average velocity. This concept was used to calculate the average contraction rate. The monomer percentage affects the contraction rate, because higher contraction rate means higher percentage of monomer. We can infer that contraction rate bears some relation to polymerization shrinkage.

  16. Two interfacial shear strength calculations based on the single fiber composite test

    NASA Astrophysics Data System (ADS)

    Zhandarov, S. F.; Pisanova, E. V.

    1996-07-01

    The fragmentation of a single fiber embedded in a polymer matrix upon stretching (SFC test) provides valuable information on the fiber-matrix bond strength (τ), which determines stress transfer through the interface and, thus, significantly affects the mechanical properties of the composite material. However, the calculated bond strength appears to depend on data interpretation, i.e., on the applied theoretical model, since the direct result of the SFC test is the fiber fragment length distribution rather than the τ value. Two approaches are used in SFC testing for calculation of the bond strength: 1) the Kelly-Tyson model, in which the matrix is assumed to be totally elastic and 2) the Cox model using the elastic constants of the fiber and the matrix. In this paper, an attempt has been made to compare these two approaches employing theory as well as the experimental data of several authors. The dependence of the tensile stress in the fiber and the interfacial shear stress on various factors has been analyzed. For both models, the mean interfacial shear stress in the fragment of critical length (lc) was shown to satisfy the same formula (τ) = (σcD)/2lc, where D is the fiber diameter and σc is the tensile strength of a fiber at gauge length equal to lc. However, the critical lengths from the Kelly-Tyson approach and Cox model are differently related to the fragment length distribution parameters such as the mean fragment length. This discrepancy results in different (τ) values for the same experimental data set. While the main parameter in the Kelly-Tyson model assumed constant for a given fiber-matrix pair is the interfacial shear strength, the ultimate (local) bond strength τult may be seen as the corresponding parameter in the Cox model. Various τult values were obtained for carbon fiber-epoxy matrix systems by analyzing the data of continuously monitored single fiber composite tests. Whereas the mean value of the interfacial shear stress calculated in

  17. Radio-nuclide mixture identification using medium energy resolution detectors

    DOEpatents

    Nelson, Karl Einar

    2013-09-17

    According to one embodiment, a method for identifying radio-nuclides includes receiving spectral data, extracting a feature set from the spectral data comparable to a plurality of templates in a template library, and using a branch and bound method to determine a probable template match based on the feature set and templates in the template library. In another embodiment, a device for identifying unknown radio-nuclides includes a processor, a multi-channel analyzer, and a memory operatively coupled to the processor, the memory having computer readable code stored thereon. The computer readable code is configured, when executed by the processor, to receive spectral data, to extract a feature set from the spectral data comparable to a plurality of templates in a template library, and to use a branch and bound method to determine a probable template match based on the feature set and templates in the template library.

  18. Production rates of terrestrial in-situ-produced cosmogenic nuclides

    SciTech Connect

    Reedy, R.C.; Tuniz, C.; Fink, D.

    1993-12-31

    Production rates of cosmogenic nuclides made in situ in terrestrial samples and how they are applied to the interpretation of measured radionuclide concentrations were discussed at a one-day Workshop held 2 October 1993 in Sydney, Australia. The status of terrestrial in-situ studies using the long-lived radionuclides {sup 10}Be, {sup 14}C, {sup 26}Al, {sup 36}Cl, and {sup 41}Ca and of various modeling and related studies were presented. The relative uncertainties in the various factors that go into the interpretation of these terrestrial in-situ cosmogenic nuclides were discussed. The magnitudes of the errors for these factors were estimated and none dominated the final uncertainty.

  19. Measurements of cosmogenic nuclides in lunar rock 64455

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Kohl, C. P.; Nishiizumi, K.; Caffee, M. W.; Finkel, R. C.; Southon, J. R.

    1993-01-01

    Eleven samples were ground from the glass coated surface of lunar rock 64455,82 with an average depth resolution of 50 microns and were measured for Be-10, Al-26, and Cl-36 using AMS (accelerator mass spectrometry). Results show no evidence of SCR (solar cosmic ray) effects. The flat cosmogenic nuclide profiles and activity levels are consistent with a 2 My exposure history for the rock and a sample location on the bottom of the rock. These AMS measurements are some of the most precise ever obtained for these three nuclides. This precision and the demonstrated fine depth resolution will enable us to conduct a number of detailed studies of depth effects in lunar and meteoritic samples, including investigating SCR effects in the surface exposed top of the glass coating of 64455 and possibly in the underlying rock.

  20. Measurements of cosmogenic nuclides in lunar rock 64455

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Kohl, C. P.; Nishiizumi, K.; Caffee, M. W.; Finkel, R. C.; Southon, J. R.

    1993-01-01

    Eleven samples were ground from the glass coated surface of lunar rock 64455,82 with an average depth resolution of 50 microns and were measured for Be-10, Al-26, and Cl-36 using AMS (accelerator mass spectrometry). Results show no evidence of SCR (solar cosmic ray) effects. The flat cosmogenic nuclide profiles and activity levels are consistent with a 2 My exposure history for the rock and a sample location on the bottom of the rock. These AMS measurements are some of the most precise ever obtained for these three nuclides. This precision and the demonstrated fine depth resolution will enable us to conduct a number of detailed studies of depth effects in lunar and meteoritic samples, including investigating SCR effects in the surface exposed top of the glass coating of 64455 and possibly in the underlying rock.

  1. Hot demonstration of proposed commercial nuclide removal technology

    SciTech Connect

    Lee, D.

    1996-10-01

    This task covers the development and operation of an experimental test unit located in a Building 4501 hot cell within Building 4501 at Oak Ridge National Laboratory (ORNL). This equipment is designed to test radionuclides removal technologies under continuous operatoin on actual ORNL Melton Valley Storage Tank (MVST) supernatant, Savannah River high-level waste supernatant, and Hanford supernatant. The latter two may be simulated by adding the appropriate chemicals and/or nuclides to the MVST supernatant.

  2. Automatic Software Processing for Inventories of Nuclides (ASPIN)

    SciTech Connect

    Luca Gratton; J.M. Rammsy

    2001-10-22

    EQ6 users have difficulties tracking isotopic concentrations in a system with chemical and nuclear decay reactions. The capability to track isotopic concentrations is particularly important for simulating the degradation of the spent nuclear fuels. Isotopic tracking is necessary to evaluate the criticality risk associated with fissile material relocation inside of a disposal container. A code called ASPRIN (Automatic Software PRocessing, Inventories of Nuclides) was created to allow isotopic tracking using the results of EQ6 simulations.

  3. Nuclide radioactive decay data uncertainties library

    NASA Astrophysics Data System (ADS)

    Barabanova, D. S.; Zherdev, G. M.

    2017-01-01

    The results of the developing the library of uncertainties of radioactive decay data in the ABBN data library format are described. Different evaluations of uncertainties were compared and their effects on the results of calculations of residual energy release were determined using the test problems and experiment. Tables were generated in the ABBN format with the data obtained on the basis of libraries in ENDF-6 format. 3821 isotopes from the ENDF/B-7 data library, 3852 isotopes from the JEFF-3.11 data library and 1264 isotopes from the JENDL-4.0 data library were processed. It was revealed that the differences in the evaluations accepted in different decay data libraries are not so big, although they sometimes exceed the uncertainties assigned to the data in the ENDF/B-7 and JEFF-3.11 libraries, which as a rule, they agree with each other. On the basis of developed method it is supposed to create a library of data uncertainties for radioactive decay within the constant data system in FSUE RFNC-VNIIEF with its further connection with CRYSTAL module.

  4. Effect of elemental compositions on Monte Carlo dose calculations in proton therapy of eye tumors

    NASA Astrophysics Data System (ADS)

    Rasouli, Fatemeh S.; Farhad Masoudi, S.; Keshazare, Shiva; Jette, David

    2015-12-01

    Recent studies in eye plaque brachytherapy have found considerable differences between the dosimetric results by using a water phantom, and a complete human eye model. Since the eye continues to be simulated as water-equivalent tissue in the proton therapy literature, a similar study for investigating such a difference in treating eye tumors by protons is indispensable. The present study inquires into this effect in proton therapy utilizing Monte Carlo simulations. A three-dimensional eye model with elemental compositions is simulated and used to examine the dose deposition to the phantom. The beam is planned to pass through a designed beam line to moderate the protons to the desired energies for ocular treatments. The results are compared with similar irradiation to a water phantom, as well as to a material with uniform density throughout the whole volume. Spread-out Bragg peaks (SOBPs) are created by adding pristine peaks to cover a typical tumor volume. Moreover, the corresponding beam parameters recommended by the ICRU are calculated, and the isodose curves are computed. The results show that the maximum dose deposited in ocular media is approximately 5-7% more than in the water phantom, and about 1-1.5% less than in the homogenized material of density 1.05 g cm-3. Furthermore, there is about a 0.2 mm shift in the Bragg peak due to the tissue composition difference between the models. It is found that using the weighted dose profiles optimized in a water phantom for the realistic eye model leads to a small disturbance of the SOBP plateau dose. In spite of the plaque brachytherapy results for treatment of eye tumors, it is found that the differences between the simplified models presented in this work, especially the phantom containing the homogenized material, are not clinically significant in proton therapy. Taking into account the intrinsic uncertainty of the patient dose calculation for protons, and practical problems corresponding to applying patient

  5. Constraints in calculations of evaporative losses in arid climates using the stable isotope composition of water

    NASA Astrophysics Data System (ADS)

    Skrzypek, G.; Mydlowski, A.; Dogramaci, S.; Hedley, P.; Gibson, J. J.; Grierson, P. F.

    2014-12-01

    Accurate quantification of evaporative losses to the atmosphere from surface water bodies is essential for calibration and validation of hydrological models, particularly in remote arid and semi-arid regions, where rivers and lakes are generally minimally gauged. In this study, we reviewed and combined the most recent equations for estimation of evaporative losses based on the revised Craig-Gordon model. We designed new software, called Hydrocalculator, which allows quick and robust estimation of evaporative losses based on the isotopic composition of water. We validated Hydrocalculator by testing the range of uncertainty in the estimation of evaporative losses in arid climates by cross-validating a simplified stable isotope model with field pan evaporation experiments. The use of standardized pans (1.2 m diameter, volume 300 dm3) in hot and dry climates (temperature 29°C and relative humidity between 19 and 26%) allowed simulation of fast evaporation from shallow water bodies. Several factors may contribute to the uncertainty in the evaporative loss calculations. The analytical uncertainty in the determination of the stable isotope composition of water may contribute to ~0.6% for δ18O and ~1.4% for δ2H. The model is less sensitive to uncertainty in climatic variables and an uncertainty of 1°C in air temperature will result only in the ~0.1% uncertainty in δ18O and δ2H. However, uncertainty in relative humidity of 10% will result in an uncertainty in the final outcome of 0.4% (δ18O) and 1.0% (δ2H). Significantly higher uncertainty in evaporative loss estimation is thus associated with uncertainty in ambient air moisture estimation or analysis. An error of 20‰ in δ2H and 5.0‰ in δ18O will result in a maximum difference of 2.4% (δ2H) and 1.7% (δ18O) in the final calculations. Hydrocalculator can thus provide accurate, rapid and cost-effective insight into the water balance of surface water pools. We used the new software to determine the origin of

  6. Recent developments in cosmogenic nuclide production rate scaling

    NASA Astrophysics Data System (ADS)

    Lifton, N. A.

    2013-12-01

    A new cosmogenic nuclide production rate scaling model based on analytical fits to Monte Carlo simulations of atmospheric cosmic ray flux spectra (both of which agree well with measured spectra) enables identification and quantification of the biases in previously published models (Lifton, N., Sato, T., Dunai, T., in review, Earth and Planet. Sci. Lett.). Scaling predictions derived from the new model (termed LSD) suggest two potential sources of bias in the previous models: different energy responses of the secondary neutron detectors used in developing the models, and different geomagnetic parameterizations. In addition, the particle flux spectra generated by the LSD model allow one to generate nuclide-specific scaling factors that reflect the influences of the flux energy distribution and the relevant excitation functions (probability of nuclide production in a given nuclear reaction as a function of energy). Resulting scaling factors indicate 3He shows the strongest positive deviation from the flux-based scaling, while 14C exhibits a negative deviation. These results are consistent with previous studies showing an increasing 3He/10Be ratio with altitude in the Himalayas, but with a much lower magnitude for the effect. Furthermore, the new model provides a flexible framework for exploring the implications of future advances in model inputs. For example, the effects of recently updated paleomagnetic models (e.g. Korte et al., 2011, Earth and Planet Sci. Lett. 312, 497-505) on scaling predictions will also be presented.

  7. The determination of critical nuclides in PWR waste streams

    SciTech Connect

    De Goeyse, A.

    1993-12-31

    The safety studies concerning the final disposal of low- and intermediate-level radioactive waste take into consideration a series of long-lived radionuclides. The problem the producers have to cope with comes from the fact that those nuclides, which are mainly (pure) {beta} emitters or {alpha} emitters, cannot be measured by a direct current method such as gamma scanning. Their determination involves sophisticated radiochemical techniques which are difficult to implement by a producer on a routine basis for normal production waste. A current method for the determination of those nuclides in the waste streams produced by a nuclear power reactor consists in applying correlation factors or scaling factors between those critical nuclides and so called key radionuclides, which can be easily measured and are representative for the occurrence of activation products and fission products in the waste streams. In order to identify and define those correlation factors, ONDRAF/NIRAS, has subcontracted, in agreement with the waste producer (ELECTRABEL), a complete study to the engineering company BELGATOM (BA) for the different waste streams produced by the seven Belgian PWR plants.

  8. Identification of Heavy and Superheavy Nuclides Using Chemical Separator Systems

    SciTech Connect

    Turler, Andreas

    1999-12-31

    With the recent synthesis of superheavy nuclides produced in the reactions {sup 48}Ca+{sup 238}U and {sup 48}Ca+{sup 242,244}Pu, much longer-lived nuclei than the previously known neutron-deficient isotopes of the heaviest elements have been identified. Half-lives of several hours and up to several years have been predicted for the longest-lived isotopes of these elements. Thus, the sensitivity of radiochemical separation techniques may present a viable alternative to physical separator systems for the discovery of some of the predicted longer-lived heavy and superheavy nuclides. The advantages of chemical separator systems in comparison to kinematic separators lie in the possibility of using thick targets, high beam intensities spread over larger target areas and in providing access to nuclides emitted under large angles and low velocities. Thus, chemical separator systems are ideally suited to study also transfer and (HI, axn) reaction products. In the following, a study of (HI, axn) reactions will be presented and prospects to chemically identify heavy and superheavy elements discussed.

  9. Cosmogenic nuclide age constraints on Middle Stone Age lithics from Niassa, Mozambique

    NASA Astrophysics Data System (ADS)

    Mercader, Julio; Gosse, John C.; Bennett, Tim; Hidy, Alan J.; Rood, Dylan H.

    2012-07-01

    The late phases of the Middle Stone Age (MSA) in the East African Rift System (EARS) are known for their evolutionary shifts and association with bottlenecks, transcontinental expansion, and climatic fluctuations. The chronology of MSA sites contemporaneous with these eco-demographic upheavals is uncertain because of the scarcity of datable sites and the poor understanding of their depositional and erosional histories. We apply terrestrial cosmogenic nuclide dating in a stratigraphic section with a complex exposure history to the study of the Luchamange Beds, a widespread sedimentological unit underlying MSA sites from the shores of Lake Niassa (Mozambican EARS). We use an innovative approach, which may be applicable elsewhere, to calculate their age using a Monte Carlo-based Bayesian model that links depth profiles of 26Al and 10Be, and uses other geomorphic and cosmogenic nuclide age constraints on episodic erosion and burial. The age of the basal Luchamange Beds is 42 + 77/-15 ka, and the MSA occupation on top is 29 + 3/-11 ka. These dates suggest temporal overlap between MSA and the earliest Later Stone Age and diversity in cultural manifestations at the end of the MSA.

  10. Rotational structure of the odd-proton nuclide 171Tm: A projected shell model study

    NASA Astrophysics Data System (ADS)

    Liu, YanXin; Chen, FangQi; Yu, ShaoYing; Sun, Yang

    2015-05-01

    Deformed odd-mass nuclei are ideal examples where the interplay between single-particle and collective degrees of freedom can be studied. Inspired by the recent experimental high-spin data in the odd-proton nuclide 171Tm, we perform projected shell model (PSM) calculations to investigate structure of the ground band and other bands based on isomeric states. In addition to the usual quadrupole-quadrupole force in the Hamiltonian, we employ the hexadecapole-hexadecapole ( HH) interaction, in a self-consistent way with the hexadecapole deformation of the deformed basis. It is found that the known experimental data can be well described by the PSM calculation. The effect of the HH force on the quasiparticle isomeric states is discussed.

  11. Cosmic-ray-produced stable nuclides: various production rates and their implications

    SciTech Connect

    Reedy, R.C.

    1981-06-15

    The rates for a number of reactions producing certain stable nuclides, such as /sup 3/He and /sup 4/He, and fission in the moon are calculated for galactic-cosmic-ray particles and for solar protons. Solar-proton-induced reactions with bromine usually are not an important source of cosmogenic Kr isotopes. The /sup 130/Ba(n,p) reaction cannot account for the undercalculation of /sup 130/Xe production rates. Calculated production rates of /sup 15/N, /sup 13/C, and /sup 2/H agree fairly well with rates inferred from measured excesses of these isotopes in samples with long exposure ages. Cosmic-ray-induced fission of U and Th can produce significant amounts of fission tracks and of /sup 86/Kr, /sup 134/Xe, and /sup 136/Xe, especially in samples with long exposures to cosmic-ray particles.

  12. Re-calculating the pH record from boron isotopic composition of biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Paris, G.; Gaillardet, J.; Louvat, P.

    2010-12-01

    The boron isotopic composition of marine carbonates (δ11Bcarb, ‰) has been proposed as a seawater paleo-acidity proxy (Hemming and Hanson, 1992; Vengosh et al., 1991). This proxy has been extensively used to reconstruct seawater paleo-pH and eventually atmospheric pCO2 during recent times or over short time-scales. However, it requires the knowledge of seawater δ11B value. Boron has a residence time of 10-20 My in seawater, longer than the mixing time of the ocean. The boron isotopic composition of seawater (δ11Bsw) is thus homogeneous in the modern ocean, yet it is not known in the past even though reconstruction and modeling have been attempted that rely on many hypotheses (Lemarchand et al., 2002; Pearson and Palmer, 2000). The boron isotopic composition of Cenozoic evaporites has been recently reconstructed using the direct record of Cenozoic evaporites (Paris et al., 2010). This reconstruction suggests that δ11Bsw has significantly changed along the last 40 Ma, in agreement with other parameters of the oceanic chemical composition. The δ11Bsw change amplitude appears to be stronger than suggested by models. In this presentation, we explore the consequences of this reconstruction on paleo-pH calculation for the late Cenozoic from published boron isotope record in biogenic carbonates (Pearson and Palmer, 2000; Pearson et al., 2009; Seki et al., 2010; Spivack et al., 1993). It points out the inconsistency between different dataset, due to the techniques used for boron isotopic measurement. In conclusion, we suggest that the seawater pH variations are not known with a sufficient precision over the last 35 My and that seawater surface pH could have likely remained constant. Hemming, N.G., and Hanson, G.N. (1992), Boron isotopic composition and concentration in modern marine carbonates: Geochimica et Cosmochimica Acta, v. 56, p. 537-543. Lemarchand, D., et al. (2002), Boron isotope systematics in large rivers: implications for the marine boron budget and

  13. Cosmogenic neutron-capture-produced nuclides in stony meteorites

    NASA Technical Reports Server (NTRS)

    Spergel, M. S.; Reedy, R. C.; Lazareth, O. W.; Levy, P. W.; Slatest, L. A.

    1986-01-01

    The complete neutron-flux results and production rates for Cl-36, Ni-59, and Co-60 in stony meteorites of various radii and composition are presented. The relative neutron source strengths and neutron production-versus-depth profiles were determined by using calculated H-3 production rates. The absolute source strengths were normalized to that determined for the moon by Woolum et al. (1975). The energy spectrum of the source neutrons and the neutron transport calculations, which employed the ANISN computer code, were similar to those used for the moon by Lingenfelter et al. (1972). The production rates of the three radionuclides were determined as a function of depth in various spherical meteoroids from the calculated equilibrium neutron-flux distributions and from energy-dependent neutron-capture cross sections. Rates for producing these radionuclides by spallation reactions were also calculated.

  14. Method of calculating the phase composition of SiC-Si-C materials obtained by silicon infiltration of carbon matrices

    NASA Astrophysics Data System (ADS)

    Ershov, A. E.; Shikunov, S. L.; Kurlov, V. N.

    2017-06-01

    The synthesis of SiC-Si-C materials by siliconizing porous carbon matrices has been considered, and a method of determining their phase composition has been devised. Preforms of two types have been siliconized, i.e., biomorphic carbon matrices prepared by wood pyrolysis and artificial porous graphites prepared by mixing and compacting carbon powders with an organic binder. The calculated phase compositions are in good agreement with microstructure metallographic examination data.

  15. Production rates of cosmogenic nuclides in stony meteorites

    SciTech Connect

    Divadeenam, M.; Gabriel, T.A.; Lazareth, O.W.; Spergel, M.S.; Ward, T.E.

    1989-01-01

    Monte Carlo calculations of /sup 26/Al and /sup 53/Mn production due to spallation induced by cosmogenic protons in model meteorite composition similar to L Chondrite has yielded predictions which are consistent with the observed decay rates in L Chondrite stony meteorites. The calculated /sup 26/Al production rate (54 dpm/kg) in a 1 m diameter meteorite is within 1/2 S.D. of the mean (49 +- 11 dpm/kg) taken from 100 bulk determinations in L Chondrite samples compiled in Nishiizumi (1987). Similarly calculated average value for /sup 53/Mn (223 dpm/kg) is consistent with one S.D. off the mean in the widely scattered /sup 53/Mn data (362 +- 113 dpm/kg) compiled by Nishiizumi (1987). 9 refs.

  16. Phase composition of Al-Ti-Nb-Mo γ alloys in the heat-treatment temperature range: Calculation and experiment

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Dashkevich, N. I.; Bel'tyukova, S. O.

    2015-07-01

    The phase composition of TNM-type Al-Ti-Nb-Mo γ alloys at heat-treatment temperatures is quantitatively studied using the Thermo-Calc program package and experimental methods. Isothermal cross sections are calculated and the joint influence of two alloying elements on the phase composition of the alloy is determined at the mean concentration of a third component. Based on the calculations of vertical cross sections, the boundaries of the four-phase eutectoid reaction α → α2 + β + γ are found. The temperature is shown to significantly influence the phase compositions of the γ alloys, among them the mass fractions of various phases (α, β, γ,α2) and the element concentration in them.

  17. Notre Dame Nuclear Database: A New Chart of Nuclides

    NASA Astrophysics Data System (ADS)

    Lee, Kevin; Khouw, Timothy; Fasano, Patrick; Mumpower, Matthew; Aprahamian, Ani

    2014-09-01

    Nuclear data is critical to research fields from medicine to astrophysics. We are creating a database, the Notre Dame Nuclear Database, which can store theoretical and experimental datasets. We place emphasis on storing metadata and user interaction with the database. Users are able to search in addition to the specific nuclear datum, the author(s), the facility where the measurements were made, the institution of the facility, and device or method/technique used. We also allow users to interact with the database by providing online search, an interactive nuclide chart, and a command line interface. The nuclide chart is a more descriptive version of the periodic table that can be used to visualize nuclear properties such as half-lives and mass. We achieve this by using D3 (Data Driven Documents), HTML, and CSS3 to plot the nuclides and color them accordingly. Search capabilities can be applied dynamically to the chart by using Python to communicate with MySQL, allowing for customization. Users can save the customized chart they create to any image format. These features provide a unique approach for researchers to interface with nuclear data. We report on the current progress of this project and will present a working demo that highlights each aspect of the aforementioned features. This is the first time that all available technologies are put to use to make nuclear data more accessible than ever before in a manner that is much easier and fully detailed. This is a first and we will make it available as open source ware.

  18. Calculation of the relative uniformity coefficient on the green composites reinforced with cotton and hemp fabric

    NASA Astrophysics Data System (ADS)

    Baciu, Florin; Hadǎr, Anton; Sava, Mihaela; Marinel, Stǎnescu Marius; Bolcu, Dumitru

    2016-06-01

    In this paper it is studied the influence of discontinuities on elastic and mechanical properties of green composite materials (reinforced with fabric of cotton or hemp). In addition, it is studied the way variations of the volume f the reinforcement influences the elasticity modulus and the tensile strength for the studied composite materials. In order to appreciate the difference in properties between different areas of the composite material, and also the dimensions of the defective areas, we have introduced a relative uniformity coefficient with which the mechanical behavior of the studied composite is compared with a reference composite. To validate the theoretical results we have obtained we made some experiments, using green composites reinforced with fabric, with different imperfection introduced special by cutting the fabric.

  19. Impact of dietary fiber energy on the calculation of food total energy value in the Brazilian Food Composition Database.

    PubMed

    Menezes, Elizabete Wenzel de; Grande, Fernanda; Giuntini, Eliana Bistriche; Lopes, Tássia do Vale Cardoso; Dan, Milana Cara Tanasov; Prado, Samira Bernardino Ramos do; Franco, Bernadette Dora Gombossy de Melo; Charrondière, U Ruth; Lajolo, Franco Maria

    2016-02-15

    Dietary fiber (DF) contributes to the energy value of foods and including it in the calculation of total food energy has been recommended for food composition databases. The present study aimed to investigate the impact of including energy provided by the DF fermentation in the calculation of food energy. Total energy values of 1753 foods from the Brazilian Food Composition Database were calculated with or without the inclusion of DF energy. The energy values were compared, through the use of percentage difference (D%), in individual foods and in daily menus. Appreciable energy D% (⩾10) was observed in 321 foods, mainly in the group of vegetables, legumes and fruits. However, in the Brazilian typical menus containing foods from all groups, only D%<3 was observed. In mixed diets, the DF energy may cause slight variations in total energy; on the other hand, there is appreciable energy D% for certain foods, when individually considered. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Test of IMME in fp shell via direct mass measurements of nuclides

    NASA Astrophysics Data System (ADS)

    Zhang, Y. H.; Xu, H. S.; Litvinov, Yu A.; Tu, X. L.; Yan, X. L.; Typel, S.; Blaum, K.; Wang, M.; Zhou, X. H.; Sun, Y.; Brown, B. A.; Yuan, Y. J.; Xia, J. W.; Yang, J. C.; Audi, G.; Chen, X. C.; Jia, G. B.; Hu, Z. G.; Ma, X. W.; Mao, R. S.; Mei, B.; Shuai, P.; Sun, Z. Y.; Wang, S. T.; Xiao, G. Q.; Xu, X.; Yamaguchi, T.; Yamaguchi, Y.; Zang, Y. D.; Zhao, H. W.; Zhao, T. C.; Zhang, W.; Zhan, W. L.

    2013-03-01

    Isochronous mass spectrometry has been applied to neutron-deficient 58Ni projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of four shortlived Tz = -3/2 nuclides 41Ti, 45Cr, 49Fe, and 53Ni have been measured with a precision of 20 — 40 keV. The new mass data enabled for the first time to test the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observed that the IMME is inconsistent with the generally accepted quadratic form for the A = 53, T = 3/2 quartet. We performed full space shell model calculations and compared them with the new experimental results. The main results were published in Y.H. Zhang et al., Physical Review Letters 109 (2012). Here we give details on the experiment and data analysis as well as summarize the main findings.

  1. ANDROS: A code for Assessment of Nuclide Doses and Risks with Option Selection

    SciTech Connect

    Begovich, C.L.; Sjoreen, A.L.; Ohr, S.Y.; Chester, R.O.

    1986-11-01

    ANDROS (Assessment of Nuclide Doses and Risks with Option Selection) is a computer code written to compute doses and health effects from atmospheric releases of radionuclides. ANDROS has been designed as an integral part of the CRRIS (Computerized Radiological Risk Investigation System). ANDROS reads air concentrations and environmental concentrations of radionuclides to produce tables of specified doses and health effects to selected organs via selected pathways (e.g., ingestion or air immersion). The calculation may be done for an individual at a specific location or for the population of the whole assessment grid. The user may request tables of specific effects for every assessment grid location. Along with the radionuclide concentrations, the code requires radionuclide decay data, dose and risk factors, and location-specific data, all of which are available within the CRRIS. This document is a user manual for ANDROS and presents the methodology used in this code.

  2. Speeding up the flash calculations in two-phase compositional flow simulations - The application of sparse grids

    NASA Astrophysics Data System (ADS)

    Wu, Yuanqing; Kowitz, Christoph; Sun, Shuyu; Salama, Amgad

    2015-03-01

    Flash calculations have become a performance bottleneck in the simulation of compositional flow in subsurface reservoirs. We apply a sparse grid surrogate model to substitute the flash calculation and thus try to remove the bottleneck from the reservoir simulation. So instead of doing a flash calculation in each time step of the simulation, we just generate a sparse grid approximation of all possible results of the flash calculation before the reservoir simulation. Then we evaluate the constructed surrogate model to approximate the values of the flash calculation results from this surrogate during the simulations. The execution of the true flash calculation has been shifted from the online phase during the simulation to the offline phase before the simulation. Sparse grids are known to require only few unknowns in order to obtain good approximation qualities. In conjunction with local adaptivity, sparse grids ensure that the accuracy of the surrogate is acceptable while keeping the memory usage small by only storing a minimal amount of values for the surrogate. The accuracy of the sparse grid surrogate during the reservoir simulation is compared to the accuracy of using a surrogate based on regular Cartesian grids and the original flash calculation. The surrogate model improves the speed of the flash calculations and the simulation of the whole reservoir. In an experiment, it is shown that the speed of the online flash calculations is increased by about 2000 times and as a result the speed of the reservoir simulations has been enhanced by 21 times in the best conditions.

  3. Determining the composition of gold nanoparticles: a compilation of shapes, sizes, and calculations using geometric considerations

    NASA Astrophysics Data System (ADS)

    Mori, Taizo; Hegmann, Torsten

    2016-10-01

    Size, shape, overall composition, and surface functionality largely determine the properties and applications of metal nanoparticles. Aside from well-defined metal clusters, their composition is often estimated assuming a quasi-spherical shape of the nanoparticle core. With decreasing diameter of the assumed circumscribed sphere, particularly in the range of only a few nanometers, the estimated nanoparticle composition increasingly deviates from the real composition, leading to significant discrepancies between anticipated and experimentally observed composition, properties, and characteristics. We here assembled a compendium of tables, models, and equations for thiol-protected gold nanoparticles that will allow experimental scientists to more accurately estimate the composition of their gold nanoparticles using TEM image analysis data. The estimates obtained from following the routines described here will then serve as a guide for further analytical characterization of as-synthesized gold nanoparticles by other bulk (thermal, structural, chemical, and compositional) and surface characterization techniques. While the tables, models, and equations are dedicated to gold nanoparticles, the composition of other metal nanoparticle cores with face-centered cubic lattices can easily be estimated simply by substituting the value for the radius of the metal atom of interest.

  4. ICoN, the Interactive Chart of Nuclides

    NASA Astrophysics Data System (ADS)

    Lee, Kevin; Mumpower, Matthew; Aprahamian, Ani

    2015-10-01

    Nuclear data is critical to research fields from medicine to astrophysics. The chart of nuclides is a more descriptive version of the periodic table that can be used to visualize nuclear properties such as half-lives and mass. We have created ICoN (simply short for Interactive Chart of Nuclides), an API which can be used to visualize theoretical and experimental datasets. This visualization is achieved by using D3 (Data Driven Documents), HTML, and CSS3 to plot the elements and color them accordingly. ICoN features many customization options that users can access that are dynamically applied to the chart without reloading the page. Users can save the customized chart they create to various formats. We have constructed these features in order to provide a unique approach for researchers to interface with nuclear data. ICoN can also be used on all electronic devices without loss of support. We report on the current progress of this project and will present a working demo that highlights each aspect of the aforementioned features. This is the first time that all available technologies are put to use to make nuclear data more accessible than ever before. This is a first and we will make it available as open source ware.

  5. Forbush decreases geomagnetic and atmospheric effects cosmogenic nuclides

    NASA Technical Reports Server (NTRS)

    Flueckiger, E. O.

    1986-01-01

    An overview and synthesis is given of recent developments that have occurred in the areas of Forbush decreases, geomagnetic and atmospheric effects, and cosmogenic nuclides. Experimental evidence has been found for substantial differences in the effects of the various types of interplanetary perturbations on cosmic rays, and for a dependence of these effects on the three-dimensional configuration of the interplanetary medium. In order to fully understand and to be able to simulate the solar cosmic ray particle access to the polar regions of the earth we need accurate models of the magnetospheric magnetic field. These models must include all major magnetospheric current systems (in particular the field aligned currents), and they should represent magnetically quiet time periods as well as different levels of geomagnetic activity. In the evolution of magnetospheric magnetic field models, cosmic ray and magnetospheric physicists should work closely together since cosmic ray measurements are a powerful additional tool in the study of the perturbed magnetosphere. In the field of cosmogenic nuclides, finally, exciting new results and developments follow in rapid succession. Thanks to new techniques and new isotopes the analysis of cosmic ray history has entered into a new dimension.

  6. Bridging the timescales between thermochronological and cosmogenic nuclide data

    NASA Astrophysics Data System (ADS)

    Glotzbach, Christoph

    2015-04-01

    Reconstructing the evolution of Earth's landscape is a key to understand its future evolution and to identify the driving forces that shape Earth's surface. Cosmogenic nuclide and thermochronological methods are routinely used to quantify Earth surface processes over 102-104 yr and 106-107 yr, respectively (e.g. Lal 1991; Reiners and Ehlers 2005; von Blanckenburg 2006). A comparison of the rates of surface processes derived from these methods is, however, hampered by the large difference in their timescales. For instance, a constant erosion rate of 0.1 mm/yr yield an apatite (U-Th)/He age of ~24 Ma and a 10Be age of ~6 ka, respectively. Analytical methods that bridge this time gap are on the way, but are not yet fully established (e.g. Herman et al. 2010). A ready to use alternative are river profiles, which record the regional uplift history over 102-107 yr (e.g. Pritchard et al. 2009). Changes in uplift are retained in knickzones that propagate with a distinct velocity upstream, and therefore the time of an uplift event can be estimated. Here I present an integrative inverse modelling approach to simultaneously reconstruct river profiles, model thermochronological and cosmogenic nuclide data and to derive robust information about landscape evolution over thousands to millions of years. An efficient inversion routine is used to solve the forward problem and find the best uplift history and erosional parameters that reproduce the observed data. I test the performance of the algorithm by inverting a synthetic dataset and a dataset from the Sila massif (Italy). Results show that even complicated uplift histories can be reliably retrieved by the combined interpretation of river profiles, thermochronological and cosmogenic nuclide data. References Gallagher, K., Brown, R. & Johnson, C. (1998): Fission track analysis and its applications to geological problems. - Annu. Rev. Earth Planet., 26: 519-572. Herman, F., Rhodes, E.J., Braun, J. & Heiniger, L. (2010): Uniform

  7. A modified direct method for the calculation of elastic moduli of composite materials

    SciTech Connect

    Wang, J.A.; Lubliner, J.; Monteiro, P.J.M.

    1996-02-01

    The modified direct method is a scheme for the estimation of elastic moduli of composite materials and is based on micromechanical theory and classical elasticity. Using the statistical homogeneous assumption and the two-phase composite approach, one takes the average field of the composite. Due to the complexity of composite materials, the modeling parameters for the exact analytical theory are not always available and then the effective bounds are usually too wide for practical application. For engineering purposes a more practical and general model is desired. The modified direct method was developed to approach the above requirements. In this work the modified direct method is compared with different available experiment data and methods, for example, Kuster-Toksoez, Christensen-Lo. The comparison results show that the modified direct method provides a very good estimation of the elastic moduli in different kinds of problems, such as the soft and hard inclusion cases, porous materials, at various concentrations and/or various porosities.

  8. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    SciTech Connect

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2, 5/2, 7/2, and 9/2. These results may be used to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistry program.

  9. The behavior of U- and Th-series nuclides in groundwater

    USGS Publications Warehouse

    Porcelli, D.; Swarzenski, P.W.

    2003-01-01

    Groundwater has long been an active area of research driven by its importance both as a societal resource and as a component in the global hydrological cycle. Key issues in groundwater research include inferring rates of transport of chemical constituents, determining the ages of groundwater, and tracing water masses using chemical fingerprints. While information on the trace elements pertinent to these topics can be obtained from aquifer tests using experimentally introduced tracers, and from laboratory experiments on aquifer materials, these studies are necessarily limited in time and space. Regional studies of aquifers can focus on greater scales and time periods, but must contend with greater complexities and variations. In this regard, the isotopic systematics of the naturally occurring radionuclides in the U- and Th- decay series have been invaluable in investigating aquifer behavior of U, Th, and Ra. These nuclides are present in all groundwaters and are each represented by several isotopes with very different half-lives, so that processes occurring over a range of time-scales can be studied (Table 1⇓). Within the host aquifer minerals, the radionuclides in each decay series are generally expected to be in secular equilibrium and so have equal activities (see Bourdon et al. 2003). In contrast, these nuclides exhibit strong relative fractionations within the surrounding groundwaters that reflect contrasting behavior during release into the water and during interaction with the surrounding host aquifer rocks. Radionuclide data can be used, within the framework of models of the processes involved, to obtain quantitative assessments of radionuclide release from aquifer rocks and groundwater migration rates. The isotopic variations that are generated also have the potential for providing fingerprints for groundwaters from specific aquifer environments, and have even been explored as a means for calculating groundwater ages.

  10. Development of an analytic procedure to calculate damage accumulation in composites during low velocity impact

    NASA Technical Reports Server (NTRS)

    Humphreys, E. A.; Goering, J.

    1983-01-01

    A computerized procedure was developed to model the response of a laminated composite plate subjected to low velocity impact. The methodology incorporated transient dynamics finite element analysis coupled with composite layer and interlaminar stress predictions. Damage was predicted using a stress based failure criteria and incorporated into the solution as stiffness modifications. The force-displacement relation between the impactor and plate was modelled with a nonlinear contact spring similar to Hertzian contact. Analyses performed predicted ply damage early in the impact event when the displacement fields were characteristic of high frequency flexurable response.

  11. Stress Free Temperature Testing and Calculations on Out-of-Autoclave Composites

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.; Tate, LeNetra C.; Danley, Susan E.; Sampson, Jeffrey W.; Taylor, Brian J.; Sutter, James K.; Miller, Sandi G.

    2013-01-01

    Future launch vehicles will require the incorporation of large composite parts that will make up primary and secondary components of the vehicle. NASA has explored the feasibility of manufacturing these large components using Out-of-Autoclave impregnated carbon fiber composite systems through many composites development projects. Most recently, the Composites for Exploration Project has been looking at the development of a 10 meter diameter fairing structure, similar in size to what will be required for a heavy launch vehicle. The development of new material systems requires the investigation of the material properties and the stress in the parts. Residual stress is an important factor to incorporate when modeling the stresses that a part is undergoing. Testing was performed to verify the stress free temperature with two-ply asymmetric panels. A comparison was done between three newly developed out of autoclave IM7/Bismaleimide (BMI) systems. This paper presents the testing results and the analysis performed to determine the stress free temperature of the materials

  12. Electron and proton absorption calculations for a graphite/epoxy composite model. [large space structures

    NASA Technical Reports Server (NTRS)

    Long, E. R., Jr.

    1979-01-01

    The Bethe-Bloch stopping power relations for inelastic collisions were used to determine the absorption of electron and proton energy in cured neat epoxy resin and the absorption of electron energy in a graphite/epoxy composite. Absorption of electron energy due to bremsstrahlung was determined. Electron energies from 0.2 to 4.0 MeV and proton energies from 0.3 to 1.75 MeV were used. Monoenergetic electron energy absorption profiles for models of pure graphite, cured neat epoxy resin, and graphite/epoxy composites are reported. A relation is determined for depth of uniform energy absorption in a composite as a function of fiber volume fraction and initial electron energy. Monoenergetic proton energy absorption profiles are reported for the neat resin model. A relation for total proton penetration in the epoxy resin as a function of initial proton energy is determined. Electron energy absorption in the composite due to bremsstrahlung is reported. Electron and proton energy absorption profiles in cured neat epoxy resin are reported for environments approximating geosynchronous earth orbit.

  13. Stress Free Temperature Testing and Residual Stress Calculations on Out-of-Autoclave Composites

    NASA Technical Reports Server (NTRS)

    Cox, Sarah; Tate, LaNetra C.; Danley, Susan; Sampson, Jeff; Taylor, Brian; Miller, Sandi

    2012-01-01

    Future launch vehicles will require the incorporation large composite parts that will make up primary and secondary components of the vehicle. NASA has explored the feasibility of manufacturing these large components using Out-of-Autoclave impregnated carbon fiber composite systems through many composites development projects. Most recently, the Composites for Exploration Project has been looking at the development of a 10 meter diameter fairing structure, similar in size to what will be required for a heavy launch vehicle. The development of new material systems requires the investigation of the material properties and the stress in the parts. Residual stress is an important factor to incorporate when modeling the stresses that a part is undergoing. Testing was performed to verify the stress free temperature with two-ply asymmetric panels. A comparison was done between three newly developed out of autoclave IM7 /Bismalieimide (BMI) systems. This paper presents the testing results and the analysis performed to determine the residual stress of the materials.

  14. Computer program for calculation of complex chemical equilibrium compositions and applications. Part 1: Analysis

    NASA Technical Reports Server (NTRS)

    Gordon, Sanford; Mcbride, Bonnie J.

    1994-01-01

    This report presents the latest in a number of versions of chemical equilibrium and applications programs developed at the NASA Lewis Research Center over more than 40 years. These programs have changed over the years to include additional features and improved calculation techniques and to take advantage of constantly improving computer capabilities. The minimization-of-free-energy approach to chemical equilibrium calculations has been used in all versions of the program since 1967. The two principal purposes of this report are presented in two parts. The first purpose, which is accomplished here in part 1, is to present in detail a number of topics of general interest in complex equilibrium calculations. These topics include mathematical analyses and techniques for obtaining chemical equilibrium; formulas for obtaining thermodynamic and transport mixture properties and thermodynamic derivatives; criteria for inclusion of condensed phases; calculations at a triple point; inclusion of ionized species; and various applications, such as constant-pressure or constant-volume combustion, rocket performance based on either a finite- or infinite-chamber-area model, shock wave calculations, and Chapman-Jouguet detonations. The second purpose of this report, to facilitate the use of the computer code, is accomplished in part 2, entitled 'Users Manual and Program Description'. Various aspects of the computer code are discussed, and a number of examples are given to illustrate its versatility.

  15. Computer program for calculation of complex chemical equilibrium compositions and applications. Supplement 1: Transport properties

    NASA Technical Reports Server (NTRS)

    Gordon, S.; Mcbride, B.; Zeleznik, F. J.

    1984-01-01

    An addition to the computer program of NASA SP-273 is given that permits transport property calculations for the gaseous phase. Approximate mixture formulas are used to obtain viscosity and frozen thermal conductivity. Reaction thermal conductivity is obtained by the same method as in NASA TN D-7056. Transport properties for 154 gaseous species were selected for use with the program.

  16. Computer program for calculation of complex chemical equilibrium compositions and applications. Supplement 1: Transport properties

    NASA Astrophysics Data System (ADS)

    Gordon, S.; McBride, B.; Zeleznik, F. J.

    1984-10-01

    An addition to the computer program of NASA SP-273 is given that permits transport property calculations for the gaseous phase. Approximate mixture formulas are used to obtain viscosity and frozen thermal conductivity. Reaction thermal conductivity is obtained by the same method as in NASA TN D-7056. Transport properties for 154 gaseous species were selected for use with the program.

  17. Extension of the composite CBS-QB3 method to singlet diradical calculations

    NASA Astrophysics Data System (ADS)

    Sirjean, Baptiste; Fournet, René; Glaude, Pierre-Alexandre; Ruiz-López, Manuel F.

    2007-02-01

    The composite CBS-QB3 method is widely used to obtain accurate energies of molecules and radicals although its use in the case of singlet diradicals gives rise to some difficulties. The problem is related to the parameterized correction this method introduces to account for spin-contamination. We report a new term specifically designed to describe singlet diradicals separated by at least one CH 2 unit. As a test case, we have computed the formation enthalpy of a series of diradicals that includes hydrocarbons as well as systems involving heteroatoms (nitrogen, oxygen). The resulting CBS-QB3 energies are very close to experiment.

  18. Ortho- and clinopyroxene compositions in ordinary chondrites and related blander model calculation procedures

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Olsen, E.

    1973-01-01

    Chemical analyses of the orthopyroxene and clinopyroxene compositions in chondrites are reported. Standard microprobe techniques to 15 kilovolts, 0.03 microamperes, and 40 second counting time were employed. Duplicate analyses were conducted on three grains of each opx and cpx together with two different raw data correction methods as checks on analytical precision and correction procedures. Only those analytical summations of between 99.20 and 100.80 weight percent, and cation summations between 3.980 and 4.020 (based on 6 oxygens) were used.

  19. Frequency and duration calculations in composite generation and transmission reliability evaluation

    SciTech Connect

    Melo, A.C.G.; Pereira, M.V.F. ); da Silva, A.M. . Research Center)

    1992-05-01

    This paper presents a new methodology for frequency and duration (F and D) assessment in composite generation and transmission reliability evaluation. The F and D indices are obtained from a nonsequential Monte Carlo simulation scheme. Computational effort is reduced by using the Lagrange multipliers associated to the adequacy assessment of each state to identify the boundary wall between failure and success states. The methodology is illustrated in case studies with the IEEE test system and two utility-derived system. The proposed approach allows the practical application of F and D indices in integrated generation/transmission planning studies.

  20. An Approach to Calculate Mineralś Bulk Moduli KS from Chemical Composition and Density ρ

    NASA Astrophysics Data System (ADS)

    Breuer, S.; Schilling, F. R.; Mueller, B.; Drüppel, K.

    2015-12-01

    The elastic properties of minerals are fundamental parameters for technical and geotechnical applications and an important research topic towards a better understanding of the Earth's interior. Published elastic properties, chemical composition, and density data of 86 minerals (total of 258 data including properties of minerals at various p, T conditions) were collected into a database. It was used to test different hypotheses about relationships between these properties (e.g. water content in minerals and their Poisson's ratio). Furthermore, a scheme to model the average elastic properties, i.e. the bulk modulus KS, based on mineral density and composition was developed. Birch's law, a linearity between density ρ and wave velocity (e.g. vp.), is frequently used in seismic and seismology to derive density of the Earth's interior from seismic velocities. Applying the compiled mineral data contradicts the use of a simple velocity-density relation (e.g. Gardneŕs relation, 1974). The presented model-approach to estimate the mineralś bulk moduli Ks (as Voigt-Reuss-Hill average) is based on the idea of pressure-temperature (p-T) dependent ionś bulk moduli. Using a multi-exponential regression to ascertain the ionś bulk moduli and by applying an exponential scaling with density ρ, their bulk moduli could be modelled. As a result, > 88 % of the 258 bulk moduli data are predicted with an uncertainty of < 20 % compared to published values. Compared to other models (e.g. Anderson et al. 1970 and Anderson & Nafe 1965), the here presented approach to model the bulk moduli only requires the density ρ and chemical composition of the mineral and is not limited to a specific group of minerals, composition, or structure. In addition to this, by using the pressure and temperature dependent density ρ(p, T), it is possible to predict bulk moduli for varying p-T conditions. References:Gardner, G.H.F, Gardner, L.W. and Gregory, A.R. (1974). Geophysics, 39, No. 6, 770

  1. Exo-Transmit: An Open-Source Code for Calculating Transmission Spectra for Exoplanet Atmospheres of Varied Composition

    NASA Astrophysics Data System (ADS)

    Kempton, Eliza M.-R.; Lupu, Roxana; Owusu-Asare, Albert; Slough, Patrick; Cale, Bryson

    2017-04-01

    We present Exo-Transmit, a software package to calculate exoplanet transmission spectra for planets of varied composition. The code is designed to generate spectra of planets with a wide range of atmospheric composition, temperature, surface gravity, and size, and is therefore applicable to exoplanets ranging in mass and size from hot Jupiters down to rocky super-Earths. Spectra can be generated with or without clouds or hazes with options to (1) include an optically thick cloud deck at a user-specified atmospheric pressure or (2) to augment the nominal Rayleigh scattering by a user-specified factor. The Exo-Transmit code is written in C and is extremely easy to use. Typically the user will only need to edit parameters in a single user input file in order to run the code for a planet of their choosing. Exo-Transmit is available publicly on Github with open-source licensing at https://github.com/elizakempton/Exo_Transmit.

  2. Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

    PubMed Central

    Wéry, Jany; Duvail, Jean-Luc; Lefrant, Serge; Yaya, Abu; Ewels, Chris

    2015-01-01

    Summary The mechanisms that control the photophysics of composite films made of a semiconducting conjugated polymer (poly(paraphenylene vinylene), PPV) mixed with single-walled carbon nanotubes (SWNT) up to a concentration of 64 wt % are determined by using photoexcitation techniques and density functional theory. Charge separation is confirmed experimentally by rapid quenching of PPV photoluminescence and changes in photocurrent starting at relatively low concentrations of SWNT. Calculations predict strong electronic interaction between the polymer and the SWNT network when nanotubes are semiconducting. PMID:26171290

  3. Efficient homogenization procedure for the calculation of optical properties of 3D nanostructured composites.

    PubMed

    Mochan, W Luis; Ortiz, Guillermo P; Mendoza, Bernardo S

    2010-10-11

    We present a very efficient recursive method to calculate the effective optical response of metamaterials made up of arbitrarily shaped inclusions arranged in periodic 3D arrays. We apply it to dielectric particles embedded in a metal matrix with a lattice constant much smaller than the wavelength of the incident field, so that we may neglect retardation and factor the geometrical properties from the properties of the materials. If the conducting phase is continuous the low frequency behavior is metallic, and if the conducting paths are thin, the high frequency behavior is dielectric. Thus, extraordinary-transparency bands may develop at intermediate frequencies, whose properties may be tuned by geometrical manipulation.

  4. A Novel Method for Calculation of Strain Energy Release Rate of Asymmetric Double Cantilever Laminated Composite Beams

    NASA Astrophysics Data System (ADS)

    Shokrieh, M. M.; Zeinedini, A.

    2014-06-01

    In this research, a novel data reduction method for calculation of the strain energy release rate ( SERR) of asymmetric double cantilever beams ( ADCB) is presented. For this purpose the elastic beam theory ( EBT) is modified and the new method is called as the modified elastic beam theory ( MEBT). Also, the ADCB specimens are modeled using ABAQUS/Standard software. Then, the initiation of delamination of ADCB specimens is modeled using the virtual crack closure technique ( VCCT). Furthermore, magnitudes of the SERR for different samples are also calculated by an available data reduction method, called modified beam theory ( MBT). Using the hand lay-up method, different laminated composite samples are manufactured by E-glass/epoxy unidirectional plies. In order to measure the SERR, all samples are tested using an experimental setup. The results determined by the new data reduction method ( MEBT) show good agreements with the results of the VCCT and the MBT.

  5. Gamow-Teller strength in the beta decay of mirror nuclides

    NASA Astrophysics Data System (ADS)

    Honkanen, J.; ńystö, J.; Koponen, V.; Taskinen, P.; Eskola, K.; Messelt, S.; Ogawa, K.

    1987-12-01

    Distribution of the Gamow-Teller strength has been studied both experimentally and theoretically in the f7/2 shell mirror nuclides over a wide energy range. Experimental studies were performed using light ion induced reactions and the He-jet transport method or the ion-guide on-line isotope separation, IGISOL. Several transitions were observed to excited states in the decays of 43Ti and 51Fe and some in the decays of 47Cr, 49Mn, 43Co and 55Ni. Theoretical calculations were made by a shell model code using fn7/2+(P3/2, f5/2, P1/2)1 shell space. The β-feeding has been predicted for all transitions up to about 4 MeV excitation in each daughter nucleus. The quenching of the Gamow-Teller strength has been studied by comparing the experimental strength with the calculation. The formation of the giant Gamow-Teller resonance has been studied theoretically as a function of the mass number.

  6. Calculation of skin-stiffener interface stresses in stiffened composite panels

    NASA Technical Reports Server (NTRS)

    Cohen, David; Hyer, Michael W.

    1987-01-01

    A method for computing the skin-stiffener interface stresses in stiffened composite panels is developed. Both geometrically linear and nonlinear analyses are considered. Particular attention is given to the flange termination region where stresses are expected to exhibit unbounded characteristics. The method is based on a finite-element analysis and an elasticity solution. The finite-element analysis is standard, while the elasticity solution is based on an eigenvalue expansion of the stress functions. The eigenvalue expansion is assumed to be valid in the local flange termination region and is coupled with the finite-element analysis using collocation of stresses on the local region boundaries. Accuracy and convergence of the local elasticity solution are assessed using a geometrically linear analysis. Using this analysis procedure, the influence of geometric nonlinearities and stiffener parameters on the skin-stiffener interface stresses is evaluated.

  7. Nuclide identification algorithm based on K-L transform and neural networks

    NASA Astrophysics Data System (ADS)

    Chen, Liang; Wei, Yi-Xiang

    2009-01-01

    Traditional spectrum analysis algorithm based on peak search is hard to deal with complex overlapped peaks, especially in bad resolution and high background conditions. This paper described a new nuclide identification method based on the Karhunen-Loeve transform (K-L transform) and artificial neural networks. By the K-L transform and feature extraction, the nuclide gamma spectrum was compacted. The K-L transform coefficients were used as the neural network's input. The linear associative memory and ADALINE were discussed. Lots of experiments and tests showed that the method was credible and practical, especially suitable for fast nuclide identification.

  8. Fission barriers at the end of the chart of the nuclides

    SciTech Connect

    Möller, Peter; Sierk, Arnold J.; Ichikawa, Takatoshi; Iwamoto, Akira; Mumpower, Matthew

    2015-02-12

    We present calculated fission-barrier heights for 5239 nuclides for all nuclei between the proton and neutron drip lines with 171 ≤ A ≤ 330. The barriers are calculated in the macroscopic-microscopic finite-range liquid-drop (FRLDM) with a 2002 set of macroscopic-model parameters. The saddle-point energies are determined from potential-energy surfaces based on more than five million different shapes, defined by five deformation parameters in the three-quadratic-surface shape parametrization: elongation, neck diameter, left-fragment spheroidal deformation, right-fragment spheroidal deformation, and nascent-fragment mass asymmetry. The energy of the ground state is determined by calculating the lowest-energy configuration in both the Nilsson perturbed-spheroid (ϵ) and the spherical-harmonic (β) parametrizations, including axially asymmetric deformations. The lower of the two results (correcting for zero-point motion) is defined as the ground-state energy. The effect of axial asymmetry on the inner barrier peak is calculated in the (ϵ,γ) parametrization. We have earlier benchmarked our calculated barrier heights to experimentally extracted barrier parameters and found average agreement to about one MeV for known data across the nuclear chart. Here we do additional benchmarks and investigate the qualitative and, when possible, quantitative agreement and/or consistency with data on β-delayed fission, isotope generation along prompt-neutron-capture chains in nuclear-weapons tests, and superheavy-element stability. In addition these studies all indicate that the model is realistic at considerable distances in Z and N from the region of nuclei where its parameters were determined.

  9. Fission barriers at the end of the chart of the nuclides

    NASA Astrophysics Data System (ADS)

    Möller, Peter; Sierk, Arnold J.; Ichikawa, Takatoshi; Iwamoto, Akira; Mumpower, Matthew

    2015-02-01

    We present calculated fission-barrier heights for 5239 nuclides for all nuclei between the proton and neutron drip lines with 171 ≤A ≤330 . The barriers are calculated in the macroscopic-microscopic finite-range liquid-drop model with a 2002 set of macroscopic-model parameters. The saddle-point energies are determined from potential-energy surfaces based on more than 5 000 000 different shapes, defined by five deformation parameters in the three-quadratic-surface shape parametrization: elongation, neck diameter, left-fragment spheroidal deformation, right-fragment spheroidal deformation, and nascent-fragment mass asymmetry. The energy of the ground state is determined by calculating the lowest-energy configuration in both the Nilsson perturbed-spheroid (ɛ ) and the spherical-harmonic (β ) parametrizations, including axially asymmetric deformations. The lower of the two results (correcting for zero-point motion) is defined as the ground-state energy. The effect of axial asymmetry on the inner barrier peak is calculated in the (ɛ ,γ ) parametrization. We have earlier benchmarked our calculated barrier heights to experimentally extracted barrier parameters and found average agreement to about 1 MeV for known data across the nuclear chart. Here we do additional benchmarks and investigate the qualitative and, when possible, quantitative agreement and/or consistency with data on β -delayed fission, isotope generation along prompt-neutron-capture chains in nuclear-weapons tests, and superheavy-element stability. These studies all indicate that the model is realistic at considerable distances in Z and N from the region of nuclei where its parameters were determined.

  10. Fission barriers at the end of the chart of the nuclides

    DOE PAGES

    Möller, Peter; Sierk, Arnold J.; Ichikawa, Takatoshi; ...

    2015-02-12

    We present calculated fission-barrier heights for 5239 nuclides for all nuclei between the proton and neutron drip lines with 171 ≤ A ≤ 330. The barriers are calculated in the macroscopic-microscopic finite-range liquid-drop (FRLDM) with a 2002 set of macroscopic-model parameters. The saddle-point energies are determined from potential-energy surfaces based on more than five million different shapes, defined by five deformation parameters in the three-quadratic-surface shape parametrization: elongation, neck diameter, left-fragment spheroidal deformation, right-fragment spheroidal deformation, and nascent-fragment mass asymmetry. The energy of the ground state is determined by calculating the lowest-energy configuration in both the Nilsson perturbed-spheroid (ϵ) andmore » the spherical-harmonic (β) parametrizations, including axially asymmetric deformations. The lower of the two results (correcting for zero-point motion) is defined as the ground-state energy. The effect of axial asymmetry on the inner barrier peak is calculated in the (ϵ,γ) parametrization. We have earlier benchmarked our calculated barrier heights to experimentally extracted barrier parameters and found average agreement to about one MeV for known data across the nuclear chart. Here we do additional benchmarks and investigate the qualitative and, when possible, quantitative agreement and/or consistency with data on β-delayed fission, isotope generation along prompt-neutron-capture chains in nuclear-weapons tests, and superheavy-element stability. In addition these studies all indicate that the model is realistic at considerable distances in Z and N from the region of nuclei where its parameters were determined.« less

  11. An Analytical Investigation of Three General Methods of Calculating Chemical-Equilibrium Compositions

    NASA Technical Reports Server (NTRS)

    Zeleznik, Frank J.; Gordon, Sanford

    1960-01-01

    The Brinkley, Huff, and White methods for chemical-equilibrium calculations were modified and extended in order to permit an analytical comparison. The extended forms of these methods permit condensed species as reaction products, include temperature as a variable in the iteration, and permit arbitrary estimates for the variables. It is analytically shown that the three extended methods can be placed in a form that is independent of components. In this form the Brinkley iteration is identical computationally to the White method, while the modified Huff method differs only'slightly from these two. The convergence rates of the modified Brinkley and White methods are identical; and, further, all three methods are guaranteed to converge and will ultimately converge quadratically. It is concluded that no one of the three methods offers any significant computational advantages over the other two.

  12. Comparison of measured and calculated composition of irradiated EBR-II blanket assemblies.

    SciTech Connect

    Grimm, K. N.

    1998-07-13

    In anticipation of processing irradiated EBR-II depleted uranium blanket subassemblies in the Fuel Conditioning Facility (FCF) at ANL-West, it has been possible to obtain a limited set of destructive chemical analyses of samples from a single EBR-II blanket subassembly. Comparison of calculated values with these measurements is being used to validate a depletion methodology based on a limited number of generic models of EBR-II to simulate the irradiation history of these subassemblies. Initial comparisons indicate these methods are adequate to meet the operations and material control and accountancy (MC and A) requirements for the FCF, but also indicate several shortcomings which may be corrected or improved.

  13. Sequential multi-nuclide emission rate estimation method based on gamma dose rate measurement for nuclear emergency management.

    PubMed

    Zhang, Xiaole; Raskob, Wolfgang; Landman, Claudia; Trybushnyi, Dmytro; Li, Yu

    2017-03-05

    In case of a nuclear accident, the source term is typically not known but extremely important for the assessment of the consequences to the affected population. Therefore the assessment of the potential source term is of uppermost importance for emergency response. A fully sequential method, derived from a regularized weighted least square problem, is proposed to reconstruct the emission and composition of a multiple-nuclide release using gamma dose rate measurement. The a priori nuclide ratios are incorporated into the background error covariance (BEC) matrix, which is dynamically augmented and sequentially updated. The negative estimations in the mathematical algorithm are suppressed by utilizing artificial zero-observations (with large uncertainties) to simultaneously update the state vector and BEC. The method is evaluated by twin experiments based on the JRodos system. The results indicate that the new method successfully reconstructs the emission and its uncertainties. Accurate a priori ratio accelerates the analysis process, which obtains satisfactory results with only limited number of measurements, otherwise it needs more measurements to generate reasonable estimations. The suppression of negative estimation effectively improves the performance, especially for the situation with poor a priori information, where it is more prone to the generation of negative values. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Fuel Thermo-physical Characterization Project: Evaluation of Models to Calculate Thermal Diffusivity of Layered Composites

    SciTech Connect

    Burkes, Douglas; Casella, Amanda J.; Gardner, Levi D.; Casella, Andrew M.; Huber, Tanja K.; Breitkreutz, Harald

    2015-02-11

    The Office of Material Management and Minimization Fuel Thermo-physical Characterization Project at Pacific Northwest National Laboratory (PNNL) is tasked with using PNNL facilities and processes to receive irradiated low enriched uranium-molybdenum fuel plate samples and perform analyses in support of the Office of Material Management and Minimization Reactor Conversion Program. This work is in support of the Fuel Development Pillar that is managed by Idaho National Laboratory. A key portion of the scope associated with this project was to measure the thermal properties of fuel segments harvested from plates that were irradiated in the Advanced Test Reactor. Thermal diffusivity of samples prepared from the fuel segments was measured using laser flash analysis. Two models, one developed by PNNL and the other developed by the Technische Universität München (TUM), were evaluated to extract the thermal diffusivity of the uranium-molybdenum alloy from measurements made on the irradiated, layered composites. The experimental data of the “TC” irradiated fuel segment was evaluated using both models considering a three-layer and five-layer system. Both models are in acceptable agreement with one another and indicate that the zirconium diffusion barrier has a minimal impact on the overall thermal diffusivity of the monolithic U-Mo fuel.

  15. Measurement of the yield of nuclides produced in the interaction of 1-GeV protons with a cylindrical lead target

    SciTech Connect

    Bakhmutkin, S.V.; Nosov, A.A.; Rimskii-Korsakov, A.A.

    1988-02-01

    In the last few years, the yield of nuclides produced in spallation and fission reactions by high-energy protons bombarding heavy-element targets with dimensions close to the path length has been determined. The development of computational techniques describing the nuclear cascade in such targets calls for a comparison with experimental results obtained in a relatively simple geometry. The goal of the present work was to obtain experimental data for selecting and correcting the parameters to be used in the calculations. The distributions were used to determine the yield of 22 nuclides for a cylindrical lead target with a diameter of 200 mm and a length of 600 mm; the distributions were expressed by the activity in saturation, induced by a primary proton beam with a current of 1 nA. The results of this determination are listed.

  16. Modified microspheres for cleaning liquid wastes from radioactive nuclides

    SciTech Connect

    Danilin, Lev; Drozhzhin, Valery

    2007-07-01

    An effective solution of nuclear industry problems related to deactivation of technological and natural waters polluted with toxic and radioactive elements is the development of inorganic sorbents capable of not only withdrawing radioactive nuclides, but also of providing their subsequent conservation under conditions of long-term storage. A successful technical approach to creation of sorbents can be the use of hollow aluminosilicate microspheres. Such microspheres are formed from mineral additives during coal burning in furnaces of boiler units of electric power stations. Despite some reduction in exchange capacity per a mass unit of sorbents the latter have high kinetic characteristics that makes it possible to carry out the sorption process both in static and dynamic modes. Taking into account large industrial resources of microspheres as by-products of electric power stations, a comparative simplicity of the modification process, as well as good kinetic and capacitor characteristics, this class of sorbents can be considered promising enough for solving the problems of cleaning liquid radioactive wastes of various pollution levels. (authors)

  17. A new paleoaltimeter using multiple radioactive cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    Blard, Pierre-Henri; Lupker, Maarten; Rousseau, Moïse

    2017-04-01

    Determining absolute paleoaltitudes over geological timescales is one of the most challenging issues in Earth Sciences. We present here the theoretical basis of a new paleoaltimetric approach, based on the analysis of at least two cosmogenic nuclides with different radioactive decay, that have been produced in paleo-exposed surfaces. Applying this method to the existing 21Ne-10Be-26Al datasets in the dry Andes shows a very good agreement between the computed and the sampling elevations. Limitations and uncertainties of our new approach are evaluated using several numerical simulations. In many cases, the uncertainty at the 1-sigma level will be lower than 1000 m. The two main advantages of this method are i) the computed altitude is almost insensitive to the impact of erosion and ii) it does not require an independent determination of the duration of the paleo-exposure. However it has the inconvenient to require long paleoexposure (> 500 ka), which can be difficult to find in fast eroding mountainous environments.

  18. International program to improve decay data for transactinium nuclides

    NASA Astrophysics Data System (ADS)

    Helmer, R. G.; Reich, C. W.

    To help meet an identified need for precise decay data, in 1977 an international coordinated research program (CRP) to measure and evaluate half-lives and gamma (-) and alpha (-) emission probabilities for selected transactinium nuclides of importance for reactor technology was organized. The CRP goals were: (1) to determine a list of data that needed improvement, (2) to encourage new measurements, and (3) to evaluate the available data. All three phases of this work are now complete. Participation in this effort involved the measurement of gamma-ray emission probabilities for sup 232, 233, 235 U, sup 238, 239, 240. 241 Pu, (229)Th and (233)Pa, as well as participating in the data evaluation. The gamma-emission probabilities were determined from the measurement of gamma-emission rates with the goal of obtaining uncertainties of less than or equal to 1%. Measurements were made on calibrated Ge detectors. These calibrations were done by standard methods, generally involving measurements at approx. 60 gamma-ray energies from 14 to 2700 keV. The efficiency-calibration functions were assigned uncertainties ranging from 2% below 50 keV to 0.50% from 400 to 1400 keV. The determination of the decay rates of the various sources involved several techniques.

  19. Self-consistent calculation of the nuclear composition in hot and dense stellar matter

    NASA Astrophysics Data System (ADS)

    Furusawa, Shun; Mishustin, Igor

    2017-03-01

    We investigate the mass fractions and in-medium properties of heavy nuclei in stellar matter at characteristic densities and temperatures for supernova (SN) explosions. The individual nuclei are described within the compressible liquid-drop model taking into account modifications of bulk, surface, and Coulomb energies. The equilibrium properties of nuclei and the full ensemble of heavy nuclei are calculated self-consistently. It is found that heavy nuclei in the ensemble are either compressed or decompressed depending on the isospin asymmetry of the system. The compression or decompression has a little influence on the binding energies, total mass fractions, and average mass numbers of heavy nuclei, although the equilibrium densities of individual nuclei themselves are changed appreciably above one-hundredth of normal nuclear density. We find that nuclear structure in the single-nucleus approximation deviates from the actual one obtained in the multinucleus description, since the density of free nucleons is different between these two descriptions. This study indicates that a multinucleus description is required to realistically account for in-medium effects on the nuclear structure in supernova matter.

  20. Recommended Partition Coefficient (Kd) Values for Nuclide Partitioning in the Presence of Cellulose Degradation Products

    SciTech Connect

    Serkiz, S.M.

    2001-02-23

    This report documents the data analysis of the results of the described laboratory studies in order to recommend Kd values for use in Performance Assessment modeling of nuclide transport in the presence of CDP.

  1. Calculation of optical properties of dental composites as a basis for determining color impression and penetration depth of laser light

    NASA Astrophysics Data System (ADS)

    Weniger, Kirsten K.; Muller, Gerhard J.

    2005-03-01

    In order to achieve esthetic dental restorations, there should be no visible difference between restorative material and treated teeth. This requires a match of the optical properties of both restorative material and natural teeth. These optical properties are determined by absorption and scattering of light emerging not only on the surface but also inside the material. Investigating different dental composites in several shades, a method has been developed to calculate the optical parameters absorption coefficient μa, scattering coefficient μs, anisotropy factor g and reduced scattering coefficient μs'. The method includes sample preparation and measurements of transmittance and reflectance in an integrating sphere spectrometer, followed by inverse Monte Carlo simulations. Determination of optical properties is more precise and comprehensive than with the previously used Kubelka Munk theory because scattering can be looked at separated into pure scattering with the scattering coefficient μs and its direction with the anisotropy factor g. Moreover the use of the inverse Monte Carlo simulation not only minimizes systematic errors and considers the scattering phase function, but also takes into account the measuring geometry. The compilation of a data pool of optical parameters now enables the application of further calculation models as a basis for optimization of the composition of new materials. For example, a prediction of the general color impression for multiple layers can be carried out as well as the calculation of the wavelength dependent penetration depths of light with regard to photo polymerization. Further applications are possible in the area of laser ablation.

  2. Phase II Nuclide Partition Laboratory Study Influence of Cellulose Degradation Products on the Transport of Nuclides from SRS Shallow Land Burial Facilities

    SciTech Connect

    Serkiz, S.M.

    1999-10-04

    Degradation products of cellulosic materials (e.g., paper and wood products) can significantly influence the subsurface transport of metals and radionuclides. Codisposal of radionuclides with cellulosic materials in the E-Area slit trenches at the Savannah River Site (SRS) is, therefore, expected to influence nuclide fate and transport in the subsurface. Due to the complexities of these systems and the scarcity of site-specific data, the effects of cellulose waste loading and its subsequent influence on nuclide transport are not well established.

  3. Investigation of Naturally Occurring Radio Nuclides in Shir-kuh Granites

    SciTech Connect

    Mazarei, Mohammad Mehdi; Zarei, Mojtaba

    2011-12-26

    One of the principle natural radiation resources is Granite which can be dangerous for human because of its radiations. Based on this fact, in this research we attempt to specify the activity amount of these natural radio nuclides, existing in Shir-kuh Granite of Yazd state. To specify the activity amount of this natural radio nuclides, it has been applied the measurement method of Gamma spectroscopy using high purity Germanium (HPGe) detector.

  4. Measurements of Cosmogenic Nuclides in and their Significance for Samples Returned from Asteroids

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Herzog, G. F.; Reedy, R. C.

    2000-01-01

    Nuclear interactions of cosmic rays with matter produce cosmogenic nuclides (CNs). Ever since they were first measured nearly 50 years ago, cosmogenic nuclides have been used to infer the irradiation histories of terrestrial and extraterrestrial materials. Here we call for an extension of such measurements to samples returned from an asteroidal surface. The information gained in this way will be important for elucidating the evolution of the asteroidal surface. Additional information is contained in the original extended abstract.

  5. Global sediment production from in-situ cosmogenic nuclides in large river basins

    NASA Astrophysics Data System (ADS)

    Haedke, H.; Wittmann, H.; von Blanckenburg, F.; Gaillardet, J.

    2016-12-01

    The worlds 30 largest rivers represent half of the total runoff to the ocean and thus integrate the fluxes of Earth surface weathering and erosion over a large portion of global tectonic, geomorphic, and climatic zones. In-situ produced cosmogenic nuclides (10Be, 26Al) in detrital quartz sand can be used to constrain the mean millennial-scale denudation of these large basins. Yet cosmogenic nuclides have mostly been applied to small and intermediate size basins of significant relief. One reason is that in these settings, lowland sediment storage and burial are short compared to the half life of the nuclide (e.g. 1.4 Myr for 10Be). However, if sediment storage is long compared to the half-life, paired nuclides (e.g. 26Al/10Be), through their differential decay, allow to assess the duration of sediment transfer and burial ages from source to sink[1]. Here we present a new dataset of cosmogenic nuclides from 60 large rivers that integrate over 30% of Earth's terrestrial surface. 26Al/10Be ratios of around 6 to 7.5 for most rivers reveal burial durations shorter than the nuclides' decay time scales, indicating high source-sink connectivity. In slowly-eroding basins such as the tectonically quiescent Australian Murray-Darling or the central African Okavango and Congo rivers, 26Al/10Be ratios of <6 indicate decay of nuclide concentrations. Such low nuclide ratios evolve during Myr-scale sediment burial during slow source to sink transfer. We converted denudation rates to sediment fluxes by estimating their actively eroding source areas. Extrapolating these millennial-scale sediment fluxes to global source areas provides an estimate of the global sediment flux. The comparison with estimates of modern sediment fluxes from river load gauging offers to deciphering the controls of sediment generation versus sediment transport across large basins. [1] Wittmann and von Blanckenburg (2016), Earth Science Reviews, 159,118-141.

  6. Using cosmogenic nuclides from amalgamated talus cobbles to assess alpine erosion in the Teton Range

    NASA Astrophysics Data System (ADS)

    Tranel, L. M.

    2014-12-01

    Measuring spatial patterns and rates of erosion in alpine landscapes is challenging because locations are steep and remote, and hillslope processes including rockfalls, avalanches and landslides are stochastic. This study evaluates how variability between quantitative erosion rates and surface ages and qualitative weathering features on talus deposits may influence interpretations of the spatial distribution of hillslope erosion in the Teton Range. I use cosmogenic nuclide concentrations to estimate erosion rates and surface ages of bedrock and talus deposits. I then compare these cosmogenic nuclide results to talus volumetric estimates of erosion rates. I also compare the quantitative estimates of surface ages and erosion to qualitative weathering observations on talus cobbles. The resulting erosion rates from cosmogenic nuclides are slower than rates estimated from talus volumes, however, both methods produced the same pattern of erosion. The fastest and slowest cosmogenic nuclide and volumetric erosion rates were associated with the same fans. Exposure ages of talus surfaces decrease as elevation of the fans increase. Qualitative observations of weathering on cobble surfaces were not reliable to predict the relative rates of erosion on the talus fans. Using amalgamated samples from hillslope deposits adjacent to steep sided canyons for cosmogenic nuclide analysis has high uncertainty when finding accurate erosion rates or exposure ages due to complicated shielding on steeply sloping walls. The similar patterns of rapid or slow erosion rates, however, suggest that cosmogenic nuclides or volume estimates are both reasonable methods to understand relative timing of hillslope events, even if the absolute age or erosion rate cannot be determined.

  7. β-decay studies of nuclides in the ^100Sn region at NSCL

    NASA Astrophysics Data System (ADS)

    Lorusso, Giuseppe; Amthor, Alan; Baumann, Thomas; Bazin, Daniel; Becerril, Ana; Crawford, Heather; Estrade, Alfredo; Gade, Alexandra; Ginter, Thomas; Guess, Carol; Hausmann, Mark; Hitt, Wes; Mantica, Paul; Matos, Milan; Meharchand, Rianon; Minamisono, Kei; Montes, Fernando; Perdikakis, Giorgios; Pereira, Jorque; Pinter, Jill; Portillo, Mauritio; Schatz, Hendrik

    2008-10-01

    β-decay nuclides in the immediate neighborhood of ^100Sn, were studied at NSCL using the β-Counting system (BCS) and the Segmented Germanium Array (SeGA). The nuclei of interest were implanted into the BCS double-sided silicon strip detector and properties from both implantations and the subsequent β-decays were recorded on an event-by-event basis, allowing for the direct observation of the half-lives and the β-delayed proton emission branching ratios. The BCS also contains a stack of Si detectors and a Ge planar detector downstream of the implantation detector to measure the total energy of the emitted beta particles, and hence the β-decay end-point energy. The properties of those nuclei are not only relevant for rp-process calculations but also are essential to understand the structure of the single particle states far from the line of stability, providing stringent tests of nuclear models in this region.

  8. (1) Selective separation and solidification of radioactive nuclides by zeolites

    NASA Astrophysics Data System (ADS)

    Mimura, Hitoshi; Sato, Nobuaki; Kirishima, Akira

    Massive tsunami generated by the Great East Japan Earthquake attacked the Fukushima Daiichi Nuclear Power Plant and caused the nuclear accident of level 7 to overturn the safety myth of the nuclear power generation. The domestic worst accident does not yet reach the convergence, and many inhabitants around the power plant are forced to double pains of earthquake disaster and nuclear accident. Large amounts of high-activity-level water over 200,000 tons are accumulated on the basement floor of each turbine building, which is a serious obstacle to take measures for the nuclear accident. For the decontamination of high-activity-level water containing seawater, the inorganic ion-exchangers having high selectivity are effective especially for the selective removal of radioactive Cs. On the other hand, radioactive Cs and I released into the atmosphere from the power plant spread widely around Fukushima prefecture, and the decontamination of rainwater and soil become the urgent problem. At present, passing about four months after nuclear accident, the radioactive nuclides of 137Cs and 134Cs are mainly contained in the high-activity-level water and the selective adsorbents for radioactive Cs play an important part in the decontamination. Since the construction of original decontamination system is an urgent necessity, selective separation methods using inorganic ion-exchangers are greatly expected. From the viewpoint of cost efficiency and high Cs-selectivity, natural zeolites are effective for the decontamination of radioactive Cs. This special issue deals with the selective separation and solidification of radioactive Cs and Sr using zeolites.

  9. International program to improve decay data for transactinium nuclides

    NASA Astrophysics Data System (ADS)

    Helmer, R. G.; Reich, C. W.

    1986-01-01

    To help meet an identified need for precise decay data, in 1977 the IAEA organized an international Coordinated Research Program (CRP) to measure and evaluate half-lives and γ- and α-emission probabilities for selected transactinium nuclides of importance for reactor technology. The CRP goals were (1) to determine a list of data that needed improvement, (2) to encourage new measurements, and (3) to evaluate the available data. All three phases of this work are now complete. Our participation in this effort has involved the measurement of γ-ray emission probabilities for 232,233,235U, 238,239,240,241Pu, 229Th and 233Pa, as well as participating in the data evaluation. The γ-emission probabilities were determined from the measurement of γ-emission rates with the goal of obtaining uncertainties of ≤ 1%. γ-measurements were made on calibrated Ge detectors. These calibrations were done by standard methods, generally involving measurements at ˜ 60 γ-ray energies from 14 to 2700 keV. The efficiency-calibration functions were assigned uncertainties ranging from 2% below 50 keV to 0.50% from 400 to 1400 keV. The determination of the decay rates of the various sources involved several techniques. The 238Pu, 239Pu and 240Pu samples were calibrated by gross α-emission-rate measurements at NBS. The 235U sample was taken from an NBS-calibrated spike solution. The 241Pu and 233U samples were calibrated by isotope-dilution mass spectrometry based on spikes of the calibrated 239Pu, 240Pu and 235U materials. Some of our results are given, together with a comparison of some present and previous results.

  10. Development of mathematical models and methods for calculation of rail steel deformation resistance of various chemical composition

    NASA Astrophysics Data System (ADS)

    Umansky, A. A.; Golovatenko, A. V.; Kadykov, V. N.; Dumova, L. V.

    2016-09-01

    Using the device of the complex “Gleeble System 3800” the physical experimental studies of deformation resistance of chrome rail steel at different thermo-mechanical deformation parameters were carried out. On the basis of mathematical processing of experimental data the statistical model of dependence of the rail steel deformation resistance on the simultaneous influence of deformation degree, rate and temperature, as well as the steel chemical composition, was developed. The nature of influence of deformation parameters and the content of chemical elements in steel on its resistance to plastic deformation is scientifically substantiated. Verification of the adequacy of the proposed model by the comparative analysis of the calculated and actual rolling forces during passes in the universal rail-and-structural steel mill JSC “EVRAZ Consolidated West Siberian Metallurgical Plant” (“EVRAZ ZSMK”) showed the possibility of its use for development and improvement of new modes of rails rolling.

  11. A Physical Model of Cosmogenic Nuclide Production in Stony and Iron Meteoroids on the Basis of Simulation Experiments

    NASA Astrophysics Data System (ADS)

    Leya, I.; Lange, H.-J.; Michel, R.; Meltzow, B.; Herpers, U.; Busemann, H.; Wieler, R.; Dittrich-Hannen, B.; Suter, M.; Kubik, P. W.

    1995-09-01

    By extending and improving earlier model calculations [1-4] of cosmogenic nuclide production by GCR particles in extraterrestrial matter, we can now present a physical model without free parameters for a consistent description of GCR production rates in stony and iron meteoroids. The model takes explicitely into account p and n-induced reactions. GCR 4He particles are considered only approximately. It is based on depth-size and bulk-chemistry-dependent spectra of primary and secondary protons and of secondary neutrons calculated by HET and MORSE codes within the HERMES code system [5] and on the cross sections of the underlying reactions. Comprehensive and reliable sets of proton cross sections from thresholds up to 2.6 GeV exist now for many cosmogenic nuclides (see [6] for a review). For n-induced reactions the situation is not so good. Only a few data at low energies and practically no data at higher energies exist. GCR production of cosmogenic nuclides in stony meteoroids is already dominated by neutron-induced reactions for most meteoroid radii. In iron meteoroids neutrons are even more important because of the high mass numbers of the bulk and of consequently higher multiplicities for production of secondary neutrons. In order to overcome this problem, the necessary excitation functions of neutron-induced reactions were determined from experimental thick-target production rates by least-squares unfolding procedures using the code STAYS'L [7]. The data were produced in laboratory experiments under completely controlled conditions [8-11]. The unfolding procedure starts from guess functions (from threshold up to 900 MeV) based on all available experimental neutron cross sections and on theoretical ones calculated by the AREL [12] code which is a relativistic version of the hybrid model of pre-equilibrium reactions [13]. With the new neutron cross sections it is possible to describe simultanously all data from the simulation experiments with an accuracy of better

  12. Cosmogenic nuclides application on French Mediterranean shore platform development

    NASA Astrophysics Data System (ADS)

    Giuliano, Jérémy; Lebourg, Thomas; Godard, Vincent; Dewez, Thomas; Braucher, Régis; Bourlès, Didier; Marçot, Nathalie

    2014-05-01

    Rocky shorelines are among the most common elements of the world's littoral zone, and the potential effects of rising sea level on the ever increasing populations require a better understanding of their dynamics. The sinuosity and heterogeneity of the shoreline morphology at large and intermediate wavelengths (1-100 km) results from their constant evolution under the combined influence of marine and continental forcings. This macro-scale organization is the expression of the action of elementary erosion processes acting at shorter wavelengths (<1 km) which lead to the development of shore platforms by landward retreat of cliff edges. Modern analytical techniques (laser-scaning, micro-erosion meters, aerial surveys) constitute appropriate methods to identify and quantify processes of cliff retreat to 1-100 yrs time-scales. But over this time frame, shore platform development appears imperceptible. Precise knowledge of long-term erosion rates are needed to understand rocky shore evolution, and develop quantitative modeling of platform development. Rocky coasts constitute a Quaternary sea level evolution archive that is partly preserved and progressively destroyed. One major challenges is to determine the degree to which coast morphologies are (i) contemporary, (ii) or ancient features inherited, (iii) or partly inherited from Quaternary interglacial stages. In order to fill the lack of long term coast morphodynamic data, we use cosmogenic nuclides (36Cl) to study abrasion surfaces carved in carbonates lithologies along the French Mediterranean coast, in a microtidal environment (Côte Bleue, West of Marseille). 36Cl concentration heritage influences strongly our interpretations in terms of age and denudation of the surfaces. We propose to constrain heritage in sampling oldest relic marine surfaces at 10m of altitude, and along recent cliff scarp. 36Cl concentrations show that the lowest platforms near sea level are contemporary and the highest ones (8-14 m above sea

  13. Carbon Isotope Composition of Ecosystem Respired Carbon Dioxide in Three Boreal Forest Ecosystems: Measurements and Model Calculations

    NASA Astrophysics Data System (ADS)

    Cai, T.; Flanagan, L. B.

    2007-12-01

    We conducted measurements of seasonal and inter-annual variation in the carbon isotope composition of ecosystem respired CO2 (δR) in aspen, black spruce and jack pine dominated ecosystems in northern Saskatchewan during 2004-2006 as part of the Fluxnet-Canada Research Network. All three sites showed relatively small variation (approximately -26 to -29 per mil) in δR values during the entire study. The measurements were strongly correlated with modeled δ13C values of ecosystem respired CO2. The model calculated leaf CO2 assimilation, stomatal conductance and chloroplast CO2 concentration separately for sunlit and shaded leaves within multiple canopy layers, and, therefore, allowed us to estimate canopy photosynthetic 13C discrimination. All three sites showed variation in canopy 13C discrimination in response to environmental conditions in a manner consistent with well-known leaf-level studies. Specifically, 13C discrimination was positively correlated with soil moisture and negatively correlated with photon flux density, air temperature and vapor pressure deficit. As a consequence a strong diurnal pattern was observed for 13C discrimination. The measured δR values also varied in response to environmental conditions in a manner consistent with well-known leaf-level studies of photosynthetic 13C discrimination, but with a dampened response caused by the contribution of heterotrophic respiration, which had a constant δ13C value. These results indicate that the stable isotope composition of respired CO2 is a useful ecosystem-scale tool to study constraints to photosynthesis and acclimation of ecosystems to environmental stress.

  14. Facies composition calculated from the sonic, neutron, and density log suite, upper part of the Minnelusa Formation, Powder River basin, Wyoming

    USGS Publications Warehouse

    Schmoker, J.W.; Schenk, C.J.

    1988-01-01

    Sandstones and dolomites of the Permian upper part of the Minnelusa Formation are treated here as four-component systems consisting of fluid-filled pore space, quartz, dolomite, and anhydrite. Response equations of sonic, neutron, and density logs form a system of four simultaneous equations. With four equations and four unknowns, the composition of upper Minnelusa facies is defined by the three-log suite and can be calculated by solving a 4 ?? 4 matrix. Such calculations of facies composition help in establishing subsurface correlations and yield information on the diagenesis and physical character of upper Minnelusa sandstones and dolomites. Applications of composition calculations are illustrated by examples drawn from the area of the West Mellott field (T52N, R68W), where the upper Minnelusa is at depths of about 7000 ft (2100m). -from Authors

  15. Simulation of the production rates of cosmogenic nuclides on the Moon based on Geant4

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zhang, Xiaoping; Dong, Wudong; Ren, Zhongzhou; Dong, Tiekuang; Xu, Aoao

    2017-02-01

    A numerical simulation model is built to simulate the production of cosmogenic nuclides based on Geant4 (GEometry ANd Tracking). Some modifications have been made for cross sections in Geant4 using the experimental data or the other proper model and the contributions of all secondary particles caused by cosmic rays are included in our simulation model. Our simulation results suggest a substantial contribution of the secondary charged pions to the production rates of 10Be and 14C, as high as 21.04% for 10Be and 21.36% for 14C, respectively. Within one set of self-consistent parameters, the simulation results of the production rates of the cosmogenic nuclides, 53Mn, 36Cl, 41Ca, 26Al, 10Be, and 14C, agree well with the measured data from Apollo 15 drill core. This model provides users a validated approach to study the production of cosmogenic nuclides on the planet surface and in the meteorites.

  16. Neogene basin infilling from cosmogenic nuclides (10Be and 21Ne) in Atacama, Chile

    NASA Astrophysics Data System (ADS)

    Sanchez, Caroline; Regard, Vincent; Carretier, Sébastien; Riquelme, Rodrigo; Blard, Pierre-Henri; Campos, Eduardo; Brichau, Stéphanie; Lupker, Marteen; Hérail, Gérard

    2017-04-01

    In the hyperarid Atacama Desert, northern Chile, Neogene sediments host copper rich layers (exotic supergene mineralization). Current mines are excavated into relatively thin (<200-300 m) Neogene basins whose infilling chronology is poorly constrained. We took advantage of one of these mining pits, and sampled for 10Be and 21Ne cosmogenic nuclide dosing. These cosmogenic nuclides help constraining the infilling chronology. Indeed, basin sediments were deposited with a cosmogenic nuclide content acquired on hillslopes. Then within the basin, cosmogenic nuclide concentrations evolved through the competing production (quickly decreasing with depth) and disintegration (not for 21Ne). Sampling depths are at ˜100 m and at ˜50 m below the desert surface. First, 21Ne gives lower boundaries for upstream erosion rates or local sedimentation rate. These bounds are between 2 and 10 m/Ma, which is quite important for the area. The ratio between the two cosmogenic nuclides indicate a maximum burial age of 12 Ma (minimal erosion rate of 15 m/Ma) and is surprisingly similar from bottom to top, indicating a probable rapid infilling. We finally processed a Monte-Carlo inversion. This inversion helps taking into account the post-deposition muonic production of cosmogenic nuclides. Inversion results is dependent on the muonic production scheme. Interestingly, the similarity in concentrations from bottom to top pleads for quite low production at depth. Our data finally indicates a quick infilling between 12.5 and 10 Ma BP accounting for ˜100 m of deposition (minimum sedimentation rate of 40 m/Ma).

  17. A study of separation and solidification of group II nuclides in waste salt delivered from the pyrochemical process of used nuclear fuel

    NASA Astrophysics Data System (ADS)

    Eun, H. C.; Choi, J. H.; Kim, N. Y.; Lee, T. K.; Han, S. Y.; Jang, S. A.; Kim, T. J.; Park, H. S.; Ahn, D. H.

    2017-08-01

    If group II nuclides, which contain high heat-generative elements, in waste salt are fabricated into a waste form rich in group II nuclides, the waste form can be used in radionuclide thermoelectric generator applications. For this reason, the separation of group II nuclides in salt (LiCl, LiCl-KCl) was conducted, after which a waste form rich in them was fabricated. In this study, group II nuclide chlorides in salt were effectively separated into a carbonate or oxychloride form, and the separated nuclides were successfully fabricated into a homogenous and stable glass waste form with high contents (45-50 wt%) of these nuclides.

  18. Constraining Landscape History and Glacial Erosivity Using Paired Cosmogenic Nuclides in Upernavik, Northwest Greenland

    NASA Technical Reports Server (NTRS)

    Corbett, Lee B.; Bierman, Paul R.; Graly, Joseph A.; Neumann, Thomas A.; Rood, Dylan H.

    2013-01-01

    High-latitude landscape evolution processes have the potential to preserve old, relict surfaces through burial by cold-based, nonerosive glacial ice. To investigate landscape history and age in the high Arctic, we analyzed in situ cosmogenic Be(sup 10) and Al (sup 26) in 33 rocks from Upernavik, northwest Greenland. We sampled adjacent bedrock-boulder pairs along a 100 km transect at elevations up to 1000 m above sea level. Bedrock samples gave significantly older apparent exposure ages than corresponding boulder samples, and minimum limiting ages increased with elevation. Two-isotope calculations Al(sup26)/B(sup 10) on 20 of the 33 samples yielded minimum limiting exposure durations up to 112 k.y., minimum limiting burial durations up to 900 k.y., and minimum limiting total histories up to 990 k.y. The prevalence of BE(sup 10) and Al(sup 26) inherited from previous periods of exposure, especially in bedrock samples at high elevation, indicates that these areas record long and complex surface exposure histories, including significant periods of burial with little subglacial erosion. The long total histories suggest that these high elevation surfaces were largely preserved beneath cold-based, nonerosive ice or snowfields for at least the latter half of the Quaternary. Because of high concentrations of inherited nuclides, only the six youngest boulder samples appear to record the timing of ice retreat. These six samples suggest deglaciation of the Upernavik coast at 11.3 +/- 0.5 ka (average +/- 1 standard deviation). There is no difference in deglaciation age along the 100 km sample transect, indicating that the ice-marginal position retreated rapidly at rates of approx.120 m yr(sup-1).

  19. Feasibility study for transuranic nuclide measurement on long-length contaminated equipment using neutron detection

    SciTech Connect

    Stromswold, D.C.; Peurrung, A.J.; Arthur, R.J.

    1995-10-01

    The feasibility of measuring the transuranic (TRU) nuclide content of equipment removed from Hanford`s high-level radioactive-waste tanks has been established for components heavier than about 30 kg/m (20 lbs/ft). This conclusion has been reached based on experience with the TRU assay of waste burial boxes, planned improvements to the assay equipment design and assay methodology, and experimental investigation of neutron detector performance in high gamma-ray fields. The experiments indicate that the neutron detectors presently used with Pacific Northwest Laboratory`s box scanner perform correctly in gamma-ray exposure rates of at least 3 R/h. The design of equipment proposed for measuring TRU content incorporates multiple, BF{sub 3}-gas-filled neutron counters in a configuration that is approximately 0.5 m wide and 2 m long, with polyethylene to moderate high-energy neutrons down to thermal energy. Specially developed electrical systems are used to eliminate response to gamma-rays. Performance of the assay would require 10 to 14 hours of time during which close-range access is provided to the waste and its burial container. A standard neutron source, will be placed within the burial container (before inserting components) to allow calibration of the detector. Final calculation of the TRU contamination will utilize plausible conservative assumptions concerning the spatial, isotopic, and elemental distributions of any TRU present. For long-length equipment, the detector array collects data at various positions along the length of the equipment. Separate monitoring of the cosmic-ray-induced neutron background during the assay period will provide confidence that observed changes in counts at the equipment are not related to changing background. Background measurements using the burial container and equipment {open_quotes}skid{close_quotes} will allow compensation for neutrons that are created by cosmic-ray spallation within the burial container.

  20. Applications of in situ cosmogenic nuclides in the geologic site characterization of Yucca Mountain, Nevada

    SciTech Connect

    Gosse, J.C.; Harrington, C.D.; Whitney, J.W.

    1995-12-31

    The gradual buildup of rare isotopes from interactions between cosmic rays and atoms in an exposed rock provides a new method of directly determining the exposure age of rock surfaces. The cosmogenic nuclide method can also provide constraints on erosion rates and the length of time surface exposure was interrupted by burial. Numerous successful applications of the technique have been imperative to the complete surface geologic characterization of Yucca Mountain, Nevada, a potential high level nuclear waste repository. In this short paper, we summarize the cosmogenic nuclide method and describe with examples some the utility of the technique in geologic site characterization. We report preliminary results from our ongoing work at Yucca Mountain.

  1. Apparatus and method for quantitatively evaluating total fissile and total fertile nuclide content in samples

    DOEpatents

    Caldwell, John T.; Kunz, Walter E.; Cates, Michael R.; Franks, Larry A.

    1985-01-01

    Simultaneous photon and neutron interrogation of samples for the quantitative determination of total fissile nuclide and total fertile nuclide material present is made possible by the use of an electron accelerator. Prompt and delayed neutrons produced from resulting induced fissions are counted using a single detection system and allow the resolution of the contributions from each interrogating flux leading in turn to the quantitative determination sought. Detection limits for .sup.239 Pu are estimated to be about 3 mg using prompt fission neutrons and about 6 mg using delayed neutrons.

  2. Reprocessing system with nuclide separation based on chromatography in hydrochloric acid solution

    SciTech Connect

    Suzuki, Tatsuya; Tachibana, Yu; Koyama, Shi-ichi

    2013-07-01

    We have proposed the reprocessing system with nuclide separation processes based on the chromatographic technique in the hydrochloric acid solution system. Our proposed system consists of the dissolution process, the reprocessing process, the minor actinide separation process, and nuclide separation processes. In the reprocessing and separation processes, the pyridine resin is used as a main separation media. It was confirmed that the dissolution in the hydrochloric acid solution is easily achieved by the plasma voloxidation and by the addition of oxygen peroxide into the hydrochloric acid solution.

  3. Advanced short-lived nuclide NAA with application in the life sciences.

    PubMed

    Papadopoulos, N N; Tsagas, N F

    1994-01-01

    A new technique for short-lived nuclide activation analysis has been developed that compensates the rapid radioactive decay during the counting period by simultaneous approach of the sample holder to the detector with a mechanical device, permitting prolongation of the counting time and reduction of the required complementary cyclic activation to avoid sample container damage. The operation of the analytical system is automated by a programmable logic controller (PLC). This improvement of short-lived nuclide activation analysis, providing a high throughput, is important in biological and environmental research, where often a large number of samples has to be analyzed for sufficient sampling statistics.

  4. Using U/Th Series Nuclide Systematics for Modelling Subsurface Radionuclide Transport

    NASA Astrophysics Data System (ADS)

    Porcelli, D.; Strekopytov, S.; Shaw, S.; Hilton, D.

    2007-05-01

    U- and Th- series nuclides have provided essential tools for studying weathering and subsurface element transport processes. The radionuclides U, Th, Ra, Rn, and Pb have a range of half-lives and contrasting chemical behaviours, and their distribution between subsurface solids and water can be used to quantify rates of soil formation, chemical and mechanical weathering of watersheds, and potentially, subsurface water flow rates. Decay systematics clearly connect the different isotopes, although transfer between different phases and through subsurface systems are generally defined through a series of assumptions that have not been experimentally substantiated. Modification of these assumptions may have significant effects on the choice of models and the conclusions of U/Th series studies. Two key areas of uncertainty are: Nuclide inputs. Comparing the different isotopes requires relating the input rates from recoil and weathering. The common assumption is that nuclides are released at similar rates by recoil and congruently by weathering. Various theories have been proposed for preferential release of Rn and leaching of radionuclides, although such effects, as well as possible radionuclide fractionation during weathering release, have not been substantiated. Surface interaction mechanisms. It is generally assumed that radionuclides are removed from water onto surfaces only by reversible adsorption. However, coprecipitation, incorporation into aging secondary mineral structures, and different binding mechanisms can inhibit isotope exchange with nuclides in solution. Data from the unconfined Mojave River Basin aquifer, with a reasonably well-defined flow pattern and groundwater ages of up to ~40,000 years illustrates the response of the U/Th series nuclides to extended water- rock interaction. Measurements of 222Rn find relatively uniform recoil rates throughout the aquifer. If this rate is applied to other daughter nuclides, then the rate of 234Th release can be

  5. 26Al - 10Be cosmogenic nuclide isochron burial dating in combination with luminescence dating of two Danube terraces

    NASA Astrophysics Data System (ADS)

    Neuhuber, Stephanie; Braumann, Sandra; Lüthgens, Christopher; Fiebig, Markus; Häuselmann, Philipp; Schäfer, Jörg

    2016-04-01

    The Quaternary sediment record in the Vienna Basin is influenced by two main factors: (1) the tectonic development of a pull apart basin along a sinistral strike slip fault system between the Eastern Alps and the West Carpathians and by (2) strongly varying sediment supply during the Plio- and Pleistocene. From the Late Pannonian (8.8 Ma) onward a large-scale regional uplift (Decker et al., 2005) controls terrace formation in the Vienna Basin. The main sediment supply into the Vienna Basin originates from the Danube, and subordinately from tributaries to the south such as Piesting, Fischa, Leitha and from the north by the river March. Today the Danube forms a large floodplain that is bordered to the north by one large Pleistocene terrace, the Gänserndorf Terrace that is situated 17 m above todays water level. Farther to the east a smaller terrace, the Schlosshof Terrace, reaches 25 m above todays water level. These terrace levels are tilted by movement of underlying blocks (Peresson, 2006). Both, the Schlosshof and Gänserndorf terraces consist of successions of up to 2 m thick gravel beds with intercalated sand layers or -lenses that may locally reach thicknesses up to 0.8 m. At each terrace one gavel pit was selected to calculate the time of terrace deposition by luminescence dating in combination with 26Al/10Be cosmogenic nuclide isochrone dating (Balco and Rovery, 2008). Five quartz stones from the base of each terrace were physically and chemically processed to obtain Al and Be oxides for Acceleration Mass Spectrometry. Sand samples for luminescence dating were taken above the cosmogenic nuclide samples from the closest suitable sand body. Decker et al., 2005. QSR 24, 307-322 Peresson, 2006 Geologie der österreichischen Bundesländer Niederösterreich 255-258 Balco and Rovey, 2008. AJS 908, 1083-1114 Thanks to FWF P 23138-N19, OMAA 90öu17

  6. A New Approach for the Determination of Dose Rate and Radioactivity for Detected Gamma Nuclides Using an Environmental Radiation Monitor Based on an NaI(Tl) Detector.

    PubMed

    Ji, Young-Yong; Kim, Chang-Jong; Lim, Kyo-Sun; Lee, Wanno; Chang, Hyon-Sock; Chung, Kun Ho

    2017-10-01

    To expand the application of dose rate spectroscopy to the environment, the method using an environmental radiation monitor (ERM) based on a 3' × 3' NaI(Tl) detector was used to perform real-time monitoring of the dose rate and radioactivity for detected gamma nuclides in the ground around an ERM. Full-energy absorption peaks in the energy spectrum for dose rate were first identified to calculate the individual dose rates of Bi, Ac, Tl, and K distributed in the ground through interference correction because of the finite energy resolution of the NaI(Tl) detector used in an ERM. The radioactivity of the four natural radionuclides was then calculated from the in situ calibration factor-that is, the dose rate per unit curie-of the used ERM for the geometry of the ground in infinite half-space, which was theoretically estimated by Monte Carlo simulation. By an intercomparison using a portable HPGe and samples taken from the ground around an ERM, this method to calculate the dose rate and radioactivity of four nuclides using an ERM was experimentally verified and finally applied to remotely monitor them in real-time in the area in which the ERM had been installed.

  7. Production and Separation of T = 1/2 Nuclides for {beta}--{nu} angular correlation measurements

    SciTech Connect

    Delahaye, P.; Bajeat, O.; Saint Laurent, M. G.; Thomas, J. C.; Traykov, E.; Lienard, E.; Ban, G.; Durand, D.; Flechard, X.; Naviliat-Cuncic, O.; Stora, T.; Collaboration: GANISOL Group

    2011-11-30

    The SPIRAL facility at GANIL, which uses the so-called ISOL method to produce radioactive ion beams, is being upgraded to extend its production capabilities to the metallic beams of neutron deficient isotopes. We discuss here the potentialities offered by this upgrade for the measurement of the {beta}--{nu} angular correlation in the {beta}--decay of mirror nuclides.

  8. The isotopic composition of iron-group galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, M. E.; Leske, R. A.

    1995-01-01

    Results from studies of the isotopic composition of iron group elements in the galactic cosmic radiation are reviewed, emphasizing recently reported measurements from the ISEE-3 spacecraft. The observed isotope distributions for the elements Ti through Mn are in good agreement with those expected for a propagated solar-like source composition, with the possible exception of an enhanced abundance of Ti-50. It is found that a significant fraction of the radioactive secondary nuclide Mn-54 has decayed, indicating a confinement time of iron group cosmic rays in the galaxy of at least 2 Myr. The source ratio Fe-54/Fe-56 is found to be consistent with the solar value, but the ratio Ni-60/Ni-58 is greater than solar by a factor of 2.8+/-1.0. The measured abundance of Co-59 is significantly greater than the calculated secondary contribution, suggesting that this nuclide has been produced in the source regions by the electron capture decay of Ni-59 and implying a time delay between nucleosynthesis and acceleration approximately greater than 10(exp 5) yr.

  9. Mass Determination of Two-Proton Radioactive Nuclides

    SciTech Connect

    Miernik, Krzysztof A

    2012-01-01

    The masses of heavy two-proton emitters (45Fe, 48Ni and 54Zn) are calculated, basing on experimentally measured two-proton decay energies. The results are compared with theoretical predictions and extrapolations.

  10. Kinetics analysis and quantitative calculations for the successive radioactive decay process

    NASA Astrophysics Data System (ADS)

    Zhou, Zhiping; Yan, Deyue; Zhao, Yuliang; Chai, Zhifang

    2015-01-01

    The general radioactive decay kinetics equations with branching were developed and the analytical solutions were derived by Laplace transform method. The time dependence of all the nuclide concentrations can be easily obtained by applying the equations to any known radioactive decay series. Taking the example of thorium radioactive decay series, the concentration evolution over time of various nuclide members in the family has been given by the quantitative numerical calculations with a computer. The method can be applied to the quantitative prediction and analysis for the daughter nuclides in the successive decay with branching of the complicated radioactive processes, such as the natural radioactive decay series, nuclear reactor, nuclear waste disposal, nuclear spallation, synthesis and identification of superheavy nuclides, radioactive ion beam physics and chemistry, etc.

  11. A MATLAB toolbox and Excel workbook for calculating the densities, seismic wave speeds, and major element composition of minerals and rocks at pressure and temperature

    NASA Astrophysics Data System (ADS)

    Abers, Geoffrey A.; Hacker, Bradley R.

    2016-02-01

    To interpret seismic images, rock seismic velocities need to be calculated at elevated pressure and temperature for arbitrary compositions. This technical report describes an algorithm, software, and data to make such calculations from the physical properties of minerals. It updates a previous compilation and Excel® spreadsheet and includes new MATLAB® tools for the calculations. The database of 60 mineral end-members includes all parameters needed to estimate density and elastic moduli for many crustal and mantle rocks at conditions relevant to the upper few hundreds of kilometers of Earth. The behavior of α and β quartz is treated as a special case, owing to its unusual Poisson's ratio and thermal expansion that vary rapidly near the α-β transition. The MATLAB tools allow integration of these calculations into a variety of modeling and data analysis projects.

  12. The effect of cross-section uncertainties on the derivation of source abundances from cosmic-ray composition observations

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, M. E.

    1983-01-01

    It is pointed out that the derivation of source abundances from the composition observed near the earth requires that the secondary contribution to the observed nuclidic abundances be calculated from a model of cosmic-ray propagation. A crucial element in such a calculation is the choice of nuclear fragmentation cross sections. Uncertainties in these cross sections give rise to uncertainties in the derived source abundances. It is shown here that the uncertainties in fragmentation cross sections can, in certain important cases, contribute significantly to the uncertainties in cosmic ray source abundances deduced from the observed composition. For this reason, it is essential that reliable estimates of the effect of cross section uncertainties be made when interpreting the source composition deduced from cosmic ray observations. In addition, formulas are presented which can be used to obtain such estimates with a minimum of computational effort.

  13. The Light Curve of SN 1987A Revisited: Constraining Production Masses of Radioactive Nuclides

    NASA Astrophysics Data System (ADS)

    Seitenzahl, Ivo R.; Timmes, F. X.; Magkotsios, Georgios

    2014-09-01

    We revisit the evidence for the contribution of the long-lived radioactive nuclides 44Ti, 55Fe, 56Co, 57Co, and 60Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we obtain an approximate bolometric light curve out to 4334 days by scaling the late time V-band data by a constant factor where no bolometric light curve data is available. Considering the five most relevant decay chains starting at 44Ti, 55Co, 56Ni, 57Ni, and 60Co, we perform a least squares fit to the constructed composite bolometric light curve. For the nickel isotopes, we obtain best fit values of M(56Ni) = (7.1 ± 0.3) × 10-2 M ⊙ and M(57Ni) = (4.1 ± 1.8) × 10-3 M ⊙. Our best fit 44Ti mass is M(44Ti) = (0.55 ± 0.17) × 10-4 M ⊙, which is in disagreement with the much higher (3.1 ± 0.8) × 10-4 M ⊙ recently derived from INTEGRAL observations. The associated uncertainties far exceed the best fit values for 55Co and 60Co and, as a result, we only give upper limits on the production masses of M(55Co) < 7.2 × 10-3 M ⊙ and M(60Co) < 1.7 × 10-4 M ⊙. Furthermore, we find that the leptonic channels in the decay of 57Co (internal conversion and Auger electrons) are a significant contribution and constitute up to 15.5% of the total luminosity. Consideration of the kinetic energy of these electrons is essential in lowering our best fit nickel isotope production ratio to [57Ni/56Ni] = 2.5 ± 1.1, which is still somewhat high but is in agreement with gamma-ray observations and model predictions.

  14. The light curve of SN 1987A revisited: constraining production masses of radioactive nuclides

    SciTech Connect

    Seitenzahl, Ivo R.; Timmes, F. X.; Magkotsios, Georgios

    2014-09-01

    We revisit the evidence for the contribution of the long-lived radioactive nuclides {sup 44}Ti, {sup 55}Fe, {sup 56}Co, {sup 57}Co, and {sup 60}Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we obtain an approximate bolometric light curve out to 4334 days by scaling the late time V-band data by a constant factor where no bolometric light curve data is available. Considering the five most relevant decay chains starting at {sup 44}Ti, {sup 55}Co, {sup 56}Ni, {sup 57}Ni, and {sup 60}Co, we perform a least squares fit to the constructed composite bolometric light curve. For the nickel isotopes, we obtain best fit values of M({sup 56}Ni) = (7.1 ± 0.3) × 10{sup –2} M {sub ☉} and M({sup 57}Ni) = (4.1 ± 1.8) × 10{sup –3} M {sub ☉}. Our best fit {sup 44}Ti mass is M({sup 44}Ti) = (0.55 ± 0.17) × 10{sup –4} M {sub ☉}, which is in disagreement with the much higher (3.1 ± 0.8) × 10{sup –4} M {sub ☉} recently derived from INTEGRAL observations. The associated uncertainties far exceed the best fit values for {sup 55}Co and {sup 60}Co and, as a result, we only give upper limits on the production masses of M({sup 55}Co) < 7.2 × 10{sup –3} M {sub ☉} and M({sup 60}Co) < 1.7 × 10{sup –4} M {sub ☉}. Furthermore, we find that the leptonic channels in the decay of {sup 57}Co (internal conversion and Auger electrons) are a significant contribution and constitute up to 15.5% of the total luminosity. Consideration of the kinetic energy of these electrons is essential in lowering our best fit nickel isotope production ratio to [{sup 57}Ni/{sup 56}Ni] = 2.5 ± 1.1, which is still somewhat high but is in agreement with gamma-ray observations and model predictions.

  15. An improved choice of oscillator basis for banana shaped nuclides

    SciTech Connect

    Chasman, R.R.

    1994-03-01

    The question of the appropriate choice of oscillator basis functions for studying exotic nuclear shapes is raised. Difficulties with the conventional choice of oscillator basis states are noted for shapes having a large banana component. A prescription for an improved oscillator basis to study these shapes is given. It can be applied in a more general context. New calculations with this improved basis are presented for the banana deformation mode. The change of basis gives results that improve the prospects of finding states in the banana minimum for many isotopes of Tl, Pb and Bi.

  16. Optical model methods of predicting nuclide production from spallation reactions.

    PubMed

    Ramsey, C R; Townsend, L W; Tripathi, R K; Cucinotta, F A

    1998-02-01

    Quantum mechanical optical model methods for calculating isotope production cross sections from the spallation of heavy nuclei by high-energy protons are developed from a modified abrasion-ablation collision formalism. The abrasion step is treated quantum-mechanically as a knockout process which leaves the residual prefragment nucleus in an excited state. In ablation the prefragment deexcites to produce the final fragment. The excitation energies of the prefragments are estimated from a combination of liquid drop and frictional-spectator interaction considerations. Estimates of elemental and isotopic production cross sections are in good agreement with recently published cross section measurements.

  17. ANEMOS: A computer code to estimate air concentrations and ground deposition rates for atmospheric nuclides emitted from multiple operating sources

    SciTech Connect

    Miller, C.W.; Sjoreen, A.L.; Begovich, C.L.; Hermann, O.W.

    1986-11-01

    This code estimates concentrations in air and ground deposition rates for Atmospheric Nuclides Emitted from Multiple Operating Sources. ANEMOS is one component of an integrated Computerized Radiological Risk Investigation System (CRRIS) developed for the US Environmental Protection Agency (EPA) for use in performing radiological assessments and in developing radiation standards. The concentrations and deposition rates calculated by ANEMOS are used in subsequent portions of the CRRIS for estimating doses and risks to man. The calculations made in ANEMOS are based on the use of a straight-line Gaussian plume atmospheric dispersion model with both dry and wet deposition parameter options. The code will accommodate a ground-level or elevated point and area source or windblown source. Adjustments may be made during the calculations for surface roughness, building wake effects, terrain height, wind speed at the height of release, the variation in plume rise as a function of downwind distance, and the in-growth and decay of daughter products in the plume as it travels downwind. ANEMOS can also accommodate multiple particle sizes and clearance classes, and it may be used to calculate the dose from a finite plume of gamma-ray-emitting radionuclides passing overhead. The output of this code is presented for 16 sectors of a circular grid. ANEMOS can calculate both the sector-average concentrations and deposition rates at a given set of downwind distances in each sector and the average of these quantities over an area within each sector bounded by two successive downwind distances. ANEMOS is designed to be used primarily for continuous, long-term radionuclide releases. This report describes the models used in the code, their computer implementation, the uncertainty associated with their use, and the use of ANEMOS in conjunction with other codes in the CRRIS. A listing of the code is included in Appendix C.

  18. Calculation of 2-temperature plasma thermo-physical properties considering condensed phases: application to CO2-CH4 plasma: part 1. Composition and thermodynamic properties

    NASA Astrophysics Data System (ADS)

    Wu, Yi; Chen, Zhexin; Rong, Mingzhe; Cressault, Yann; Yang, Fei; Niu, Chunping; Sun, Hao

    2016-10-01

    As the first part of this series of papers, a new calculation method for composition and thermodynamic properties of 2-temperature plasma considering condensed species under local chemical equilibrium (LCE) and local phase equilibrium assumption is presented. The 2-T mass action law and chemical potential are used to determine the composition of multiphase system. The thermo-physical properties of CO2-CH4 mixture, which may be a possible substitution for SF6, are calculated by this method as an example. The influence of condensed graphite, non-LTE effect, mixture ratio and pressure on the thermo-physical properties has been discussed. The results will serve as reliable reference data for computational simulation of CO2-CH4 plasmas.

  19. Nuclide Importance to Criticality Safety, Decay Heating, and Source Terms Related to Transport and Interim Storage of High-Burnup LWR Fuel

    SciTech Connect

    Gauld, I. C.; Ryman, J. C.

    2000-12-11

    This report investigates trends in the radiological decay properties and changes in relative nuclide importance associated with increasing enrichments and burnup for spent LWR fuel as they affect the areas of criticality safety, thermal analysis (decay heat), and shielding analysis of spent fuel transport and storage casks. To facilitate identifying the changes in the spent fuel compositions that most directly impact these application areas, the dominant nuclides in each area have been identified and ranked by importance. The importance is investigated as a function of increasing burnup to assist in identifying the key changes in spent fuel characteristics between conventional- and extended-burnup regimes. Studies involving both pressurized water-reactor (PWR) fuel assemblies and boiling-water-reactor (BWR) assemblies are included. This study is seen to be a necessary first step in identifying the high-burnup spent fuel characteristics that may adversely affect the accuracy of current computational methods and data, assess the potential impact on previous guidance on isotopic source terms and decay-heat values, and thus help identify areas for methods and data improvement. Finally, several recommendations on the direction of possible future code validation efforts for high-burnup spent fuel predictions are presented.

  20. Analysis of nuclide transport under natural convection and time dependent boundary condition using TOUGH2

    SciTech Connect

    Javeri, V.

    1995-03-01

    After implementation of TOUGH2 at GRS in summer 91, it was first used to analyse the gas transport in a repository for the nuclear waste with negligible heat generation and to verify the results obtained with ECLIPSE/JAV 92/. Since the original version of TOUGH2 does not directly simulate the decay of radionuclide and the time dependent boundary conditions, it is not a appropriate tool to study the nuclide transport in a porous medium/PRU 87, PRU 91/. Hence, in this paper some modifications are proposed to study the nuclide transport under combined influence of natural convection diffusion, dispersion and time dependent boundary condition. Here, a single phase fluid with two liquid components is considered as in equation of state model for water and brine/PRU 91A/.

  1. The exposure history of Jilin and production rates of cosmogenic nuclides

    NASA Technical Reports Server (NTRS)

    Heusser, G.

    1986-01-01

    Jilin, the largest known story meteorite, is a very suitable object for studying the systematics of cosmic ray produced nuclides in stony meteorites. Its well established two stage exposure history even permits to gain information about two different irradiation geometries (2pi and 4pi). All stable and long-lived cosmogenic nuclides measured in Jilin so far correlate well with each other. An example is shown where the Al-26 activities are plotted vs. the spallogenic Ne-21 concentration. These records of cosmic-ray interaction in Jilin can be used both to determine the history of the target and to study the nature of production rate profiles. This is unavoidably a bootstrap process, involving studying one with assumption about the other. Production rate equations are presented and discussed.

  2. The exposure history of Jilin and production rates of cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    Heusser, G.

    Jilin, the largest known story meteorite, is a very suitable object for studying the systematics of cosmic ray produced nuclides in stony meteorites. Its well established two stage exposure history even permits to gain information about two different irradiation geometries (2pi and 4pi). All stable and long-lived cosmogenic nuclides measured in Jilin so far correlate well with each other. An example is shown where the Al-26 activities are plotted vs. the spallogenic Ne-21 concentration. These records of cosmic-ray interaction in Jilin can be used both to determine the history of the target and to study the nature of production rate profiles. This is unavoidably a bootstrap process, involving studying one with assumption about the other. Production rate equations are presented and discussed.

  3. Studies on cosmogenic nuclides in meteorites with regard to an application as potential depth indicators

    NASA Technical Reports Server (NTRS)

    Sarafin, R.; Herpers, U.; Englert, P.; Wieler, R.; Signer, P.; Bonani, G.; Hofmann, H. J.; Morenzoni, E.; Nessi, M.; Suter, M.

    1986-01-01

    Measurements of stable and radioactive spallation products in meteorites allow to investigate their histories, especially with respect to the exposure to galactic cosmic ray particles and the pre-atmospheric size of the object. While the concentrations of spallation products lead to the determination of exposure and terrestrial ages, production rate ratios are characteristic for the location of the sample in the meteorite. So, one of the aims of this investigation on meteorites is to obtain depth indicators from suitable pairs of cosmogenic nuclides. Because of the different depth profiles for nuclide productions it is necessary to determine the concentrations of a larger number of spallation products in aliquots of a single small sample. Such same sample measurements of Be-10 and light noble gases were performed on 15 ordinary chondrites (7 H- and 8 L-chondrites. Be-10 was determined by accelerator mass spectrometry and the noble gases were measured by static mass spectrometry. The results are summarized and discussed.

  4. Determination of Concentrations of Radioactive Nuclides in Soil Samples using Gamma Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Adil, Arsalan; Weaver, Joshua

    2015-10-01

    A hyper-pure Germanium detector system was used to determine the contents and concentrations of various nuclides in soil samples collected from different parts of the United States. These include areas in close proximity to nuclear power plants, areas susceptible to nuclear fallout from weapons testing from the pre Comprehensive Nuclear Test Ban Treaty (CTBT) period, and areas vulnerable to fallout from Fukushima from the west coast. The concentrations of naturally occurring nuclides in the 238U, 232Th, and 40K decay chains as well as that of synthetic isotopes of 137Cs and 60Co were measured with the aid of Genie-2000 and Radware (gf3m). An efficiency curve was obtained by designing a simulation and compared with standard sources. The research, now in its next stage, aims to do the same in samples from Karachi (Pakistan) which is home to three nuclear power plant projects but has no available baseline radioactivity measurements. University of Richmond.

  5. Heavy mass elements total half-lives for selected long-lived nuclides

    SciTech Connect

    Holden, N.E.

    1985-01-01

    In the past, many compilations and evaluations of half-lives have been made which have uncritically accepted authors' values and uncertainties. They have merely recommended weight-averaged reported results. This evaluation attempts to reanalyze each experiment in the literature including an estimate of the standard deviation utilizing, where possible, an estimate of the systematic error. This paper constitutes a preliminary step in the process of recommending values. The long-lived nuclides of heavy mass elements are of interest in determining geological ages using the Re-Os or the Lu-Hf dating methods, in supplying information on the p-process (proton capture) of nucleo-synthesis, in providing information on lepton number conservation and the rest mass for the electron neutrino from double ..beta.. decay processes and in the case of tantalum because it represents the first long-lived state which is actually an isomer. Experimental data on the half-lives of selected nuclides have been evaluated and recommended values and uncertainties are presented for the following nuclides: /sup 128/Te, /sup 130/Te, /sup 129/I, /sup 138/La, /sup 144,145/Nd, /sup 146,147,148/Sm, /sup 152/Gd, /sup 154/Dy, /sup 176/Lu, /sup 174/Hf, /sup 180/Ta, /sup 187/Re, /sup 186/Os, /sup 190/Pt, /sup 204,205/Pb and /sup 230,232/Th. It is shown that /sup 204/Pb, which was previously thought to be radioactive, is stable. For /sup 205/Pb, the L electron capture x-rays have been revised for the M and higher x-ray yields. The resulting half-life for /sup 205/Pb is 1.9 +- 0.3 x 10/sup 7/ years. /sup 146/Sm with a half-life of 1.03 +- 0.05 x 10/sup 8/ years is the longest-lived extinct natural nuclide. 21 tabs.

  6. Fabrication of a set of realistic torso phantoms for calibration of transuranic nuclide lung counting facilities

    SciTech Connect

    Griffith, R.V.; Anderson, A.L.; Sundbeck, C.W.; Alderson, S.W.

    1983-10-26

    A set of 16 tissue equivalent torso phantoms has been fabricated for use by major laboratories involved in counting transuranic nuclides in the lung. These phantoms, which have bone equivalent plastic rib cages, duplicate the performance of the DOE Realistic Phantom set. The new phantoms (and their successors) provide the user laboratories with a highly realistic calibration tool. Moreover, use of these phantoms will allow participating laboratories to intercompare calibration information, both on formal and informal bases. 3 refs., 2 figs.

  7. Total and spontaneous fission half-lives of the americium and curium nuclides

    SciTech Connect

    Holden, N.E.

    1984-01-01

    The total half-life and the half-life for spontaneous fission are evaluated for the various long-lived nuclides of interest. Recommended values are presented for /sup 241/Am, /sup 242m/Am, /sup 243/Am, /sup 242/Cm, /sup 243/Cm, /sup 244/Cm, /sup 245/Cm, /sup 246/Cm, /sup 247/Cm, /sup 248/Cm, and /sup 250/Cm. The uncertainties are provided at the 95% confidence limit for each of the recommended values.

  8. Measuring glacial erosion of bedrock landforms with cosmogenic nuclide depth profiles

    NASA Astrophysics Data System (ADS)

    Ploskey, Z. T.; Stone, J. O.

    2013-12-01

    Erosion by glaciers and ice sheet shapes alpine and continental topography, renews soil cover, and plays a crucial role in the long-term carbon cycle by exposing fresh silicate rock to weathering. Rates of glacial erosion are difficult to quantify directly, and sediment budgets provide only catchment-wide averages. We have developed a method for measuring long-term average subglacial erosion at the outcrop scale, based on inverse analysis of cosmogenic nuclide depth profiles. Cosmogenic nuclide production decreases with depth (markedly so by 2-3 m depth), but persists at low levels to depths of tens to hundreds of meters. Because subglacial erosion removes only the upper part of the nuclide profile, nuclides can accumulate in the deep production zone of the profile over many glacial cycles. Using the Neighorhood Algorithm, we invert depth profile measurements for posterior probability distributions of recent and long term average erosion rates. However, inversion using any method requires putting constraints on the fraction of time that the rock surface has been exposed, and for rapid erosion, low concentrations require difficult measurements. One can not deduce specific erosional history, but it is possible to approximate the erosion rate over the past million years or less. We measured Be-10 in trial profiles from quarry sections on glacially-shaped mountains in Maine. Initial results indicate glacial erosion rates at these sites of 70-80 m/Myr, assuming the surface is ice-covered 15% of the time. We plan to measure two drill cores from a third site, to contrast abrasion rates on the mountain summit with rates of erosion dominated by plucking from lee-side surfaces.

  9. Light nuclides produced in the proton-induced spallation of {sup 238}U at 1 GeV

    SciTech Connect

    Ricciardi, M.V.; Armbruster, P.; Enqvist, T.; Kelic, A.; Rejmund, F.; Schmidt, K.-H.; Yordanov, O.; Benlliure, J.; Pereira, J.; Bernas, M.; Mustapha, B.; Stephan, C.; Tassan-Got, L.

    2006-01-15

    The production of light and intermediate-mass nuclides formed in the reaction {sup 1}H+{sup 238}U at 1 GeV was measured at the Fragment Separator at GSI, Darmstadt. The experiment was performed in inverse kinematics, by shooting a 1 A GeV {sup 238}U beam on a thin liquid-hydrogen target. A total of 254 isotopes of all elements in the range 7{<=}Z{<=}37 were unambiguously identified, and the velocity distributions of the produced nuclides were determined with high precision. The results show that the nuclides are produced in a very asymmetric binary decay of heavy nuclei originating from the spallation of uranium. All the features of the produced nuclides merge with the characteristics of the fission products as their mass increases.

  10. Implementation of Improved Transverse Shear Calculations and Higher Order Laminate Theory Into Strain Rate Dependent Analyses of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Zhu, Lin-Fa; Kim, Soo; Chattopadhyay, Aditi; Goldberg, Robert K.

    2004-01-01

    A numerical procedure has been developed to investigate the nonlinear and strain rate dependent deformation response of polymer matrix composite laminated plates under high strain rate impact loadings. A recently developed strength of materials based micromechanics model, incorporating a set of nonlinear, strain rate dependent constitutive equations for the polymer matrix, is extended to account for the transverse shear effects during impact. Four different assumptions of transverse shear deformation are investigated in order to improve the developed strain rate dependent micromechanics model. The validities of these assumptions are investigated using numerical and theoretical approaches. A method to determine through the thickness strain and transverse Poisson's ratio of the composite is developed. The revised micromechanics model is then implemented into a higher order laminated plate theory which is modified to include the effects of inelastic strains. Parametric studies are conducted to investigate the mechanical response of composite plates under high strain rate loadings. Results show the transverse shear stresses cannot be neglected in the impact problem. A significant level of strain rate dependency and material nonlinearity is found in the deformation response of representative composite specimens.

  11. Mass measurements of the shortest-lived nuclides à la MISTRAL

    NASA Astrophysics Data System (ADS)

    Lunney, D.; Vieira, N.; Audi, G.; Gaulard, C.; de Saint Simon, M.; Thibault, C.

    2006-04-01

    At Princeton in the 1960's, L.G. Smith invented an instrument of astonishing accuracy and rapid measurement time, derived from his so-called mass synchrometer. Using the same principle, a radiofrequency spectrometer was constructed in Orsay to measure masses of the shortest-lived nuclides at Cern's Isolde facility. Smith's spectrometer is now a museum piece, making the Orsay version (since baptized, MISTRAL) the sole example of such an instrument and the only one ever to be used on-line. Here we report on a measurement of the 65[thin space]ms half-life, NDZ nuclide performed with MISTRAL. The measured mass excess of [thin space]keV is compared with that obtained by ISOLTRAP, since independent measurements using different techniques assure a healthy gene pool for the recommended masses of the atomic mass evaluation. The nuclide is the heaviest for which a precise mass is of importance for the so-called Wigner energy. A discussion is presented concerning this Wigner energy, perhaps the last component of nuclear mass formulas resisting microscopic treatment.

  12. Synchrotron radiation based Mössbauer absorption spectroscopy of various nuclides

    NASA Astrophysics Data System (ADS)

    Masuda, Ryo; Kobayashi, Yasuhiro; Kitao, Shinji; Kurokuzu, Masayuki; Saito, Makina; Yoda, Yoshitaka; Mitsui, Takaya; Seto, Makoto

    2016-12-01

    Synchrotron-radiation (SR) based Mössbauer absorption spectroscopy of various nuclides is reviewed. The details of the measuring system and analysis method are described. Especially, the following two advantages of the current system are described: the detection of internal conversion electrons and the close distance between the energy standard scatterer and the detector. Both of these advantages yield the enhancement of the counting rate and reduction of the measuring time. Furthermore, SR-based Mössbauer absorption spectroscopy of 40K, 151Eu, and 174Yb is introduced to show the wide applicability of this method. In addition to these three nuclides, SR-based Mössbauer absorption spectroscopy of 61Ni, 73Ge, 119Sn, 125Te, 127I, 149Sm, and 189Os has been performed. We continue to develop the method to increase available nuclides and to increase its ease of use. The complementary relation between the time-domain method using SR, such as nuclear forward scattering and the energy-domain methods such as SR-based Mössbauer absorption spectroscopy is also noted.

  13. Weathering histories of Chinese loess deposits based on uranium and thorium series nuclides and cosmogenic {sup 10}Be

    SciTech Connect

    Gu, Z.Y. |; Lal, D.; Liu, T.S.

    1997-12-01

    The long, continuous deposition of dust in the Chinese loess plateau offers an unique opportunity to study the nature of soil weathering in a wide range of climatic conditions. In this paper we report on measurements of concentrations of U- and Th-series nuclides and of major cations in 150 loess and paleosol samples from five sites, going back 2.5 Ma. Using the results for {sup 10}Be concentrations in these soils, we determined the absolute amounts of water added to several soil units and obtained: (1) first-order leaching constants for U and several cations and (2) the compositions of the soils contributing to the dust-source regions and of the dust at deposition. Further, based on analyses of {sup 230}Th in soils deposited in the past ca. 140 ka, we determined when the soils weathered in the source regions. We conclude that most of the weathering in the dust-source regions may have occurred during the interglacials. 34 refs., 8 figs., 2 tabs.

  14. The Navy/NASA Engine Program (NNEP89): Interfacing the program for the calculation of complex Chemical Equilibrium Compositions (CEC)

    NASA Technical Reports Server (NTRS)

    Gordon, Sanford

    1991-01-01

    The NNEP is a general computer program for calculating aircraft engine performance. NNEP has been used extensively to calculate the design and off-design (matched) performance of a broad range of turbine engines, ranging from subsonic turboprops to variable cycle engines for supersonic transports. Recently, however, there has been increased interest in applications for which NNEP is not capable of simulating, such as the use of alternate fuels including cryogenic fuels and the inclusion of chemical dissociation effects at high temperatures. To overcome these limitations, NNEP was extended by including a general chemical equilibrium method. This permits consideration of any propellant system and the calculation of performance with dissociation effects. The new extended program is referred to as NNEP89.

  15. Residual Nuclide Production by Proton-Induced Reactions on Uranium for Energies between 20 and 70 MeV

    SciTech Connect

    Uosif, M.A.M.; Michel, R.; Herpers, U.; Kubik, P.-W.; Duijvestijn, M.; Koning, A.

    2005-05-24

    Within the HINDAS project, proton-irradiation experiments were performed at the injector cyclotron of the Paul Scherrer Institute at Villigen/Switzerland in order to investigate the production of residual nuclides from natural uranium. The stacked-foil technique was used to cover proton energies between 20 MeV and 70 MeV. Copper targets were used for monitoring the proton beam using the reaction 65Cu (p,n)65Zn. Residual radionuclides were measured by off-line {gamma}-spectrometry. Excitation functions were obtained for the production of 91Y, 95Zr, 95mNb, 99Mo, 103Ru, 112Pd, 115Cd, 124Sb, 126Sb, 127Sb, 132Te, 131I, 134Cs, 136Cs, 137Cs, 140Ba, 141Ce, 144Ce, 147Nd, and 238Np. The experimental data are compared to the sparse results of earlier measurements and with theoretical excitation functions calculated by the newly developed TALYS code. Good agreement between theory and experiment was obtained for product masses up to 115. For higher-mass fission products and for 238Np, there are still systematic deviations between theory and experiment. These deviations are discussed as deficits of the fission model in the heavy part of the fission product distribution.

  16. Residual Nuclide Production by Proton-Induced Reactions on Uranium for Energies between 20 and 70 MeV

    NASA Astrophysics Data System (ADS)

    Uosif, M. A. M.; Michel, R.; Herpers, U.; Kubik, P.-W.; Duijvestijn, M.; Koning, A.

    2005-05-01

    Within the HINDAS project, proton-irradiation experiments were performed at the injector cyclotron of the Paul Scherrer Institute at Villigen/Switzerland in order to investigate the production of residual nuclides from natural uranium. The stacked-foil technique was used to cover proton energies between 20 MeV and 70 MeV. Copper targets were used for monitoring the proton beam using the reaction 65Cu (p,n)65Zn. Residual radionuclides were measured by off-line γ-spectrometry. Excitation functions were obtained for the production of 91Y, 95Zr, 95mNb, 99Mo, 103Ru, 112Pd, 115Cd, 124Sb, 126Sb, 127Sb, 132Te, 131I, 134Cs, 136Cs, 137Cs, 140Ba, 141Ce, 144Ce, 147Nd, and 238Np. The experimental data are compared to the sparse results of earlier measurements and with theoretical excitation functions calculated by the newly developed TALYS code. Good agreement between theory and experiment was obtained for product masses up to 115. For higher-mass fission products and for 238Np, there are still systematic deviations between theory and experiment. These deviations are discussed as deficits of the fission model in the heavy part of the fission product distribution.

  17. Coupled flexural-torsional vibrations of anisotropic bars from polymer composite materials. II - Comparisons of calculated and experimental data for carbon-fiber composite bars

    NASA Astrophysics Data System (ADS)

    Ekel'Chik, V. S.; Perren, A. A.; Riabov, V. M.; Iartsev, B. A.

    1992-04-01

    A number of primary natural frequencies of flexural and torsional vibrations are determined experimentally for specimens cut from a unidirectional CFRP plate at the angles phi = 0, 90 deg to the reinforcement direction. The flexural and torsional vibration values yielded primary values of elasticity and shear moduli, which were then corrected on the basis of a comparison of the experimental data and theoretical calculations of the frequencies of coupled flexural-torsional vibrations of specimens cut at angles of 15, 30, 45, 60 and 75 deg. Good agreement between the calculated and experimental data is obtained, and it is shown that the flexural-torsional interaction must be considered in studying the natural vibrations for specimens whose longitudinal axes do not coincide with the elasticity symmetry axis.

  18. MAGMIX: a basic program to calculate viscosities of interacting magmas of differing composition, temperature, and water content

    USGS Publications Warehouse

    Frost, T.P.; Lindsay, J.R.

    1988-01-01

    MAGMIX is a BASIC program designed to predict viscosities at thermal equilibrium of interacting magmas of differing compositions, initial temperatures, crystallinities, crystal sizes, and water content for any mixing proportion between end members. From the viscosities of the end members at thermal equilibrium, it is possible to predict the styles of magma interaction expected for different initial conditions. The program is designed for modeling the type of magma interaction between hypersthenenormative magmas at upper crustal conditions. Utilization of the program to model magma interaction at pressures higher than 200 MPa would require modification of the program to account for the effects of pressure on heat of fusion and magma density. ?? 1988.

  19. Calculation of effective conductivity of 2D and 3D composite materials with anisotropic constituents and different inclusion shapes in Mathematica

    NASA Astrophysics Data System (ADS)

    Gómez-Muñoz, José Luis; Bravo-Castillero, Julián

    2008-08-01

    The study of the effective properties of composite materials with anisotropic constituents and different inclusion shapes has motivated the development of the Mathematica 6.0 package "CompositeMaterials". This package can be used to calculate the effective anisotropic conductivity tensor of two-phase composites. Any fiber cross section, even percolating ones, can be studied in the 2D composites. "Rectangular Prism" and "Ellipsoidal" inclusion shapes with arbitrary orientations can be investigated in the 3D composites. This package combines the Asymptotic Homogenization Method and the Finite Element Method in order to obtain the effective conductivity tensor. The commands and options of the package are illustrated with two sample applications for two- and three-dimensional composites. Program summaryProgram title:CompositeMaterials Catalogue identifier:AEAU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAU_v1_0.html Program obtainable from:CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions:Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.:132 183 No. of bytes in distributed program, including test data, etc.:1 334 908 Distribution format:tar.gz Programming language:Mathematica 6.0 Computer:Any that can run Mathematica 6.0 and where the open-source free C-programs Triangle ( http://www.cs.cmu.edu/ quake/triangle.html) and TetGen ( http://tetgen.berlios.de/) can be compiled and executed. Tested in Intel Pentium computers. Operating system:Any that can run Mathematica 6.0 and where the open-source free C-programs Triangle ( http://www.cs.cmu.edu/ quake/triangle.html) and TetGen ( http://tetgen.berlios.de/) can be compiled and executed. Tested in Windows XP. RAM:Small two-dimensional calculations require less than 100 MB. Large three-dimensional calculations require 500 MB or more. Classification:7.9 External routines:One Mathematica Add-on and

  20. Self-consistent method to calculate fiber interactions in a SiC/Al{sub 2}O{sub 3} ceramic composite

    SciTech Connect

    Bertinetti, M.A.; Turner, P.A.; Bolmaro, R.E.; Tome, C.N.

    1996-06-01

    The sintering of Al{sub 2}O{sub 3}/SiC ceramic composite leads to a state of high internal stresses in the composite material at room temperature because of the difference in thermal contraction between matrix and particles. It has been shown in a previous work that the interaction among fibers must be accounted for in order to predict correctly the residual stresses. In the present paper, the authors develop a numerical scheme that permits taking into account such interaction for an arbitrary distribution of fiber directions (DFD) and for completely anisotropic properties of the phases. They apply the formulation to calculate the average strain in the matrix (due to the interaction among fibers) and the effective thermal coefficients of the composite. They find that the average strain in the matrix depends strongly on the DFD and that the predictions agree with measurements done by Majumdar and Kupperman. They prove that the effective thermal coefficients of the composite are not sensitive to the DFD when the matrix and the fibers exhibit isotropic thermal and elastic properties. Finally, the authors analyze the effect of the DFD and of the fiber interaction on the internal stresses inside the SiC fibers and compare with experimental values.

  1. Ni(NiO)/single-walled carbon nanotubes composite: Synthesis of electro-deposition, gas sensing property for NO gas and density functional theory calculation

    SciTech Connect

    Li, Li; Zhang, Guo; Chen, Lei; Bi, Hong-Mei; Shi, Ke-Ying

    2013-02-15

    Graphical abstract: The Ni(NiO)/semiconducting single-walled carbon nanotubes composite collected from the cathode after electro-deposition shows a high sensitivity to low-concentration NO gas at room temperature (18 °C). Display Omitted Highlights: ► Ni(NiO) nanoparticles were deposited on semiconducting SWCNTs by electro-deposition. ► Ni(NiO)/semiconducting SWCNTs film shows a high sensitivity to NO gas at 18 °C. ►Theoretical calculation reveals electron transfer from SWCNTs to NO via Ni. -- Abstract: Single-walled carbon nanotubes which contains metallic SWCNTs (m-SWCNTs) and semiconducting SWCNTs (s-SWCNTs) have been obtained under electric arc discharge. Their separation can be effectively achieved by the electro-deposition method. The Ni(NiO)/s-SWCNTs composite was found on cathode where Ni was partially oxidized to NiO at ambient condition with Ni(NiO) nanoparticles deposited uniformly on the bundles of SWCNTs. These results were confirmed by Raman spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis–NIR and TG characterizations. Furthermore, investigation of the gas sensing property of Ni(NiO)/s-SWCNTs composite film to NO gas at 18 °C demonstrated the sensitivity was approximately 5% at the concentration of 97 ppb. Moreover, density functional theory (DFT) calculations were performed to explore the sensing mechanism which suggested the adsorption of NO molecules onto the composite through N–Ni interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.

  2. Computer Program for Calculation of Complex Chemical Equilibrium Compositions, Rocket Performance, Incident and Reflected Shocks, and Chapman-Jouguet Detonations. Interim Revision, March 1976

    NASA Technical Reports Server (NTRS)

    Gordon, S.; Mcbride, B. J.

    1976-01-01

    A detailed description of the equations and computer program for computations involving chemical equilibria in complex systems is given. A free-energy minimization technique is used. The program permits calculations such as (1) chemical equilibrium for assigned thermodynamic states (T,P), (H,P), (S,P), (T,V), (U,V), or (S,V), (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. The program considers condensed species as well as gaseous species.

  3. Cross Sections of P-Induced Reactions up to 100 MeV for the Interpretation of Solar Cosmic Ray Produced Nuclides

    NASA Astrophysics Data System (ADS)

    Schiekel, T.; Rosel, R.; Herpers, U.; Bodemann, R.; Michel, R.; Dittrich, B.; Hofmann, H. J.; Suter, M.; Wolfli, W.; Holmqvist, B.; Conde, H.; Malmborg, P.

    1992-07-01

    Integral excitation functions for the production of residual nuclides by proton-induced reactions are the basic data for an accurate modelling of the interactions of solar cosmic ray (SCR) particles with extraterrestrial matter. Due to the relatively low energies (<200 MeV/A) of SCR particles the production of nuclear active secondary particles can be widely neglected and theoretical production rate depth profiles can be calculated by simply folding the depth dependent SCR spectra with thin target cross sections of the underlying nuclear reactions. The accuracy of such calculations exclusively depends on the quality of the available cross sections. For many nuclides, in particular for long-lived radionuclides and stable rare gas isotopes, the exis- ting cross section database is neither comprehensive nor reliable. Therefore, we started a series of experiments to improve this situation. Eighteen elements (C, N as Si3N4, O as SiO2, Mg, Al, Si, Ti, V, Mn as Mn/Ni-alloy, Fe, Co, Ni, Cu, Zr, Nb, Rh, Ba as Ba-contai- ning glass, and Au) were irradiated with 94 and 99 MeV protons at the external beam of the TSL-cyclotron at Uppsala. Cross sections were determined using the stacked foil technique. Beam monitoring was done by investigating the production of ^22Na from Al, for which evaluated cross sections exist. Residual nuclides were measured by X-, gamma- and accelerator-mass spectrometry. In order to check the quality of our experimental procedure some target elements (22 <= Z <= 28) were included in the new exper- iments, which had been formerly irradiated at Julich, at Louvain La Neuve, and at IPN Orsay. Comparisons between the earlier measurements (1,2) and the new cross sections showed excellent agreement. Up to now, cross sections were measured for more than 120 different reactions. Here, we report on the results obtained for the target elements C, N, O, Mg, Al, and Si. The status of experimental excitation functions for the production of some radionuclides

  4. A method of calculating of the thermodynamic properties and the composition of the explosion products of hydrocarbons and air under partial chemical equilibrium

    NASA Astrophysics Data System (ADS)

    Shargatov, V. A.

    2016-11-01

    We examined the approximate method to calculate composition and thermodynamic parameters of hydrocarbons-air nonequilibrium explosion products based on the assumption of the existence of a partial chemical equilibrium. With excellent accuracy of calculating thermodynamic properties and species mass fraction the respective stiff system of detailed kinetics differential equations can be replaced by the one differential equation or the two differential equations and a system of algebraic equations. This method is always consistent with the detailed kinetic mechanism. The constituent equations of the method were derived and the respective computer code written. We examine the applicability of the method by solving the test problem. The proposed method simulation results are in excellent agreement with the detailed kinetics model results corresponding the stiff ordinary differential equation solver including NO time histories.

  5. A new methodology to calculate the environmental protection index (Ep). A case study applied to a company producing composite materials.

    PubMed

    Siracusa, G; La Rosa, A D; Sterlini, S E

    2004-12-01

    Environmental indicators can be used as a first stage in progress towards comprehensive environmental impact measures [J. Environ. Manage 65/3 (2002) 285]. In this article, we develop a 'pollutant interaction matrix method' that allows calculation of a global environmental protection index (Ep) in order to verify the eco-compatibility of an industrial activity. Two methods are proposed for the Ep index evaluation (which represents the numerical measure of the environmental sustainability): the Direct Method (Epd) and the Weighted Method (Epw). Both methods need to define, in the whole industrial process, homogeneous sectors (defined as construction sites where activities of the same type are carried out). Furthermore, for each activity a set of parameters (t, duration of pollution effect, P, quantity of pollutant produced,G, hazard of the pollutant) are required to evaluate the relative pollution index Y. All indices calculations were carried out using a set of matrices. The correct use of Ep evaluation provides an improvement in the total environmental performance of companies because it points out possible critical operations in each homogeneous sector which require solutions. The methodology is applied to evaluate the environmental pollution risk of a company that produces polymer materials and to improve their environmental performance. The results obtained show that the whole productive process has a low environmental impact factor. Nevertheless the applied methodology puts in evidence some processes that generate local pollution in specific areas of the factory and which could be dangerous for the workers' health.

  6. Cosmogenic nuclide shielding corrections determined via MCNPX radiation transport and spallation cross sections

    NASA Astrophysics Data System (ADS)

    Argento, D.; Reedy, R. C.; Stone, J. O.

    2011-12-01

    Cosmogenic Nuclides (CNs) are a critical new tool for geomorphology, allowing researchers to date Earth surface events and measure process rates [1]. Prior to CNs, many of these events and processes had no absolute method for measurement and relied entirely on relative methods. Reliable absolute measurement methods impact research constraining ice age extents and provide important climatic data via well constrained erosion rates, etc. [2]. Continuing to improve CN methods is critical for these sciences. Significant progress has been made in the last two decades in refining the method and reducing analytic uncertainties [1,3]. CRONUS-Earth, a collaboration of cosmogenic nuclide researchers, has been developing calibration data and scaling methods to provide a self-consistent platform for use in interpreting nuclide concentration values into geologic data. However, several aspects of the radiation cascade have been exceedingly difficult to measure empirically with either accuracy or spatial extent. One such aspect is the angular distribution of secondary cosmic rays that are energetic enough to produce cosmogenic nuclides via spallation. Researchers studying the angular distribution of such cosmic rays have usually described the distribution as (cos(Θ))^m. Currently, the standard corrections, assume an m of 2.3, which is based on very sparse data sets with very limited spatial and altitude variation [1,4,5]. Researchers using CNs must know the production rate at the sample location, and then make corrections for the portion of the sky that is blocked by nearby topography. If the shielding correction model currently used is too simplistic, this introduces error into the final results. In this study, a Monte Carlo method radiation transport code, MCNPX is used to model the Galactic Cosmic Ray (GCR) radiation impinging on the upper atmosphere and tracks the resulting secondary particles through a model of the Earth's atmosphere. Angle and energy distributions are

  7. Impact of vegetation change on the mobility of uranium- and thorium-series nuclides in soils

    NASA Astrophysics Data System (ADS)

    Gontier, A.; Rihs, S.; Turpault, M.-P.; Chabaux, F.

    2012-04-01

    The effect of land cover change on chemical mobility and soil response was investigated using short- and long-lived nuclides from the U- and Th series. Indeed, the matching of these nuclides half-live to the pedogenic processes rates make these nuclides especially suitable to investigate either time or mechanism of transfers within a soil-water-plant system. This study was carried out from the experimental Breuil-Chenue site (Morvan mountains, France). The native forest (150 year-old) was partially clear-felled and replaced in 1976 by mono-specific plantations distributed in different stands. Following this cover-change, some mineralogical changes in the acid brown soil were recognized (Mareschal, 2008). Three soil sections were sampled under the native forest and the replanted oak and Douglas spruce stands respectively. The (238U), (234U), (230Th), (226Ra), (232Th) and (228Ra) activities were analysed by thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (MC-ICPMS) and gamma spectrometry. Significant differences in U, Th, and Ra activities were observed between the soils located under the native forest or the replanted-trees stands, mostly dominated by a large uranium mobilization from the replanted soils. Moreover, all the investigated U and Th-series activity ratios show a contrasted trend between the shallowest horizons (0-50cm) and the deepest one (below 50cm), demonstrating the chemical effect of the vegetation change on the shallow soil layers. Using a continuous open-system leaching model, the coupled radioactive disequilibria measured in the different soil layers permit to quantify the rate of the radionuclides mobilities. Reference: Mareschal, L., 2008. Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan) Université Henri Poincaré, Nancy-I.

  8. Are Scaling Models for Production of Cosmogenic Nuclides Isotope Specific? - Implications from Secondary Cosmic Ray Neutron Spectra Measurements

    NASA Astrophysics Data System (ADS)

    Wilcken, K.

    2015-12-01

    A necessary requirement in studies using in-situ cosmogenic isotopes is to convert the measured isotope concentrations to exposure ages or geomorphic process rates. This involves using an accepted reference production rate, derived experimentally at a calibration site that has independent age control, and applying scaling factors for latitude and altitude in order to calculate a site-specific production rate. Throughout the development of the in-situ cosmogenic dating method, although reference production rates are necessarily nuclide specific, the scaling factors were not. The first atmospheric scaling model by Lal and Peters [1967] and others that followed, were based on the principle that as the cosmic ray particle flux attenuates with depth, the energy spectrum of nucleons of energy below 400 MeV becomes invariant at atmospheric depths greater than 200 g/cm2(altitude < 12 km). Hence scaling factors would thus be isotope independent resulting in production rate ratios of different isotopes to be invariant as a function of altitude. However, recent models by Argento et al. [2012, 2015] and Lifton et al. [2014] suggest that the energy spectrum is not invariant and scaling factors should in fact be isotope specific. The essential feature of the new models is that the focus is on generating the energy spectrum of cosmic-ray nucleons that is then converted into scaling factors with known cross sections. To benchmark the new scaling models I have collated secondary cosmic-ray neutron spectra measurements from the last 20 years and utilised these to calculate site-specific production rates. When using both ground-based and airborne neutron spectra measurements, the result follows the general trend predicted by the new models requiring isotope specific scaling. In contrast, using only the ground-based measurements, which range from sea-level to ~4000 m in altitude, no evidence for isotope specific scaling is apparent.

  9. Study on immobilization and migration of nuclide u in superficial soil of uranium tailings pond

    NASA Astrophysics Data System (ADS)

    Chang, Zhe; Zhou, Shukui

    2017-05-01

    The uranium tailings in southern China was used as the object of study to study the fixation and migration characteristics of nuclide U in shallow tailings. The results showed that the precipitation of tailings in the tailings soil was not linearly related to the depth during the acid rain leaching process. Tailings soil in the role of fixatives, when the lime as a fixative, the tailings of different soil uranium in 20 days after the re-precipitation. However, when lime and ammonium phosphate were used as fixing agents, the cumulative precipitation of U had a significant effect, and the migration of uranium was inhibited.

  10. The control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment

    NASA Astrophysics Data System (ADS)

    von Blanckenburg, Friedhelm

    2006-02-01

    The study of a sample of river sediment enables the determination of spatially averaged denudation rates that provide an exceptional perspective on erosion and weathering processes that have taken place within a landscape. These measurements are done with in-situ-produced cosmogenic nuclides (e.g., 10Be, 26Al), mostly in quartz from alluvial sediment. Cosmogenic nuclides are produced when secondary cosmic rays interact with the very uppermost layer of the Earth's surface. They are produced within a characteristic depth scale of about 1 m, which means that the measured concentrations record an integrated denudation history while material passed through this depth interval. Depending on the denudation rate the resulting integration time scales are 10 3 to 10 5 years, and one obtains a robust long-term estimate of natural denudation that is relatively insensitive to short-term changes. The last 10 years have seen significant research activity using these methods, and an array of fascinating tectono-geomorphologic and geochemical insights are emerging. Amongst these is the ability to identify the physical and chemical processes with which a landscape responds to tectonic activity or climate change. A compilation of world-wide denudation rates in non-glaciated areas, that however, does not yet include some of the world's most active mountain belts, has resulted in the following findings, some of which have been unexpected: (1) No obvious relationship between precipitation or mean annual temperature and total denudation is apparent. (2) Topographic relief alone does not result in high rates of denudation. (3) Denudation rates are high in areas of landscape rejuvenation; that is triggered and controlled by tectonic activity (faulting, escarpment formation and retreat, rifting, surface uplift). (4) Rates of weathering (using a combination of cosmogenic nuclides and zirconium-normalised cation loss balances) co-vary primarily with physical erosion rates and much less with

  11. The control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment

    NASA Astrophysics Data System (ADS)

    von Blanckenburg, Friedhelm

    2005-09-01

    The study of a sample of river sediment enables the determination of spatially averaged denudation rates that provide an exceptional perspective on erosion and weathering processes that have taken place within a landscape. These measurements are done with in-situ produced cosmogenic nuclides (e.g. 10Be, 26Al), mostly in quartz from alluvial sediment. Cosmogenic nuclides are produced when secondary cosmic rays interact with the very uppermost layer of the Earth's surface. They are produced within a characteristic depth scale of about 1 m, which means that the measured concentrations record an integrated denudation history while material passed through this depth interval. Depending on the denudation rate the resulting integration time scales are 10 3 to 10 5 years, and one obtains a robust long-term estimate of natural denudation that is relatively insensitive to short-term changes. The last 10 years have seen significant research activity using these methods, and an array of fascinating tectono-geomorphologic and geochemical insights are emerging. Amongst these is the ability to identify the physical and chemical processes with which a landscape responds to tectonic activity or climate change. A compilation of world-wide denudation rates in non-glaciated areas, that however, does not yet include some of the world's most active mountain belts, has resulted in the following findings, some of which have been unexpected: (1) No obvious relationship between precipitation or mean annual temperature and total denudation is apparent. (2) Topographic relief alone does not result in high rates of denudation. (3) Denudation rates are high in areas of landscape rejuvenation; that is triggered and controlled by tectonic activity (faulting, escarpment formation and retreat, rifting, surface uplift). (4) Rates of weathering (using a combination of cosmogenic nuclides and zirconium-normalised cation loss balances) co-vary primarily with physical erosion rates and much less with

  12. Total and spontaneous fission half-lives of the uranium and plutonium nuclides

    SciTech Connect

    Holden, N.E.

    1984-01-01

    The total half-life and the half-life for spontaneous fission are evaluated for the various long-lived nuclides of interest. Recommended values are presented for /sup 232/U, /sup 233/U, /sup 234/U, /sup 235/U, /sup 236/U, /sup 238/U, /sup 236/Pu, /sup 238/Pu, /sup 239/Pu, /sup 240/Pu, /sup 241/Pu, /sup 242/Pu, and /sup 244/Pu. The uncertainties are provided at the 95% confidence limit for each of the recommended values.

  13. Prompt neutron fission spectrum mean energies for the fissile nuclides and /sup 252/Cf

    SciTech Connect

    Holden, N.E.

    1985-01-01

    The international standard for a neutron spectrum is that produced from the spontaneous fission of /sup 252/Cf, while the thermal neutron induced fission neutron spectra for the four fissile nuclides, /sup 233/U, /sup 235/U, /sup 239/Pu, and /sup 241/Pu are of interest from the standpoint of nuclear reactors. The average neutron energies of these spectra are tabulated. The individual measurements are recorded with the neutron energy range measured, the method of detection as well as the average neutron energy for each author. Also tabulated are the measurements of the ratio of mean energies for pairs of fission neutron spectra. 75 refs., 9 tabs. (LEW)

  14. Consistent neutron-physical and thermal-physical calculations of fuel rods of VVER type reactors

    NASA Astrophysics Data System (ADS)

    Tikhomirov, Georgy; Saldikov, Ivan; Ternovykh, Mikhail; Gerasimov, Alexander

    2017-09-01

    For modeling the isotopic composition of fuel, and maximum temperatures at different moments of time, one can use different algorithms and codes. In connection with the development of new types of fuel assemblies and progress in computer technology, the task makes important to increase accuracy in modeling of the above characteristics of fuel assemblies during the operation. Calculations of neutronphysical characteristics of fuel rods are mainly based on models using averaged temperature, thermal conductivity factors, and heat power density. In this paper, complex approach is presented, based on modern algorithms, methods and codes to solve separate tasks of thermal conductivity, neutron transport, and nuclide transformation kinetics. It allows to perform neutron-physical and thermal-physical calculation of the reactor with detailed temperature distribution, with account of temperature-depending thermal conductivity and other characteristics. It was applied to studies of fuel cell of the VVER-1000 reactor. When developing new algorithms and programs, which should improve the accuracy of modeling the isotopic composition and maximum temperature in the fuel rod, it is necessary to have a set of test tasks for verification. The proposed approach can be used for development of such verification base for testing calculation of fuel rods of VVER type reactors

  15. Eight-band k ṡp calculations of the composition contrast effect on the linear polarization properties of columnar quantum dots

    NASA Astrophysics Data System (ADS)

    Andrzejewski, Janusz; Sek, Grzegorz; O'Reilly, Eoin; Fiore, Andrea; Misiewicz, Jan

    2010-04-01

    We present eight-band k ṡp calculations of the electronic and polarization properties of columnar InzGa1-zAs quantum dots (CQD) with high aspect ratio embedded in an InxGa1-xAs/GaAs quantum well. Our model accounts for the linear strain effects, linear piezoelectricity, and spin-orbit interaction. We calculate the relative intensities of transverse-magnetic (TM) and transverse-electric (TE) linear polarized light emitted from the edge of the semiconductor wafer as a function of the two main factors affecting the heavy hole—light hole valence band mixing and hence, the polarization dependent selection rules for the optical transitions, namely, (i) the composition contrast z /x between the dot material and the surrounding well and (ii) the dot aspect ratio. The numerical results show that the former is the main driving parameter for tuning the polarization properties. This is explained by analyzing the biaxial strain in the CQD, based on which it is possible to predict the TM to TE intensity ratio. The conclusions are supported by analytical considerations of the strain in the dots. Finally, we present the compositional and geometrical conditions to achieve polarization independent emission from InGaAs/GaAs CQDs.

  16. Vanadium Pentoxide Nanobelt-Reduced Graphene Oxide Nanosheet Composites as High-Performance Pseudocapacitive Electrodes: ac Impedance Spectroscopy Data Modeling and Theoretical Calculations

    PubMed Central

    Gupta, Sanju; Aberg, Bryce; Carrizosa, Sara B.; Dimakis, Nicholas

    2016-01-01

    heterogeneous composite electrodes. We attribute the superior performance to the open graphene topological network being beneficial to available ion diffusion sites and the faster transport kinetics having a larger accessible geometric surface area and synergistic integration with optimal nanostructured VO loading. Computational simulations via periodic density functional theory (DFT) with and without V2O5 adatoms on graphene sheets are also performed. These calculations determine the total and partial electronic density of state (DOS) in the vicinity of the Fermi level (i.e., higher electroactive sites), in turn complementing the experimental results toward surface/interfacial charge transfer on heterogeneous electrodes. PMID:28773738

  17. Thermoelectric and piezoelectric properties of the predicted AlxIn1-xN composites based on ab initio calculations.

    PubMed

    Chang, Yee Hui Robin; Yoon, Tiem Leong; Lim, Thong Leng; Tuh, Moi Hua; Goh, Eong Sheng

    2017-09-20

    Theoretical investigations of the thermoelectric and piezoelectric characteristics in the AlxIn1-xN system have been carried out based on a first principles approach in combination with the semi-classical Boltzmann transport concept and density functional perturbation theory. Based on our previous work, herein, the study specimens Al5InN6, Al6In2N8, Al4In2N6, Al3In3N6, Al2In4N6, and AlIn7N8 have been predicted to be stable phases. These novel phases intrinsically exhibit moderate positive Seebeck curves (199.1-284.6 μV K(-1)) and a ZT close to unity that varies marginally over a broad temperature range of 200-800 K, demonstrating the sign of good bipolar effect tolerance. Addition of heftier elements, such as In, results in lower thermal conductivity, which in turn generates a high power factor (0.019-0.345 W m(-1) K(-2)) in these alloys. While hole doping enhances the peak Seebeck coefficient of each phase, the electrical conductivity has been greatly compromised, resulting in a lower power factor. These composites also exhibit large piezoelectric constants, in which their respective largest piezoelectric tensor is several orders higher than that of quartz. The decomposition process shows that In and N are the main contributors of the internal piezoelectric term. Overall results indicate that AlxIn1-xN show bright prospects in thermoelectric and piezoelectric applications.

  18. Calculating Time-Integral Quantities in Depletion Calculations

    DOE PAGES

    Isotalo, Aarno

    2016-06-02

    A method referred to as tally nuclides is presented for accurately and efficiently calculating the time-step averages and integrals of any quantities that are weighted sums of atomic densities with constant weights during the step. The method allows all such quantities to be calculated simultaneously as a part of a single depletion solution with existing depletion algorithms. Some examples of the results that can be extracted include step-average atomic densities and macroscopic reaction rates, the total number of fissions during the step, and the amount of energy released during the step. Furthermore, the method should be applicable with several depletionmore » algorithms, and the integrals or averages should be calculated with an accuracy comparable to that reached by the selected algorithm for end-of-step atomic densities. The accuracy of the method is demonstrated in depletion calculations using the Chebyshev rational approximation method. Here, we demonstrate how the ability to calculate energy release in depletion calculations can be used to determine the accuracy of the normalization in a constant-power burnup calculation during the calculation without a need for a reference solution.« less

  19. Calculating Time-Integral Quantities in Depletion Calculations

    SciTech Connect

    Isotalo, Aarno

    2016-06-02

    A method referred to as tally nuclides is presented for accurately and efficiently calculating the time-step averages and integrals of any quantities that are weighted sums of atomic densities with constant weights during the step. The method allows all such quantities to be calculated simultaneously as a part of a single depletion solution with existing depletion algorithms. Some examples of the results that can be extracted include step-average atomic densities and macroscopic reaction rates, the total number of fissions during the step, and the amount of energy released during the step. Furthermore, the method should be applicable with several depletion algorithms, and the integrals or averages should be calculated with an accuracy comparable to that reached by the selected algorithm for end-of-step atomic densities. The accuracy of the method is demonstrated in depletion calculations using the Chebyshev rational approximation method. Here, we demonstrate how the ability to calculate energy release in depletion calculations can be used to determine the accuracy of the normalization in a constant-power burnup calculation during the calculation without a need for a reference solution.

  20. Nuclear event zero-time calculation and uncertainty evaluation.

    PubMed

    Pan, Pujing; Ungar, R Kurt

    2012-04-01

    It is important to know the initial time, or zero-time, of a nuclear event such as a nuclear weapon's test, a nuclear power plant accident or a nuclear terrorist attack (e.g. with an improvised nuclear device, IND). Together with relevant meteorological information, the calculated zero-time is used to help locate the origin of a nuclear event. The zero-time of a nuclear event can be derived from measured activity ratios of two nuclides. The calculated zero-time of a nuclear event would not be complete without an appropriately evaluated uncertainty term. In this paper, analytical equations for zero-time and the associated uncertainty calculations are derived using a measured activity ratio of two nuclides. Application of the derived equations is illustrated in a realistic example using data from the last Chinese thermonuclear test in 1980. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  1. Transformative progress in glacial chronology by systematic advances in cosmogenic nuclide dating

    NASA Astrophysics Data System (ADS)

    Schaefer, J. M.; Finkel, R. C.; Denton, G.; Kaplan, M. R.; Putnam, A.; Schwartz, R.; Barrell, D.

    2010-12-01

    Terrestrial cosmogenic nuclide dating has recently advanced the field of Quaternary Geology. However, systematic uncertainties have remained considerable enough to hamper the application of cosmogenic techniques to some geological fields. It has been the major goal of the CRONUS-Earth initiative to push the systematic understanding of terrestrial cosmogenic nuclide techniques to new limits and, in turn, to broaden and deepen the earth scientific application spectrum. Here we report progress in 10Be surface exposure dating towards better precision, higher internal consistency, higher temporal resolution, bigger sample sets and better overall accuracy and its transformative character for using the global glacial record as climate archive. Based on a large set of unpublished high-precision data from Holocene erratic boulders on moraines in New Zealand’s Southern Alps, Patagonia and the Alps, we discuss the potential and limits for dating very young surfaces and present novel possibilities to tie the precise chronologies of the glacial event record to continuous-high resolution records, such as treerings and ice cores. These novel glacier chronologies afford for new insights into the underlying driving mechanisms, pointing to strong inter-hemispheric discrepancies. Finally, we will discuss the impact of this progress on fields like natural hazards and surface process rates in high-erosion environments to illustrate the value of CRONUS-Earth for the wider earth scientific community.

  2. Runoff and sediment yield model for predicting nuclide transport in watersheds using BIOTRAN

    SciTech Connect

    Gallegos, A.F.; Wenzel, W.J.

    1990-09-01

    The environmental risk simulation model BIOTRAN was interfaced with a series of new subroutines (RUNOFF, GEOFLX, EROSON, and AQUIFER) to predict the movement of nuclides, elements, and pertinent chemical compounds in association with sediments through lateral and channel flow of runoff water. In addition, the movement of water into and out of segmented portions of runoff channels was modeled to simulate the dynamics of moisture flow through specified aquifers within the watershed. The BIOTRAN soil water flux subroutine, WATFLX, was modified to interface the relationships found in the SPUR model for runoff and sediment transport into channels with the particle sorting relationships to predict radionuclide enrichment and movement in watersheds. The new subroutines were applied specifically to Mortandad Canyon within Los Alamos National Laboratory by simultaneous simulation of eight surface vegetational subdivisions and associated channel and aquifer segments of this watershed. This report focuses on descriptions of the construction and rationale for the new subroutines and on discussing both input characteristics and output relationships to known runoff events from Mortandad Canyon. Limitations of the simplified input on model behavior are also discussed. Uranium-238 was selected as the nuclide for demonstration of the model because it could be assumed to be homogeneously distributed over the watershed surface. 22 refs., 18 figs., 9 tabs.

  3. HALF-LIVES OF LONG-LIVED A-DECAY, B-DECAY, BB-DECAY AND SPONTANEOUS FISSION NUCLIDES.

    SciTech Connect

    HOLDEN,N.E.

    2001-06-29

    In his review of radionuclides for dating purposes, Roth noted that there were a large number of nuclides, normally considered ''stable'' but which are radioactive with a very long half-life. Roth suggested that I review the data on the half-life values of these long-lived nuclides for a discussion session at the next meeting. These half-life values for long-lived nuclides include those due to various decay modes, {alpha}-decay, {beta}-decay, electron capture decay, {beta}{beta}-decay and spontaneous fission decay. This report is preliminary but will provide a quick overview of the extensive table of data on the recommendations from that review.

  4. Apparatus and method for quantitatively evaluating total fissile and total fertile nuclide content in samples. [Patent application

    DOEpatents

    Caldwell, J.T.; Kunz, W.E.; Cates, M.R.; Franks, L.A.

    1982-07-07

    Simultaneous photon and neutron interrogation of samples for the quantitative determination of total fissile nuclide and total fertile nuclide material present is made possible by the use of an electron accelerator. Prompt and delayed neutrons produced from resulting induced fission are counted using a single detection system and allow the resolution of the contributions from each interrogating flux leading in turn to the quantitative determination sought. Detection limits for /sup 239/Pu are estimated to be about 3 mg using prompt fission neutrons and about 6 mg using delayed neutrons.

  5. Electrocatalytic Zinc Composites as the Efficient Counter Electrodes of Dye-Sensitized Solar Cells: Study on the Electrochemical Performances and Density Functional Theory Calculations.

    PubMed

    Li, Chun-Ting; Chang, Hung-Yu; Li, Yu-Yan; Huang, Yi-June; Tsai, Yu-Lin; Vittal, R; Sheng, Yu-Jane; Ho, Kuo-Chuan

    2015-12-30

    Highly efficient zinc compounds (Zn3N2, ZnO, ZnS, and ZnSe) have been investigated as low-cost electrocatalysts for the counter electrodes (CE) of dye-sensitized solar cells (DSSCs). Among them, Zn3N2 and ZnSe are introduced for the first time in DSSCs. The zinc compounds were separately mixed with a conducting binder, poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) ( PSS), and thereby four composite films of Zn3N2/PEDOT:PSS, ZnO/PEDOT:PSS, ZnS/PEDOT:PSS, and ZnSe/ PSS were coated on the tin-doped indium oxide (ITO) substrates through a simple drop-coating process. In the composite film, nanoparticles of the zinc compound form active sites for the electrocatalytic reduction of triiodide ions, and PSS provides a continuous conductive matrix for fast electron transfer. By varying the weight percentage (5-20 wt %) of a zinc compound with respect to the weight of the PSS, the optimized concentration of a zinc compound was found to be 10 wt % in all four cases, based on the photovoltaic performances of the corresponding DSSCs. At this concentration (10 wt %), the composites films with Zn3N2 (Zn3N2-10), ZnO (ZnO-10), ZnS (ZnS-10), and ZnSe (ZnSe-10) rendered, for their DSSCs, power conversion efficiencies (η) of 8.73%, 7.54%, 7.40%, and 8.13%, respectively. The difference in the power conversion efficiency is explained based on the electrocatalytic abilities of those composite films as determined by cyclic voltammetry (CV), Tafel polarization plots, and electrochemical impedance spectroscopy (EIS) techniques. The energy band gaps of the zinc compounds, obtained by density functional theory (DFT) calculations, were used to explain the electrocatalytic behaviors of the compounds. Among all the zinc-based composites, the one with Zn3N2-10 showed the best electrocatalytic ability and thereby rendered for its DSSC the highest η of 8.73%, which is even higher than that of the cell with the traditional Pt CE (8.50%). Therefore, Zn3N2 can be considered as a promising

  6. Comparing Time-Dependent Geomagnetic and Atmospheric Effects on Cosmogenic Nuclide Production Rate Scaling

    NASA Astrophysics Data System (ADS)

    Lifton, N. A.

    2014-12-01

    A recently published cosmogenic nuclide production rate scaling model based on analytical fits to Monte Carlo simulations of atmospheric cosmic ray flux spectra (both of which agree well with measured spectra) (Lifton et al., 2014, Earth Planet. Sci. Lett. 386, 149-160: termed the LSD model) provides two main advantages over previous scaling models: identification and quantification of potential sources of bias in the earlier models, and the ability to generate nuclide-specific scaling factors easily for a wide range of input parameters. The new model also provides a flexible framework for exploring the implications of advances in model inputs. In this work, the scaling implications of two recent time-dependent spherical harmonic geomagnetic models spanning the Holocene will be explored. Korte and Constable (2011, Phys. Earth Planet. Int. 188, 247-259) and Korte et al. (2011, Earth Planet. Sci. Lett. 312, 497-505) recently updated earlier spherical harmonic paleomagnetic models used by Lifton et al. (2014) with paleomagnetic measurements from sediment cores in addition to archeomagnetic and volcanic data. These updated models offer improved accuracy over the previous versions, in part to due to increased temporal and spatial data coverage. With the new models as input, trajectory-traced estimates of effective vertical cutoff rigidity (RC- the standard method for ordering cosmic ray data) yield significantly different time-integrated scaling predictions when compared to the earlier models. These results will be compared to scaling predictions using another recent time-dependent spherical harmonic model of the Holocene geomagnetic field by Pavón-Carrasco et al. (2014, Earth Planet. Sci. Lett. 388, 98-109), based solely on archeomagnetic and volcanic paleomagnetic data, but extending to 14 ka. In addition, the potential effects of time-dependent atmospheric models on LSD scaling predictions will be presented. Given the typical dominance of altitudinal over

  7. Regional Dispersal of Fukushima-derived Fission Nuclides by East Asia Monsoon

    NASA Astrophysics Data System (ADS)

    Huh, Chih-An; Lin, Chuan-Yao; Hsu, Shih-Chieh

    2013-04-01

    Since the Fukushima nuclear accident happened on 12 March 2011, there have been a plethora of publications about the dispersion of radioactive material from the damaged reactors. Most of these works dealt with global transport of Fukushima-derived radionuclides in the northern hemisphere and local transport in the vicinity of Fukushima and around Japan. In contrast, few works investigated into dispersal of radiation plumes from Japan to other areas on regional scales. This is because regional dispersal out of Japan in the springtime is most likely dominated by the northeastern monsoon, whereas there are few monitoring stations downwind in the southeastern Asia region. In this respect, we are only aware of the data in Vietnam published by Long et al (2012) in addition to our own data obtained in and around Taiwan (Huh et al., 2012; Hsu et al., 2012). By integrating the data published in the literature plus those that can be searched from relevant websites, we try to further elucidate the dispersal of Fukushima-derived radiation toward the southeastern Asia region. The WRF/Chem tracer model is employed to simulate the dispersal of radiation plumes from the damaged Fukushima Daiichi Nuclear Power Plant. From a vis-à-vis comparison between the model simulation and the time-series of Fukushima-derived fission nuclides monitored around the southeastern Asia, we can distinguish between global transport by the Westerlies in the free troposphere and regional transport by the northeast monsoon in the planetary boundary layer. In general, regional (mainly meridional) transport carried more weight than global (mainly zonal) transport in contributing Fukushima-derived radioactivity to the area covered in this review, particularly at the ground-level sites. References 1. Hsu, S.C., Huh, C.A., Chan, C.Y., Lin, S.H., Lin, F.J. and Liu, S.C. (2012). Hemispheric dispersion of radioactive plume laced with fission nuclides from the Fukushima nuclear event. Geophys. Res. Lett. 39, L00

  8. REVIEW OF RESULTS FOR THE OECD/NEA PHASE VII BENCHMARK: STUDY OF SPENT FUEL COMPOSITIONS FOR LONG TERM DISPOSAL

    SciTech Connect

    Radulescu, Georgeta; Wagner, John C

    2011-01-01

    This paper summarizes the problem specification and compares participants results for the OECD/NEA/WPNCS Expert Group on Burn-up Credit Criticality Safety Phase VII Benchmark Study of Spent Fuel Compositions for Long-Term Disposal. The Phase VII benchmark was developed to study the ability of relevant computer codes and associated nuclear data to predict spent fuel isotopic compositions and corresponding keff values in a cask configuration over the time duration relevant to spent nuclear fuel (SNF) disposal. The benchmark was divided into two sets of calculations: (1) decay calculations out to 1,000,000 years for provided pressurized-water-reactor (PWR) UO2 discharged fuel compositions and (2) burnup credit criticality calculations for a representative cask model at selected time steps. Contributions from 15 organizations and companies in 10 countries were submitted to the Phase VII benchmark exercise. This paper provides a description of the Phase VII benchmark and detailed comparisons of the participants isotopic compositions and keff values that were calculated with a diversity of computer codes and nuclear data sets. Differences observed in the calculated time-dependent nuclide densities are attributed to different decay data or code-specific numerical approximations. The variability of the keff results is consistent with the evaluated uncertainty associated with cross-section data.

  9. Calculation of CO2 activities using scapolite equilibria: constraints on the presence and composition of a fluid phase during high grade metamorphism

    NASA Astrophysics Data System (ADS)

    Moecher, David P.; Essene, Eric J.

    1991-07-01

    Thermodynamic and phase equilibrium data for scapolite have been used to calculate CO2 activities ( aCO2) and to evaluate the presence or absence of a fluid phase in high-grade scapolite bearing meta-anorthosite, granulites, calc-silicates, and mafix xenoliths. The assemblage scapolite-plagioclase-garnet±quartz may be used to calculate or limit aCO2 by the reaction Meionite+Quartz = Grossular+Anorthite+CO2. Granulites from four high-grade terranes (Grenville Province, Canada; Sargut Belt, India; Furua Complex, Tanzania; Bergen Arcs, Norway) yield aCO2=0.4-1, with most >0.7. For scapolite-bearing granulites from the Furua Complex, in which aCO2≥0.9, calculated H2O activities ( aH2O) based on phlogopite dehydration equilibria are uniformly low (0.1 0.2). The aCO2 calculated for meta-anorthosite from the Grenville Province, Ontario, ranges from 0.2 to 0.8. For Grenville meta-anorthosite also containing epidote, the aH2O calculated from clinozoisite dehydration ranges from 0.2 to 0.6. Calc-silicates from the Grenville, Sargur, and Furua terranes mostly yield aCO2< 0.5. The presence of calcite and/or wollastonite provides additional evidence for the low aCO2 in calc-silicates. Samples from six xenolith localities (Lashaine, Tanzania; Eifel, W. Germany; Lesotho; Delegate, Gloucester, and Hill 32, Australia) yield a wide range of aCO2 (0.1 to >1). The calculated fluid activities are consistent with metamorphism (1) in the presence of a mixed CO2-H2O fluid phase in which CO2 is the dominant fluid species but other C-O-H-S species are minor, (2) in the absence of a bulk fluid phase (“fluid-absent metamorphism”), or (3) in the presence of a fluid-bearing melt phase. The results for many granulites and Grenville meta-anorthosite are consistent with the presence of a CO2-rich, mixed CO2-H2O fluid phase. In contrast the relatively restricted and low values of aCO2 for calc-silicates require an H2O-rich fluid or absence of a fluid phase during metamorphism. The range of

  10. A Method for Calculating Strain Energy Release Rates in Preliminary Design of Composite Skin/Stringer Debonding Under Multi-Axial Loading

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Minguet, Pierre J.; OBrien, T. Kevin

    1999-01-01

    Three simple procedures were developed to determine strain energy release rates, G, in composite skin/stringer specimens for various combinations of unaxial and biaxial (in-plane/out-of-plane) loading conditions. These procedures may be used for parametric design studies in such a way that only a few finite element computations will be necessary for a study of many load combinations. The results were compared with mixed mode strain energy release rates calculated directly from nonlinear two-dimensional plane-strain finite element analyses using the virtual crack closure technique. The first procedure involved solving three unknown parameters needed to determine the energy release rates. Good agreement was obtained when the external loads were used in the expression derived. This superposition technique was only applicable if the structure exhibits a linear load/deflection behavior. Consequently, a second technique was derived which was applicable in the case of nonlinear load/deformation behavior. The technique involved calculating six unknown parameters from a set of six simultaneous linear equations with data from six nonlinear analyses to determine the energy release rates. This procedure was not time efficient, and hence, less appealing. A third procedure was developed to calculate mixed mode energy release rates as a function of delamination lengths. This procedure required only one nonlinear finite element analysis of the specimen with a single delamination length to obtain a reference solution for the energy release rates and the scale factors. The delamination was extended in three separate linear models of the local area in the vicinity of the delamination subjected to unit loads to obtain the distribution of G with delamination lengths. This set of sub-problems was Although additional modeling effort is required to create the sub- models, this local technique is efficient for parametric studies.

  11. Evaluation and Parameter Analysis of Burn up Calculations for the Assessment of Radioactive Waste - 13187

    SciTech Connect

    Fast, Ivan; Aksyutina, Yuliya; Tietze-Jaensch, Holger

    2013-07-01

    Burn up calculations facilitate a determination of the composition and nuclear inventory of spent nuclear fuel, if operational history is known. In case this information is not available, the total nuclear inventory can be determined by means of destructive or, even on industrial scale, nondestructive measurement methods. For non-destructive measurements however only a few easy-to-measure, so-called key nuclides, are determined due to their characteristic gamma lines or neutron emission. From these measured activities the fuel burn up and cooling time are derived to facilitate the numerical inventory determination of spent fuel elements. Most regulatory bodies require an independent assessment of nuclear waste properties and their documentation. Prominent part of this assessment is a consistency check of inventory declaration. The waste packages often contain wastes from different types of spent fuels of different history and information about the secondary reactor parameters may not be available. In this case the so-called characteristic fuel burn up and cooling time are determined. These values are obtained from a correlations involving key-nuclides with a certain bandwidth, thus with upper and lower limits. The bandwidth is strongly dependent on secondary reactor parameter such as initial enrichment, temperature and density of the fuel and moderator, hence the reactor type, fuel element geometry and plant operation history. The purpose of our investigation is to look into the scaling and correlation limitations, to define and verify the range of validity and to scrutinize the dependencies and propagation of uncertainties that affect the waste inventory declarations and their independent verification. This is accomplished by numerical assessment and simulation of waste production using well accepted codes SCALE 6.0 and 6.1 to simulate the cooling time and burn up of a spent fuel element. The simulations are benchmarked against spent fuel from the real reactor

  12. Composites

    NASA Astrophysics Data System (ADS)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  13. TUNL Nuclear Structure Data Evaluation on A = 2-20 Nuclides

    NASA Astrophysics Data System (ADS)

    Truong, Thinh; Kelley, John; Sheu, Grace

    2016-09-01

    Nuclear data represents measured or evaluated probabilities of various physical interactions involving the nuclei of atoms. The nuclear data group at Triangle Universities Nuclear Laboratory (TUNL) compiles, evaluates and disseminates nuclear structure data relevant to light nuclei in the mass region of A = 2 - 20. Our activities primarily involve surveying literature articles and producing recommended values for inclusion into various United States Nuclear Data Program databases, such as Experimental Unevaluated Nuclear Data List (XUNDL) and Evaluated Nuclear Structure Data File (ENSDF). We have projects related to analyzing beta-decay lifetimes, compiling structure data from recently published articles, and producing full nuclear structure data evaluations of nuclides based on all existing literature. The nuclear data disseminated is used for theoretical model development of nuclear physics and for applications involving radiation and nuclear power technologies. This work is supported by the U.S. National Science Foundation Grant No. NSF-PHY-1461204 and Duke/TUNL.

  14. Direct mass measurement of the four-neutron halo nuclide 8He.

    PubMed

    Ryjkov, V L; Brodeur, M; Brunner, T; Smith, M; Ringle, R; Lapierre, A; Ames, F; Bricault, P; Dombsky, M; Delheij, P; Lunney, D; Pearson, M R; Dilling, J

    2008-07-04

    A high-precision Penning trap mass measurement of the exotic 8He nuclide (T(1/2)=119 ms) has been carried out resulting in a reduction of the uncertainty of the halo binding energy by over an order of magnitude. The new mass, determined with a relative uncertainty of 9.2 x 10(-8) (deltam=690 eV) is 13 keV less bound than the previously accepted value. The mass measurement is of great relevance for the recent charge-radius measurement of 8He [P. Mueller, Phys. Rev. Lett. 99, 252501 (2007).10.1103/PhysRevLett.99.252501]. The 8He mass is the first result from the newly-commissioned Penning trap: TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at the ISAC (Isotope Separator and Accelerator) radioactive beam facility at TRIUMF.

  15. Total and spontaneous fission half-lives for americium and curium nuclides

    SciTech Connect

    Holden, N.E.

    1985-01-01

    The long-lived nuclides of the americium curium elements are of interest for their use in certain safeguard applications and for nuclear reactor burnup studies in waste management. Recommended values are presented for /sup 241,242m,243/Am, and for /sup 242,243,244,245,246,247,248,250/Cm. These values result from a consistent evaluation of all these half-lives. These preliminary estimates were presented earlier. The uncertainties are provided at the 95% confidence limit for each of the recommended values. It will be noted that many of the recommended errors considerably exceed errors quoted by individual authors in their publication, by up to an order of magnitude, e.g., the total half-life of /sup 242,246,248/Cm and the spontaneous fission half-life of /sup 244/Cm. 65 refs., 18 tabs.

  16. Total and spontaneous fission half-lives for americium and curium nuclides

    NASA Astrophysics Data System (ADS)

    Holden, N. E.

    The long-lived nuclides of the americium curium elements are of interest for their use in certain safeguard applications and for nuclear reactor burnup studies in waste management. Recommended values are presented for /sup 241,242m,243/Am, and for /sup 242,243,244,245,246,247,248,250/Cm. These values result from a consistent evaluation of all these half-lives. These preliminary estimates were presented earlier. The uncertainties are provided at the 95% confidence limit for each of the recommended values. It will be noted that many of the recommended errors considerably exceed errors quoted by individual authors in their publication, by up to an order of magnitude, e.g., the total half-life of /sup 242,246,248/Cm and the spontaneous fission half-life of (244)Cm.

  17. Beta-spectroscopy of long lived nuclides with a PIPS detector-setup

    NASA Astrophysics Data System (ADS)

    Domula, Alexander R.; Thurn, Jan; Zuber, Kai

    2017-09-01

    Several applications in modern nuclear physics, research and engineering are limited by a lack of precise knowledge in spectral shape data for beta-decays. Specifically the interest aims to study spectral data for forbidden decays with respectively long half-lives, which is one of the central activities of our group. For the investigation of those rare beta-decays the group operates a setup of six PIPS detectors in a vacuum chamber built out of low-radioactivity materials. In the long term the setup will be used as low-background-detector for the investigation of rare beta-decays. In order to reduce the measuring-background a muon veto was installed. The characterization of the setup in the energy-range from 20..1000 keV using conversion-electrons is described. A set of useful calibration-nuclides was established to determine energy calibration and efficiencies.

  18. Patterns of cosmogenic nuclide acquisition in the Sierra Nevada, Southern Spain

    NASA Astrophysics Data System (ADS)

    Reinhardt, L.; Bishop, P.; Dempster, T.; Hoey, T.; Fifield, K.; Barrows, T.

    2003-04-01

    Tectonically active mountain ranges are expected to respond rapidly to changes in base level. Sediment derived from such areas are expected to be rapidly delivered to sedimentary basins. A comprehensive terrestrial cosmogenic nuclide-based study aims to test these assumptions in an actively uplifting mountain block and to investigate particle transport paths prior to final deposition. The Sierra Nevada of western Spain is a tectonically active mountain range on the southern margin of the Eurasian plate. Thermochronological data indicate that the present day topography (maximum elevation 3480m) has developed within the past 10 Ma Our study focuses on the Rio Torrente catchment, a small (9km × 3km) east-west trending, 2000m relief catchment in the western Sierra Nevada. The Torrente has a denudationally stable headwater region of thick regolith cover and low slope angles, which passes abruptly downstream across a major knickpoint into the very steep topography of a drainage net that is currently experiencing a rejuvenation event. Frequent shallow bedrock landslides, promoted by a strong northward dipping bedrock schistosity, dominate rejuvenated areas. The distribution of Be-10 concentrations in sediment and bedrock corresponds very well with observed geomorphic processes within the Rio Torrente Catchment. Be-10 concentrations as low as 10 000 atoms/gram in bedrock and sediment, corresponding to apparent erosion rates in excess of 2mm per annum, characterise the steep landslide-dominated lower catchment. Areas of the catchment as yet unaffected by rejuvenation are readily identifiable through their relatively high Be-10 contents. GIS based data analysis, involving a simple tracking of particles across the landscape to estimate elevation histories during particle exhumation and transport, enables identification of the pattern of nuclide acquisition as sediment is generated and transported through the Rio Torrente Catchment.

  19. Early Acheulean technology in the Rietputs Formation, South Africa, dated with cosmogenic nuclides.

    PubMed

    Gibbon, Ryan J; Granger, Darryl E; Kuman, Kathleen; Partridge, Timothy C

    2009-02-01

    An absolute dating technique based on the build-up and decay of (26)Al and (10)Be in the mineral quartz provides crucial evidence regarding early Acheulean hominid distribution in South Africa. Cosmogenic nuclide burial dating of an ancient alluvial deposit of the Vaal River (Rietputs Formation) in the western interior of South Africa shows that coarse gravel and sand aggradation there occurred ca 1.57+/-0.22Ma, with individual ages of samples ranging from 1.89+/-0.19 to 1.34+/-0.22Ma. This was followed by aggradation of laminated and cross-bedded fine alluvium at ca 1.26+/-0.10Ma. The Rietputs Formation provides an ideal situation for the use of the cosmogenic nuclide burial dating method, as samples could be obtained from deep mining pits at depths ranging from 7 to 16 meters. Individual dates provide only a minimum age for the stone tool technology preserved within the deposits. Each assemblage represents a time averaged collection. Bifacial tools distributed throughout the coarse gravel and sand unit can be assigned to an early phase of the Acheulean. This is the first absolute radiometric dated evidence for early Acheulean artefacts in South Africa that have been found outside of the early hominid sites of the Gauteng Province. These absolute dates also indicate that handaxe-using hominids inhabited southern Africa as early as their counterparts in East Africa. The simultaneous appearance of the Acheulean in different parts of the continent implies relatively rapid technology development and the widespread use of large cutting tools in the African continent by ca 1.6Ma.

  20. Can Morasko and Mundrabilla help Reconstructing Production Rates and Nuclear Reaction Cross-Sections for Light Cosmogenic Nuclides?

    NASA Astrophysics Data System (ADS)

    Merchel, S.; Smith, T.; Leya, I.; Pavetich, S.; Rugel, G.; Scharf, A.; Muszynski, A.

    2016-08-01

    Lighter nuclides of He, Ne, and Ar, and radionuclides Be-10, Al-26, Cl-36 and Ca-41 are measured in troilite, schreibersite and bulk metal of Mundrabilla and Morasko. Traces of S largely enhance Al-26 production. Cl-36-Ar-36 CRE ages are undisturbed.

  1. The tendency analytical equations of stable nuclides and the superluminal velocity motion laws of matter in geospace

    NASA Astrophysics Data System (ADS)

    Yan, Kun

    In this paper, by discussing the existent distribution trend of relation for the proton number and the neutron number to be included by the stable nuclides in geospace, the tendency analytical method and it's periodic distribution equation forms of the stable nuclides are expressed at first. Then the comparison result between the curve of the theoretical equation analysis and the points of the experimental distribution data of the stable nuclides in geospace are given. Further more, the stable nuclide limit and the chemical element limit for the chemical element periodic table are given, and the possible corresponding relation equation with the positron-particle annihilation is expressed, which includes the estimation of the order of the static mass to be situated nearby at the electron neutrino structural dimension. Subsequently, by forming two hypotheses about the energy state of vacuum matter, and basing on the equivalent Binet equation, the mass equations and the energy equations of the partial moving with light-velocity or superluminal-velocity motion fusing with the results of Einstein special relativity are expressed. As inference, the possible corresponding relations between the mass equations and energy equations with the dark matter and dark energy are discussed tentatively.

  2. Composites

    NASA Astrophysics Data System (ADS)

    Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-Nędza, A.; Mackiewicz, S.; Dutkiewicz, J.

    2014-11-01

    It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

  3. Use of the Riesz method to calculate axisymmetric vibrations of composite shells of revolution supported by rings and filled with a liquid

    NASA Astrophysics Data System (ADS)

    Grishanina, T. V.; Shklyarchuk, F. N.

    2016-05-01

    We consider the axisymmetric vibrations of a composite structure shaped as a system of thin shells of revolution connected by rings and filled with an ideal incompressible liquid. The structure is divided into independent shell blocks and frame rings. According to the Riesz method, the displacements of each free block treated as a momentless shell are represented as a series in prescribed functions supplemented with local functions of the shell boundary bending. According to the method of variations in displacements, the axisymmetric vibrations of a liquid in an elastic shell of revolution are described by plane displacement and deplanation of the liquid cross-sections. The plane displacement of the liquid is integrally expressed in terms of the shell normal displacements, and the deplanation is represented as a series in prescribed functions of the axial coordinate. The potential and kinetic energies of the system are first written in terms of generalized coordinates of independent free shell and frame blocks filled with the liquid and with free surfaces at the ends. Then the kinematic conditions of conjugation of the shell edges with the frame and the liquid surfaces are used to eliminate a part of generalized coordinates. Moreover, the generalized coordinates representing the deplanation of the liquid cross-sections in the cavities are also eliminated as cyclic coordinates. As a result, the potential and kinetic energies of the systemare written in terms of the basic generalized coordinates of the composite structure as a whole. As an example, the natural axisymmetric vibrations are calculated for a tank filled with a liquid, which consists of a cylindrical shell, spherical bottom shell, and the frame connecting these shells. The Riesz method convergence is estimated by the number of prescribed functions, as well as the influence of the deplanation of the liquid cross-sections and the shape of the transverse cross-section of the frame.

  4. Actinide nuclear data for reactor physics calculations

    SciTech Connect

    Brady, M.C.; Wright, R.Q. ); England, T.R. )

    1991-07-01

    Calculational methodologies and data sources used to predict and recommend fission-product yields and delayed neutron and prompt neutron data for a number of actinide nuclides are presented and discussed. This compilation of nuclear data is the result of a nearly three-year effort under the Japan/US Actinide Program (JUSAP) at Oak Ridge National Laboratory to provide nuclear data supporting the preliminary design of an actinide burner reactor. In this type of reactor, minor actinides are the major components of the fuel. Nuclear data for these minor actinides are, therefore, essential in the design of such reactors. Fission yield, delayed neutron, and prompt neutron data are presented in the report for the following nuclides: Neptumium-237, Plutonium-238, -240, and -242, Americium-241 and -243, and Curium-242, -243, -244, -246, and -248. Additionally, prompt neutron data are also presented for these nuclides (except Plutonium-240, -242 and Curium-242) and for Curium-245 and -247. As in all compilations of nuclear data, the information in this report is subject to change as newer data become available. Most of the data presented here are based on calculational methodologies and should be revised as experimental data become available. The release of Version 6 of the Evaluated Nuclear Data Files (ENDF/B-6) is expected to be completed in 1991 and should replace this evaluation in areas of overlap although no serious discrepancies are expected between this compilation and ENDF/B-6. Because of the large amount of data comprising this compilation and limitations in publishing such a voluminous report, a complete listing of the explicit data is not included in this report. The data are, however, available from the authors on 5 {1/2}-in. high-density (1.2-Mbyte) diskettes. The file contents and formats are described in the text, and examples are given in the appendices. 34 refs., 18 tabs.

  5. Determining Atomic-Scale Structure and Composition of Organo-Lead Halide Perovskites by Combining High-Resolution X-ray Absorption Spectroscopy and First-Principles Calculations

    DOE PAGES

    Drisdell, Walter S.; Leppert, Linn; Sutter-Fella, Carolin M.; ...

    2017-04-20

    In this paper, we combine high-energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy (XAS) measurements with first-principles density functional theory (DFT) calculations to provide a molecular-scale understanding of local structure, and its role in defining optoelectronic properties, in CH3NH3Pb(I1–xBrx)3 perovskites. The spectra probe a ligand field splitting in the unoccupied d states of the material, which lie well above the conduction band minimum and display high sensitivity to halide identity, Pb-halide bond length, and Pb-halide octahedral tilting, especially for apical halide sites. The spectra are also sensitive to the organic cation. We find that the halides in these mixed compositionsmore » are randomly distributed, rather than having preferred octahedral sites, and that thermal tilting motions dominate over any preferred structural distortions as a function of halide composition. Finally, these findings demonstrate the utility of the combined HERFD XAS and DFT approach for determining structural details in these materials and connecting them to optoelectronic properties observed by other characterization methods.« less

  6. Measuring the Noble Metal and Iodine Composition of Extracted Noble Metal Phase from Spent Nuclear Fuel Using Instrumental Neutron Activation Analysis

    SciTech Connect

    Palomares, R. I.; Dayman, Kenneth J.; Landsberger, Sheldon; Biegalski, Steven R.; Soderquist, Chuck Z.; Casella, Amanda J.; Brady Raap, Michaele C.; Schwantes, Jon M.

    2015-04-01

    Mass quantities of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis (NAA). Nuclide presence is predicted using fission yield analysis, and mass quantification is derived from standard gamma spectroscopy and radionuclide decay analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO2 fuel dissolved in nitric acid and UO2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. Lastly, the implications of the rapid analytic speed of instrumental NAA are discussed in relation to potential nuclear forensics applications.

  7. Cenozoic landscape evolution in Terra Nova Bay region: new evidence from multiple cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    di Nicola, L.; Baroni, C.; Strasky, S.; Salvatore, M. C.; Schlüchter, C.; Akçar, N.; Kubik, P.; Wieler, R.

    2009-04-01

    Geomorphological surveys and cosmogenic nuclide analysis allow us to reconstruct the chronology of pre- LGM variations of the East Antarctic Ice Sheet (EAIS) and valley glaciers. In the Terra Nova Bay region, relict glacial features, such as glacially-scoured mountain tops and erratic fields are well preserved. The combination of noble gas (21Ne), and radionuclides (10Be and 26Al) are well suited to unravel the chronology of these glacial landforms. Exposure ages based on 10Be, 26Al and 21Ne data from weathered bedrock from the highest rounded summits of the coastal area (Mt. Abbott, Mt. Keinath and Mt. Crummer) demonstrate that they have been free of ice since at least 6 Ma (Northern Foothills and Boomerang Glacier area) and 4 Ma (Larsen Glacier area). This implies that glacially-scoured coastal piedmonts represent relict features that have not been overridden by erosive ice since at least the Pliocene. A similar scenario can be deduced from an inland area (60 km from the coast), located at the margin of the polar plateau (Mt. Pollock and the Archaumbault Ridge). Our data set strongly indicates a continuous exposure history for the relict alpine morphology, which is shown to be older than 6 to 7.5 Ma. In addition, denudation rates inferred by our data show that erosion of granite summits has been negligible. Erosion rates, ranging from 11 to 24 cm/Myr in the coastal area and below 9 cm/Myr further inland, indicate long lasting cold and hyperarid climate conditions. The combination of stable and radionuclide isotopes document complex exposure histories of the glacial drifts preserved in the coastal area. They allow us to identify different glacial phases which cannot be documented by geomorphic and glacial geologic evidence alone. Erratic boulders from 390 to 675 m asl, which are below the rounded summits of the coastal pedimonts and above the late-Pleistocene glacial drift preserved up to 350 m asl, yield variable exposure ages of 90 to 700 ka. This documents

  8. The rapidly advancing field of applications of nuclides produced in terrestrial solids in earth and planetary sciences

    NASA Astrophysics Data System (ADS)

    Lal, D.

    2005-12-01

    The field of cosmogenic in situ nuclides in terrestrial solids is about 2 decades old, beginning with the realization that the commonly occurring mineral quartz allowed convenient study of in situ produced nuclides, 10Be and 26Al (Lal and Arnold, 1985; Nishiizumi et al., 1985)), which in turn provide estimates of cosmic ray irradiation history of quartz. Since then the field has continually developed, providing time scales in several disciplines of paleoclimatology, geomorphology, tectonics, meteorology, and volcanology. Realizing the importance of determining accurate time scales in earth sciences, several scientists joined in to implement a project: Cosmic-Ray-Originated Nuclide Systematics on Earth Project (CRONUS), for improving rates of production of cosmogenic nuclides in targets exposed to cosmic radiation under different conditions. These efforts will undoubtedly immensely increase the potentials of the cosmogenic in situ method. In modeling of the cosmogenic nuclide data, one generally faces a dilemma in most cases, namely that one does not have sufficient amount of useful geological data about the samples under study. For instance, one of the principal obstacles constraining exposure histories is the information on its erosion and exfoliation history during exposure. A new approach is feasible to tackle the above mentioned shortcoming utilizing the unique feature of the cosmogenic interaction, namely that the cosmic ray flux at a given point within an object depends on the angular distribution of path lengths of cosmic ray particles arriving at the point from different directions. Interestingly, this distribution continuously changes as the surface of the object evolves with erosion and/or exfoliation. Herein lies the potential of determining both the exposure history and the evolutionary history of the solid object under investigation from multiple determinations of nuclide concentration at different points within a target. We present as examples

  9. Erosion of mountain plateaus along Sognefjord, Norway, constrained by cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    Andersen, Jane Lund; Egholm, David L.; Knudsen, Mads F.; Linge, Henriette; Jansen, John D.

    2016-04-01

    Norway is famous for its deeply incised, steep-sided fjords, carved out by glacial erosion. The high relief of the fjords stands in contrast to the extensive areas of relatively low relief found between the fjords. The origin and development of these low-relief areas remain debated. The classical interpretation relates them to a Mesozoic peneplanation surface, uplifted to the current high elevation in the early Cenozoic (e.g. Nesje, 1994). The validity of this interpretation has, however, been repeatedly questioned in recent times (e.g. Nielsen et al. 2009, Steer et al. 2012). Recent studies point instead to a significant impact of glacial and periglacial erosion processes on the long-term development of the low-relief surfaces (Egholm et al. 2015). Here, we present a large new dataset of in-situ produced cosmogenic 10Be and 26Al in bedrock and boulders from the high, flat summit surfaces along a transect from the coast to the inner parts of Sognefjorden in Norway. Our results indicate substantial glacial modification of the sampled low-relief surfaces within the last 50 ka. Close to the coast, at an elevation of around 700 meters, the cosmogenic nuclide signal was reset around the Younger Dryas due to extensive glacial erosion. Regarding the higher surfaces further inland, our results indicate a maximum cosmogenic nuclide inheritance of 20-30 ka prior to the last deglaciation. We do not find any signs of exceptional longevity of the low-relief landscape. In contrast, our results indicate that the low-relief areas were continuously eroded by glacial and periglacial processes in the Quaternary. Nesje & Whillans. Erosion of Sognefjord, Norway. Geomorphology 9(1), 33-45, 1994. Nielsen et al. The evolution of western Scandinavian topography: a review of Neogene uplift versus the ICE (isostasy-climate-erosion) hypothesis. Journal of Geodynamics 47(2), 72-95, 2009. Steer et al. Bimodal Plio-Quaternary glacial erosion of fjords and low-relief surfaces in Scandinavia

  10. Incision of the Yangtze River at the First Bend Determined by Three-Nuclide Burial Dating

    NASA Astrophysics Data System (ADS)

    McPhillips, D. F.; Hoke, G. D.; Rood, D. H.; Bierman, P. R.

    2015-12-01

    On the southeast margin of the Tibetan Plateau, the evolution of the Yangtze River and its major tributaries has become an important source of data for investigating geodynamics. In particular, the timing of river incision is frequently interpreted as a proxy for the timing of surface uplift in the absence of structural evidence. We investigate the timing of the incision of the gorge at the First Bend using cosmogenic nuclide burial dating of coarse, quartz sediments from caves. Sediments were deposited when the caves were near river level and subsequently abandoned as the river incised. To resolve burial ages >5 Ma, we measured the radionuclides 10Be and 26Al, and the stable nuclide 21Ne. Results from 4 caves show that 26Al and 10Be concentrations are an order of magnitude lower in abandoned cave samples than in a river-level cave sample where deposition is active (10Be: 1.3x104 and 3.4x105 at/g). In contrast, 26Al/10Be ratios in all caves are ≥6.2 and indistinguishable within error. 21Ne concentrations range from 2.1x106 to 7.8x106 at/g. The results are consistent with an old age for the abandoned cave deposits, such that most of the radionuclides initially present have decayed and the concentrations that we measure today are the result of millions of years of exposure to muons. We solve for burial ages, taking into account in situ muogenic production, and find that the majority of the gorge (1 km) was likely incised between ~12 and 9 Ma. The results also require that the rate of river incision declined after the gorge was cut below the lowest elevation cave at 9 Ma. Inverse modeling of published low-temperature thermochronology (Ouimet et al., 2010) supports our burial age results. River capture near the First Bend, which likely integrated the modern Yangtze, likely occurred prior to the mid-Miocene incision of the gorge. In view of the geographic position of the First Bend—just downslope from the southeast margin of the Plateau—it is difficult to explain

  11. Timing of European fluvial terrace formation and incision rates constrained by cosmogenic nuclide dating

    NASA Astrophysics Data System (ADS)

    Schaller, Mirjam; Ehlers, Todd A.; Stor, Tomas; Torrent, Jose; Lobato, Leonardo; Christl, Marcus; Vockenhuber, Christof

    2016-10-01

    Age constraints of late Cenozoic fluvial terraces are important for addressing surface process questions related to the incision rates of rivers, or tectonic and climate controls on denudation and sedimentation. Unfortunately, absolute age constraints of fluvial terraces are not always possible, and many previous studies have often dated terraces with relative age constraints that do not allow for robust interpretations of incision rates and timing of terrace formation. However, in situ-produced cosmogenic nuclides allow absolute age determination, and hence incision rates, of fluvial deposits back to 5 Ma. Here we present, cosmogenic depth profile dating and isochron burial dating of four different river systems in Europe spanning 12° of latitude. We do this to determine river incision rates and spatial variations in the timing of terrace formation. Isochron burial age constraints of four selected terraces from the Vltava river (Czech Republic) range between 1.00 ± 0.21 to 1.99 ± 0.45Ma. An isochron burial age derived for the Allier river (Central France) is 2.00 ± 0.17Ma. Five terrace levels from the Esla river (NW Spain) were dated between 0.08 + 0.04 / - 0.01Ma and 0.59 + 0.13 / - 0.20Ma with depth profile dating. The latter age agrees with an isochron burial age of 0.52 ± 0.20Ma. Two terrace levels from the Guadalquivir river (SW Spain) were dated by depth profile dating to 0.09 + 0.03 / - 0.02Ma and 0.09 + 0.04 / - 0.03Ma. The one terrace level from the Guadalquivir river dated by isochron burial dating resulted in an age of 1.79 ± 0.18Ma. Results indicate that the cosmogenic nuclide-based ages are generally older than ages derived from previous relative age constraints leading to a factor 2-3 lower incision rates than previous work. Furthermore, the timing of terrace formation over this latitudinal range is somewhat obscured by uncertainties associated with dating older terraces and not clearly synchronous with global climate variations.

  12. U-series nuclides migration from the vadose zone to a chalk aquifer

    NASA Astrophysics Data System (ADS)

    Hubert, A.; Bourdon, B.; Pili, E.

    2003-04-01

    We have studied the uranium-series disequilibria in chalk aquifer and the vadose zone above it in order to characterise the time scales of radionuclides migration from the water recharge zone of the aquifer to the river. Our field area is located in Champagne (France). The aquifer is characterized by a double porosity: matrix and fracture, providing both a fast and a slow pathways for water flow. We have collected both carbonate rocks and groundwater samples from boreholes and spring and river water from the same area. The boreholes have been drilled along a flow line. Rock/water interaction inside the aquifer induces dissolution and reprecipitation of carbonates, together with a mobilisation of uranium, and additionally the decay of radionuclides results in a-recoil effect particularly for the 234U--238U pair. We have measured uranium and thorium isotopes for carbonates samples from the aquifer by TIMS and multi-collection ICP-MS. The fractionation of uranium and thorium nuclides is distinctive in the various parts of the aquifer. Rock samples from the saturated zone show a depletion in 234U with a (234U/238U) ratio ranging from 0.945 to 0.993 (± 0.005). This indicates that uranium 234U has been released by rock/water interaction over the last million year. Nevertheless, rock samples from the vadose zone display an activity ratio 234U/238U above 1 and range from 1.002 to 1.052 (± 0.005), suggesting uranium reprecipitation possibly by a redox front. (230Th/238U) ratio range from 1.25 to 1.59 (± 0.03) in both saturated and vadose zone, whilst (230Th/232Th) ratio vary from 1.89 to 5.68 (± 0.05) with the highest values for the vadose zone. The 234U--230Th system shows a significant mobility of uranium less than 300 000 years ago within the aquifer. We are curently analysing water samples which will provide us further insights on the migration timescale of uranium-series nuclides in groundwater and will document the processes of groundwater/carbonate interaction.

  13. Dating the incision of the Yangtze River gorge at the First Bend using three-nuclide burial ages

    NASA Astrophysics Data System (ADS)

    McPhillips, Devin; Hoke, Gregory D.; Liu-Zeng, Jing; Bierman, Paul R.; Rood, Dylan H.; Niedermann, Samuel

    2016-01-01

    Incision of the Yangtze River gorge is widely interpreted as evidence for lower crustal flow beneath the southeast margin of the Tibetan Plateau. Previous work focused on the onset of incision, but the duration of incision remains unknown. Here we present cosmogenic nuclide burial ages of sediments collected from caves on the walls of the gorge that show the gorge was incised ~1 km sometime between 18 and 9 Ma. Thereafter, incision slowed substantially. We resolve middle Miocene burial ages by using three nuclides and accounting for in situ muogenic production. This approach explains the absolute concentrations of 10Be, 26Al, and 21Ne, as well as 26Al/10Be and 21Ne/10Be ratios. A declining incision rate challenges existing geodynamic interpretations by suggesting that either (1) surface uplift has ceased immediately south of the plateau margin or (2) gorge incision is not a useful proxy for the timing of surface uplift.

  14. Cosmogenic nuclides in core samples of the Chico L6 chondrite - Evidence for irradiation under high shielding

    NASA Technical Reports Server (NTRS)

    Garrison, D. H.; Bogard, D. D.; Albrecht, A. A.; Vogt, S.; Herzog, G. F.; Klein, J.; Fink, D.; Dezfouly-Arjomandy, B.; Middleton, R.

    1992-01-01

    Results are presented from an analysis of core samples obtained from different depths of the Chico (New Mexico) L6 chondrite for various cosmogenic nuclides (Be-10, Al-26, and stable isotopes of He, Ne, and Ar). The relationships between the measured abundances of cosmogenic nuclides and cosmogenic Ne-22/Ne-21 ratio were compared with predictions of recent semiempirical models of Graf et al. (1990) and Reedy (1991), and it was found that both models closely reproduce the observed trends and absolute values of the data obtained. Noble gas data indicate that Chico experienced shielding similar to that of Jilin and greater than those of the Knyahinya or the Keyes chondrites. The exposure history for Chico is discussed.

  15. First Use of High Charge States for Mass Measurements of Short-Lived Nuclides in a Penning Trap

    SciTech Connect

    Ettenauer, S.; Gallant, A. T.; Dilling, J.; Simon, M. C.; Chaudhuri, A.; Mane, E.; Delheij, P.; Pearson, M. R.; Brunner, T.; Chowdhury, U.; Simon, V. V.; Brodeur, M.; Andreoiu, C.; Audi, G.; Lopez-Urrutia, J. R. Crespo; Ullrich, J.; Gwinner, G.; Lapierre, A.; Lunney, D.; Ringle, R.

    2011-12-30

    Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed {beta} emitter {sup 74}Rb (T{sub 1/2}=65 ms). The determination of its atomic mass and an improved Q{sub EC} value are presented.

  16. Cosmogenic nuclides in core samples of the Chico L6 chondrite - Evidence for irradiation under high shielding

    NASA Technical Reports Server (NTRS)

    Garrison, D. H.; Bogard, D. D.; Albrecht, A. A.; Vogt, S.; Herzog, G. F.; Klein, J.; Fink, D.; Dezfouly-Arjomandy, B.; Middleton, R.

    1992-01-01

    Results are presented from an analysis of core samples obtained from different depths of the Chico (New Mexico) L6 chondrite for various cosmogenic nuclides (Be-10, Al-26, and stable isotopes of He, Ne, and Ar). The relationships between the measured abundances of cosmogenic nuclides and cosmogenic Ne-22/Ne-21 ratio were compared with predictions of recent semiempirical models of Graf et al. (1990) and Reedy (1991), and it was found that both models closely reproduce the observed trends and absolute values of the data obtained. Noble gas data indicate that Chico experienced shielding similar to that of Jilin and greater than those of the Knyahinya or the Keyes chondrites. The exposure history for Chico is discussed.

  17. A multi-layered active target for the study of neutron-unbound nuclides at NSCL

    NASA Astrophysics Data System (ADS)

    Freeman, Jessica; Gueye, Paul; Redpath, Thomas; MoNA Collaboration

    2017-01-01

    The characteristics of neutron-unbound nuclides were investigated using a multi-layered Si/Be active target designed for use with the MoNA/LISA setup at the National Superconducting Cyclotron (NSCL). The setup consists of the MoNA/LISA arrays (for neutron detection) and a superconducting sweeper magnet (for charged separation) to identify products following the decay of neutron unbound states. The segmented target consisted of three 700 mg/cm2 beryllium targets and four 0.14 mm thick 62x62 mm2 silicon detectors. As a commissioning experiment for the target the decay of two-neutron unbound 26O populated in a one-proton removal reaction from a radioactive 27F beam was performed. The 27F secondary radioactive beam from the NSCL's Coupled Cyclotron Facility was produced from the fragmentation of a 140 MeV/u 48Ca beam incident on a thick beryllium target and then cleanly selected by the A1900 fragment separator. The energy loss and position spectra of the incoming beam and reaction products were used to calibrate the Silicon detectors to within 1.5% in both energy and position. A dedicated Geant4 model of the target was developed to simulate the energy loss within the target. A description of the experimental setup, simulation work, and energy and position calibration will be presented. DoE/NNSA - DE-NA0000979.

  18. Activity concentration of natural radioactive nuclides in nonmetallic industrial raw materials in Japan.

    PubMed

    Iwaoka, Kazuki; Tabe, Hiroyuki; Yonehara, Hidenori

    2014-11-01

    Natural materials such as rock, ore, and clay, containing natural radioactive nuclides are widely used as industrial raw materials in Japan. If these are high concentrations, the workers who handle the material can be unknowingly exposed to radiation at a high level. In this study, about 80 nonmetallic natural materials frequently used as industrial raw materials in Japan were comprehensively collected from several industrial companies, and the activity concentrations of (238)U series, (232)Th series and (40)K in the materials was determined by ICP-MS (inductively-coupled plasma mass spectrometer) and gamma ray spectrum analyses. Effective doses to workers handling them were estimated by using methods for dose estimation given in the RP 122. We found the activity concentrations to be lower than the critical values defined by regulatory requirements as described in the IAEA Safety Guide. The maximum estimated effective dose to workers handling these materials was 0.16 mSv y(-1), which was lower than the reference level (1-20 mSv y(-1)) for existing situation given in the ICRP Publ.103.

  19. Studies of Itokawa's Surface Exposure by Measurements of Cosmic-ray Produced Nuclides

    NASA Technical Reports Server (NTRS)

    Caffee, M. W.; Nishiizumi, K.; Tsuchiyama, A.; Uesugi, M.; Zolensky, M. E.

    2014-01-01

    We plan to investigate the evolutionary history of surface materials from 25143 Itokawa, the Hayabusa samples. Our studies are based on the measurement of nuclides produced in asteroidal surface materials by cosmic rays. Cosmogenic radionuclides are used to determine the duration and nature of the exposure of materials to energetic particles. Our goals are to understand both the fundamental processes on the asteroidal surface and the evolutionary history of its surface materials. They are also key to understanding the history of Itokawa's surface and asteroid-meteoroid evolutionary dynamics. To achieve our key goals, in particular reconstructing the evolutionary histories of the asteroidal surface, we proposed: (1) characterizing Itokawa particles using SXCT, SXRD, and FE-SEM without modification of the sample; (2) embedding each particle in acrylic resin, then slicing a small corner with an ultra-microtome and examining it using super-STEM and SIMS for characterizing surface morphology, space weathering, and oxygen three-isotope analysis; and finally (3) measuring small amounts of cosmogenic radionuclides (104-105 atoms) in Hayabusa samples by AMS. However, we have to modify our plan due to unexpected situation.

  20. Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad.

    PubMed

    Lebatard, Anne-Elisabeth; Bourlès, Didier L; Duringer, Philippe; Jolivet, Marc; Braucher, Régis; Carcaillet, Julien; Schuster, Mathieu; Arnaud, Nicolas; Monié, Patrick; Lihoreau, Fabrice; Likius, Andossa; Mackaye, Hassan Taisso; Vignaud, Patrick; Brunet, Michel

    2008-03-04

    Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16 degrees 00'N, 18 degrees 53'E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16 degrees 15'N, 17 degrees 29'E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronological estimation of the hominid remains: early Pliocene (3-3.5 Ma) at KT 12 and late Miocene ( approximately 7 Ma) at TM 266. Atmospheric (10)Be, a cosmogenic nuclide, was used to quasicontinuously date these sedimentary units. The authigenic (10)Be/(9)Be dating of a pelite relic within the sedimentary level containing Abel yields an age of 3.58 +/- 0.27 Ma that points to the contemporaneity of Australopithecus bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 (10)Be/(9)Be ages obtained within the anthracotheriid unit containing Toumaï bracket, by absolute dating, the age of Sahelanthropus tchadensis to lie between 6.8 and 7.2 Ma. This chronological constraint is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock.

  1. Applications of in situ cosmogenic nuclides in the geologic site characterization of Yucca Mountain, Nevada

    SciTech Connect

    Gosse, J.C.; Harrington, C.D.; Whitney, J.W.

    1996-08-01

    The gradual buildup of rare isotopes from interactions between cosmic rays and atoms in an exposed rock provides a new method of directly determining the exposure age of rock surfaces. The cosmogenic nuclide method can also provide constraints on erosion rates and the length of time surface exposure was interrupted by burial. Numerous successful applications of the technique have been imperative to the complete surface geologic characterization of Yucca Mountain, Nevada, a potential high level nuclear waste repository. The {sup 10}Be exposure age of Black Cone lava, within a ten mile radius of the proposed repository site, is 840 {+-} 210 kyr (in agreement with previous K/Ar dates of 1.0 {+-} 0.1 Ma). Rates of erosion of the tuff bedrock (< 0.4 cm/kyr from 7 {sup 10}Be measurements) and of hillslope colluvium ({approximately} 0.5 cm/kyr from {sup 10}Be dates on boulder deposits) preclude denudation of the mountain as a concern. Neotectonic concerns (rate of slip and timing of last significant movement along faults) are also being addressed with in situ {sup 14}C and {sup 10}Be measurements on scarp surfaces and on fault-dissected landforms where no surficial expression of the fault is preserved.

  2. Development of the sampling and nuclide analysis methods for spent HEPA filter wastes

    SciTech Connect

    Young-Yong Ji; Dae Seok Hong; Il-Sik Kang; Bum-Kyoung Seo; Jong-Sik Shon

    2007-07-01

    Spent filter wastes of about 2,160 units have been stored in the waste storage facility of the Korea Atomic Energy Research Institute since its operation. These spent filters have generally consisted of a HEPA filter after its filtering of all the contaminants in the gas stream generated during the operation of the HANARO research reactor and the nuclear fuel cycle facilities. At the moment, to secure enough storage space, it is necessary to make a volume reduction of the stored radioactive wastes through a compression treatment or a regulatory clearance. There have been many studies on a treatment and a clearance of the low level radioactive wastes generated from nuclear facilities. These methods are used in view of a reduction of a management cost and disposal cost and the security of free space for a waste storage facility approaching saturation. In order to dispose of the spent filters, it is first necessary to conduct a radionuclide assessment of them. To do that, a sampling procedure should be prepared to obtain a representative sample from a spent filter. As for conducting a nuclide analysis for this representative sample, a corresponding spent filter can be determined as either a regulatory clearance waste or a radioactive waste. (authors)

  3. Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad

    PubMed Central

    Lebatard, Anne-Elisabeth; Bourlès, Didier L.; Duringer, Philippe; Jolivet, Marc; Braucher, Régis; Carcaillet, Julien; Schuster, Mathieu; Arnaud, Nicolas; Monié, Patrick; Lihoreau, Fabrice; Likius, Andossa; Mackaye, Hassan Taisso; Vignaud, Patrick; Brunet, Michel

    2008-01-01

    Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16°00′N, 18°53′E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15′N, 17°29′E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronological estimation of the hominid remains: early Pliocene (3–3.5 Ma) at KT 12 and late Miocene (≈7 Ma) at TM 266. Atmospheric 10Be, a cosmogenic nuclide, was used to quasicontinuously date these sedimentary units. The authigenic 10Be/9Be dating of a pelite relic within the sedimentary level containing Abel yields an age of 3.58 ± 0.27 Ma that points to the contemporaneity of Australopithecus bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 10Be/9Be ages obtained within the anthracotheriid unit containing Toumaï bracket, by absolute dating, the age of Sahelanthropus tchadensis to lie between 6.8 and 7.2 Ma. This chronological constraint is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock. PMID:18305174

  4. CRONUS-EU Cosmic Ray Produced Nuclide Systematics - The European Contribution

    NASA Astrophysics Data System (ADS)

    Dunai, T. J.; Benedetti, L.; van der Borg, K.; von Blanckenburg, F.; Ivy-Ochs, S.; Korschinek, G.; Masarik, J.; Niedermann, S.; Pik, R.; Stuart, F.; Wieler, R.; Wijbrans, J.

    2005-12-01

    The main objective of the CRONUS-EU is to advance Terrestrial cosmogenic nuclide (TCN) techniques into a robust tool for Earth surface and environmental sciences. CRONUS-EU aims to achieve this goal via: (1) High quality calibration of TCN production rates at independently dated surfaces (2) High quality calibration of TCN production rates using artificial targets (3) Systematic cross calibration of production rates of different TCNs (4) Refinement of scaling factors that describe the spatial and temporal variation of the cosmic ray flux relevant for TCN production using calibration measurements and numerical modeling from physical principles (5) Reducing the uncertainty of decay constants (6) Establishing the use of additional mineral phases in exposure age dating (7) Improvement and standardization of chemical routines (8) Laboratory cross calibrations (9) Training of young researchers and the user community The effort necessary to achieve above goal is significant even for the strong network teams in CRONUS-EU. To strengthen our effort and to achieve international evaluation and acceptance, we are seeking close collaboration with CRONUS-Earth, the parallel-running northern American sister initiative that obtained funding through NSF. Formal links between the two initiatives are established and each consortium will address complementary aspects to achieve the common goal. CRONUS-EU is a Marie-Curie Research and Training program, supported by the European Community's Program: Improving the Human Research Potential and the Socio-economic Knowledge base. www.cronus-eu.net

  5. Dual-Nuclide Radiopharmaceuticals for Positron Emission Tomography Based Dosimetry in Radiotherapy.

    PubMed

    Wurzer, Alexander; Seidl, Christof; Morgenstern, Alfred; Bruchertseifer, Frank; Schwaiger, Markus; Wester, Hans-Jürgen; Notni, Johannes

    2017-08-21

    Improvement of the accuracy of dosimetry in radionuclide therapy has the potential to increase patient safety and therapeutic outcomes. Although positron emission tomography (PET) is ideally suited for acquisition of dosimetric data because PET is inherently quantitative and offers high sensitivity and spatial resolution, it is not directly applicable for this purpose because common therapeutic radionuclides lack the necessary positron emission. This work reports on the synthesis of dual-nuclide labeled radiopharmaceuticals with therapeutic and PET functionality, which are based on common and widely available metal radionuclides. Dual-chelator conjugates, featuring interlinked cyclen- and triazacyclononane-based polyphosphinates DOTPI and TRAP, allow for strictly regioselective complexation of therapeutic (e.g., (177) Lu, (90) Y, or (213) Bi) and PET (e.g., (68) Ga) radiometals in the same molecular framework by exploiting the orthogonal metal ion selectivity of these chelators (DOTPI: large cations, such as lanthanide(III) ions; TRAP: small trivalent ions, such as Ga(III) ). Such DOTPI-TRAP conjugates were decorated with 3 Gly-urea-Lys (KuE) motifs for targeting prostate-specific membrane antigen (PSMA), employing Cu-catalyzed (CuAAC) as well as strain-promoted (SPAAC) click chemistry. These were labeled with (177) Lu or (213) Bi and (68) Ga and used for in vivo imaging of LNCaP (human prostate carcinoma) tumor xenografts in SCID mice by PET, thus proving practical applicability of the concept. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Glass Fiber Post/Composite Core Systems Bonded to Human Dentin: Analysis of Tensile Load vs Calculated Tensile Strength of Various Systems Using Pull-out Tests.

    PubMed

    Keul, Christine; Köhler, Patrick; Hampe, Rüdiger; Roos, Malgorzata; Stawarczyk, Bogna

    Pull-out testing was used to determine the tensile load (TL) and tensile strength (TS) of five different fiber post systems bonded to human intracanal dentin. 120 caries-free premolars, canines, and maxillary central incisors were divided into 5 different groups for 5 fiber post systems (n = 24): 1. RelyX Fiber Post 3D (RX3D); 2. RelyX Fiber Post (RX); 3. Luxa- Post (LP); 4. FibreKleer 4X Tapered Post (FK); 5. ParaPost Taper Lux (PP). The teeth were prepared and posts inserted. Core buildups were performed with the corresponding product's resin composite. All specimens were stored in water for 24 h at 37°C. TL and TS were tested on half of the specimens (n = 12/group). The remaining samples were thermocycled (10,000 x 5°C/55°C) before testing. TL was directly measured and TS was calculated using the bonding surface. Failure modes were identified using a stereomicroscope. Data were analyzed using twoway ANOVA with the post-hoc Scheffé test, as well as the chi-squared test (p < 0.05). FK and LP resulted in the lowest mean TL but were not significantly different from those of RX and RX3D. The highest mean TL and TS were observed for PP. Nevertheless, PP fell within the same statistical subset as RX3D and RX. Thermocycling showed no impact on the results. RX3D predominantly showed debonding of the post plus core buildup from the tooth; all other systems mainly demonstrated detachment of the core from the posts. PP, RX, and RX3D together with an adhesive core buildup yielded the highest bond strength to human dentin. Parameters TL and TS showed the same tendencies and statistical evidence.

  7. Reevaluation of the average prompt neutron emission multiplicity (nubar) values from fission of uranium and transuranium nuclides

    SciTech Connect

    Holden, N.E.; Zucker, M.S.

    1984-01-01

    In response to a need of the safeguards community, we have begun an evaluation effort to upgrade the recommended values of the prompt neutron emission multiplicity distribution, P/sub nu/ and its average value, nubar. This paper will report on progress achieved thus far. The evaluation of the uranium, plutonium, americium and curium nuclide's nubar values will be presented. The recommended values will be given and discussed. 61 references.

  8. Instrumental activation analysis of coal and fly ash with thermal and epithermal neutrons and short-lived nuclides

    USGS Publications Warehouse

    Steinnes, E.; Rowe, J.J.

    1976-01-01

    Instrumental neutron activation analysis is applied to the determination of about 25 elements in coals and fly ash by means of nuclides with half-lives of less than 48 h ; thermal and epithermal irradiations are used. The results indicate that epithermal activation is preferable for twelve of the elements (Ga, As, Br, Sr, In, Cs, Ba, La, Sm, Ho, W and U). Data for SRM 1632 (coal) and SRM 1633 (fly ash) compare favorably with the results obtained by other investigators. ?? 1976.

  9. Detailed Burnup Calculations for Testing Nuclear Data

    SciTech Connect

    Leszczynski, F.

    2005-05-24

    A general method (MCQ) has been developed by introducing a microscopic burnup scheme that uses the Monte Carlo calculated fluxes and microscopic reaction rates of a complex system and a depletion code for burnup calculations as a basis for solving nuclide material balance equations for each spatial region in which the system is divided. Continuous energy-dependent cross-section libraries and full 3D geometry of the system can be input for the calculations. The resulting predictions for the system at successive burnup time steps are thus based on a calculation route where both geometry and cross sections are accurately represented, without geometry simplifications and with continuous energy data, providing an independent approach for benchmarking other methods and nuclear data of actinides, fission products, and other burnable absorbers. The main advantage of this method over the classical deterministic methods currently used is that the MCQ System is a direct 3D method without the limitations and errors introduced on the homogenization of geometry and condensation of energy of deterministic methods. The Monte Carlo and burnup codes adopted until now are the widely used MCNP and ORIGEN codes, but other codes can be used also. For using this method, there is need of a well-known set of nuclear data for isotopes involved in burnup chains, including burnable poisons, fission products, and actinides. For fixing the data to be included in this set, a study of the present status of nuclear data is performed, as part of the development of the MCQ method. This study begins with a review of the available cross-section data of isotopes involved in burnup chains for power and research nuclear reactors. The main data needs for burnup calculations are neutron cross sections, decay constants, branching ratios, fission energy, and yields. The present work includes results of selected experimental benchmarks and conclusions about the sensitivity of different sets of cross

  10. Detailed Burnup Calculations for Testing Nuclear Data

    NASA Astrophysics Data System (ADS)

    Leszczynski, F.

    2005-05-01

    A general method (MCQ) has been developed by introducing a microscopic burnup scheme that uses the Monte Carlo calculated fluxes and microscopic reaction rates of a complex system and a depletion code for burnup calculations as a basis for solving nuclide material balance equations for each spatial region in which the system is divided. Continuous energy-dependent cross-section libraries and full 3D geometry of the system can be input for the calculations. The resulting predictions for the system at successive burnup time steps are thus based on a calculation route where both geometry and cross sections are accurately represented, without geometry simplifications and with continuous energy data, providing an independent approach for benchmarking other methods and nuclear data of actinides, fission products, and other burnable absorbers. The main advantage of this method over the classical deterministic methods currently used is that the MCQ System is a direct 3D method without the limitations and errors introduced on the homogenization of geometry and condensation of energy of deterministic methods. The Monte Carlo and burnup codes adopted until now are the widely used MCNP and ORIGEN codes, but other codes can be used also. For using this method, there is need of a well-known set of nuclear data for isotopes involved in burnup chains, including burnable poisons, fission products, and actinides. For fixing the data to be included in this set, a study of the present status of nuclear data is performed, as part of the development of the MCQ method. This study begins with a review of the available cross-section data of isotopes involved in burnup chains for power and research nuclear reactors. The main data needs for burnup calculations are neutron cross sections, decay constants, branching ratios, fission energy, and yields. The present work includes results of selected experimental benchmarks and conclusions about the sensitivity of different sets of cross

  11. VRF ("Visual RobFit") — nuclear spectral analysis with non-linear full-spectrum nuclide shape fitting

    NASA Astrophysics Data System (ADS)

    Lasche, George; Coldwell, Robert; Metzger, Robert

    2017-09-01

    A new application (known as "VRF", or "Visual RobFit") for analysis of high-resolution gamma-ray spectra has been developed using non-linear fitting techniques to fit full-spectrum nuclide shapes. In contrast to conventional methods based on the results of an initial peak-search, the VRF analysis method forms, at each of many automated iterations, a spectrum-wide shape for each nuclide and, also at each iteration, it adjusts the activities of each nuclide, as well as user-enabled parameters of energy calibration, attenuation by up to three intervening or self-absorbing materials, peak width as a function of energy, full-energy peak efficiency, and coincidence summing until no better fit to the data can be obtained. This approach, which employs a new and significantly advanced underlying fitting engine especially adapted to nuclear spectra, allows identification of minor peaks that are masked by larger, overlapping peaks that would not otherwise be possible. The application and method are briefly described and two examples are presented.

  12. High resolution and continuous reconstruction of Blake and Post Blake excursions using cosmogenic radio nuclides in the Antarctic ice core

    NASA Astrophysics Data System (ADS)

    Yokoyama, Y.; Tsunekawa, R.; Takahashi, S.; Miyairi, Y.; Aze, T.; Horiuchi, K.; Matsuzaki, H.; Motoyama, H.

    2015-12-01

    Geomagnetic excursions provide information on field mechanics and serve as a chronostratigraphic tool. Interpretation of sedimentological paleointensity records is complicated, and volcanic rocks provide only non-continuous records. Another means for reconstructing paleomagnetic intensity is analyzing cosmogenic radio nuclides. In this study, we reconstruct the Blake and the Post-Blake Excursions using the cosmogenic radio nuclide 10Be in the Dome Fuji ice core. It has been reported that the Blake Excursion and the Post-Blake Excursion occurred within the Brunhes Chron, at around 115 ka and 100 ka, respectively. These two excursions occurred in quick succession. The Post-Blake Excursion is relatively poorly studied, only being reconstructed from sediments and volcanic rocks. Results indicate there is a significant peaks in 10Be flux that is thought to be reflect respectively the Blake and the Post-Blake Excursions. The maximum 10Be flux during the Post-Blake Excurison is similar to that of the Blake Excursion, suggesting that the geomagnetic dipole field during the Post-Blake Excursion weakened by the same amount as during the Blake Excursion. We also compare the results for the Laschamp Excursion that we also reconstructed from the same ice core to discuss the nature of individual excursions inferred from the cosmogenic radio nuclides data.

  13. Measurements of cross sections for production of light nuclides by 120 GeV proton bombardment of Ni and Au

    NASA Astrophysics Data System (ADS)

    Okumura, Shintaro; Sekimoto, Shun; Yashima, Hiroshi; Matsushi, Yuki; Matsuzaki, Hiroyuki; Shibata, Seiichi; Ohtsuki, Tsutomu

    2014-09-01

    Production cross sections for long-lived cosmogenic nuclides, such as Be-10 and Al-26 have a very practical benefit for health and safety in radiation protection; they serve as a comprehensive nuclear database that can be used to estimate residual radioactivities in accelerator facilities. Cross sections are also indispensable for studying the specific formation mechanisms of these nuclides, where spallation, fission, or fragmentation is a dominant process. The fragmentation process is usually studied by production cross sections of light nuclides which are best measured by AMS. For energies above 100 MeV few measurements have been made and published. We have measured and report the first Be-10 and Al-26 production cross sections from Ni and Au produced by 120 GeV protons. The proton irradiation at 120 GeV was performed at Fermi National Accelerator Laboratory. The AMS measurements were performed at MALT, University of Tokyo. We will discuss the production mechanism of Be-10 and Al-26 by spallation and fragmentation.

  14. Iodine intake by adult residents of a farming area in Iwate Prefecture, Japan, and the accuracy of estimated iodine intake calculated using the Standard Tables of Food Composition in Japan.

    PubMed

    Nakatsuka, Haruo; Chiba, Keiko; Watanabe, Takao; Sawatari, Hideyuki; Seki, Takako

    2016-11-01

    Iodine intake by adults in farming districts in Northeastern Japan was evaluated by two methods: (1) government-approved food composition tables based calculation and (2) instrumental measurement. The correlation between these two values and a regression model for the calibration of calculated values was presented. Iodine intake was calculated, using the values in the Japan Standard Tables of Food Composition (FCT), through the analysis of duplicate samples of complete 24-h food consumption for 90 adult subjects. In cases where the value for iodine content was not available in the FCT, it was assumed to be zero for that food item (calculated values). Iodine content was also measured by ICP-MS (measured values). Calculated and measured values rendered geometric means (GM) of 336 and 279 μg/day, respectively. There was no statistically significant (p > 0.05) difference between calculated and measured values. The correlation coefficient was 0.646 (p < 0.05). With this high correlation coefficient, a simple regression line can be applied to estimate measured value from calculated value. A survey of the literature suggests that the values in this study were similar to values that have been reported to date for Japan, and higher than those for other countries in Asia. Iodine intake of Japanese adults was 336 μg/day (GM, calculated) and 279 μg/day (GM, measured). Both values correlated so well, with a correlation coefficient of 0.646, that a regression model (Y = 130.8 + 1.9479X, where X and Y are measured and calculated values, respectively) could be used to calibrate calculated values.

  15. High-precision Penning trap mass measurements of 9,10Be and the one-neutron halo nuclide 11Be

    NASA Astrophysics Data System (ADS)

    Ringle, R.; Brodeur, M.; Brunner, T.; Ettenauer, S.; Smith, M.; Lapierre, A.; Ryjkov, V. L.; Delheij, P.; Drake, G. W. F.; Lassen, J.; Lunney, D.; Dilling, J.

    2009-05-01

    Penning trap mass measurements of 9Be, 10Be (t1 / 2 = 1.51 My), and the one-neutron halo nuclide 11Be (t1 / 2 = 13.8 s) have been performed using TITAN at TRIUMF. The resulting 11Be mass excess (ME = 20 177.60 (58) keV) is in agreement with the current Atomic Mass Evaluation (AME03) [G. Audi, et al., Nucl. Phys. A 729 (2003) 337] value, but is over an order of magnitude more precise. The precision of the mass values of 9,10Be have been improved by about a factor of four and reveal a ≈ 2 σ deviation from the AME mass values. Results of new atomic physics calculations are presented for the isotope shift of 11Be relative to 9Be, and it is shown that the new mass values essentially remove atomic mass uncertainties as a contributing factor in determining the relative nuclear charge radius from the isotope shift. The new mass values of 10,11Be also allow for a more precise determination of the single-neutron binding energy of the halo neutron in 11Be.

  16. Extensive MIS 3 glaciation in southernmost Patagonia revealed by cosmogenic nuclide dating of outwash sediments

    NASA Astrophysics Data System (ADS)

    Darvill, Christopher M.; Bentley, Michael J.; Stokes, Chris R.; Hein, Andrew S.; Rodés, Ángel

    2015-11-01

    The timing and extent of former glacial advances can demonstrate leads and lags during periods of climatic change and their forcing, but this requires robust glacial chronologies. In parts of southernmost Patagonia, dating pre-global Last Glacial Maximum (gLGM) ice limits has proven difficult due to post-deposition processes affecting the build-up of cosmogenic nuclides in moraine boulders. Here we provide ages for the Río Cullen and San Sebastián glacial limits of the former Bahía Inútil-San Sebastián (BI-SSb) ice lobe on Tierra del Fuego (53-54°S), previously hypothesised to represent advances during Marine Isotope Stages (MIS) 12 and 10, respectively. Our approach uses cosmogenic 10Be and 26Al exposure dating, but targets glacial outwash associated with these limits and uses depth-profiles and surface cobble samples, thereby accounting for surface deflation and inheritance. The data reveal that the limits formed more recently than previously thought, giving ages of 45.6 ka (+139.9/-14.3) for the Río Cullen, and 30.1 ka (+45.6/-23.1) for the San Sebastián limits. These dates indicate extensive glaciation in southern Patagonia during MIS 3, prior to the well-constrained, but much less extensive MIS 2 (gLGM) limit. This suggests the pattern of ice advances in the region was different to northern Patagonia, with the terrestrial limits relating to the last glacial cycle, rather than progressively less extensive glaciations over hundreds of thousands of years. However, the dates are consistent with MIS 3 glaciation elsewhere in the southern mid-latitudes, and the combination of cooler summers and warmer winters with increased precipitation, may have caused extensive glaciation prior to the gLGM.

  17. Cosmogenic Nuclide Surficial Age Comparison between Boulders and Desert Pavement in the Mojave Desert, California

    NASA Astrophysics Data System (ADS)

    Blumentritt, D.; Perg, L. A.; Oskin, M. E.

    2005-12-01

    Cosmogenic nuclides can be an effective way to analyze surface ages when proper sampling strategies are employed given the depositional environment, erosion history, and approximate age of the surface. Recent cosmogenic dating work was performed on the Sheep Springs Wash alluvial terraces in the Rodman Mountains, Mojave Desert, California. Clast types on the terraces are predominantly quartz monzonite and basalt. Sampling strategies primarily included the tops of boulders (40-120 cm in diameter), which are thought to be the best representation of surface exposure ages. Complimentary surface samples were also collected from the incipient desert pavement for comparison to boulder ages. Desert pavement clasts were slightly angular, some with flat faces, and some with stream-rounded edges. 10Be concentration ages measured from quartz monzonite boulders and amalgamated desert pavement clasts have similar values where the average ages are 58.7 ka and 55.4 ka, respectively, and the maximum ages are nearly identical (63.4 and 63.2 ka), with the greatest discrepancy in the minimum ages of 56.0 ka (boulder) and 48.5 ka (pavement). These ages indicate two possible pavement clast sources, (1) they are from the original stream channel deposit, or (2) they are the result of boulder spalling. Given that many of the pavement surfaces are located in low boulder density areas, contain a wide variety of clast types, including spallation-resistant basalt, and pavement ages are not consistently higher than boulder ages, our contention is that the desert pavement is primarily derived from small clasts deposited on the surface just prior to its abandonment. Contamination of desert pavement samples from clasts exhumed from deeper in the terrace does not appear to have significantly altered its age. Desert pavements may be more attractive to sample because they are far less strenuous and time consuming to collect.

  18. Removal of Radioactive Nuclides from Mo-99 Acidic Liquid Waste - 13027

    SciTech Connect

    Hsiao, Hsien-Ming; Pen, Ben-Li

    2013-07-01

    About 200 liters highly radioactive acidic liquid waste originating from Mo-99 production was stored at INER (Institute of Nuclear Energy Research). A study regarding the treatment of the radioactive acidic liquid waste was conducted to solve storage-related issues and allow discharge of the waste while avoiding environmental pollution. Before discharging the liquid waste, the acidity, NO{sub 3}{sup -} and Hg ions in high concentrations, and radionuclides must comply with environmental regulations. Therefore, the treatment plan was to neutralize the acidic liquid waste, remove key radionuclides to reduce the dose rate, and then remove the nitrate and mercury ions. Bench tests revealed that NaOH is the preferred solution to neutralize the high acidic waste solution and the pH of solution must be adjusted to 9∼11 prior to the removal of nuclides. Significant precipitation was produced when the pH of solution reached 9. NaNO{sub 3} was the major content in the precipitate and part of NaNO{sub 3} was too fine to be completely collected by filter paper with a pore size of approximately 3 μm. The residual fine particles remaining in solution therefore blocked the adsorption column during operation. Two kinds of adsorbents were employed for Cs-137 and a third for Sr-90 removal to minimize cost. For personnel radiation protection, significant lead shielding was required at a number of points in the process. The final process design and treatment facilities successfully treated the waste solutions and allowed for environmentally compliant discharge. (authors)

  19. On a solar origin for the cosmogenic nuclide event of 775 A.D

    SciTech Connect

    Cliver, E. W.; Tylka, A. J.; Dietrich, W. F.; Ling, A. G.

    2014-01-20

    We explore requirements for a solar particle event (SPE) and flare capable of producing the cosmogenic nuclide event of 775 A.D., and review solar circumstances at that time. A solar source for 775 would require a >1 GV spectrum ∼45 times stronger than that of the intense high-energy SPE of 1956 February 23. This implies a >30 MeV proton fluence (F {sub 30}) of ∼8 × 10{sup 10} proton cm{sup –2}, ∼10 times larger than that of the strongest 3 month interval of SPE activity in the modern era. This inferred F {sub 30} value for the 775 SPE is inconsistent with the occurrence probability distribution for >30 MeV solar proton events. The best guess value for the soft X-ray classification (total energy) of an associated flare is ∼X230 (∼9 × 10{sup 33} erg). For comparison, the flares on 2003 November 4 and 1859 September 1 had observed/inferred values of ∼X35 (∼10{sup 33} erg) and ∼X45 (∼2 × 10{sup 33} erg), respectively. The estimated size of the source active region for a ∼10{sup 34} erg flare is ∼2.5 times that of the largest region yet recorded. The 775 event occurred during a period of relatively low solar activity, with a peak smoothed amplitude about half that of the second half of the 20th century. The ∼1945-1995 interval, the most active of the last ∼2000 yr, failed to witness a SPE comparable to that required for the proposed solar event in 775. These considerations challenge a recent suggestion that the 775 event is likely of solar origin.

  20. Cosmogenic nuclide evidence for low weathering and denudation in the wet, tropical highlands of Sri Lanka

    NASA Astrophysics Data System (ADS)

    von Blanckenburg, Friedhelm; Hewawasam, Tilak; Kubik, Peter W.

    2004-09-01

    Some of the lowest weathering and erosion rates in any mountain range in the world have been measured using cosmogenic nuclides in the steep, humid, tropical highlands of Sri Lanka. The total preanthropogenic denudation rates were measured in creek sediments and soil samples from unperturbed rain forest sites, bedrock from mountain crests, and bedrock from inselbergs. Denudation rates are in the range of 5-30 t km-2 yr-1 (2-11 mm ky-1). These rates average denudation over the last 50-250 ky. Weathering exports in rivers draining the mountainous Central Highlands show that silicate weathering rates are also low, varying from 5 to 20 t km-2 yr-1 today (2-7 mm ky-1), but they represent a significant fraction of the total denudation. All these observations run contrary to the conventional geomorphologic and geochemical wisdom that would predict rapid erosion for highlands of high relief, temperatures, and precipitation. We speculate that the high relief in Sri Lanka represents the remnant of a geomorphic block that was uplifted during rifting at 130 Ma or even earlier and that was reduced to the interior of the island by rapid receding of escarpments after continental breakup. It is possible that throughout this history, hillslopes, where not exposing bare bedrock, were protected by thick weathered profiles. Such clay-rich layers would inhibit silicate weathering by shielding bedrock from weathering agents. In the absence of landscape rejuvenation, physical erosion rates are low, and fresh mineral surfaces are not being supplied. The observation that wet, steep, tropical highlands can have low rates of rock weathering and erosion has some potentially profound implications for the long-term controls of atmospheric CO2 budgets: High temperature and precipitation, which are much invoked though controversial agents for silicate dissolution and CO2 drawdown, become ineffective in promoting weathering in areas that are not tectonically active.

  1. On a Solar Origin for the Cosmogenic Nuclide Event of 775 A.D.

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Tylka, A. J.; Dietrich, W. F.; Ling, A. G.

    2014-01-01

    We explore requirements for a solar particle event (SPE) and flare capable of producing the cosmogenic nuclide event of 775 A.D., and review solar circumstances at that time. A solar source for 775 would require a greater than 1 GV spectrum approximately 45 times stronger than that of the intense high-energy SPE of 1956 February 23. This implies a greater than 30 MeV proton fluence (F(sub 30)) of approximately 8 × 10(exp 10) proton cm(exp -2), approximately 10 times larger than that of the strongest 3 month interval of SPE activity in the modern era. This inferred F(sub 30) value for the 775 SPE is inconsistent with the occurrence probability distribution for greater than 30 MeV solar proton events. The best guess value for the soft X-ray classification (total energy) of an associated flare is approximately X230 (approximately 9 × 10(exp 33) erg). For comparison, the flares on 2003 November 4 and 1859 September 1 had observed/inferred values of approximately X35 (approximately 10(exp 33) erg) and approximately X45 (approximately 2 × 10(exp 33) erg), respectively. The estimated size of the source active region for a approximately 10(exp 34) erg flare is approximately 2.5 times that of the largest region yet recorded. The 775 event occurred during a period of relatively low solar activity, with a peak smoothed amplitude about half that of the second half of the 20th century. The approximately 1945-1995 interval, the most active of the last approximately 2000 yr, failed to witness a SPE comparable to that required for the proposed solar event in 775. These considerations challenge a recent suggestion that the 775 event is likely of solar origin.

  2. Deglacial history of the Pensacola Mountains, Antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating

    NASA Astrophysics Data System (ADS)

    Bentley, M. J.; Hein, A. S.; Sugden, D. E.; Whitehouse, P. L.; Shanks, R.; Xu, S.; Freeman, S. P. H. T.

    2017-02-01

    The retreat history of the Antarctic Ice Sheet is important for understanding rapid deglaciation, as well as to constrain numerical ice sheet models and ice loading models required for glacial isostatic adjustment modelling. There is particular debate about the extent of grounded ice in the Weddell Sea embayment at the Last Glacial Maximum, and its subsequent deglacial history. Here we provide a new dataset of geomorphological observations and cosmogenic nuclide surface exposure ages of erratic samples that constrain the deglacial history of the Pensacola Mountains, adjacent to the present day Foundation Ice Stream and Academy Glacier in the southern Weddell Sea embayment. We show there is evidence of at least two glaciations, the first of which was relatively old and warm-based, and a more recent cold-based glaciation. During the most recent glaciation ice thickened by at least 450 m in the Williams Hills and at least 380 m on Mt Bragg. Progressive thinning from these sites was well underway by 10 ka BP and ice reached present levels by 2.5 ka BP, and is broadly similar to the relatively modest thinning histories in the southern Ellsworth Mountains. The thinning history is consistent with, but does not mandate, a Late Holocene retreat of the grounding line to a smaller-than-present configuration, as has been recently hypothesized based on ice sheet and glacial isostatic modelling. The data also show that clasts with complex exposure histories are pervasive and that clast recycling is highly site-dependent. These new data provide constraints on a reconstruction of the retreat history of the formerly-expanded Foundation Ice Stream, derived using a numerical flowband model.

  3. Dissecting Reactor Antineutrino Flux Calculations.

    PubMed

    Sonzogni, A A; McCutchan, E A; Hayes, A C

    2017-09-15

    Current predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from ^{235}U, ^{239}Pu, ^{241}Pu and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In the present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the Huber-Mueller antineutrino spectra, including the ^{238}U contribution as well as the effective charge and the allowed shape assumption used in the conversion method. We observe that including a shape correction of about +6%  MeV^{-1} in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.

  4. Dissecting Reactor Antineutrino Flux Calculations

    NASA Astrophysics Data System (ADS)

    Sonzogni, A. A.; McCutchan, E. A.; Hayes, A. C.

    2017-09-01

    Current predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from 235U, 239Pu, 241Pu and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In the present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the Huber-Mueller antineutrino spectra, including the 238U contribution as well as the effective charge and the allowed shape assumption used in the conversion method. We observe that including a shape correction of about +6 % MeV-1 in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.

  5. Dissecting Reactor Antineutrino Flux Calculations

    DOE PAGES

    Sonzogni, A. A.; McCutchan, E. A.; Hayes, A. C.

    2017-09-15

    Current predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from 235 U , 239 Pu , 241 Pu and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In our present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the Huber-Mueller antineutrino spectra, including the 238 U contribution as wellmore » as the effective charge and the allowed shape assumption used in the conversion method. Here, we observe that including a shape correction of about + 6 % MeV - 1 in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.« less

  6. Results of calculations of external gamma radiation exposure rates from local fallout and the related radionuclide compositions of two hypothetical 1-MT nuclear bursts. Final report

    SciTech Connect

    Hicks, H.

    1984-12-01

    This report presents data on calculated gamma radiation exposure rates and local surface deposition of related radionuclides resulting from two hypothetical 1-Mt nuclear bursts. Calculations are made of the debris from two types of bombs: one containing /sup 235/U as a fissionable material (designated oralloy), the other containing /sup 238/U (designated tuballoy). 4 references.

  7. The Gas-Filled-Magnet at PRIME Lab: Increased Sensitivity of Cosmogenic Nuclide Measurements

    NASA Astrophysics Data System (ADS)

    Caffee, M. W.; Granger, D. E.; Woodruff, T. E.

    2015-12-01

    Abstract: Using accelerator mass spectrometry (AMS), radionuclides produced either by cosmic-ray interactions or by nucleogenic means can be measured. Typical isotopic abundance ratios range from 1 x 10-10 to 1 x 10-15. The routinely measured radionuclides are 10Be, 14C, 26Al, 36Cl, and 129I. Be-10, 26Al, and 36Cl have isobaric interferences that cannot be eliminated mass through mass analysis, but dE/dx techniques suppresses these isobars enough to allow successful measurements. There are compromises, the isobar for 26Al, 26Mg, precludes successful measurement of 26Al if AlO- is injected into the accelerator. Mg- doesn't form a stable negative ion so a 26Al measurement requires injection of 26Al-. But the Al- ion is formed inefficiently; secondary ion currents using Al- are ~ 10 times less than an AlO- secondary ion beam. Precision scales with count rate so precise measurement of the 26Al/Al for all but higher ratio samples is difficult. It has long been recognized that a gas-filled-magnet (GFM) could potentially improve the measurement of those radionuclides with intractable isobar interferences. A GFM works on the principle that each element of an isobar pair, e.g. 26Mg and 26Al, has a different average charge state as it traverses a gas (3-4 Torr of N2) contained within the vacuum jacket of a magnet. The magnet steers each species with its own momentum-to-charge ratio on its own distinct radius of curvature. The magnet can be tuned to allow the isotope of interest into a dE/dx detector; most of the isobar doesn't make it into the detector. Using the PRIME Lab GFM we are now able to routinely run 26Al with a precision that is comparable to that obtained with 10Be. We are also using the GFM for routine measurements of 10Be and 36Cl. Although the improvement for these nuclides is not as pronounced as it is for 26Al, the GFM has improved the detection sensitivity for both. Our 10Be background is now ~ 5 x 10-16 and for 36Cl we can now run the source more

  8. Boulder, Pavement, Pit; Sample Selection for Cosmogenic Nuclide Dating on Alluvial Fans

    NASA Astrophysics Data System (ADS)

    Perg, L. A.; Oskin, M. E.; Blumentritt, D.; Strane, M.; Mukhopadhyay, S.

    2005-12-01

    Selecting sample targets and methods that minimize the effects of erosion, inheritance, and material movement is one of the largest issues facing cosmogenic isotope dating. Since sample material availability often sharply limits methods, establishing error estimates in less-than-ideal sampling situations is also important. Our study of alluvial fan offsets in the Eastern California Shear Zone (Mojave Desert) takes advantage of multiple sample targets to develop method inter-comparisons. Alluvial fans along the Calico fault had abundant large basalt and quartz monzonite boulders, targets for 3He and 10Be respectively. In addition to the boulders, the incipient desert pavement on the youngest alluvial fan surface was sampled. The basalt boulders had higher relative cosmogenic nuclide concentrations, and a much higher scatter, due to very high inheritance and also likely boulder recycling into younger terraces. The quartz monzonite had lower, consistent concentrations on the youngest terrace, but presented erosional concerns due to the spalling and grussification common to granitic material. The incipient desert pavement had a comparable 10Be concentration to the quartz monzonite boulders; the highest concentration in each was the same, and the average pavement concentration lagged the boulders only slightly. The Lenwood fault alluvial fans had two targets. Small clasts formed weakly developed to mature pavement on the surfaces. The fan deposits were also thick enough to dig pits (1.5m). On the younger fan surface, both sediment and clasts (gravel to cobble) were collected in the pit; concentrations were comparable between the two. The profiles indicated high inheritance (comparable to modern wash samples), and some mixing at the near surface. Due to high inheritance, the surface sample alone would far overestimate the age. Using wash samples to estimate inheritance slightly overcorrects, due to mixing in the near-surface. Two types of clasts were sampled in the older

  9. Beryllium-10 terrestrial cosmogenic nuclide surface exposure dating of Quaternary landforms in Death Valley

    NASA Astrophysics Data System (ADS)

    Owen, Lewis A.; Frankel, Kurt L.; Knott, Jeffrey R.; Reynhout, Scott; Finkel, Robert C.; Dolan, James F.; Lee, Jeffrey

    2011-02-01

    Quaternary alluvial fans, and shorelines, spits and beach bars were dated using 10Be terrestrial cosmogenic nuclide (TCN) surface exposure methods in Death Valley. The 10Be TCN ages show considerable variance on individual surfaces. Samples collected in the active channels date from ~ 6 ka to ~ 93 ka, showing that there is significant 10Be TCN inheritance within cobbles and boulders. This suggests that the predominantly bedrock hillslopes erode very slowly and sediment is transferred very gradually in most regions within Death Valley. Comparisons of 10Be TCN ages on alluvial fan surfaces with chronostratigraphies based on soil development and optically stimulated luminescence dating show that minimum 10Be TCN ages within sample sets on individual surfaces most closely approximate to the age of landforms that are younger than ~ 70 ka. Alluvial fan surfaces older than ~ 70 ka have begun to undergo sufficient erosion such that the majority of 10Be TCN ages for datasets on individual surfaces probably underestimate the true age of the surface due to erosion and exhumation of fresh cobbles and boulders. The spread of 10Be TCN ages for beach bars near Beatty Junction and shorelines ~ 8 km south of Furnace Creek is large, ranging from ~ 119 ka to ~ 385 ka and ~ 109 ka to ~ 465 ka, respectively. New and previously published luminescence ages and soil development suggest that these landforms may have formed during marine isotope stage (MIS) 2 (~ 22-18 ka), but these younger ages may reflect elluviation of material into the bar deposit long after deposition, and hence the younger ages do not record the true antiquity of the landforms. This disparity between dates determined by different dating methods and the large spread of TCN ages suggests that the cobbles and boulders have considerable inherited 10Be concentrations, suggesting that the clasts have been derived from older shorelines or associated landforms. These results highlight the problems associated with using

  10. Cosmogenic Nuclide Exposure Dating of the Tiltill Rock Avalanche, Yosemite National Park

    NASA Astrophysics Data System (ADS)

    Ford, K. R.; Pluhar, C. J.; Stone, J. O.; Stock, G. M.; Zimmerman, S. R.

    2013-12-01

    Yosemite National Park serves as an excellent natural laboratory for studying rock falls and rock avalanches because these are the main processes modifying the nearly vertical slopes of this recently glaciated landscape. Mass wasting represents a significant hazard in the region and the database of previous rock falls and other mass wasting events in Yosemite is extensive, dating back to the mid-1800s. However, this record is too short to capture the recurrence characteristics and triggering mechanisms of the very largest events, necessitating studies of the geologic record of mass wasting. Rock falls and rock avalanches are readily dated by cosmogenic nuclide methods due to their instantaneous formation, and results can be tied to triggering events such as seismic activity (e.g. Stock et al., 2009). Here, we apply exposure dating to the Holocene Tiltill rock avalanche north of Hetch Hetchy Reservoir. The deposit comprises what appear to be two separate lobes of rock and debris, yielding a total volume of ~3.1 x 106 m3. Assuming an erosion rate of 0.0006 cm/yr and neglecting snowpack shielding, preliminary data suggest a mean exposure age of 11,000 + 600 year B.P. for both deposits, indicating that they were emplaced in a single event. The age of the Tiltill 'slide' is similar to earthquakes on the Owens Valley Fault between 10,800 + 600 and 10,200 + 200 cal year B.P. (Bacon, 2007) and the White Mountain Fault, ~10,000 cal year B.P. (Reheis, 1996; DePolo, 1989). Given that movement on the Owens Valley fault in 1872 caused a number of rock falls in Yosemite and the coincidence of ages between the Tiltill 'slide' and paleoseismic events, a large earthquake in Eastern Sierra Nevada may have triggered this event. Other trigger events are also possibilities, but only through compilation of a database of large rock avalanches can statistically significant groupings of events begin to demonstrate whether seismic triggering is a dominant process.

  11. Silicon multistrip detectors and caesium iodide scintillator for identification of heavy and ultra heavy nuclides in space experiments

    NASA Astrophysics Data System (ADS)

    Miozza, Maurizio

    1997-03-01

    An instrument made of silicon multistrip detectors, time-of-flight and caesium iodide scintillators for ion identification in cosmic ray experiments has been constructed and tested. The charge dynamic of the preamplifier reading the silicon multistrip detectors allows to identify all the nuclides of the periodic table. A redundant method for measuring the ion energy, autotrigger capability and low power consumption of the silicon detector readout are the major characteristic features of the apparatus. Performance results of the instrument, tested with a calcium beam of 0.5 GeV/u at the GSI accelerator, are presented.

  12. [Bibliographic consideration of proper management of radioactive waste on short-lived period nuclides that are used in nuclear medicine].

    PubMed

    Kida, Tetsuo; Watanabe, Hiroshi; Yamaguchi, Ichirou; Nagaoka, Hiroaki; Fujibuchi, Toshioh; Tanaka, Shinji; Hayakawa, Toshio

    2009-05-20

    A rational clearance system for medical radioactive waste has not yet been established in Japan. As Europe and USA's ways, the establishment of DIS that medical radioactive waste what are kept in storage room for more than decided period each nuclide except from regulation of radiation's control. The purpose of this report is to clarify the problems with the establishment of DIS in Japan through a literature review of the experience in Europe and the USA and previous research that has been reported in Japan. To establish the DIS system, the radiation control system in nuclear medicine should be rebuilt and put into effect.

  13. Activity-composition relations in the system CaCO 3-MgCO 3 predicted from static structure energy calculations and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Vinograd, Victor L.; Burton, Benjamin P.; Gale, Julian D.; Allan, Neil L.; Winkler, Björn

    2007-02-01

    Thermodynamic mixing properties and subsolidus phase relations of the rhombohedral carbonate system, (1 - x) · CaCO 3 - x · MgCO 3, were modelled in the temperature range of 623-2023 K with static structure energy calculations based on well-parameterised empirical interatomic potentials. Relaxed static structure energies of a large set of randomly varied structures in a 4 × 4 × 1 supercell of R3¯c calcite ( a = 19.952 Å, c = 17.061 Å) were calculated with the General Utility Lattice Program (GULP). These energies were cluster expanded in a basis set of 12 pair-wise effective interactions. Temperature-dependent enthalpies of mixing were calculated by the Monte Carlo method. Free energies of mixing were obtained by thermodynamic integration of the Monte Carlo results. The calculated phase diagram is in good agreement with experimental phase boundaries.

  14. Analysis of burnup and isotopic compositions of BWR 9 x 9 UO{sub 2} fuel assemblies

    SciTech Connect

    Suzuki, M.; Yamamoto, T.; Ando, Y.; Nakajima, T.

    2012-07-01

    In order to extend isotopic composition data focusing on fission product nuclides, measurements are progressing using facilities of JAEA for five samples taken from high burnup BWR 9 x 9 UO{sub 2} fuel assemblies. Neutronics analysis with an infinite assembly model was applied to the preliminary measurement data using a continuous-energy Monte Carlo burnup calculation code MVP-BURN with nuclear libraries based on JENDL-3.3 and JENDL-4.0. The burnups of the samples were determined to be 28.0, 39.3, 56.6, 68.1, and 64.0 GWd/t by the Nd-148 method. They were compared with those calculated using node-average irradiation histories of power and in-channel void fractions which were taken from the plant data. The comparison results showed that the deviations of the calculated burnups from the measurements were -4 to 3%. It was confirmed that adopting the nuclear data library based on JENDL-4.0 reduced the deviations of the calculated isotopic compositions from the measurements for {sup 238}Pu, {sup 144}Nd, {sup 145}Nd, {sup 146}Nd, {sup 148}Nd, {sup 134}Cs, {sup 154}Eu, {sup 152}Sm, {sup 154}Gd, and {sup 157}Gd. On the other hand, the effect of the revision in the nuclear. data library on the neutronics analysis was not significant for major U and Pu isotopes. (authors)

  15. Calculator Cookery.

    ERIC Educational Resources Information Center

    Humphreys, Casey; And Others

    This valuable collection of materials was developed to incorporate the calculator as an instructional aid in ninth- and tenth-grade general and basic mathematics classes. The materials are also appropriate for grades 7 and 8. After an introductory section which teaches the use of the calculator, four games and activities are described. For these…

  16. Nuclear medical imaging using β+γ coincidences from 44Sc radio-nuclide with liquid xenon as detection medium

    NASA Astrophysics Data System (ADS)

    Grignon, C.; Barbet, J.; Bardiès, M.; Carlier, T.; Chatal, J. F.; Couturier, O.; Cussonneau, J. P.; Faivre, A.; Ferrer, L.; Girault, S.; Haruyama, T.; Le Ray, P.; Luquin, L.; Lupone, S.; Métivier, V.; Morteau, E.; Servagent, N.; Thers, D.

    2007-02-01

    We report on a new nuclear medical imaging technique based on the measurement of the emitter location in the three dimensions with a few mm spatial resolution using β+γ emitters. Such measurement could be realized thanks to a new kind of radio-nuclides which emit a γ-ray quasi-simultaneously with the β+ decay. The most interesting radio-nuclide candidate, namely 44Sc, will be potentially produced at the Nantes cyclotron ARRONAX. The principle is to reconstruct the intersection of the classical line of response (obtained with a standard PET camera) with the direction cone defined by the third γ-ray. The emission angle measurement of this additional γ-ray involves the use of a Compton telescope for which a new generation of camera based on a liquid xenon (LXe) time projection chamber is considered. GEANT3 simulations of a large acceptance LXe Compton telescope combined with a commercial micro-PET (LSO crystals) have been performed and the obtained results will be presented. They demonstrate that a good image can be obtained from the accumulation of each three-dimensional measured position. A spatial resolution of 2.3 mm has been reached with an injected activity of 0.5 MBq for a 44Sc point source emitter.

  17. Comparative study of beta-decay data for eight nuclides measured at the Physikalisch-Technische Bundesanstalt

    NASA Astrophysics Data System (ADS)

    Sturrock, P. A.; Fischbach, E.; Javorsek, D.; Jenkins, J. H.; Lee, R. H.; Nistor, J.; Scargle, J. D.

    2014-07-01

    We present the results of time-series analyses of data, kindly provided by the Physikalisch-Technische Bundesanstalt, concerning the beta-decays of Ag108, Ba133, Cs137, Eu152, Eu154, Kr85, Ra226, and Sr90. From measurements of the detector currents, we find evidence of annual oscillations (especially for Ra226), and for several solar r-mode oscillations. It is notable that the frequencies of these r-mode oscillations correspond to exactly the same sidereal rotation rate (12.08 year-1) that we have previously identified in r-mode oscillations detected in both Mt Wilson solar diameter data and Lomonosov Moscow State University Sr90 beta-decay data. Ba133 is found to be anomalous in that current measurements for this nuclide have a much larger variation (by 4 σ) than those of the other nuclides. It is interesting that analysis of variability measurements in the PTB files yields strong evidence for an oscillation for Ba133 but only weak evidence for Ra226.

  18. Alpha spectroscopy of nuclides produced in the interaction of 5 GeV protons with heavy element targets

    NASA Astrophysics Data System (ADS)

    Bowman, J. David; Eppley, Richard E.; Hyde, Earl K.

    1982-02-01

    Alpha particle energies were redetermined to an accuracy of 2 to 5 keV for a group of 40 neutron-deficient nuclides with atomic numbers ranging from 65 to 88. Improved half-life values were measured for 10 of these nuclides. Weightless samples containing mixtures of these activities were prepared by use of the helium jet transport technique to remove spallation and fragmentation products recoiling from targets of U, Th, Au, and Ta bombarded with 5 GeV protons. Experimental and calibration techniques are discussed in detail. Implications of the results for the mechanism of reaction of 5 GeV protons with complex targets are briefly discussed. RADIOACTIVITY 5 GeV p + U, Th, Au, Ta; separated recoil products by helium jet; measured Eα, t12 151Dy, 154Er, 150Dy, 152Ho, 152Hom, 151Ho, 151Hom, 153Er, 152Er, 154Tm, 154Tmm, 153Tm, 179Pt, 155Yb, 178Pt, 177Pt, 176Pt, 199Pom, 198Po, 212Fr, 197Pom, 213Fr, 212Ra; measured Eα 149Tb, 211At, 204Fr, 222Ac, 217At, 218Rn, 219Fr, 211Po, 214Po, 217Rn, 216At, 218Fr, 215At, 213Po, 212Po, 214At, 211Pom; reaction mechanisms discussed.

  19. Spatial and temporal variations in denudation rates derived from cosmogenic nuclides in four European fluvial terrace sequences

    NASA Astrophysics Data System (ADS)

    Schaller, M.; Ehlers, T. A.; Stor, T.; Torrent, J.; Lobato, L.; Christl, M.; Vockenhuber, C.

    2016-12-01

    The denudation of landscapes is affected by temporal and spatial variations in tectonics, climate, and vegetation. However, deciphering the contributions of these different processes has proven challenging. In this study, cosmogenic nuclide-derived modern and paleo catchment-wide denudation rates in four European rivers are investigated. We present 12 new and 4 recalculated cosmogenic nuclide-derived denudation rates from modern river sediments and 14 paleo-denudation rates from terraces deposited over the last 2 Ma. The catchments studied are located in regions with minimal Quaternary tectonic activity and span different climates over 12o latitude. Results indicate that modern denudation rates range between 16 ± 11 and 51 ± 7 mm/ka with no clear latitudinal variation. Modern denudation rates are compared with catchment geomorphic indices including slope, fluvial steepness index, and relief. The denudation rates correlate better to catchment topographic indices (R2 ≈ 0.4) rather than climate. Paleo-denudation rates range from 8 ± 7 to 56 ± 7 mm/ka and are associated with a possible increase in the average paleo-denudation rates over the past 2 Ma. Taken together, the results indicate that quantification of catchment-wide denudation rates over long (Quaternary) time scales because of climate change is difficult. Future work to study climate influence on denudation rates should focus on the successes of previous work that document transient denudation rates over shorter and more recent time scales, i.e., from the Last Glacial Maximum to present.

  20. Monte Carlo calculation of artificial radionuclide radiation dose rates for marine species in the Western Pacific.

    PubMed

    Su, Jian; Yu, Wen; Zeng, Zhi; Ma, Hao; Chen, Liqi; Cheng, Jianping

    2014-03-01

    After the Fukushima nuclear accident, there is a widespread concern over the radioactive contamination of the marine environment. To protect non-human species, a radiation dose rate calculation model for Western Pacific marine species was established. Ten kinds of marine species in the Western Pacific were modelled by Geant4 for Monte Carlo simulation. Organisms were modelled with two ellipsoids: one represented organs and the other represented muscle. The enhanced dose rates by 10 main kinds of nuclides were calculated. According to the reported activities of three main nuclides ((134)Cs, (137)Cs and (131)I) in seawater near Fukushima coastal, the radiation risks of marine species were estimated. The results showed that the marine species near the Fukushima accident drain outlets might be at risk. But organisms that were >15 km away from the drain outlets were relatively safe.

  1. Application of Origen2.1 in the decay photon spectrum calculation of spallation products

    NASA Astrophysics Data System (ADS)

    Hong, Shuang; Yang, Yong-Wei; Xu, Hu-Shan; Meng, Hai-Yan; Zhang, Lu; Liu, Zhao-Qing; Gao, Yu-Cui; Chen, Kang

    2016-11-01

    Origen2.1 is a widely used computer code for calculating the burnup, decay, and processing of radioactive materials. However, the nuclide library of Origen2.1 is used for existing reactors like pressurized water reactors. To calculate the photon spectrum released by the decay of spallation products, we have made specific libraries for the ADS tungsten spallation target, based on the results given by the FLUKA Monte Carlo code. All the data used to make the Origen2.1 libraries are obtained from Nuclear structure & decay Data (NuDat2.6). The accumulated activity of spallation products and the contribution of nuclides to photon emission are given in this paper. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03030102)

  2. Monte Carlo simulation of GCR neutron capture production of cosmogenic nuclides in stony meteorites and lunar surface

    NASA Astrophysics Data System (ADS)

    KolláR, D.; Michel, R.; Masarik, J.

    2006-03-01

    A purely physical model based on a Monte Carlo simulation of galactic cosmic ray (GCR) particle interaction with meteoroids is used to investigate neutron interactions down to thermal energies. Experimental and/or evaluated excitation functions are used to calculate neutron capture production rates as a function of the size of the meteoroid and the depth below its surface. Presented are the depth profiles of cosmogenic radionuclides 36Cl, 41Ca, 60Co, 59Ni, and 129I for meteoroid radii from 10 cm up to 500 cm and a 2π irradiation. Effects of bulk chemical composition on n-capture processes are studied and discussed for various chondritic and lunar compositions. The mean GCR particle flux over the last 300 ka was determined from the comparison of simulations with measured 41Ca activities in the Apollo 15 drill core. The determined value significantly differs from that obtained using equivalent models of spallation residue production.

  3. Natural Paleoseismometers: Cosmogenic Nuclide Dating of Precariously Balanced Rocks (PBRs) - Integral Constraints on Maximum Ground Accelerations

    NASA Astrophysics Data System (ADS)

    Perg, L. A.; Ludwig, L. G.; Kendrick, K.; Brune, J.; Purvance, M.; Anooshehpoor, R.; Akciz, S.

    2007-12-01

    Precariously balanced rocks (PBRs) act as natural seismometers constraining maximum ground acceleration over the surface exposure history of the PBR. These key paleoseismic indicators have the potential to validate ground motions on the timescale necessary to test earthquake rupture forecasts and Seismic Hazard Assessment estimates, and are an active topic of research to validate CyberShake results and constrain National Seismic Hazard Maps. This research focuses on examining the post-exhumation history of PBRs using in-situ terrestrial cosmogenic nuclides (TCNs). TCNs provide a record of near-surface exposure history. The measured concentrations are a function of the residence time in the upper ~20 m of the subsurface (inherited concentration), the timing and rate of exhumation, and post-exhumation surface spalling and chemical erosion. Our goal in the project is to provide reasonable constraints on the post-exhumation history, specifically the age of the PBRs and evolution of precariousness: we should be able to constrain whether the rocks were of similar precariousness 2.5 ka, 5 ka, and 10 ka ago. These specific targets will provide important constraints on time since exceedance for the CyberShake models. We developed our sampling strategy to address subsurface inheritance, exhumation rate and timing, and post- exhumation spalling and chemical erosion. PBRs were selected to meet a variety of considerations. These rocks constrain ground motions from large earthquakes on the San Jacinto and Elsinore faults, in Southern California. Inherited concentrations lead to an age estimate that is too old; we are investigating inherited concentrations though sampling a rock quarry near Perris CA, with shielded samples at greater than 15 m depth. We also have partially shielded samples from the interior of rocks toppled to measure their stability, and through vandalism. To determine exhumation age and rate, our sampling strategy is to collect 5-6 samples per PBR: 1 on top, 3

  4. Using cosmogenic nuclides to date the stabilisation age of relict rockglaciers

    NASA Astrophysics Data System (ADS)

    Kronig, Olivia; Reitner, Jürgen M.; Christl, Marcus; Ivy-Ochs, Susan

    2017-04-01

    Active rockglaciers are periglacial landforms which are creeping down mountain slopes due to plastic deformation of the interstitial ice. The occurrence of active rockglaciers is an indicator of Alpine permafrost. Relict rockglaciers are not moving anymore because the ice melted, but they give evidence for the earlier existence of permafrost. In the Alps, relict rockglaciers can often be found below today's tree line raising the question of when these landforms have last been active. Judging from the present position of the relict rockglaciers, the lower permafrost limit during the time of their activity must have been hundreds of meters lower than it is today. Already in the early days of rockglacier research, the potential of relict rockglaciers as a paleoclimate proxy was recognised (Barsch 1977, Haeberli 1985). However, obtaining absolute ages on relict rockglaciers has always been a major difficulty. Lately it has been shown that with cosmogenic nuclides it is possible to date the stabilisation age of relict rockglaciers, but it has been applied only in a few cases (Ivy-Ochs et al. 2009). According to Reitner (2007), the lowest relict rockglaciers of the eastern Alps, the Tandl rockglaciers, are located in the Province of Carinthia (Austria). The Tandl rockglaciers are a complex series of rockglaciers spanning from around 2300 m down to 1220 m a.s.l. Due to their low position and based on modelling estimates on permafrost distribution in the area (Avian & Kellerer-Pirklbauer 2012), it is plausible that these low rockglaciers were active even prior to the Younger Dryas. Therefore, samples from the entire rockglacier series were taken for 10Be exposure dating. Furthermore, the close proximity of the rockglaciers to moraines associated to the Gschnitz stadial allow comparing the dating results to equilibrium line depression reconstructions. Less than 10 km to the southwest, a second rockglacier series, the Norbert rockglaciers, was sampled. In contrast to the

  5. Terrestrial Cosmogenic-Nuclide Dating of Alluvial Fans in Death Valley, California

    USGS Publications Warehouse

    Machette, Michael N.; Slate, Janet L.; Phillips, Fred M.

    2008-01-01

    We have used terrestrial cosmogenic nuclides (TCN) to establish the age of some of the most extensive Quaternary alluvial fans in Death Valley, California. These intermediate-age alluvial fans are most extensive on the western side of the valley, where tectonic deformation is considerably less pronounced than on the eastern side of the valley. These fans are characterized by a relatively smooth, densely packed desert pavement formed by well-varnished (blackened) clasts. These surfaces have been mapped as the Q2 gravel by previous workers and as unit Qai (intermediate age) by us. However, the intermediate-age gravels probably contain multiple subunits, as evidenced by slight differences in morphologic expression, soil formation, and inset geomorphic relations. The TCN technique used herein sums the cosmogenic 36Cl in approximately 2.5-meter-deep profiles through soil and host alluvium, thus avoiding some of the problems associated with the more typical surface-exposure dating of boulders or smaller clasts. Our TCN 36Cl dating of 12 depth profiles indicates that these intermediate-age (Qai) alluvial fans range from about 100 to 40 kilo-annum (ka), with a mean age of about 70 ka. An alternative interpretation is that alluvial unit Qai was deposited in two discrete episodes from 90 to 80 ka and from 60 to 50 ka, before and after MIS (marine oxygen-isotope stage) 4 (respectively). Without an intermediate-age unit, such as MIS 4 lake deposits, we can neither disprove nor prove that Qai was deposited in two discrete intervals or over a longer range of time. Thus, in Death Valley, alluvial unit Qai largely brackets MIS 4, which is not associated with a deep phase of Lake Manly. These Qai fans extend to elevations of about -46 meters (150 feet below sea level) and have not been transgressed by Lake Manly, suggesting that MIS 4 or MIS 2 lakes were rather shallow in Death Valley, perhaps because they lacked inflow from surface runoff of the Sierra Nevada drainages through

  6. Potential resolution of discrepancies between scaling models for in situ cosmogenic nuclide production rates

    NASA Astrophysics Data System (ADS)

    Lifton, N. A.

    2010-12-01

    Two main types of theoretical models are used currently for scaling in situ cosmogenic nuclide (CN) production rates in time and space, distinguished primarily by the data on which they are based. The first of these, that of Lal (1991, EPSL 104, p. 424, reparameterized by Stone, 2000, JGR 105, p. 23,753), is based on atmospheric measurements of nuclear disintegrations in photographic emulsions combined with data from various neutron detectors sensitive to different portions of the secondary cosmic-ray spectrum. The other published models for scaling CN production rates (Dunai, 2001, EPSL 193, p 197; Lifton et al. 2005, EPSL 239, p. 140; Desilets and Zreda, 2006, EPSL 206, p 21) are based (either largely or entirely) on data from neutron monitors, which all sample similar portions of the cosmic-ray spectrum. A further distinction is that the neutron monitor-based models accommodate a time-dependent geomagnetic field, while the Lal model does not. While both model types yield similar predictions for sites in middle to high latitudes and low to middle altitudes (<2 km), predictions diverge at low latitudes and high altitudes. This discrepancy arises primarily from the different altitude dependences of each data source - neutron monitor-based models predict a faster increase in cosmic ray intensity with altitude than does the Lal model. Unfortunately, previously published production rate calibration data (e.g., Balco et al., 2008, Quat. Geochron. 3, p. 174) were neither sufficiently consistent among sites nor adequately precise to identify which of these models was correct. The CRONUS-Earth Project, which aims to better characterize production rate systematics for all commonly measured CNs, has been working to resolve this discrepancy. A potential solution may be found in the atmospheric cosmic ray flux models of Sato and Niita (2006, Radiation Res. 166, p. 544) and Sato et al. (2008, Radiation Res. 170, p. 244), combined with new, high-precision in situ cosmogenic 10

  7. MEMS Calculator

    National Institute of Standards and Technology Data Gateway

    SRD 166 MEMS Calculator (Web, free access)   This MEMS Calculator determines the following thin film properties from data taken with an optical interferometer or comparable instrument: a) residual strain from fixed-fixed beams, b) strain gradient from cantilevers, c) step heights or thicknesses from step-height test structures, and d) in-plane lengths or deflections. Then, residual stress and stress gradient calculations can be made after an optical vibrometer or comparable instrument is used to obtain Young's modulus from resonating cantilevers or fixed-fixed beams. In addition, wafer bond strength is determined from micro-chevron test structures using a material test machine.

  8. Evaluation of the chemical composition and correlation between the calculated and measured odour concentration of odorous gases from a landfill in Beijing, China

    NASA Astrophysics Data System (ADS)

    Wu, Chuandong; Liu, Jiemin; Zhao, Peng; Li, Wenhui; Yan, Luchun; Piringer, Martin; Schauberger, Günther

    2017-09-01

    Odorous gases emitted from landfills have always been a public concern, but studies evaluating the odour contribution and the correlation between the odour concentrations are limited. The objectives of this study were to assess the odour contribution and to correlate the measured odour concentration COD with the calculated odour concentration SOAV, which was calculated as sum of individual odour activity value (OAV). Odorous air samples from a landfill in Beijing were collected seasonally and measured by both gas chromatography and an olfactometer. Different from previous studies, we measured the odour threshold of 51 detected compounds using a uniform methodology to minimize the imprecision of citing odour threshold from disparate literature. The odour threshold is used to convert the individual chemical concentration into the OAV, which is used as a surrogate of the odour concentration. Evaluation of the OAV revealed that hydrogen sulfide (65.9%), dimethyl sulfide (14.4%) and trimethylamine (8.6%) contributed the most to the odour at the landfill. Moreover, the correlation between the calculated odour concentration SOAV and the measured odour concentration COD resulted in a linear regression equation of COD = 6.28 SOAV (r = 0.914, n = 24, p < 0.01). Based on the scaling factor K = 6.28, the average ratio of calculated odour concentration to measured odour concentration could be improved from less than 0.2 to 1.1. By the calibration of the calculated odour concentration SOAV, it is possible to use continuous measurements of chemical concentrations to derive odour concentration for this site for monitoring purposes.

  9. Chemical composition analysis of the essential oil of Melissa officinalis L. from Kurdistan, Iran by HS/SPME method and calculation of the biophysicochemical coefficients of the components.

    PubMed

    Taherpour, Avat Arman; Maroofi, Hossein; Rafie, Zeinab; Larijani, Kambiz

    2012-01-01

    The volatile constituents of the essential oil of wild Melissa officinalis L. obtained from the Kurdistan province of Iran were extracted by headspace/solid-phase micro-extraction and were analysed by gas chromatography and gas chromatography/mass spectrometry. Of a total of 14 compounds in the oil, 12 (85.7%) were identified. The main components were as follows: (E)-citral (37.2%), neral (23.9%) and citronellal (20.3%). Some physicochemical properties, such as the logarithm of calculated octanol-water partitioning coefficients (log K (ow))(,) total biodegradation (TB (d) in mol h(-1) and g h(-1)), water solubility (S (w), mg L(-1) at 25°C) and median lethal concentration 50 (LC(50)), were calculated for compounds 1-14 from M. officinalis L.

  10. A counter-intuitive approach to calculating non-exchangeable 2H isotopic composition of hair: treating the molar exchange fraction fE as a process-related rather than compound-specific variable

    USGS Publications Warehouse

    Landwehr, J.M.; Meier-Augenstein, W.; Kemp, H.F.

    2011-01-01

    Hair is a keratinous tissue that incorporates hydrogen from material that an animal consumes but it is metabolically inert following synthesis. The stable hydrogen isotope composition of hair has been used in ecological studies to track migrations of mammals as well as for forensic and archaeological purposes to determine the provenance of human remains or the recent geographic life trajectory of living people. Measurement of the total hydrogen isotopic composition of a hair sample yields a composite value comprised of both metabolically informative, non-exchangeable hydrogen and exchangeable hydrogen, with the latter reflecting ambient or sample preparation conditions. Neither of these attributes is directly measurable, and the non-exchangeable hydrogen composition is obtained by estimation using a commonly applied mathematical expression incorporating sample measurements obtained from two distinct equilibration procedures. This commonly used approach treats the fraction of exchangeable hydrogen as a mixing ratio, with a minimal procedural fractionation factor assumed to be close or equal to 1. Instead, we propose to use full molar ratios to derive an expression for the non-exchangeable hydrogen composition explicitly as a function of both the procedural fractionation factor α and the molar hydrogen exchange fraction fE. We apply these derivations in a longitudinal study of a hair sample and demonstrate that the molar hydrogen exchange fraction fE should, like the procedural fractionation factor α, be treated as a process-dependent parameter, i.e. a reaction-specific constant. This is a counter-intuitive notion given that maximum theoretical values for the molar hydrogen exchange fraction fE can be calculated that are arguably protein-type specific and, as such, fE could be regarded as a compound-specific constant. We also make some additional suggestions for future approaches to determine the non-exchangeable hydrogen composition of hair and the use of

  11. Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

    NASA Technical Reports Server (NTRS)

    Mckeown, A B; Belles, Frank E

    1954-01-01

    Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein.

  12. Cosmogenic nuclide concentrations in Neogene rivers of the Great Plains reveal the evolution of fluvial storage and recycling

    NASA Astrophysics Data System (ADS)

    Sinclair, Hugh; Stuart, Fin; McCann, Louise; Tao, Zui

    2016-04-01

    The measurement of the duration of near surface residence of sediment grains from the stratigraphic record has the potential to quantitatively reconstruct processes such as stratal condensation, sediment recycling and the exposure histories of unconformities. Geomorphological measurements of dates and rates of surfaces and erosion respectively has enabled significant advances in understanding, however, the radiogenic half life of typical cosmogenic nuclides such as 10Be and 26Al means they are not suitable for the stratigraphic record. Instead, we have applied the stable cosmogenic nuclide of 21Ne to quartz-rich sediment to quantify the routing history of the river systems that have drained the southern Rockies of Wyoming and Colorado during Neogene times. The Neogene sediments of Nebraska record fluvial systems of the Great Plains that flow from the Rockies towards the east and into the Mississippi catchment. This succession is <300 m thick, and records successive episodes of fluvial incision and aggradation associated with regional tilting from 6 to 4 Ma and periods of climate change. As part of an evaluation of the application of 21Ne to the stratigraphic record, we sampled quartzite pebbles from an Upper Miocene, Pliocene and modern river channel of the North Platte approximately 400 km from their mountainous source. The quartzite is derived from a single exposure of the Medicine Bow quartzites in Wyoming, therefore all three intervals recorded the same travel distance from source. Additionally, we know the erosion rate of the Medicine Bow quartzites from detrital 10Be analyses, and we also sampled shielded bedrock samples from the quartzite to evaluate for any non-cosmogenic 21Ne. This means that the concentrations of 21Ne in detrital pebbles >400 km from their source could be corrected for both inherited non-cosmogenic and erosion induced accumulation at source. Therefore, any additional amounts of 21Ne must record storage and exposure during transport down

  13. Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH2C≡N), a Compound of Potential Astrochemical Interest.

    PubMed

    Samdal, Svein; Møllendal, Harald; Carles, Sophie

    2015-08-27

    The rotational spectrum of cyanomethyl formate (HC(O)OCH2C≡N) has been recorded in the 12–123 GHz spectral range. The spectra of two conformers were assigned. The rotamer denoted I has a symmetry plane and two out-of plane hydrogen atoms belonging to the cyanomethyl (CH2CN) moiety. In the conformer called II, the cyanomethyl group is rotated 80.3° out of this plane. Conformer I has an energy that is 1.4(6) kJ/mol lower than the energy of II according to relative intensity measurements. A large number of rotational transitions have been assigned for the ground and vibrationally excited states of the two conformers and accurate spectroscopic constants have been obtained. These constants should predict frequencies of transitions outside the investigated spectral range with a very high degree of precision. It is suggested that cyanomethyl formate is a potential interstellar compound. This suggestion is based on the fact that its congener methyl formate (HC(O)OCH3) exists across a large variety of interstellar environments and the fact that cyanides are very prevalent in the Universe. The experimental work has been augmented by high-level quantum chemical calculations. The CCSD/cc-pVQZ calculations are found to predict structures of the two forms that are very close to the Born–Oppenheimer equilibrium structures. MP2/cc-pVTZ predictions of several vibration–rotation interaction constants were generally found to be rather inaccurate. A gas-phase reaction between methyl formate and the cyanomethyl radical CH2CN to produce a hydrogen atom and cyanomethyl formate was mimicked using MP2/cc-pVTZ calculations. It was found that this reaction is not favored thermodynamically. It is also conjectured that the possible formation of cyanomethyl formate might be catalyzed and take place on interstellar particles.

  14. Total Energy Calculations using DFT+DMFT: Application to the Pressure-composition Phase Diagram of Rare-earth Element Nickelates

    NASA Astrophysics Data System (ADS)

    Park, Hyowon

    2014-03-01

    Ab-initio total energy calculations have been implemented within the fully self-consistent density functional theory plus dynamical mean field theory (DFT+DMFT) method, using a Wannier orbital basis. The method is used to calculate the structural and metal-insulator transition phase diagrams of the rare-earth element nickelate RNiO3 perovskites as a function of rare-earth ion, pressure and temperature. This phase diagram is of interest because the insulating phase arises from a remarkable site-selective Mott state, in which unusual electronic physics is strongly coupled to a breathing-mode Ni-O bond disproportionation. Conventional DFT fails to stabilize the breathing distortion and thus does not reproduce the insulating phase. DFT+U overpredicts order, in particular finding that La NiO3 is disproportionated, in disagreement with experiment. In contrast to these theories, the DFT+DMFT method can quantitatively reproduce the metal-insulator and structural phase diagram of all RNiO3 perovskites in the plane of pressure and rare-earth elements. The calculated temperature dependence of the energetics of the phase transformation indicates that the thermal transition is driven by phonon entropy effects. This present method can be generally applied to nano-structured or artificially structured strongly correlated materials including heterostructures and thin films, whose electronic phases are strongly coupled to their lattice degrees of freedom. The authors acknowledge funding from the U. S. Army Research Office via grant No. W911NF0910345 56032PH, US Department of Energy under grant DOE-ER-046169, and in part by FAME, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

  15. Fluorine in titanite: an overlooked matrix compositional parameter that can affect accuracy of calculated U/Pb ages measured by SIMS

    NASA Astrophysics Data System (ADS)

    Coble, M. A.

    2016-12-01

    Geo/thermochronology based upon U/Pb and/or Pb/Pb analysis of titanite (CaTiSiO5) has proven useful for understanding the P-T-t evolution of many igneous, metamorphic, and authigenic rock samples. Titanites can be challenging to analyze, however, because they are characteristically low-U and exhibit a wide range of compositional variation (notably OH, F, Na, Al, Fe, Y, Zr, Nb, REE, Hf, Th, U). This can cause isobaric interferences that make it challenging to find matrix-matched standards, particularly for secondary ion mass spectrometry (SIMS) analyses. Titanite U/Pb and Pb/Pb ages and trace element analyses were acquired by SIMS using SHRIMP-RG from 11 natural titanite reference materials with independently measured radiometric ages and 5 undated samples from the Stanford mineral collection. These measurements were used to evaluate the accuracy of U/Pb ages and the ionization and extraction efficiencies for Th+, U+, ThO+, UO+, ThF+, UF+ species (corresponding to m/e = 232, 238, 248, 254, 251, 257) for samples from a wide range of compositions and petrologic settings. Molecular ion ratios such as UO+/U+, UO2+/U+ or UO2+/UO+ are generally measured to correct 238U/206Pb for instrument mass fractionation. This approach becomes problematic for F-rich minerals, such as titanite, because 238U16O+ and 235U19F+ completely overlap at m/e = 254. REE-oxide and -fluoride molecules are also abundant in the mass spectra. New analyses reveal that UF+ production relative to U+ from titanites on SHRIMP-RG ranges from 0.05 to 2.0 and scales with F content (900 to 32,000 ppm). These results show that overlooking fluorine as a matrix compositional parameter can produce inaccurately young or reversely discordant U/Pb ages in samples where the F content differs significantly from the standard. In extreme cases, titanite U/Pb ages can be up to 10% younger than accepted values. Strategies to minimize or correct for F-related artifacts with instrument tuning and use of matrix

  16. Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS

    SciTech Connect

    Perkasa, Y. S.; Waris, A. Kurniadi, R. Su'ud, Z.

    2014-09-30

    Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS have been conducted. In this work, fission cross section resulted from MCNP6 prediction will be compared with result from TALYS calculation. MCNP6 with its event generator CEM03.03 and LAQGSM03.03 have been validated and verified for several intermediate and heavy nuclides fission reaction data and also has a good agreement with experimental data for fission reaction that induced by photons, pions, and nucleons at energy from several ten of MeV to about 1 TeV. The calculation that induced within TALYS will be focused mainly to several hundred MeV for actinide and sub-actinide nuclides and will be compared with MCNP6 code and several experimental data from other evaluator.

  17. Explicitly correlated benchmark calculations on C8H8 isomer energy separations: how accurate are DFT, double-hybrid, and composite ab initio procedures?

    NASA Astrophysics Data System (ADS)

    Karton, Amir; Martin, Jan M. L.

    2012-10-01

    Accurate isomerization energies are obtained for a set of 45 C8H8 isomers by means of the high-level, ab initio W1-F12 thermochemical protocol. The 45 isomers involve a range of hydrocarbon functional groups, including (linear and cyclic) polyacetylene, polyyne, and cumulene moieties, as well as aromatic, anti-aromatic, and highly-strained rings. Performance of a variety of DFT functionals for the isomerization energies is evaluated. This proves to be a challenging test: only six of the 56 tested functionals attain root mean square deviations (RMSDs) below 3 kcal mol-1 (the performance of MP2), namely: 2.9 (B972-D), 2.8 (PW6B95), 2.7 (B3PW91-D), 2.2 (PWPB95-D3), 2.1 (ωB97X-D), and 1.2 (DSD-PBEP86) kcal mol-1. Isomers involving highly-strained fused rings or long cumulenic chains provide a 'torture test' for most functionals. Finally, we evaluate the performance of composite procedures (e.g. G4, G4(MP2), CBS-QB3, and CBS-APNO), as well as that of standard ab initio procedures (e.g. MP2, SCS-MP2, MP4, CCSD, and SCS-CCSD). Both connected triples and post-MP4 singles and doubles are important for accurate results. SCS-MP2 actually outperforms MP4(SDQ) for this problem, while SCS-MP3 yields similar performance as CCSD and slightly bests MP4. All the tested empirical composite procedures show excellent performance with RMSDs below 1 kcal mol-1.

  18. Comparison of seasonal variations in water-use efficiency calculated from the carbon isotope composition of tree rings and flux data in a temperate forest.

    PubMed

    Michelot, Alice; Eglin, Thomas; Dufrêne, Eric; Lelarge-Trouverie, Caroline; Damesin, Claire

    2011-02-01

    Tree-ring δ(13) C is often interpreted in terms of intrinsic water-use efficiency (WUE) using a carbon isotope discrimination model established at the leaf level. We examined whether intra-ring δ(13) C could be used to assess variations in intrinsic WUE (W(g), the ratio of carbon assimilation and stomatal conductance to water) and variations in ecosystem WUE (W(t) , the ratio of C assimilation and transpiration) at a seasonal scale. Intra-ring δ(13) C was measured in 30- to 60-µm-thick slices in eight oak trees (Quercus petraea). Canopy W(g) was simulated using a physiologically process-based model. High between-tree variability was observed in the seasonal variations of intra-ring δ(13) C. Six trees showed significant positive correlations between W(g) calculated from intra-ring δ(13) C and canopy W(g) averaged over several days during latewood formation. These results suggest that latewood is a seasonal recorder of W(g) trends, with a temporal lag corresponding to the mixing time of sugars in the phloem. These six trees also showed significant negative correlations between photosynthetic discrimination Δ calculated from intra-ring δ(13) C, and ecosystem W(t), during latewood formation. Despite the observed between-tree variability, these results indicate that intra-ring δ(13) C can be used to access seasonal variations in past W(t).

  19. Influence of breast composition and interseed attenuation in dose calculations for post-implant assessment of permanent breast 103Pd seed implant

    NASA Astrophysics Data System (ADS)

    Afsharpour, Hossein; Pignol, Jean-Philippe; Keller, Brian; Carrier, Jean-François; Reniers, Brigitte; Verhaegen, Frank; Beaulieu, Luc

    2010-08-01

    The impact of tissue heterogeneity and interseed attenuation is studied in post-implant evaluation of five clinical permanent breast 103Pd seed implants using the Monte Carlo (MC) dose calculation method. Dose metrics for the target (PTV) as well as an organ at risk (skin) are used to visualize the differences between a TG43-like MC method and more accurate MC methods capable of considering the breast tissue heterogeneity as well as the interseed attenuation. PTV dose is reduced when using a breast tissue model instead of water in MC calculations while the dose to the skin is increased. Furthermore, we investigate the effect of varying the glandular/adipose proportion of the breast tissue on dose distributions. The dose to the PTV (skin) decreases (increases) with the increasing adipose proportion inside the breast. In a complete geometry and compared to a TG43-like situation, the average PTV D90 reduction varies from 3.9% in a glandular breast to 35.5% when the breast consists entirely of adipose. The skin D10 increases by 28.2% in an entirely adipose breast. The results of this work show the importance of an accurate and patient-dependent breast tissue model to be used in the dosimetry for this kind of low energy implant.

  20. Chlorine-36 in fossil rat urine: An archive of cosmogenic nuclide deposition during the past 40,000 years

    SciTech Connect

    Plummer, M.A.; Phillips, F.M.; Fabryka-Martin, J.

    1997-07-25

    Knowledge of the production history of cosmogenic nuclides, which is needed for geological and archaeological dating, has been uncertain. Measurements of chlorine-36/chlorine ({sup 36}Cl/Cl) ratios in fossil packrat middens from Nevada that are radiocarbon-dated between about 38 thousand years ago (ka) and the present showed that {sup 36}Cl/Cl ratios were higher by a factor of about 2 before {approx} 11 ka. This raises the possibility that cosmogenic production rates just before the close of the Pleistocene were up to 50% higher than is suggested by carbon-14 calibration data. The discrepancy could be explained by addition of low-carbon-14 carbon dioxide to the atmosphere during that period, which would have depressed atmospheric radiocarbon activity. Alternatively, climatic effects on {sup 36}Cl deposition may have enhanced the {sup 36}Cl/Cl ratios. 49 refs., 3 figs.

  1. Influence of heavy natural radioactive nuclides introduced in soil with labelled fertilizers and ameliorants on cytogenetic effects in plants

    SciTech Connect

    Arkhipov, N.P.; Bazylev, V.V.; Bobrikova, E.T.; Fevraleva, L.T.; Kal'chenko, VA.; Shevchenko, V.A.

    1985-05-01

    The effect of heavy natural radioactive nuclides (STYU, STSTh, SSWRa, S Po, and S Pb) in labeled fertilizers and ameliorants on the number of meiotic chromosome aberrations was studied in field experiments on the major crop plants, wheat, barley and corn. The mining and use of coal and oil and the processing of raw materials in the production of rare and nonferrous metals produce high quantities of wastes with an elevated content of natural radionuclides. One possible way for technogenically altering the natural radiation background of soil is the active utilization of phosphorus fertilizers in agriculture, and also the use, as fertilizers and ameliorants of wastes from nonferrous metallurgy, of the ash from heat and power plants and various intermediates from the chemical industry. The authors conclude that the introduction of labeled ammophos, nitrophos and phosphogypsum, which raised the soil background concentration of the specified elements, produced an increase in the number of cells with meiotic chromosome aberrations.

  2. Precision Mass Measurements of Short-Lived Nuclides at The Heavy-Ion Storage Ring in Lanzhou

    NASA Astrophysics Data System (ADS)

    Zhang, Yuhu; Xu, Hushan; Litvinov, Yuri A.

    Recent commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou enabled us to conduct high-precision mass measurements at the Institute of Modern Physics in Lanzhou (IMP). In the past few years, mass measurements were performed using the CSRe-based isochronous mass spectrometry employing the fragmentation of the energetic beams of 58Ni, 78Kr, 86Kr, and 112Sn projectiles. Masses of short-lived nuclides of on both sides of the stability valley were addressed. Relative mass precision of down to 10-6-10-7 is routinely achieved. The mass values were used as an input for dedicated nuclear structure and astrophysics studies, providing for instance new insights into the rp-process of nucleosynthesis in X-ray bursts. In this contribution, we briefly review the so far conducted experiments and the main achieved results, as well as outline the plans for future experiments.

  3. Toward using millennial-scale geomagnetic field models to constrain in situ cosmogenic nuclide production rate variations

    NASA Astrophysics Data System (ADS)

    Lifton, N. A.

    2005-12-01

    The geomagnetic field exerts a strong influence on the trajectories of charged primary cosmic-ray particles incident on the Earth's atmosphere (and therefore, on the geographic distribution of their progeny). The resulting cascade of secondary particles then interacts with the top few meters of the Earth's surface to produce various nuclides in situ (in situ cosmogenic nuclides, or CNs). With appropriate interpretive models, concentrations of these nuclides measured in terrestrial materials can be used to infer the duration of surface exposure (or of burial following exposure) and rates of various surficial processes. However, the potential precision with which CNs can be applied is limited by how well their production rates are known. Nuclide production rates are typically determined by measuring CN concentrations in surficial rocks with well-constrained exposure histories. Scaling these time-integrated production rates to other locations with different exposure durations, though, requires knowledge or assumptions of how instantaneous production rates have varied in space and time. Spatial scaling of CN production rates is typically described by models based on modern secondary cosmic-ray measurements, ordered by parameters linked to the geomagnetic field. In general, the most robust parameter for ordering these measurements is the effective vertical cutoff rigidity (RC), a measure of the energy required for primary cosmic rays to penetrate the geomagnetic and magnetospheric fields and interact with the atmosphere at a given location. Temporal variations in CN production rates at a given site result primarily from changes in the orientation and intensity of the geomagnetic field. These geomagnetic variations have been modeled for CN applications using estimates of Holocene variations in dipole orientation combined with records of global dipole intensity variations. It has typically been assumed in CN research that secular variation of the geomagnetic pole averages

  4. Firewood calculator

    SciTech Connect

    Clark, A.; Curtis, A.B.; Darwin, W.N.

    1981-01-01

    Rotating cardboard discs are used to read off total tree or topwood firewood volume (tons or cords) that can be expected from trees of d.b.h. 6 to 24 inches and tree height 10 to 90 feet. One side of the calculator is used for broadleaved species with deliquescent crowns and the other side for braodleaves with excurrent crowns.

  5. Fate of nuclides in natural-water systems. Annual progress report, October 1, 1981-March 31, 1983

    SciTech Connect

    Turekian, K.K.

    1982-11-30

    The atmospheric fluxes of /sup 210/Pb and /sup 7/Be at New Haven, CT, and Bermuda were determined and compared with model fluxes. The reliability of these radionuclides as tracers for other chemical species injected into the atmosphere by human activity was therefore tested. The distribution of /sup 10/Be in soil profiles was studied. The initial aim was to use the standing crop of /sup 10/Be in the soil to obtain an exposure age of the surface. Dated surfaces (i.e. raised coastal terraces, dated volcanic flows, etc) showed that /sup 10/Be does not totally accumulate in the soils but is mobilized. The mean residence time appears to be about 20,000 years. In a related study a number of the members of the /sup 238/U and /sup 232/Th decay series nuclides were measured in the major ground water aquifer types in Connecticut. Using /sup 222/Rn as a flux indicator it was possible to determine the adsorption and desorption coefficients, distribution coefficients and retardation factors of Ra, Pb, and Th in these aquifers. The study of the transport of nuclides by the Connecticut River and the study of the Amazon River plume were completed. Also completed was one of the most intensive studies of the behavior of natural radionuclides and plutonium in an estuarine system, the Long Island Sound, by analyzing two nearshore sites (SACHEM and FOAM) to complement the deep water sites (NWC and DEEP). The chronologies of accumulation, bioturbation, human disturbance and physical change were established for these varied environments.

  6. Gaussian Modification of Neutrino Energy Losses in Electron Capture Processes of Nuclides 56Fe, 56Co, 56Ni and 56Mn in Stellar Interiors

    NASA Astrophysics Data System (ADS)

    Liu, Jing-jing; Luo, Zhi-quan

    2010-10-01

    By using the Gaussian modification method, the neutrino energy losses in the electron capture processes of nuclides 56Fe, 56Co, 56Ni and 56Mn are investigated. The results show that the energy loss rate of neutrinos is increased due to the Gaussian modification of the energy level distribution of the Gamow-Teller (GT) resonance transitions of nuclides. In the reactions dominated by the electron capture processes of the low-energy transitions, the Gaussian modification has a very small influence on the neutrino energy losses. When the high-energy G-T resonance transition is the main electron capture process, the influence on the neutrino energy losses will be greatly increased. For example, the correctional differences of nuclide 56Fe are about 2 orders of magnitude when the density ρ7 = 100 (ρ7 is in units of 10 7 mol × cm -3) and the half width of Gaussian function Δ = 14.3, 18.3, 22.3 Mev, and those of nuclide 56Ni are about 60% and 40% when Δ = 6.3, 18.3 Mev, respectively.

  7. Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident.

    PubMed

    Saito, Kimiaki; Tanihata, Isao; Fujiwara, Mamoru; Saito, Takashi; Shimoura, Susumu; Otsuka, Takaharu; Onda, Yuichi; Hoshi, Masaharu; Ikeuchi, Yoshihiro; Takahashi, Fumiaki; Kinouchi, Nobuyuki; Saegusa, Jun; Seki, Akiyuki; Takemiya, Hiroshi; Shibata, Tokushi

    2015-01-01

    Soil deposition density maps of gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident were constructed on the basis of results from large-scale soil sampling. In total 10,915 soil samples were collected at 2168 locations. Gamma rays emitted from the samples were measured by Ge detectors and analyzed using a reliable unified method. The determined radioactivity was corrected to that of June 14, 2011 by considering the intrinsic decay constant of each nuclide. Finally the deposition maps were created for (134)Cs, (137)Cs, (131)I, (129m)Te and (110m)Ag. The radioactivity ratio of (134)Cs-(137)Cs was almost constant at 0.91 regardless of the locations of soil sampling. The radioactivity ratios of (131)I and (129m)Te-(137)Cs were relatively high in the regions south of the Fukushima NPP site. Effective doses for 50 y after the accident were evaluated for external and inhalation exposures due to the observed radioactive nuclides. The radiation doses from radioactive cesium were found to be much higher than those from the other radioactive nuclides. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. HPLC analysis of complete BZ systems. Evolution of the chemical composition in cerium and ferroin catalysed batch oscillators: experiments and model calculations.

    PubMed

    Hegedús, L; Wittmann, M; Noszticzius, Z; Yan, S; Sirimungkala, A; Försterling, H D; Field, R J

    2001-01-01

    In the last few years many new reaction routes and intermediates have been discovered in the mechanism of the Belousov-Zhabotinsky (BZ) reaction with the aid of high performance liquid chromatography (HPLC). These previous HPLC studies, however, were limited to the Ce(4+)-organic substrate (malonic or bromomalonic acid) systems only. Very recently some measurements were made on a cerium catalysed full BZ system but only in its induction period. The present work follows the evolution of the main chemical components in a cerium and in a ferroin catalysed full BZ system from the start until the end of the oscillatory regime in a batch reactor. While recording the potential oscillations of a bromide selective electrode we measured from time to time the concentration of the following components: malonic and bromomalonic acids and bromate as main components; malonyl malonate, ethanetetracarboxylic and bromoethenetricarboxylic acids which are recombination products of organic free radicals; oxidized intermediates: tartronic, oxalic (OA) and mesoxalic (MOA) acids, and brominated products: dibromoacetic and tribromoacetic acids. Recombination products are generated in the intervals when the autocatalytic reaction is "switched off". In the course of the autocatalytic periods, however, the organic radicals react with the inorganic bromine dioxide radical mainly which leads to the formation of MOA and OA. Due to a very fast Ce(4+)-MOA reaction, MOA can be detected in the ferroin catalysed BZ system only. Our model calculations deal exclusively with the cerium catalysed system. The suggested new Marburg-Budapest-Missoula (MBM) model includes both negative feedback loops (bromous acid-bromide ion Oregonator type and bromine dioxide-organic free radicals Radicalator type feedback) and the recently discovered radical-radical recombination reactions. Comparison of the experimental data with the model calculations shows a good qualitative agreement but some open problems still

  9. Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties

    USGS Publications Warehouse

    Solum, J.G.; Davatzes, N.C.; Lockner, D.A.

    2010-01-01

    The presence of clays in fault rocks influences both the mechanical and hydrologic properties of clay-bearing faults, and therefore it is critical to understand the origin of clays in fault rocks and their distributions is of great importance for defining fundamental properties of faults in the shallow crust. Field mapping shows that layers of clay gouge and shale smear are common along the Moab Fault, from exposures with throws ranging from 10 to ???1000 m. Elemental analyses of four locations along the Moab Fault show that fault rocks are enriched in clays at R191 and Bartlett Wash, but that this clay enrichment occurred at different times and was associated with different fluids. Fault rocks at Corral and Courthouse Canyons show little difference in elemental composition from adjacent protolith, suggesting that formation of fault rocks at those locations is governed by mechanical processes. Friction tests show that these authigenic clays result in fault zone weakening, and potentially influence the style of failure along the fault (seismogenic vs. aseismic) and potentially influence the amount of fluid loss associated with coseismic dilation. Scanning electron microscopy shows that authigenesis promotes that continuity of slip surfaces, thereby enhancing seal capacity. The occurrence of the authigenesis, and its influence on the sealing properties of faults, highlights the importance of determining the processes that control this phenomenon. ?? 2010 Elsevier Ltd.

  10. Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications II. Users Manual and Program Description. 2; Users Manual and Program Description

    NASA Technical Reports Server (NTRS)

    McBride, Bonnie J.; Gordon, Sanford

    1996-01-01

    This users manual is the second part of a two-part report describing the NASA Lewis CEA (Chemical Equilibrium with Applications) program. The program obtains chemical equilibrium compositions of complex mixtures with applications to several types of problems. The topics presented in this manual are: (1) details for preparing input data sets; (2) a description of output tables for various types of problems; (3) the overall modular organization of the program with information on how to make modifications; (4) a description of the function of each subroutine; (5) error messages and their significance; and (6) a number of examples that illustrate various types of problems handled by CEA and that cover many of the options available in both input and output. Seven appendixes give information on the thermodynamic and thermal transport data used in CEA; some information on common variables used in or generated by the equilibrium module; and output tables for 14 example problems. The CEA program was written in ANSI standard FORTRAN 77. CEA should work on any system with sufficient storage. There are about 6300 lines in the source code, which uses about 225 kilobytes of memory. The compiled program takes about 975 kilobytes.

  11. Calculation Software

    NASA Technical Reports Server (NTRS)

    1994-01-01

    MathSoft Plus 5.0 is a calculation software package for electrical engineers and computer scientists who need advanced math functionality. It incorporates SmartMath, an expert system that determines a strategy for solving difficult mathematical problems. SmartMath was the result of the integration into Mathcad of CLIPS, a NASA-developed shell for creating expert systems. By using CLIPS, MathSoft, Inc. was able to save the time and money involved in writing the original program.

  12. A Multi-nuclide Approach to the Exposure Timing of Alpine Summits in Northwestern Svalbard: Results from in-situ 14C Measurements in Quartz

    NASA Astrophysics Data System (ADS)

    Lamp, J. L.; Schaefer, J. M.; Koffman, T. N. B.; Briner, J. P.; Gjermundsen, E. F.; Young, N. E.; Hormes, A.

    2016-12-01

    Deglaciation histories of the Polar Regions provide important insights into ice-sheet and climate dynamics, but cosmogenic nuclide surface exposure studies from these cold and arid regions based on stable (3He and 21Ne) or long-lived (10Be and 26Al) isotopes are frequently hampered by the problem of cosmogenic nuclide inheritance from prior exposure periods. In-situ 14C can add complementary information in such cases, as its half-life is only 5730 years. 14C is essentially reset during periods of significant glaciation lasting longer than 20,000 years, and therefore does not suffer from the same inheritance complication of longer lived nuclides. Additionally, 14C is produced and retained in the ubiquitous mineral quartz, making it applicable in most terrestrial settings, and, when coupled with 10Be and 26Al measurements, can provide a better understanding of landscape evolution during the Holocene and late Pleistocene. Here we present a multi-nuclide approach to the timing and duration of exposure of steep alpine summits in Northwestern Spitsbergen, including a new 14C dataset from quartz. It remains unclear whether Svalbard was overwhelmed by the marine-based Barents-Kara Ice Sheet during the Last Glacial Maximum, or if there were ice-free nunataks. Our 14C results show that peaks in the Northwest region of Svalbard have remained ice-free or under only a thin ice cover, since at least the late Pleistocene. The data strengthen the conclusions of 10Be/26Al nuclide studies which imply that these peaks exhibit extremely low erosion rates in comparison to other steep, glaciated, alpine landscapes during the Quaternary, and support the use of 14C as a method to better elucidate the recent glacial history and surface processes in polar locales.

  13. Miocene to recent ice elevation variations from the interior of the West Antarctic ice sheet: Constraints from geologic observations, cosmogenic nuclides and ice sheet modeling

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sujoy; Ackert, Robert P.; Pope, Allen E.; Pollard, David; DeConto, Robert M.

    2012-07-01

    Observations of long-term West Antarctic Ice Sheet (WAIS) behavior can be used to test and constrain dynamic ice sheet models. Long-term observational constraints are however, rare. Here we present the first constraints on long-term (Miocene-Holocene) WAIS elevation from the interior of the ice sheet near the WAIS divide. We use geologic observations and measurements of cosmogenic 21Ne and 10Be in bedrock surfaces to constrain WAIS elevation variations to <160 m above the present-day ice levels since 7 Ma, and <110 m above present-day ice levels since 5.4 Ma. The cosmogenic nuclide data indicate that bedrock surfaces 35 m above the present-day ice levels had near continuous exposure over the past 3.5 Ma, requiring average interior WAIS elevations to have been similar to, or lower than present, since the beginning of the Pliocene warm period. We use a continental ice sheet model to simulate the history of ice cover at our sampling sites and thereby compute the expected concentration of the cosmogenic nuclides. The ice sheet model indicates that during the past 5 Ma interior WAIS elevations of >65 m above present-day ice levels at the Ohio Range occur only rarely during brief ice sheet highstands, consistent with the observed cosmogenic nuclide data. Furthermore, the model's prediction that highstand elevations have increased on average since the Pliocene is in good agreement with the cosmogenic nuclide data that indicate the highest ice elevation over the past 5 Ma was reached during the highstand at 11 ka. Since the simulated cosmogenic nuclide concentrations derived from the model's ice elevation history are in good agreement with our measurements, we suggest that the model's prediction of more frequent collapsed-WAIS states and smaller WAIS volumes during the Pliocene are also correct.

  14. The use of interval calculation technique for fuel characteristic uncertainty estimations into a fuel cycle

    SciTech Connect

    Kamayev, D. A.; Kolesov, V. V.; Ukraintsev, V. F.; Hitrik, D. V.

    2006-07-01

    Authors realized a technique of the Cauchy problem decision for system of the linear equations (isotope kinetics) with use of interval arithmetic for the fuel burning up problem. Thus there is an opportunity to research a neutron flux, fission and capture cross-section uncertainties impact (and also of nuclide yield and decay constants) on nuclide concentration uncertainties and, accordingly, on change of a fuel cycle characteristics (such K{sub eff}, breeding ratio etc). We also carried out research of sensitivity of concentration uncertainties to uncertainties of neutron flux and uncertainties of the initial cross-section data. Calculations were carried out for neutron flux uncertainties of 1 % and 5 % and for uncertainties in the initial cross-section data of 1 % for {sup 235}U and {sup 238}U. Results are presented for one and three years of a reactor operation. (authors)

  15. Major- and minor-metal composition of three distinct solid material fractions associated with Juan de Fuca hydrothermal fluids (northeast Pacific), and calculation of dilution fluid samples

    USGS Publications Warehouse

    Hinkley, T.K.; Seeley, J.L.; Tatsumoto, M.

    1988-01-01

    Three distinct types of solid material are associated with each sample of the hydrothermal fluid that was collected from the vents of the Southern Juan de Fuca Ridge. The solid materials appear to be representative of deposits on ocean floors near mid-ocean ridges, and interpretation of the chemistry of the hydrothermal solutions requires understanding of them. Sr isotopic evidence indicates that at least two and probably all three of these solid materials were removed from the solution with which they are associated, by precipitation or adsorption. This occurred after the "pure" hydrothermal fluid was diluted and thoroughly mixed with ambient seawater. The three types of solid materials, are, respectively, a coarse Zn- and Fe-rich material with small amounts of Na and Ca; a finer material also rich in Zn and Fe, but with alkali and alkaline-earth metals; and a scum composed of Ba or Zn, with either considerable Fe or Si, and Sr. Mineral identification is uncertain because of uncertain anion composition. Only in the cases of Ba and Zn were metal masses greater in solid materials than in the associated fluids. For all other metals measured, masses in fluids dwarf those in solids. The fluids themselves contain greater concentrations of all metals measured, except Mg, than seawater. We discuss in detail the relative merits of two methods of determining the mixing proportions of "pure" hydrothermal solution and seawater in the fluids, one based on Sr isotopes, and another previously used method based on Mg concentrations. Comparison of solute concentrations in the several samples shows that degree of dilution of "pure" hydrothermal solutions by seawater, and amounts of original solutes that were removed from it as solid materials, are not related. There is no clear evidence that appreciable amounts of solid materials were not conserved (lost) either during or prior to sample collection. ?? 1988.

  16. WBGT Calculator

    SciTech Connect

    Hunter, Charles H.

    2000-05-22

    This software calculates a Wet Bulb Globe Temperature (WBGT) using standard measurements from a meteorological station. WBGT is used by Industrial Hygenists (IH) to determine heat stress potential to outdoor workers. Through the mid 1990''s, SRS technicians were dispatched several times daily to measure WBGT with a custom hand held instrument and results were dessiminated via telephone. Due to workforce reductions, the WSRC IH Department asked for the development of an automated method to simulate the WBGT measurement using existing real time data from the Atmospheric Technologies Group''s meteorological monitoring network.

  17. Novel Solvent for the Simultaneous recovery of Radioactive Nuclides from Liquid Radioactive Wastes

    SciTech Connect

    Romanovskiy, Valeriy Nicholiavich; Smirnov, Lgor V.; Babain, Vasiliy A.; Todd, Terry A.; Brewer, Ken N.

    1999-10-07

    The present invention relates to solvents, and methods, for selectively extracting and recovering radionuclides, especially cesium and strontium, rare earths and actinides from liquid radioactive wastes. More specifically, the invention relates to extracting agent solvent compositions comprising complex organoboron compounds, substituted polyethylene glycols, and neutral organophosphorus compounds in a diluent. The preferred solvent comprises a chlorinated cobalt dicarbollide, diphenyl-dibutylmethylenecarbamoylphosphine oxide, PEG-400, and a diluent of phenylpolyfluoroalkyl sulfone. The invention also provides a method of using the invention extracting agents to recover cesium, strontium, rare earths and actinides from liquid radioactive waste.

  18. Nuclear chemistry of returned lunar samples: Nuclide analysis by gamma-ray spectrometry

    NASA Technical Reports Server (NTRS)

    Kelley, G. D.; Eldridge, J. S.

    1972-01-01

    Concentrations of primordial radioelements and of cosmogenic radionuclides in crystalline rocks, breccias, and soils from the Ocean of Storms were determined. Concentrations of K, Th, U, Al-26, and Na-22 were determined for seven clastic or brecciated rocks, three sieved samples of fines, and one composite sample of sawdust from the cutting of a fragmental rock, all from samples obtained on the Apollo 14 mission. The K, Th, and U concentrations and cogmogenic radionuclide abundances in rocks and soils from Apollo 15 are also discussed.

  19. Neutron activation analysis of nuclides from stellar and man-induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Oliver, L. L.

    Neutron activation and gamma counting were used to determine the relative abundances of six stable tellurium isotopes in the acid-etched residues of the Allende meteorite. The results were correlated with the isotopic compositions of xenon and the elemental abundances of helium and neon in similarly prepared residues. Nucleosynthesis appears to be the only viable explanation or the anomalous isotopic and elemental compositions observed in these residues. Results suggest that the solar system condensed from an isotopically and chemically zoned nebula that was produced by the explosion of a supernova, concentric with the present Sun. A combination of neutron activation and mass spectrometry was used to determine the concentrations of fissiogenic iodine 129 and stable iodine 127 in rain, milk and the thyroids of man, cow and deer from Missouri. Rain and deer thyroids show the highest average values of the iodine 129/iodine 127 ratio. Milk and the thyroids of cattle and humans show successively lower values of the iodine 129/iodine 127 ratio due to dietary additives of mineral iodine and to biological averaging.

  20. Hybrid reduced order modeling for assembly calculations

    SciTech Connect

    Bang, Youngsuk; Abdel-Khalik, Hany S.; Jessee, Matthew A.; Mertyurek, Ugur

    2015-08-14

    While the accuracy of assembly calculations has greatly improved due to the increase in computer power enabling more refined description of the phase space and use of more sophisticated numerical algorithms, the computational cost continues to increase which limits the full utilization of their effectiveness for routine engineering analysis. Reduced order modeling is a mathematical vehicle that scales down the dimensionality of large-scale numerical problems to enable their repeated executions on small computing environment, often available to end users. This is done by capturing the most dominant underlying relationships between the model's inputs and outputs. Previous works demonstrated the use of the reduced order modeling for a single physics code, such as a radiation transport calculation. This paper extends those works to coupled code systems as currently employed in assembly calculations. Finally, numerical tests are conducted using realistic SCALE assembly models with resonance self-shielding, neutron transport, and nuclides transmutation/depletion models representing the components of the coupled code system.

  1. Hybrid reduced order modeling for assembly calculations

    DOE PAGES

    Bang, Youngsuk; Abdel-Khalik, Hany S.; Jessee, Matthew A.; ...

    2015-08-14

    While the accuracy of assembly calculations has greatly improved due to the increase in computer power enabling more refined description of the phase space and use of more sophisticated numerical algorithms, the computational cost continues to increase which limits the full utilization of their effectiveness for routine engineering analysis. Reduced order modeling is a mathematical vehicle that scales down the dimensionality of large-scale numerical problems to enable their repeated executions on small computing environment, often available to end users. This is done by capturing the most dominant underlying relationships between the model's inputs and outputs. Previous works demonstrated the usemore » of the reduced order modeling for a single physics code, such as a radiation transport calculation. This paper extends those works to coupled code systems as currently employed in assembly calculations. Finally, numerical tests are conducted using realistic SCALE assembly models with resonance self-shielding, neutron transport, and nuclides transmutation/depletion models representing the components of the coupled code system.« less

  2. A thermodynamic model for calculating methane solubility, density and gas phase composition of methane-bearing aqueous fluids from 273 to 523 K and from 1 to 2000 bar

    NASA Astrophysics Data System (ADS)

    Duan, Zhenhao; Mao, Shide

    2006-07-01

    A thermodynamic model is presented to calculate methane solubility, liquid phase density and gas phase composition of the H 2O-CH 4 and H 2O-CH 4-NaCl systems from 273 to 523 K (possibly up to 573 K), from 1 to 2000 bar and from 0 to 6 mol kg -1 of NaCl with experimental accuracy. By a more strict theoretical approach and using updated experimental data, this model made substantial improvements over previous models: (1) the accuracy of methane solubility in pure water in the temperature range between 273 and 283 K is increased from about 10% to about 5%, but confirms the accuracy of the Duan model [Duan Z., Moller N., Weare J.H., 1992a. Prediction of methane solubilities in natural waters to high ionic strength from 0 to 250 °C and from 0 to 1600 bar. Geochim. Cosmochim. Acta56, 1451-1460] above 283 K up to 2000 bar; (2) the accuracy of methane solubility in the NaCl aqueous solutions is increased from >12% to about 6% on average from 273 K and 1 bar to 523 K and 2000 bar; (3) this model is able to calculate water content in the gas phase and liquid phase density, which cannot be calculated by previous models; and (4) it covers a wider range of temperature and pressure space. With a simple approach, this model is extended to predict CH 4 solubility in other aqueous salt solutions containing Na +, K +, Mg 2+, Ca 2+, Cl - and SO42-, such as seawater and geothermal brines, with excellent accuracy. This model is also able to calculate homogenization pressure of fluid inclusions (CH 4-H 2O-NaCl) and CH 4 solubility in water at gas-liquid-hydrate phase equilibrium. A computer code is developed for this model and can be downloaded from the website: www.geochem-model.org/programs.htm.

  3. Removal of Radioactive Nuclides by Multi-Functional Microcapsules Enclosing Inorganic Ion-Exchangers and Organic Extractants

    SciTech Connect

    Mimura, H.; Akiba, K.; Onodera, Y.

    2002-02-26

    The microcapsules enclosing two kinds of functional materials, inorganic ion-exchangers and organic extractants, were prepared by taking advantage of the high immobilization ability of alginate gel polymer. The fine powders of inorganic ion-exchanger and oil drops of extractant were kneaded with sodium alginate (NaALG) solution and the kneaded sol readily gelled in a salt solution of CaCl2, BaCl2 or HCl to form spherical gel particles. The uptake properties of various nuclides, 137Cs, 85Sr, 60Co, 88Y, 152Eu and 241Am, for thirty-four specimens of microcapsules in the presence of 10-1-10-4 M HNO3 were evaluated by the batch method. The distribution coefficient (Kd) of Cs+ above 103 cm3/g was obtained for the microcapsules enclosing CuFC or AMP. The Kd of Sr2+ around 102 cm3/g was obtained for the microcapsules containing clinoptilolite, antimonic acid, zeolite A, zeolite X or titanic acid. The microcapsules enclosing DEHPA exhibited relatively large Kd values of trivalent metal ions above 103 cm3/g; for example, the Kd values of Cs+, Sr2+, Co2+, Y3+, Eu3+ and Am3+ for a favorable microcapsule (CuFC/clinoptilolite/DEHPA/CaALG) were 1.1x104, 7.5x10, 1.1x10, 1.0x104, 1.4x104, 3.4x103 cm3/g, respectively. The uptake rates of Cs+, Y3+, Eu3+ and Am3+ for this microcapsule were rather fast; the uptake percentage above 90% was obtained after 19 h-shaking and the uptake equilibrium was attained within 1 d. The AMP/CaALG exhibited high uptake ability for Cs+ even after irradiation of 188 kGy, and DEHPA/CaALG microcapsule had similar Kd values of Cs+, Sr2+, Co2+, Y3+, Eu3+ and Am3+ ions before and after irradiation. The microcapsules with various shapes such as spherical, columnar, fibrous and filmy forms were easily prepared by changing the way of dipping kneaded sol into gelling salt solution. The microcapsules enclosing inorganic ion-exchangers and extractants have a potential possibility for the simultaneous removal of various radioactive nuclides from waste solutions.

  4. Data and software tools for gamma radiation spectral threat detection and nuclide identification algorithm development and evaluation

    NASA Astrophysics Data System (ADS)

    Portnoy, David; Fisher, Brian; Phifer, Daniel

    2015-06-01

    spectral data at 1 s time intervals, which represents data collected by a mobile system operating in a dynamic radiation background environment; and one that represents static measurements with a foreground spectrum (background plus source) and a background spectrum. These data include controlled variations in both Source Related Factors (nuclide, nuclide combinations, activities, distances, collection times, shielding configurations, and background spectra) and Detector Related Factors (currently only gain shifts, but resolution changes and non-linear energy calibration errors will be added soon). The software tools will allow the developer to evaluate the performance impact of each of these factors. Although this first implementation is somewhat limited in scope, considering only NaI-based detection systems and two application domains, it is hoped that (with community feedback) a wider range of detector types and applications will be included in the future. This article describes the methods used for dataset creation, the software validation/performance measurement tools, the performance metrics used, and examples of baseline performance.

  5. Glacial Erosion Rates from Bayesian Inversion of Cosmogenic Nuclide Concentrations in a Bedrock Core, Streaked Mtn., ME

    NASA Astrophysics Data System (ADS)

    Ploskey, Z. T.; Stone, J. O.

    2014-12-01

    Glacial erosion is an important source of sediment and could be an important coupling to glacier and ice sheet models that track sediment. However, glacial erosion is difficult to quantify, and models of glacial erosion can benefit from independent erosion rate estimates. Here we present the results of a Bayesian Markov chain Monte Carlo (MCMC) inversion of a cosmogenic nuclide (CN) geomorphic model for glacial erosion rates on a bedrock landform formerly eroded beneath the Laurentide ice sheet. The CN 10Be was measured in quartz to 8 m depth in a bedrock core from the summit of Streaked Mountain, ME. The accumulation of 10Be was modeled over multiple glacial cycles of alternating exposure and glacial erosion. This model was invertedfor glacial erosion rates and burial history using MCMC algorithms implemented in PyMC (Patil et al., 2010). This Bayesian approach allows us to incorporate prior constraints on ice cover history, including oxygen isotope records and radiometric dates, which is otherwise difficult to differentiate from erosion in rapidly eroding areas. We compare these results to depth profile and surface CN measurements elsewhere in Maine (Ploskey and Stone, 2013).The forward model of CN production used in the inversion is part of Cosmogenic (github.com/cosmolab/cosmogenic), an open-source Python-based software library we developed for modeling the growth and decay of in-situ CN inventories in rock during geomorphic evolution. It includes calibrated production rates for 10Be and 26Al in quartz and 36Cl in K-feldspar by both neutrons and muons, with more isotopic production pathways and material targets to be added in the future. Production rates are scaled to the site altitude and latitude using modular scaling schemes. Cosmogenic includes a variety of functions representing common geomorphic histories, and can be used to model any arbitrary exposure, erosion and burial history that can be defined as Python function.ReferencesPatil, A., D. Huard and C

  6. Hydrologic Nuclide Transport Models in Cyder, A Geologic Disposal Software Library - 13328

    SciTech Connect

    Huff, Kathryn D.

    2013-07-01

    Component level and system level abstraction of detailed computational geologic repository models have resulted in four rapid computational models of hydrologic radionuclide transport at varying levels of detail. Those models are described, as is their implementation in Cyder, a software library of interchangeable radionuclide transport models appropriate for representing natural and engineered barrier components of generic geology repository concepts. A proof of principle demonstration was also conducted in which these models were used to represent the natural and engineered barrier components of a repository concept in a reducing, homogenous, generic geology. This base case demonstrates integration of the Cyder open source library with the Cyclus computational fuel cycle systems analysis platform to facilitate calculation of repository performance metrics with respect to fuel cycle choices. (authors)

  7. Optical model methods of predicting nuclide production cross sections from heavy ion fragmentation

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Ramsey, C. R.; Tripathi, R. K.; Cucinotta, F. A.; Norbury, J. W.; Wilson, J. W. (Principal Investigator)

    1999-01-01

    Quantum mechanical optical potential methods for calculating inclusive isotope and element production cross sections from the fragmenting of heavy nuclei by intermediate- and high-energy protons and heavy ions are presented based upon a modified abrasion-ablation-FSI (frictional spectator interaction) collision model. The abrasion stage is treated as a quantum mechanical knockout process that leaves the residual prefragment in an excited state. Prefragment excitation energies are estimated using a combined liquid drop and FSI method. In ablation the prefragment deexcites by particle and photon emission to produce the final fragment. Contributions from electromagnetic dissociation to single nucleon removal cross sections are incorporated using a Weiszacker-Williams theory that includes electric dipole and electric quadrupole interactions. Estimates of elemental and isotopic production cross sections are in good agreement with published cross section measurements for a variety of projectile-target-beam energy combinations.

  8. PRODUCTION OF ALL THE r-PROCESS NUCLIDES IN THE DYNAMICAL EJECTA OF NEUTRON STAR MERGERS

    SciTech Connect

    Wanajo, Shinya; Sekiguchi, Yuichiro; Kiuchi, Kenta; Shibata, Masaru; Nishimura, Nobuya; Kyutoku, Koutarou

    2014-07-10

    Recent studies suggest that binary neutron star (NS-NS) mergers robustly produce heavy r-process nuclei above the atomic mass number A ∼ 130 because their ejecta consist of almost pure neutrons (electron fraction of Y {sub e} < 0.1). However, the production of a small amount of the lighter r-process nuclei (A ≈ 90-120) conflicts with the spectroscopic results of r-process-enhanced Galactic halo stars. We present, for the first time, the result of nucleosynthesis calculations based on the fully general relativistic simulation of a NS-NS merger with approximate neutrino transport. It is found that the bulk of the dynamical ejecta are appreciably shock-heated and neutrino processed, resulting in a wide range of Y {sub e} (≈0.09-0.45). The mass-averaged abundance distribution of calculated nucleosynthesis yields is in reasonable agreement with the full-mass range (A ≈ 90-240) of the solar r-process curve. This implies, if our model is representative of such events, that the dynamical ejecta of NS-NS mergers could be the origin of the Galactic r-process nuclei. Our result also shows that radioactive heating after ∼1 day from the merging, which gives rise to r-process-powered transient emission, is dominated by the β-decays of several species close to stability with precisely measured half-lives. This implies that the total radioactive heating rate for such an event can be well constrained within about a factor of two if the ejected material has a solar-like r-process pattern.

  9. Neutron core excitations in the N=126 nuclide {sup 210}Po

    SciTech Connect

    Dracoulis, G. D.; Lane, G. J.; Davidson, P. M.; Kibedi, T.; Nieminen, P.; Maier, K. H.; Watanabe, H.; Byrne, A. P.; Wilson, A. N.

    2008-03-15

    Excited states above the 16{sup +} isomer in {sup 210}Po have been identified using time-correlated {gamma}-ray spectroscopy techniques and the {sup 204}Hg({sup 13}C,3n{alpha}){sup 210}Po reaction. States up to {approx}27({Dirac_h}/2{pi}) have been identified, including an isomer at 8074 keV with a mean life of 13(2) ns. Among the new states, a candidate for the 17{sup +} state obtained from maximal coupling of the {pi}[h{sub 9/2}i{sub 13/2}]{sub 11{sup -}} valence proton configuration and the {nu}[p{sub 1/2}{sup -1}i{sub 11/2}]{sub 6{sup -}} neutron core excitation has been identified. This and other results are compared with semiempirical shell-model calculations that predict that single core excitations from the i{sub 13/2} neutron orbital and double core excitations out of the p{sub 1/2} and f{sub 5/2} orbitals, populating the g{sub 9/2},i{sub 11/2}, and j{sub 15/2} orbitals above the N=126 shell, will compete in energy. Good agreement is obtained for the lower states but there are systematic discrepancies at high spins including the absence of states that are calculated to lie low in the spectrum, implying uncertainties for configurations associated either with the i{sub 13/2} neutron hole or double core excitations.

  10. Production of All the r-process Nuclides in the Dynamical Ejecta of Neutron Star Mergers

    NASA Astrophysics Data System (ADS)

    Wanajo, Shinya; Sekiguchi, Yuichiro; Nishimura, Nobuya; Kiuchi, Kenta; Kyutoku, Koutarou; Shibata, Masaru

    2014-07-01

    Recent studies suggest that binary neutron star (NS-NS) mergers robustly produce heavy r-process nuclei above the atomic mass number A ~ 130 because their ejecta consist of almost pure neutrons (electron fraction of Y e < 0.1). However, the production of a small amount of the lighter r-process nuclei (A ≈ 90-120) conflicts with the spectroscopic results of r-process-enhanced Galactic halo stars. We present, for the first time, the result of nucleosynthesis calculations based on the fully general relativistic simulation of a NS-NS merger with approximate neutrino transport. It is found that the bulk of the dynamical ejecta are appreciably shock-heated and neutrino processed, resulting in a wide range of Y e (≈0.09-0.45). The mass-averaged abundance distribution of calculated nucleosynthesis yields is in reasonable agreement with the full-mass range (A ≈ 90-240) of the solar r-process curve. This implies, if our model is representative of such events, that the dynamical ejecta of NS-NS mergers could be the origin of the Galactic r-process nuclei. Our result also shows that radioactive heating after ~1 day from the merging, which gives rise to r-process-powered transient emission, is dominated by the β-decays of several species close to stability with precisely measured half-lives. This implies that the total radioactive heating rate for such an event can be well constrained within about a factor of two if the ejected material has a solar-like r-process pattern.

  11. SUBGR: A Program to Generate Subgroup Data for the Subgroup Resonance Self-Shielding Calculation

    SciTech Connect

    Kim, Kang Seog

    2016-06-06

    The Subgroup Data Generation (SUBGR) program generates subgroup data, including levels and weights from the resonance self-shielded cross section table as a function of background cross section. Depending on the nuclide and the energy range, these subgroup data can be generated by (a) narrow resonance approximation, (b) pointwise flux calculations for homogeneous media; and (c) pointwise flux calculations for heterogeneous lattice cells. The latter two options are performed by the AMPX module IRFFACTOR. These subgroup data are to be used in the Consortium for Advanced Simulation of Light Water Reactors (CASL) neutronic simulator MPACT, for which the primary resonance self-shielding method is the subgroup method.

  12. Mass measurements on stable nuclides in the rare-earth region with the Penning-trap mass spectrometer TRIGA-TRAP

    SciTech Connect

    Ketelaer, J.; Audi, G.; Beyer, T.; Blaum, K.; Block, M.; Dworschak, M.; Herfurth, F.; Cakirli, R. B.; Casten, R. F.; Droese, C.; Eberhardt, K.; Eibach, M.; Smorra, C.; Minaya Ramirez, E.; Nagy, Sz.; Neidherr, D.; Noertershaeuser, W.; Wang, M.

    2011-07-15

    The masses of 15 stable nuclides in the rare-earth region have been measured with the Penning-trap mass spectrometer TRIGA-TRAP. This is the first series of absolute mass measurements linking these nuclides to the atomic-mass standard {sup 12}C. Previously, nuclear reaction studies almost exclusively determined the literature values of these masses in the Atomic-Mass Evaluation. The TRIGA-TRAP results show deviations on the order of 3-4 standard deviations from the latest published values of the Atomic-Mass Evaluation 2003 for some cases. However, the binding-energy differences that are important for nuclear structure studies have been confirmed and improved. The new masses are discussed in the context of valence proton-neutron interactions using double differences of binding energies, {delta}V{sub pn}(Z,N).

  13. TRENDS (Transport and Retention of Nuclides in Dominant Sequences): A code for modeling iodine behavior in containment during severe accidents

    SciTech Connect

    Weber, C.F.; Beahm, E.C.; Kress, T.S.; Daish, S.R.; Shockley, W.E.

    1989-01-01

    The ultimate aim of a description of iodine behavior in severe LWR accidents is a time-dependent accounting of iodine species released into containment and to the environment. Factors involved in the behavior of iodine can be conveniently divided into four general categories: (1) initial release into containment, (2) interaction of iodine species in containment not directly involving water pools, (3) interaction of iodine species in, or with, water pools, and (4) interaction with special systems such as ice condensers or gas treatment systems. To fill the large gaps in knowledge and to provide a means for assaying the iodine source term, this program has proceeded along two paths: (1) Experimental studies of the chemical behavior of iodine under containment conditions. (2) Development of TRENDS (Transport and Retention of Nuclides in Dominant Sequences), a computer code for modeling the behavior of iodine in containment and its release from containment. The main body of this report consists of a description of TRENDS. These two parts to the program are complementary in that models within TRENDS use data that were produced in the experimental program; therefore, these models are supported by experimental evidence that was obtained under conditions expected in severe accidents. 7 refs., 1 fig., 2 tabs.

  14. Prompt neutron emission multiplicity distributions and average values, /bar char/. nu. , at 2200 meter per second for the fissile nuclides

    SciTech Connect

    Holden, N.E.; Zucker, M.S.

    1988-01-01

    The prompt neutron emission multiplicity distribution, P/sub nu/ is of interest for methods of self-calibration and for auto-correlation to assay fissionable material for nuclear safeguards. /bar char/..nu.., the average value of P/sub nu/, is of interest at neutron thermal energies since it is used as a normalizing point for energy dependent values of /bar char/..nu... Values of P/sub nu/ and /bar char/..nu.. have been determined at the standard neutron energy of 0.0253 ev for the neutron induced fission of the four fissile nuclides, /sup 233,235/U, and /sup 239,241/Pu. Revised /bar char/..nu.. values have been obtained by re-evaluating /bar char/..nu.. experiments measured at 2200 meter/second relative to the /bar char/..nu.. from the spontaneous fission of /sup 252/Cf. These revised values of /bar char/..nu.. been used to renormalize the measured P/sub nu/ values. The revised values of /bar char/..nu.. are all about 1/4% to 1/2% smaller than the corresponding values of ENDF/B-V. 25 refs., 4 tabs.

  15. Pliocene Cosmogenic Nuclide Burial Ages of the Nenana Gravel: Progress in Dating and Implications for Alaska Range Evolution

    NASA Astrophysics Data System (ADS)

    Goehring, B. M.; Bemis, S. P.; Ward, D.; Caffee, M. W.; Sortor, R. N.

    2015-12-01

    The Nenana Gravel is an up to 1.2 km thick foreland basin deposit that spans the north flank of the Alaska Range. It is uplifted relative to the active foreland basin to the north. It is also deformed to various degree dependent on its location within the northern Alaska Range thrust system. Because this foreland basin sequence records the unroofing and northward propagation of the Alaska Range, direct dating of the Nenana Gravel, especially over wide spatial distribution along the Alaska Range, will substantially advance our understanding of the style and timing of deformation of the Alaska Range. At present though, age estimates for the Nenana Gravel are limited to a single maximum limiting age and uncertain minimum limiting age with no little or no insight as to the spatial variation in Nenana Gravel deposition timing. We present the first direct dates of deposition ages of the Nenana Gravel using cosmogenic nuclide burial dating. Results indicate that deposition of the Nenana Gravel began ca. 6.5 Ma, in stratigraphic agreement with a maximum limiting tephra age from the underlying Usibelli Group. Additional samples from the Nenana Gravel basal contact and higher in the section are presently underway. The resultant burial ages are amongst the oldest 26Al-10Be burial ages ever produced and highlight the potential of the method to directly date sediments in the Pliocene, particularly given recent advancements in the accelerator mass spectrometry measurement of 26Al/27Al isotope ratios.

  16. Terrestrial cosmogenic nuclide surface exposure dating of the oldest glacial successions in the Himalayan orogen: Ladakh Range, northern India

    USGS Publications Warehouse

    Owen, L.A.; Caffee, M.W.; Bovard, K.R.; Finkel, R.C.; Sharma, M.C.

    2006-01-01

    Terrestrial cosmogenic nuclide surface exposure dating of moraine boulders and alluvial fan sediments define the timing of five glacial advances over at least the last five glacial cycles in the Ladakh Range of the Transhimalaya. The glacial stages that have been identified are: the Indus Valley glacial stage, dated at older than 430 ka; the Leh glacial stage occurring in the penultimate glacial cycle or older; the Karglacial stage, occurring during the early part of the last glacial cycle; the Bazgo glacial stage, at its maximum during the middle of the last glacial cycle; and the early Holocene Khalling glacial stage. The exposure ages of the Indus Valley moraines are the oldest observed to date throughout the Himalayan orogen. We observe a pattern of progressively more restricted glaciation during the last five glacial cycles, likely indicating a progressive reduction in the moisture supply necessary to sustain glaciation. A possible explanation is that uplift of Himalayan ranges to the south and/or of the Karakoram Mountains to the west of the region may have effectively blocked moisture supply by the south Asian summer monsoon and mid-latitude westerlies, respectively. Alternatively, this pattern of glaciation may reflect a trend of progressively less extensive glaciation in mountain regions that has been observed globally throughout the Pleistocene. ?? 2006 Geological Society of America.

  17. G4MoNA - A Geant4 Simulation for unbound nuclides detected with MoNA/LISA

    NASA Astrophysics Data System (ADS)

    Gueye, Paul; Freeman, Jessica; Frank, Nathan; MoNA Collaboration

    2017-01-01

    The MoNA Collaboration has conducted a plethora of experiments to study unbound nuclei near the neutron dripline using the invariant mass technique since 2005. These experiments used a variety of secondary beams from the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory. The experimental setup consists of a large gap superconducting Sweeper magnet for charged fragments separation and the MoNA/LISA neutron detector arrays for neutron detection. Recently, a multi-layered Si/Be segmented target consisting of three 700 mg/cm2 thick 9Be slabs and four 140 μ m Si detectors were added to the setup. This target improves the resolution of the reconstructed decay energy spectra of the unbound nuclides. The Geant4 Monte Carlo simulation toolkit was used to develop a complete realistic model of the setup including a new class to treat the decay of unbound nuclei, the Si/Be segmented target, the MoNA/LISA and the charged fragments detector systems. Comparison between simulated and experimental data will be presented. DoENNSA - DE-NA0000979.

  18. Theoretical calculations and analysis for n + 6Li reaction

    NASA Astrophysics Data System (ADS)

    Tao, Xi; Wang, Jimin; Chen, Guochang; Shen, Qingbiao

    2017-09-01

    R-matrix theory is an important methodology for applications on light, medium and heavy mass nuclides nuclear reaction in the resonance energy range. Full R-matrix formalism contains the diagonal elements of the energy levels matrix and it is a rigorous theory. Because of different assumptions and approximations, many kinds of R-matrix derived methods are obtained. The new R-matrix code FDRR is presented and includes 4 kinds of R-matrix applications. It can be used for calculating integral cross sections and angular distributions of 2-bodies reactions. The cross sections and angular distributions of n+ 6Li reaction are calculated and analyzed by FDRR code. The results are in good agreement with experimental data below 20 MeV.

  19. Transmutation calculations for the accelerator transmutation of waste (ATW) program

    SciTech Connect

    Wilson, W.B.; Arthur, E.D.; Bowman, C.D.; Engel, L.N.; England, T.R.; Hughes, H.G.; Lisowski, P.W.; Perry, R.T.

    1991-01-01

    The disposal of radioactive waste by the transmutation of long-lived radionuclides is being considered; now using neutrons produced with an intense beam of 1.6-GeV protons on a Pb-Bi target. Study teams have been active in the areas of accelerator design, beam transport, radiation transport, transmutation, fluid flow and heat transfer, process chemistry and system analyses. Work is of a preliminary and developmental nature. Here we describe these preliminary efforts in transmutation calculations; the tools developed, status of basic nuclear data, and some early results. These calculations require the description of the intensity and spectrum of neutrons produced by the beam, the distribution of nuclides produced in the medium-energy reactions, the transport of particles produced by the beam, the transmutation of the target materials and transmutation products, and the decay properties of the inventory of radionuclides produced.

  20. Nuclear-decay studies of neutron-rich rare-earth nuclides

    SciTech Connect

    Chasteler, R.M. . Dept. of Chemistry Lawrence Berkeley Lab., CA )

    1990-04-26

    Neutron-rich rare-earth nuclei were produced in multinucleon transfer reactions of {sup 170}Er and {sup 176}Yb projectiles on {sup nat}W targets at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decays properties studied at the on-line mass separation facility OASIS. Two unknown isotopes, {sup 169}Dy (t {sub 1/2} {equals} 39 {plus minus} 8 s) and {sup 174}Er(t{sub 1/2} {equals} 3.3 {plus minus} 0.2 m) were discovered and their decay characteristics determined. The decay schemes for two previously identified isotopes, {sup 168}Dy (t{sub 1/2} {equals} 8.8 {plus minus} 0.3 m) and {sup 171}Ho (t{sub 1/2} {equals} 55 {plus minus} 3 s), were characterized. Evidence for a new isomer of 3.0 m {sup 168}Ho{sup g}, {sup 168}Ho{sup m} (t{sub 1/2} {equals} 132 {plus minus} 4 s) which decays by isomeric transition (IT) is presented. Beta particle endpoint energies were determined for the decay of {sup 168}Ho{sup g}, {sup 169}Dy, {sup 171}Ho, and {sup 174}Er, the resulting Q{beta}-values are: 2.93 {plus minus} 0.03, 3.2 {plus minus} 0.3, 3.2 {plus minus} 0.6, and 1.8 {plus minus} 0.2 MeV, respectively. These values were compared with values calculated using recent atomic mass formulae. Comparisons of various target/ion source geometries used in the OASIS mass separator facility for these multinucleon transfer reactions were performed. 73 refs., 40 figs., 11 tabs.

  1. The production of cosmogenic nuclides by GCR-particles for 2 pi exposure geometries

    NASA Astrophysics Data System (ADS)

    Leya, I.; Neumann, S.; Wieler, R.; Michel, R.

    2001-11-01

    We present a purely physical model for the calculation of depth dependent production rates in 2 pi exposure geometries by galactic cosmic rays (GCR). Besides the spectra of primary and secondary particles and the excitation functions of the underlying nuclear reactions, the model is based on the integral number of GCR particles in the lunar orbit. We derived this value from adjusting modeled depth profiles for 10Be, 26Al, and 53Mn to measured data from the Apollo 15 drill core. The J0,GCR-value of 4.54 cm-2 s-1 and the solar modulation parameter of M = 490 MeV determined this way for 1 AU is in reasonable agreement with the J0,GCR-value derived recently for the meteoroid orbits (Leya et al., 2000b). We also show that the mean GCR proton spectrum in the lunar orbit has not changed substantially over about the last 10 Myr. For the major target elements we present depth dependent production rates for 10Be, 14C, 26Al, 36Cl and 53Mn, as well as for the rare gas isotopes 20,21,22Ne. In addition we present production rates for 36,38Ar from Fe and Ni. The new results are consistent with the data for stony meteoroids presented recently by our group (Leya et al., 2000b), but for the rare gas isotopes the new production rates sometimes differ significantly from earlier estimates. The applicability of the 22Ne/21Ne ratio as a shielding parameter is also discussed.

  2. Sensitivity of p-nuclei abundance calculations to statistical model parameters

    NASA Astrophysics Data System (ADS)

    Roach, Brandon; Simon, Anna

    2017-01-01

    Many reactions relevant to astrophysics involve nuclei far from stability, and their cross sections must therefore be calculated numerically for input into large-scale stellar nucleosynthesis calculations. Recent work, especially regarding p-process nucleosynthesis, has shown that the observed astrophysical abundances of certain nuclides differ by almost a factor of 10 from those predicted by network calculations using accepted reaction rates. Additionally, significant differences between calculated abundances when using different versions of these rates have been obtained. We therefore present the abundances of p-nuclei calculated using the open-source NucNet Tools code for a 25 solar mass type II supernova model, incorporating reaction cross sections calculated using the statistical-model code TALYS using several α optical potentials and γ-strength functions. This work is supported by the NSF under Grant Numbers PHY-1614442 and PHY-1430152 (JINA-CEE).

  3. From source to sink with in situ cosmogenic nuclides: Modern to late Holocene denudation rates and sediment fluxes in the Po basin

    NASA Astrophysics Data System (ADS)

    Wittmann, Hella; Malusà, Marco; Resentini, Alberto; Garzanti, Eduardo; Niedermann, Samuel

    2017-04-01

    Cosmogenic nuclides are now established as an integral tool of Earth surface science, providing reliable measures of landscape change. Applications of in situ-produced nuclides to lowland basins, where sediment undergoes storage and deposition, are however still rare. Recently, it was shown for large cratonic river basins that cosmogenic nuclides can provide an integrated approach insensitive to a range of geological sources of bias thereby tracing signals from upstream mountainous areas to the lowlands (summary given in [1]). Given these advances of the method, we can proceed with the application to a geologically complex subsiding foreland basin. In the Po basin, we constrained the long-term sediment delivery from source to deltaic sink using sediment fluxes from in situ 10Be-derived denudation rates and compared these to published short-term estimates from gauging. From the comparison of 10Be nuclide data measured upstream of dam influence to those measured downstream of major dams, we find that the average 10Be signal is not significantly modified. In the lowland reaches, we find that the average 10Be concentration is only marginally modified by floodplain processes, as 26Al/10Be ratios do not show differential decay due to burial. The close similarity in 10Be concentrations from the sources to the Po lowland sink suggests that LGM denudation rates prior to sediment trapping in periglacial lakes were similar to today's, as the sediment now contained in the Po lowlands must have been eroded from the orogen and deposited in the lowlands prior to lake formation. Todaýs sediment in the Alpine and Apenninic source areas erodes at 10Be-derived rates ranging from 0.1-1.5 mm/yr in the Alpine and from 0.25-0.5 mm/yr in the Apenninic source areas. The highest 10Be-derived denudation rates are found in the western Central Alps (1.5 mm/yr), where also recent uplift rates are among the highest. From these data, we constrain a total cosmogenic-derived sediment flux leaving

  4. Calculation of the radionuclides in PWR spent fuel samples for SFR experiment planning.

    SciTech Connect

    Naegeli, Robert Earl

    2004-06-01

    This report documents the calculation of radionuclide content in the pressurized water reactor (PWR) spent fuel samples planned for use in the Spent Fuel Ratio (SPR) Experiments at Sandia National Laboratories, Albuquerque, New Mexico (SNL) to aid in experiment planning. The calculation methods using the ORIGEN2 and ORIGEN-ARP computer codes and the input modeling of the planned PWR spent fuel from the H. B. Robinson and the Surry nuclear power plants are discussed. The safety hazards for the calculated nuclide inventories in the spent fuel samples are characterized by the potential airborne dose and by the portion of the nuclear facility hazard category 2 and 3 thresholds that the experiment samples would present. In addition, the gamma ray photon energy source for the nuclide inventories is tabulated to facilitate subsequent calculation of the direct and shielded dose rates expected from the samples. The relative hazards of the high burnup 72 gigawatt-day per metric ton of uranium (GWd/MTU) spent fuel from H. B. Robinson and the medium burnup 36 GWd/MTU spent fuel from Surry are compared against a parametric calculation of various fuel burnups to assess the potential for higher hazard PWR fuel samples.

  5. Contribution of Paleomagnetic and Cosmogenic Nuclide Production Records to Solve the Question of Orbital Constraint on the Geodynamo

    NASA Astrophysics Data System (ADS)

    Thouveny, N.; Ménabréaz, L.; Bourles, D. L.; Demory, F.; Guillou, V.; Arnold, M.; Magorb Team

    2013-05-01

    The contribution of axial precession to the geodynamo energy budget recently rebounded with the demonstrations through theoretical and experimental studies that its amount of energy had been underestimated, while on the contrary the energy required to disturb the geodynamo was overestimated (e.g. Vanyo, 2004, Roberts et Wu, 2005, Tilgner 2005). Paleomagnetic tests of such an hypothesis remain yet highly controversial because relative paleointensity reconstructions are suspected of paleoenvironmental biases. Many available indicators [i) depositional remanent magnetization of sediment (paleodirections and paleointensity), ii) magnetization of the deep sea floor basalts, iii) geochemical records of cosmogenic nuclides production rates] however converge to produce a robust series of geomagnetic dipole lows related to paleomagnetic excursions of the last Ma. These series evidence periodicities in the 30 kyr-120 kyr range and present phase relationships with obliquity variations and δ18O records. Yet, such paleomagnetic time series are presently not precise and complete enough to firmly validate such fundamental but still hypothetic relationship. To further contribute solving this issue, the MAG-ORB project, funded for a 4 years period by the French Agence Nationale de la Recherche, aims at reconstructing the time series of the geomagnetic dipole lows over the last 2 Ma using paleomagnetism coupled with cosmogenic nuclide 10Be and lithogenic 9Be isotopes measurements on sedimentary cores from mid and low latitudes, i.e. where the geomagnetic modulation of the cosmic ray penetration is the most efficient. New results (Ménabréaz et al., 2011; 2012; Ménabréaz, 2012) confirm and complete former results (Carcaillet et al., 2003; 2004) to demonstrate that over the last 1.2 Ma the excursions and reversals, and their respective relative paleointensity lows, are accompanied by significant enhancements of the cosmogenic 10Be production rate, pointing out a global collapse of

  6. Thermodynamic Calculations for Complex Chemical Mixtures

    NASA Technical Reports Server (NTRS)

    Mcbride, B. J.

    1986-01-01

    General computer program, CECTRP, developed for calculation of thermodynamic properties of complex mixtures with option to calculate transport properties of these mixtures. Free-energy minimization technique used in equilibrium calculation. Rigorous equations used in transport calculations. Program calculates equilibrium compositions and corresponding thermodynamic and transport properties of mixtures. CECTRP accommodates up to 24 reactants, 20 elements, and 600 products, 400 of which are condensed. Written in FORTRAN IV for any large computer system.

  7. Extracting dynamic topography from river profiles and cosmogenic nuclide geochronology in the Middle Atlas and the High Plateaus of Morocco

    NASA Astrophysics Data System (ADS)

    Pastor, Alvar; Babault, Julien; Owen, Lewis A.; Teixell, Antonio; Arboleya, María-Luisa

    2015-11-01

    The Moulouya river system has intensely eroded the Arhbalou, Missour, and Guercif Neogene foreland basins in northeastern Morocco, having changed from net aggradation during the Miocene-early Pliocene to net incision punctuated by alluvial fan deposition at late Pliocene or early Quaternary time. This region as a whole has experienced mantle-driven, surface uplift (dynamic topography) since the late Cenozoic, being locally affected by uplift due to crustal shortening and thickening of the Middle Atlas too. Knickpoints located along the major streams of the Moulouya fluvial network, appear on both the undeformed margins of the Missour and Guercif foreland basins (High Plateaus), as well as along the thrust mountain front of the southern Middle Atlas, where they reach heights of 800-1000 m. 500-550 m of the knickpoint vertical incision might be explained by long-wavelength mantle-driven dynamic surface uplift, whereas the remaining 450-500 m in the southern Middle Atlas front and 200-300 m in the northeastern Middle Atlas front seem to be thrust-related uplift of the Jebel Bou Naceur. Be-10 terrestrial cosmogenic nuclides have been used to date two Quaternary river terraces in the Chegg Ard valley at 62 ± 14 ka and 411 ± 55 ka. The dated terraces allow the incision rates associated with the frontal structures of the Middle Atlas to be estimated at ~ 0.3 mm yr- 1. Furthermore, these ages have served to evaluate mantle-driven regional surface uplift since the middle Pleistocene in the central Missour basin, yielding values of ~ 0.1-0.2 mm yr- 1.

  8. Can cosmogenic nuclides (36Cl) unravel the timing of dislocation of tsunami blocks on Bonaire (Leeward Antilles)?

    NASA Astrophysics Data System (ADS)

    Engel, Max; Rixhon, Gilles; Brückner, Helmut; May, S. Matthias; Binnie, Steve; Dunai, Tibor J.

    2013-04-01

    On Bonaire (Leeward Antilles) and rocky coasts worldwide, high-energy wave events (tsunamis, storms) dislocate coarse-clast deposits (Engel and May, 2012). Using these onshore blocks and boulders to derive ages for the most powerful events on millennial scales is still a major challenge. We apply terrestrial cosmogenic nuclides (TCN), in particular 36Cl, in case of the largest blocks in order to directly date the transport event(s), i.e. the inferred tsunami(s). This dating method has hitherto been disregarded in the coastal environment, particularly in the context of block transport. The following characteristics of the blocks are fundamental for the success of the presented dating approach: (1) due to the lithology (aragonite, calcite), concentration measurements of 36Cl are performed; (2) only large and thick boulders and blocks (>50 t, >2 m thickness) for which tsunami transport was inferred (Engel and May, 2012) were sampled; (3) since the boulders stem from the edge of the coral reef platform, they had been exposed to cosmic radiation prior to the transport event(s) and had already accumulated a certain amount of TCN. To avoid this problem of inheritance, we only sampled the thickest clasts, and those having experienced a 180° overturn during transport; thus, having exposed a "blank" side to cosmic rays only since the event. The complete overturn is attested by the presence of inactive rock pools in upside-down position and bioerosive notches. Engel, M., and May, S. M.: Bonaire's boulder fields revisited: Evidence for Holocene tsunami impact on the Leeward Antilles, Quat. Sci. Rev., 54, 126-141, 2012.

  9. New Insights on Long Term Geomagnetic Moment Variation from Cosmogenic Nuclide and Paleointensity Signatures along Ocean Sediment Cores.

    NASA Astrophysics Data System (ADS)

    Thouveny, N.; Bourles, D. L.; Valet, J. P.; Bassinot, F. C.; Ménabréaz, L.; Simon, Q.; Demory, F.; Valery, G.; Vidal, L.; Beaufort, L.; de Garidel-Thoron, T.

    2015-12-01

    Some numerical and experimental simulations suggest that precession might supply enough power to influence planetary dynamos. The demonstration of a causal relationship between the Earth's orbital motion and variations of the geomagnetic field intensity, would open interesting perspective for modelling the past and future geomagnetic field behaviour and its eventual relationships to past and future orbitally constrained, climatic changes. Although pristine geomagnetic signals can be extracted by filtering and stacking multiple normalized intensity records, the reconstruction of high resolution geomagnetic field variations still raises questions. Namely, significant variance at orbital frequencies in relative paleointensity (RPI) records are generally considered as clues of residual contamination by paleoclimatically induced variations of magnetic carriers size ranges or mineralogy. Such questions can be adressed using other indicators of the geomagnetic dipole moment variation, such as the cosmogenic production modulated by the magnetospheric shielding. During the MAGORB project (ANR-09-BLAN-053-001) cosmogenic nuclide geochemistry, d18O, and paleomagnetic records were constructed along thick clayey-carbonate sequences deposited in the equatorial pacific and indian oceans over the last million of years. Authigenic 10Be/9Be ratio and RPI variations generally exhibit similar ranges of oscillations. However significant offsets appear between some RPI lows and their corresponding 10Be/9Be peaks, suggesting delayed lock-in of the remanent magnetization. After transfer on time scales the new geomagnetic moment series can be compared with the PISO-1500 and SINT-2000 stacks, and with the 10Be ice core record of EPICA Dome C. These new authigenic 10Be/9Be ratio records provide new opportunities to: 1) assess the validity of high resolution RPI records, 2) evaluate address the question of the presence of orbital periods in the paleo-field geomagnetic spectrum, and 3) to

  10. Insights on the post-seismic geomorphological response to the 2008 Wenchuan Earthquake from detrital cosmogenic nuclides data

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Godard, Vincent; Liu-Zeng, Jing; Scherler, Dirk; Xu, Chong; Xu, Quiang; Xie, Kejia; Bellier, Olivier; Ansberque, Claire; de Sigoyer, Julia; Aster Team

    2016-04-01

    In high-relief mountain ranges bounded by reverse faults, large-magnitude earthquakes can contribute to topographic growth by co- and inter-seismic surface uplift of the hanging wall; meanwhile, earthquakes can also lower relief by causing erosion through extensive landslides. Quantifying evacuation process of co-seismic landslides material is central to our understanding of mass redistribution at the earth surface and the evolution of active mountain ranges. The 2008 Mw 7.9 Wenchuan earthquake in the Longmen Shan range of eastern Tibet provides a valuable opportunity to evaluate such direct impact. Cosmogenic nuclides concentrations in river sands are diluted by the input of low-concentration landslide debris materials after the earthquake (West et al., 2014), and we document the evolution 10Be concentrations in quartz for several years after the Wenchuan earthquake to trace the routing processes of co-seismic landslides. Over the 2008-2013 period we collected river sand samples at 19 locations annually along the rivers that flow through the rupture zone. When compared with published pre-earthquake data, our results show that the 10Be concentration in river sand declined dramatically after the earthquake at all sampling sites. Meanwhile, multi-year time series of 10Be concentration at single sites present roughly constant level of dilution with moderate fluctuations. Our analyses indicate that the 10Be dilution amplitude is closely controlled by local catchment slope and landslide density, rather than by the location of landslides with respect to sampling sites. The perturbation we observed for 10Be concentrations in the 0.25~1 mm size fraction appears to be sustained over the timescale of our survey with no clear relaxation, which is consistent with independent results from suspended sediment analysis (Wang et al., 2015).

  11. Sensitivity of MCNP5 calculations for a spherical numerical benchmark problem to the angular scattering distributions for deuterium

    SciTech Connect

    Kozier, K. S.

    2006-07-01

    This paper examines the sensitivity of MCNP5 k{sub eff} results to various deuterium data files for a simple benchmark problem consisting of an 8.4-cm radius sphere of uranium surrounded by an annulus of deuterium at the nuclide number density corresponding to heavy water. This study was performed to help clarify why {Delta}k{sub eff} values of about 10 mk are obtained when different ENDF/B deuterium data files are used in simulations of critical experiments involving solutions of high-enrichment uranyl fluoride in heavy water, while simulations of low-leakage, heterogeneous critical lattices of natural-uranium fuel rods in heavy water show differences of <1 mk. The benchmark calculations were performed as a function of deuterium reflector thickness for several uranium compositions using deuterium ACE files derived from ENDF/B-VII.b1 (release beta 1), ENDF/B-VI.4 and JENDL-3.3, which differ primarily in the energy/angle distributions for elastic scattering <3.2 MeV. Calculations were also performed using modified ACE files having equiprobable cosine bin values in the centre-of-mass reference frame in a progressive manner with increasing energy. It was found that the {Delta}k{sub eff} values increased with deuterium reflector thickness and uranium enrichment. The studies using modified ACE files indicate that most of the reactivity differences arise at energies <1 MeV; hence, this energy range should be given priority if new scattering distribution measurements are undertaken. (authors)

  12. Chemical and isotopic compositions in acid residues from various meteorites

    NASA Technical Reports Server (NTRS)

    Kano, N.; Yamakoshi, K.; Matsuzaki, H.; Nogami, K.

    1993-01-01

    We are planning to carry out systematic isotopic investigations of Ru, Mg, etc., in primordial samples. The investigations will be pursued in the context of a study of the pre-history of the solar system. It is hoped that the study will yield direct evidence for processes of nucleosynthesis in the pre-solar stage and detection of extinct radioactive nuclides. In this paper, we present the results of chemical compositions of acid residues obtained from three types of meteorites: Canyon Diablo (IA), Allende (CV3), and Nuevo Mercuro (H5); and the preliminary results of Ru isotopic compositions.

  13. Li and B isotopic variations in an Allende CAI: Evidence for the in situ decay of short-lived 10Be and for the possible presence of the short-lived nuclide 7Be in the early solar system

    NASA Astrophysics Data System (ADS)

    Chaussidon, Marc; Robert, François; McKeegan, Kevin D.

    2006-01-01

    distributions occurred. Li and Be concentrations measured in different analytical spots are compared with those predicted by using experimentally determined partition coefficients according to a model of closed-system crystallization of the CAI melt. These criteria show that 56% of the spots in melilite, 38% in anorthite, and 8% in fassaite suffered post-crystallization perturbations of Li and/or Be distributions. In the remaining spots, which do not show obvious indication of redistribution of Li or Be, the 7Li/ 6Li isotopic variations (corrected for GCR exposure) are positively correlated with 9Be/ 6Li suggesting the in situ decay of now-extinct 7Be. The derived isochron implies that at the time of its formation, the CAI melt had a 7Be/ 9Be ratio of 0.0061 ± 0.0013 and a 7Li/ 6Li ratio of 11.49 ± 0.13. In contrast, all the spots in 3529-41, which do show evidence for post-magmatic redistribution of Li and Be, have relatively constant 7Li/ 6Li, averaging 11.72 ± 0.56, which is consistent with mass balance calculations for Li isotopic homogenization in the CAI after the decay of 7Be. The incorporation of live 7Be in 3529-41 requires, because of the very short half-life of this nuclide (53 days), that it be produced essentially contemporaneously with the formation of the CAI. Therefore, the irradiation processes responsible for production of 7Be must have occurred within the solar accretion disk. Calculations developed in the framework of the x-wind model [Gounelle, M., Shu, F.H., Shang, H., Glassgold, A.E., Rehm, E.K., Lee, T., 2004. The origin of short-lived radionuclides and early Solar System irradiation (abstract). Lunar Planet. Sci.35, 1829] reproduce the 7Be and 10Be abundances observed in 3529-41. The correlated presence of 7Be and 10Be in 3529-41 is thus a strong argument that 10Be, which is observed rather ubiquitously in CAIs, is also a product of irradiation in the early solar system, as might be a significant fraction of other short-lived radionuclides observed

  14. Cosmogenic nuclide and uranium-series dating of old, high shorelines in the western Great Basin, USA

    USGS Publications Warehouse

    Kurth, G.; Phillips, F.M.; Reheis, M.C.; Redwine, J.L.; Paces, J.B.

    2011-01-01

    Closed-basin pluvial lakes are sensitive recorders of effective moisture, and they provide a terrestrial signal of climate change that can be compared to marine and ice records of glacial-interglacial cycles. Although the most recent deep-lake cycle in the western Great Basin (at ca. 16 ka) has been studied intensively, comparatively little is known about the longer-term Quaternary lacustrine history of the region. Lacustrine features higher than those of the most recent highstand have been discovered in many locations throughout the western Great Basin. Qualitative geomorphic and soil studies of shoreline sequences above the latest Pleistocene level suggest that their ages increase as a function of increasing altitude. The results of cosmogenic nuclide dating using chlorine-36 depth profiles from three sites in Nevada (Walker Lake, Columbus Salt Marsh, and Newark Valley), combined with uranium-series and radiocarbon ages, corroborate the geomorphic and soil evidence. The 36Cl results are consistent with available 14C ages and together indicate that the most recent highstands of all three lakes occurred ca. 20-15 ka, late in marine isotope stage (MIS) 2, as shown by previous ages. The 36Cl ages indicate that older lakes in all three basins reached highstands between 100 and 50 ka, and most likely during MIS 4. Shorelines of this age are at about the same or higher altitudes as the younger, MIS 2 shorelines in those basins. The 36Cl results combined with uranium-series ages and one tephra correlation obtained on shorelines higher in altitude than those of MIS 4 and 2 lakes suggest that there were also major lake highstands in the western Great Basin at ca. 100-200 ka, likely corresponding with MIS 6, and during at least two older periods. From these results, we conclude that the preserved shorelines show an apparent decrease in maximum levels with time, suggesting long-term drying of the region since the early middle Pleistocene. ?? 2011 Geological Society of

  15. Early deglaciation of the western sector of the Cordilleran Ice Sheet from cosmogenic nuclide exposure dating, central British Columbia coast

    NASA Astrophysics Data System (ADS)

    Darvill, C.; Menounos, B.; Goehring, B. M.; Lian, O. B.

    2016-12-01

    Reconstructing the retreat of the Cordilleran Ice Sheet (CIS) during the last deglaciation has implications for sea level variability and the peopling of the Americas, but requires robust glacial chronologies. The southern margin of the CIS advanced to its maximum extent at ca. 16 ka, but no directly dated terrestrial limits presently exist on the central coast to constrain the western ice margin prior to ca. 14 ka. Moreover, published marine sediment cores show intervals of ice-rafted debris interpreted to reflect an unstable, marine-terminating western margin that may have rapidly retreated during deglaciation. Here, we present data from two moraines on Calvert Island, British Columbia (51.6°N, 128.1°W) that demarcate the central-western edge of the CIS during deglaciation. The orientation of the moraines suggests that ice flowed southward along the Hugh Sound-Dean Channel fjord system, a major western outlet of the former ice sheet. Terrestrial cosmogenic 10Be nuclide dating of erratic boulders and bedrock associated with a prominent end moraine in the centre of the island yielded a mean weighted exposure age of 16.5 ± 0.3 ka (n=5). Erratic boulders from a second moraine approximately 8 km to the north and 600 m lower in elevation than the first yielded a weighted mean exposure age of 14.2 ± 0.5 ka (n=4). This latter age supports recently reported bracketing radiocarbon ages for stratigraphically equivalent till in a section exposed in the northwest part of the island. We are currently processing twenty-three further 10Be exposure ages from targeted erratics and bedrock to further constrain the timing and extent of deglaciation within this region. Our current data indicate that if the western CIS reached the outer continental shelf it did so prior to ca. 16.5 ka, and was in retreat by the time the southern margin reached its maximum extent. In addition, these new ages indicate that ice free areas existed along the western coast from at least 16.5 ka

  16. 10Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

    NASA Astrophysics Data System (ADS)

    Lupker, Maarten; Lavé, Jérôme; France-Lanord, Christian; Christl, Marcus; Bourlès, Didier; Carcaillet, Julien; Maden, Colin; Wieler, Rainer; Rahman, Mustafizur; Bezbaruah, Devojit; Xiaohan, Liu

    2017-08-01

    The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range and flows from the Tibetan Plateau through the eastern Himalayan syntaxis downstream to the Indo-Gangetic floodplain and the Bay of Bengal. As such, it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. The measured 10Be denudation rates span around 2 orders of magnitude across individual catchments (ranging from 0.03 to > 4 mm yr-1) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates, however, occurs ˜ 150 km downstream of the Namche Barwa-Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse-grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high-concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage, and quartz content of the upstream Tibetan Plateau part of the catchment, which tends to lead to an overestimation of downstream denudation rates. While no direct 10Be denudation measurements were made in the syntaxis, the dilution of the upstream 10Be signal, measured in Tsangpo-Brahmaputra sediments, provides constraints on the

  17. Long-term rates of chemical weathering and physical erosion from cosmogenic nuclides and geochemical mass balance

    NASA Astrophysics Data System (ADS)

    Riebe, Clifford S.; Kirchner, James W.; Finkel, Robert C.

    2003-11-01

    Quantifying long-term rates of chemical weathering and physical erosion is important for understanding the long-term evolution of soils, landscapes, and Earth's climate. Here we describe how long-term chemical weathering rates can be measured for actively eroding landscapes using cosmogenic nuclides together with a geochemical mass balance of weathered soil and parent rock. We tested this approach in the Rio Icacos watershed, Puerto Rico, where independent studies have estimated weathering rates over both short and long timescales. Results from the cosmogenic/mass balance method are consistent with three independent sets of weathering rate estimates, thus confirming that this approach yields realistic measurements of long-term weathering rates. This approach can separately quantify weathering rates from saprolite and from overlying soil as components of the total. At Rio Icacos, nearly 50% of Si weathering occurs as rock is converted to saprolite; in contrast, nearly 100% of Al weathering occurs in the soil. Physical erosion rates are measured as part of our mass balance approach, making it particularly useful for studying interrelationships between chemical weathering and physical erosion. Our data show that chemical weathering rates are tightly coupled with physical erosion rates, such that the relationship between climate and chemical weathering rates may be obscured by site-to-site differences in the rate that minerals are supplied to soil by physical erosion of rock. One can normalize for variations in physical erosion rates using the ;chemical depletion fraction,; which measures the fraction of total denudation that is accounted for by chemical weathering. This measure of chemical weathering intensity increases with increasing average temperature and precipitation in data from climatically diverse granitic sites, including tropical Rio Icacos and six temperate sites in the Sierra Nevada, California. Hence, across a wide range of climate regimes, analysis of

  18. Measurement of natural radioactive nuclide concentrations in various metal ores used as industrial raw materials in Japan and estimation of dose received by workers handling them.

    PubMed

    Iwaoka, Kazuki; Tagami, Keiko; Yonehara, Hidenori

    2009-11-01

    Natural resources such as ores and rocks contain natural radioactive nuclides at various concentrations. If these resources contain high concentrations of natural radioactive nuclides, workers handling them might be exposed to significant levels of radiation. Therefore, it is important to investigate the radioactive activity in these resources. In this study, concentrations of radioactive nuclides in Th, Zr, Ti, Mo, Mn, Al, W, Zn, V, and Cr ores used as industrial raw materials in Japan were investigated. The concentrations of (238)U and (232)Th were determined by inductively coupled plasma mass spectrometry (ICP-MS), while those of (226)Ra, (228)Ra, and (40)K were determined by gamma-ray spectrum. We found the concentrations of (238)U series, (232)Th series, and (40)K in Ti, Mo, Mn, Al, W, Zn, V, and Cr ores to be lower than the critical values defined by regulatory requirements as described in the International Atomic Energy Agency (IAEA) Safety Guide. The doses received by workers handling these materials were estimated by using methods for dose assessment given in a report by the European Commission. In transport, indoor storage, and outdoor storage scenarios, an effective dose due to the use of Th ore was above 4.3 x 10(-2)Sv y(-1), which was higher than that of the other ores. The maximum value of effective doses for other ores was estimated to be about 4.5 x 10(-4)Sv y(-1), which was lower than intervention exemption levels (1.0 x 10(-3)Sv y(-1)) given in International Commission of Radiological Protection (ICRP) Publication 82.

  19. Radioactive nuclides in the incinerator ashes of municipal solid wastes before and after the accident at the Fukushima nuclear power plant.

    PubMed

    Iwahana, Yuki; Ohbuchi, Atsushi; Koike, Yuya; Kitano, Masaru; Nakamura, Toshihiro

    2013-01-01

    Radioactive nuclides in the incinerator ashes of municipal solid wastes were determined by γ-ray spectrometry before and after the accident at the Fukushima nuclear power plant (March 11, 2011). Incinerator ash samples were collected in northern Kyushu, Japan, which is located approximately 1200 km west-southwest (WSW) of the Fukushima nuclear power plant, from April 2006 to March 2007 and from March 2011 to October 2011. (40)K, (137)Cs, (208)Tl, (212)Pb, (214)Pb, (212)Bi, (214)Bi, and (228)Ac were identified in the ashes before the accident (~February 2011) and (134)Cs was identified along with these eight nuclides in the ashes after the accident (March 2011~). A sequential extraction procedure based on a modified Tessier method with added water extraction was used for 1st fly ash sampled in August 2011 because the highest activity concentrations of (134)Cs and (137)Cs were observed for this sample. The speciation of radioactive nuclides in the fly ash was achieved by γ-ray spectrometry and powder X-ray diffractometry for the extraction residues. Little variation was observed in the distribution of the chemical forms of (134)Cs and (137)Cs in 1st fly ash of municipal solid waste; one half of (134)Cs existed as water soluble salts and the other half as carbonate compounds, whereas 75% of (137)Cs existed as water soluble salts with the remainder as carbonates(10%) and sulfides (15%). These results show that 88% of the total radioactive Cs existed in water soluble and ion extractive forms and might be at risk for elution and diffusion with rain and wind.

  20. First results using a new technology for measuring masses of very short-lived nuclides with very high accuracy: The MISTRAL program at ISOLDE

    SciTech Connect

    Monsanglant, C.; Audi, G.; Conreur, G.; Cousin, R.; Doubre, H.; Jacotin, M.; Henry, S.; Kepinski, J.-F.; Lunney, D.; Saint Simon, M. de; Thibault, C.; Toader, C.; Bollen, G.; Lebee, G.; Scheidenberger, C.; Borcea, C.; Duma, M.; Kluge, H.-J.; Le Scornet, G.

    1999-11-16

    MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na, Mg, Al, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

  1. Metaheuristics-Assisted Combinatorial Screening of Eu(2+)-Doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N Compositional Space in Search of a Narrow-Band Green Emitting Phosphor and Density Functional Theory Calculations.

    PubMed

    Lee, Jin-Woong; Singh, Satendra Pal; Kim, Minseuk; Hong, Sung Un; Park, Woon Bae; Sohn, Kee-Sun

    2017-08-21

    A metaheuristics-based design would be of great help in relieving the enormous experimental burdens faced during the combinatorial screening of a huge, multidimensional search space, while providing the same effect as total enumeration. In order to tackle the high-throughput powder processing complications and to secure practical phosphors, metaheuristics, an elitism-reinforced nondominated sorting genetic algorithm (NSGA-II), was employed in this study. The NSGA-II iteration targeted two objective functions. The first was to search for a higher emission efficacy. The second was to search for narrow-band green color emissions. The NSGA-II iteration finally converged on BaLi2Al2Si2N6:Eu(2+) phosphors in the Eu(2+)-doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N compositional search space. The BaLi2Al2Si2N6:Eu(2+) phosphor, which was synthesized with no human intervention via the assistance of NSGA-II, was a clear single phase and gave an acceptable luminescence. The BaLi2Al2Si2N6:Eu(2+) phosphor as well as all other phosphors that appeared during the NSGA-II iterations were examined in detail by employing powder X-ray diffraction-based Rietveld refinement, X-ray absorption near edge structure, density functional theory calculation, and time-resolved photoluminescence. The thermodynamic stability and the band structure plausibility were confirmed, and more importantly a novel approach to the energy transfer analysis was also introduced for BaLi2Al2Si2N6:Eu(2+) phosphors.

  2. Microscopic Shell Model Calculations for the Fluorine Isotopes

    NASA Astrophysics Data System (ADS)

    Barrett, Bruce R.; Dikmen, Erdal; Maris, Pieter; Vary, James P.; Shirokov, Andrey M.

    2015-10-01

    Using a formalism based on the No Core Shell Model (NCSM), we have determined miscroscopically the core and single-particle energies and the effective two-body interactions that are the input to standard shell model (SSM) calculations. The basic idea is to perform a succession of a Okubo-Lee-Suzuki (OLS) transformation, a NCSM calculation, and a second OLS transformation to a further reduced space, such as the sd-shell, which allows the separation of the many-body matrix elements into an ``inert'' core part plus a few valence-nucleons calculation. In the present investigation we use this technique to calculate the properties of the nuclides in the Fluorine isotopic chain, using the JISP16 nucleon-nucleon interaction. The obtained SSM input, along with the results of the SSM calculations for the Fluorine isotopes, will be presented. This work supported in part by TUBITAK-BIDEB, the US DOE, the US NSF, NERSC, and the Russian Ministry of Education and Science.

  3. HENRY'S LAW CALCULATOR

    EPA Science Inventory

    On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations,...

  4. HENRY'S LAW CALCULATOR

    EPA Science Inventory

    On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations,...

  5. Cosmogenic Nuclides 10Be-21Ne Burial Dating of Middle Miocene Sedimentary Formation of the Hongliu Valley in Southern Ningxia Basin: A Case of Isotopic Geochronology Study for the Cenozoic Sedimentary Strata

    NASA Astrophysics Data System (ADS)

    Ma, Yan; Zhang, Huiping; Wang, Weitao; Pang, Jianzhang; Zheng, Dewen

    2016-04-01

    Chronology studies for the Cenozoic sedimentary strata based on the magnetostratigraphy cannot afford the unique chronological sequences in the absence of absolute ages from biostratigraphy or volcanic ash chronology. In situ-produced cosmogenic nuclides provide a powerful tool for the sediment dating based on the time-dependent concentration ratio of two nuclides, which are produced in the same mineral but with different half-lives. Thereinto,10Be-26Al is the most widely used nuclide pairs, of which the available dating range spans the Plio-Pleistocene. But the coupling of 10Be with the stable nuclide 21Ne would significantly improve the burial dating range up to the middle Miocene, which is promising in revolutionizing the chronology study for the Late Cenozoic terrestrial sedimentary sequences. We have applied 10Be-21Ne pair for dating the middle Miocene sediments of the Hongliu Valley in southern Ningxia basin. Two major features of the sediments are involved in our study: (1) sediments originated from the steady erosion of the source area, and (2) the burial depth of our sample after deposition is time dependent due to the gradual accumulation of sediments into basin. The post-burial nuclide production is estimated to be less than 3%, including the contribution by muon interactions, of the total nuclide concentrations measured in our sample. Our 10Be-21Ne analysis demonstrates the age of the burial sample is 12.4(+0.6/-0.4) Ma, and the erosion rate at the source area is 0.26±0.01 cm ka-1. The sample's burial age is consistent with the age constraint set by the Hongliugou Formation (16.7-5.4 Ma) which we collected the sample in. Vertebrate fossils of Platybelodon tongxinensis with an age between 12 and 15 Ma exhumated along with our sample further verifies the reliability of our dating results for the middle Miocene sediments.This study has shown the improved age range of cosmogenic-nuclide burial dating method by incorporating the stable nuclide 21Ne, and has

  6. On the role of fusion neutron source with thorium blanket in forming the nuclide composition of the nuclear fuel cycle of the Russian Federation

    NASA Astrophysics Data System (ADS)

    Shmelev, A. N.; Kulikov, G. G.

    2016-12-01

    The possible role of available thorium resources of the Russian Federation in utilization of thorium in the closed (U-Pu)-fuel cycle of nuclear power is considered. The efficiency of application of fusion neutron sources with thorium blanket for economical use of available thorium resources is demonstrated. The objective of this study is the search for a solution of such major tasks of nuclear power as reduction of the amount of front-end operations in the nuclear fuel cycle and enhancement of its protection against uncontrolled proliferation of fissile materials with the smallest possible alterations in the fuel cycle. The earlier results are analyzed, new information on the amount of thorium resources of the Russian Federation is used, and additional estimates are made. The following basic results obtained on the basis of the assumption of involving fusion reactors with Th-blanket in future nuclear power for generation of the light uranium fraction 232+233+234U and 231Pa are formulated. (1) The fuel cycle would shift from fissile 235U to 233U, which is more attractive for thermal power reactors. (2) The light uranium fraction is the most "protected" in the uranium fuel component, and being mixed with regenerated uranium, it would become reduced-enrichment uranium fuel, which would relieve the problem of nonproliferation of the fissile material. (3) The addition of 231Pa into the fuel would stabilize its neutron-multiplying properties, thus making it possible to implement a long fuel residence time and, as a consequence, increase the export potential of the whole nuclear power technology. (4) The available thorium resource in the vicinity of Krasnoufimsk is sufficient for operation of the large-scale nuclear power industry of the Russian Federation with an electric power of 70 GW for more than one quarter of a century. The general conclusion is that involvement of a small number of fusion reactors with Th-blanket in the future nuclear power industry of the Russian Federation would to a large extent solve its problems and increase its export potential.

  7. On the role of fusion neutron source with thorium blanket in forming the nuclide composition of the nuclear fuel cycle of the Russian Federation

    SciTech Connect

    Shmelev, A. N.; Kulikov, G. G.

    2016-12-15

    The possible role of available thorium resources of the Russian Federation in utilization of thorium in the closed (U–Pu)-fuel cycle of nuclear power is considered. The efficiency of application of fusion neutron sources with thorium blanket for economical use of available thorium resources is demonstrated. The objective of this study is the search for a solution of such major tasks of nuclear power as reduction of the amount of front-end operations in the nuclear fuel cycle and enhancement of its protection against uncontrolled proliferation of fissile materials with the smallest possible alterations in the fuel cycle. The earlier results are analyzed, new information on the amount of thorium resources of the Russian Federation is used, and additional estimates are made. The following basic results obtained on the basis of the assumption of involving fusion reactors with Th-blanket in future nuclear power for generation of the light uranium fraction {sup 232+233+234}U and {sup 231}Pa are formulated. (1) The fuel cycle would shift from fissile {sup 235}U to {sup 233}U, which is more attractive for thermal power reactors. (2) The light uranium fraction is the most “protected” in the uranium fuel component, and being mixed with regenerated uranium, it would become reduced-enrichment uranium fuel, which would relieve the problem of nonproliferation of the fissile material. (3) The addition of {sup 231}Pa into the fuel would stabilize its neutron-multiplying properties, thus making it possible to implement a long fuel residence time and, as a consequence, increase the export potential of the whole nuclear power technology. (4) The available thorium resource in the vicinity of Krasnoufimsk is sufficient for operation of the large-scale nuclear power industry of the Russian Federation with an electric power of 70 GW for more than one quarter of a century. The general conclusion is that involvement of a small number of fusion reactors with Th-blanket in the future nuclear power industry of the Russian Federation would to a large extent solve its problems and increase its export potential.

  8. An automated Monte-Carlo based method for the calculation of cascade summing factors

    NASA Astrophysics Data System (ADS)

    Jackson, M. J.; Britton, R.; Davies, A. V.; McLarty, J. L.; Goodwin, M.

    2016-10-01

    A versatile method has been developed to calculate cascade summing factors for use in quantitative gamma-spectrometry analysis procedures. The proposed method is based solely on Evaluated Nuclear Structure Data File (ENSDF) nuclear data, an X-ray energy library, and accurate efficiency characterisations for single detector counting geometries. The algorithm, which accounts for γ-γ, γ-X, γ-511 and γ-e- coincidences, can be applied to any design of gamma spectrometer and can be expanded to incorporate any number of nuclides. Efficiency characterisations can be derived from measured or mathematically modelled functions, and can accommodate both point and volumetric source types. The calculated results are shown to be consistent with an industry standard gamma-spectrometry software package. Additional benefits including calculation of cascade summing factors for all gamma and X-ray emissions, not just the major emission lines, are also highlighted.

  9. Stability Test for Transient-Temperature Calculations

    NASA Technical Reports Server (NTRS)

    Campbell, W.

    1984-01-01

    Graphical test helps assure numerical stability of calculations of transient temperature or diffusion in composite medium. Rectangular grid forms basis of two-dimensional finite-difference model for heat conduction or other diffusion like phenomena. Model enables calculation of transient heat transfer among up to four different materials that meet at grid point.

  10. Stability Test for Transient-Temperature Calculations

    NASA Technical Reports Server (NTRS)

    Campbell, W.

    1984-01-01

    Graphical test helps assure numerical stability of calculations of transient temperature or diffusion in composite medium. Rectangular grid forms basis of two-dimensional finite-difference model for heat conduction or other diffusion like phenomena. Model enables calculation of transient heat transfer among up to four different materials that meet at grid point.

  11. Distillation Calculations with a Programmable Calculator.

    ERIC Educational Resources Information Center

    Walker, Charles A.; Halpern, Bret L.

    1983-01-01

    Describes a three-step approach for teaching multicomponent distillation to undergraduates, emphasizing patterns of distribution as an aid to understanding the separation processes. Indicates that the second step can be carried out by programmable calculators. (A more complete set of programs for additional calculations is available from the…

  12. Distillation Calculations with a Programmable Calculator.

    ERIC Educational Resources Information Center

    Walker, Charles A.; Halpern, Bret L.

    1983-01-01

    Describes a three-step approach for teaching multicomponent distillation to undergraduates, emphasizing patterns of distribution as an aid to understanding the separation processes. Indicates that the second step can be carried out by programmable calculators. (A more complete set of programs for additional calculations is available from the…

  13. Critical Analysis of Cluster Models and Exchange-Correlation Functionals for Calculating Magnetic Shielding in Molecular Solids.

    PubMed

    Holmes, Sean T; Iuliucci, Robbie J; Mueller, Karl T; Dybowski, Cecil

    2015-11-10

    Calculations of the principal components of magnetic-shielding tensors in crystalline solids require the inclusion of the effects of lattice structure on the local electronic environment to obtain significant agreement with experimental NMR measurements. We assess periodic (GIPAW) and GIAO/symmetry-adapted cluster (SAC) models for computing magnetic-shielding tensors by calculations on a test set containing 72 insulating molecular solids, with a total of 393 principal components of chemical-shift tensors from 13C, 15N, 19F, and 31P sites. When clusters are carefully designed to represent the local solid-state environment and when periodic calculations include sufficient variability, both methods predict magnetic-shielding tensors that agree well with experimental chemical-shift values, demonstrating the correspondence of the two computational techniques. At the basis-set limit, we find that the small differences in the computed values have no statistical significance for three of the four nuclides considered. Subsequently, we explore the effects of additional DFT methods available only with the GIAO/cluster approach, particularly the use of hybrid-GGA functionals, meta-GGA functionals, and hybrid meta-GGA functionals that demonstrate improved agreement in calculations on symmetry-adapted clusters. We demonstrate that meta-GGA functionals improve computed NMR parameters over those obtained by GGA functionals in all cases, and that hybrid functionals improve computed results over the respective pure DFT functional for all nuclides except 15N.

  14. First Results Using a New Technology for Measuring Masses of Very Short-Lived Nuclides with Very High Accuracy: the MISTRAL Program at ISOLDE

    SciTech Connect

    C. Monsanglant; C. Toader; G. Audi; G. Bollen; C. Borcea; G. Conreur; R. Cousin; H. Doubre; M. Duma; M. Jacotin; S. Henry; J.-F. Kepinski; H.-J. Kluge; G. Lebee; G. Le Scornet; D. Lunney; M. de Saint Simon; C. Scheidenberger; C. Thibault

    1999-12-31

    MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na{clubsuit}, Mg, Al{clubsuit}, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

  15. Study of CdMoO4 crystal for a neutrinoless double beta decay experiment with 116Cd and 100Mo nuclides

    NASA Astrophysics Data System (ADS)

    Xue, Ming-Xuan; Zhang, Yun-Long; Peng, Hai-Ping; Xu, Zi-Zong; Wang, Xiao-Lian

    2017-04-01

    The scintillation properties of a CdMoO4 crystal have been investigated experimentally. The fluorescence yields and decay times measured from 22 K to 300 K demonstrate that CdMoO4 crystal is a good candidate for an absorber for a bolometer readout, for both heat and scintillation signals. The results from Monte Carlo studies, taking the backgrounds from 2ν2β of and internal trace nuclides 214Bi and 208Tl into account, show that the expected sensitivity of a CdMoO4 bolometer for neutrinoless double beta decay experiments with an exposure of 100 kg·years is one order of magnitude higher than those of the current sets of the of and Supported by National Natural Science Foundation of China (11275199)

  16. The deep accumulation of 10Be at Utsira, southwestern Norway: Implications for cosmogenic nuclide exposure dating in peripheral ice sheet landscapes

    NASA Astrophysics Data System (ADS)

    Briner, Jason P.; Goehring, Brent M.; Mangerud, Jan; Svendsen, John Inge

    2016-09-01

    Cosmogenic nuclide exposure dating is a widely used method for constraining past ice sheet histories. We scrutinize a recently published data set of cosmogenic 10Be data from erratic boulders in Norway used to constrain the deglaciation of the western Scandinavian Ice Sheet to 20 ka. Our model of the 10Be inventory in glacial surfaces leads us to conclude that the chronology may be afflicted by the deep subsurface accumulation of 10Be during long-lasting ice-free periods that resulted in 10Be ages >10% too old. We suggest that the majority of the dated erratic boulders contain a uniform level of inherited muon-produced 10Be and were derived from bedrock depths >2.5 m and most likely ~4 m. The implication of our finding is that for landscapes that experience long ice-free periods between brief maximum glacial phases, glacial erosion of >5 m is required to remove detectable traces of inherited 10Be.

  17. SOURCES 4C : a code for calculating ([alpha],n), spontaneous fission, and delayed neutron sources and spectra.

    SciTech Connect

    Wilson, W. B.; Perry, R. T.; Shores, E. F.; Charlton, W. S.; Parish, Theodore A.; Estes, G. P.; Brown, T. H.; Arthur, Edward D. ,; Bozoian, Michael; England, T. R.; Madland, D. G.; Stewart, J. E.

    2002-01-01

    SOURCES 4C is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to radionuclide decay. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., an intimate mixture of a-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 44 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 107 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code provides the magnitude and spectra, if desired, of the resultant neutron source in addition to an analysis of the'contributions by each nuclide in the problem. LASTCALL, a graphical user interface, is included in the code package.

  18. SOURCES 4A: A Code for Calculating (alpha,n), Spontaneous Fission, and Delayed Neutron Sources and Spectra

    SciTech Connect

    Madland, D.G.; Arthur, E.D.; Estes, G.P.; Stewart, J.E.; Bozoian, M.; Perry, R.T.; Parish, T.A.; Brown, T.H.; England, T.R.; Wilson, W.B.; Charlton, W.S.

    1999-09-01

    SOURCES 4A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

  19. Effects of slag composition and process variables on decontamination of metallic wastes by melt refining

    SciTech Connect

    Heshmatpour, B.; Copeland, G. L.

    1981-01-01

    Melt refining has been suggested as an alternative for decontamination and volume reduction of low-level-contaminated metallic wastes. Knowledge of metallurgical and thermochemical aspects of the process is essential for effective treatment of various metals. Variables such as slag type and composition, melting technique, and refractory materials need to be identified for each metal or alloy. Samples of contaminated metals were melted with fluxes by resistance furnace or induction heating. The resulting ingots as well as the slags were analyzed for their nuclide contents, and the corresponding partition ratios were calculated. Compatibility of slags and refractories was also investigated, and proper refractory materials were identified. Resistance furnace melting appeared to be a better melting technique for nonferrous scrap, while induction melting was more suitable for ferrous metals. In general uranium contents of the metals, except for aluminum, could be reduced to as low as 0.01 to 0.1 ppM by melt refining. Aluminum could be decontaminated to about 1 to 2 ppM U when certain fluoride slags were used. The extent of decontamination was not very sensitive to slag type and composition. However, borosilicate and basic oxidizing slags were more effective on ferrous metals and Cu; NaNO/sub 3/-NaCl-NaOH type fluxes were desirable for Zn, Pb, and Sn; and fluoride type slags were effective for decontamination of Al. Recrystallized alumina proved to be the most compatible refractory for melt refining both ferrous and nonferrous metals, while graphite was suitable for nonferrous metal processing. In conclusion, melt refining is an effective technique for volume reduction ad decontamination of contaminated metal scrap when proper slags, melting technique, and refractories are used.

  20. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26 Al, 36 Cl, 3 He, and 21 Ne)

    PubMed Central

    Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-01-01

    Abstract This paper focuses on constraining the erosion rate in the area of the Allchar Sb‐As‐Tl‐Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long‐term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L‐8 CD, L1b/R, L1c/R, and L‐4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo‐depths for the ore body Centralni Deo from 4.3 Ma to the present are 250–290 and 750–790 m, respectively, whereas the upper limit of paleo‐depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo‐depth values allow estimating the relative contributions of 205Pb derived from pp‐neutrino and fast cosmic‐ray muons, respectively, which is an important prerequisite for the LOREX experiment. PMID:27587984

  1. Active faulting, mountain growth, and erosion at the margins of the Tibetan Plateau constrained by in situ-produced cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    Hetzel, Ralf

    2013-01-01

    The India-Asia collision zone is a key area for understanding continental plateau formation and mountain building. Two fundamental questions in this context are how the northeastward motion of India is partitioned between strike-slip and thrust faults and how mountain building is counteracted by erosion. Cosmogenic nuclides allow us to address these questions, because they provide age constraints on tectonically offset landforms and constraints on erosion rates. After considerable debate on whether or not major strike-slip faults move at high rates of up to 20-30 mm/yr and absorb most of the continental deformation, it now appears that the three largest faults (Altyn Tagh, Haiyuan, Kunlun) have millennial slip rates of no more than 8-13 mm/yr, consistent with rates of elastic strain accumulation determined by geodetic methods. Furthermore, a significant portion of the lateral slip on these faults is transferred to thrust faults within the collision zone. Both observations indicate that the eastward tectonic escape of material along these faults is less important than often assumed. With respect to mountain building and erosion, cosmogenic nuclide studies show that thrust faults at the northeastern and eastern margins of Tibet (Qilian Shan, Longmen Shan) have vertical slip rates of ~ 0.3 to ~ 2 mm/yr while catchment-wide erosion rates vary from ~ 0.02 to ~ 1.0 mm/yr, with high-relief areas eroding significantly faster than the plateau interior and growing mountains in the foreland. The deeply incised regions have apparently reached an erosional steady-state, in which rock uplift is balanced by erosion. River terraces at active mountain fronts document repeated changes between sediment deposition and fluvial incision. During the Quaternary, incision and terrace formation occurred predominantly at glacial-interglacial transitions but also during interglacial periods. Hence, flights of terraces at the fault-bounded mountain fronts record the interplay between sustained

  2. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides ((26)Al, (36)Cl, (3)He, and (21)Ne).

    PubMed

    Pavićević, M K; Cvetković, V; Niedermann, S; Pejović, V; Amthauer, G; Boev, B; Bosch, F; Aničin, I; Henning, W F

    2016-02-01

    This paper focuses on constraining the erosion rate in the area of the Allchar Sb-As-Tl-Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long-term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive ((26)Al and (36)Cl) and stable ((3)He and (21)Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying (26)Al, (36)Cl, and (21)Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L-8 CD, L1b/R, L1c/R, and L-4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo-depths for the ore body Centralni Deo from 4.3 Ma to the present are 250-290 and 750-790 m, respectively, whereas the upper limit of paleo-depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo-depth values allow estimating the relative contributions of (205)Pb derived from pp-neutrino and fast cosmic-ray muons, respectively, which is an important prerequisite for the LOREX experiment.

  3. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26Al, 36Cl, 3He, and 21Ne)

    NASA Astrophysics Data System (ADS)

    Pavićević, M. K.; Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-02-01

    This paper focuses on constraining the erosion rate in the area of the Allchar Sb-As-Tl-Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long-term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ˜165 m/Ma. The samples from four locations (L-8 CD, L1b/R, L1c/R, and L-4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo-depths for the ore body Centralni Deo from 4.3 Ma to the present are 250-290 and 750-790 m, respectively, whereas the upper limit of paleo-depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo-depth values allow estimating the relative contributions of 205Pb derived from pp-neutrino and fast cosmic-ray muons, respectively, which is an important prerequisite for the LOREX experiment.

  4. Origin, structure and exposure history of a wave-cut platform more than 1 Ma in age at the coast of northern Spain: A multiple cosmogenic nuclide approach

    NASA Astrophysics Data System (ADS)

    Alvarez-Marrón, J.; Hetzel, R.; Niedermann, S.; Menéndez, R.; Marquínez, J.

    2008-01-01

    Along the Asturian coast of northern Spain an uplifted wave-cut platform extends for ˜ 100 km east-west. The steep cliff which bounds the gently seaward-dipping platform to the north increases in height from 30 m in the west to 100 m in the east and reflects the overall eastward increase in platform elevation. The southern edge of the 2-4 km-wide platform runs along the foothills of the Cantabrian Mountains, as constrained by a high-resolution digital elevation model. The marine platform, which was carved into deformed Paleozoic bedrock with abundant quartzite beds, is largely covered by weathered marine and continental sediments. Quartzite samples from flat bedrock outcrops which are currently not covered by sediment or soil yield cosmogenic nuclide concentrations ( 21Ne, 10Be and 26Al) that demonstrate a long and complex exposure history, including periods of burial with partial or complete shielding from cosmic rays. The combination of multiple cosmogenic nuclides yields a minimum age of 1-2 Ma for the platform. Taking into account (i) the horizontal and vertical extent of the platform, (ii) the high resistance to erosion of the quartzitic bedrock, and (iii) published data on the magnitude of past sea level fluctuations, we suggest that the wave-cut platform formed in the Pliocene. Subvertical faults cutting the platform at high angles to the coastline offset the southern edge of the platform by 20 to 40 m and reactivate the pre-existing anisotropy in the Paleozoic bedrock. Uplift and crustal deformation of the coastal region have occurred after platform formation in the Pliocene and may still be active. The slow deformation of the northern edge of the Iberian plate including the Cantabrian Mountains may result from the ongoing slow convergence at an incipient subduction zone extending along the coast of northern Spain.

  5. Geological Context of Cosmogenic-Nuclide Sampling Sites for the CRONUS-Earth Project on the Shoreline of Paleo-Lake Bonneville, Utah

    NASA Astrophysics Data System (ADS)

    Phillips, F. M.

    2005-12-01

    One of the objectives of the NSF-funded CRONUS-Earth Project is to obtain geologically and geochronologically well-constrained samples in which the production rates of a large number of cosmogenic nuclides can be compared. One area sampled for this purpose, in July 2005, was associated with the shoreline of Lake Bonneville, a very large Pleistocene pluvial lake that occupied the current Great Salt Lake basin. The Bonneville highstand represented the all-time high lake level in the basin. The timing of this event is well constrained by 14C dating. The lake approached the Bonneville highstand by ~18.9 ka. The highstand probably lasted ~1.7 ka and ended at 17.4±0.2 ka by downcutting of the lake sill at Red Rock Pass. We sampled two localities associated with the shoreline: Tabernacle Hill and Promontory Point. The Tabernacle Hill basalt flow was erupted during the Bonneville highstand and was partially covered by the lake. We sampled the flow at seven locations approximately 500 m south of the northeast margin of the flow. The location of the Bonneville shoreline, marked by wave erosion and tufa deposition, was verified to be to the northeast of, and below, the sampling sites. Samples were collected from the tops of push-up ridges using a rock saw. Promontory Point was sampled from a pronounced wave-cut bench on the west side. At the sample site, the depth of wave erosion was ~140 m. The bench was cut into quartzite. Samples were collected by rock saw and hammer and chisel from wave-planed bedrock outcrops. Based on geological mapping, the sample sites were 18 to 27 m below the lake surface elevation (depending on sample location), with an estimated uncertainty of ±5 m. The geometry of the pre-Bonneville topography can be reconstructed with a fair degree of confidence, enabling correction of the measured nuclide concentrations for pre-Bonneville production by muons.

  6. Effects of Climate on Long-term Rates of Physical Erosion and Chemical Weathering: Evidence from Cosmogenic Nuclides and Geochemical Mass Balance

    NASA Astrophysics Data System (ADS)

    Kirchner, J. W.; Riebe, C. S.; Ferrier, K. L.; Finkel, R. C.

    2004-12-01

    Cosmogenic nuclides such as 10Be and 26Al have recently become important tools for measuring long-term denudation rates. We have recently shown how cosmogenic nuclide measurements of denudation fluxes can be partitioned into their physical and chemical components, using the enrichment of insoluble tracers in regolith relative to its parent rock. We used these methods to measure long-term rates of physical erosion and chemical weathering for 42 sites, encompassing widely varying climates and denudation rates. Across these sites, mean annual temperatures vary from 2 to 25 ° C, average annual precipitation spans a 20-fold range (from 22 to 420 cm/yr), and denudation rates vary by 32-fold (from 23 to 755 t km-2 yr-2). Our measurements show that chemical weathering rates are tightly coupled with physical erosion rates, such that the relationship between climate and chemical weathering rates may be obscured by site-to-site differences in the rate that minerals are supplied to soil by physical erosion of rock. The relative importance of chemical weathering can be quantified using the "Weathering Intensity Factor" (WIF), the ratio of the chemical weathering rate to the physical erosion rate. Over 60 percent of the variance in WIF's can be explained by a simple Arrhenius-like relationship based on mean annual temperature and average annual precipitation. The temperature-dependence of WIF is roughly half of what one would expect from laboratory measurements of activation energies for feldspar weathering and previous inter-comparisons of short-term average weathering rates from the field. Our results imply that the strength of climate change feedbacks between temperature and silicate weathering rates may be weaker than previously thought, at least in actively eroding, unglaciated granitic terrain similar to our study sites.

  7. ICRP Publication 107. Nuclear decay data for dosimetric calculations.

    PubMed

    Eckerman, K; Endo, A

    2008-01-01

    In this report, the Commission provides an electronic database of the physical data needed in calculations of radionuclide-specific protection and operational quantities. This database supersedes the data of Publication 38 (ICRP, 1983), and will be used in future ICRP publications of dose coefficients for the intake of or exposure to radionuclides in the workplace and the environment.The database contains information on the half-lives, decay chains, and yields and energies of radiations emitted in nuclear transformations of 1252 radionuclides of 97 elements. The CD accompanying the publication provides electronic access to complete tables of the emitted radiations, as well as the beta and neutron spectra. The database has been constructed such that user-developed software can extract the data needed for further calculations of a radionuclide of interest. A Windows-based application is provided to display summary information on a user-specified radionuclide, as well as the general characterisation of the nuclides contained in the database. In addition, the application provides a means by which the user can export the emissions of a specified radionuclide for use in subsequent calculations.

  8. Methods of increasing the performance of radionuclide generators used in nuclear medicine: daughter nuclide build-up optimisation, elution-purification-concentration integration, and effective control of radionuclidic purity.

    PubMed

    Le, Van So; Do, Zoe Phuc-Hien; Le, Minh Khoi; Le, Vicki; Le, Natalie Nha-Truc

    2014-06-10

    Methods of increasing the performance of radionuclide generators used in nuclear medicine radiotherapy and SPECT/PET imaging were developed and detailed for 99Mo/99mTc and 68Ge/68Ga radionuclide generators as the cases. Optimisation methods of the daughter nuclide build-up versus stand-by time and/or specific activity using mean progress functions were developed for increasing the performance of radionuclide generators. As a result of this optimisation, the separation of the daughter nuclide from its parent one should be performed at a defined optimal time to avoid the deterioration in specific activity of the daughter nuclide and wasting stand-by time of the generator, while the daughter nuclide yield is maintained to a reasonably high extent. A new characteristic parameter of the formation-decay kinetics of parent/daughter nuclide system was found and effectively used in the practice of the generator production and utilisation. A method of "early elution schedule" was also developed for increasing the daughter nuclide production yield and specific radioactivity, thus saving the cost of the generator and improving the quality of the daughter radionuclide solution. These newly developed optimisation methods in combination with an integrated elution-purification-concentration system of radionuclide generators recently developed is the most suitable way to operate the generator effectively on the basis of economic use and improvement of purposely suitable quality and specific activity of the produced daughter radionuclides. All these features benefit the economic use of the generator, the improved quality of labelling/scan, and the lowered cost of nuclear medicine procedure. Besides, a new method of quality control protocol set-up for post-delivery test of radionuclidic purity has been developed based on the relationship between gamma ray spectrometric detection limit, required limit of impure radionuclide activity and its measurement certainty with respect to

  9. Programmable calculator stress analysis

    SciTech Connect

    Van Gulick, L.A.

    1983-01-01

    Advanced programmable alphanumeric calculators are well suited for closed-form calculation of pressure-vessel stresses. They offer adequate computing power, portability, special programming features, and simple interactive execution procedures. Representative programs that demonstrate calculator capabilities are presented. Problems treated are stress and strength calculations in thick-walled pressure vessels and the computation of stresses near head/pressure-vessel junctures.

  10. Impact of nuclear data on sodium-cooled fast reactor calculations

    NASA Astrophysics Data System (ADS)

    Aures, Alexander; Bostelmann, Friederike; Zwermann, Winfried; Velkov, Kiril

    2016-03-01

    Neutron transport and depletion calculations are performed in combination with various nuclear data libraries in order to assess the impact of nuclear data on safety-relevant parameters of sodium-cooled fast reactors. These calculations are supplemented by systematic uncertainty analyses with respect to nuclear data. Analysed quantities are the multiplication factor and nuclide densities as a function of burn-up and the Doppler and Na-void reactivity coefficients at begin of cycle. While ENDF/B-VII.0 / -VII.1 yield rather consistent results, larger discrepancies are observed between the JEFF libraries. While the newest evaluation, JEFF-3.2, agrees with the ENDF/B-VII libraries, the JEFF-3.1.2 library yields significant larger multiplication factors.

  11. Experimental and calculational analyses of actinide samples irradiated in EBR-II

    SciTech Connect

    Gilai, D.; Williams, M.L.; Cooper, J.H.; Laing, W.R.; Walker, R.L.; Raman, S.; Stelson, P.H.

    1982-10-01

    Higher actinides influence the characteristics of spent and recycled fuel and dominate the long-term hazards of the reactor waste. Reactor irradiation experiments provide useful benchmarks for testing the evaluated nuclear data for these actinides. During 1967 to 1970, several actinide samples were irradiated in the Idaho EBR-II fast reactor. These samples have now been analyzed, employing mass and alpha spectrometry, to determine the heavy element products. A simple spherical model for the EBR-II core and a recent version of the ORIGEN code with ENDF/B-V data were employed to calculate the exposure products. A detailed comparison between the experimental and calculated results has been made. For samples irradiated at locations near the core center, agreement within 10% was obtained for the major isotopes and their first daughters, and within 20% for the nuclides up the chain. A sensitivity analysis showed that the assumed flux should be increased by 10%.

  12. SOURCES-3A: A code for calculating ({alpha}, n), spontaneous fission, and delayed neutron sources and spectra

    SciTech Connect

    Perry, R.T.; Wilson, W.B.; Charlton, W.S.

    1998-04-01

    In many systems, it is imperative to have accurate knowledge of all significant sources of neutrons due to the decay of radionuclides. These sources can include neutrons resulting from the spontaneous fission of actinides, the interaction of actinide decay {alpha}-particles in ({alpha},n) reactions with low- or medium-Z nuclides, and/or delayed neutrons from the fission products of actinides. Numerous systems exist in which these neutron sources could be important. These include, but are not limited to, clean and spent nuclear fuel (UO{sub 2}, ThO{sub 2}, MOX, etc.), enrichment plant operations (UF{sub 6}, PuF{sub 4}, etc.), waste tank studies, waste products in borosilicate glass or glass-ceramic mixtures, and weapons-grade plutonium in storage containers. SOURCES-3A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides in homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material) and in interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material). The code is also capable of calculating the neutron production rates due to ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude

  13. Interlaminar fracture of composites

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.

    1984-01-01

    Fracture mechanics has been found to be a useful tool for understanding composite delamination. Analyses for calculating strain energy release rates associated with delamination growth have been developed. These analyses successfully characterized delamination onset and growth for particular sources of delamination. Low velocity impact has been found to be the most severe source of composite delamination. A variety of test methods for measuring interlaminar fracture toughness are being developed to identify new composite materials with enhanced delamination resistance.

  14. Personal Finance Calculations.

    ERIC Educational Resources Information Center

    Argo, Mark

    1982-01-01

    Contains explanations and examples of mathematical calculations for a secondary level course on personal finance. How to calculate total monetary cost of an item, monthly payments, different types of interest, annual percentage rates, and unit pricing is explained. (RM)

  15. Comparative radiation resistance calculation for graded- and constant-composition n Al/x/Ga/1-x/As-p Al/z/Ga/1-z/As solar cells

    NASA Technical Reports Server (NTRS)

    Hutchby, J. A.

    1978-01-01

    The performance and radiation resistance of a new double-graded-band-gap solar cell are theoretically determined. The performance of this device is similar to that of the single-graded-band-gap cell. The power-conversion efficiencies of both graded-band-gap structures are shown to be less sensitive to minority-carrier lifetime degradation than a similar constant-composition heteroface cell.

  16. Autistic Savant Calendar Calculators.

    ERIC Educational Resources Information Center

    Patti, Paul J.

    This study identified 10 savants with developmental disabilities and an exceptional ability to calculate calendar dates. These "calendar calculators" were asked to demonstrate their abilities, and their strategies were analyzed. The study found that the ability to calculate dates into the past or future varied widely among these…

  17. Flexible Mental Calculation.

    ERIC Educational Resources Information Center

    Threlfall, John

    2002-01-01

    Suggests that strategy choice is a misleading characterization of efficient mental calculation and that teaching mental calculation methods as a whole is not conducive to flexibility. Proposes an alternative in which calculation is thought of as an interaction between noticing and knowledge. Presents an associated teaching approach to promote…

  18. Calculator-Active Materials.

    ERIC Educational Resources Information Center

    Crow, Tracy, Ed.; Harris, Julia, Ed.

    1997-01-01

    This journal contains brief descriptions of calculator-active materials that were found using Resource Finder, the searchable online catalog of curriculum resources from the Eisenhower National Clearinghouse (ENC). It features both the calculators themselves and the activity books that are used with them. Among the calculators included are those…

  19. Calculators, Computers, and Classrooms.

    ERIC Educational Resources Information Center

    Higgins, Jon L.; Kirschner, Vicky

    Suggestions for using four-function calculators, programmable calculators, and microcomputers are considered in this collection of 36 articles. The first section contains articles considering general implications for mathematics curricula implied by the freedom calculators offer students from routine computation, enabling them to focus on results…

  20. Calculated fission-fragment yield systematics in the region 74 <=Z <= 94 and 90 <=N <= 150

    DOE PAGES

    Möller, Peter; Randrup, Jørgen

    2015-04-01

    Background: In the seminal experiment by Schmidt et al. [Nucl. Phys. A 665, 221 (2000)] in which fission-fragment charge distributions were obtained for 70 nuclides, asymmetric distributions were seen above nucleon number A ≈ 226 and symmetric ones below. Because asymmetric fission had often loosely been explained as a preference for the nucleus to always exploit the extra binding of fragments near ¹³²Sn it was assumed that all systems below A ≈ 226 would fission symmetrically because available isotopes do not have a proton-to-neutron Z/N ratio that allows division into fragments near ¹³²Sn. But the finding by Andreyev et al.more » [Phys. Rev. Lett. 105, 252502 (2010)] did not conform to this expectation because the compound system ¹⁸⁰Hg was shown to fission asymmetrically. It was suggested that this was a new type of asymmetric fission, because no strong shell effects occur for any possible fragment division. Purpose: We calculate a reference database for fission-fragment mass yields for a large region of the nuclear chart comprising 987 nuclides. A particular aim is to establish whether ¹⁸⁰Hg is part of a contiguous region of asymmetric fission, and if so, its extent, or if not, in contrast to the actinides, there are scattered smaller groups of nuclei that fission asymmetrically in this area of the nuclear chart. Methods: We use the by now well benchmarked Brownian shape-motion method and perform random walks on the previously calculated five-dimensional potential-energy surfaces. The calculated shell corrections are damped out with energy according to a prescription developed earlier. Results: We have obtained a theoretical reference database of fission-fragment mass yields for 987 nuclides. These results show an extended region of asymmetric fission with approximate extension 74 ≤ Z ≤ 85 and 100 ≤ N ≤ 120. The calculated yields are highly variable. We show 20 representative plots of these variable features and summarize the main

  1. Calculated fission-fragment yield systematics in the region 74 <=Z <= 94 and 90 <=N <= 150

    SciTech Connect

    Möller, Peter; Randrup, Jørgen

    2015-04-01

    Background: In the seminal experiment by Schmidt et al. [Nucl. Phys. A 665, 221 (2000)] in which fission-fragment charge distributions were obtained for 70 nuclides, asymmetric distributions were seen above nucleon number A ≈ 226 and symmetric ones below. Because asymmetric fission had often loosely been explained as a preference for the nucleus to always exploit the extra binding of fragments near ¹³²Sn it was assumed that all systems below A ≈ 226 would fission symmetrically because available isotopes do not have a proton-to-neutron Z/N ratio that allows division into fragments near ¹³²Sn. But the finding by Andreyev et al. [Phys. Rev. Lett. 105, 252502 (2010)] did not conform to this expectation because the compound system ¹⁸⁰Hg was shown to fission asymmetrically. It was suggested that this was a new type of asymmetric fission, because no strong shell effects occur for any possible fragment division. Purpose: We calculate a reference database for fission-fragment mass yields for a large region of the nuclear chart comprising 987 nuclides. A particular aim is to establish whether ¹⁸⁰Hg is part of a contiguous region of asymmetric fission, and if so, its extent, or if not, in contrast to the actinides, there are scattered smaller groups of nuclei that fission asymmetrically in this area of the nuclear chart. Methods: We use the by now well benchmarked Brownian shape-motion method and perform random walks on the previously calculated five-dimensional potential-energy surfaces. The calculated shell corrections are damped out with energy according to a prescription developed earlier. Results: We have obtained a theoretical reference database of fission-fragment mass yields for 987 nuclides. These results show an extended region of asymmetric fission with approximate extension 74 ≤ Z ≤ 85 and 100 ≤ N ≤ 120. The calculated yields are highly variable. We show 20 representative plots of these variable features and summarize the

  2. Consideration of geomorphological uncertainties with terrestrial cosmogenic nuclide dating (TCND): combining Schmidt-hammer and 10Be dating, Southern Alps, New Zealand

    NASA Astrophysics Data System (ADS)

    Winkler, Stefan

    2010-05-01

    As the importance of glaciers as key indicators of global change has increased during recent years, investigating Holocene glaciers chronologies has gained higher attention accordingly. One reason is the need for a better understanding of the climate - glacier relationship. Comparative studies play a major role in this field of research owing to the natural diversity of glacier behaviour. Detailed Holocene glacier chronologies are, furthermore, necessary to verify and eventually adjust glacier models indispensable for many attempts to predict future glacier changes. The Southern Alps of New Zealand are one of the few key study areas on the Southern Hemisphere where, in general, evidence is still sparse compared to its Northern counterpart. Improvement and reassessment of the Late Holocene glacier chronology in this region is, therefore, an important goal of current research. Recently, terrestrial (in situ) cosmogenic nuclide (10Be) surface exposure dating has been increasingly applied to Holocene moraines in New Zealand and elsewhere. In the context of numerical ("absolute") dating techniques, terrestrial cosmogenic nuclide dating (TCND) seems to have been established as an alternative to the previously dominating radiocarbon (14C) dating of organic material (plant remains, organic-rich soil layers etc.) buried beneath or within moraines. Precision and time resolution achieved by the newest laboratory standards and procedures (Schaefer et al. 2009) is truly a milestone and will promote future attempts of TCND in any comparable context. Maybe, TCND has the potential to at least partially replace radiocarbon (14C) dating in its dominating role for the "absolute" dating of Holocene glacial deposits. By contrast, field sampling for TCND often lacks appropriate consideration of geomorphological uncertainties. Whereas much effort is made with the high precision results achieved in the laboratory, the choice of boulders sampled on Holocene moraines is often purely made

  3. How Do Calculators Calculate Trigonometric Functions?

    ERIC Educational Resources Information Center

    Underwood, Jeremy M.; Edwards, Bruce H.

    How does your calculator quickly produce values of trigonometric functions? You might be surprised to learn that it does not use series or polynomial approximations, but rather the so-called CORDIC method. This paper will focus on the geometry of the CORDIC method, as originally developed by Volder in 1959. This algorithm is a wonderful…

  4. Utilization of short- and medium-lived nuclides for the trace-element characterization of food samples

    SciTech Connect

    Chatt, A.; McDowell, L.S.; Pegg, D.L.

    1986-01-01

    Food has long been known to play a key role not only in the health status of human beings but also in their social lives. Relationships between food and physical as well as spiritual well-beings have been cited in ancient Chinese, Greek, and Indian literatures. Modern medicine, curative as well as preventive, values the nutritional aspects of food. In this regard, there exists an increasing interest in estimating the average daily intake of biologically important elements through food. Instrumental neutron activation analysis (INAA) is particularly well suited for the simultaneous determinations of major, minor, and trace elements in both individual food items and composite diets. In the present study, emphasis is placed on the development of reliable and rapid INAA methods for measuring concentrations of ten elements of nutritional interest in food samples.

  5. General eigenstates of Maxwell's equations in a two-constituent composite medium and their application to a calculation of the local electric field in a flat-slab microstructure

    NASA Astrophysics Data System (ADS)

    Farhi, Asaf; Bergman, David J.

    2016-09-01

    An exact calculation of the local electric field E(r) is described for the case of an external current or plane wave source in a setup of an E1, μ1 slab in an E2, μ2 medium. For this purpose we first calculate all the general eigenstates of the full Maxwell equations. These eigenstates are then used to develop an exact expansion for the physical values of E(r) in the system characterized by physical values of E1, E2, μ1, and μ2. Results are compared with those of a previous calculation of the local field where μ = 1 everywhere. Numerical results are shown for the eigenvalues in practically important configurations where attaining an optical image with sub-wavelength resolution has practical significance. We show that the k >> k2 components are enhanced for the TM field when E1/E2 = -1 and for the TE field when μ1/μ2 = -1 where the enhancement of the evanescent waves starts from lower k values as we approach a setup with both E1/E2 = -1 and μ1/μ2 = -1. We also show that the eigenfunctions for the setup where μ = 1 everywhere correspond to configurations of 3D phased arrays.

  6. Compositional dependence of the local structure of Se{sub x}Te{sub 1-x} alloys: Electron energy-loss spectra, real-space multiple-scattering calculations, and first-principles molecular dynamics

    SciTech Connect

    Katcho, N. A.; Lomba, E.; Urones-Garrote, E.; Otero-Diaz, L. C.; Landa-Canovas, A. R.

    2006-06-01

    In this work we present an investigation on the composition dependence of the local structure in Se{sub x}Te{sub 1-x} crystalline alloys analyzing their experimental energy-loss spectra with the aid of a real-space multiple-scattering modeling approach and first-principles molecular dynamics. The concourse of this latter technique is essential for a proper modeling of the alloy spectra. From our results, it can be inferred that Se{sub x}Te{sub 1-x} alloys exhibit a high degree of substitutional disorder ruling out the existence of fully ordered alternating copolymer chains of Se and Te atoms.

  7. Post-irradiation analysis of an ISOLDE lead-bismuth target: Stable and long-lived noble gas nuclides

    NASA Astrophysics Data System (ADS)

    Leya, I.; Grimberg, A.; David, J.-C.; Schumann, D.; Neuhausen, J.; Zanini, L.; Noah, E.

    2016-07-01

    We measured the isotopic concentrations of long-lived and stable He, Ne, Ar, Kr, and Xe isotopes in a sample from a lead-bismuth eutectic target irradiated with 1.0 and 1.4 GeV protons. Our data indicate for most noble gases nearly complete release with retention fractions in the range of percent or less. Higher retention fractions result from the decay of long-lived radioactive progenitors from groups 1, 2, or 7 of the periodic table. From the data we can calculate a retention fraction for 3H of 2-3%. For alkaline metals we find retention fractions of about 10%, 30%, and 50% for Na, Rb, and Cs, respectively. For the alkaline earth metal Ba we found complete retention. Finally, the measured Kr and Xe concentrations indicate that there was some release of the halogens Br and I during and/or after the irradiation.

  8. INC Model interpretation of the proton induced residual nuclide production cross sections below 2 GeV

    SciTech Connect

    Divadeenam, M.; Ward, T.E.; Spergel, M.S.; Lakatos, S.; Manche, E.P.

    1991-12-31

    For the purposes of interpreting the abundances of various isotopes in meteorites or on lunar and planetary surfaces exposed to fragmentation by cosmic rays, Webber et al. recently reported the measured total elemental and isotopic cross sections with heavy ions as projectiles on H, He, and C targets with beam energies of 0.33 - 1.7 GeV/nucleon. We employ the INC model to predict the fragmentation of the heavy ions in a hydrogen target with the inverse reaction process: proton bombardment of a heavy-ion nucleus leading to spallation products. Charge-changing and mass-changing cross sections are calculated for proton bombardment of an {sup 56}Fe target with beam energies ranging from 0.33 to 1.88 GeV. Total Z-changing and A-changing cross sections in the energy range 0.6 to 1.88 GeV are in excellent agreement with the corresponding experimental data of Webber et al. and Westfall at al., while the agreement below 0.6 GeV proton energy is not as good. The general trend of the Z-changing cross sections are reproduced by the model calculations at each proton incident energy. The interaction of 200-MeV protons with synthetic Stony Meteorite samples was undertaken to explain radionuclide production in a cosmic-ray environment. The BNL Linac 200-MeV-proton beam was used to irradiate synthetic Stony Meteorites to simulate cosmic-ray exposures corresponding to 6.4 and 16.4 million years. Each irradiated sample was analyzed with the help of a high-resolution gamma-ray spectrometer for long-lived radioisotopes. The intranuclear cascade code HETC was employed to simulate the 200-MeV proton bombardment on the meteorite samples to predict the radionuclides {sup 7}Be, {sup 22}Na, {sup 46}Mn, and {sup 56}Co produced in the experimental investigation.

  9. Time-scales of sedimentary transfer and weathering processes from U-series nuclides: Clues from the Himalayan rivers

    NASA Astrophysics Data System (ADS)

    Granet, M.; Chabaux, F.; Stille, P.; France-Lanord, C.; Pelt, E.

    2007-09-01

    In order to define time-scales of erosion and sedimentary transfer in the Himalaya, 238U- 234U- 230Th disequilibria have been analysed in river bank sediments and in bedloads collected along the Kali Gandaki river, one of the main Nepalese rivers, and in the Ghaghara and Gandak rivers, two major plain tributaries of the Ganges. The Th activity ratios and U/Th ratios in river sediments of the two Ganges tributaries constantly decrease from upstream to downstream. This is related to the maturation of sediments by weathering during their transfer to the plain. The U-series data allow to calculate a transfer time for the sediments in the alluvial Gangetic plain from the chain front to the confluence with the Ganges of about 100 kyr for both rivers. The Kali Gandaki river sediment data highlight a decrease of both the Th isotopic and U/Th ratios which is explained by a mixing between two sources with similar U/Th ratios but having suffered a different U-Th fractionation history. Interpretation of the U-series data in the frame of this scenario gives long time-scales of weathering of several 100's kyr for the Himalayan terranes. The results imply that Himalayan bedrocks are submitted to a long in situ stage of weathering before their erosion and transfer into the rivers. In addition, occurrence of similar U-Sr signatures in dissolved (i.e. < 0.1-0.2 μm) and sediment phases of the Kali Gandaki river suggests that "dissolved" uranium could be carried by colloids constituted by sedimentary microparticles. This precludes the use of U-series disequilibria in this river to calculate weathering budgets and to assess whether the erosion is working at steady-state or not.

  10. INC Model interpretation of the proton induced residual nuclide production cross sections below 2 GeV

    SciTech Connect

    Divadeenam, M.; Ward, T.E. ); Spergel, M.S.; Lakatos, S.; Manche, E.P. )

    1991-01-01

    For the purposes of interpreting the abundances of various isotopes in meteorites or on lunar and planetary surfaces exposed to fragmentation by cosmic rays, Webber et al. recently reported the measured total elemental and isotopic cross sections with heavy ions as projectiles on H, He, and C targets with beam energies of 0.33 - 1.7 GeV/nucleon. We employ the INC model to predict the fragmentation of the heavy ions in a hydrogen target with the inverse reaction process: proton bombardment of a heavy-ion nucleus leading to spallation products. Charge-changing and mass-changing cross sections are calculated for proton bombardment of an {sup 56}Fe target with beam energies ranging from 0.33 to 1.88 GeV. Total Z-changing and A-changing cross sections in the energy range 0.6 to 1.88 GeV are in excellent agreement with the corresponding experimental data of Webber et al. and Westfall at al., while the agreement below 0.6 GeV proton energy is not as good. The general trend of the Z-changing cross sections are reproduced by the model calculations at each proton incident energy. The interaction of 200-MeV protons with synthetic Stony Meteorite samples was undertaken to explain radionuclide production in a cosmic-ray environment. The BNL Linac 200-MeV-proton beam was used to irradiate synthetic Stony Meteorites to simulate cosmic-ray exposures corresponding to 6.4 and 16.4 million years. Each irradiated sample was analyzed with the help of a high-resolution gamma-ray spectrometer for long-lived radioisotopes. The intranuclear cascade code HETC was employed to simulate the 200-MeV proton bombardment on the meteorite samples to predict the radionuclides {sup 7}Be, {sup 22}Na, {sup 46}Mn, and {sup 56}Co produced in the experimental investigation.

  11. Molecular structure and conformational composition of 1,3-dihydroxyacetone studied by combined analysis of gas-phase electron diffraction data, rotational constants, and results of theoretical calculations. Ideal gas thermodynamic properties of 1,3-dihydroxyacetone.

    PubMed

    Dorofeeva, Olga V; Vogt, Natalja; Vogt, Jürgen; Popik, Mikhail V; Rykov, Anatolii N; Vilkov, Lev V

    2007-07-19

    The molecular structure of 1,3-dihydroxyacetone (DHA) has been studied by gas-phase electron diffraction (GED), combined analysis of GED and microwave (MW) data, ab initio, and density functional theory calculations. The equilibrium re structure of DHA was determined by a joint analysis of the GED data and rotational constants taken from the literature. The anharmonic vibrational corrections to the internuclear distances (re-ra) and to the rotational constants (B(i)e-B(i)0) needed for the estimation of the re structure were calculated from the B3LYP/cc-pVTZ cubic force field. It was found that the experimental data are well reproduced by assuming that DHA consists of a mixture of three conformers. The most stable conformer of C2v symmetry has two hydrogen bonds, whereas the next two lowest energy conformers (Cs and C1 symmetry) have one hydrogen bond and their abundance is about 30% in total. A combined analysis of GED and MW data led to the following equilibrium structural parameters (re) of the most abundant conformer of DHA (the uncertainties in parentheses are 3 times the standard deviations): r(C=O)=1.215(2) A, r(C-C)=1.516(2) A, r(C-O)=1.393(2) A, r(C-H)=1.096(4) A, r(O-H)=0.967(4) A, angleC-C=O=119.9(2) degrees, angleC-C-O=111.0(2) degrees, angleC-C-H=108.2(7) degrees, angleC-O-H=106.5(7) degrees. These structural parameters reproduce the experimental B(i)0 values within 0.05 MHz. The experimental structural parameters are in good agreement with those obtained from theoretical calculations. Ideal gas thermodynamic functions (S degrees (T), C degrees p(T), and H degrees (T)-H degrees (0)) of DHA were calculated on the basis of experimental and theoretical molecular parameters obtained in this work. The enthalpy of formation of DHA, -523+/-4 kJ/mol, was calculated by the atomization procedure using the G3X method.

  12. Authigenic 10Be/9Be ratio signatures of the cosmogenic nuclide production linked to geomagnetic dipole moment variation since the Brunhes/Matuyama boundary

    NASA Astrophysics Data System (ADS)

    Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L.; Valet, Jean-Pierre; Bassinot, Franck; Ménabréaz, Lucie; Guillou, Valéry; Choy, Sandrine; Beaufort, Luc

    2016-11-01

    Geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium-10 (10Be) production rates. Authigenic 10Be/9Be ratios (proxy of atmospheric 10Be production) from oceanic cores therefore complete the classical information derived from relative paleointensity (RPI) records. This study presents new authigenic 10Be/9Be ratio results obtained from cores MD05-2920 and MD05-2930 collected in the west equatorial Pacific Ocean. Be ratios from cores MD05-2920, MD05-2930 and MD90-0961 have been stacked and averaged. Variations of the authigenic 10Be/9Be ratio are analyzed and compared with the geomagnetic dipole low series reported from global RPI stacks. The largest 10Be overproduction episodes are related to dipole field collapses (below a threshold of 2 × 1022 Am2) associated with the Brunhes/Matuyama reversal, the Laschamp (41 ka) excursion, and the Iceland Basin event (190 ka). Other significant 10Be production peaks are correlated to geomagnetic excursions reported in literature. The record was then calibrated by using absolute dipole moment values drawn from the Geomagia and Pint paleointensity value databases. The 10Be-derived geomagnetic dipole moment record, independent from sedimentary paleomagnetic data, covers the Brunhes-Matuyama transition and the whole Brunhes Chron. It provides new and complementary data on the amplitude and timing of millennial-scale geomagnetic dipole moment variations and particularly on dipole moment collapses triggering polarity instabilities.

  13. 12. 3-min /sup 256/Cf and 43-min /sup 258/Md and systematics of the spontaneous fission propertiesof heavy nuclides

    SciTech Connect

    Hoffman, D.C.; Wilhelmy, J.B.; Weber, J.; Daniels, W.R.; Hulet, E.K.; Lougheed, R.W.; Landrum, J.H.; Wild, J.F.; Dupzyk, R.J.

    1980-03-01

    The new isotope 12.3-min /sup 256/Cf was produced via the /sup 254/Cf(t,p) reaction, and a new 43-min isomer of /sup 258/Md was produced via the /sup 255/Es(..cap alpha..,n) reaction. The fragment mass and kinetic energy distributions from the spontaneous fission of /sup 256/Cf were found to be very similar to those from the spontaneous fission of lighter Cf isotopes. The mass division is primarily asymmetric, and the average total kinetic energy is 189.8 +- 0.9 MeV. The 43-min /sup 258/Md presumably decays by electron capture and provides an opportunity to study the mass and kinetic energy distributions from the spontaneous fission of the 380-..mu..s /sup 258/Fm daughter. The observed narrow, symmetric mass distribution and the most probable total kinetic energy of 238 +- 3 MeV are similar to those reported for the spontaneous fission of /sup 259/Fm but show a sharp increase in symmetric mass division and total kinetic energy compared to /sup 257/Fm and the lighter Fm isotopes. No such abrupt change in properties was observed for /sup 256/Cf, which, like /sup 258/Fm, has 158 neutrons. The marked difference between the spontaneous fission properties of the heavier Fm isotopes and those of other spontaneously fissioning nuclides is compared to some theoretical predictions.

  14. Long-term rates of chemical weathering and physical erosion in extreme climates, measured by cosmogenic nuclides and geochemical mass balance

    NASA Astrophysics Data System (ADS)

    Riebe, C. S.; Kirchner, J. W.; Finkel, R. C.

    2001-12-01

    Chemical weathering and physical erosion jointly regulate soil development and deliver sediment and solutes to riverine habitats. Chemical weathering also generates nutrients and helps regulate global climate over million year timescales. Thus it is important to quantify long-term rates of weathering and erosion in different environments. New cosmogenic nuclide and geochemical mass balance techniques can be widely applied to measure long-term rates of chemical weathering and physical erosion. In previous work, we used those techniques to show that both physical erosion and chemical weathering rates are insensitive to differences in climate across a set of granitic Sierra Nevada study sites that span 20-145 cm/yr in average precipitation and 4-15 ° C in mean annual temperature. Our measurements also showed that long-term rates of chemical weathering and physical erosion are tightly coupled, possibly because chemical weathering rates are regulated by rates of fresh mineral supply by physical erosion of rock. Here we present long-term rates of chemical weathering and physical erosion from new sites with more extreme climates, including both temperate and tropical rainforests. Overall, mean annual temperature spans 4-22 ° C and average precipitation span 20-420 cm/yr across our sites. Our new weathering and erosion data should reveal whether climatic effects on rates of weathering and erosion are more pronounced over a greatly extended range of climates.

  15. Measuring the Retreat Velocity of the Laurentide Ice Sheet by Cosmogenic Nuclides? Be-10 Dating of Glacial Features in Lower Hudson Valley

    NASA Astrophysics Data System (ADS)

    Steinberg, R.; Kelly, M.; Schaefer, J. M.; Rinterknecht, V.; Schwartz, R.; Balco, G.

    2005-12-01

    The Laurentide Ice Sheet (LIS) was the earth's dominant continental ice sheet during the Last Glacial Maximum (LGM). The LIS deglaciation represents a dramatic environmental change that released enormous amounts of fresh water to the Atlantic Ocean, potentially inhibiting the North Atlantic Deep Water formation, thus affecting the thermohaline ocean circulation and global climate. To evaluate the impact of this fresh-water signal, it is important to determine the timing and rate of the LIS retreat, particularly along the Eastern margin of the United States. Glacial geologic features in the Lower Hudson Valley region provide evidence of the advance of LIS to its LGM terminus at Long Island and the subsequent ice recession. The surface exposure dating method using the cosmogenic nuclide Be-10 is applied to date glacially transported erratic boulders and scoured bedrock in two areas, Black Rock Forest and Harriman State Park, in the Lower Hudson Valley. We compare these Be-10 dates with numerous Be-10 dates from the terminal moraine on Long Island (Harbor Hill Moraine) and its extension in Connecticut (Charlestown Moraine). The goal of this project is to develop a chronology of the recessional ice margin. A comparison of Be-10 dates from the terminal moraine at Long Island with those located in the Lower Hudson Valley region yields a first order measure of the rate of the LIS retreat.

  16. The behavior of the uranium decay chain nuclides and thorium during the flank eruptions of Kilauea (Hawaii) between 1983 and 1985

    SciTech Connect

    Reinitz, I.M.; Turekian, K.K. )

    1991-12-01

    The concentrations of members of the {sup 238}U decay chain and {sup 232}Th have been determined for the lavas that erupted on the East Rift Zone of Kilauea Volcano, Hawaii (Puu Oo) between January 1983 and January 1985. There was a decrease during the first 180 days in the abundances of all nuclides, following the behavior of the incompatible elements. ({sup 230}Th/{sup 238}U) varies with ({sup 232}Th/{sup 238}U) yielding a batch process age for the source magma of 127,800 {plus minus} 28,500 (2{omega}) y, similar to East Pacific Rise basalts. No ({sup 226}Ra/{sup 230}Th) disequilibrium was evident at Puu Oo although Haleakala and Loihi show significant excesses of ({sup 226}Ra) over ({sup 230}Th). The initial ({sup 210}Pb) excess relative to ({sup 226}Ra) implies strong incompatibility of {sup 210}Pb probably with the help of chloride complexing, and the deficiency in later episodes indicates volatilization from the melt mediated by the formation of volatile chloride compounds.

  17. Uranium, radium and thorium in soils with high-resolution gamma spectroscopy, MCNP-generated efficiencies, and VRF non-linear full-spectrum nuclide shape fitting

    NASA Astrophysics Data System (ADS)

    Metzger, Robert; Riper, Kenneth Van; Lasche, George

    2017-09-01

    A new method for analysis of uranium and radium in soils by gamma spectroscopy has been developed using VRF ("Visual RobFit") which, unlike traditional peak-search techniques, fits full-spectrum nuclide shapes with non-linear least-squares minimization of the chi-squared statistic. Gamma efficiency curves were developed for a 500 mL Marinelli beaker geometry as a function of soil density using MCNP. Collected spectra were then analyzed using the MCNP-generated efficiency curves and VRF to deconvolute the 90 keV peak complex of uranium and obtain 238U and 235U activities. 226Ra activity was determined either from the radon daughters if the equilibrium status is known, or directly from the deconvoluted 186 keV line. 228Ra values were determined from the 228Ac daughter activity. The method was validated by analysis of radium, thorium and uranium soil standards and by inter-comparison with other methods for radium in soils. The method allows for a rapid determination of whether a sample has been impacted by a man-made activity by comparison of the uranium and radium concentrations to those that would be expected from a natural equilibrium state.

  18. The Neutrino Energy Loss of Nuclides by K-shell Continuum State Electron Capture at the Late Stage of Stellar Evolution

    NASA Astrophysics Data System (ADS)

    Liu, J. J.; Lin, Y.

    2013-01-01

    Based on the Weinberg-Salam theory and taken into consideration of the Coulomb effect on electron gas, the neutrino energy loss rates by K-shell continuum state electron capture are discussed for ^{12}C, ^{16}O, ^{20}Ne, ^{24}Mg, ^{28}Si and ^{56}Fe under the condition of complete ionization and at the late stage of stellar evolution. Our results are compared with those of Beaudet, Petrosian and Salpeter (BPS). It is shown that at relatively high temperatures (e.g., {T_9 = 0.1} and {T_9 = 1}, T_9 represents the temperature in units of 10^9 K), our results agree well with BPS's. However, at relatively low temperatures (e.g., {T_9 = 0.01} and {T_9 = 0.001}), the neutrino energy loss rates of BPS for ^{16}O, ^{20}Ne, ^{24}Mg and ^{28}Si are higher than our results by 10˜ 70 times, and even by 2 orders of magnitude for nuclide ^{12}C. Our results may be of great importance in the research of late stellar evolution, especially for the cooling mechanism of white dwarf, during which the nucleus collapsed to the stage with a relatively low temperature and intermediate density.

  19. Calculators: managing with technology.

    PubMed

    Goldstone, L

    1980-07-25

    When the calculators do the calculating, the managers can do the managing. Len Goldstone of the UMIST Department of Management Sciences examines how close we are to that ideal. There are, he says, calculators of three levels of complexity and price, but warns that tomorrow's manager may find even the most sophisticated of today's instruments clumsy compared to the mini-computers now being developed.

  20. Influence of halide composition on the structural, electronic, and optical properties of mixed CH3NH3Pb (I1-xBrx) 3 perovskites calculated using the virtual crystal approximation method

    NASA Astrophysics Data System (ADS)

    Jong, Un-Gi; Yu, Chol-Jun; Ri, Jin-Song; Kim, Nam-Hyok; Ri, Guk-Chol

    2016-09-01

    Extensive studies have demonstrated the promising capability of the organic-inorganic hybrid halide perovskite CH3NH3PbI3 in solar cells with a high power conversion efficiency exceeding 20%. However, the intrinsic as well as extrinsic instabilities of this material remain the major challenge to the commercialization of perovskite-based solar cells. Mixing halides is expected to resolve this problem. Here, we investigate the effect of chemical substitution in the position of the halogen atom on the structural, electronic, and optical properties of mixed halide perovskites CH3NH3Pb (I1-xBrx) 3 with a pseudocubic phase using the virtual crystal approximation method within density functional theory. With an increase of Br content x from 0.0 to 1.0, the lattice constant decreases in proportion to x with the function of a (x )=6.420 -0.333 x (Å), while the band gap and the exciton binding energy increase with the quadratic function of Eg(x ) =1.542 +0.374 x +0.185 x2 (eV) and the linear function of Eb(x ) =0.045 +0.057 x (eV), respectively. The photoabsorption coefficients are also calculated, showing a blueshift of the absorption onsets for higher Br contents. We calculate the phase decomposition energy of these materials and analyze the electronic charge density difference to estimate the material stability. Based on the calculated results, we suggest that the best match between efficiency and stability can be achieved at x ≈0.2 in CH3NH3Pb (I1-xBrx) 3 perovskites.