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Sample records for 232th 237np 231pa

  1. Distinguishing fissions of 232Th, 237Np and 238U with beta-delayed gamma rays

    NASA Astrophysics Data System (ADS)

    Iyengar, A.; Norman, E. B.; Howard, C.; Angell, C.; Kaplan, A.; Ressler, J. J.; Chodash, P.; Swanberg, E.; Czeszumska, A.; Wang, B.; Yee, R.; Shugart, H. A.

    2013-06-01

    Measurements of beta-delayed gamma-ray spectra following 14-MeV neutron-induced fissions of 232Th, 238U, and 237Np were conducted at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Spectra were collected for times ranging from 1 min to 14 h after irradiation. Intensity ratios of gamma-ray lines were extracted from the data that allow identification of the fissioning isotope.

  2. Nondestructive Determination of 235U Enrichment of Uranium Samples in the Presence of Actinides (232Th, 236U, 237Np)

    NASA Astrophysics Data System (ADS)

    Stogov, Yu V.

    2017-01-01

    The measurements were performed using a planar Ge detector. The multi-group analysis (MGA) for the determination isotopic abundances in low enriched uranium samples is applied in this study. In order to perform the analysis of complex gamma-spectrums, were taken a number of gamma-spectrums of single reference samples, containing 235U, 238U, 232Th, 236U, 237Np with declared isotopic abundance. The gamma-ray spectrums in the range of low energy X-ray and gamma-ray peaks of these samples were obtained and analyzed.

  3. The applicability of MGA method for depleted and natural uranium isotopic analysis in the presence of actinides (232Th, 237Np, 233Pa and 241Am).

    PubMed

    Yücel, Haluk

    2007-11-01

    The multi-group analysis (MGA) method for the determination of uranium isotopic abundances in depleted uranium (DU) and natural uranium (NU) samples is applied in this study. A set of non-destructive gamma-ray measurements of DU and NU samples were performed using a planar Ge detector. The relative abundances of 235U and 238U isotopes were compared with the declared values of the standards. The relative abundance for 235U obtained by MGA for a "clean" DU or NU sample with a content of uranium>1wt% is determined with an accuracy of about +/-5%. However, when several actinides such as 232Th, 237Np, 233Pa and 241Am are present along with uranium isotopes simulating "dirty" DU or NU, it has been observed that MGA method gives erroneous results. The 235U abundance results for the samples were 6-25 times higher than the declared values in the presence of above-mentioned actinides, since MGA is utilized the X-ray and gamma-ray peaks in the 80-130 keV energy region, covering XKalpha and XKbeta regions. After the least-squares fitting of the spectra, it is found that the increases in the intensities of the X-ray and gamma-ray peaks of uranium are remarkably larger in the complex 80-130 keV region. On the other hand, it is observed that the interferences of the actinide peaks are relatively less dominant in the higher gamma-ray region of 130-300 keV. The results imply the need for dirty DU and NU samples that the MGA method should utilize the higher energy gamma-rays (up to 1001 keV of (234m)Pa) combined with lower energies of the spectra, which may be collected in a two detector mode (a planar Ge and a high efficient coaxial Ge).

  4. Criticality of a {sup 237}Np Sphere

    SciTech Connect

    Sanchez, Rene G.; Hayes, David K.; Cappiello, Charlene C.; Myers, William L.; Jaegers, Peter J.; Clement, Steven D.; Butterfield, Kenneth B.

    2003-07-22

    A critical mass experiment using a 6-kg {sup 237}Np sphere has been performed. The purpose of the experiment is to get a better estimate of the critical mass of {sup 237}Np. To attain criticality, the {sup 237}Np sphere was surrounded with 93 wt % {sup 235}U shells. A 1/M as a function of uranium mass was performed. An MCNP neutron transport code was used to model the experiment. The MCNP code yielded a k{sub eff} of 0.99089 {+-} 0.0003 compared with a k{sub eff} 1.0026 for the experiment. Based on these results, it is estimated that the critical mass of {sup 237}Np ranges from kilogram weights in the high fifties to low sixties.

  5. Nuclear resonance fluorescence of {sup 237}Np

    SciTech Connect

    Angell, C. T.; Yee, R.; Joshi, T. H.; Swanberg, E.; Norman, E. B.; Hicks, C. L. Jr.; Klimenko, A.; Korbly, S.; Wilson, C.; Kulp, W. D.; Warren, G. A.; Bray, T. H.; Copping, R.; Glans, P. A.; Tyliszczak, T.; Shuh, D. K.

    2010-11-15

    Measurements of states excited by nuclear resonance fluorescence in {sup 237}Np were performed using a bremsstrahlung beam. Fifteen new states were observed in the region of 1.7 to 2.5 MeV. They can be used to detect or assay {sup 237}Np nondestructively for applications in security and safeguards. The states are populated with similar strength as those states found previously in {sup 235}U and {sup 239}Pu but are spread out more in energy.

  6. 237Np absolute delayed neutron yield measurements

    NASA Astrophysics Data System (ADS)

    Doré, D.; Ledoux, X.; Nolte, R.; Gagnon-Moisan, F.; Thulliez, L.; Litaize, O.; Roettger, S.; Serot, O.

    2017-09-01

    237Np absolute delayed neutron yields have been measured at different incident neutron energies from 1.5 to 16 MeV. The experiment was performed at the Physikalisch-Technische Bundesanstalt (PTB) facility where the Van de Graaff accelerator and the cyclotron CV28 delivered 9 different neutron energy beams using p+T, d+D and d+T reactions. The detection system is made up of twelve 3He tubes inserted into a polyethylene cylinder. In this paper, the experimental setup and the data analysis method are described. The evolution of the absolute DN yields as a function of the neutron incident beam energies are presented and compared to experimental data found in the literature and data from the libraries.

  7. Interpretation of the 231Pa/ 230Th paleocirculation proxy: New water-column measurements from the southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Thomas, Alex L.; Henderson, Gideon M.; Robinson, Laura F.

    2006-01-01

    Measurements of 231Pa, 230Th and 232Th concentrations have been made on five water-column profiles along the western margin of the Madagascar and Mascarene Basins in the southern Indian Ocean. These measurements help to fill a significant gap in the global coverage of water-column 232Th, 230Th and 231Pa data. 232Th concentrations vary, but generally increase with depth, suggesting higher particle loading in deeper waters, and the presence of a significant dissolved fraction of 232Th. 230Th concentrations increase with depth, and profiles are similar to the average of existing data from other regions. 231Pa concentrations, on the other hand, show significant depth structure, apparently reflecting the various water masses sampled at this location. The modified remnants of North Atlantic Deep Water are found at a depth of ≈ 2000 m and exhibit elevated 231Pa concentrations exported from the South Atlantic. Antarctic Intermediate and Bottom Waters have lower 231Pa, probably due to scavenging onto opal particles during transit from the Southern Ocean. The differences between water masses raises a question: which water mass is important in controlling the 231Pa/ 230Th ratio in underlying sediments? A simple one-dimensional model is used to demonstrate that the 230Th and 231Pa exported to sea-floor sediments last equilibrates with waters close to the seafloor (within ≈ 1000 m), rather than averaging the whole water column. These findings suggest that 231Pa xs/ 230Th xs in sediments provides information primarily about deep-water masses. In this region, sedimentary records will therefore provide information about the past flow of Antarctic Bottom Water into the Indian Ocean. Interpretation of data from other regions, such as the North Atlantic where this proxy has most successfully been applied, requires careful consideration of regional oceanography and knowledge of the composition of the water masses being investigated.

  8. {sup 231}Pa photofission cross section

    SciTech Connect

    Soldatov, A.S.; Rudnikov, V.E.; Smirenkin, G.N.

    1995-12-01

    The measurements of the {sup 231}Pa yield and cross section photofission in the energy range 7-9 MeV are presented. These measurements are a continuation of similar measurements performed for the {gamma}-ray energy range 4.8-7 MeV. The entire collection of experimental data which combine the results obtained in the present work and in Ref. 1 was analyzed.

  9. Updated and revised neutron reaction data for 237Np

    NASA Astrophysics Data System (ADS)

    Chen, Guochang; Wang, Jimin; Cao, Wentian; Tang, Guoyou; Yu, Baosheng

    2017-09-01

    Nuclear data with high accuracy for minor actinides play an important role in nuclear technology applications, including reactor design and operation, fuel cycle, estimation of the amount of minor actinides in high burn-up reactors and the minor actinides transmutation. Based on the evaluated experimental data, the updated and revised evaluation of a full set of n+237Np nuclear data from 10-5 eV ˜ 20 MeV are carried out and recommended. Mainly revised quantities are neutron multiplicities from fission reaction, inelastic, fission, (n, 2n) and (n, γ) reaction cross sections as well as angular distribution and so on. The promising results are obtained when the renewal evaluated data of 237Np will be used to instead of the evaluated data in CENDL-3.1 database.

  10. Global distribution of Pu isotopes and 237Np.

    PubMed

    Kelley, J M; Bond, L A; Beasley, T M

    1999-09-30

    Inventories and compositions of Pu isotopes and 237Np in archived soil samples collected in the 1970s from 54 locations around the world were determined to provide regional baselines for recognizing possible future environmental inputs of non-fallout Pu and Np. As sample sizes used in this work were small (typically 1 g), inhomogeneities in Pu and Np concentrations were easily recognizable and, as a result, we were able to determine that atypical debris in South America, from French testing in the South Pacific, is more widely and uniformly distributed than previously supposed. From our results we conclude that fallout 237Np/239Pu atom ratios are generally lower in the Southern Hemisphere (approximately 0.35) than in the Northern Hemisphere (approximately 0.47.) Moreover, 237Np/239Pu atom ratios are more device-dependent, hence more variable, than counterpart 240Pu/239Pu atom ratios. Given predictable trends caused by sample inhomogeneities, with only two exceptions, the Pu results of this work are entirely consistent with (and in several instances improve on) results previously reported for these same samples. However, unlike earlier interpretations used to explain these results, we recommend that fallout isotopic signatures be represented by mixing lines, rather than averages, to better reflect regional variations of stratospheric fallout inventories relative to tropospheric fallout inventories, and provide the theoretical basis for doing so. Finally, the Np results of this work constitute one of the largest single compilations of such data reported to date.

  11. 237 Np Mössbauer isomer shifts in neptunium chalcogenides

    NASA Astrophysics Data System (ADS)

    Thévenin, T.; Jové, J.; Pagès, M.

    1984-10-01

    We report237Np Mössbauer spectrometry measurements on some Np polychalcogenides: NpS3, β-NpS2, Np3Se5, NpTe3, α-Np2S3 and γ-Np2Se3. The experiments have been performed at 4.2 K and 77 K. From the isomeric shift values, the oxidation state of the Np ion can easily be assigned in these kinds of compounds: Np(IV) in NpS3, β-NpS2 and Np(III) in NpTe3, α-Np2S3 and γ-Np2 Se3. A mixture of Np(III) and Np(IV) ions has been observed in Np3Se5. Comparisons of the IS values have pointed out the influence of the electronegativity of the chalcogen atom and of the bond length Np- X(X≡ S, Se, Te).

  12. {sup 237}Np: Oxidation state in vivo and chelation by multidentate catecholat and hydroxypyridinonate ligands

    SciTech Connect

    Durbin, P.W.; Kullgren, B.; Allen, P.G.; Bucher, J.J.; Edelstein, N.M.; Shuh, D.K.; Xu, J.; Raymond, K.N. |

    1998-07-01

    Chemically, {sup 237}Np(V) is as toxic as U(VI), and radiologically, about as toxic as {sup 239}Pu. Depending on redox conditions in vivo, {sup 237}Np exists as weakly complexing Np(V) (NpO{sub 2}{sup +}) or as Np(IV), which forms complexes as stable as those of Pu(IV). Ten multidentate catecholate (CAM) and hydroxypyridinonate (HOPO) ligands with great affinity for Pu(IV) were compared with CaNa{sub 3}-DTPA for in vivo chelation of {sup 237}Np. Mice were injected intravenously with {sup 237}NpO{sub 2}Cl: those in a kinetic study were killed 1 to 2,880 min; in ligand studies, fed mice were injected intraperitoneally with a ligand 5, 60, or 1,440 min after {sup 237}Np(V), mice fasted for 16 h were gastrically intubated with a ligand 3 min after {sup 237}Np(V), and all were killed 24 h after ligand administration; tissues and excreta were radioanalyzed. Rapid plasma clearance and urinary excretion of {sup 237}Np(V) resemble U(VI); deposition and early retention in skeleton and liver resemble Pu(IV). The x-ray absorption near edge structure spectroscopy (XANES) spectra of femora of {sup 237}Np(V)-injected mice, compared with spectra of Np(V) and Np(IV) from reference solids, showed predominantly Np(IV). Significant in vivo {sup 237}Np chelation was obtained with all of the HOPO and CAM ligands injected at molar ratio 22; the HOPO ligands reduced {sup 237}Np in skeleton, liver, and other soft tissue, on average, to 72, 25, and 25% of control, respectively, while CaNa{sub 3}-DTPA was ineffective.

  13. Observations of 231Pa/ 235U disequilibrium in volcanic rocks

    NASA Astrophysics Data System (ADS)

    Pickett, David A.; Murrell, Michael T.

    1997-04-01

    We present here the first survey of ( 231Pa/ 235U) ratios in volcanic rocks; such measurements are made possible by new mass spectrometric techniques. The data place new constraints on the timing and extent of magma source and evolutionary processes, particularly due to the sensitivity of the 231Pa- 235U pair and its intermediate time scale ( 231Pat 1/2 = 33 ky). ( 231Pa/ 235U) is found to vary widely, from 0.2 in carbonatites to 1.1-2.9 in basalts and 0.9-2.2 in arcs. Substantial Pa enrichment is nearly ubiquitous, suggestive of the relative incompatibility of Pa, qualitatively consistent with available partitioning data. The level of 231Pa- 235U disequilibrium typically far exceeds that of 230Th- 238U and is comparable to 226Ra- 230Th. The high ( 231Pa/ 235U) ratios in MORB and other basalts reflect a large degree of discrimination between two incompatible elements, posing challenges for modelling of melt generation and migration. Fundamental differences in ( 231Pa/ 235U) among different basaltic environments are likely related to contrasts in melting zone conditions (e.g., melting rate). Strong ( 231Pa/ 235U) disequilibria in continental basalts, for which ( 230Th/ 238U) disequilibria are small or absent, demonstrate that Pa-U fractionation is possible in both garnet and spinel mantle stability fields. In arcs, correlation of ( 231Pa/ 235U) and ( 230Th/ 238U) is consistent with U enrichment via slab-derived fluids, a process which is additional to the still dominant Pa enrichment. An important new constraint is provided by the observation that the near-equilibrium ( 230Th/ 238U) common to arcs and continental basalts is not typically accompanied by near-equilibrium ( 231Pa/ 235U), arguing against the influence of long magma history, crustal material, or equilibrium mantle sources in affecting decay-series ratios. Small sample sets from two silicic centers illustrate: (1) recent, rapid U enrichment in the magma chamber (El Chichón); and (2) the failure of

  14. 231Pa systematics in postglacial volcanic rocks from Iceland

    NASA Astrophysics Data System (ADS)

    Turner, Simon; Kokfelt, Thomas; Hoernle, Kaj; Lundstrom, Craig; Hauff, Folkmar

    2016-07-01

    Several recent studies have highlighted the potential of combined 238U-230Th and 235U-231Pa systematics to constrain upwelling rates and the role of recycled mafic lithologies in mantle plume-derived basalts. Accordingly, we present measurements of the 231Pa concentrations from 26 mafic volcanic rocks from Iceland, including off-axis basalts from the Snaefellsnes Peninsula, to complement previously published 238U-230Th-226Ra data. 231Pa concentrations vary from 27 to 624 fg/g and (231Pa/235U) ratios from 1.12 to 2.11 with the exception of one anomalous sample from the Southeast Rift which has a 231Pa deficit with (231Pa/235U) = 0.86. An important new result is that basalts from the Southeast Rift and the Snaefellsnes Peninsula define a trend at relatively low (231Pa/235U) for a given (230Th/238U) ratio. Many of the remaining samples fall in or around the global field for ocean island basalts but those from the Mid-Iceland Belt and the Southwest Rift/Reykjanes Peninsula extend to higher (231Pa/235U) ratios at a given (230Th/238U), similar to mid-ocean ridge basalts. In principle, these lavas could result from melting of peridotite at lower pressures. However, there is no reason to suspect that the Mid-Iceland Belt and the Southwest Rift lavas reflect shallower melting than elsewhere in Iceland. In our preferred model, these lavas reflect melting of garnet peridotite whereas those from the Southeast Rift and the Snaefellsnes Peninsula contain a significant contribution (up to 20%) of melt from garnet pyroxenite. This is consistent with incompatible trace element and radiogenic isotope evidence for recycled oceanic crust in these lavas. There is increasing agreement that the displacement of ocean island basalts to lower (231Pa/235U) ratios at a given (230Th/238U), compared to mid-ocean ridge basalts, reflects the role of recycled mafic lithologies such as garnet pyroxenite as well as higher average pressures of melting. It now seems likely that this interpretation may

  15. Study on migration behaviour of 237Np and 241Am in near-surface environments.

    PubMed

    Tanaka, Tadao; Ya-Anant, Nanthavan

    2011-07-01

    Laboratory-scale experiments were performed to investigate migration behaviour of (237)Np and (241)Am, which were deposited onto the ground surface from spent fuel reprocessing facilities. Migration experiments by column method were conducted for a sandy soil and a reddish soil by varying the volume of eluting solution. There seemed to be two chemical species of (237)Np in the sandy soil column: one is cationic and the other is particulate form. The particulates moved without significant interaction with the sandy soil. The sorption of cationic (237)Np was controlled by both a reversible ion-exchange reaction and irreversible reactions. Most of (241)Am was formed into rather large particulates and trapped in the sandy soil column. The (237)Np and (241)Am loaded into the reddish soil column moved deeper with increasing eluting volume. The sorption was mainly controlled by ion-exchange reaction. The migration behaviour might be evaluated by the distribution coefficient.

  16. (237)Np analytical method using (239)Np tracers and application to a contaminated nuclear disposal facility.

    PubMed

    Snow, Mathew S; Morrison, Samuel S; Clark, Sue B; Olson, John E; Watrous, Matthew G

    2017-06-01

    Environmental (237)Np analyses are challenged by low (237)Np concentrations and lack of an available yield tracer; we report a rapid, inexpensive (237)Np analytical approach employing the short lived (239)Np (t1/2 = 2.3 days) as a chemical yield tracer followed by (237)Np quantification using inductively coupled plasma-mass spectrometry. (239)Np tracer is obtained via separation from a (243)Am stock solution and standardized using gamma spectrometry immediately prior to sample processing. Rapid digestions using a commercial, 900 W "Walmart" microwave and Parr microwave vessels result in 99.8 ± 0.1% digestion yields, while chromatographic separations enable Np/U separation factors on the order of 10(6) and total Np yields of 95 ± 4% (2σ). Application of this method to legacy soil samples surrounding a radioactive disposal facility (the Subsurface Disposal Area at Idaho National Laboratory) reveal the presence of low level (237)Np contamination within 600 m of this site, with maximum (237)Np concentrations on the order of 10(3) times greater than nuclear weapons testing fallout levels. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. 237Np analytical method using 239Np tracers and application to a contaminated nuclear disposal facility

    DOE PAGES

    Snow, Mathew S.; Morrison, Samuel S.; Clark, Sue B.; ...

    2017-03-21

    In this study, environmental 237Np analyses are challenged by low 237Np concentrations and lack of an available yield tracer; we report a rapid, inexpensive 237Np analytical approach employing the short lived 239Np (t1/2 = 2.3 days) as a chemical yield tracer followed by 237Np quantification using inductively coupled plasma-mass spectrometry. 239Np tracer is obtained via separation from a 243Am stock solution and standardized using gamma spectrometry immediately prior to sample processing. Rapid digestions using a commercial, 900 W "Walmart" microwave and Parr microwave vessels result in 99.8 ± 0.1% digestion yields, while chromatographic separations enable Np/U separation factors on themore » order of 106 and total Np yields of 95 ± 4% (2σ). Application of this method to legacy soil samples surrounding a radioactive disposal facility (the Subsurface Disposal Area at Idaho National Laboratory) reveal the presence of low level 237Np contamination within 600 m of this site, with maximum 237Np concentrations on the order of 103 times greater than nuclear weapons testing fallout levels.« less

  18. Status of the Neutron Capture Measurement on 237Np with the DANCE Array at LANSCE

    SciTech Connect

    Esch, E.-I.; Bond, E.M.; Bredeweg, T. A.; Glover, S. E.; Haight, R. C.; Kronenberg, A.; O'Donnell, J. M.; Pitcher, E. J.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wender, S. A.; Wouters, J. M.; Alpizar-Vicente, A.; Greife, U.; Hatarik, R.

    2005-05-24

    Neptunium-237 is a major constituent of spent nuclear fuel. Estimates place the amount of 237Np bound for the Yucca Mountain high-level waste repository at 40 metric tons. The Department of Energy's Advanced Fuel Cycle Initiative program is evaluating methods for transmuting the actinide waste that will be generated by future operation of commercial nuclear power plants. The critical parameter that defines the transmutation efficiency of actinide isotopes is the neutron fission-to-capture ratio for the particular isotope in a given neutron spectrum. The calculation of transmutation efficiency therefore requires accurate fission and capture cross sections. Current 237Np evaluations available for transmuter system studies show significant discrepancies in both the fission and capture cross sections in the energy regions of interest. Herein we report on 237Np (n,{gamma}) measurements using the recently commissioned DANCE array.

  19. 237Np and 57Fe Mössbauer study of NpFeGa5

    NASA Astrophysics Data System (ADS)

    Homma, Y.; Nakada, M.; Nakamura, A.; Nasu, S.; Aoki, D.; Sakai, H.; Ikeda, S.; Yamamoto, E.; Haga, Y.; Ōnuki, Y.; Shiokawa, Y.

    2006-02-01

    57Fe and 237Np Mössbauer Ōmeasurements have been performed for NpFeGa5, which is one of the so-called neptunium 1-1-5 compounds. The 57Fe Mössbauer spectra below T N = 118 K show the magnetically ordered state. The magnitude of the hyperfine magnetic field at the 57Fe nucleus is determined to be 1.98 ± 0.05 T at 10 K. From the 237Np Mössbauer spectrum at 10 K, the hyperfine magnetic field at the 237Np nucleus is 203 T and the hyperfine coupling constant is determined to be 237 T/μB using the Np atomic magnetic moment of 0.86 μB determined by the neutron diffraction study.

  20. 237Np and 57Fe Mdssbauer study of NpFeGa5

    NASA Astrophysics Data System (ADS)

    Homma, Y.; Nakada, M.; Nakamura, A.; Nasu, S.; Aoki, D.; Sakai, H.; Ikeda, S.; Yamamoto, E.; Haga, Y.; Onuki, Y.; Shiokawa, Y.

    57Fe and 237Np Mössbauer Omeasurements have been performed for NpFeGa5, which is one of the so-called neptunium 1-1-5 compounds. The 57Fe Mössbauer spectra below T N=118 K show the magnetically ordered state. The magnitude of the hyperfine magnetic field at the 57Fe nucleus is determined to be 1.98 ± 0.05 T at 10K. From the 237Np Mössbauer spectrum at 10 K, the hyperfine magnetic field at the 237Np nucleus is 203 T and the hyperfine coupling constant is determined to be 237 T/μB using the Np atomic magnetic moment of 0.86 μB determined by the neutron diffraction study.

  1. Status of the Neutron Capture Measurement on 237Np with the DANCE Array at LANSCE

    NASA Astrophysics Data System (ADS)

    Esch, E.-I.; Alpizar-Vicente, A.; Bond, E. M.; Bredeweg, T. A.; Glover, S. E.; Greife, U.; Haight, R. C.; Hatarik, R.; Kronenberg, A.; O'Donnell, J. M.; Pitcher, E. J.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wender, S. A.; Wouters, J. M.

    2005-05-01

    Neptunium-237 is a major constituent of spent nuclear fuel. Estimates place the amount of 237Np bound for the Yucca Mountain high-level waste repository at 40 metric tons. The Department of Energy's Advanced Fuel Cycle Initiative program is evaluating methods for transmuting the actinide waste that will be generated by future operation of commercial nuclear power plants. The critical parameter that defines the transmutation efficiency of actinide isotopes is the neutron fission-to-capture ratio for the particular isotope in a given neutron spectrum. The calculation of transmutation efficiency therefore requires accurate fission and capture cross sections. Current 237Np evaluations available for transmuter system studies show significant discrepancies in both the fission and capture cross sections in the energy regions of interest. Herein we report on 237Np (n,γ) measurements using the recently commissioned DANCE array.

  2. Reliable determination of 237Np in environmental solid samples using 242Pu as a potential tracer.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Roos, Per; Miró, Manuel

    2011-04-15

    This paper reports an analytical method for rapid determination of neptunium ((237)Np) in environmental solid samples exploiting automated sequential injection (SI)-based anion exchange separation. Pivotal issues on analytical method performance were investigated including sorption behavior of (237)Np onto various AG 1-type anion exchangers; suitability of (242)Pu as a tracer for (237)Np determination in environmental solid samples; and long-term chemical stability of tetravalent Np. Experimental results revealed that the degree of resin cross-linking has a significant influence on the separation efficiency in terms of chemical yields of (237)Np and removal of interfering nuclides. Although ca. 30% of sorbed Np onto AG 1- × 4 was stripped out during HCl rinsing step for the removal of Th, chemical yield ratios of (237)Np to (242)Pu were proven steady with an average value of 0.67 ± 0.04 (n=15) under selected experimental conditions. Disulfite-8M HNO(3) was selected as a redox pair for valence adjustment to Np(IV) and the tetravalent Np in the sample solution was demonstrated to be stabilized for up to 5 days under 3°C. The analytical results for reference materials showed a good agreement with the expected values, thereby demonstrating the usefulness of (242)Pu as a non-isotopic tracer for (237)Np chemical yield monitoring. The on-column separation procedure fosters rapid analysis as required in emergency situations since each individual sample can be handled within 2.5h, and leads to a significant decrease in labor intensity compared to conventional batch-wise protocols.

  3. Analysis of the 237Np-233Pa photon spectrum using the full response function method.

    PubMed

    Shchukin, G; Iakovlev, K; Morel, J

    2004-01-01

    A study has been made of X- and gamma-ray emission from 237Np in equilibrium with 233Pa using the full response function method. This analysis process is characterised by photon spectrometry in which the entire spectrum is modelled in a pseudo-empirical way by means of elementary functions describing the total absorption and escape peaks, the Compton diffusion internal and external to the detector and the peaks resulting from detection of internal conversion electrons. This method has been applied to determine the L X-, K X- and gamma-rays emission probabilities in 237Np and 233Pa decay studies.

  4. The 237Np(n,f) cross section at the CERN n-TOF facility

    NASA Astrophysics Data System (ADS)

    Karadimos, D.; Vlastou, R.; Vlachoudis, V.; Pavlopoulos, P.; Konovalov, V.; Diakaki, M.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvár, F.; Benlliure, J.; Berthoumieux, E.; Calviño, F.; Cano-Ott, D.; Capote, R.; de Albornoz, A. Carrillo; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Cortina, D.; Couture, A.; Cox, J.; David, S.; Dolfini, R.; Domingo-Pardo, C.; Dorochenko, A.; Dridi, W.; Duran, I.; Eleftheriadis, Ch.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; Gallino, R.; Cennini, P.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karamanis, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Kolokolov, D.; Kossionides, E.; Krticka, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Sedysheva, M.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Voss, F.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2011-10-01

    The 237Np(n,f) cross sections have been measured at the n-TOF facility relative to the 235U and 238U fission cross sections. The n-TOF spallation neutron source at CERN is characterized by a high intensity flux, an excellent time resolution and an extensive neutron energy range (from eV to GeV). A fast ionization chamber was used as a fission fragment detector with efficiency better than 97%. Preliminary 237Np(n,f) cross sections have been deduced in the energy range from 20 keV to 10 MeV and are found in good agreement with data from literature.

  5. Radiochemical determination of 237NP in soil samples contaminated with weapon grade plutonium

    NASA Astrophysics Data System (ADS)

    Antón, M. P.; Espinosa, A.; Aragón, A.

    2006-01-01

    The Palomares terrestrial ecosystem (Spain) constitutes a natural laboratory to study transuranics. This scenario is partially contaminated with weapon-grade plutonium since the burnout and fragmentation of two thermonuclear bombs accidentally dropped in 1966. While performing radiometric measurements in the field, the possible presence of 237Np was observed through its 29 keV gamma emission. To accomplish a detailed characterization of the source term in the contaminated area using the isotopic ratios Pu-Am-Np, the radiochemical isolation and quantification by alpha spectrometry of 237Np was initiated. The selected radiochemical procedure involves separation of Np from Am, U and Pu with ionic resins, given that in soil samples from Palomares 239+240Pu levels are several orders of magnitude higher than 237Np. Then neptunium is isolated using TEVA organic resins. After electrodeposition, quantification is performed by alpha spectrometry. Different tests were done with blank solutions spiked with 236Pu and 237Np, solutions resulting from the total dissolution of radioactive particles and soil samples. Results indicate that the optimal sequential radionuclide separation order is Pu-Np, with decontamination percentages obtained with the ionic resins ranging from 98% to 100%. Also, the addition of NaNO2 has proved to be necessary, acting as a stabilizer of Pu-Np valences.

  6. Measurement of delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons

    SciTech Connect

    Gundorin, N. A.; Zhdanova, K. V.; Zhuchko, V. E.; Pikelner, L. B. Rebrova, N. V.; Salamatin, I. M.; Smirnov, V. I.; Furman, V. I.

    2007-06-15

    The delayed-neutron yield from thermal-neutron-induced fission of the {sup 237}Np nucleus was measured using a sample periodically exposed to a pulsed neutron beam with subsequent detection of neutrons during the time intervals between pulses. The experiment was realized on an Isomer-M setup mounted in the IBR-2 pulsed reactor channel equipped with a mirror neutron guide. The setup and the experimental procedure are described, the background sources are thoroughly analyzed, and the experimental data are presented. The total delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons is {nu}{sub d} = 0.0110 {+-} 0.0009. This study was performed at the Frank Laboratory of Neutron Physics (JINR, Dubna)

  7. The {sup 237}Np(n,f) cross section at the CERN n-TOF facility

    SciTech Connect

    Karadimos, D.; Vlastou, R.; Diakaki, M.; Papadopoulos, C.; Vlachoudis, V.; Chiaveri, E.; Ferrari, A.; Fitzpatrick, L.; Cennini, P.; Herrera-Martinez, A.; Kadi, Y.; Mengoni, A.; Sarchiapone, L.; Wendler, H.; Pavlopoulos, P.; Konovalov, V.; Furman, W.; Sedysheva, M.; Abbondanno, U.; Milazzo, P. M.

    2011-10-28

    The {sup 237}Np(n,f) cross sections have been measured at the n-TOF facility relative to the {sup 235}U and {sup 238}U fission cross sections. The n-TOF spallation neutron source at CERN is characterized by a high intensity flux, an excellent time resolution and an extensive neutron energy range (from eV to GeV). A fast ionization chamber was used as a fission fragment detector with efficiency better than 97%. Preliminary {sup 237}Np(n,f) cross sections have been deduced in the energy range from 20 keV to 10 MeV and are found in good agreement with data from literature.

  8. 237Np Mössbauer studies on actinide superconductors and related materials

    NASA Astrophysics Data System (ADS)

    Colineau, Eric; Gaczyński, Piotr; Griveau, Jean-Christophe; Eloirdi, Rachel; Caciuffo, Roberto

    2012-03-01

    Actinide materials play a special role in condensed matter physics, spanning behaviours of itinerant d-electron and localized 4f-electron materials. This duality of the 5f electrons confer to actinide-based intermetallic compounds a broad variety of physical properties such as magnetic or multipolar ordering, heavy fermion behaviour, quantum criticality, unconventional superconductivity... 237Np Mössbauer spectroscopy is a unique microscopic tool for gaining information on the electronic and magnetic properties of Np systems.

  9. Perturbed angular distribution of 237Np gamma rays from the 237U parent

    NASA Astrophysics Data System (ADS)

    Ansaldo, Eduardo J.

    1980-09-01

    The anisotropy was measured for the 208.0-59.54 keV gamma cascade in 237Np, corresponding to a positive sign for the M1-E2 mixing ratio of the 208.0 keV transition. The sources were prepared by means of the 238U(e, n) reaction. A discussion on the implications of the present results for the study of hyperfine interactions in neptunium compounds and alloys is included.

  10. Standardization and photon emission probabilities in the decay of 237Np/233Pa

    PubMed

    Schotzig; Schonfeld; Janszen

    2000-04-01

    The activity concentration of a 237Np solution was determined by 4pialpha counting, by alpha particle spectroscopy with defined solid angle and by liquid scintillation counting (LSC). These methods yielded results which differ by less than 0.1% from the mean, the relative standard uncertainties being 0.23% (4pialpha), 0.27% (LSC) and 0.5% (solid angle). X-ray and gamma-ray emission probabilities of several transitions were measured using semiconductor detectors.

  11. Nuclear Resonance Fluorescence Measurements on ^237Np for Security and Safeguards Applications

    NASA Astrophysics Data System (ADS)

    Angell, C. T.; Joshi, T.; Yee, Ryan; Norman, E. B.; Kulp, W. D.; Warren, G. A.; Korbly, S.; Klimenko, A.; Wilson, C.; Copping, R.; Shuh, D. K.

    2009-10-01

    The smuggling of nuclear material and the diversion of fissile material for covert weapon programs both present grave risks to world security. Methods are needed to detect nuclear material smuggled in cargo, and for proper material accountability in civilian fuel re-processing facilities. Nuclear resonance fluorescence (NRF) is a technique that can address both needs. It is a non-destructive active interrogation method that provides isotope-specific information. It works by using a γ-ray beam to resonantly excite levels in a nucleus and observing the γ-rays emitted whose energy and intensity are characteristic of that isotope. ^237Np presents significant safeguard challenges; it is fissile yet currently has fewer safeguard restrictions. NRF measurements on ^237Np will expand the nuclear database and will permit designing interrogation and assay systems. Measurements were made using the bremsstrahlung beam at the HVRL at MIT on a 7 g target of ^237Np with two incident electron energies of 2.8 and 3.1 MeV. Results will be presented with discussion of the relevant nuclear structure necessary to predict levels in other actinides.

  12. RAPID SEPARATION METHOD FOR 237NP AND PU ISOTOPES IN LARGE SOIL SAMPLES

    SciTech Connect

    Maxwell, S.; Culligan, B.; Noyes, G.

    2010-07-26

    A new rapid method for the determination of {sup 237}Np and Pu isotopes in soil and sediment samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for large soil samples. The new soil method utilizes an acid leaching method, iron/titanium hydroxide precipitation, a lanthanum fluoride soil matrix removal step, and a rapid column separation process with TEVA Resin. The large soil matrix is removed easily and rapidly using this two simple precipitations with high chemical recoveries and effective removal of interferences. Vacuum box technology and rapid flow rates are used to reduce analytical time.

  13. (237)Np(n,f) Cross Section: New Data and Present Status

    SciTech Connect

    Paradela, C.; Koehler, Paul Edward; N_TOF collaboration,

    2011-01-01

    In this document, we present the final result obtained at the n-TOF experiment for the neutron-induced fission cross section of the {sup 237}Np, from the fission threshold up to 1 GeV. The method applied to get this result is briefly discussed. n-TOF data are compared to the last experimental measurements using other TOF facilities or the surrogate method, reported experiments performed with monoenergetic sources and the FISCAL systematic, including a discussion about the existing discrepancies.

  14. 231Pa/230Th records of Arctic/Atlantic interchange in Fram Strait

    NASA Astrophysics Data System (ADS)

    Hoffmann, S. S.; McDermott, K. J.; McManus, J. F.; Mukasa, S. B.

    2014-12-01

    Fram Strait, the Arctic Ocean's only deep passage for exchange with lower latitude oceans, today serves as a conduit for waters flowing north into the Arctic Ocean and south into the Atlantic. Reconstruction of circulation patterns and strength at depth in the strait can help to clarify the history of Arctic/Atlantic deep water exchange and Arctic contributions to global meridional overturning circulation. We will present new sedimentary measurements of radioisotopes 231Pa and 230Th to provide information on this exchange in the past and its relationship to sedimentation and climatic events. Coretop and downcore 231Pa/230Th ratios from Arctic sediments indicate that 231Pa has been exported from the central Arctic basin throughout the Holocene and deglaciation. Fram Strait represents a possible sink for this "missing" 231Pa. Preliminary results from ODP Holes 908A and 909A, at 1274 m and 2519 m water depths respectively in the central strait, suggest that ratios in this region during the Holocene have varied between ~0.106 (above the 231Pa/230Th production ratio of 0.093 in seawater, indicating net import of 231Pa)and ~0.055 (well below the production ratio, indicating net export of 231Pa). Further measurements in cores from the Greenland and Svalbard continental slopes will give a fuller regional picture of 231Pa deposition and transport across the strait.

  15. (237)Np Mössbauer effect study on NpFeAsO.

    PubMed

    Gaczyński, P; Klimczuk, T; Walker, H; Springell, R; Colineau, E; Eloirdi, R; Griveau, J-C; Caciuffo, R

    2014-04-16

    We report (237)Np Mössbauer measurements on NpFeAsO. The Np atoms were found to occupy only one crystallographic site. The value of the isomer shift (δ ∼ 9.1 mm s(-1) versus NpAl2) indicates a 5f(4) electronic configuration (Np(3+) ions). The magnetic ordering of the Np sublattice below 60 K is established and the saturated ordered magnetic moment is determined to be 1.73μB at 3.6 K. The unique set of hyperfine parameters exclude a modulated magnetic structure or spin waves on the Np site. The neptunium magnetic moments μNp are found to lie along the tetragonal c-axis.

  16. 237Np Mössbauer spectroscopy on neptunium doped borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Bogé, M.; Blaise, A.; Bonnisseau, D.; Fournier, J. M.; Thérond, P. G.; Poirot, I.; Beauvy, M.

    1986-02-01

    Mössbauer and magnetization measurements have been carried out on borosilicate glasses containing neptunium. Different melting and annealing times, in various crucibles have been investigated. Using the 59.5 keV Mössbauer resonance in237Np we have characterized valency states of neptunium ions in glasses and studied hyperfine interactions. Roughly, absorption spectra show two sites easily differenciated above 50 K by two lines. Isomer shifts (relative to NpAl2) are respectively: - 10.0 (1.0) and + 32.5(.5) mm/s. These resonance lines can be assigned, the first at Np4+, the second at Np3+ species. The intensity ratio Np4+/Np3+ varies with elaboration conditions. At 4.2 K, Np4+ ions exhibit a hyperfine splitting arising from relaxation phenomenon. Magnetization measurements do not show any magnetic ordering.

  17. Role of transitional levels in {sup 237}Np ({gamma},f): Perspectives for studying highly deformed systems

    SciTech Connect

    Arruda-Neto, J. D. T.; Garcia, F.; Rodriguez, O.; Geraldo, L. P.; Rodrigues, T. E.; Shtejer, K.; Semmler, R.

    2006-09-15

    The transition levels at the top of the two {sup 237}Np fission barriers were obtained for the first time by means of the so-called semimicroscopic combined method, which we have developed and implemented. To overcome the difficulties in dealing with large nuclear deformations, we used our developed BARRIER code, which calculates single-particle spectra in a deformed Woods-Saxon potential using a coordinate system based on Cassini ovaloids as nuclear shape parametrization. The results enabled us to describe the experimentally observed near-barrier photofission cross-section structures for {sup 237}Np, as well as a subbarrier shelf, the latter being consistently interpreted in terms of the accumulation of levels at the top of the inner and outer double fission barrier of {sup 237}Np.

  18. Coulomb excitation of states in 232Th

    NASA Astrophysics Data System (ADS)

    McGowan, F. K.; Milner, W. T.

    1993-09-01

    Twenty-five states in 232Th have been observed with 18 MeV 4He ions on a thick target. Eleven 2 + states between 774 and 1554 keV and three 3 - states are populated by direct E2 and E3, respectively. The remaining states are either weakly excited by multiple Coulomb excitation and/or populated by the decay of the directly excited states. Spin assignments are based on γ-ray angular distributions. Reduced transition probabilities have been deduced from the γ-ray yields. The B(E2) values for excitation of the 2 + states range from 0.024 to 3.5 W.u. (222 W.u. for the first 2 + state). For the 3 - states, the B(E3,0 → 3 -) values are 1.7, 11, and 24 W.u. A possible two-phonon state at 1554 keV, which is nearly harmonic, decays to four members of the one-phonon states, to the ground-state band, and to the K = 0 - octupole band. The B(E2) value for excitation of this state is 0.66 ± 0.05 W.u. and the B(E1) values for decay of this state are (2 and 6)×10 -4 W.u. The B(E2) values between two- and one-phonon vibrational states range between 16 and 53 W.u. which are an order of magnitude larger than the B(E2) values between the one- and zero-phonon states. This disagrees with our present understanding of collectivity in nuclei if this 2 + state is considered to be a collective two-phonon excitation. The 2 + states at 1477 and 1387 keV, which are also nearly harmonic, are possible candidates with two-phonon structure. The agreement between the experimental results and the microscopic calculations by Neergård and Vogel of the B(E3,0 → 3) for the 3 - members of the one-phonon octupole quadruplet is satisfactory when the Coriolis coupling between the states with K and K ± 1 is included. The B(E1) branching ratios for transitions from the 3 - and 1 - states to the ground-state band have large deviations from the Alaga-rule predictions. These deviations can be understood by the strong Coriolis coupling between the states of the octupole quadruplet in deformed nuclei.

  19. Determination of traces of 237Np in environmental samples by ICP-MS after separation using TOA extraction chromatography.

    PubMed

    Ji, Y Q; Li, J Y; Luo, S G; Wu, T; Liu, J L

    2001-09-01

    A simple, rapid, cost-efficient, and robust method for separation of 237Np with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analysis. The column efficiently retained 237Np in 2 mol L(-1) HNO3 medium and all of the 237Np was easily eluted with 0.02 mol L(-1) oxalic acid in 0.16 mol L(-1) HNO3 at 95 degrees C. The separated solutions were free from most matrix elements and were aspirated into the ICP-MS directly. The decontamination factor for 238U is more than 10(4). The instrumental detection limit for 237Np was 0.46 pg mL(-1), which corresponds to 1.2 x 10(-5) Bq mL(-1). The method is more rapid than traditional radiometric techniques. It is also considered to be more suitable for environmental monitoring than existing methods based on TOA.

  20. Determination of 237Np and Pu isotopes in large soil samples by inductively coupled plasma mass spectrometry.

    PubMed

    Maxwell, Sherrod L; Culligan, Brian K; Jones, Vernon D; Nichols, Sheldon T; Bernard, Maureen A; Noyes, Gary W

    2010-12-03

    A new method for the determination of (237)Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of (237)Np and Pu isotopes by ICP-MS. (238)U can interfere with (239)Pu measurement by ICP-MS as (238)UH(+) mass overlap and (237)Np via (238)U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1×10(6). Alpha spectrometry can also be applied so that the shorter-lived (238)Pu isotope can be measured successfully. (239) Pu, (242)Pu and (237)Np were measured by ICP-MS, while (236)Pu and (238)Pu were measured by alpha spectrometry. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. DETERMINATION OF 237NP AND PU ISOTOPES IN LARGE SOIL SAMPLES BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    SciTech Connect

    Maxwell, S.

    2010-07-26

    A new method for the determination of {sup 237}Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of {sup 237}Np and Pu isotopes by ICP-MS. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via {sup 238}U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1 x 10{sup 6}. Alpha spectrometry can also be applied so that the shorter-lived {sup 238}Pu isotope can be measured successfully. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu and {sup 238}Pu were measured by alpha spectrometry.

  2. 231Pa/ 230Th as a Paleocirculation Proxy in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Henderson, G. M.; Hickey, B. J.; Rae, J. W.; Thomas, A. L.

    2008-12-01

    Since its first application as a proxy for the rate of past ocean circulation more than a decade ago (Yu et al. 1996), 231Pa/ 230Th has been applied predominantly to cores in the North Atlantic. At present, in this setting, the advection of surface waters to depth resets the 231Pa/ 230Th "clock" allowing the proxy to work, and the uniform southward movement of water masses make interpretation of sediment values relatively straightforward. The applicability of 231Pa/ 230Th in other settings, where water-masses may not be clearly reset, or where several water masses with different flow paths overlie one another remains unclear, but its use to reconstruct past flow rates in such settings would provide a powerful tool to understand past climate. We will present an overview of the potential for 231Pa/ 230Th use in the Southern Hemisphere, including new data from the Argentine basin. Data from the southern Indian Ocean (e.g. Thomas et al. 2007) demonstrate that advection of water to depth, and scavenging of 231Pa at the opal belt, effectively reset the 231Pa/ 230Th clock providing potential for application of the proxy to northward flowing water masses in the Southern Hemisphere. Modelling also indicates the sensitivity of Southern Hemisphere sediment 231Pa/ 230Th to changes in ocean circulation, particularly in the Argentine Basin (Siddall et al. 2007). We have investigated the use of the 231Pa/ 230Th proxy in four cores spanning all deep-water masses in that basin. The modern-day conditions in that basin are similar to those expected in the North Atlantic during the last glacial maximum with a southward and northward flowing water mass overlying one another. Results demonstrate that sediment 231Pa/ 230Th values vary significantly with water-mass throughout the last 20 kyr - offering the potential to reconstruct multiple water masses through time. Down-core results show variations that reflect changes in ocean circulation, but these are compounded with other effects

  3. Lung carcinogenesis in rats after inhalation exposure to (237)NpO2.

    PubMed

    Dudoignon, N; Guézingar-Liébard, F; Guillet, K; L'Hullier, I; Rateau, G; Monchaux, G; Fritsch, P

    1999-12-01

    The results of several studies of experimental carcinogenesis suggest that, after inhalation of alpha-particle emitters, lung tumor incidence varies depending on the exposure rate and dose distribution in the tissue. In the case of transuranics, the main influencing factor would be the specific alpha-particle activity of the inhaled actinide. To confirm these results, long-term studies were performed using male Sprague-Dawley rats exposed to (237)NpO(2) by inhalation. The initial lung burdens of the animals ranged from 0. 1 to about 7 kBq. The rats were followed during their life span and weighed regularly, and their lung burdens were determined in vivo and at death to estimate the lung dose. At death, the incidence of lung tumors and their malignancy and histological types were analyzed. The analysis revealed a typically linear-quadratic dose response for incidence of malignant lung neoplasm and a differential dose response for various types of tumors. Although these results confirm the influence of the activity of the inhaled actinide oxide, further experiments are needed to be able to compare a more homogeneous population of animals.

  4. Measurement and resonance analysis of the 237Np neutron capture cross section

    NASA Astrophysics Data System (ADS)

    Guerrero, C.; Cano-Ott, D.; Mendoza, E.; Abbondanno, U.; Aerts, G.; Álvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvár, F.; Belloni, F.; Berthoumieux, E.; Calviño, F.; Calviani, M.; Capote, R.; Carrapiço, C.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; González-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Ketlerov, V.; Kerveno, M.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krtička, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lossito, R.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Martínez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vicente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2012-04-01

    The neutron capture cross section of 237Np was measured between 0.7 and 500 eV at the CERN n_TOF facility using the 4π BaF2 Total Absorption Calorimeter. The experimental capture yield was extracted minimizing all the systematic uncertainties and was analyzed together with the most reliable transmission data available using the sammy code. The result is a complete set of individual as well as average resonance parameters [D0=0.56(2) eV, <Γγ>=40.9(18) meV, 104S0=0.98(6), R'=9.8(6) fm]. The capture cross section obtained in this work is in overall agreement with the evaluations and the data of Weston and Todd [Nucl. Sci. Eng. 79, 184 (1981)], thus showing sizable differences with respect to previous data from Scherbakov [J. Nucl. Sci. Technol. 42, 135 (2005)] and large discrepancies with data Kobayashi [J. Nucl. Sci. Technol.JNSTAX0022-313110.3327/jnst.39.111 39, 111 (2002)]. The results indicate that a new evaluation combining the present capture data with reliable transmission data would allow reaching an accuracy better than 4%, in line with the uncertainty requirements of the nuclear data community for the design and operation of current and future nuclear devices.

  5. Effect of DTPA on concentration ratios of /sup 237/Np and /sup 244/Cm in vegetative parts of bush bean and barley

    SciTech Connect

    Romney, E.M.; Wallace, A.; Mueller, R.T.; Cha, J.W.; Wood, R.A.

    1981-07-01

    We grew bush beans, barley, and rice in two different soils in a glasshouse with /sup 237/Np or /sup 244/Cm mixed into separate containers of the soil. The chelating agent DTPA at 100 ..mu..g/g soil was added to half of the containers. The concentration ratio (CR) for /sup 237/Np without DTPA was two orders of magnitude higher than for /sup 244/Cm without DTPA for all three plant species. The DTPA increased the CR of /sup 244/Cm by two to three orders of magnitude, but had no influence on that for /sup 237/Np. In bush beans, both /sup 237/Np and /sup 244/Cm CRs were higher in primary leaves than in trifoliate leaves, which were higher than for stems. The CRs for bush beans were generally higher for both /sup 237/Np and /sup 244/Cm than for either barley or rice, especially without DTPA.

  6. RAPID DETERMINATION OF 237 NP AND PU ISOTOPES IN WATER BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY

    SciTech Connect

    Maxwell, S.; Jones, V.; Culligan, B.; Nichols, S.; Noyes, G.

    2010-06-23

    A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of {sup 237}Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry; a hybrid approach. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4 to 6 hours, and can also be used for emergency response. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu, {sup 238}Pu, and {sup 239}Pu were measured by alpha spectrometry.

  7. 230Thand 231Pa in Seawater Sinking Particles from the North Atlantic GEOTRACES Transect

    NASA Astrophysics Data System (ADS)

    LU, Y.; Edwards, R. L.; Cheng, H.; Anderson, R. F.; Hayes, C. T.; Fleisher, M. Q.; Lam, P. J.; Huang, K. F.; Robinson, L. F.; Wang, X.

    2016-12-01

    The biological carbon pump in the ocean plays a key role in regulating atmospheric CO2 level via oceanic particle dynamics. Radionuclides with proper half-lives, like 230Th and 231Pa, can provide quantitative estimates of particle cycling on the timescales up to hundred thousand years. However, our understanding of particle dynamics is hindered by the difficulty in precisely determining particulate 230Th and 231Pa, due to the trace amounts of Th and Pa in seawater, especially in large sinking particles. Here, we developed a technique to measure sinking particulate 230Th and 231Pa in a small sample size (tens to hundreds attograms of 231Pa, equivalent to 100 L water pumped through QMA filter), and achieved an average precision in percentage level. We firstly applied leaching processes to the particulate samples. The samples were soaked in 8N HNO3 + 0.5N HF mixed with proportionally determined 229Th and 233Pa spikes, and heated at 100°C for 10 hours. Th and Pa were then pre-concentrated by co-precipitation with Fe. After HNO3-HClO4-HNO3 digestion of the precipitates, Th and Pa were separated and purified using anion exchange chromatography (Spectra/Gel anion resin 1x8). Pa was measured on a MC-ICP-MS instrument (Neptune) right after the chemistry in order to minimize the 233Pa "bleeding effect". Replication tests show a good agreement in 231Pa/230Th within the measurement uncertainties. Applying our method to the profile samples collected from the North Atlantic GEOTRACES Transect, we found that the concentrations of 230Th and 231Pa in sinking particles (>51 μm size fraction; attograms/liter) are about 1/10 of those in suspended ones (1 - 51 μm size fraction). The scavenging of Th and Pa to large particles appears to be a function of particle composition (CaCO3, POM, lithogenic, opal and Fe/Mn oxides). In addition, ratios of the adsorbed 231Pa to 230Th are the same in both types of particles, although the particles have significantly different residence time in

  8. 231Pa excesses in arc volcanic rocks: Constraint on melting rates at convergent margins

    NASA Astrophysics Data System (ADS)

    Huang, Fang; Lundstrom, Craig C.

    2007-11-01

    The 231Pa-235U disequilibria provide greater ability to constrain the rate of mantle melting in convergent margin settings than the more often analyzed 238U-230Th-226Ra systems, which are strongly affected by fluid-addition processes from the subducting slab. Here we present new 231Pa-235U data for 12 samples from the Kick'em Jenny (KEJ) submarine volcano in the Southern Lesser Antilles to define the melting rate at a subduction zone with one of the lowest convergence rates. The KEJ samples have the highest average (231Pa)/(235U) yet measured in global arcs, consistent with other studies of the Southern Lesser Antilles lavas. These results reinforce the previously noted negative correlation between average (231Pa)/(235U) and convergence rate in all arc settings globally. We develop a model to explain this negative correlation and to better constrain melting rates at convergent margins. Assuming that the corner flow velocity is coupled to and equal to the subducting slab velocity, the melting rate, directly reflecting the flux of water added, becomes a linear function of subduction rate. This physical model is then coupled to three different melting models previously developed for calculating U-series disequilibria (reactive porous flow, dynamic, and flux melting). All three models reproduce the globally observed negative correlation between subduction rate and 231Pa excess. Although the style of melting cannot be easily discriminated, the good correspondence between models and observation provides an example of how geochemical and geophysical models can be linked to provide a self-consistent model of melt generation in convergent margin settings.

  9. 231Pa and 233Pa Neutron-Induced Fission Data Analysis

    SciTech Connect

    Maslov, V.M.; Tetereva, N.A.; Baba, M.; Hasegawa, A.; Kornilov, N.V.; Kagalenko, A.B.

    2005-05-24

    The 231Pa and 233Pa neutron-induced fission cross-section database is analyzed within the Hauser-Feshbach approach. The consistency of neutron-induced fission cross-section data and data extracted from transfer reactions is investigated. The fission probabilities of Pa, fissioning in 231,233Pa(n,nf) reactions, are defined by fitting (3He,d) or (3He,t) transfer-reaction data. The present estimate of the 233Pa(n,f) fission cross section above the emissive fission threshold is supported by smooth level-density parameter systematics, validated in the case of the 231Pa(n,f) data description up to En =20 MeV.

  10. Radiation protection potential of MOX-fuel doped with 231Pa and Cs radioisotopes.

    PubMed

    Kryuchkov, E F; Glebov, V B; Apse, V A; Shmelev, A N

    2005-01-01

    The paper addresses the problem of MOX-fuel self-protection during full cycle of MOX-fuel management. Under conditions of the closed LWR cycle the proliferation-resistance levels were evaluated for fresh and spent MOX-fuel with 231Pa and Cs feed. As it follows from the paper results, combination of these two admixtures being doped into MOX-fuel is able to enhance the inherent radiation barrier and to weaken shortcomings of both proliferation deterrents.

  11. Production of 230U/226Th for targeted alpha therapy via proton irradiation of 231Pa.

    PubMed

    Morgenstern, Alfred; Lebeda, Ondrej; Stursa, Jan; Bruchertseifer, Frank; Capote, Roberto; McGinley, John; Rasmussen, Gert; Sin, Mihaela; Zielinska, Barbara; Apostolidis, Christos

    2008-11-15

    (230)U and its daughter nuclide (226)Th are novel therapeutic nuclides for application in targeted alpha-therapy of cancer. We have investigated the feasibility of producing (230)U/(226)Th via proton irradiation of (231)Pa according to the reaction (231)Pa(p,2n)(230)U. The experimental excitation function for this reaction is reported for the first time. Cross sections were measured using thin targets of (231)Pa prepared by electrodeposition and (230)U yields were analyzed using alpha-spectrometry. Beam parameters (energy and intensity) were determined both by calculation using a mathematical model based on measured beam orbits and beam current integrator and by parallel monitor reactions on copper foils using high-resolution gamma-spectrometry and IAEA recommended cross-section data. The measured cross sections are in good agreement with model calculations using the EMPIRE-II code and are sufficiently high for the production of (230)U/(226)Th in clinically relevant amounts. A highly effective separation process was developed to isolate clinical grade (230)U from irradiated protactinium oxide targets. Product purity was assessed using alpha- and gamma-spectrometry as well as ICPMS.

  12. Holocene Paleocirculation from 231Pa/230Th in Sediments from the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    McManus, J.; Francois, R.; Major, C.; Gherardi, J.; Hoffman, S.

    2004-12-01

    A new record of bulk sedimentary 231Pa/230Th excesses from core GGC5 on the Bermuda Rise has been produced by ICP-MS. The record reveals several aspects of the strength of the meridional overturning circulation during the last ten thousand years. Measurements of uranium, protactinium and thorium in the Holocene section recovered in GGC5 have been resolved at approximately 200-300 years, similar to the response time of excess 231Pa in the water column, and therefore should capture any large departure from modern values in the 231Pa/230Th indicator of paleocirculation. No dramatic increase in ratio or decrease in circulation is indicated by the data, which suggest vigorous overturning in the western basin of the North Atlantic since the end of the Younger Dryas. Instead of large changes in circulation, a series of oscillations punctuates the middle Holocene, indicating a variability of 10-20 percent in the rate of meridional overturning. Specific attention will be paid to millennial events postulated at 8.2 kyr, ~5 kyr, and in the most recent Holocene.

  13. High-Resolution Study of 237Np Fission Cross Section from 5 eV to 1 MeV

    NASA Astrophysics Data System (ADS)

    Furman, W.; Cennini, P.; Ketlerov, V.; Goverdovski, A.; Konovalov, V.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Bec̆vár̆, F.; Benlliure, J.; Berthoumieux, E.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrillo de Albornoz, A.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Cortina, D.; Couture, A.; Cox, J.; David, S.; Dolfini, R.; Domingo-Pardo, C.; Dorochenko, A.; Dridi, W.; Duran, I.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Guerrero, C.; Goncalves, I.; Gallino, R.; Gonzalez-Romero, E.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karamanis, D.; Karadimos, D.; Kerveno, M.; Koehler, P.; Kolokolov, D.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Sedysheva, M.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Wendler, H.; Wiescher, M.; N Tof Collaboration

    2005-05-01

    A series of measurements of 237Np fission cross section have been performed at the CERN spallation neutron facility n_TOF which covers a wide energy range from 1 eV up to 250 MeV. A fast ionization chamber (FIC) was used as a fission fragment detector with registration efficiency of not less than 97 %. Particular attention was paid to correct the fission cross section with use of 235U standard. Total experimental uncertainties are determined to be at the level of 3%. Analysis of the experimental data in the restricted neutron energy from 5 eV up to 1 MeV showed a systematic deviation from evaluated data (ENDF/B-VI). This discrepancy amounts to up to a factor 3 for resolved resonances in the neutron energy range of 5 eV - 2 KeV, and is in good agreement with some previous experiments. A similar disagreement at the level of 6-7% was found for higher energies around the threshold (En = 300 keV-1 MeV). This energy range is essential for the transmutation of neptunium in ADS or fast reactors. It is concluded that an updated evaluation of nuclear data for 237Np is required.

  14. Sequential injection method for rapid and simultaneous determination of 236U, 237Np, and Pu isotopes in seawater.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Steier, Peter; Golser, Robin

    2013-11-19

    An automated analytical method implemented in a novel dual-column tandem sequential injection (SI) system was developed for simultaneous determination of (236)U, (237)Np, (239)Pu, and (240)Pu in seawater samples. A combination of TEVA and UTEVA extraction chromatography was exploited to separate and purify target analytes, whereupon plutonium and neptunium were simultaneously isolated and purified on TEVA, while uranium was collected on UTEVA. The separation behavior of U, Np, and Pu on TEVA-UTEVA columns was investigated in detail in order to achieve high chemical yields and complete purification for the radionuclides of interest. (242)Pu was used as a chemical yield tracer for both plutonium and neptunium. (238)U was quantified in the sample before the separation for deducing the (236)U concentration from the measured (236)U/(238)U atomic ratio in the separated uranium target using accelerator mass spectrometry. Plutonium isotopes and (237)Np were measured using inductively coupled plasma mass spectrometry after separation. The analytical results indicate that the developed method is robust and efficient, providing satisfactory chemical yields (70-100%) of target analytes and relatively short analytical time (8 h/sample).

  15. Coulomb Excitation and Few Nucleon Transfer Reactions with ^209Bi Beams on ^237Np and ^241Am Targets

    NASA Astrophysics Data System (ADS)

    Abu Saleem, K.; Janssens, R. V. F.; Carpenter, M. P.; Kondev, F. G.; Ahmad, I.; Greene, J. P.; Caggiano, J.; Heinz, A.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Sonzogni, A.; Wiedenhoever, I.; Hackman, G.; Chowdhury, P.; Cline, D.; Wu, C.; Machiavelli, A. O.; Devlin, M.; Fotiades, N.; Seabury, E. H.

    2002-10-01

    Two separate Coloumb excitation measurements have been performed at ATLAS using Pb beams, at bombarding energies ˜ 15% above the Coulomb barrier, incident upon ^237Np and ^241Am targets. Using these reactions, γ-ray coincidence data were collected with the Gammasphere array. In both measurements, rotational bands built on a πi_13/2 configuration were observed to high-spin in the target nuclei. From these new data and those available for even- and odd-A U and Pu isotopes, we have concluded that the i_13/2 quasiprotons dominate the observed alignments in this mass region and that there is little contribution from aligning j_15/2 neutron pairs. This is unexpected based on Cranked Shell Model predictions which indicate that both quasiparticle pairs should be involved in the observed alignment processes.

  16. Measurements of absolute delayed neutron yield and group constants in the fast fission of {sup 235}U and {sup 237}Np

    SciTech Connect

    Loaiza, D.J.; Brunson, G.; Sanchez, R.; Butterfield, K.

    1998-03-01

    The delayed neutron activity resulting from the fast induced fission of {sup 235}U and {sup 237}Np has been studied. The six-group decay constants, relative abundances, and absolute yield of delayed neutrons from fast fission of {sup 235}U and {sup 237}Np were measured using the Godiva IV fast assembly at the Los Alamos Critical Experiments Facility. The absolute yield measured for {sup 235}U was 0.0163 {+-} 0.0008 neutron/fission. This value compares very well with the well-established Keepin absolute yield of 0.0165 {+-} 0.0005. The absolute yield value measured for {sup 237}Np was 0.0126 {+-} 0.0007. The measured delayed neutron parameters for {sup 235}U are corroborated with period (e-folding time) versus reactivity calculations.

  17. Rapid determination of (237)Np in soil samples by multi-collector inductively-coupled plasma mass spectrometry and gamma spectrometry.

    PubMed

    Yi, Xiaowei; Shi, Yanmei; Xu, Jiang; He, Xiaobing; Zhang, Haitao; Lin, Jianfeng

    A radiochemical procedure is developed for the determination of (237)Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. (239)Np (milked from (243)Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO3 solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. (239)Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the (237)Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the (237)Np activity concentration, the feasibility of the procedure was validated.

  18. New insights into cycling of 231Pa and 230Th in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Rempfer, Johannes; Stocker, Thomas F.; Joos, Fortunat; Lippold, Jörg; Jaccard, Samuel L.

    2017-06-01

    We use the Bern3D model of intermediate complexity to examine the marine cycle of isotopes 231Pa and 230Th and the relationship between the particle-bound ratio Pap /Thp and changes in the formation of the North Atlantic Deep Water (NADW). Model parameters describing reversible scavenging of isotopes by organic particles, opal, calcite and resuspended sediments were systematically varied and alternative sink parametrisations explored. It proves difficult to simultaneously achieve a good agreement with observations of dissolved and particle-associated concentrations of 231Pa and 230Th (Pad, Thd, Pap, Thp) as well as the particle-bound ratio Pap /Thp within the classical concept of reversible scavenging alone. Agreement between simulated and observed Pad, Thd and estimates of mean ocean residence times is improved by taking into account simplified representations of additional sinks at the sea floor (bottom scavenging) and at continental boundaries (boundary scavenging). We also find improved agreement between model and data by increasing lateral advection, in particular for Pad. These results point to the importance of sink processes that act in addition to reversible scavenging to shape the steady state distribution of 231Pa and, to a lesser degree, of 230Th. In transient experiments in which the strength of the Atlantic meridional overturning circulation (AMOC) is periodically turned on and off, we find a strong statistical relationship between variations in AMOC strength and Pap /Thp at great depths in the Northwest Atlantic region. These conclusions are robust across the range of sink parametrisations, that are consistent with estimates in the mean ocean residence time of 231Pa and 230Th. Our results indicate that the relationship between Pap /Thp and AMOC-strength may not be fundamentally affected by uncertainties in sink processes, at least on the large spatial and temporal scale considered here, and support the idea that changes in Pap /Thp in sediments of

  19. Interpreting 231Pa/230Th observations and changes in ocean circulation

    NASA Astrophysics Data System (ADS)

    Tretkoff, Ernie

    2011-05-01

    Understanding past changes in ocean circulation is important, because the ocean transports heat and changes in ocean circulation can affect climate. To better understand past ocean circulation changes, some researchers have used the ratio of two isotopes, protactinium-231 (231Pa) and thorium-230 (230Th), in sediments as a proxy to infer changes in the Atlantic meridional overturning circulation (AMOC). Some studies have suggested that AMOC during the climate fluctuations of the Last Glacial Maximum (LGM; ˜21,000-18,000 years ago) and Heinrich Event 1 (H1; ˜17,000-15,000 years ago) was different from modern AMOC.

  20. Age determination of highly enriched uranium: separation and analysis of 231Pa.

    PubMed

    Morgenstern, A; Apostolidis, C; Mayer, K

    2002-11-01

    An analytical procedure has been developed for the age determination of highly enriched uranium samples exploiting the mother/daughter pair 235U/231Pa. Protactinium is separated from bulk uranium through highly selective sorption to silica gel and is subsequently quantified using alpha-spectrometry. The method has been validated using uranium standard reference materials of known ages. It affords decontamination factors exceeding 2.5 x 10(7), overall recoveries in the range of 80-85%, and a combined uncertainty below 5%.

  1. Persistent export of 231Pa from the deep central Arctic Ocean over the past 35,000 years.

    PubMed

    Hoffmann, Sharon S; McManus, Jerry F; Curry, William B; Brown-Leger, L Susan

    2013-05-30

    The Arctic Ocean has an important role in Earth's climate, both through surface processes such as sea-ice formation and transport, and through the production and export of waters at depth that contribute to the global thermohaline circulation. Deciphering the deep Arctic Ocean's palaeo-oceanographic history is a crucial part of understanding its role in climatic change. Here we show that sedimentary ratios of the radionuclides thorium-230 ((230)Th) and protactinium-231 ((231)Pa), which are produced in sea water and removed by particle scavenging on timescales of decades to centuries, respectively, record consistent evidence for the export of (231)Pa from the deep Arctic and may indicate continuous deep-water exchange between the Arctic and Atlantic oceans throughout the past 35,000 years. Seven well-dated box-core records provide a comprehensive overview of (231)Pa and (230)Th burial in Arctic sediments during glacial, deglacial and interglacial conditions. Sedimentary (231)Pa/(230)Th ratios decrease nearly linearly with increasing water depth above the core sites, indicating efficient particle scavenging in the upper water column and greater influence of removal by lateral transport at depth. Although the measured (230)Th burial is in balance with its production in Arctic sea water, integrated depth profiles for all time intervals reveal a deficit in (231)Pa burial that can be balanced only by lateral export in the water column. Because no enhanced sink for (231)Pa has yet been found in the Arctic, our records suggest that deep-water exchange through the Fram strait may export (231)Pa. Such export may have continued for the past 35,000 years, suggesting a century-scale replacement time for deep waters in the Arctic Ocean since the most recent glaciation and a persistent contribution of Arctic waters to the global ocean circulation.

  2. Concurrent determination of 237Np and Pu isotopes using ICP-MS: analysis of NIST environmental matrix standard reference materials 4357, 1646a, and 2702.

    PubMed

    Matteson, Brent S; Hanson, Susan K; Miller, Jeffrey L; Oldham, Warren J

    2015-04-01

    An optimized method was developed to analyze environmental soil and sediment samples for (237)Np, (239)Pu, and (240)Pu by ICP-MS using a (242)Pu isotope dilution standard. The high yield, short time frame required for analysis, and the commercial availability of the (242)Pu tracer are significant advantages of the method. Control experiments designed to assess method uncertainty, including variation in inter-element fractionation that occurs during the purification protocol, suggest that the overall precision for measurements of (237)Np is typically on the order of ± 5%. Measurements of the (237)Np concentration in a Peruvian Soil blank (NIST SRM 4355) spiked with a known concentration of (237)Np tracer confirmed the accuracy of the method, agreeing well with the expected value. The method has been used to determine neptunium and plutonium concentrations in several environmental matrix standard reference materials available from NIST: SRM 4357 (Radioactivity Standard), SRM 1646a (Estuarine Sediment) and SRM 2702 (Inorganics in Marine Sediment). Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Neutron-induced transmutation reactions in 237Np, 238Pu, and 239Pu at the massive natural uranium spallation target

    NASA Astrophysics Data System (ADS)

    Zavorka, L.; Adam, J.; Baldin, A. A.; Caloun, P.; Chilap, V. V.; Furman, W. I.; Kadykov, M. G.; Khushvaktov, J.; Pronskikh, V. S.; Solnyshkin, A. A.; Sotnikov, V.; Stegailov, V. I.; Suchopar, M.; Tsoupko-Sitnikov, V. M.; Tyutyunnikov, S. I.; Voronko, V.; Vrzalova, J.

    2015-04-01

    Transmutation reactions in the 237Np, 238Pu, and 239Pu samples were investigated in the neutron field generated inside a massive (m = 512 kg) natural uranium spallation target. The uranium target assembly QUINTA was irradiated with the deuteron beams of kinetic energy 2, 4, and 8 GeV provided by the Nuclotron accelerator at the Joint Institute for Nuclear Research (JINR) in Dubna. The neutron-induced transmutation of the actinide samples was measured off-line by implementing methods of gamma-ray spectrometry with HPGe detectors. Results of measurement are expressed in the form of both the individual reaction rates and average fission transmutation rates. For the purpose of validation of radiation transport programs, the experimental results were compared with simulations of neutron production and distribution performed by the MCNPX 2.7 and MARS15 codes employing the INCL4-ABLA physics models and LAQGSM event generator, respectively. In general, a good agreement between the experimental and calculated reaction rates was found in the whole interval of provided beam energies.

  4. Proton induced fission of 232Th at intermediate energies

    NASA Astrophysics Data System (ADS)

    Gikal, K. B.; Kozulin, E. M.; Bogachev, A. A.; Burtebaev, N. T.; Edomskiy, A. V.; Itkis, I. M.; Itkis, M. G.; Knyazhev, G. N.; Kovalchuk, K. V.; Kvochkina, T. N.; Piasecki, E.; Rubchenya, V. A.; Sahiev, S. K.; Trzaska, W. H.; Vardaci, E.

    2016-12-01

    The mass-energy distributions and cross sections of proton-induced fission of 232Th have been measured at the proton energies of 7, 10, 13, 20, 40, and 55 MeV. Experiments were carried out at the proton beam of the K-130 cyclotron of the JYFL Accelerator Laboratory of the University of Jyväskylä and U-150m cyclotron of the Institute of Nuclear Physics, Ministry of Energy of the Republic of Kazakhstan. The yields of fission fragments in the mass range A = 60-170 a.m.u. have been measured up to the level of 10-4%. The three humped shape of the mass distribution up has been observed at higher proton energies. The contribution of the symmetric component grows up with increasing proton incident energy; although even at 55 MeV of proton energy the shoulders in the mass energy distribution clearly indicate the asymmetric fission peaks. Evolution of shell structure was observed in the fission fragment mass distributions even at high excitation energy.

  5. Proton induced fission of {sup 232}Th at intermediate energies

    SciTech Connect

    Gikal, K. B. Kozulin, E. M.; Bogachev, A. A.; Burtebaev, N. T.; Edomskiy, A. V.; Itkis, I. M.; Itkis, M. G.; Knyazhev, G. N.; Kovalchuk, K. V.; Kvochkina, T. N.; Piasecki, E.; Rubchenya, V. A.; Sahiev, S. K.; Trzaska, W. H.; Vardaci, E.

    2016-12-15

    The mass-energy distributions and cross sections of proton-induced fission of {sup 232}Th have been measured at the proton energies of 7, 10, 13, 20, 40, and 55 MeV. Experiments were carried out at the proton beam of the K-130 cyclotron of the JYFL Accelerator Laboratory of the University of Jyväskylä and U-150m cyclotron of the Institute of Nuclear Physics, Ministry of Energy of the Republic of Kazakhstan. The yields of fission fragments in the mass range A = 60–170 a.m.u. have been measured up to the level of 10−4%. The three humped shape of the mass distribution up has been observed at higher proton energies. The contribution of the symmetric component grows up with increasing proton incident energy; although even at 55 MeV of proton energy the shoulders in the mass energy distribution clearly indicate the asymmetric fission peaks. Evolution of shell structure was observed in the fission fragment mass distributions even at high excitation energy.

  6. Meridional circulation across the Antarctic Circumpolar Current serves as a double 231Pa and 230Th trap

    NASA Astrophysics Data System (ADS)

    Rutgers van der Loeff, Michiel; Venchiarutti, Celia; Stimac, Ingrid; van Ooijen, Jan; Huhn, Oliver; Rohardt, Gerd; Strass, Volker

    2016-12-01

    Upwelling of Circumpolar Deep Water in the Weddell Gyre and low scavenging rates south of the Antarctic Circumpolar Current (ACC) cause an accumulation of particle reactive nuclides in the Weddell Gyre. A ventilation/reversible scavenging model that successfully described the accumulation of 230Th in this area was tested with other particle reactive nuclides and failed to adequately describe the depth-distributions of 231Pa and 210Pb. We present here a modified model that includes a nutrient-like accumulation south of the Antarctic Polar Front in an upper meridional circulation cell, as well as transport to a deep circulation cell in the Weddell Gyre by scavenging and subsequent release at depth. The model also explains depletion of 231Pa and 230Th in Weddell Sea Bottom Water (WSBW) by ventilation of newly formed deep water on a timescale of 10 years, but this water mass is too dense to leave the Weddell Gyre. In order to quantify the processes responsible for the 231Pa- and 230Th-composition of newly formed Antarctic Bottom Water (AABW) we present a mass balance of 231Pa and 230Th in the Atlantic sector of the Southern Ocean based on new data from the GEOTRACES program. The ACC receives 6.0 ± 1.5 ×106 dpms-1 of 230Th from the Weddell Sea, similar in magnitude to the net input of 4.2 ± 3.0 ×106 dpms-1 from the north. For 231Pa, the relative contribution from the Weddell Sea is much smaller, only 0.3 ± 0.1 ×106, compared to 2.7 ± 1.4 ×106 dpms-1 from the north. Weddell Sea Deep Water (WSDW) leaving the Weddell Gyre northward to form AABW is exposed in the ACC to resuspended opal-rich sediments that act as efficient scavengers with a Th/Pa fractionation factor F ≤ 1. Hydrothermal inputs may provide additional removal with low F. Scavenging in the full meridional circulation across the opal-rich ACC thus acts as a double 231Pa and 230Th trap that preconditions newly formed AABW.

  7. Atlantic Meridional Overturning Circulation during Heinrich-Stadial 1 & 2 as seen by 231Pa/230Th

    NASA Astrophysics Data System (ADS)

    Antz, B.; Lippold, J. A.; Schulz, H.; Frank, N.; Mangini, A.

    2014-12-01

    Assessing the sensitivity of the Atlantic Meridional Overturning Circulation (AMOC) is a major challenge for paleoclimatology, because its strength and structure is a crucial element of the global heat- and carbon distribution towards the deep ocean. Here the focus is set on how excessive freshwater input through abrupt melting of continental ice sheets can affect its overturning vigour. Such forcing can be tested by investigating its behaviour during extreme iceberg discharge events into the open North Atlantic during the last glacial period, so called Heinrich-Events [Heinrich 1988; Hemming 2004]. The sedimentary activity ratio 231Pa/230Th has been increasingly used as a kinematic circulation proxy in the Atlantic Ocean over the past decade [Gherardi et al. 2009; McManus et al. 2004; Lippold et al. 2012]. Here we present 231Pa/230Th ratios from several Atlantic sediment cores across Heinrich Events 1 (~17 ka BP) and 2 (~24 ka BP). The comparison of the profiles demonstrates the potential pitfalls when interpreating a single 231Pa/230Th profile. E. g. core IODP 1313 (Mid Atlantic Ridge, 3412 m water depth) shows 231Pa/230Th between 0.04 and 0.06, which would indicate a vigorous circulation over the entire time period. On the other hand core GeoB 16202-2 (Brasilan coastal area, 2248 m water depth) has a profile similar to the well known data set of [McManus et al. 2004] (i.e. during Heinrich Stadials values close to the production ratio of ~0.093, lower values at Holocene and LGM). Such divergency can be explained by 231Pa/230Th dependence on water depth, latitude, water mass and water mass age [Luo et al. 2010; Lippold et al. 2011], but also on changes in bioproductivity especially the flux of biogenic opal [Anderson et al. 1983A; Bradtmiller et al. 2007; Chase et al. 2002]. To avoid misleading interpretations, the here shown data set is accompanied by measurements of biogenic opal contents to appraise possible influences on the proxies. We observe large

  8. Determination of 232Th in seawater by ICP-MS after preconcentration and separation using a chelating resin.

    PubMed

    Takata, Hyoe; Zheng, Jian; Tagami, Keiko; Aono, Tatsuo; Uchida, Shigeo

    2011-09-30

    This article describes an analytical method for the separation, preconcentration and determination of (232)Th in seawater samples at sub-ng/L levels using a NOBIAS CHELATE PA1 resin and a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). The resin showed excellent adsorption of (232)Th at a low pH of 2.4 ± 0.4 in a relatively small volume (200 mL) of seawater. (232)Th adsorbed on the resin was easily eluted using 5 mL of 0.8M HNO(3). An enrichment factor of 40 was achieved for (232)Th analysis. Ethylenediamine-tetraacetic acid disodium salt dehydrate (EDTA) was used to investigate the effect of (232)Th-binding organic ligand on the retention of (232)Th on the chelating resin. Results obtained using acidified samples (pH of 2.4 ± 0.4) showed EDTA had no significant effect on (232)Th recovery, indicating that at this low pH, (232)Th was dissociated from the (232)Th-binding organic ligand and quantitatively retained on the NOBIAS CHELATE PA1 resin. The developed analytical method was characterized by a separation and preconcentration taking approximately 4h and a low detection limit of 0.0038 ng/L for (232)Th, and was successfully applied to the determination of (232)Th in seawater samples collected from coastal areas, Japan. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Temporal evolution of (137)Cs, (237)Np, and (239+240)Pu and estimated vertical (239+240)Pu export in the northwestern Mediterranean Sea.

    PubMed

    Bressac, M; Levy, I; Chamizo, E; La Rosa, J J; Povinec, P P; Gastaud, J; Oregioni, B

    2017-10-01

    The evolution of (137)Cs, (237)Np and (239+240)Pu at the DYFAMED station (NW Mediterranean) is discussed in relation to physical processes, downward fluxes of particles, and changes in the main input sources. The data set presented in this study represents the first complete (237)Np vertical profiles (0.12-0.27μBqL(-1)), and constitutes a baseline measurement to assess future changes. A similar behavior of Cs and Np has been evidenced, confirming that Np behaves conservatively. While the (137)Cs decrease has been driven by its radioactive decay, the vertical distribution of (237)Np has not substantially changed over the last decade. In the absence of recent major inputs, a homogenization of their vertical distribution occurred, partly due to deep convection events that became more intense during the last decade. In contrast, (239+240)Pu surface levels in the NW Mediterranean waters have fallen in the past four decades by a factor of 5. This decrease in surface has been balanced by higher concentrations in the deep-water layers. A first estimate of the downward (239+240)Pu fluxes in the NW Mediterranean Sea is proposed over more than two decades. This estimation, based on the DYFAMED sediment trap time-series data and published (239+240)Pu flux measurements, suggests that sinking particles have accounted for 60-90% of the upper layer (0-200m) Pu inventory loss over the period 1989-2013. The upper layer residence time of Pu is estimated to be ~28years, twice as long as the residence time estimated for the whole western Mediterranean (~15years). This difference highlights the slow removal of Pu in the open waters of the NW Mediterranean and confirms that most of the Pu removal occurs along the coastal margin where sedimentation rates are high. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Measurement of the temporal characteristics of delayed neutrons from neutron induced fission of 237Np in the energy range from 14.2 to 18 MeV

    NASA Astrophysics Data System (ADS)

    Gremyachkin, Dmitrii E.; Piksaikin, Vladimir M.; Egorov, Andrey S.; Mitrofanov, Konstantin V.

    2017-09-01

    Analysis of existing database on the relative abundances of delayed neutrons and half-lives of their precursors measured for neutron induced fission of heavy nuclei in the energy range above 14 MeV shows that such data are not available for many nuclides, which are important for nuclear fuel cycle. In the present work for the first time the time dependence of delayed neutron activity for the neutron-induced fission of 237Np in the energy range above 14 MeV was obtained using T(d,n)4He.

  11. On the sequential separation and quantification of (237)Np, (241)Am, thorium, plutonium, and uranium isotopes in environmental and urine samples.

    PubMed

    Vasile, M; Jacobs, K; Bruggeman, M; Van Hoecke, K; Dobney, A; Verrezen, F

    2017-07-13

    The implementation of the one-pass-through separation technique using two stacked chromatography columns of TEVA - TRU resins for the separation of (237)Np, (241)Am, thorium, plutonium and uranium from environmental and urine samples was investigated. The sequential separation technique proved to be successful and gave similar results to those obtained when using individual separations. The analysis time was considerably improved. The amount of chemical waste was also reduced by 50% and the use of HClO4 was avoided. The technique of ICP-MS was also investigated as a complementary technique to alpha-spectrometry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. 230Th and 231Pa: Tracers for Deep Water Circulation and Particle Fluxes in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Valk, O.; Rutgers van der Loeff, M.; Puigcorbe Lacueva, V.; Paffrath, R.; Gdaniec, S.

    2016-02-01

    230Th and 231Pa data from the central Arctic Ocean is very limited. 230Th and 231Pa are produced at a constant rate in the water column by radioactive decay of Uranium isotopes (234U and 235U respectively) (e.g. Anderson et al., 1983). They are both particle reactive and are scavenged on settling particles. As 230Th is more particle reactive than 231Pa, their distribution in the water column and activity ratio give us information about particle fluxes and circulation patterns and -intensities (Henderson et al., 1999; Scholten et al., 2001). The Arctic Ocean is an almost landlocked ocean with limited connections to the Atlantic and Pacific and a high input of river water. About 10 % of the global river run-off is delivered to the Arctic Ocean. Due to climate change the Arctic Ocean will undergo dramatic changes in sea ice cover and supply of fresh water, while increasing coastal erosion will cause an increased input of terrestrial material (Peterson et al., 2002). This will influence the biogeochemical cycling and transport of carbon, nutrients and trace elements (IPCC, 2007). We expect that the distribution of 230Th and 231Pa will reflect changes in particle fluxes and shelf-basin exchange (Roy-Barman, 2009). We will present the first results of 230Th and 231Pa, in combination with on board measured particulate 234Th, collected during the 2015 Polarstern section (GEOTRACES section GN04 2015) through the Nansen, Amundsen, and Makarov Basins. Anderson, R. F., et al. (1983). EPSL 62: 7-23. Henderson, G. M., et al. (1999). DSR I 46: 1861-1893. IPCC, 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S. et al.]. Cambridge University Press. Peterson, B. J., et al. (2002). Science 298: 2171-2173. Roy-Barman, M. (2009). Biogeosciences 6: 3091-3107. Scholten, J. C., et al. (2001). DSR II 48: 2383-2408.

  13. Relationship between 237Np Mössbauer parameters and bond distances in nitrogen coordinated [NpO2(acac)2py

    NASA Astrophysics Data System (ADS)

    Kawasaki, Takeshi; Kitazawa, Takafumi; Nishimura, Tatsuru; Nakada, Masami; Saeki, Masakatsu

    2005-11-01

    We now report the 237Np Mössbauer spectra for [NpO2(acac)2py] I. The neptunium(VI) ion in I is coordinated by six oxygen atoms and the one nitrogen atom of pyridine. The isomer shift value obtained for I is -40 mm/s, which falls in the range for the Np(VI) oxidation state. The relationship between the isomer shift and Np O bond distance of the neptunyl group for oxygen coordination compounds is in good agreement with the reported structure of I. It is well known that the mean Np O bond distance of the neptunium compounds is shorter by 0.01 Å than that of analogous uranium compounds. The good agreement in the 237Np Mössbauer parameters and the Np O distance has indicated that the reported analogous [UO2(acac)2py] structure may have some inaccuracies. Therefore, we have re-determined the crystal structure of [UO2(acac)2py]. The U O bond distance we have obtained is reasonable.

  14. Concentrations of (226)Ra, (232)Th and (4)(0)K in industrial kaolinized granite.

    PubMed

    Todorović, Nataša; Hansman, Jan; Mrđa, Dušan; Nikolov, Jovana; Kardos, Richárd; Krmar, Miodrag

    2017-03-01

    Activity concentrations of (226)Ra, (232)Th and (4)(0)K in 120 kaolinized granite samples imported in Serbia from the Motajica mine, Bosnia and Herzegovina, were measured. The (226)Ra concentration ranged from 61 to 319 Bq kg(-1), the (232)Th from 44 to 272 Bq kg(-1), and the (4)(0)K from 590 to 1470 Bq kg(-1). The frequency distribution of (4)(0)K concentrations was near-Gaussian, where those of (226)Ra and (232)Th were right-skewed. In 6 samples, the gamma index, I, was higher than 2, which exceeds the exemption dose criterion (0.3 mSv y(-1)). The absorbed dose rate and annual effective doses for workers in the ceramic industries in Serbia who worked with kaolinized granite were below levels of concern.

  15. {sup 237}Np in Hemp-palm leaves of Bontenchiku for fishing gear used by the Fifth Fukuryu-Maru: 40 year after {open_quotes}Bravo{close_quotes}

    SciTech Connect

    Yamamoto, Masayoshi; Komura, Kazuhisa; Ueno, Kaoru

    1996-05-01

    The alpha radioactive components in the Hemp-palm leaves of Bontenchiku were determined with emphasis on the measurement of low-level {sup 237}Np by alpha-ray spectrometry after chemical separation. Bontenchiku is a kind of fishing gear for long-line fishing used by the Fifth Fukuryu-Maru (Lucky Dragon). This gear was exposed to fallout from the second thermonuclear test explosion (Bravo) at Bikini Atoll in March 1954. The {sup 237}Np content in the Bontenchiku sample was determined to be 11.5 {plus_minus}0.8 mBq g{sup {minus}1} with an activity ratio of {sup 237}Np: {sup 239,240}Pu and an atom ratio of {sup 237}Np: {sup 239}Pu estimated to be (2.2 {plus_minus}0.2) x 10{sup {minus}3} and 0.42 {plus_minus}0.04, respectively. The data showed the existence of a chain reaction of {sup 238}U and its ratio to be {sup 237}Np: {sup 239}Pu, as well as the presence of {sup 237}U at the time of fallout from Bravo event in March 1954. 12 refs., 5 figs., 1 tab.

  16. Preparation of Microvolume Anion-Exchange Cartridge for Inductively Coupled Plasma Mass Spectrometry-Based Determination of (237)Np Content in Spent Nuclear Fuel.

    PubMed

    Asai, Shiho; Hanzawa, Yukiko; Konda, Miki; Suzuki, Daisuke; Magara, Masaaki; Kimura, Takaumi; Ishihara, Ryo; Saito, Kyoichi; Yamada, Shinsuke; Hirota, Hideyuki

    2016-03-15

    Microvolume anion-exchange porous polymer disk-packed cartridges were prepared for Am/Np separation, which is required prior to the measurement of Neptunium-237 ((237)Np) with inductively coupled plasma mass spectrometry (ICPMS). Disks with a volume of 0.08 cm(3) were cut out from porous sheets having anion-exchange-group-containing polymer chains densely attached on the pore surface. Four different amine-based groups, N,N-dimethylaminoethyl methacrylate, trimethylammonium, diethylamine, and triethylenediamine (TEDA), were selected as the anion-exchange groups to be introduced into the porous sheets. The separation performances of Am/Np were evaluated using a standard solution of (243)Am, which had the same activity as its daughter nuclide (239)Np in secular equilibrium. (239)Np recovery of close to 100% with practically no contamination of (243)Am was achieved using the TEDA-introduced disk-packed cartridge. The time to elute (239)Np from the cartridge was approximately 40 s. The TEDA-introduced disk-packed cartridge was applied to the separation of Np from a spent nuclear fuel sample to confirm its separation performance. A known amount of (243)Am ((239)Np) was added to the spent nuclear fuel sample solution to monitor the chemical yield of Np. The chemical yield of Np calculated from a measured concentration of (239)Np was 90.4%. Am leakage in the Np-eluted solution was less than 1 ppt, corresponding to 0.001% of the original Am concentration in the sample. This indicates that no additional (239)Np was produced by the decay of the (243)Am remaining in the Np-eluted solution, thus providing a reliable chemical yield. U, which can cause a serious spectral interference involving the peak tail from the mass spectrum of (238)U, was thoroughly removed with the TEDA cartridge, providing interference-free measurement of (237)Np. The concentration of (237)Np obtained by ICPMS was 718 ± 12 ng/mg-U, which agrees well with the theoretically calculated value. Compared with

  17. Neutron-induced fission cross section of 237Np in the keV to MeV range at the CERN n_TOF facility

    NASA Astrophysics Data System (ADS)

    Diakaki, M.; Karadimos, D.; Vlastou, R.; Kokkoris, M.; Demetriou, P.; Skordis, E.; Tsinganis, A.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; David, S.; Dolfini, R.; Domingo-Pardo, C.; Dorochenko, A.; Dridi, W.; Duran, I.; Eleftheriadis, Ch.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fuji, K.; Furman, W.; Goncalves, I.; Gallino, R.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Ioannidis, K.; Isaev, S.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karamanis, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Kolokolov, D.; Konovalov, V.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Sedysheva, M.; Stamoulis, K.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Voss, F.; Wendler, H.; Wiescher, M.; Wisshak, K.; n TOF Collaboration

    2016-03-01

    The neutron-induced fission cross section of 237Np was experimentally determined at the high-resolution and high-intensity facility n_TOF, at CERN, in the energy range 100 keV to 9 MeV, using the 235U(n ,f ) and 238U(n ,f ) cross section standards below and above 2 MeV, respectively. A fast ionization chamber was used in order to detect the fission fragments from the reactions and the targets were characterized as far as their mass and homogeneity are concerned by means of α spectroscopy and Rutherford backscattering spectroscopy respectively. Theoretical calculations within the Hauser-Feshbach formalism have been performed, employing the empire code, and the model parameters were tuned in order to successfully reproduce the experimental fission cross-sectional data and simultaneously all the competing reaction channels.

  18. Transmutation of 129I and 237Np using spallation neutrons produced by 1.5, 3.7 and 7.4 GeV protons

    NASA Astrophysics Data System (ADS)

    Wan, J.-S.; Schmidt, Th.; Langrock, E.-J.; Vater, P.; Brandt, R.; Adam, J.; Bradnova, V.; Bamblevski, V. P.; Gelovani, L.; Gridnev, T. D.; Kalinnikov, V. G.; Krivopustov, M. I.; Kulakov, B. A.; Sosnin, A. N.; Perelygin, V. P.; Pronskikh, V. S.; Stegailov, V. I.; Tsoupko-Sitnikov, V. M.; Modolo, G.; Odoj, R.; Phlippen, P.-W.; Zamani-Valassiadou, M.; Adloff, J. C.; Debeauvais, M.; Hashemi-Nezhad, S. R.; Guo, S.-L.; Li, L.; Wang, Y.-L.; Dwivedi, K. K.; Zhuk, I. V.; Boulyga, S. F.; Lomonossova, E. M.; Kievitskaja, A. F.; Rakhno, I. L.; Chigrinov, S. E.; Wilson, W. B.

    2001-05-01

    Small samples of 129I and 237Np, two long-lived radwaste nuclides, were exposed to spallation neutron fluences from relatively small metal targets of lead and uranium, that were surrounded with a 6 cm thick paraffin moderator, and irradiated with 1.5, 3.7 and 7.4 GeV protons. The (n,γ) transmutation rates were determined for these nuclides. Conventional radiochemical La- and U-sensors and a variety of solid-state nuclear track detectors were irradiated simultaneously with secondary neutrons. Compared with results from calculations with well-known cascade codes (LAHET from Los Alamos and DCM/CEM from Dubna), the observed secondary neutron fluences are larger.

  19. Transmutation of 129I, 237Np, 238Pu, 239Pu, and 241Am using neutrons produced in target-blanket system 'Energy plus Transmutation' by relativistic protons

    NASA Astrophysics Data System (ADS)

    Adam, J.; Katovsky, K.; Balabekyan, A.; Kalinnikov, V. G.; Krivopustov, M. I.; Kumawat, H.; Solnyshkin, A. A.; Stegailov, V. I.; Stetsenko, S. G.; Tsoupko-Sitnikov, V. M.; Westmeier, W.

    2007-02-01

    Target-blanket facility `Energy + Transmutation' was irradiated by proton beam extracted from the Nuclotron Accelerator in Laboratory of High Energies of Joint Institute for Nuclear Research in Dubna, Russia. Neutrons generated by the spallation reactions of 0.7, 1.0, 1.5 and 2 GeV protons and lead target interact with subcritical uranium blanket. In the neutron field outside the blanket, radioactive iodine, neptunium, plutonium and americium samples were irradiated and transmutation reaction yields (residual nuclei production yields) have been determined using g-spectroscopy. Neutron field's energy distribution has also been studied using a set of threshold detectors. Results of transmutation studies of 129I, 237Np, 238Pu, 239Pu and 241Am are presented.

  20. Absolute and relative cross section measurements of 237Np(n,f) and 238U(n,f) at the National Physical Laboratory

    NASA Astrophysics Data System (ADS)

    Salvador-Castiñeira, Paula; Hambsch, Franz-Josef; Göök, Alf; Vidali, Marzio; Hawkes, Nigel P.; Roberts, Neil J.; Taylor, Graeme C.; Thomas, David J.

    2017-09-01

    Cross section measurements in the fast energy region are being demanded as one of the key ingredients for modelling Generation-IV nuclear power plants. However, in facilities where there are no time-of-flight possibilities or it is not convenient to use them, using the 235U(n,f) cross section as a benchmark would require a careful knowledge of the room scatter in the experimental area. In this paper we present measurements of two threshold reactions, 238U(n,f) and 237Np(n,f), that could become a standard between their fission threshold and 2.5 MeV, if the discrepancies shown in the evaluations and in some experimental data can be solved. The preliminary results are in agreement with the present ENDF/B-VII.1 evaluation.

  1. Dating ivory by determination of 14C, 90Sr and 228/232Th.

    PubMed

    Schmied, Stefanie A K; Brunnermeier, Matthias J; Schupfner, Robert; Wolfbeis, Otto S

    2012-09-10

    A method is described to determine the time of death of elephants. This is accomplished by analysis of the radionuclides 14C, 90Sr and 228/232Th in known samples of ivory, and in samples of unknown age. The reliability of this method is considerably increased by multi nuclide analysis.

  2. [The action of 232Th separately and in combination with heavy and alkaline metal salts on Tradescantia (clone 02)].

    PubMed

    Evseeva, T I; Geras'kin, S A

    2000-01-01

    The action of 232Th-nitrate in concentration 0.09, 0.18 and 0.36 mg/l (counting on 232Th ion) on water cultures of Tradescantia (clone 02) was investigated. It was found that all investigated concentrations of 232Th showed statistically significant genotoxic effect and increased level of morphological abnormal cells in the stamen hairs of Tradescantia in the absence of modifying action of other metal ions. Synergistic toxic interaction was found between the 232Th in concentration 0.18 mg/l and metal ions for all samples of thawed water. Synergistic genotoxic effect of the combined action of these factors was revealed only at the low total contents of ions of heavy and alkaline metals in thawed water samples. The observed synergistic effects of the combined action of 232Th and metal ions should be taken into account when controlling the radionuclide level in the environment.

  3. Study of contents of 226Ra, 232Th and 40K in fertilisers.

    PubMed

    Tahir, S N A; Alaamer, A S; Omer, R M

    2009-02-01

    In this study concentrations of naturally occurring radionuclides (226)Ra, (232)Th and (40)K were measured in the fertiliser samples in Pakistan using a high-resolution and high-purity germanium detector. Samples were collected from main fertiliser depots located in 10 big cities in the Punjab province. Gamma spectrometric analysis revealed that concentrations of (226)Ra, (232)Th and (40)K existed in the ranges from 232 to 511 Bq kg(-1), 21 to 58 Bq kg(-1) and 556 to 1302 Bq kg(-1) with average values of 386 +/- 92, 38 +/- 14 and 885 +/- 220 Bq kg(-1), respectively. Average values of the three natural radionuclides measured in this study were within the range of reported values from some of the other countries of the world. Correlations drawn between measured concentrations were not significant.

  4. [Cytogenetic effects of separate and combined action of 232Th and Cd nitrates on Allum cepa root meristem cells].

    PubMed

    Evseeva, T I; Geras'kin, S A; Khramova, E S

    2001-01-01

    Effects of separate and combined action of 232Th and Cd on Allium cepa root tip cells were investigated. It has been shown that cytogenetic effects of 232Th results mainly from its ability to induce genome damages. Cadmium in the examined concentration does not induce chromosomal vagrants, and this effect is not intensified by the combined action of 232Th and Cd (with 232Th). Cd induced increased aberrations of chromosome type frequency (1.5 times more than in control group), and fragment frequence, while mitotic index was significantly decreased. While taking into consideration the frequency of anaphase--telophase damages, and the number of aberrations per cell, the combined effects of 232Th and Cd may be considered as synergic. The aberration type ratio, frequencies of bridges and fragments, and also the level of proliferative activity of 232Th and Cd in the presence of both ions were similar with the corresponding parameters obtained when Cd acted alone. Possible mechanisms of formation of 232Th and Cd synergic effects are discussed.

  5. Ultra Sensitive Neutron Activation Measurements of {sup 232}Th in Copper

    SciTech Connect

    Clemenza, M.; Previtali, E.; Borio di Tigliole, A.; Salvini, A.

    2011-04-27

    Copper, thanks to its low content in radioactive contaminations, is a material widely used for shielding, holders and other objects close to the sensitive parts of the detectors in many experiments in rare event physics. This implies that tools able to reach sensitivity of the order of <10{sup -12} gram of contaminants per gram of copper are of crucial importance. A methodology based in Neutron Activation Analysis (NAA) has been developed to obtain an extremely high sensitivity in the analysis of {sup 232}Th in copper samples. A detection limit of 5x10{sup -13} g {sup 232}Th/g Cu has been achieved through the irradiation of 200 g of copper sample which subsequently was radio-chemically concentrated using nitric acid and then actinide resin from Eichrom Inc. Several elutions were performed with various inorganic acids to concentrate the {sup 232}Th activation product ({sup 233}Pa) from the copper matrix and to also eliminate the radioactive background induced by the neutron bombardment to reach higher sensitivity.

  6. 232Th, 233Pa, and 234U capture cross-section measurements in moderated neutron flux

    NASA Astrophysics Data System (ADS)

    Bringer, O.; Isnard, H.; AlMahamid, I.; Chartier, F.; Letourneau, A.

    2008-07-01

    The Th-U cycle was studied through the evolution of a 100 μg 232Th sample irradiated in a moderated neutron flux of 8.010 14 n/cm 2/s, intensity close to that of a thermal molten salt reactor. After 43 days of irradiation and 6 months of cooling, a precise mass spectrometric analysis, using both TIMS and MC-ICP-MS techniques, was performed, according to a rigorous methodology. The measured thorium and uranium isotopic ratios in the final irradiated sample were then compared with integral simulations based on evaluated data; an overall good agreement was seen. Four important thermal neutron-capture cross-sections were also extracted from the measurements, 232Th (7.34±0.21 b), 233Pa (38.34±1.78 b), 234U (106.12±3.34 b), and 235U (98.15±11.24 b). Our 232Th and 235U results confirmed existing values whereas the cross-sections of 233Pa and 234U (both key parameters) have been redefined.

  7. Feasibility of 99Mo production by proton-induced fission of 232Th

    NASA Astrophysics Data System (ADS)

    Abbas, Kamel; Holzwarth, Uwe; Simonelli, Federica; Kozempel, Jan; Cydzik, Izabela; Bulgheroni, Antonio; Cotogno, Giulio; Apostolidis, Christos; Bruchertseifer, Frank; Morgenstern, Alfred

    2012-05-01

    The current global crisis in supply of the medical isotope generator 99Mo/99mTc has triggered much research into alternative non-reactor based production methods for 99Mo including innovative radionuclide production techniques using ion accelerators. A novel method is presented here that has thus far not been considered: 232Th is used as target material to produce carrier-free 99Mo for 99Mo/99mTc generators by proton-induced fission (232Th (p, f) 99Mo). The thick target yields of 99Mo are estimated as 3.6 MBq/μA·h and 21 MBq/μA·h for proton energies of 22 MeV and 40 MeV, respectively, energies that are available from many cyclotrons. With respect to 99Mo reactor based methods using uranium targets, the presented concept using 232Th does not pose proliferation concerns, transport of highly radioactive target materials can be reduced and unused cyclotron capacities could be exploited. Radiochemical target processing could be based on existing technologies of extraction of 99Mo from reactor irradiated 235U. The presented method could be used for co-production of other radioisotopes of medical interest such as 131I.

  8. Structural investigation of Na3NpO4 and Na3PuO4 using X-ray diffraction and (237)Np Mössbauer spectroscopy.

    PubMed

    Smith, A L; Raison, P E; Hen, A; Bykov, D; Colineau, E; Sanchez, J-P; Konings, R J M; Cheetham, A K

    2015-11-14

    α-Na3NpO4 and α-Na3PuO4 exhibit an orthorhombic structure (Z = 8), in space group Fmmm, with lattice parameters a = 13.352(2) Å, b = 9.629(2) Å, and c = 6.673(2) Å for the neptunium compound, and a = 13.302(2) Å, b = 9.634(2) Å, and c = 6.651(2) Å for the plutonium analogue. The corresponding structure has been solved ab initio as no structural analogue could be found in the literature. The pentavalent state of neptunium has moreover been confirmed by (237)Np Mössbauer spectroscopy, and the local structural properties inferred from the X-ray Rietveld refinement have been related to the fitted quadrupole coupling constant and asymmetry parameters. The existence of a low temperature metastable m phase of Na3NpO4 and Na3PuO4, of the NaCl type, has also been suggested.

  9. Dissolved and Particulate 230Th - 232Th systematics in the Central Equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Lopez, G. I.; Marcantonio, F.

    2013-12-01

    To complement our work in the eastern Equatorial Pacific, we have measured total and dissolved 230Th and 232Th in the central Equatorial Pacific at two sites, one at 8°N and the other at the equator (ML1208-03CTD; 00° 13.166' S, 155° 57.668' W and ML1208-12CTD; 8° 19.989' N, 159° 18.000' W). The two seawater casts were collected in May 2012 during an NSF-funded "Line Islands" cruise to test for the extent of advection or diffusion of dissolved 230Th from the oligotrophic North Pacific gyre (low particle flux) to the more productive equatorial region (high particle flux). Our thorium results are similar to previous data published for the western and central North Pacific Ocean. Dissolved 230Th concentrations range from 1.1 fg/kg at 100 m to 30.8 fg/kg at 4400 m, while dissolved 232Th concentrations span from 8.1 pg/kg at 900 m to 19.7 pg/kg at 4400 m. The pattern of the dissolved 230Th profile at 8°N is essentially linear from the surface to 2000 m. From 2000 m to 3000 m, the dissolved 230Th concentrations are constant, and then from 3000 m to the bottom, the profile is linear again. At the same site, the particulate fraction of the total seawater 230Th increases exponentially from about 0% at the surface to 38% at 4400 m. From 0 to 3000 m at 8°N, dissolved 232Th concentrations display a relatively constant pattern (variability of about 20%). From 3000 m to 4400 m, dissolved 232Th contents are more variable, but generally increase toward greater depths. The proportion of 232Th in the particulate fraction of the total seawater sample increases exponentially with depth to a value of 58% in the bottommost sample. We will present additional data from the equator and assess the particulate dynamics that control the distribution of thorium isotopes in central equatorial Pacific seawater.

  10. {sup 226}Ra and {sup 231}Pa systematics of axial MORB, crustal residence ages, and magma chamber characteristics at 9--10{degree}N East Pacific Rise

    SciTech Connect

    Goldstein, S.J.; Murrell, M.T.; Perfit, M.R.; Batiza, R.; Fornari, D.J.

    1994-06-01

    Mass spectrometric measurements of {sup 30}Th-22{sup 226}Ra and {sup 235}-U{sup 231}Pa disequilibria for axial basalts are used to determine crustal residence ages for MORB magma and investigate the temporal and spatial characteristics of axial magma chambers (AMC) at 9--10{degrees}N East Pacific Rise (EPR). Relative crustal residence ages can be calculated from variations in {sup 226}Ra/{sup 230}Th and {sup 231}Pa/{sup 235}U activity ratios for axial lavas, if (1) mantle sources and melting are uniform, and mantle transfer times are constant or rapid for axial N-MORB, and (2) {sup 231}Pa/{sup 235}U and {sup 226}Ra/{sup 230}Th in the melt are unaffected by shallow level fractional crystallization. Uniform Th, Sr, and Nd isotopic systematics and incompatible element ratios for N-MORB along the 9--10{degrees}N segment indicate that mantle sources and transfer times are similar. In addition, estimated bulk solid/melt partition coefficients for U, Th, and Pa are small, hence effects of fractional crystallization on {sup 231}Pa/{sup 235}U ratios for the melt are expected to be negligible. However, fractional crystallization of plagioclase in the AMC would lower {sup 226}Ra/{sup 230}Th ratios in the melt and produce a positive bias in {sup 226}Ra crustal residence ages for fractionated lavas.

  11. [Mechanisms of 232Th effects on Chlorella vulgaris Beljer and modifications of it's toxic effect with caffeine and buthionine sulfoximine].

    PubMed

    Evseeva, T I; Maĭstrenko, T A; Geras'kin, S A; Belykh, E S

    2006-01-01

    232Th effects and its modifications with caffeine and D, L-buthionine-(S, R)-sulphoximine in Chlorella vulgaris Beijer cells was studied with use an optical density measure after 24 hours growth. Was shown relationship between concentration and toxic effect that is nonlinear and characterized with three parts different in induced damages level. In the first concentration range (0.001-1.551 micromol/l) chlorella growth parameters don't significantly differ from control ones. In the second one (1.724-3.017 micromol/1) statistically significant increase of optical density is but the effect does not dependent on 232Th concentration. The 232Th concentration (>3.448 micromol/l) increase the monotonous decrease in optical density was observed. The main role in 232Th toxic effect decrease make processes of DNA reparation, but not free radical scavenging with glutathione.

  12. Measurement of attogram quantities of 231Pa in dissolved and particulate fractions of seawater by isotope dilution thermal ionization mass spectroscopy.

    PubMed

    Shen, Chuan-Chou; Cheng, Hai; Edwards, R Lawrence; Moran, S Bradley; Edmonds, Henrietta N; Hoff, John A; Thomas, Rebecca B

    2003-03-01

    A technique has been developed to quantify ultratrace 231Pa (50-2000 ag; 1 ag = 10(-18) g) concentrations in seawater using isotope-dilution thermal ionization mass spectrometry (TIMS). The method is a modification of a process developed by Pickett et al. (Pickett, D. A.; Murrell, M. T.; Williams, R. W. Anal. Chem. 1994, 66, 1044-1049) and extends the technique to very low levels of protactinium. The procedural blank is 16 +/- 15 ag (2sigma), and the ionization efficiency (ions generated/atom loaded) approaches 0.5%. Measurement time is <1 h. The amount of 231Pa needed to produce 231Pa data with an uncertainty of +/-4-12% is 100-1000 ag (approximately 3 x 10(5) to 3 x 10(6) atoms). Replicate measurements made on known standards and seawater samples demonstrate that the analytical precision approximates that expected from counting statistics and that, based on detection limits of 38 and 49 ag, protactinium can be detected in a minimum sample size of surface seawater of approximately 2 L for suspended particulate matter and <0.1 L for filtered (<0.4 microm) seawater, respectively. The concentration of 231Pa (tens of attograms per liter) can be determined with an uncertainty of +/-5-10% (2sigma) for suspended particulate matter filtered from 5 to 10 L of seawater. For the dissolved fraction, 0.5-1 L of seawater yields 231Pa measurements with a precision of 1-10%. Sample size requirements are orders of magnitude less than traditional decay-counting techniques and significantly less than previously reported ICP-MS techniques. Our technique can also be applied to other environmental samples, including cave waters, rivers, and igneous rocks.

  13. 230Th and 231Pa on GEOTRACES GA03, the U.S. GEOTRACES North Atlantic transect, and implications for modern and paleoceanographic chemical fluxes

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher T.; Anderson, Robert F.; Fleisher, Martin Q.; Huang, Kuo-Fang; Robinson, Laura F.; Lu, Yanbin; Cheng, Hai; Edwards, R. Lawrence; Moran, S. Bradley

    2015-06-01

    The long-lived uranium decay products 230Th and 231Pa are widely used as quantitative tracers of adsorption to sinking particles (scavenging) in the ocean by exploiting the principles of radioactive disequilibria. Because of their preservation in the Pleistocene sediment record and through largely untested assumptions about their chemical behavior in the water column, the two radionuclides have also been used as proxies for a variety of chemical fluxes in the past ocean. This includes the vertical flux of particulate matter to the seafloor, the lateral flux of insoluble elements to continental margins (boundary scavenging), and the southward flux of water out of the deep North Atlantic. In a section of unprecedented vertical and zonal resolution, the distributions of 230Th and 231Pa across the North Atlantic shed light on the marine cycling of these radionuclides and further inform their use as tracers of chemical flux. Enhanced scavenging intensities are observed in benthic layers of resuspended sediments on the eastern and western margins and in a hydrothermal plume emanating from the Mid-Atlantic Ridge. Boundary scavenging is clearly expressed in the water column along a transect between Mauritania and Cape Verde which is used to quantify a bias in sediment fluxes calculated using 230Th-normalization and to demonstrate enhanced 231Pa removal from the deep North Atlantic by this mechanism. The influence of deep ocean ventilation that leads to the southward export of 231Pa is apparent. The 231Pa/230Th ratio, however, predominantly reflects spatial variability in scavenging intensity, complicating its applicability as a proxy for the Atlantic meridional overturning circulation.

  14. Theoretical analyses of (n,xn) reactions on sup 235 U, sup 238 U, sup 237 Np, and sup 239 Pu for ENDF/B-VI

    SciTech Connect

    Young, P.G.; Arthur, E.D.

    1991-01-01

    Theoretical analyses were performed of neutron-induced reactions on {sup 235}U, {sup 238}U, {sup 237}Np, and {sup 239}Pu between 0.01 and 20 MeV in order to calculate neutron emission cross sections and spectra for ENDF/B-VI evaluations. Coupled-channel optical model potentials were obtained for each target nucleus by fitting total, elastic, and inelastic scattering cross section data, as well as low-energy average resonance data. The resulting deformed optical model potentials were used to calculate direct (n,n{prime}) cross sections and transmission coefficients for use in Hauser-Feshbach statistical theory analyses. A fission model with multiple barrier representation, width fluctuation corrections, and preequilibrium corrections were included in the analyses. Direct cross sections for higher-lying vibrational states were calculated using DWBA theory, normalized using B(E{ell}) values determined from (d,d{prime}) and Coulomb excitation data, where available, and from systematics otherwise. Initial fission barrier parameters and transition state density enhancements appropriate to the compound systems involved were obtained from previous analyses, especially fits to charged-particle fission probability data. The parameters for the fission model were adjusted for each target system to obtain optimum agreement with direct (n,f) cross section measurements, taking account of the various multichance fission channels, that is, the different compound systems involved. The results from these analyses were used to calculate most of the neutron (n,n), (n,n{prime}), and (n,xn) cross section data in the ENDF/B/VI evaluations for the above nuclei, and all of the energy-angle correlated spectra. The deformed optical model and fission model parameterizations are described. Comparisons are given between the results of these analyses and the previous ENDF/B-V evaluations as well as with the available experimental data. 14 refs., 3 figs., 1 tab.

  15. Measurement of the {sup 237}Np(n,{gamma}) cross section from 20 meV to 500 keV with a high efficiency, highly segmented 4{pi} BaF{sub 2} detector

    SciTech Connect

    Esch, E.-I.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Glover, S. E.; Haight, R. C.; Jandel, M.; Kawano, T.; Mertz, A.; O'Donnell, J. M.; Rundberg, R. S.; Schwantes, J. M.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Reifarth, R.; Greife, U.; Hatarik, A. M.; Hatarik, R.

    2008-03-15

    The {sup 237}Np(n,{gamma}){sup 238}Np cross section has been measured in the neutron energy range from 20 meV to 500 keV using the DANCE array at the Los Alamos National Laboratory. This new facility allows experiments with submilligram samples and is therefore well suited to investigate isotopes with half-lives as low as a few hundred days. In this benchmark measurement, only 0.42 mg of {sup 237}Np was sufficient to determine differential cross sections relative to the well-known resonance at 0.5 eV. The thermal cross section was measured to {sigma}{sub 2200m/s}=177{+-}5 barn, {sigma}{sub kT=25.3meV}=167{+-}4 barn and the resonance integral to RI=693{+-}6 barn.

  16. Studies of positron electron pair production in {sup 238}U + {sup 232}Th

    SciTech Connect

    Ahmad, I.; Back, B.B.; Betts, R.R.

    1995-08-01

    Following the non-observation of sharp sum-energy lines in our earlier {sup 238}U + {sup 181}Ta measurements, it was decided to pursue measurements of the {sup 238}U + {sup 232}Th system which, in the previously published work, showed the most striking evidence for near-equal-energy back-to-back pairs leading to sharp sum-energy lines. Following the refurbishing of the APEX silicon arrays and extensive tests of the rotating target wheel assembly, a major positron run took place in November 1994. Rolled 1-mg/cm{sub 2} {sup 232}Th targets were bombarded with 5.95-MeV/u {sup 238}U. The target rotation allowed up to 2 pnA of beam to be used without serious deterioration of the targets. Over 300,000 pairs were accumulated, representing an order-of-magnitude improvement in statistics over the previously published results. Preliminary analysis shows no evidence for the sharp lines at a cross section level orders of magnitude below those previously reported. The analysis of these data is currently being completed in preparation for publication.

  17. Determination of 232Th in urine by ICP-MS for individual monitoring purposes.

    PubMed

    Baglan, N; Cossonnet, C; Ritt, J

    2001-07-01

    Thorium is naturally occurring in various ores used for industrial purposes and has numerous applications. This paper sets out to investigate urine analysis as a suitable monitoring approach for workers potentially exposed to thorium. Due to its biokinetic behavior and its low solubility, urinary concentrations are generally very low, requiring therefore high sensitivity analytical methods. An analytical procedure has been developed for detecting 232Th concentrations of below 1 mBq L(-1) quickly and easily. Due to the long half-life (1.41 x 10(10) y) of 232Th, the potential of a procedure based on urine sample dilution and ICP-MS (inductively coupled plasma-mass spectrometry) measurement was investigated first. Two dilution factors were chosen: 100, which is more suitable for long-term measurement trials, and 20, which increases sensitivity. It has been shown that a 100-fold dilution can be used to measure concentrations of below 1 mBq L(-1), whereas a 20-fold one can be used to reach concentrations of below 0.06 mBq L(-1). Then, on the basis of the limitation of the procedure based on urine dilution, the suitable field of application for the different procedures (100-fold and 20-fold dilution and also a chemical purification followed by an ICP-MS measurement) was determined in relation to monitoring objectives.

  18. The low-energy dipole structure of 232Th , 236U and 238U actinide nuclei

    NASA Astrophysics Data System (ADS)

    Kuliev, A. A.; Guliyev, E.; Ertugral, F.; Özkan, S.

    2010-03-01

    In this study, ensuremath I^{π} = 1+ and ensuremath I^{π} = 1- dipole mode excitations are systematically investigated within the rotational and translational + Galilean invariant quasiparticle random-phase approximation for 232Th , 236U , and 238U actinide nuclei. It is shown that the investigated nuclei reach a B( M1) strength structure, which corresponds to the scissors mode. The calculated mean excitation energies as well as the summed B( M1) value of the scissors mode excitations are consistent with the available experimental data. The results of calculations indicate large differences to the rare-earth nuclei as is the case for the experiment: a doubling of the observed dipole strengths and a shift of the energy centroid to the lower energies by about 800keV. The calculations indicate the presence of a few prominent negative-parity ensuremath K^{π} = 1- states in the 2.0-4.0MeV energy interval. The occurrence of the negative-parity dipole states with the rather high B( E1) value less than 4MeV shows the necessity of explicit parity measurements for the correct determination of the scissors mode strength in 232Th , 236U , and 238U isotopes.

  19. 232Th-228Ra-228Th Recording of Estuarine and Coastal Sedimentological Events

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, C.; Ghaleb, B.; Ruiz-Fernandez, A.

    2011-12-01

    Climatic events (e.g., storminess, floods) and river/coastal management activities (e.g., dredging) may result in the removal and re-suspension of contaminated sediments in shallow coastal areas and estuaries, thus leading to long-term contamination of such environments. Short-lived daughter isotopes of 232Th (228Ra-228Th) in sediments may then provide some quantitative assessment of the amount of material removed/re-deposited as well as some indications on the chronology of causal events. Examples from the Gulf of St. Lawrence (GSL) and the Pacific coastal rea of Mexico (PcM) are used to illustrate such isotopic responses to natural or anthropogenic disturbances. In the GSL relatively steady accumulation processes are usually observed, although sedimentary sequences show variable benthic mixing patterns over a large array of sedimentation rates (from mm/a to cm/a). In undisturbed sequences, 232Th-daughter isotopes in particulate matter show strong disequilibria due i) to 228Ra-diffusion/228Th adsorption in source-soils and during particulate transport, ii) 228Ra-behavior at the water column/sea-floor interface. Core-top sediments thus depict a strong excess in 228Th vs. 232Th. Below, a fast return (within ~ 10 a) of 228Th to equilibrium with its parent 228Ra leads to a 228Th deficit vs 232Th, in response to 228Ra-losses and diffusion towards the water column. Deeper, a return to full equilibrium conditions is observed (~ 30 a), but for "non-local mixing" events. Few disturbances are observed in the area. They include nearly cyclic pulses in 210Pb at the head of the Laurentian Trough, which we attribute to dredging operations of the St. Lawrence Sea-Way, and in the sealing of Hg-contaminated sediments in the Saguenay Fjord, by flood layers. Comparatively most sequences cored in estuarine settings of the PcM illustrate more critical situations with respect to the re-suspension of sediments, which are often contaminated due to land management and industrial practices

  20. Transfer factor of 226Ra, 232Th and 40K from soil to Alpinia Galangal plant grown in northern Thailand

    NASA Astrophysics Data System (ADS)

    Kritsananuwat, R.; Chanyotha, S.; Kranrod, C.; Pengvanich, P.

    2017-06-01

    This paper reports the activity concentration of three natural radionuclides, 226Ra, 232Th and 40K, found in Alpinia Galangal plants which are widely used in various Asian cuisines and traditional medicine. The galangal plants and their relevant soils were collected from four provinces in the north of Thailand under natural field conditions. The activity concentration of radionuclides was determined using gamma-ray spectrometry. Soil-to-plant transfer factors (TFs) for 226Ra, 232Th and 40K were investigated in rhizome and aerial parts of the galangal plants. The activity concentration in the soils ranged from 22 to 88 Bq kg-1 for 226Ra, 27 to 157 Bq kg-1 for 232Th and 58 to 1157 Bq kg-1 for 40K. In Alpinia Galangal, the concentration ranged from < 0.2 to 2.0 Bq kg-1 for 226Ra, < 0.1 to 2.9 Bq kg-1 for 232Th and 205 to 2247 Bq kg-1 for 40K. The TF ranged from < 0.002 to 0.073 for 226Ra, < 0.001 to 0.061 for 232Th and 0.26 to 7.9 for 40K. The TFs in the aerial parts were higher than those for the rhizomes. The obtained values can be considered as a baseline data for activity concentrations of natural radionuclides and their TFs in Thailand for future environmental radiation monitoring. The Annual effective ingestion dose due to ingestion of 226Ra, 232Th and 40K in galangals is significantly below the worldwide value reported by UNSCEAR 2000.

  1. 232Th(n,γ)233Th Thermal Reaction Cross-Section Measurement

    NASA Astrophysics Data System (ADS)

    Maidana, Nora L.; Vanin, Vito R.; Castro, Ruy M.; Pascholati, Paulo R.; Helene, Otaviano; Dias, Mauro S.; Koskinas, Marina F.

    2005-05-01

    The 232Th(n,γ)233Th thermal neutron-capture reaction cross section was measured using targets of ˜ 1.5 mg of high-purity metallic thorium irradiated in the IPEN IEA-R1m 5 MW pool research reactor. The 197Au(n,γ)198Au reaction was used to monitor the thermal and epithermal neutron fluxes in the irradiation position, which was found using the Westcott formalism. The residual gamma-ray activity was followed with an HPGe detector. The detector efficiency curve was fitted by the least-squares method applying covariance analysis to all uncertainties involved. The experimental result is σ0 =7.20±0.20 b, in agreement with previous published values.

  2. 232Th(n,{gamma})233Th Thermal Reaction Cross-Section Measurement

    SciTech Connect

    Maidana, Nora L.; Vanin, Vito R.; Pascholati, Paulo R.; Helene, Otaviano; Castro, Ruy M.; Dias, Mauro S.; Koskinas, Marina F.

    2005-05-24

    The 232Th(n,{gamma})233Th thermal neutron-capture reaction cross section was measured using targets of {approx} 1.5 mg of high-purity metallic thorium irradiated in the IPEN IEA-R1m 5 MW pool research reactor. The 197Au(n,{gamma})198Au reaction was used to monitor the thermal and epithermal neutron fluxes in the irradiation position, which was found using the Westcott formalism. The residual gamma-ray activity was followed with an HPGe detector. The detector efficiency curve was fitted by the least-squares method applying covariance analysis to all uncertainties involved. The experimental result is {sigma}0 =7.20{+-}0.20 b, in agreement with previous published values.

  3. Systematics of the mean energy and the mean multiplicity of prompt neutrons originating from {sup 232}Th fission

    SciTech Connect

    Svirin, M. I.

    2012-12-15

    The cross section for the neutron-induced fission of {sup 232}Th target nuclei, {sigma}{sub f} (E{sub n}), was described within statistical theory. The spectra of the mean multiplicity, v-bar (E{sub n}), and the mean energy, E-bar(E{sub n}), of secondary neutrons accompanying {sup 232}Th fission induced by neutrons of energy extending up to E{sub n} = 20 MeV were analyzed on the basis of the chance structure of the cross section.

  4. Size-fractionated thorium isotopes (228Th, 230Th, 232Th) in surface waters in the Jiulong River estuary, China.

    PubMed

    Zhang, Lei; Chen, Min; Yang, Weifeng; Xing, Na; Li, Yanping; Qiu, Yusheng; Huang, Yipu

    2005-01-01

    Thorium isotopes (228Th, 230Th, 232Th and 234Th) are useful tracers for studying particle dynamics and trace element scavenging in marine environments. In this study, surface waters were collected along a salinity gradient from the Jiulong River estuary, China, for determination of activity concentrations of 228Th, 230Th and 232Th in different size fractions, namely, the >53 microm, 10-53 microm, 2-10 microm, 0.4-2 microm, 10 kDa-0.4 microm and the <10 kDa fractions. Our results indicated that the activity concentrations of 228Th, 230Th and 232Th in the Jiulong River estuarine waters were significantly higher than most of the previously reported values in coastal and oceanic seawaters, suggesting a higher lithogenic U and Th contribution from the Jiulong River Basin. When normalized to the particulate mass concentration, the activity concentrations of the three thorium isotopes decreased with increasing particle size, demonstrating the important role of surface areas of particles in controlling the scavenging of thorium from the water column. The partitioning of three thorium isotopes showed a common characteristic, i.e., the >53 microm fraction had the least share (0-1%), while the 10-53 microm fraction had the largest share of Th isotopes. The average value of the 230Th/232Th activity ratio (230Th/232Th)(A.R.) increased from 0.8 in the >53 microm fraction to 3.7 in the 10 kDa-0.4 microm fraction, indicating that the radiogenic Th isotopes are preferentially scavenged by the small size particles. (230Th/232Th)(A.R.) in the <10 kDa and 10 kDa-0.4 microm fractions were similar, however, suggesting a similar chemical composition and/or equilibrium partitioning between the low molecular weight and colloidal Th. It was very interesting to note that the geochemical behaviors of the three Th isotopes were different from each other. Dissolved 228Th had the highest concentration in the mid-salinity region, showing a non-conservative behavior with additional input. In

  5. Investigating the use of 232Th/230Th as a dust proxy using co-located seawater and sediment samples from the low-latitude North Atlantic

    NASA Astrophysics Data System (ADS)

    Rowland, George H.; Ng, Hong Chin; Robinson, Laura F.; McManus, Jerry F.; Mohamed, Kais J.; McGee, David

    2017-10-01

    The thorium isotope ratio 232Th/230Th can be measured in seawater and sediment samples, and has been used as a proxy to reconstruct lithogenic fluxes to the oceans for the modern day and the Pleistocene. There has not yet been a systematic study testing the proxy using the 232Th/230Th ratio in seawater and the ratio recorded in the underlying sediment. In this study we use co-located core-top sediments and seawater samples from five seamount sites spanning the tropical North Atlantic to investigate the link between seawater and sediment 232Th/230Th ratios across a range of water depths. Our results indicate that a broad correlation exists between seawater and sedimentary 232Th/230Th ratios. Both seawater and sedimentary 232Th/230Th ratios record a signal consistent with decreasing lithogenic input east to west, from Africa to South America. However, calculated 232Th fluxes for the core-top sediment samples indicate a strong dependence on depth, with up to a factor of ∼4 difference from shallow (<600 m) to deep sites (>2900 m). This depth dependence is likely caused by either a deficit of 230Th burial at depth compared to the production in the overlying water column, through addition of 232Th, or by a combination of the two. By comparing seawater and sedimentary 232Th/230Th ratios we derive an apparent fractional solubility of 232Th of 29 ± 3%, in reasonable agreement with the upper end of existing estimates.

  6. Sorption of {sup 60}Co, {sup 85}Sr, {sup 137}Cs, {sup 237}Np and {sup 241}Am on soil under coexistence of humic acid: Effects of molecular size of humic acid

    SciTech Connect

    Tanaka, Tadao; Senoo, Muneaki

    1995-12-31

    Sorption experiments have been performed by a batch method, to study the effects of humic acid of different molecular size on the complexing stability with {sup 60}Co, {sup 85}Sr, {sup 137}Cs, {sup 237}Np and {sup 241}Am, and on the sorption behavior of these radionuclides on a sandy soil. Equilibrium constants K in the sorption of {sup 137}Cs and {sup 237}Np onto the soil were not changed at different concentrations of humic acid since {sup 137}Cs and {sup 237}Np do not interact with humic acid, while those of {sup 60}Co and {sup 241}Am decreased with increasing humic acid concentration due to forming humic complexes. However, the K of {sup 85}Sr was not changed at different humic acid concentrations, despite {sup 85}Sr interacts with humic acid. This contradiction was probably caused from that a main binding of {sup 85}Sr with humic acid is not based on coordination bond but electrostatic force, due to relatively high concentration of non-radioactive strontium. The theoretical sorption model taking account of the interaction of {sup 60}Co and {sup 241}Am with humic acid could well reproduce the values of K for each radionuclide at different concentrations of humic acid. Concentration profiles of the radionuclides in each size fraction of the solution before and after the sorption experiments were examined by ultrafiltration technique. The reduction of concentration of {sup 60}Co in the fraction less than 300,000 of cutoff molecular weight (MW) and that of concentration of {sup 241}Am in the fraction larger than 100,000MW, respectively, by the sorption onto the soil decreased with increasing humic acid concentration. This decrease resulted in the decrease in the K of {sup 60}Co and {sup 241}Am with increasing humic acid concentration.

  7. High precision {sup 230}Th and {sup 232}Th in the Norwegian Sea and Denmark by thermal ionization mass spectrometry

    SciTech Connect

    Moran, S.B.; Hoff, J.A.; Edwards, R.L.

    1995-10-01

    Seawater samples (1-2 liters) were collected from the Norwegian Sea and Denmark Strait and analyzed for {sup 230}Th and {sup 232}Th using highly sensitive thermal ionization mass spectrometry (TIMS). Depth profiles of dissolved {sup 230}Th and {sup 232}Th are characterized by surface water minima (<1 fg/kg, <5 pg/kg), subsurface maxima (12 fg/kg, 134 pg/kg), and intermediate concentrations that progressively decrease toward the bottom ({approximately}5 fg/kg, {approximately}17 pg/kg), respectively. The lack of an increase in {sup 230}Th with depth is suggested to result from the short ventilation age of Norwegian Sea Deep Water combined with enhanced scavenging near the basin margins. The {sup 230}Th maximum is attributed to advection of high {sup 230}Th in the Arctic Intermediate Water, whereas the {sup 232}Th maximum may he related to a particulate source. The low dissolved {sup 230}Th and {sup 232}Th concentrations observed in the NADW formation regions implies a minor advective export of these long-lived Th tracers to the North Atlantic. 24 refs., 1 fig., 1 tab.

  8. Measurement of fission products yields in the quasi-mono-energetic neutron-induced fission of 232Th

    NASA Astrophysics Data System (ADS)

    Naik, H.; Mukherji, Sadhana; Suryanarayana, S. V.; Jagadeesan, K. C.; Thakare, S. V.; Sharma, S. C.

    2016-08-01

    The cumulative yields of various fission products in the 232Th(n, f) reaction at average neutron energies of 5.42, 7.75, 9.35 and 12.53 MeV have been determined by using an off-line γ-ray spectrometric technique. The neutron beam was produced from the 7Li(p, n) reaction by using the proton energies of 7.8, 12, 16 and 20 MeV. The mass chain yields were obtained from the cumulative fission yields by using the charge distribution correction of medium energy fission. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect. On the other hand, the higher yield around mass number 133-134 and 143-144 as well as their complementary products were explained based on the standard I and standard II asymmetric mode of fission. From the mass yield data, the average value of light mass (), heavy mass (), the average number of neutrons (< ν >) and the peak-to-valley (P / V) ratios at different neutron energies of present work and literature data were obtained in the 232Th(n, f) reaction. The different parameters of the mass yield distribution in the 232Th(n, f) reaction were compared with the similar data in the 232Th(γ, f) reaction at comparable excitation energy and a surprising difference was observed.

  9. sup 238 U- and sup 232 Th-series chronology of phonolite fractionation at Mount Erebus, Antarctica

    SciTech Connect

    Reagan, M.K. ); Volpe, A.M. ); Cashman, K.V. )

    1992-03-01

    Uranium, thorium, radium, and barium abundances and {sup 234}U/{sup 238}U and {sup 230}Th/{sup 232}Th isotopic ratios determined by thermal ionization mass spectrometry and ({sup 228}Th)/({sup 232}Th) activity ratios determined by alpha spectrometry are used to date anorthoclase growth and infer magma chamber residence times of phonolites erupted in 1984 and 1988 from Mount Erebus, Antarctica. The 1984 and 1988 glasses have slightly different ({sup 230}Th)/({sup 232}Th) ratios but both have a 10% excess of ({sup 230}Th) over ({sup 238}U) and equilibrium ({sup 228}Th) values. By comparing these data and Pb-isotopic data reported in SUN and HANSON (1975) to similar data for oceanic basalts, the duration of differentiation from basanite to phonolite is limited to less than 150,000 years. The anorthoclase separates have ({sup 230}Th)/({sup 238}U) ratios exceeding those of the associated glasses but have ({sup 230}Th)/({sup 232}Th) ratios like those of the glasses. Both glasses are depleted in {sup 226}Ra with respect to {sup 230}Th by about 25%, whereas associated anorthoclase separates have extreme excesses of {sup 226}Ra over {sup 230}Th and ({sup 228}Th)/({sup 232}Th) = 2.2. On a plot of ({sup 226}Ra)/Ba vs. ({sup 230}Th)/BA, the glass-anorthoclase pairs produce isochrons averaging 2,380 y, which represents the average age of anorthoclase growth in the shallow magma system at Erebus. The implied residence time of phonolite magmas in the shallow magma chamber system of Erebus is about 3,000 y. Final crystal growth occurred after intrusion into the convecting lava lake less than decades before eruption.

  10. Projectile-breakup-induced fission-fragment angular distributions in the 6Li+232Th reaction

    NASA Astrophysics Data System (ADS)

    Pal, A.; Santra, S.; Chattopadhyay, D.; Kundu, A.; Ramachandran, K.; Tripathi, R.; Roy, B. J.; Nag, T. N.; Sawant, Y.; Sarkar, D.; Nayak, B. K.; Saxena, A.; Kailas, S.

    2017-08-01

    Background: Experimental anisotropy in fission-fragment (FF) angular distribution in reactions involving weakly bound stable projectiles with actinide targets are enhanced compared to statistical saddle-point model (SSPM) predictions. Contributions from breakup- or transfer-induced fission to total fission are cited as possible reasons for such enhancement. Purpose: To identify the breakup- or transfer-induced fission channels in 6Li+232Th reaction and to investigate their effects on FF angular anisotropy. Methods: The FF angular distributions have been measured exclusively at three beam energies (28, 32, and 36 MeV) around the Coulomb barrier in coincidence with projectile breakup fragments like α , d , and p using Si strip detectors. The angular anisotropy obtained for different exclusive breakup- or transfer-induced fission channels are compared with that for total fission. SSPM and pre-equilibrium fission models have been employed to obtain theoretical FF angular anisotropy. Results: Angular anisotropy of the fission fragments produced by different transfer- or breakup-induced fission reactions have been obtained separately in the rest frame of respective recoiling nuclei. Some of these anisotropies were found to be stronger than those of the inclusive fission. Overall angular distributions of transfer or breakup fission, integrated over all possible recoil angles with weight factor proportional to differential cross section of the complementary breakup fragment emitted in coincidence in all possible directions, were obtained. It was observed that the overall FF angular anisotropy for each of these fission channels is less than or equal to the anisotropy of total fission at all the measured energies. Assuming isotropic out-of-plane correlations between the fission fragments and light-charged particles, the overall breakup- or transfer-induced fission fragment angular distributions do not explain the observed enhancement in FF anisotropy of total fission. Pre

  11. Retardation of 238U and 232Th decay chain radionuclides in Long Island and Connecticut aquifers

    NASA Astrophysics Data System (ADS)

    Copenhaver, Sally A.; Krishnaswami, S.; Turekian, Karl K.; Epler, Nathan; Cochran, J. K.

    1993-02-01

    Knowledge of the ability of an aquifer to retard the groundwater transport of toxic or radioactive ions can be inferred from the analysis of groundwater for the radionuclides of the 238U- and 232Th-decay chains. Groundwaters of varying chemical composition were analyzed from wells in Long Island, New York, and Connecticut. Aquifer lithologies are arkose, quartz sandstone, granite, and glacial drift. Adsorption ( k1) and desorption ( k2) coefficients for Ra and Pb were calculated using 222Rn activity as a measure of the supply of other α-recoil nuclides. Laboratory tests of the validity of this assumption were made by measuring the flux of 224Ra and 222Rn from aquifer solids. The ratio k 1/k 2 is the distribution coefficient, K, which is effectively equal to R ƒ, the retardation factor. The average value of K for Ra is 6 × 10 2 in Long Island aquifers and 5 × 10 4 in Connecticut. The distribution coefficient for Pb is 10 4 in Long Island and 10 5 in Connecticut. Results from this and other studies reveal a strong dependence of retardation on pH, ƒ O 2, and ionic strength that tends to overwhelm any dependence of retardation on lithology.

  12. Mass distribution and mass resolved angular distribution of fission products in 28Si+232Th

    NASA Astrophysics Data System (ADS)

    Sodaye, Suparna; Tripathi, R.; John, B. V.; Ramachandran, K.; Pujari, P. K.

    2017-01-01

    Background: Fission process with heavier projectiles and actinide targets has contributions from processes, such as compound nucleus fission, transfer-induced fission, and noncompound nucleus fission. Mass distribution and mass-dependent anisotropy can be used to identify and delineate the contributions due to these different processes. Purpose: Mass distribution in 28Si+232Th has been studied at beam energies of 180 and 158 MeV to investigate the nature of mass distribution arising from complete and incomplete momentum-transfer fission events. Mass-dependent angular anisotropy has been measured at 166 MeV to investigate the dominant noncompound nucleus process contributing to the fission. Method: Mass distribution and mass resolved angular distribution of fission products were measured by the recoil catcher method followed by off-line γ -ray spectrometry. Results: Mass distributions for full momentum-transfer fission processes were found to be symmetric, and those for transfer-induced fission were found to be asymmetric at both beam energies. The relative contribution from transfer-induced fission was found to be higher at lower beam energy. The anisotropy of the fission product angular distribution was found to increase with decreasing mass asymmetry. Conclusions: The mass distribution indicates that, apart from the full momentum-transfer fission process, there is a significant contribution due to transfer-induced fission. The mass dependence of angular anisotropy indicated that preequilibrium fission is the dominant noncompound nucleus process in the present reaction system at near barrier energy (Ec .m ./VC=1.06 ) .

  13. New evaluation of the{sup 232}Th resonance parameters in the energy range

    SciTech Connect

    Derrien, H.; Leal, L. C.; Larson, N. M.

    2006-07-01

    Neutron resonance parameters of {sup 232}Th were obtained from a Reich-Moore SAMMY analysis of high-resolution neutron transmission measurements performed at the Oak Ridge Linear Accelerator (ORELA) by Olsen et al. in 1981 and of high-resolution neutron capture measurements performed recently at the Geel Linear Accelerator (GELINA (Belgium)) by Schillebeeckx et al. and at n-TOF (CERN (Switzerland)) by Aerts et al. The ORELA data were analyzed previously by Olsen using the Breit-Wigner multilevel code SIOB, and their results were used for the ENDF/B-VI evaluation. In our new analysis of the Olsen neutron transmissions using the modern computer code SAMMY, better accuracy is obtained for the resonance parameters by including recent experimental neutron capture data in the experimental data base. The experimental data base and the method of analysis are described in the report. Neutron transmissions and capture cross sections calculated with the resonance parameters are compared to the experimental values. A description is given of the statistical properties of the resonance parameters. The new evaluation produces a decrease in the capture resonance integral, and improves the prediction of integral thermal benchmarks. (authors)

  14. Study of 232Th(n, γ) and 232Th(n,f) reaction rates in a graphite moderated spallation neutron field produced by 1.6 GeV deuterons on lead target

    NASA Astrophysics Data System (ADS)

    Asquith, N. L.; Hashemi-Nezhad, S. R.; Westmeier, W.; Zhuk, I.; Tyutyunnikov, S.; Adam, J.

    2015-02-01

    The Gamma-3 assembly of the Joint Institute for Nuclear Research (JINR), Dubna, Russia is designed to emulate the neutron spectrum of a thermal Accelerator Driven System (ADS). It consists of a lead spallation target surrounded by reactor grade graphite. The target was irradiated with 1.6 GeV deuterons from the Nuclotron accelerator and the neutron capture and fission rate of 232Th in several locations within the assembly were experimentally measured. 232Th is a proposed fuel for envisaged Accelerator Driven Systems and these two reactions are fundamental to the performance and feasibility of 232Th in an ADS. The irradiation of the Gamma-3 assembly was also simulated using MCNPX 2.7 with the INCL4 intra-nuclear cascade and ABLA fission/evaporation models. Good agreement between the experimentally measured and calculated reaction rates was found. This serves as a good validation for the computational models and cross section data used to simulate neutron production and transport of spallation neutrons within a thermal ADS.

  15. The Concentrations of {sup 40}K, {sup 226}Ra and {sup 232}Th in Soil Sample in Osmaniye (Turkey)

    SciTech Connect

    Akkurt, I.; Guenoglu, K.; Kara, A.; Mavi, B.; Karaboerklue, S.

    2011-12-26

    The {sup 40}K, {sup 226}Ra and {sup 232}Th concentration is due to the magmatic structure of the earth and it can be varied from place to place. Osmaniye is located in the Eastern side of Mediteranean Region. It holds the climatic characteristics of the same region and arises with Middle Taurus Mountains from west to North and with Amonos Mounations in East and West-east parts and is situated between 35 deg. .52'-36 deg. .42' east longitudes and 36 deg. .57'-37 deg. .45' north latitudes. In this study, the natural radioactivity concentrations {sup 40}K, {sup 226}Ra and {sup 232}Th in some soil samples collected in Osmaniye have been investigated. The measurements have been performed using 3x3{sup ''} NaI(Tl) detector system.

  16. Quasi-elastic scattering and transfer angular distribution for B,1110+232Th systems at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Dubey, Shradha; Biswas, D. C.; Mukherjee, S.; Patel, D.; Gupta, Y. K.; Prajapati, G. K.; Joshi, B. N.; Danu, L. S.; Mukhopadhyay, S.; John, B. V.; Suryanarayana, S. V.; Vind, R. P.

    2016-12-01

    Quasi-elastic scattering and transfer angular distributions for B,1110+232Th reactions have been measured simultaneously in a wide range of bombarding energies around the Coulomb barrier. The quasi-elastic angular distribution data are analyzed using the optical model code ecis with phenomenological Woods-Saxon potentials. The obtained potential parameters suggest the presence of usual threshold anomaly, confirming tightly bound characteristics for both the projectiles. The reaction cross sections are obtained from the fitting of quasi-elastic angular distribution data. The reduced cross sections at sub-barrier energies compared with Li,76+232Th systems show a systematic dependence on projectile breakup energy. The angular distribution of the transfer products show similar behavior for both the systems.

  17. Covariance data for{sup 232}Th in the resolved resonance region from 0 to 4 keV

    SciTech Connect

    Leal, L. C.; Derrien, H.; Arbanas, G.; Larson, N. M.; Wiarda, D.

    2006-07-01

    This paper reports on the generation and testing of the covariance matrix associated with the resonance parameter evaluation for {sup 232}Th up to 4 keV. [1] Covariance data are required to correctly assess uncertainties in design parameters in nuclear applications. The error estimation of calculated quantities relies on the nuclear data uncertainty information available in the basic nuclear data libraries, such as the US Evaluated Nuclear Data Library, ENDF/B. Uncertainty files in the ENDF/B library are obtained from analysis of experimental data and are stored as variance and covariance data. In this paper, we address the generation of covariance data in the resonance region via the computer code SAMMY, which is used in the evaluation of experimental data in the resolved and unresolved resonance energy regions. The resolved resonance parameter covariance matrix for {sup 232}Th, obtained using the retroactive approach, is also presented here. (authors)

  18. Radium-226, 232Th, and 40K distribution in the environment of Kaiga of south west coast of India.

    PubMed

    Karunakara, N; Somashekarappa, H M; Avadhani, D N; Mahesh, H M; Narayana, Y; Siddappa, K

    2001-05-01

    Systematic studies on gamma radiation level and the distribution of natural radionuclides were carried out under a pre-operational survey for the establishment of baseline data on background radiation level and the distribution of radio-nuclides in the environment of Kaiga, in the south west coast of India, where a nuclear power reactor of 235 MWe has just been commissioned. The external gamma absorbed dose rates prevailing in the region were measured using a portable plastic scintillometer. Soil samples from 18 stations were collected from depth intervals of 0-5, 5-10, and 10-25 cm and analyzed for their 226Ra, 232Th, and 40K activity concentrations by gamma spectrometry employing a 90 cc PGT HpGe detector coupled to an EG&G ORTEC 8K multichannel analyzer. The activity of 226Ra was found to vary between 15.5-61.2 Bq kg(-1) with a mean value of 31.3 Bq kg(-1), that of 232Th varies between 11.4-41.9 Bq kg(-1) with a mean value of 27.5 Bq kg(-1) and of 40K between 78.3-254.8 Bq kg(-1) with a mean value of 159.9 Bq kg(-1) in 0-5 cm soil profiles of the region. The contributions of 238U, 232Th, and 40K to the total gamma absorbed dose rate were 39.9%, 40.7%, and 16.0%, respectively. The gamma absorbed dose rate in air estimated using the results of activity concentration of 226Ra, 232Th, and 40K are found to compare well with that of the direct measurement. The results of the study were compared with the literature values reported for other environs of the country as well as the world, and conclusions are drawn.

  19. Development of a method for activity measurements of 232Th daughters with a multidetector gamma-ray coincidence spectrometer.

    PubMed

    Antovic, N; Svrkota, N

    2009-06-01

    The method for activity measurements of the (232)Th daughters, developed at the six-crystal gamma-ray coincidence spectrometer PRIPYAT-2M and based on coincidence counting of the 583 and 2615 keV photons from cascade transitions which follow beta(-)-decay of (208)Tl, as well as on counting the 911 keV photons which follow beta(-)-decay of (228)Ac in the integral and non-coincidence mode of counting, is presented.

  20. [About the contents of 40K, 226Ra and 232Th in forest soils of the Republic of Belarus].

    PubMed

    Perevolotskiĭ, A N; Perevolotskaia, T V

    2014-01-01

    The specific activity of 40K, 232Th and 226Ra in forest soil ecotopes (A2-B2-C2-D2) has been investigated. When the fertility of the soil increases from A2 to D2, then the specific activity of 40K increases in the rooting zone of the soil from 275 ± 6.9 up to 499 ± 11 Bq/kg, 232Th--from 11.8 ± 0.5 to 17.1 ± 1.1 Bq/kg, 226Ra- from 19.2 γ 0.8 to 27.9 ± 1.5 Bq/kg. The calculated capacity of the absorbed dose of γ-radiation conditioned by 40K, 232Th and 226Ra increases from A2 to D2 from 27.5 ± 0.5 to 44.1 ± 1.1 nGy / h at the height of 1 m.

  1. Solubility assessment of 232Th from various types of soil in Malaysia using USP and DIN In Vitro digestion method

    NASA Astrophysics Data System (ADS)

    Rashid, Nur Shahidah Abdul; Perama, Yasmin Mohd Idris; Salih, Fitri Hakeem Mohd; Sarmani, Sukiman; Majid, Amran Ab.; Siong, Khoo Kok

    2016-11-01

    The overall results of the study showed that the concentrations of 232Th radionuclide using DIN digestion method during gastric phase are 0.0015 mg/kg - 0.0554 mg/kg and 0.0015 mg/kg - 0.0139 mg/kg during intestinal phase, respectively. As for USP digestion method during gastric phase are between 0.0877 mg/kg - 0.4964 mg/kg and 0.0207 mg/kg - 0.2291 mg/kg. The results from the measurements in various types of soils indicates some elevation of 232Th concentration in some types of soil compared to UNSCEAR reference values, in which may be a result from the impact of previous mining activity in the surrounding area and considered to be safe. In general, the results of 232Th concentrations from in vitro extraction technique is considered to be safe. By natural processes, thorium ingestion is getting transferred to living beings through different pathways and need to be monitored in order to assess possible hazards. Environmental studies are generally carried out to trace the pathway of radionuclides/radiotoxic elements to reach living organism. Environmental monitoring and meaningful interpretation of data from man-made pollution are more complicated without adequate knowledge about the natural abundance of radioactive elements in the environment.

  2. (226)Ra, (232)Th and (40)K contents in soil samples from Garhwal Himalaya, India, and its radiological implications.

    PubMed

    Ramola, R C; Gusain, G S; Badoni, Manjari; Prasad, Yogesh; Prasad, Ganesh; Ramachandran, T V

    2008-09-01

    The exposure of human beings to ionising radiation from natural sources is a continuing and inescapable feature of life on earth. Natural radionuclides are widely distributed in various geological formations and ecosystems such as rocks, soil groundwater and foodstuffs. In the present study, the distribution of (226)Ra, (232)Th and (40)K was measured in soil samples collected from different lithological units of the Thauldhar and Budhakedar regions of Garhwal Himalaya, India. The collected soil samples were analysed using gamma ray spectrometry. The activity concentrations of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K in these soil samples were found to vary from below detection level (BDL) to 131 +/- 18 Bq kg(-1), 9 +/- 6 to 384 +/- 53 Bq kg(-1) and 471 +/- 96 to 1406 +/- 175 Bq kg(-1), respectively. The distribution of radionuclides depends upon the rock formation and chemical properties within the earth. The activity concentrations vary widely depending on the sample origin. The external absorbed gamma dose rates due to (226)Ra, (232)Th and (40)K were found to vary from 49 to 306 nGy h(-1). The average radium equivalent activity from these soil samples was 300 Bq kg(-1).

  3. Physical characteristics of LWRs and SCLWRs loaded by ({sup 233}U-Th-{sup 238}U) oxide fuel with small additions of {sup 231}Pa

    SciTech Connect

    Kulikov, E.G.; Shmelev, A.N.; Apse, V.A.; Kulikov, G.G.

    2007-07-01

    The paper investigates the possibility and attractiveness of using (U-Th) fuel in light-water reactors (LWRs) and in light-water reactors with super-critical coolant parameters (SCLWRs). It is proposed to dilute {sup 233}U with {sup 238}U to enhance the proliferation resistance of this fissionable isotope. If is noteworthy that she idea was put forward for the first time by she well known American physicist and participant of the Manhattan Project Dr. T. Taylor. Various fuel compositions are analyzed and compared on fuel breeding, achievable values of fuel burn-up and cross-sections of parasitic neutron absorption. It is also demonstrated that small {sup 231}Pa additions (several percent) into the fuel allows: to increase fuel burn-up, to achieve more negative temperature reactivity coefficient of coolant and to enhance nonproliferation of the fuel. (authors)

  4. Cross sections of the reaction {sup 231}Pa(d,3n){sup 230}U for the production of {sup 230}U/{sup 226}Th for targeted {alpha} therapy

    SciTech Connect

    Morgenstern, A.; Bruchertseifer, F.; Zielinska, B.; Apostolidis, C.; Lebeda, O.; Stursa, J.; Capote, R.; Sin, M.

    2009-11-15

    {sup 230}U and its daughter nuclide {sup 226}Th are novel therapeutic nuclides for application in targeted {alpha} therapy of cancer. We investigated the feasibility of producing {sup 230}U/{sup 226}Th via deuteron irradiation of {sup 231}Pa according to the reaction {sup 231}Pa(d,3n){sup 230}U. The experimental excitation function for a deuteron-induced reaction on {sup 231}Pa is reported for the first time. Cross sections were measured using thin targets of {sup 231}Pa prepared by electrodeposition and {sup 230}U yields were analysed using {alpha} spectrometry. Beam energies were calculated from measured beam orbits and compared with the values obtained via monitor reactions on aluminium foils using high-resolution {gamma} spectrometry and IAEA recommended cross sections. Beam intensities were determined using a beam current integrator. The experimental cross sections are in excellent agreement with model calculations allowing for deuteron breakup using the EMPIRE 3 code. According to thick-target yields calculated from the experimental excitation function, the reaction {sup 231}Pa(d,3n){sup 230}U allows the production of {sup 230}U/{sup 226}Th at moderate levels.

  5. Measurement of fission cross section for 232Th (n,f) 131 ZX ( Z = 50 , 51, 52, 53) reaction induced by neutrons around 14 MeV

    NASA Astrophysics Data System (ADS)

    Lan, Chang-lin; Qiu, Yi-jia; Wang, Qiang; Zhang, Zheng-wei; Zhang, Qian; Tan, Jun-cai; Lai, Cai-feng; Fang, Kai-hong

    2017-06-01

    The fission cross sections of 232Th (n,f) 131m, gSn , 232Th (n,f) 131Sb , 232Th (n,f) 131m, gTe , 232Th (n,f) 131I fission reactions induced by 14MeV neutrons were measured precisely with the neutron activation technique. The neutron flux was monitored by accompanying α particle in the irradiation and the neutron energies were determined by the cross section ratio of 90Zr (n,2n) 89Zr to 93Nb (n,2n) 92mNb reaction. The values of the cross sections of 232Th (n,f) 131m, gSn were analyzed, and the cross sections of 232Th (n,f) 131Sb were deduced to be 6.5± 0.7 , 6.3± 0.6 , 6.1± 0.6 mb at 14.1± 0.3 , 14.5± 0.3 and 14.8± 0.3 MeV, respectively. The values of the cross sections of 232Th (n,f) 131gTe were deduced to be 1.8± 0.1 , 1.5± 0.1 and 1.4± 0.1 mb at 14.1± 0.3 , 14.5± 0.3 and 14.8± 0.3 MeV, respectively. The values of the cross sections of 232Th (n,f) 131I were given as 1.8± 0.2 , 1.6± 0.2 , 1.5± 0.1 mb at 14.1± 0.3 , 14.5± 0.3 and 14.8± 0.3 MeV, respectively.

  6. Measurement of Neutron-Induced Fission Cross Sections of {sup 229}Th and {sup 231}Pa Using Linac-Driven Lead Slowing-Down Spectrometer

    SciTech Connect

    Kobayashi, Katsuhei; Yamamoto, Shuji; Lee, Samyol; Cho, Hyun-Je; Yamana, Hajimu; Moriyama, Hirotake; Fujita, Yoshiaki; Mitsugashira, Toshiaki

    2001-11-15

    Use is made of a back-to-back type of double fission chamber and an electron linear accelerator-driven lead slowing-down spectrometer to measure the neutron-induced fission cross sections of {sup 229}Th and {sup 231}Pa below 10 keV relative to that of {sup 235}U. A measurement relative to the {sup 10}B(n, {alpha}) reaction is also made using a BF{sub 3} counter at energies below 1 keV and normalized to the absolute value obtained by using the cross section of the {sup 235}U(n,f) reaction between 200 eV and 1 keV.The experimental data of the {sup 229}Th(n,f) reaction, which was measured by Konakhovich et al., show higher cross-section values, especially at energies of 0.1 to 0.4 eV. The data by Gokhberg et al. seem to be lower than the current measurement above 6 keV. Although the evaluated data in JENDL-3.2 are in general agreement with the measurement, the evaluation is higher from 0.25 to 5 eV and lower above 10 eV. The ENDF/B-VI data evaluated above 10 eV are also lower. The current thermal neutron-induced fission cross section at 0.0253 eV is 32.4 {+-} 10.7 b, which is in good agreement with results of Gindler et al., Mughabghab, and JENDL-3.2.The mean value of the {sup 231}Pa(n,f) cross sections between 0.37 and 0.52 eV, which were measured by Leonard and Odegaarden, is close to the current measurement. The evaluated data in ENDF/B-VI are lower below 0.15 eV and higher above {approx}30 eV. The ENDF/B-VI and the JEF-2.2 are extremely higher above 1 keV. The JENDL-3.2 data are in general agreement with the measurement, although they are lower above {approx}100 eV.

  7. Radionuclide ((226)Ra, (232)Th, (40)K) accumulation among plant species in mangrove ecosystems of Pattani Bay, Thailand.

    PubMed

    Kaewtubtim, Pungtip; Meeinkuirt, Weeradej; Seepom, Sumalee; Pichtel, John

    2017-02-15

    Little is known regarding phytoremediation of radionuclides from soil; even less is known about radionuclide contamination and removal in tropical ecosystems such as mangrove forests. In mangrove forests in Pattani Bay, Thailand, 18 plant species from 17 genera were evaluated for radionuclide concentrations within selected plant parts. Two shrub species, Avicennia marina and Pluchea indica, accumulated the highest (232)Th (24.6Bqkg(-1)) and (40)K (220.7Bqkg(-1)) activity concentrations in roots, respectively. Furthermore, the aquatic species Typha angustifolia accumulated highest (232)Th, (40)K and (226)Ra activity concentrations (85.2, 363.5, 16.6Bqkg(-1), respectively) with the highest transfer factors (TFs) (3.0, 2.0, 5.9, respectively) in leaves. Leaves of T. angustifolia had an absorbed dose rate in air (D) over the recommended value (74.8nGyh(-1)) that was considered sufficiently high to be of concern for human consumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Primordial radioactivity ((238)U, (232)Th and (40)K) measurements for soils of Ludhiana district of Punjab, India.

    PubMed

    Badhan, K; Mehra, R

    2012-11-01

    The aim of the present work was to study the activity concentration and absorbed gamma dose rates due to primordial radionuclides ((238)U, (232)Th and (40)K) for the soil of different villages of Ludhiana district of Punjab, India using a high-purity germanium detector based on high resolution gamma-ray spectrometry. The average activity concentrations of (238)U, (232)Th and (40)K in the soil samples have been found to be 28.58, 50.95 and 569.59 Bq kg(-1), respectively, which gives the total gamma dose rate contribution of 68.50 nGy h(-1). To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the external hazard index, the absorbed dose rate and the effective dose rate have been calculated. The calculated radium equivalent activity values are on the lower side of the recommended safe limit value of 370 Bq kg(-1) by Organization of Economic and Control Department. The calculated value of external health hazard index is lower than unity.

  9. Natural radioactivity (226Ra, 232Th and 40K) and assessment of radiological hazards in the Kestanbol granitoid, Turkey.

    PubMed

    Canbaz, Buket; Cam, N Füsun; Yaprak, Günseli; Candan, Osman

    2010-09-01

    The surveys of natural gamma-emitting radionuclides in rocks and soils from the Ezine plutonic area were conducted during 2007. Direct dose measurement using a survey meter was carried out simultaneously. The present study, which is part of the survey, analysed the activity concentrations of (238)U, (232)Th and (40)K in granitoid samples from all over the region by HPGe gamma spectrometry. The activity concentrations of (226)Ra ranged from 94 to 637 Bq kg(-1), those of (232)Th ranged from 120 to 601 Bq kg(-1)and those of (40)K ranged from 1074 to 1527 Bq kg(-1) in the analysed rock samples from different parts of the pluton. To evaluate the radiological hazard of the natural radioactivity in the samples, the absorbed dose rate (D), the annual effective dose rate, the radium equivalent activity (Ra(eq)) and the external (H(ex)) hazard index were calculated according to the UNSCEAR 2000 report. The thorium-to-uranium concentration ratios were also estimated.

  10. Soil-to-root vegetable transfer factors for (226)Ra, (232)Th, (40)K, and (88)Y in Malaysia.

    PubMed

    Asaduzzaman, Kh; Khandaker, Mayeen Uddin; Amin, Y M; Bradley, D A; Mahat, R H; Nor, R M

    2014-09-01

    Soil-to-plant transfer factors (TFs) are of fundamental importance in assessing the environmental impact due to the presence of radioactivity in soil and agricultural crops. Tapioca and sweet potato, both root crops, are popular foodstuffs for a significant fraction of the Malaysian population, and result in intake of radionuclides. For the natural field conditions experienced in production of these foodstuffs, TFs and the annual effective dose were evaluated for the natural radionuclides (226)Ra, (232)Th, (40)K, and for the anthropogenic radionuclide (88)Y, the latter being a component of fallout. An experimental tapioca field was developed for study of the time dependence of plant uptake. For soil samples from all study locations other than the experimental field, it has been shown that these contain the artificial radionuclide (88)Y, although the uptake of (88)Y has only been observed in the roots of the plant Manihot esculenta (from which tapioca is derived) grown in mining soil. The estimated TFs for (226)Ra and (232)Th for tapioca and sweet potato are very much higher than that reported by the IAEA. For all study areas, the annual effective dose from ingestion of tapioca and sweet potato are estimated to be lower than the world average (290 μSv y(-1)). Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Covariances of Evaluated Nuclear Cross Section Data for (232)Th, (180,182,183,184,186)W and (55)Mn

    SciTech Connect

    Trkov, A.; Capote, R.; Soukhovitskii, E; Leal, Luiz C; Sin, M; Kodeli, I.; Muir, D W

    2011-01-01

    The EMPIRE code system is a versatile package for nuclear model calculations that is often used for nuclear data evaluation. Its capabilities include random sampling of model parameters, which can be utilized to generate a full covariance matrix of all scattering cross sections, including cross-reaction correlations. The EMPIRE system was used to prepare the prior covariance matrices of reaction cross sections of (232)Th, (180,182,183,184,186)W and (55)Mn nuclei for incident neutron energies up to 60 MeV. The obtained modeling prior was fed to the GANDR system, which is a package for a global assessment of nuclear data, based on the Generalized Least-Squares method. By introducing experimental data from the EXFOR database into GANDR, the constrained covariance matrices and cross section adjustment functions were obtained. Applying the correction functions on the cross sections and formatting the covariance matrices, the final evaluations in ENDF-6 format including covariances were derived. In the resonance energy range, separate analyses were performed to determine the resonance parameters with their respective covariances. The data files thus obtained were then subjected to detailed testing and validation. Described evaluations with covariances of (232)Th, (180,182,183,184,186)W and (55)Mn nuclei are included into the ENDF/B-VII.1 library release.

  12. A dispersive optical model potential for nucleon induced reactions on 238U and 232Th nuclei with full coupling

    NASA Astrophysics Data System (ADS)

    Quesada, José Manuel; Soukhovitskiĩ, EfremS.; Capote, Roberto; Chiba, Satoshi

    2013-03-01

    A dispersive coupled-channel optical model potential (DCCOMP) that couples the ground-state rotational and low-lying vibrational bands of 238U and 232Th nuclei is studied. The derived DCCOMP couples almost all excited levels below 1 MeV of excitation energy of the corresponding even-even actinides. The ground state, octupole, beta, gamma, and non-axial bands are coupled. The first two isobar analogue states (IAS) populated in the quasi-elastic (p,n) reaction are also coupled in the proton induced calculation, making the potential approximately Lane consistent. The coupled-channel potential is based on a soft-rotor description of the target nucleus structure, where dynamic vibrations are considered as perturbations of the rigid rotor underlying structure. Matrix elements required to use the proposed structure model in Tamura coupled-channel scheme are derived. Calculated ratio R(U238/Th232) of the total cross-section difference to the averaged σT for 238U and 232Th nuclei is shown to be in excellent agreement with measured data.

  13. Covariances of Evaluated Nuclear Cross Section Data for 232Th, 180,182,183,184,186W and 55Mn

    NASA Astrophysics Data System (ADS)

    Trkov, A.; Capote, R.; Soukhovitskii, E. Sh.; Leal, L. C.; Sin, M.; Kodeli, I.; Muir, D. W.

    2011-12-01

    The EMPIRE code system is a versatile package for nuclear model calculations that is often used for nuclear data evaluation. Its capabilities include random sampling of model parameters, which can be utilised to generate a full covariance matrix of all scattering cross sections, including cross-reaction correlations. The EMPIRE system was used to prepare the prior covariance matrices of reaction cross sections of 232Th, 180,182,183,184,186W and 55Mn nuclei for incident neutron energies up to 60 MeV. The obtained modelling prior was fed to the GANDR system, which is a package for a global assessment of nuclear data, based on the Generalised Least-Squares method. By introducing experimental data from the EXFOR database into GANDR, the constrained covariance matrices and cross section adjustment functions were obtained. Applying the correction functions on the cross sections and formatting the covariance matrices, the final evaluations in ENDF-6 format including covariances were derived. In the resonance energy range, separate analyses were performed to determine the resonance parameters with their respective covariances. The data files thus obtained were then subjected to detailed testing and validation. Described evaluations with covariances of 232Th, 180,182,183,184,186W and 55Mn nuclei are included into the ENDF/B-VII.1 library release.

  14. Evaluation of the 232Th Neutron Cross Sections between 4 keV and 140 keV

    SciTech Connect

    Volev, K.; Koyumdjieva, N.; Brusegan, A.; Borella, A.; Siegler, P.; Schillebeeckx, P.; Janeva, N.; Lukyanov, A.; Leal, L.

    2005-05-24

    An evaluation of the 232Th neutron total and capture cross sections has been performed in the energy region between 4 keV and 140 keV. The evaluation results from a simultaneous analysis of capture, transmission, and self-indication measurement data, including the most recent capture cross-section data obtained at the GELINA facility of the Institute for Reference Materials and Measurements at Geel (B) and at the n-TOF facility at CERN (CH). The experimental data have been analysed in terms of average resonance parameters exploiting two independent theoretical approaches -- the Characteristic Function model and the Hauser-Feshbach-Moldauer theory. The resulting parameters are consistent with the resolved resonance parameters deduced from the transmission measurements of Olsen et al. at the ORELA facility.

  15. Measurement of resolved resonances of 232Th(n,γ) at the n_TOF facility at CERN

    NASA Astrophysics Data System (ADS)

    Gunsing, F.; Berthoumieux, E.; Aerts, G.; Abbondanno, U.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillman, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krtička, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2012-06-01

    The yield of the neutron capture reaction 232Th(n,γ) has been measured at the neutron time-of-flight facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The reduction of the acquired data to the capture yield for resolved resonances from 1 eV to 4 keV is described and compared to a recent evaluated data set. The resonance parameters were used to assign an orbital momentum to each resonance. A missing level estimator was used to extract the s-wave level spacing of D0=17.2±0.9 eV.

  16. Deep Equatorial Atlantic Ocean Circulation over the Last 25,000 Years - Insights from 231Pa/230Th, 14C and Sortable Silt Grain Size

    NASA Astrophysics Data System (ADS)

    Ng, H. C.; Robinson, L. F.; McManus, J. F.; Mohamed Falcon, K. J.; Jacobel, A. W.

    2014-12-01

    Evidence points to a key role of the Atlantic circulation in controlling climate changes during the last deglacial (20-10 ka), though quantifying the rate of past ocean circulation remains an open challenge. Existing Atlantic rate proxy records over the last deglacial exhibit pronounced differences both in timing and magnitudes at both deep and intermediate depths. This uncertainty calls for more rate proxy data at key sites to improve understanding of the driving mechanisms behind the Atlantic observations. This study examines three complementary rate proxies (231Pa/230Th, Δ14C and sortable silt grain size) of Equatorial Atlantic sediment cores from 2.7 to 4.1 km depth from the east and west of the Mid-Atlantic Ridge. Sediment cores from the Ceara Rise in the western basin (4.1 km depth; 3.3 km depth) support a picture of relatively 14C-depleted deep water with higher Pa/Th values during the Last Glacial Maximum compared to the modern day. During Heinrich Stadial 1, there is a marked increase in Pa/Th values. Measured opal fluxes indicate that opal scavenging is not the main driver of the observed Pa/Th changes. At the same time, radiocarbon data indicate that the most 14C-depleted signature occurs at around 3 km water depth. Sortable silt mean size also shows distinctive changes around this period, but with some offset in timing potentially related to changes in circulation rate at different scales. Results from two new cores collected on a recent cruise (JC094) will be used to extend our understanding of these Equatorial Atlantic glacial-deglacial rate proxy dynamics and their relative timings. Both cores were collected far from the continental margin, in the central and eastern Atlantic (7o26.10'N, 21o47.78'W, 3.4 km depth; 15o27.86'N, 50o59.49'W, 2.7 km depth) providing a synoptic basin scale view of these important rate tracers in the Atlantic.

  17. Cross-sections of the reaction 232Th(p,3n)230Pa for production of 230U for targeted alpha therapy.

    PubMed

    Morgenstern, Alfred; Apostolidis, Christos; Bruchertseifer, Frank; Capote, Roberto; Gouder, Thomas; Simonelli, Federica; Sin, Mihaela; Abbas, Kamel

    2008-10-01

    (230)U/(226)Th is a promising novel alpha-emitter system for application in targeted alpha therapy of cancer. The therapeutic nuclides can be produced by proton irradiation of natural (232)Th according to the reaction (232)Th(p,3n)(230)Pa, followed by subsequent beta decay of (230)Pa to (230)U. In this study, the experimental excitation function for the (232)Th(p,3n)(230)Pa reaction up to 34 MeV proton energy has been measured using the stacked-foil technique. The proton energies in the various foils were calculated with the SRIM 2003 code and gamma-ray spectrometry was used to measure the activities of the various radioisotopes produced. The measured cross-sections are in good agreement with selected literature values and with model calculations using the EMPIRE II code. The reaction (232)Th(p,3n)(230)Pa allows the production of carrier-free (230)U in clinically relevant levels.

  18. Retardation of [sup 238]U and [sup 232]Th decay chain radionuclides in Long Island and Connecticut aquifers

    SciTech Connect

    Copenhaver, S.A.; Krishnaswami, S.; Turekian, K.K. ); Epler, N.; Cochran, J.K. )

    1993-02-01

    Knowledge of the ability of an aquifer to retard the groundwater transport of toxic or radioactive ions can be inferred from the analysis of groundwater for the radionuclides of the [sup 238]U- and [sup 232]Th-decay chains. Groundwaters of varying chemical composition were analyzed from wells in Long Island, New York, and Connecticut. Aquifer lithologies are arkose, quartz sandstone, granite, and glacial drift. Adsorption (k[sub 1]) and desorption (k[sub 2]) coefficients for Ra and Pb were calculated using [sup 222]Rn activity as a measure of the supply of other [alpha]-recoil nuclides. Laboratory tests of the validity of this assumption were made by measuring the flux of [sup 224]Ra and [sup 222]Rn from aquifer solids. The ratio k[sub 1]/k[sub 2] is the distribution coefficient, K, which is effective equal to R[sub f], the retardation factor. The average value of K for Ra is 6 [times] 10[sup 2] in Long Island aquifers and 5 [times] 10[sup 4] in Connecticut. The distribution coefficient for Pb is 10[sup 4] in Long Island and 10[sup 5] in Connecticut. Results from this and other studies reveal a strong dependence of retardation on pH, f[sub o[sub 2

  19. Atmospheric aerosol measurements of 238U and 232Th at Fernald, Ohio, and implications on inhalation dose calculations.

    PubMed

    Leifer, Robert Z; Jacob, Ethel M; Marschke, Stephen F; Praniti, David M

    2002-12-01

    Measurements of the aerosol size distribution of 238U and 232Th at the U.S. Department of Energy's Fernald Environmental Management Project site were made to improve the inhalation dose calculations to off-site individuals. For approximately 1 y an 8-stage cascade impactor was co-located with a high volume sampler and operated at the Fernald Environmental Management Project site to collect aerosol samples. During most of the year, the site was dominated by giant particles with more than 70% of the mass of 238U above 15 microm. The seasonal average of the activity median aerodynamic diameter, based on the impactor samples, which excluded particles >15 microm, for both uranium and thorium was approximately 6.5 microm. These numbers reflect the activities at the site and the domination of the resuspension processes. During most sampling periods the size distribution was bimodal. Thorium concentrations were comparable to the uranium concentrations during the late spring and summer period and decreased to approximately 25% of the 238U concentration in the late summer. Fernald Environmental Management Project is required to calculate the maximum allowable dose from airborne emissions, excluding radon, to meet NESHAP compliance. These calculations assume an AMAD of 1 microm. We found that if you combine size distribution information with the latest ICRP 66 lung model you reduce the estimated dose by a factor of 7. Inclusion of the size distribution of radionuclides at any sampling site would substantially improve the dose estimates to the population.

  20. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O + 232Th reaction

    NASA Astrophysics Data System (ADS)

    Léguillon, R.; Nishio, K.; Hirose, K.; Makii, H.; Nishinaka, I.; Orlandi, R.; Tsukada, K.; Smallcombe, J.; Chiba, S.; Aritomo, Y.; Ohtsuki, T.; Tatsuzawa, R.; Takaki, N.; Tamura, N.; Goto, S.; Tsekhanovich, I.; Petrache, C. M.; Andreyev, A. N.

    2016-10-01

    It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O + 232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model.

  1. Correction methodology for the spectral interfering γ-rays overlapping to the analytical peaks used in the analysis of 232Th.

    PubMed

    Yücel, H; Köse, E; Esen, A N; Bor, D

    2011-06-01

    In the γ-ray spectrometric analysis of the radionuclides, a correction factor is generally required for the spectral interfering γ-rays in determining the net areas of the analytical peaks because some interfering γ-rays often might contribute to the analytical peaks of interest. In present study, a correction methodology for the spectral interfering γ-rays (CSI) is described. In particular, in the analysis of (232)Th contained in samples, the interfering γ-rays due to (226)Ra, (235)U, (238)U and their decay products often overlap to the peaks of interest from (232)Th decay products, and vise versa. For the validation of the proposed CSI method, several certified reference materials (CRM) containing U and Th were measured by using a 76.5% efficient n-type Ge detector. The required correction factors were quantified for spectral interference, self-absorption and true coincidence summing (TCS) effects for the relevant γ-rays. The measured results indicate that if one ignores the contributions of the interfering γ-rays to the analytical peaks at 583.2 keV of (208)Tl and 727.3 keV of (212)Bi, this leads to a significantly systematic influence on the resulted activities of (232)Th. The correction factors required for spectral interference and TCS effects are estimated to be ∼13.6% and ∼15.4% for 583.2 keV peak. For the 727.3 keV peak, the correction factor is estimated to be ∼15% for spectral interference, and ∼5% for the TCS effects at the presently used detection geometry. On the other hand, the measured results also indicate that ignoring the contribution of the interfering γ-rays to the areas of the analytical peaks at 860.6 keV of (208)Tl, 338.3 and 911.2 keV of (228)Ac does not lead to any significant systematic influence on the (232)Th analysis. Because these factors are remained generally less than ∼5%, i.e., within overall uncertainty limits. The present study also showed that in view of both the spectral interference and TCS effects, the

  2. A beta-alpha coincidence counting system for measurement of trace quantities of 238U and 232Th in aqueous samples at the Sudbury Neutrino Observatory.

    NASA Astrophysics Data System (ADS)

    Dawson, M.; Doucas, G.; Fergani, H.; Jelley, N. A.; Majerus, S.; O'Keeffe, H. M.; Peeters, S. J. M.; Perry, C.

    2016-08-01

    The Sudbury Neutrino Observatory experiment was built to measure the total flux of 8B solar neutrinos via the neutral current disintegration deuterium nuclei. This process can be mimiced by daughter isotopes of 232Th and 238U which can photodisintegrate the deuterium nucleus. Measurement of the concentration of such radioisotopes in the heavy water was critical to the success of the experiment. A radium assay technique using Hydrous Titanium Oxide coated filters was developed for this purpose and it was used in conjunction with a delayed beta-alpha coincidence counting system. The design, calibration and operation of this counting system are described in this paper. The counting efficiency for 232Th (224Ra) and 238U (226Ra) were measured to be 50 ± 5% and 62 ± 7%

  3. Determination of neutron capture cross sections of 232Th at 14.1 MeV and 14.8 MeV using the neutron activation method

    NASA Astrophysics Data System (ADS)

    Lan, Chang-Lin; Zhang, Yi; Lv, Tao; Xie, Bao-Lin; Peng, Meng; Yao, Ze-En; Chen, Jin-Gen; Kong, Xiang-Zhong

    2017-04-01

    The 232Th(n, γ)233Th neutron capture reaction cross sections were measured at average neutron energies of 14.1 MeV and 14.8 MeV using the activation method. The neutron flux was determined using the monitor reaction 27Al(n,α)24Na. The induced gamma-ray activities were measured using a low background gamma ray spectrometer equipped with a high resolution HPGe detector. The experimentally determined cross sections were compared with the data in the literature, and the evaluated data of ENDF/B-VII.1, JENDL-4.0u+, and CENDL-3.1. The excitation functions of the 232Th(n,γ)233Th reaction were also calculated theoretically using the TALYS1.6 computer code. Supported by Chinese TMSR Strategic Pioneer Science and Technology Project-The Th-U Fuel Physics Term (XDA02010100) and National Natural Science Foundation of China (11205076, 21327801)

  4. 226Ra, 232Th and 40K contents in water samples in part of central deserts in Iran and their potential radiological risk to human population

    PubMed Central

    2014-01-01

    Background The radiological quality of 226Ra, 232Th and 40K in some samples of water resources collected in Anarak-Khour a desertic area, Iran has been measured by direct gamma ray spectroscopy using high purity germanium detector in this paper. Result The concentration ranged from ≤0.5 to 9701 mBq/L for 226Ra; ≤0.2 to 28215 mBq/L for 232Th and < MDA to 10332 mBq/L for 40K. The radium equivalent activity was well below the defined limit of 370Bq/L. The calculated external hazard indices were found to be less than 1 which shows a low dose. Conclusion These results can be contributed to the database of this area because it may be used as disposal sites of nuclear waste in future. PMID:24883192

  5. Resonance Region Covariance Analysis Method and New Covariance Data for {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, and {sup 239}Pu

    SciTech Connect

    Leal, L.C. Arbanas, G.; Wiarda, D.; Derrien, H.

    2008-12-15

    Resonance-parameter covariance matrix (RPCM) evaluations in the resolved resonance region were done for {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, and {sup 239}Pu using the computer code SAMMY. The retroactive approach of the code SAMMY was used to generate the RPCMs for {sup 233}U and {sup 235}U. RPCMs for {sup 232}Th, {sup 238}U and {sup 239}Pu were generated together with the resonance parameter evaluations. The RPCMs were then converted in the ENDF format using the File32 representation. Alternatively, for computer storage reasons, the File32 was converted in the File33 cross section covariance matrix (CSCM). Both representations were processed using the computer code PUFF-IV. This paper describes the procedures used to generate the RPCM with SAMMY.

  6. Fission cross section of the 232Th(n,f)131Sb reaction induced by neutrons around 14 MeV

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Lv, Tao; Pan, Xiao-dong; Wang, Qiang; Fang, Kai-hong; Lan, Chang-lin

    2017-06-01

    In order to make a more detailed study on the 232Th fission process, the cross section of 232Th(n,f)131Sb fission reaction induced by 14 MeV neutrons was measured precisely with the neutron activation method and off-line gamma ray spectrometric technique. Neutron flux was monitored on line using the accompanying α particle from T(d,n)4He reaction in the irradiation and neutron energies were given by the cross section ratio of 90Zr(n,2 n)89Zr reaction to 93Nb(n,2 n)92 mNb reaction. The experimentally determined cross sections were deduced to be 6.27±0.47, 6.19±0.54, 6.00±0.51 mb at 14.1±0.3, 14.5±0.3 and 14.8±0.3 MeV, respectively.

  7. Comparison of activity concentration of 238U, 232Th and 40K in different Layers of subsurface Structures in Dei-Dei and Kubwa, Abuja, northcentral Nigeria

    NASA Astrophysics Data System (ADS)

    Maxwell, Omeje; Wagiran, Husin; Ibrahim, Noorddin; Lee, Siak Kuan; Sabri, Soheil

    2013-10-01

    The study of activity concentration of 232Th, 238U and 40K of rock samples from site one (S1L1-S1L11, 70 m) and site two (S2L1-S2L9, 60 m) boreholes in Dei-Dei and Kubwa was presented and the first time in the region to be compared. Activity concentrations were analysed using a high resolution co-axial HPGe gamma ray spectrometer system. The activity concentration ranges in site one borehole were from 45±1 to 98±6 Bq kg-1 for 232Th, from 18±2 to 37±4 Bq kg-1 for 238U and from 254 ±32 Bq kg-1 to 1195 ±151 Bq kg-1 for 40K. The activity concentration ranges in site two borehole were from 32±3 to 84±7 Bq kg-1 for 232Th, from 15±2 to 52±5 Bq kg-1 for 238U and from 119±15 to 705±94 for 40K Bq kg-1. Significantly higher concentration of 232Th and 238U occurs in samples collected from S1L7, S1L11 and S2L1 layers. These zones experienced granitic intrusions produced by denudation and tectonism. 40K in rock samples of S1L4 and S2L4 activity concentrations is close; it could be that biotite granitic intrusion that is inferred as the formation in that layer reflects the same activity of potassium in rock's radioactivity measurement. The area requires further investigation of soil geochemistry and activity concentration of radionuclides in groundwater.

  8. Measurement of 226Ra, 232Th, 137Cs and 40K activities of Wheat and Corn Products in Ilam Province – Iran and Resultant Annual Ingestion Radiation Dose

    PubMed Central

    CHANGIZI, Vahid; SHAFIEI, Elham; ZAREH, Mohammad Reza

    2013-01-01

    Background: Background: Natural background radiation is the main source of human exposure to radioactive material. Soils naturally have radioactive mineral contents. The aim of this study is to determine natural (238 U, 232 Th, 40 K) and artificial (137 Cs) radioactivity levels in wheat and corn fields of Eilam province. Methods: HPGe detector was used to measure the concentration activity of 238 U and 232 Th series, 40 K and 137 Cs in wheat and corn samples taken from different regions of Eilam province, in Iran. Results: In wheat and corn samples, the average activity concentrations of 226 Ra, 232 Th, 40 K and 137 Cs were found to be 1, 67, 0.5, 91.73, 0.01 and 0.81, 0.85, 101.52, 0.07 Bq/kg (dry weight), respectively. H ex and H in in the present work are lower than 1. The average value of H ex was found to be 0.02 and 0.025 and average value of H in to be found 0.025 and 0.027 in wheat fields samples and corn samples in Eilam provinces, respectively. The obtained values of AGDE are 30.49 mSv/yr for wheat filed samples and 37.89 mSv/yr for corn samples; the AEDE rate values are 5.28 mSv/yr in wheat filed samples and this average value was found to be 6.13 mSv/yr in corn samples in Eilam. Transfer factors (TFs) of long lived radionuclide such as 137 Cs, 226 Ra, 232 Th and 40 K from soils to corn and wheat plants have been studied by radiotracer experiments. Conclusion: The natural radioactivity levels in Eilam province are not at the range of high risk of morbidity and are under international standards. PMID:26056646

  9. STUDY OF NATURAL RADIOACTIVITY (226Ra, 232Th AND 40K) IN SOIL SAMPLES FOR THE ASSESSMENT OF AVERAGE EFFECTIVE DOSE AND RADIATION HAZARDS.

    PubMed

    Bangotra, Pargin; Mehra, Rohit; Kaur, Kirandeep; Jakhu, Rajan

    2016-10-01

    The activity concentration of (226)Ra (radium), (232)Th (thorium) and (40)K (potassium) has been measured in the soil samples collected from Mansa and Muktsar districts of Punjab (India) using NaI (Tikl) gamma detector. The concentration of three radionuclides ((226)Ra, (232)Th and (40)K) in the studied area has been varied from 18±4 to 46±5, 53±7 to 98±8 and 248±54 to 756±110 Bq kg(-1), respectively. Radium equivalent activities (Raeq) have been calculated in soil samples for the assessment of the radiation hazards arising due to the use of these soil samples. The absorbed dose rate of (226)Ra, (232)Th and (40)K in studied area has been varied from 8 to 21, 33 to 61 and 9 to 25 nGy h(-1), respectively. The corresponding indoor and outdoor annual effective dose in studied area was 0.38 and 0.09 mSv, respectively. The external and internal hazard has been also calculated for the assessment of radiation hazards in the studied area.

  10. Assay Methods for 238U, 232Th, and 210Pb in Lead and Calibration of 210Bi Bremsstrahlung Emission from Lead

    SciTech Connect

    Orrell, John L.; Aalseth, Craig E.; Arnquist, Isaac J.; Eggemeyer, Tere A.; Glasgow, Brian D.; Hoppe, Eric W.; Keillor, Martin E.; Morley, Shannon M.; Myers, Allan W.; Overman, Cory T.; Shaff, Sarah M.; Thommasson, Kimbrelle S.

    2016-02-13

    Assay methods for measuring 238U, 232Th, and 210Pb concentrations in refined lead are presented. The 238U and 232Th concentrations are assayed via inductively coupled plasma mass spectrometry (ICP-MS) after anion exchange column separation on dissolved lead samples. The 210Pb concentration is inferred through α-spectroscopy of a daughter isotope, 210Po, after chemical precipitation separation on dissolved lead samples. Subsequent to the 210Po α-spectroscopy assay, a method for evaluating 210Pb concentrations in solid lead samples was developed via measurement of bremsstrahlung radiation from β-decay of a daughter isotope, 210Bi, by employing a 14-crystal array of high purity germanium (HPGe) detectors. Ten sources of refined lead were assayed. The 238U concentrations were <34 microBq/kg and the 232Th concentrations ranged <0.6 – 15 microBq/kg, as determined by the ICP-MS assay method. The 210Pb concentrations ranged from ~0.1 – 75 Bq/kg, as inferred by the 210Po α-spectroscopy assay method.

  11. Measurement of cross sections for the {sup 232}Th(P,4n){sup 229}Pa reaction at low proton energies

    SciTech Connect

    Jost, C. U.; Griswold, J. R.; Bruffey, S. H.; Mirzadeh, S.; Stracener, D. W.; Williams, C. L.

    2013-04-19

    The alpha-emitters {sup 225}Ac and {sup 213}Bi are of great interest for alpha-radioimmunotherapy which uses radioisotopes attached to cancer-seeking antibodies to efficiently treat various types of cancers. Both radioisotopes are daughters of the long-lived {sup 229}Th(t{sub 1/2} = 7880y). {sup 229}Th can be produced by proton irradiation of {sup 232}Th and {sup 230}Th, either directly or through production of isobars that beta-decay into {sup 229}Th. To obtain excitation functions, {sup 232}Th and {sup 230}Th have been irradiated at the On-Line Test Facility at the Holifield Radioactive Ion Beam Facility at ORNL. Benchmark tests conducted with Cu and Ni foils show very good agreement with literature results. The experiments with thorium targets were focused on the production of {sup 229}Pa and its daughter {sup 225}Ac from both {sup 232}Th and {sup 230}Th. Differential cross-sections for production of {sup 229}Pa and other Pa isotopes have been obtained.

  12. Sources of alluvium in a coastal plain stream based on radionuclide signatures from the 238U and 232Th decay series

    NASA Astrophysics Data System (ADS)

    Yeager, Kevin M.; Santschi, Peter H.; Phillips, Jonathan D.; Herbert, Bruce E.

    2002-11-01

    Discerning alluvial sources and their change over time or distance is a fundamental question in hydrology and geology, often critical in identifying impacts of human and natural perturbations on fluvial systems. Surfaces of upland interfluves and subsoils, sources of alluvium in the lower Loco Bayou basin, Texas, were distinguished using the isotope ratios 226Ra/232Th, 226Ra/230Th, and 230Th/232Th. Channel alluvium indicates a transition from interfluve surface to subsoil sources during flood (subsoil ˜34% to ˜91%, over about 8 km) and bank-full stages (subsoil ˜9% to ˜74%, over about 12 km), with distance downstream. These results indicate strong coupling between hillslope and channel processes, reflecting land use change from forested to agricultural, concentrated in lower Loco Bayou. This methodology shows that sediment sources can be differentiated based upon landscape placement where lithologic contrast is absent. The geochemistry, long half-lives, and fractionation of 238U and 232Th decay series radionuclides during pedogenic and fluvial processes in humid climates suggest that these methods are applicable in a wide variety of fluvial systems.

  13. Activity concentration, transfer factors and resultant radiological risk of 226Ra, 232Th, and 40K in soil and some vegetables consumed in Selangor, Malaysia

    NASA Astrophysics Data System (ADS)

    Solehah, A. R.; Yasir, M. S.; Samat, S. B.

    2016-11-01

    The activity concentrations of the natural radionuclides 226Ra, 232Th, and 40K were determined in vegetable crops consumed by Malaysian people in Sungai Besar, Selangor. Sample of vegetables and the soil where the crops were cultivated and collected at five different location. The activity concentrations in Bq/kg of 226Ra, 232Th, and 40K were measured by the gamma-ray spectroscopy using the high purity germanium detector. The range activity concentration in soil is between 51.81 and 71.84 Bq/kg, 64.18 and 78.00 Bq/kg, and 210.49 and 244.29 Bq/kg for 226Ra, 232Th, and 40K, respectively. The activity concentration of 226Ra, 232Th, and 40K in vegetables were found to be in the range of 2.06 to 5.44 Bq/kg, Not Detectable to 0.61 Bq/kg, and 101.00 to 1223.09 Bq/kg, respectively. The activity concentration in both soil and vegetables were all less than lower limit stated by UNSCEAR. The Transfer Factors range value for 226Ra, 232Th, and 40K varied from 0.02 to 0.06, 0.003 to 0.008, and 1.79 to 5.19 respectively. Radium equivalent for soil range from 165.57 to 194.84 Bq/kg. It was within the international accepted value (370 Bq/kg). Absorb dose rate for soil range between 73.5 to 86.40 nGyh-1, in safe range from limit of international accepted value (55nGyh-1). Effective dose rate is found to be in range of 0.09 to 0.11 mSvy-1 for soil which is less than 2.4 mSv/y. External and Internal Hazard indices of soil was all below 1, within agreement of other researcher and UNSCEAR. The estimation of the consequent radiological risk due to the presence of those radionuclides is significantly low.

  14. Measurement of the Total Kinetic Energy Release (TKE) in 232 Th(n,f) with En = 2.59 - 87.31 MeV

    NASA Astrophysics Data System (ADS)

    King, Jonathan; Yanez, Ricardo; Barrett, Jonathan; Loveland, Walter; Tovesson, Fredrik; Fotiades, Nick; Lee, Hye Young

    2015-04-01

    Experimental results for the Total Kinetic Energy Release (TKE) of 232 Th(n,f) with En = 2.59 - 87.31 MeV will be presented. The experiment was performed at the 15R beamline at the Weapons Neutron Research(WNR) facility at LANL-LANSCE. WNR provides a white spectrum of neutrons peaking at 2 MeV and reaching up to 800 MeV, with neutron energies being deduced from measurements of the neutron time of flight (TOF). A thin-backed 232 ThF4 target of 2 cm diameter with a thorium areal density of 178.9 μg/cm2 was placed between two arrays of Hammamatsu PIN diodes (active area 4 cm2 each). The beam was collimated to 1 cm diameter. The target was placed 45 degrees off of the beam axis, with the detectors at 60 degrees and 120 degrees from the beam axis. Over 25,000 fission fragment coincidence events were recorded, allowing for sixteen energy bins between 2.59 and 87.31 MeV. We believe that this will be the most comprehensive published measurement of the TKE for 232 Th(n,f) with En = 2.59 - 87.31 MeV. This work was supported in part by the Director, Office of Energy Research, Division of Nuclear Physics of the Office of High Energy and Nuclear Physics of the USDoE under Grant DE-FG06-97ER41026. This work has benefited from the use of the Los Alamos Neutron Science Center at the Los Alamos National Laboratory. This facility is funded by the USDoE under DOE Contract No. DE-AC52-06NA25396.

  15. Comparison of the (p,xn) cross sections from /sup 238/U, /sup 235/U, and /sup 232/Th targets irradiated with 200-MeV protons

    SciTech Connect

    Chu, Y.Y.; Zhou, M.L.

    1982-01-01

    We have measured absolute cross sections for (p,xn) reactions (x ranges from 0 to 8) from /sup 238/U, /sup 235/U, and /sup 232/Th targets irradiated with 200-MeV protons at the Brookhaven AGS Linac injector. Chemical yields were determined by using /sup 239/Np and /sup 233/Pa as tracers. Yield patterns obtained in this work can be compared to the experimental results and theoretical calculations from earlier work, and they are consistent within the framework of intranuclear cascade followed by neutron evaporation and fission competition.

  16. Determination of environmental radioactivity (238U, 232Th and 40K) and indoor natural background radiation level in Chennai city (Tamilnadu State), India.

    PubMed

    Babai, K S; Poongothai, S; Punniyakotti, J

    2013-01-01

    An extensive study on the determination of the natural radioactivity ((238)U, (232)Th and (40)K) levels in soil samples of Chennai city, India has been undertaken and the results of the same are compared with the levels reported in other Indian cities as well as other parts of the world. The radioactivity content in the soil samples, the absorbed dose rate, annual effective dose equivalent, radium equivalent activity, internal and external hazard indices were calculated and compared with UNSCEAR 2000 recommended values. In addition to the above, mapping of indoor natural background gamma radiation levels has been made using thermo luminescent dosemeters throughout Chennai city and the same are reported.

  17. Quantification of transfer of (238)U, (226)Ra, (232)Th, (40)K and (137)Cs in mosses of a semi-natural ecosystem.

    PubMed

    Dragović, S; Mihailović, N; Gajić, B

    2010-02-01

    There is a lack of appropriate data on transfer of some radionuclides on many terrestrial biota groups. To expand the available data concentration ratios of (238)U, (226)Ra, (232)Th, (40)K and (137)Cs in mosses are presented in this paper. The relationship between concentration ratios of radionuclides and physicochemical characteristics of the underlying soil was also investigated. The data on concentration ratios obtained here will provide a useful addition to the currently used database of transfer parameters, particularly for natural radionuclides.

  18. 238U and 232Th series nuclides in groundwater from the J-13 well at the Nevada Test Site: Implications for ion retardation

    NASA Astrophysics Data System (ADS)

    Copenhaver, Sally A.; Krishnaswami, S.; Turekian, Karl K.; Shaw, Henry

    1992-07-01

    The activities of members of the 238U and 232Th decay chains have been determined in water from well J-13 at the Nevada Test Site near Yucca Mountain. Using 222Rn as a measure of recoil flux, adsorption (k1) and desorption (k2) rate constants for Ra and Pb have been determined. The ratio (k1/k2), defined as the dimensionless distribution coefficient, K, is 1.3 × 104 for Ra and 2.7 × 104 for Pb and is estimated to be about 104 for Th.

  19. Cost-based optimizations of power density and target-blanket modularity for {sup 232}Th/{sup 233}U-based ADEP

    SciTech Connect

    Krakowski, R.A.

    1995-07-01

    A cost-based parametric systems model is developed for an Accelerator-Driven Energy Production (ADEP) system based on a {sup 232}Th/{sup 233}U fuel cycle and a molten-salt (LiF/BeF{sub 2}/ThF{sub 3}) fluid-fuel primary system. Simplified neutron-balance, accelerator, reactor-core, chemical-processing, and balance-of-plant models are combined parametrically with a simplified costing model. The main focus of this model is to examine trade offs related to fission power density, reactor-core modularity, {sup 233}U breeding rate, and fission product transmutation capacity.

  20. Neutron inelastic-scattering cross sections of /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu and /sup 240/Pu. [LMFBR

    SciTech Connect

    Smith, A.B.; Guenther, P.T.

    1982-01-01

    Differential-neutron-emission cross sections of /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu and /sup 240/Pu are measured between approx. = 1.0 and 3.5 MeV with the angle and magnitude detail needed to provide angle-integrated emission cross sections to approx. < 3% accuracies. Emitted-neutron resolutions are quantitatively defined and vary from approx. = 0.1 to 0.35 MeV. The experimental results are corrected for fisson-neutron contributions to obtain pseudo-elastic-neutron-scattering cross sections which, together with the neutron total cross sections, define the non-elastic cross sections to within well specified energy resolutions. These results imply inelastic-neutron-scattering cross sections which are compared with comparable quantities derived from ENDF/B-V. Good general agreement is noted for /sup 232/Th, /sup 233/U, /sup 235/U and /sup 238/U inelastic-scattering values, poor agreement is observed for /sup 240/Pu, and a serious discrepancy exists in the case of /sup 239/Pu.

  1. Determination of (238)U, (232)Th and (40)K activity concentrations in riverbank soil along the Chao Phraya river basin in Thailand.

    PubMed

    Santawamaitre, T; Malain, D; Al-Sulaiti, H A; Bradley, D A; Matthews, M C; Regan, P H

    2014-12-01

    The activity concentrations of (238)U, (232)Th and (40)K in riverbank soil along the Chao Phraya river basin was determined through gamma-ray spectrometry measurements made using a hyper-pure germanium detector in a low background configuration. The ranges of activity concentrations of (238)U, (232)Th and (40)K were found to be 13.9 ↔ 76.8, 12.9 ↔ 142.9 and 178.4 ↔ 810.7 Bq kg(-1), respectively. The anthropogenic radionuclide, (137)Cs, was not observed in statistically significant amounts above the background level in the current study. The absorbed gamma dose rate in air at 1 m above the ground surface, the outdoor annual effective dose equivalent, the values of the radium equivalent activity and the external hazard index associated with all the soil samples in the present work were evaluated. The results indicate that the radiation hazard from primordial radionuclides in all soil samples from the area studied in this current work is not significant.

  2. Assessment of (226)Ra, (238)U, (232)Th, (137)Cs and (40)K activities from the northern coastline of Oman Sea (water and sediments).

    PubMed

    Darabi-Golestan, F; Hezarkhani, A; Zare, M R

    2017-02-27

    Water and sediment samples were collected from northern coast of Oman Sea covering from Goatr to Hormoz canyon seaport. Water and sediment quality assessment for naturally or anthropogenic radionuclides at Oman Sea as a main strategic golf for trade and transit, is an important issue. Correspondence analysis (CA) by R-mode analysis represents that sigma(T)-temperature-conductivity-O2 parameters are well-correlated with (226)Ra, (232)Th and (40)K. Accordingly Q-mode analysis revealed an indicator samples of ST13W for different radionuclides, ST03W for O2, and simultaneously ST34W-ST21W-ST08W-ST04W for sigma(T) parameters. The CA results overlapped with factor and cluster analysis results that explained 85.8% of total variance of water samples. Descriptive analysis of sediments indicates more significant variation than water samples. The (232)Th and (226)Ra generally showing that ST13D to ST25D sediments that restricted to Pi Bashk coastline are concentrated from (137)Cs and (40)K. By comparison with reference-values from Iran and other parts of the world, they are acceptable with respect to environmental and radioisotope hazards.

  3. Assessment of environmental (226)Ra, (232)Th and (40)K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia.

    PubMed

    Saleh, Muneer Aziz; Ramli, Ahmad Termizi; Alajerami, Yasser; Aliyu, Abubakar Sadiq

    2013-10-01

    Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h(-1) and 1.169 mSv y(-1), respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of (232)Th, (226)Ra and (40)K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg(-1) for (232)Th, 12 ± 1 to 968 ± 27 Bq kg(-1) for (226)Ra, and 12 ± 2 to 2450 ± 86 Bq kg(-1) for (40)K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg(-1) and 70 ± 20 to 4690 ± 90 Bq kg(-1), respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000.

  4. Vertical Profiles Of {sup 226}Ra, {sup 232}Th And {sup 40}K Activities In Rocks From The Irati Formation Of The Parana Sedimentary Basin, Southern Brazil

    SciTech Connect

    Ferreira, Ademar de O.; Bastos, Rodrigo O.; Appoloni, Carlos R.

    2008-08-07

    Naturally occurring radioisotopes are present in different concentrations in sedimentary rocks, reflecting the origin of the sediments, the depositional environment, and more recent events such as weathering and erosion. Using a high-resolution {gamma}-ray spectrometry methodology, sedimentary rocks were measured to assess the concentration activities of the natural radioisotopes. The surveyed rocks are from the Irati formation in the Parana sedimentary basin, which are exposed by an abandoned, open-pit limestone mine, in the city of Sapopema, southern Brazil. The exposed vertical profile is 5 m, and its stratigraphy is represented by an alternation of limestone and bituminous shale (layers being a few decimeters thick), and some millimeter rhythm layers with limestone and bituminous shale laminas. Eleven samples were collected along this profile, each of them dried in the open air during 48 hours, sieved through 4 mm mesh and sealed in cylindrical recipients. Measurements were accomplished using a 66% relative efficiency HPGE detector connected to a standard gamma ray spectrometry electronic chain. The detector efficiency in the range of 60 to 1800 keV was carried out with the certified IAEA-385 sediment sample. The Lower Limit of Detection (LLD) to the system is 2.40 Bq{center_dot}kg{sup -1} for {sup 226}Ra, 1.84 Bq{center_dot}kg{sup -1} for {sup 232}Th and 4.20 Bq{center_dot}kg{sup -1} for {sup 40}K. Activity concentrations were determined for {sup 226}Ra (from 16.22 to 151.55 Bq{center_dot}kg{sup -1}), {sup 232}Th (from 2.93 to 56.12 Bq{center_dot}kg{sup -1}) and {sup 40}K (from 38.45 to 644.63 Bq{center_dot}kg{sup -1}). The layers enriched with organic matter presented the higher values of activity. The measured concentrations of the natural radioisotopes were lower for limestone samples (average values and respective deviations were 22.81{+-}0.22 Bq{center_dot}kg{sup -1} for {sup 226}Ra, 4.21{+-}0.07 Bq{center_dot}kg{sup -1} for {sup 232}Th, and 50

  5. Measurement of activity concentrations of 40K, 226Ra and 232Th for assessment of radiation hazards from soils of the southwestern region of Nigeria.

    PubMed

    Ajayi, Oladele Samuel

    2009-08-01

    Activity concentrations of the selected radionuclides (40)K, (226)Ra and (232)Th were measured in surface soil samples collected from 38 cities in the southwest region of Nigeria by means of gamma spectroscopy with a high-purity germanium detector. Measured activity concentration values of (40)K varied from 34.9 +/- 4.4 to 1,358.6 +/- 28.5 Bq kg(-1) (given on a dry mass (DM) basis) with a mean value of 286.5 +/- 308.5 Bq kg(-1); that of (226)Ra varied from 9.3 +/- 3.7 to 198.1 +/- 13.8 Bq kg(-1) with a mean value of 54.5 Bq kg(-1) and a standard deviation of 38.7 Bq kg(-1), while that of (232)Th varied from 5.4 +/- 1.1 to 502.0 +/- 16.5 Bq kg(-1) with a mean value of 91.1 Bq kg(-1) and standard deviation of 100.9 Bq kg(-1). The mean activity concentration values obtained for (226)Ra and (232)Th are greater than the world average values reported by the United Nations Scientific Committee on Effects of Atomic Radiation for areas of normal background radiation. Radiological indices were estimated for the radiation/health hazards of the natural radioactivity of all soil samples. Estimated absorbed dose rates in air varied from 12.42 +/- 2.25 to 451.33 +/- 19.06 nGy h(-1), annual outdoor effective dose rates from 0.015 +/- 0.003 to 0.554 +/- 0.023 mSv year(-1), internal hazard index from 0.10 +/- 0.03 to 3.02 +/- 0.16, external hazard index from 0.07 +/- 0.01 to 2.60 +/- 0.11, representative level index from 0.19 +/- 0.03 to 6.84 +/- 0.29, activity index from 0.09 +/- 0.02 to 3.42 +/- 0.15, and radium equivalent activity from 26.95 +/- 5.04 to 963.15 +/- 41.87 Bq kg(-1). Only the mean value of the representative level index exceeds the limit for areas of normal background radiation. All other indices show mean values that are lower than the recommended limits.

  6. Dynamics of melt generation beneath mid-ocean ridge axes: Theoretical analysis based on [sup 238]U-[sup 230]Th-[sup 226]Ra and [sup 235]U-[sup 231]Pa disequilibria

    SciTech Connect

    Zhenwei Qin )

    1993-04-01

    Although slow melting favors the generation of basaltic melt from a mantle matrix with large radioactive disequilibrium between two actinide nuclides (McKenzie, 1985a), it results in long residence time in a magma chamber, during which the disequilibrium may be removed. An equilibrium melting model modified after McKenzie (1985a) is presented here which suggests that, for a given actinide parent-daughter pair, there exists a specific melting rate at which disequilibrium between these two nuclides reaches its maximum. This melting rate depends on the decay constant of the daughter nuclide concerned and the magma chamber volume scaled to that of its source. For a given scaled chamber size, large radioactive disequilibrium between two actinide nuclides in basalts will be observed if the melting rate is such that the residence time of the magma in the chamber is comparable to the mean life of the daughter nuclide. With a chamber size 1% in volume of the melting source, the melting rates at which maximum disequilibrium in basalts is obtained are 10[sup [minus]7], 2 [times] 10[sup [minus]7], and 3 [times] 10[sup [minus]6] y[sup [minus]1], respectively for [sup 238]U-[sup 230]Th, [sup 235]U-[sup 231]Pa, and [sup 230]Th-[sup 226]Ra. This implies that, while large disequilibrium between [sup 238]U-[sup 230]Th and between [sup 235]U-[sup 231]Pa may occur together, large [sup 230]Th-[sup 226]Ra disequilibrium will not coexist with large [sup 238]U-[sup 230]Th disequilibrium, consistent with some observations. The active mantle melting zone which supplies melt to a ridge axis is inferred to be only about 10 km thick and 50 km wide. The fraction of melt present in such a mantle source at any time is about 0.01 and 0.04, respectively, if melting rate is 10[sup [minus]7] and 10[sup [minus]6] y[sup [minus]1]. The corresponding residence time of the residual melt in the matrix is 10[sup 5] and 4 [times] 10[sup 4] y. 27 refs., 3 figs.

  7. Precise measurement and analysis of neutron transmission through /sup 232/Th. [6. 0 MeV to 0. 1 MeV

    SciTech Connect

    Olsen, D.K.; Ingle, R.W.; Portney, J.L.

    1980-01-01

    Three sets of transmission time spectra through up to eight samples of /sup 232/Th have been measured for neutron energies from 6.0 MeV to 0.1 MeV by use of a flight-time technique over 22- and 40-m path lengths, the ORELA pulsed neutron source, and a 1-mm-thick lithium glass detector. The resulting total cross section from 0.1 to 20.0 eV seems to be smaller than that contained in the ENDF/B-V evaluation. Least-squares analysis of the transmissions from 9 to 440 eV using a multilevel Breit-Wigner formalism results in neutron widths consistent with those previously reported. An average radiation width of 25.2 MeV is obtained for 19 low-energy s-wave resonances. 3 figures, 5 tables.

  8. Charge distribution of light mass fission products in the fast neutron induced fission of (232)Th, (238)U, (240)Pu and (244)Cm.

    PubMed

    Naik, Haladhara; Singh, Ram Janam; Dange, Shrikant Pandurang

    2017-09-01

    Fractional cumulative yields (FCY) of various light mass fission products in the fast neutron induced fission of (232)Th, (238)U, (240)Pu and (244)Cm have been determined by using the off-line γ-ray spectrometric technique. From present and literature data, width of isobaric charge distribution (σZ), the most probable charge (ZP) and the experimental charge polarization (∆ΖEXPT) as a function of fragment mass were deduced. The ∆ΖEXPT values from the present work for light mass chains and earlier work for heavy mass chains show oscillating nature due to nuclear structure effect. The ∆ΖMPE values based on minimum potential energy surface were theoretically calculated, which shows a systematic decrease trend with the approach of symmetric split due to the liquid drop behaviour of the fissioning nucleus. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Measurement of 232Th(n,5n γ) cross sections from 29 MeV to 42 MeV

    NASA Astrophysics Data System (ADS)

    Kerveno, M.; Nolte, R.; Baumann, P.; Dessagne, Ph.; Jericha, E.; Jokic, S.; Koning, A. J.; Lukic, S.; Meulders, J. P.; Nachab, A.; Pavlik, A.; Reginatto, M.; Rudolf, G.

    2014-10-01

    The excitation function of the reaction 232 Th( n, 5 nγ)228 Th from 29 to 42 MeV has been measured for the first time at the quasi-monoenergetic neutron beam of the UCL cyclotron CYCLONE employing the 7Li(p,n) source reaction. Taking advantage of the good energy resolution of the planar High-Purity Germanium (HPGe) detectors, prompt γ-ray spectroscopy was used to detect the γ-rays resulting from the decay of excited states of nuclei created by the (n, xn) reactions. The neutron beam was characterized by a combination of time of flight measurements carried out using a liquid scintillation detector and a 238U fission ionization chamber. Fluence measurements were performed using a proton recoil telescope. The results are compared with TALYS-1.4 code calculations.

  10. Porosity of the melting zone and variations in the solid mantle upwelling rate beneath Hawaii: Inferences from {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria

    SciTech Connect

    Sims, K.W.W.; DePaolo, D.J.; Murrell, M.T.; Baldridge, W.S.; Goldstein, S.; Clague, D.; Jull, M.

    1999-12-01

    Measurements of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in a suite of tholeiitic-to-basanitic lavas provide estimates of porosity, solid mantle upwelling rate and melt transport times beneath Hawaii. The observation that ({sup 230}Th/{sup 238}U) {gt} 1 indicates that garnet is required as a residual phase in the magma sources for all of the lavas. Both chromatographic porous flow and dynamic melting of a garnet peridotite source can adequately explain the combined U-Th-Ra and U-Pa data for these Hawaiian basalts. For chromatographic porous flow, the calculated maximum porosity in the melting zone ranges from 0.3--3% for tholeiites and 0.1--1% for alkali basalts and basanites, and solid mantle upwelling rates range from 40 to 100 cm/yr for tholeiites and from 1 to 3 cm/yr for basanites. For dynamic melting, the escape or threshold porosity is 0.5--2% for tholeiites and 0.1--0.8% for alkali basalts and basanites, and solid mantle upwelling rates range from 10 to 30 cm/yr for tholeiites and from 0.1 to 1 cm/yr for basanites. Assuming a constant melt productivity, calculated total melt fractions range from 15% for the tholeiitic basalts to 3% for alkali basalts and basanites.

  11. Transfer Rates of 238U and 232Th for E. globulus, A. mearnsii, H. filipendula and Hazardous Effects of the Usage of Medicinal Plants From Around Gold Mine Dump Environs

    PubMed Central

    Tshivhase, Victor M.; Njinga, Raymond L.; Mathuthu, Manny; Dlamini, Thulani C.

    2015-01-01

    Medicinal plant consumption can be a source of human exposure to radioactive elements such as 238U and 232Th, which can lead to internal radiation doses. The uptake of 238U and 232Th from soils to the leaf samples of three different medicinal plant species (Eucalyptus globulus, Acacia mearnsii and Hyparrhenia filipendula) from the purlieu of the Princess gold mine dump, an abandoned contaminated tailings storage site (TSS), located at longitude 27°55′00″E and latitude 26°09′30″S in Davidsonville (Roodepoort, west of Johannesburg, South Africa) was measured. This was done using ICP-MS spectrometry and substantial differences were observed in the soil-plant transfer factor (TF) values between these radionuclides. The plant species E. globulus exhibited the highest uptake of 238U, with an average TF of 3.97, while that of H. filipendula was 0.01 and the lowest TF of 0.15 × 10−2 was measured for A. mearnsii. However, in the case of 232Th, the highest average TF was observed for A. mearnsii (0.29), followed by E. globulus (0.10) and lowest was measured for H. filipendula (0.27 × 10−2). The ratio of TF average value i.e., 238U to 232Th in the soil-plant leaves was 38.05 for E. globulus, 0.01 for A. mearnsii and 4.38 for H. filipendula. PMID:26690462

  12. 238U series isotopes and 232Th in carbonates and black shales from the Lesser Himalaya: implications to dissolved uranium abundances in Ganga-Indus source waters.

    PubMed

    Singh, S K; Dalai, Tarun K; Krishnaswami, S

    2003-01-01

    238U and (232)Th concentrations and the extent of (238)U-(234)U-(230)Th radioactive equilibrium have been measured in a suite of Precambrian carbonates and black shales from the Lesser Himalaya. These measurements were made to determine their abundances in these deposits, their contributions to dissolved uranium budget of the headwaters of the Ganga and the Indus in the Himalaya and to assess the impact of weathering on (238)U-(234)U-(230)Th radioactive equilibrium in them. (238)U concentrations in Precambrian carbonates range from 0.06 to 2.07 microg g(-1). The 'mean' U/Ca in these carbonates is 2.9 ng U mg(-1) Ca. This ratio, coupled with the assumption that all Ca in the Ganga-Indus headwaters is of carbonate origin and that U and Ca behave conservatively in rivers after their release from carbonates, provides an upper limit on the U contribution from these carbonates, to be a few percent of dissolved uranium in rivers. There are, however, a few streams with low uranium concentrations, for which the carbonate contribution could be much higher. These results suggest that Precambrian carbonates make only minor contributions to the uranium budget of the Ganga-Indus headwaters in the Himalaya on a basin wide scale, however, they could be important for particular streams. Similar estimates of silicate contribution to uranium budget of these rivers using U/Na in silicates and Na* (Na corrected for cyclic and halite contributions) in river waters show that silicates can contribute significantly (approximately 40% on average) to their U balance. If, however, much of the uranium in these silicates is associated with weathering resistant minerals, then the estimated silicate uranium component would be upper limits. Uranium concentration in black shales averages about 37 microg g(-1). Based on this concentration, supply of U from at least approximately 50 mg of black shales per liter of river water is needed to balance the average river water U concentration, 1.7 microg L

  13. Determination of specific activity of (226)Ra, (232)Th and (40)K for assessment of radiation hazards from Turkish pumice samples.

    PubMed

    Turhan, Seref; Gündüz, Lüfullah

    2008-02-01

    The specific activity of (226)Ra, (232)Th and (40)K in 52 Turkish pumice samples collected from 11 geographical areas located in Central Anatolia, Eastern Anatolia, Mediterranean and Aegean regions was determined by gamma-ray spectrometry with a high-purity germanium (HPGe) detector. The specific activity of (226)Ra, (232)Th and (40)K ranged from 12.7+/-0.5 to 256.2+/-9.1Bqkg(-1) with a mean of 89.1+/-65.2Bqkg(-1), 12.3+/-1.0 to 237.9+/-12.2Bqkg(-1) with a mean of 87.0+/-61.4Bqkg(-1) and 300.1+/-5.5 to 1899.0+/-30.8Bqkg(-1) with a mean of 1211.9+/-419.8Bqkg(-1), respectively. Elemental concentrations were determined for U (from 1.0 to 20.7ppm with a mean of 7.2+/-5.3ppm), Th (from 3.0 to 58.6ppm with a mean of 21.4+/-15.1ppm) and K (from 1.0 to 6.1% with a mean of 3.9+/-1.3%). The radium equivalent activity (Ra(eq)), the activity index, the emanation coefficient, the (222)Rn mass exhalation rate, the indoor absorbed dose rate and the effective dose rate were estimated for the radiation hazard of the natural radioactivity in all samples. The calculated mean Ra(eq) value was 306.6+/-177.7Bqkg(-1) (54.6+/-5.5 to 737.6+/-49.0Bqkg(-1)) for all pumice samples. This value is lower than the recommended limit value of 370Bqkg(-1) for building raws and products. The emanation coefficient and the (222)Rn mass exhalation rate of all samples ranged from 29.4 to 42.9% with a mean of 36.2% and from 11.0 to 196.4microBqkg(-1)s(-1) with a mean of 73.5microBqkg(-1)s(-1), respectively. The mean indoor absorbed dose rate and the corresponding mean effective dose rate were 274.6+/-153.6nGyh(-1) (50.4-644.6nGyh(-1)) and 1.35+/-0.75mSvy(-1) (0.24-3.16mSvy(-1)), respectively. For all pumice samples the mean indoor absorbed dose rate is about three times higher than the population-weighted average of 84nGyh(-1), while the mean effective dose rate values except for PUM 05, PUM 06, PUM 10 and PUM 15 exceed the dose criterion of 1mSvy(-1).

  14. Vertical and horizontal distribution of radionuclides (232Th, 238U and 40K) in sediment from Manjung coastal water area Perak, Malaysia

    NASA Astrophysics Data System (ADS)

    Abdullah, Anisa; Hamzah, Zaini; Saat, Ahmad; Wood, Ab. Khalik

    2016-01-01

    Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides (232Th, 238U and 40K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (Igeo) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (Hex).

  15. Detection of inherited monazite in the Manaslu leucogranite by 208Pb/(232Th) ion microprobe dating: Crystallization age and tectonic implications

    NASA Astrophysics Data System (ADS)

    Harrison, T. Mark; McKeegan, K. D.; LeFort, P.

    1995-07-01

    Although leucogranites are among the least petrologically variable of all igneous rocks, ironically they are among the most difficult to reliably date. The High Himalayan leucogranites have been the subject of numerous geochronological investigations because of their interrelationship with the most significant tectonic features of that mountain belt. For a variety of reasons linked to the minimum melt composition of these leucogranites, these dating studies have not been entirely successful. We report results of a new ion microprobe dating method based on the decay of 232Th to 208Pb in monazite that has directly revealed the presence of inherited Pb in monazite from the Manalsu granite, casting doubt on its previously accepted age. Monazite ages obtained from this leucogranite yield two distinct populations, a large number of ages with a normal distribution and mean age of 22.4 ± 0.5 Ma (±2 S.E.) that we interpret to be the crystallization age, and a smaller inherited fraction with an age of ca. 600 Ma. Because formation of the granite is thought to be related to slip on the Main Central Thrust, both this date and a second less precise result from a structurally similar pluton near Mt. Everest indicate that the Main Central Thrust was active in the interval 24-22 Ma, but do not constrain its initiation. Together with crosscutting relationships, these data require that movement on the North Himalayan Fault occurred prior to 22 Ma at both locations.

  16. Calibration factors for determination of relativistic particle induced fission rates in natU, 235U, 232Th, natPb and 197Au foils

    NASA Astrophysics Data System (ADS)

    Hashemi-Nezhad, S. R.; Zhuk, Igor; Potapenko, A.; Kievets, M.; Krivopustov, M. I.

    2012-02-01

    Calibration factors w, for determination of fission rate in metallic foils of natU, 235U, 232Th, natPb and 197Au were determined for foils in contact with synthetic mica track detectors. Proton-induced fission at proton energies of 0.7 GeV and 1.5 GeV were used. Using our experimental results as well as those of the other authors, w for different foil-mica systems were determined. Two methods were used to calculate w, relative to the calibration factor for uranium-mica system, which has been obtained in a standard neutron field of energy 14.7 MeV. One of these methods requires the knowledge of the mean range of the fission fragments in the foils of interest and other method needs information on the values of the fission cross-sections at the required energies as well as the density of the tracks recorded in the track detectors in contact with the foil surfaces. The obtained w-values were compared with Monte Carlo calculations and good agreements were found. It is shown that a calibration factor obtained at low energy neutron induced fissions in uranium isotopes deviates only by less than 10% from those obtained at relativistic proton induced fissions.

  17. Large scale accelerator production of (225)Ac: Effective cross sections for 78-192MeV protons incident on (232)Th targets.

    PubMed

    Griswold, J R; Medvedev, D G; Engle, J W; Copping, R; Fitzsimmons, J M; Radchenko, V; Cooley, J C; Fassbender, M E; Denton, D L; Murphy, K E; Owens, A C; Birnbaum, E R; John, K D; Nortier, F M; Stracener, D W; Heilbronn, L H; Mausner, L F; Mirzadeh, S

    2016-12-01

    Actinium-225 and (213)Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of (225)Ac. The high-energy proton spallation reaction on natural thorium metal targets has been utilized to produce millicurie quantities of (225)Ac. The results of sixteen irradiation experiments of thorium metal at beam energies between 78 and 192MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridge National Laboratory (ORNL). Excitation functions for actinium and thorium isotopes, as well as for some of the fission products, are presented. The cross sections for production of (225)Ac range from 3.6 to 16.7mb in the incident proton energy range of 78-192MeV. Based on these data, production of curie quantities of (225)Ac is possible by irradiating a 5.0gcm(-2 232)Th target for 10 days in either BNL or LANL proton irradiation facilities.

  18. High precision 230Th/232Th and 234U/238U measurements using energyfiltered ICP magnetic sector multiple collector mass spectrometry

    NASA Astrophysics Data System (ADS)

    Luo, Xiaozhong; Rehkamper, Mark; Lee, Der-Chuen; Halliday, Alex N.

    1997-12-01

    We have developed new chemical and mass spectrometric techniques for the precise determination of 234U/238U and 230Th/232Th ratios in geological materials. The isotope ratio measurements were performed using an inductively coupled plasma double focusing magnetic sector multiple-collector mass spectrometer (MC-ICPMS) equipped with an additional energy filter. Following sample dissolution, U and Th are first separated from the rock matrix by a new and highly efficient column chromatographic procedure utilizing TRU-Spec resin. The strong affinity of U and Th for this material allows the use of extremely small ( < 0.5 ml resin) columns, even for the processing of silicate samples as large as ~5 g. Our new mass-spectrometric techniques permit precise corrections for mass discrimination and gain variation during analysis. As a consequence, the precision and external reproducibility of uranium and thorium isotopic analysis is improved by a factor of ~3-5 compared with previous results by conventional thermal ionization mass spectrometry (TIMS). A sensitivity of ~0.04% is routinely achieved for Th and this is comparable to the best values achieved by TIMS for large sample sizes. Recent instrumental improvements, however, have further increased our sensitivity by about a factor of five. Our Th and U isotope data for standard reference materials and other geological samples are in excellent agreement with previously published values from other laboratories, further highlighting the reliability and analytical capabilities of our new techniques.

  19. R-MATRIX ANALYSIS of 232Th NEUTRON TRANSMISSIONS and CAPTURE CROSS SECTIONS in the ENERGY RANGE THERMAL to 4 keV

    SciTech Connect

    Derrien, Herve; Leal, Luiz C; Larson, Nancy M

    2008-01-01

    Neutron resonance parameters of 232Th were obtained from the Reich-Moore SAMMY analysis of high-resolution neutron transmission measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) by Olsen in 1981, along with the high-resolution neutron capture measurements performed in 2005 at the Geel Linear Accelerator (GELINA, Belgium) by Schillebeeckx and at the n-TOF facility (CERN, Switzerland) by Aerts. The ORELA data were analyzed previously by Olsen with the Breit-Wigner multilevel code SIOB, and the results were used in the ENDF/B-VI evaluation. In the new analysis of the Olsen neutron transmissions by the modern computer code SAMMY, better accuracy is obtained for the resonance parameters by including in the experimental data base the recent experimental neutron capture data. The experimental data base and the method of analysis are described in the report. The neutron transmissions and the capture cross sections calculated with the resonance parameters are compared to the experimental values. A description is given of the statistical properties of the resonance parameters. The new evaluation results in a decrease in the capture resonance integral and improves the prediction of integral thermal benchmarks.

  20. Measurements of isomeric yield ratios of fission products from proton-induced fission on natU and 232Th via direct ion counting

    NASA Astrophysics Data System (ADS)

    Rakopoulos, Vasileios; Lantz, Mattias; Al-Adili, Ali; Gorelov, Dmitry; Jokinen, Ari; Kolhinen, Veli; Mattera, Andrea; Moore, Iain D.; Penttilä, Heikki; Prokofiev, Alexander V.; Solders, Andreas; Pomp, Stephan

    2017-09-01

    Independent isomeric yield ratios (IYR) of 81Ge, 96Y, 97Y, 97Nb, 128Sn and 130Sn have been determined in the 25 MeV proton-induced fission of natU and 232Th. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyväskylä. A direct ion counting measurement of the isomeric fission yield ratios was accomplished for the first time, registering the fission products in less than a second after their production. In addition, the IYRs of natU were measured by means of γ-spectroscopy in order to verify the consistency of the recently upgraded experimental setup. From the obtained results, indications of a dependence of the production rate on the fissioning system can be noticed. These data were compared with data available in the literature, whenever possible. Using the TALYS code and the experimentally obtained IYRs, we also deduced the average angular momentum of the fission fragments after scission.

  1. Vertical and horizontal distribution of radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) in sediment from Manjung coastal water area Perak, Malaysia

    SciTech Connect

    Abdullah, Anisa Hamzah, Zaini; Wood, Ab. Khalik; Saat, Ahmad

    2016-01-22

    Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (I{sub geo}) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (H{sub ex})

  2. Activity concentrations of 226Ra, 232Th, 40K and 137Cs radionuclides in Turkish medicinal herbs, their ingestion doses and cancer risks

    NASA Astrophysics Data System (ADS)

    Parmaksız, Aydın; Ağuş, Yusuf

    2014-11-01

    Twenty-two medicinal herb samples, each representing a distinct species, were collected from Turkish markets and measured by the gamma spectrometric method. The activity concentration of 226Ra in medicinal herbs was found in the range of minimum detectable activity (MDA) and 15.1 ± 2.2 Bqkg-1. The activity concentration of 232Th ranged from MDA values to 3.5 ± 0.8 Bqkg-1. The activity concentration of 40K varied between 50.0 ± 16.8 and 1311.5 ± 57.3 Bqkg-1. All 137Cs activity concentrations of medicinal herbs were found to have lower than MDA values. The bone surface dose, lower large intestine and colon doses were found to be 182.9, 18.8 and 18.7 µSvy-1, respectively. The highest committed effective dose originated from the annual ingestion of 1 kg medicinal herb was calculated notably low as 9.0 µSv. The cancer risk of ingestion of medicinal herbs was found to be small enough to be neglected. The selected Turkish medicinal herbs are considered safe for human consumption.

  3. Measurement of 238U and 232Th in Petrol, Gas-oil and Lubricant Samples by Using Nuclear Track Detectors and Resulting Radiation Doses to the Skin of Mechanic Workers.

    PubMed

    Misdaq, M A; Chaouqi, A; Ouguidi, J; Touti, R; Mortassim, A

    2015-10-01

    Workers in repair shops of vehicles (cars, buses, truck, etc.) clean carburetors, check fuel distribution, and perform oil changes and greasing. To explore the exposure pathway of (238)U and (232)Th and its decay products to the skin of mechanic workers, these radionuclides were measured inside petrol, gas-oil, and lubricant material samples by means of CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs), and corresponding annual committed equivalent doses to skin were determined. The maximum total equivalent effective dose to skin due to the (238)U and (232)Th series from the application of different petrol, gas-oil, and lubricant samples by mechanic workers was found equal to 1.2 mSv y(-1) cm(-2).

  4. Study of secondary neutron interactions with 232Th, 129I, and 127I nuclei with the uranium assembly “QUINTA” at 2, 4, and 8GeV deuteron beams of the JINR Nuclotron accelerator

    DOE PAGES

    Adam, J.; Chilap, V. V.; Furman, V. I.; ...

    2015-11-04

    The natural uranium assembly, “QUINTA”, was irradiated with 2, 4, and 8 GeV deuterons. The 232Th, 127I, and 129I samples have been exposed to secondary neutrons produced in the assembly at a 20-cm radial distance from the deuteron beam axis. The spectra of gamma rays emitted by the activated 232Th, 127I, and 129I samples have been analyzed and several tens of product nuclei have been identified. For each of those products, neutron-induced reaction rates have been determined. The transmutation power for the 129I samples is estimated. Furthermore, experimental results were compared to those calculated with well-known stochastic and deterministic codes.

  5. Allanite from the El Muerto Pegmatite, Oaxaca, Mexico: A Potential New Standard for 232Th-208Pb Dating by LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Price, J.; Crowley, J. L.; Solari, L.; Prol-Ledesma, R.

    2012-12-01

    Allanite dating may be important to studies addressing tectonomagmatic evolution, provenance of monocyclic sediment, and mineral weathering. Obtaining accurate allanite ages by SIMS has been challenging and time-consuming due to the mineral's extreme chemical variability which often prevents finding adequately matrix-matched standards. Isotopic measurements by LA-ICP-MS minimize the need for standards of nearly identical composition to the unknown allanite being analyzed, and it is done relatively rapidly. Dating by LA-ICP-MS requires high quality standards for isotopic fractionation corrections. However, readily accessible and well characterized allanite standards are scarce. We investigated gemstone allanite from the El Muerto pegmatite, Oaxaca, Mexico, as a potential new geochronology standard for 232Th-208Pb allanite dating by LA-ICP-MS. Compositional homogeneity was thoroughly investigated by scanning and backscatter electron microscopy, cathodoluminescence, quantitative and qualitative energy dispersive x-ray spectroscopy, electron microprobe, and LA-ICP-MS. The possibility of metamictization was investigated by extensive X-ray diffraction analyses. The El Muerto allanite was U-Pb dated by ID-TIMS, with common Pb ratios determined from cogenetic K-feldspar by ID-TIMS and LA-MC-ICP-MS. Future work includes Th-Pb dating by ID-TIMS. The samples investigated are homogeneous with respect to major and trace elements. Major element compositional results are generally in agreement with published values, and no metamictization was identified despite the allanite being nearly 1 Ga. The only limitation of the El Muerto allanite is that it contains small, generally <100 μm, scarce inclusions of quartz, calciothorite, albite, calcite, and biotite. However, these grains are easily recognized and avoided during LA-ICP-MS analyses. Based on these results, the El Muerto allanite has the potential to serve as a standard for LA-ICP-MS dating.

  6. Radionuclides (40K, 232Th and 238U) and Heavy Metals (Cr, Ni, Cu, Zn, As and Pb) Distribution Assessment at Renggam Landfill, Simpang Renggam, Johor, Malaysia

    NASA Astrophysics Data System (ADS)

    Zaidi, E.; FahrulRazi, MJ; Azhar, ATS; Hazreek, ZAM; Shakila, A.; Norshuhaila, MS; Omeje, M.

    2017-08-01

    The assessment of radioactivity levels and the distribution of heavy metals in soil samples at CEP Farm landfill, Renggam in Johor State was to determine the activity concentrations of naturally occurring radionuclides and heavy metal concentrations of this landfill. The background radiation was monitored to estimate the exposure level. The activity concentrations of radionuclides in soil samples were determined using HPGe gamma ray spectroscopy whereas the heavy metal concentration was measured using X-RF analysis. The mean exposure rate at the landfill site was 36.2±2.4 μR hr-1 and the annual effective dose rate at the landfill site was 3.19 ± 0.22 mSv yr-1. However, residential area has lower mean exposure dose rate of about 16.33±0.72 μR hr-1 and has an annual effective dose rate of 1.43±0.06 mSv yr-1 compared to landfill sites. The mean activity concentration of 40K, 238U and 232Th at landfill site were 239.95±15.89 Bq kg-1, 20.90±2.49 Bq kg-1 and 40.61±4.59 Bq kg-1, respectively. For heavy metal compositions, Cr, Ni and Cu have mean concentration of 232±10 ppm, 23±2 ppm, and 46±19 ppm, respectively. Whereas, Zn has concentration of 64±9 ppm and concentration of 12±1 ppm and 71±2 ppm was estimated for As and Pb respectively. The higher activity concentration of 40K down the slope through leaching process whereas the higher activity level of 238U content at the landfill site may be attributed to the soil disruption to local equilibrium.

  7. A precise 232Th-208Pb chronology of fine-grained monazite: Age of the Bayan Obo REE-Fe-Nb ore deposit, China

    USGS Publications Warehouse

    Wang, Jingyuan; Tatsumoto, M.; Li, X.; Premo, W.R.; Chao, E.C.T.

    1994-01-01

    We have obtained precise Th-Pb internal isochron ages on monazite and bastnaesite for the world's largest known rare earth elements (REE)-Fe-Nb ore deposit, the Bayan Obo of Inner Mongolia, China. The monazite samples, collected from the carbonate-hosted ore zone, contain extremely small amounts of uranium (less than 10 ppm) but up to 0.7% ThO2. Previous estimates of the age of mineralization ranged from 1.8 to 0.255 Ga. Magnetic fractions of monazite and bastnaesite samples (<60-??m size) showed large ranges in 232Th 204Pb values (900-400,000) and provided precise Th-Pb internal isochron ages for paragenetic monazite mineralization ranging from 555 to 398 Ma within a few percent error (0.8% for two samples). These results are the first indication that REE mineralization within the giant Bayan Obo ore deposit occurred over a long period of time. The initial lead isotopic compositions (low 206Pb 204Pb and high 208Pb 204Pb) and large negative ??{lunate}Nd values for Bayan Obo ore minerals indicate that the main source(s) for the ores was the lower crust which was depleted in uranium, but enriched in thorium and light rare earth elements for a long period of time. Zircon from a quartz monzonite, located 50 km south of the ore complex and thought to be related to Caledonian subduction, gave an age of 451 Ma, within the range of monazite ages. Textural relations together with the mineral ages favor an epigenetic rather than a syngenetic origin for the orebodies. REE mineralization started around 555 Ma (disseminated monazite in the West, the Main, and south of the East Orebody), but the main mineralization (banded ores) was related to the Caledonian subduction event ca. 474-400 Ma. ?? 1994.

  8. 187Re - 232Th - 238U nuclear geochronometry: constraining magmatism in East-Antarctica and the break-up of Gondwana

    NASA Astrophysics Data System (ADS)

    Roller, Goetz

    2017-04-01

    187Re - 232Th - 238U nuclear geochronometry is a new dating method for astronomy, earth and planetary sciences [1-4]. Nucleogeochronometric Rhenium-Osmium two-point-isochron (TPI) ages are calculated using a nuclear geochronometer as one data point in a two-point-isochron diagram [5-7]. The IVREA chronometer, for example, is one of five terrestrial nuclear geochronometers identified so far [8]. Here, it is used to constrain the magmatism of the Ferrar flood basalt province, which has been related to continental rifting and the break-up of Gondwana in the Jurassic.TPI ages for seven (basaltic) andesite whole rock samples from the Prince Albert Mountains (Victoria Land, Antarctica) are calculated. An isochron age of 172 ± 5 Ma (187Os/188Osi = 0.194 ± 0.023) has previously been published for these rocks [9]. Initial TPI 187Os/188Osi ratios show only minor scatter between 187Os/188Osi = 0.2149 ± 0.0064 and 187Os/188Osi = 0.22231 ± 0.00080, in agreement with the enigmatic, suprachondritic 187Os/188Osi = 0.194 ± 0.023 from the isochron [9]. TPI ages for the Mount Joyce samples range from 125.4 ± 9.9 Ma to 139 ± 17 Ma and thus constrain the youngest magmatic event(s) in the Transantarctic Mountains. For the Thumb Point basalt, a TPI age of 219 ± 81 Ma is calculated. Despite of its large uncertainty, the age itself is in agreement with the Triassic 224 Ma and 240 Ma events reported from North Patagonia [10]. The TPI age of 186.1 ± 8.1 Ma from the Ricker Hill basalt can be clearly distinguished from the Mount Murray TPI age of 158 ± 14 Ma, while at Brimstone Peak two TPI age groups of 155 ± 14 Ma and 175.3 ± 3.1 Ma are observed. From this it may be concluded that the seven TPI ages indicate episodic magmatic activity in East-Antarctica between 125 Ma and 219 Ma, leading to the break-up of Gondwana. This picture is consistent with the geochronology of the Antarctic Peninsula, Patagonia, the Karoo and the Ferrar mafic rocks [10]. Thus, besides constraining

  9. Investigation of (235)U, (226)Ra, (232)Th, (40)K, (137)Cs, and heavy metal concentrations in Anzali international wetland using high-resolution gamma-ray spectrometry and atomic absorption spectroscopy.

    PubMed

    Zare, Mohammad Reza; Kamali, Mahdi; Fallahi Kapourchali, Maryam; Bagheri, Hashem; Khoram Bagheri, Mahdi; Abedini, Ali; Pakzad, Hamid Reza

    2016-02-01

    Measurements of natural radioactivity levels and heavy metals in sediment and soil samples of the Anzali international wetland were carried out by two HPGe-gamma ray spectrometry and atomic absorption spectroscopy techniques. The concentrations of (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs in sediment samples ranged between 1.05 ± 0.51-5.81 ± 0.61, 18.06 ± 0.63-33.36 ± .0.34, 17.57 ± 0.38-45.84 ± 6.23, 371.88 ± 6.36-652.28 ± 11.60, and 0.43 ± 0.06-63.35 ± 0.94 Bq/kg, while in the soil samples they vary between 2.36-5.97, 22.71-38.37, 29.27-42.89, 472.66-533, and 1.05-9.60 Bq/kg for (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs, respectively. Present results are compared with the available literature data and also with the world average values. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose. Heavy metal concentrations were found to decrease in order as Fe > Mn > Sr > Zn > Cu > Cr > Ni > Pb > Co > Cd. These measurements will serve as background reference levels for the Anzali wetland.

  10. 235U, 238U, 232Th, 40K and 137Cs activity concentrations in marine sediments along the northern coast of Oman Sea using high-resolution gamma-ray spectrometry.

    PubMed

    Zare, Mohammad Reza; Mostajaboddavati, Mojtaba; Kamali, Mahdi; Abdi, Mohammad Reza; Mortazavi, Mohammad Seddigh

    2012-09-01

    The natural radioactivity levels in sediment samples of the northern coast of Oman Sea, covering the coastal strip from Hormoz canyon to Goatr seaport, as the first time has been determined. The results of measurements will serve as background reference level for Oman Sea coastlines. Sediments from 36 coastal and near shore locations were collected for analysis. Analysis on the collected samples were carried out to determine (235)U, (238)U, (232)Th, (40)K and (137)Cs using two high purity germanium detectors with 38.5% and 55% relative efficiencies. The concentration of (235)U, (238)U, (232)Th, (40)K and (137)Cs in sediment samples ranged between 1.01 and 2.87 Bq/kg, 11.83 and 22.68 Bq/kg, 10.7 and 25.02 Bq/kg, 222.89 and 535.07 Bq/kg and 0.14 and 2.8 Bq/kg, respectively. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Characterization of bauxite residue (red mud) for (235)U, (238)U, (232)Th and (40)K using neutron activation analysis and the radiation dose levels as modeled by MCNP.

    PubMed

    Landsberger, S; Sharp, A; Wang, S; Pontikes, Y; Tkaczyk, A H

    2017-07-01

    This study employs thermal and epithermal neutron activation analysis (NAA) to quantitatively and specifically determine absorption dose rates to various body parts from uranium, thorium and potassium. Specifically, a case study of bauxite residue (red mud) from an industrial facility was used to demonstrate the feasibility of the NAA approach for radiological safety assessment, using small sample sizes to ascertain the activities of (235)U, (238)U, (232)Th and (40)K. This proof-of-concept was shown to produce reliable results and a similar approach could be used for quantitative assessment of other samples with possible radiological significance. (238)U and (232)Th were determined by epithermal and thermal neutron activation analysis, respectively. (235)U was determined based on the known isotopic ratio of (238)U/(235)U. (40)K was also determined using epithermal neutron activation analysis to measure total potassium content and then subtracting its isotopic contribution. Furthermore, the work demonstrates the application of Monte Carlo Neutral-Particle (MCNP) simulations to estimate the radiation dose from large quantities of red mud, to assure the safety of humans and the surrounding environment. Phantoms were employed to observe the dose distribution throughout the human body demonstrating radiation effects on each individual organ. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Decay of {sup 246}Bk* formed in similar entrance channel reactions of {sup 11}B+{sup 235}U and {sup 14}N+{sup 232}Th at low energies using the dynamical cluster-decay model

    SciTech Connect

    Singh, BirBikram; Sharma, Manoj K.; Gupta, Raj K.

    2008-05-15

    The decay of the {sup 246}Bk* nucleus, formed in entrance channel reactions {sup 11}B+{sup 235}U and {sup 14}N+{sup 232}Th at different incident energies, is studied by using the dynamical cluster-decay model (DCM) extended to include the deformations and orientations of nuclei. The main decay mode here is fission. The other (weaker) decay channels are the light particles evaporation (A{<=}4) and intermediate mass fragments (5{<=}A{<=}20). All decay products are calculated as emissions of preformed clusters through the interaction barriers. The calculated fission cross sections {sigma}{sub fiss}, taken as a sum of the energetically favored symmetric and near symmetric fragments (A{sub CN}/2{+-}7 and A=106-110 plus complementary fragments) show an excellent agreement with experimental data at all experimental incident c.m. energies for both reactions, except for the top three energies in the case of the {sup 11}B+{sup 235}U reaction. The disagreement between the DCM calculations and data at higher incident c.m. energies for the {sup 11}B+{sup 235}U entrance channel is associated with the presence of additional effects of noncompound, quasifission (qf) components, in contradiction with the measured anisotropy effects which indicate the other entrance channel {sup 14}N+{sup 232}Th to contain the noncompound nucleus contribution. The prediction of two fission windows, the symmetric fission (SF) and near symmetric or heavy mass fragments (HMFs), suggests the presence of a fine structure of fission fragments, which also need an experimental verification. The only parameter of the model is the neck length parameter {delta}R whose value is shown to depend strongly on limiting angular momentum, which in turn depends on the use of sticking or nonsticking moment of inertia for angular momentum effects.

  13. Plant uptake of (238)U, (235)U, (232)Th, (226)Ra, (210)Pb and (40)K from a coal ash and slag disposal site and control soil under field conditions: A preliminary study.

    PubMed

    Skoko, Božena; Marović, Gordana; Babić, Dinko; Šoštarić, Marko; Jukić, Mirela

    2017-06-01

    The aim of this study was to investigate the uptake of (238)U, (235)U, (232)Th, (226)Ra, (210)Pb and (40)K by plants that grow on a coal ash and slag disposal site known for its higher content of naturally occurring radionuclides. Plant species that were sampled are common for the Mediterranean flora and can be divided as follows: grasses & herbs, shrubs and trees. To compare the activity concentrations and the resultant concentration ratios of the disposal site with those in natural conditions, we used control data specific for the research area, obtained for plants growing on untreated natural soil. Radionuclide activity concentrations were determined by high resolution gamma-ray spectrometry. Media parameters (pH, electrical conductivity and organic matter content) were also analysed. We confirmed significantly higher activity concentrations of (238)U, (235)U, (226)Ra and (210)Pb in ash and slag compared to control soil. However, a significant increase in the radionuclide activity concentration in the disposal site's vegetation was observed only for (226)Ra. On the contrary, a significantly smaller activity concentration of (40)K in ash and slag had no impact on its activity concentration in plant samples. The calculated plant uptake of (238)U, (235)U, (226)Ra and (210)Pb is significantly smaller in comparison with the uptake at the control site, while it is vice versa for (40)K. No significant difference was observed between the disposal site and the control site's plant uptake of (232)Th. These results can be the foundation for further radioecological assessment of this disposal site but also, globally, they can contribute to a better understanding of nature and long-term management of such disposal sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Ingestion dose from 238U, 232Th, 226Ra, 40K and 137Cs in cereals, pulses and drinking water to adult population in a high background radiation area, Odisha, India.

    PubMed

    Lenka, Pradyumna; Sahoo, S K; Mohapatra, S; Patra, A C; Dubey, J S; Vidyasagar, D; Tripathi, R M; Puranik, V D

    2013-03-01

    A natural high background radiation area is located in Chhatrapur, Odisha in the eastern part of India. The inhabitants of this area are exposed to external radiation levels higher than the global average background values, due to the presence of uranium, thorium and its decay products in the monazite sands bearing placer deposits in its beaches. The concentrations of (232)Th, (238)U, (226)Ra, (40)K and (137)Cs were determined in cereals (rice and wheat), pulses and drinking water consumed by the population residing around this region and the corresponding annual ingestion dose was calculated. The annual ingestion doses from cereals, pulses and drinking water varied in the range of 109.4-936.8, 10.2-307.5 and 0.5-2.8 µSv y(-1), respectively. The estimated total annual average effective dose due to the ingestion of these radionuclides in cereals, pulses and drinking water was 530 µSv y(-1). The ingestion dose from cereals was the highest mainly due to a high consumption rate. The highest contribution of dose was found to be from (226)Ra for cereals and drinking water and (40)K was the major dose contributor from the intake of pulses. The contribution of man-made radionuclide (137)Cs to the total dose was found to be minimum. (226)Ra was found to be the largest contributor to ingestion dose from all sources.

  15. Neutron scattering cross sections for /sup 232/Th and /sup 238/U inferred from proton scattering and charge exchange measurements. [7 MeV, 26 and 27 MeV

    SciTech Connect

    Hansen, L.F.; Grimes, S.M.; Pohl, B.A.; Poppe, C.H.; Wong, C.

    1980-01-01

    Differential cross sections for the (p,n) reactions to the isobaric analog states (IAS) of /sup 232/Th and /sup 238/U targets were measured at 26 and 27 MeV. The analysis of the data was done in conjunction with the proton elastic and inelastic (2/sup +/, 4/sup +/, 6/sup +/) differential cross sections measured at 26 MeV. Because collective effects are important in this mass region, deformed coupled-channels calculations were carried out for the simultaneous analysis of the proton and neutron outgoing channels. The sensitivity of the calculations was studied with respect to the optical model parameters used in the calculations, the shape of the nuclear charge distribution, the type of coupling scheme assumed among the levels, the magnitude of the deformation parameters, and the magnitude of the isovector potentials, V/sub 1/ and W/sub 1/. A Lane model-consistent analysis of the data was used to infer optical potential parameters for 6- to 7-MeV neutrons. The neutron elastic differential cross sections obtained from these calculations are compared with measurements available in the literature, and with results obtained using neutron parameters from global sets reported at these energies. 7 figures, 3 tables.

  16. Biogeography in 231Pa/230Th ratios and a balanced 231Pa budget for the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher T.; Anderson, Robert F.; Fleisher, Martin Q.; Serno, Sascha; Winckler, Gisela; Gersonde, Rainer

    2014-04-01

    The ratio of unsupported protactinium-231 to thorium-230 in marine sediments, (Pa/Th)xs, is potentially sensitive to several processes of oceanographic and climatological interest: deep ocean circulation, marine biological productivity (as it relates to total particle flux) and particle composition (specifically, biogenic opal and authigenic Mn). In order to attribute variations in (Pa/Th)xs observed in sediment records to changes in specific processes through time, a better understanding of the chemical cycling of these elements in the modern ocean is necessary. To this end, a survey was undertaken of (Pa/Th)xs in surface sediments from the subarctic Pacific (SO202-INOPEX expedition) in combination with a Pacific-wide compilation of published data. Throughout the Pacific, (Pa/Th)xs is robustly correlated with the opal content of sediments. In the North and equatorial Pacific, simultaneous positive correlations with productivity indicators suggest that boundary scavenging and opal scavenging combine to enhance the removal of Pa in the eastern equatorial Pacific and subarctic Pacific. Deep ocean water mass ageing (>3.5 km) associated with the Pacific overturning appears to play a secondary role in determining the basin scale distribution of (Pa/Th)xs. A basin-wide extrapolation of Pa removal is performed which suggests that the Pacific Pa budget is nearly in balance. We hypothesize that through time (Pa/Th)xs distributions in the Pacific could define the evolving boundaries of contrasting biogeographic provinces in the North Pacific, while the influence of hydrothermal scavenging of Pa potentially confounds this approach in the South Pacific.

  17. Characterization of actinide physics specimens for the US/UK joint experiment in the Dounreay Prototype Fast Reactor

    SciTech Connect

    Walker, R.L.; Botts, J.L.; Cooper, J.H.; Adair, H.L.; Bigelow, J.E.; Raman, S.

    1983-10-01

    The United States and the United Kingdom are engaged in a joint research program in which samples of the higher actinides are irradiated in the Dounreay Prototype Fast Reactor in Scotland. The purpose of the porogram is (1) to study the materials behavior of selected higher actinide fuels and (2) to determine the integral cross sections of a wide variety of the higher actinide isotopes. Samples of the actinides are incorporated in fuel pins inserted in the core. For the fuel study, the actinides selected are /sup 241/Am and /sup 244/Cm in the form of Am/sub 2/O/sub 3/, Cm/sub 2/O/sub 3/, and Am/sub 6/Cm(RE)/sub 7/O/sub 21/, where (RE) represents a mixture of lanthanides. For the cross-section determinations, the samples are milligram quantities of actinide oxides of /sup 248/Cm, /sup 246/Cm, /sup 244/Cm, /sup 243/Cm, /sup 243/Am, /sup 241/Am, /sup 244/Pu, /sup 242/Pu, /sup 241/Pu, /sup 240/Pu, /sup 239/Pu, /sup 238/Pu, /sup 237/Np, /sup 238/U, /sup 236/U, /sup 235/U, /sup 234/U, /sup 233/U, /sup 232/Th, /sup 230/Th, and /sup 231/Pa encapsulated in vanadium. Coincident with the irradiations, neutron flux and energy spectral measurements are made with vanadium-encapsulated dosimeter materials located within the same fuel pins.

  18. Preparation of actinide specimens for the US/UK joint experiment in the Dounreay Prototype Fast Reactor

    SciTech Connect

    Quinby, T C; Adair, H L; Kobisk, E H

    1982-05-01

    A joint research program involving the United States and the United Kingdom was initiated about four years ago for the purpose of studying the fuel behavior of higher actinides using in-core irradiation in the fast reactor at Dounreay, Scotland. Simultaneously, determination of integral cross sections of a wide variety of higher actinide isotopes (physics specimens) was proposed. Coincidental neutron flux and energy spectral measurements were to be made using vanadium encapsulated dosimetry materials in the immediate region of the fuel pellets and physics samples. The higher actinide samples chosen for the fuel study were /sup 241/Am and /sup 244/Cm in the forms of Am/sub 2/O/sub 3/, Cm/sub 2/O/sub 3/, and Am/sub 6/Cm(RE)/sub 7/O/sub 21/, where (RE) represents a mixture of lanthanides. Milligram quantities of actinide oxides of /sup 248/Cm, /sup 246/Cm, /sup 244/Cm, /sup 243/Cm, /sup 243/Am, /sup 241/Am, /sup 244/Pu, /sup 242/Pu, /sup 241/Pu, /sup 240/Pu, /sup 239/Pu, /sup 238/Pu, /sup 237/Np, /sup 238/U, /sup 236/U, /sup 235/U, /sup 234/U, /sup 233/U, /sup 232/Th, /sup 230/Th, and /sup 231/Pa were encapsulated to obtain nuclear cross section and reaction rate data for these materials.

  19. Measurements of plutonium, 237Np, and 137Cs in the BCR 482 lichen reference material

    DOE PAGES

    Lavelle, Kevin B.; Miller, Jeffrey L.; Hanson, Susan K.; ...

    2015-10-01

    Select anthropogenic radionuclides were measured in lichen reference material, BCR 482. This material was originally collected in Axalp, Switzerland in 1991 and is composed of the epiphytic lichen Pseudevernia furfuracea. Samples from three separate bottles of BCR 482 were analyzed for uranium, neptunium, and plutonium isotopes by inductively coupled plasma mass spectrometry (ICP-MS) and analyzed for cesium-137 by gamma-ray spectrometry. The isotopic composition of the radionuclides measured in BCR 482 suggests contributions from both global fallout resulting from historical nuclear weapons testing and more volatile materials released following the Chernobyl accident.

  20. Mössbauer effect studies on organometallic237Np-compounds

    NASA Astrophysics Data System (ADS)

    Adrian, G.; Appel, H.; Bohlander, R.; Haffner, H.; Kanellakopulos, B.

    1988-02-01

    A series of organometallic compounds of tetravalent Neptunium was studied by Moessbauer methods. Three of them will be presented here. Their molecular structure is close to C3v symmetry. The data were parameterised on the basis of an anisotropic paramagnetic relaxation model and will be interpreted for each individual compound. In general it can be stated that distortions from axially symmetric hyperfine parameters were observed, no magnetic ordering occured at all temperatures above 1.5 K and anisotropic relaxation frequencies had to be introduced to fit the spectra.

  1. Post-Irradiation Examination of 237Np Targets for 238Pu Production

    SciTech Connect

    Morris, Robert Noel; Baldwin, Charles A; Hobbs, Randy W; Schmidlin, Joshua E

    2015-01-01

    Oak Ridge National Laboratory is recovering the US 238Pu production capability and the first step in the process has been to evaluate the performance of a 237Np target cermet pellet encased in an aluminum clad. The process proceeded in 3 steps; the first step was to irradiate capsules of single pellets composed of NpO2 and aluminum power to examine their shrinkage and gas release. These pellets were formed by compressing sintered NpO2 and aluminum powder in a die at high pressure followed by sintering in a vacuum furnace. Three temperatures were chosen for sintering the solution precipitated NpO2 power used for pellet fabrication. The second step was to irradiate partial targets composed of 8 pellets in a semi-prototypical arrangement at the two best performing sintering temperatures to determine which temperature gave a pellet that performed the best under the actual planned irradiation conditions. The third step was to irradiate ~50 pellets in an actual target configuration at design irradiation conditions to assess pellet shrinkage and gas release, target heat transfer, and dimensional stability. The higher sintering temperature appeared to offer the best performance after one cycle of irradiation by having the least shrinkage, thus keeping the heat transfer gap between the pellets and clad small minimizing the pellet operating temperature. The final result of the testing was a target that can meet the initial production goals, satisfy the reactor safety requirements, and can be fabricated in production quantities. The current focus of the program is to verify that the target can be remotely dissembled, the pellets dissolved, and the 238Pu recovered. Tests are being conducted to examine these concerns and to compare results to code predictions. Once the performance of the full length targets has been quantified, the pellet 237Np loading will be revisited to determine if it can be increased to increase 238Pu production.

  2. MOX and MOX with 237Np/241Am Inert Fission Gas Generation Comparison in ATR

    SciTech Connect

    G. S. Chang; M. Robel; W. J. Carmack; D. J. Utterbeck

    2006-06-01

    The treatment of spent fuel produced in nuclear power generation is one of the most important issues to both the nuclear community and the general public. One of the viable options to long-term geological disposal of spent fuel is to extract plutonium, minor actinides (MA), and potentially long-lived fission products from the spent fuel and transmute them into short-lived or stable radionuclides in currently operating light-water reactors (LWR), thus reducing the radiological toxicity of the nuclear waste stream. One of the challenges is to demonstrate that the burnup-dependent characteristic differences between Reactor-Grade Mixed Oxide (RG-MOX) fuel and RG-MOX fuel with MA Np-237 and Am 241 are minimal, particularly, the inert gas generation rate, such that the commercial MOX fuel experience base is applicable. Under the Advanced Fuel Cycle Initiative (AFCI), developmental fuel specimens in experimental assembly LWR-2 are being tested in the northwest (NW) I-24 irradiation position of the Advanced Test Reactor (ATR). The experiment uses MOX fuel test hardware, and contains capsules with MOX fuel consisting of mixed oxide manufactured fuel using reactor grade plutonium (RG-Pu) and mixed oxide manufactured fuel using RG-Pu with added Np/Am. This study will compare the fuel neutronics depletion characteristics of Case-1 RG-MOX and Case-2 RG-MOX with Np/Am.

  3. Measurement and calculation of high-actinide burnup in the prototype fast reactor

    SciTech Connect

    Broadhead, B.L.; Raman, S.; Dickens, J.K. )

    1991-01-01

    An agreement was signed in May 1979 as a part of a long-term cooperative program between the United Kingdom and the US under the liquid-metal fast breeder reactor agreement of 1976. This agreement included an experiment to carry out irradiations of physics specimens of fissile and fertile actinides to improve our knowledge of basic nuclear physics phenomena. Three fuel pins were prepared by the US to contain the actinide physics samples; two of these pins were irradiated at the Dounreay prototype fast reactor (PFR) for a total irradiation of 63 full-power days. The third pin has only recently been removed from the PFT, following an irradiation of > 500 full-power days. Each pin houses 35 capsules containing milligram quantities of actinide oxides of {sup 231}Pa, {sup 230}Th, {sup 232}Th, {sup 233}U, {sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U, {sup 237}Np, {sup 238}Pu, {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, {sup 242}Pu, {sup 244}Pu, {sup 241}Am, {sup 243}Am, {sup 243}Cm, {sup 244}Cm, {sup 246}Cm, and {sup 248}Cm. Following the return of the first fuel pin (FP-1) to the United States in May 1984, the actinide samples were prepared for studies of fission product yields, isotopics, and material concentrations. The measurements were repeated for the second fuel pin (FP-2) to remedy several problems encountered in the processing of the FP-1 pin. A brief description of the measured and calculated {sup 137}Cs yields for both FP-1 and FP-2 are included in this paper.

  4. Controls on 231Pa/230Th in the Indian Ocean: Circulation or Productivity?

    NASA Astrophysics Data System (ADS)

    Thomas, A. L.; Henderson, G. M.; McCave, N.

    2004-12-01

    (231Paxs/230Thxs)0 ratios in marine sediments are a potential proxy of palaeoproductivity and/or past ocean circulation. Studies in the Atlantic have demonstrated the particular potential of this proxy to assess the rate of past circulation AƒAøAøâ_sA¬Aøâ,¬Å" an important environmental variable which is otherwise difficult to reconstruct {[1, 2]}. In this study, we present new water-column and sediment data from the western Indian Ocean to improve understanding of the controls on (231Paxs/230Thxs)0 and test the use of this proxy. The Indian Ocean differs from the Atlantic because deep waters forming in the Southern Ocean and transported into the basin have high rather than low Pa and Th concentrations [3]. The ability to reconstruct past rates of flow into the Indian Ocean would be a powerful new use of Pa/Th, but no data presently exist to test this application. Water samples (10 litre), surface sediments, and a 5.5m Kasten core were collected on the Charles Darwin cruise CD154 from the area East of Madagascar. The down-core record, from10°S extends to 150 ka, and is coupled with a stable isotope stratigraphy and a sortable silt record. Water and sediment samples were analysed for isotopes of Pa, Th and U on a Nu Instruments MC-ICP-MS. The water-column dataset (26 samples) indicate that Pa concentrations are high in NADW transported into the Indian Ocean from the Atlantic, while opal scavenging has lowered Pa concentrations in deeper water masses. Sedimentary 230Th data indicate that there has been significant sediment focusing and that sediment mass fluxes are low. Preliminary sedimentary Pa/Th data show little relation to the sortable silt record. Ongoing Pa/Th and Ba data will complete this downcore record and allow comparison of a Pa/Th record with independent proxies of current speed and productivity in the same core. [1] E.F. Yu, et al, Nature 379, 689-694, 1996. [2] J.F. McManus, et al, Nature 428, 834-837, 2004. [3] M. M. Rutgers van der Loeff, and G. W. Berger. Deep-Sea Research Part I: Oceanographic Research Papers. 40(2): 339-357, 1993.

  5. Rapid determination of (237)Np and plutonium isotopes in urine by inductively-coupled plasma mass spectrometry and alpha spectrometry.

    PubMed

    Maxwell, Sherrod L; Culligan, Brian K; Jones, Vernon D; Nichols, Sheldon T; Noyes, Gary W; Bernard, Maureen A

    2011-08-01

    A new rapid separation method was developed for the measurement of plutonium and neptunium in urine samples by inductively-coupled plasma mass spectrometry (ICP-MS) and/or alpha spectrometry with enhanced uranium removal. This method allows separation and preconcentration of plutonium and neptunium in urine samples using stacked extraction chromatography cartridges and vacuum box flow rates to facilitate rapid separations. There is an increasing need to develop faster analytical methods for emergency response samples. There is also enormous benefit to having rapid bioassay methods in the event that a nuclear worker has an uptake (puncture wound, etc.) to assess the magnitude of the uptake and guide efforts to mitigate dose (e.g., tissue excision and chelation therapy). This new method focuses only on the rapid separation of plutonium and neptunium with enhanced removal of uranium. For ICP-MS, purified solutions must have low salt content and low concentration of uranium due to spectral interference of (238)U(1)H(+) on m/z 239. Uranium removal using this method is enhanced by loading plutonium and neptunium initially onto TEVA resin, then moving plutonium to DGA resin where additional purification from uranium is performed with a decontamination factor of almost 1×10(5). If UTEVA resin is added to the separation scheme, a decontamination factor of ~3 × 10(6) can be achieved.

  6. Proton-induced fission of actinides at energies 26.5 and 62.9 MeV—Theoretical interpretation

    NASA Astrophysics Data System (ADS)

    Demetriou, P.; Keutgen, Th.; Prieels, R.; El Masri, Y.

    2011-10-01

    Fission properties of proton-induced fission on 232Th, 237Np, 238U, 239Pu and 241Am targets, measured at the Louvain-la-Neuve cyclotron facility at proton energies of 26.5 and 62.9 MeV, are compared with the predictions of the state-of-the-art nuclear reaction code TALYS. The sensitivity of the calculations to the input parameters of the code and possible improvements are discussed.

  7. FFTF (FAST FLUX TEST FACILITY) REACTOR CHARACTERIZATION PROGRAM ABSOLUTE FISSION RATE MEASUREMENTS

    SciTech Connect

    FULLER JL; GILLIAM DM; GRUNDL JA; RAWLINS JA; DAUGHTRY JW

    1981-05-01

    Absolute fission rate measurements using modified National Bureau of Standards fission chambers were performed in the Fast Flux Test Facility at two core locations for isotopic deposits of {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu. Monitor chamber results at a third location were analyzed to support other experiments involving passive dosimeter fission rate determinations.

  8. FFTF (Fast Flux Test Facility) Reactor Characterization Program: Absolute Fission-rate Measurements

    SciTech Connect

    Fuller, J.L.; Gilliam, D.M.; Grundl, J.A.; Rawlins, J.A.; Daughtry, J.W.

    1981-05-01

    Absolute fission rate measurements using modified National Bureau of Standards fission chambers were performed in the Fast Flux Test Facility at two core locations for isotopic deposits of {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu. Monitor chamber results at a third location were analyzed to support other experiments involving passive dosimeter fission rate determinations.

  9. Modelling the role of marine particle on large scale 231Pa, 230Th, Iron and Aluminium distributions

    NASA Astrophysics Data System (ADS)

    Dutay, J.-C.; Tagliabue, A.; Kriest, I.; van Hulten, M. M. P.

    2015-04-01

    The distribution of trace elements in the ocean is governed by the combined effects of various processes, and by exchanges with external sources. Modelling these represents an opportunity to better understand and quantify the mechanisms that regulate the oceanic tracer cycles. Observations collected during the GEOTRACES program provide an opportunity to improve our knowledge regarding processes that should be considered in biogeochemical models to adequately represent the distributions of trace elements in the ocean. Here we present a synthesis about the state of the art for simulating selected trace elements in biogeochemical models: Protactinium, Thorium, Iron and Aluminium. In this contribution we pay particular attention on the role of particles in the cycling of these tracers and how they may provide additional constraints on the transfer of matter in the ocean.

  10. Reanalysis of the Gas-cooled fast reactor experiments at the zero power facility Proteus - Spectral indices

    NASA Astrophysics Data System (ADS)

    Perret, G.; Pattupara, R. M.; Girardin, G.; Chawla, R.

    2013-03-01

    PROTEUS is a zero power reactor at the Paul Scherrer Institute which has been employed during the 1970's to study experimentally the physics of the gas-cooled fast reactor. Reaction rate distributions, flux spectrum and reactivity effects have been measured in several configurations featuring PuO2/UO2 fuel, absorbers, large iron shields, and thorium oxide and thorium metal fuel either distributed quasihomogeneously in the reference PuO2/UO2 lattice or introduced in the form of radial and axial blanket zones. This papers focus on the spectral indices - including fission and capture in 232Th and 237Np - measured in the reference PuO2/UO2 lattices and their predictions with an MCNPX model specially developed for the PROTEUS-GCFR core. Predictions were obtained with JEFF-3.1 and -3.11, ENDF/B-VII.0 and VII.1, and JENDL-3.3 and -4.0. A general good agreement was demonstrated. The ratio of 232Th fission to 239Pu fission, however, was under-predicted by 8.7±2.1% and 6.5±2.1% using ENDF/B-VII.0 and VII.1, respectively. Finally, the capture rates in 237Np tended to be underpredicted by the JEFF and JENDL libraries, although the new cross section in JEFF-3.1.1 slightly improved the 237Np capture to 239Pu fission results (3.4±2.4%).

  11. Incorporation of neptunium(V) and iodate into a uranyl phosphate: implications for mitigating the release of 237Np and 129I in repositories.

    PubMed

    Wu, Shijun; Chen, Fanrong; Simonetti, Antonio; Albrecht-Schmitt, Thomas E

    2010-04-15

    The simultaneous incorporation of IO3(-) and NpO2+ into Ba3(UO2)2(HPO4)2(PO4)2 (BaUP), which serves as a model for uranyl alteration phases, was investigated. LA-ICP-MS data demonstrate that the incorporation of both of these species is significantly enhanced when they are present together. The most probable explanation is that charge balance is obtained by the coupled substitutions of NpO2+ <--> UO2(2+) and IO3(-) <--> HPO4(2-). According to the LA-ICP-MS results, in the absence of iodate as much as 2.91 +/- 0.14 to 3.44 +/- 0.25% of the uranium in BaUP can be replaced by neptunium. When iodate is present in the reaction, the amount of uranium substitution by neptunium increases to 6.05 +/- 0.65% to 7.93 +/- 0.83%. The net increase for neptunium is 116 +/- 0.30% to 225 +/- 0.25%. Similarly, in the absence of NpO2+, iodate incorporation into BaUP reaches an I/U level of 0.0021 +/- 0.0004 to 0.0038 +/- 0.0005; whereas in its presence there is an increase to as much as 100 +/- 0.11% to 0.0042 +/- 0.0008.

  12. Neutronics Simulations of 237Np Targets to Support Safety-Basis and 238Pu Production Assessment Efforts at the High Flux Isotope Reactor

    SciTech Connect

    Chandler, David; Ellis, Ronald James

    2015-01-01

    Fueled by two highly enriched uranium-bearing fuel elements surrounded by a large concentric ring of beryllium reflector, the High Flux Isotope Reactor (HFIR) provides one of the highest neutron fluxes in the world and is used to produce unique isotopes like plutonium-238. The National Aeronautics and Space Administration use radioisotope thermoelectric generators powered by 238Pu for deep-space missions. As part of the US Department of Energy s task to reestablish the domestic production of 238Pu, a technology demonstration sub-project has been initiated to establish a new 238Pu supply chain. HFIR safety-basis neutronics calculations are being performed to ensure the target irradiations have no adverse impacts on reactor performance and to calculate data required as input to follow-on thermal-structural, thermal-hydraulic and radionuclide/dose analyses. Plutonium-238 production assessments are being performed to estimate the amount of 238Pu that can be produced in HFIR s permanent beryllium reflector. It is estimated that a total of 0.96 1.12 kg 238Pu (~1.28 1.49 kg PuO2 at 85% 238Pu/Pu purity) could be produced per year in HFIR s permanent beryllium reflector irradiation facilities if they are all utilized.

  13. Transmutation of 129I, 237Np, 238Pu, 239Pu and 241Am Using Neutrons Produced in Target-Blanket System ``Energy & Transmutation'' Bombarded by Relativistic Protons

    NASA Astrophysics Data System (ADS)

    Adam, J.; Katovsky, K.; Balabekyan, A.; Solnyshkin, A. A.; Kalinnikov, V. G.; Stegailov, V. I.; Tsoupko-Sitnikov, V. M.; Stetsenko, S. G.; Krivopustov, M. I.; Pronskikh, V. S.; Vladimirova, N. M.; Kumawat, H.

    2005-05-01

    Target-blanket facility "Energy & Transmutation" was irradiated by a 2 GeV proton beam extracted from the Nuclotron Accelerator at the Joint Institute for Nuclear Research in Dubna, Russia. Radioactive samples made from iodine, neptunium, plutonium and americium were irradiated by spallation neutrons produced in the "E&T" facility. Transmutation reaction yields (residual nuclei production yields) have been determined using methods of γ-spectroscopy. The energy spectrum of the neutron field has been studied by using a set of threshold detectors.

  14. Protactinium and isotopes of thorium in metalliferous sediments from the Bauer depression

    SciTech Connect

    Arslanov, K.A.; Kuznetsov, V.Yu.; Lokshin, N.V.; Pospelov, Yu.N.

    1989-01-01

    Results are presented of a study of the vertical distribution of /sup 238/U, /sup 234/U, /sup 232/Th, /sup 230/Th, and /sup 231/Pa isotopes in a column of metalliferous sediments from the Bauer depression (southeastern part of the Pacific Ocean). On the basis of the obtained data a hypothesis is formulated concerning the authigenic production of /sup 230/Th and /sup 231/Pa in these deposits, i.e, the similarity of the physicochemical behavior of /sup 230/Th and /sup 231/Pa found in pelagic sediments is found in these specific sediments also. We present arguments in favor of the identical behavior of these radionuclides in the marine environment. With the help of the ionium method of dating marine sediments, the average rate of sedimentation of the investigated column of metalliferous sediments from the Bauer depression was calculated.

  15. On the role of energy separated in fission process, excitation energy and reaction channels effects in the isomeric ratios of fission product 135Xe in photofission of actinide elements

    NASA Astrophysics Data System (ADS)

    Thiep, Tran Duc; An, Truong Thi; Cuong, Phan Viet; Vinh, Nguyen The; Mishinski, G. V.; Zhemenik, V. I.

    2016-07-01

    In this work we present the isomeric ratio of fission product 135Xe in the photo-fission of actinide elements 232Th, 233U and 237Np induced by end-point bremsstrahlung energies of 13.5, 23.5 and 25.0 MeV which were determined by the method of inert gaseous flow. The data were analyzed, discussed and compared with the similar data from literature to examine the role of energy separated in fission process, excitation energy and reaction channels effects.

  16. Separation of actinides using capillary extraction chromatography-inductively coupled plasma mass spectrometry.

    PubMed

    Peterson, Dominic S; Montoya, Velma M

    2009-08-01

    Trace levels of actinides have been separated on capillary extraction chromatography columns. Detection of the actinides was achieved using an inductively coupled plasma mass spectrometer, which was coupled with the extraction chromatography system. In this study, we compare 30-cm long, 4.6 mm i.d. columns to capillary columns (750 microm i.d.) with lengths from 30 cm up to 150 cm. The columns that were tested were packed with TRU resin. We were able to separate a mixture of five actinides ((232)Th, (238)U, (237)Np, (239)Pu, and (241)Am). This work has application to rapid bioassay as well as automated separations of actinide materials.

  17. Gastrointestinal absorption of protactinium, uranium, and neptunium in the hamster

    SciTech Connect

    Harrison, J.D.; Stather, J.W.

    1981-10-01

    The gastrointestinal absorption of protactinium, uranium, and neptunium in adult hamsters was measured. The actinide preparations were administered intragastrically and animals were kept 2 to 4 weeks prior to the radiochemical analysis of selected tissue samples. Total absorption was estimated using data for the distribution of the actinides after intravenous injection in soluble form. The values obtained were 3.9 and 0.22% for /sup 231/Pa citrate and /sup 231/Pa fluoride, respectively; 0.77 and 0.11% for /sup 233/U (uranyl) nitrate and /sup 233/U dioxide, respectively; and 0.06 and 0.05% for /sup 237/Np citrate and /sup 237/Np nitrate, respectively. The absorption factors recommended by the International Commission on Radiological Protection for use in calculating annual limits on intake for occupationally exposed workers are: 0.1% for all compounds of Pa; 5 and 0.2% for soluble hexavalent and relatively insoluble tetravalent forms of U, respectively; and 1.0% for all chemical forms of Np. The experimental basis for these values is discussed.

  18. Indirect (n,γ) cross sections of thorium cycle nuclei using the surrogate method

    NASA Astrophysics Data System (ADS)

    Wilson, J. N.; Gunsing, F.; Bernstein, L. A.; Bürger, A.; Görgen, A.; Guttormsen, M.; Larsen, A.-C.; Mansouri, P.; Renstrøm, T.; Rose, S. J.; Semchenkov, A.; Siem, S.; Syed, N. U. H.; Toft, H. K.; Wiedeking, M.; Wiborg-Hagen, T.

    2012-03-01

    Indirect neutron capture (n,γ) cross sections have been extracted for the key thorium cycle nuclei 232Th, 231Pa, and 230Th using the surrogate reaction method. Final nucleus γ-decay probabilities were measured between the neutron binding energy and around 1 MeV above it using the 232Th(d,p)233Th, 232Th(3He,t)232Pa, and 232Th(3He,α)231Th reactions in experiments with the CACTUS γ-detector array and Silicon Ring charged-particle detectors at the Oslo Cyclotron Laboratory. Because the neutron capture cross section for 232Th is already well known from direct measurements a comparison with these results provides a stringent test of the applicability of the surrogate method in the actinide region for indirect (n,γ) cross-section measurements. In addition, a new technique for correcting measured γ-ray decay probabilities below the neutron emission energy threshold is proposed and used. We find good agreement between indirect and direct (n,γ) cross-section measurements in the range 500 keV-1 MeV, but large discrepancies outside this range. Explanations for the observed differences are proposed.

  19. Fission Product Yields from 232Th, 238U, and 235U Using 14 MeV Neutrons

    NASA Astrophysics Data System (ADS)

    Pierson, B. D.; Greenwood, L. R.; Flaska, M.; Pozzi, S. A.

    2017-01-01

    Neutron-induced fission yield studies using deuterium-tritium fusion-produced 14 MeV neutrons have not yet directly measured fission yields from fission products with half-lives on the order of seconds (far from the line of nuclear stability). Fundamental data of this nature are important for improving and validating the current models of the nuclear fission process. Cyclic neutron activation analysis (CNAA) was performed on three actinide targets-thorium-oxide, depleted uranium metal, and highly enriched uranium metal-at the University of Michigan's Neutron Science Laboratory (UM-NSL) using a pneumatic system and Thermo-Scientific D711 accelerator-based fusion neutron generator. This was done to measure the fission yields of short-lived fission products and to examine the differences between the delayed fission product signatures of the three actinides. The measured data were compared against previously published results for 89Kr, -90, and -92 and 138Xe, -139, and -140. The average percent deviation of the measured values from the Evaluated Nuclear Data Files VII.1 (ENDF/B-VII.1) for thorium, depleted-uranium, and highly-enriched uranium were -10.2%, 4.5%, and -12.9%, respectively. In addition to the measurements of the six known fission products, 23 new fission yield measurements from 84As to 146La are presented.

  20. 238U, 232Th profiling and U-series isotope analysis of fossil teeth by laser ablation-ICPMS

    NASA Astrophysics Data System (ADS)

    Eggins, Stephen; Grün, Rainer; Pike, Alistair W. G.; Shelley, Michael; Taylor, Lois

    2003-05-01

    U and Th concentration profiles in fossil hominid and faunal teeth have been measured by laser ablation ICPMS. These profiles record diverse modes of U and Th uptake, particularly within enamel, that can be broadly related to the state of sample preservation. Observed U profiles are in general inconsistent with existing diffusion-adsorption models developed for U-uptake in bone and teeth. Where the models appear applicable, calculated diffusion rates are several orders of magnitude smaller than previous estimates. Laser ablation ICPMS offers a means of rapidly characterizing U and Th distributions in the enamel and dentine components of teeth as a precursor to ESR and U-series dating. In particular, it should allow the identification of teeth (and also bone) samples that have simple U-uptake histories and are amenable to precise dating by time-consuming and expensive Th-U and Pa-U TIMS techniques. We also demonstrated the use of laser ablation ICPMS to measure U-series isotopes in dentine and enamel samples with relatively high U concentrations (>20 ppm). These results, obtained using a quadrupole ICPMS, illustrate significant promise for in situ U-series isotope analysis, particularly when combined with the greater sensitivity and multi-collection capabilities of new sector ICPMS instrumentation. The latter may permit precise isotope ratio measurements on samples containing only a few ppm of U.

  1. Level Densities in the actinide region and indirect n,y cross section measurements using the surrogate method

    NASA Astrophysics Data System (ADS)

    Wilson, J. N.; Gunsing, F.; Bernstein, L.; Bürger, A.; Görgen, A.; Thompson, I. J.; Guttormssen, M.; Larsen, A.-C.; Mansouri, P.; Renstrøm, T.; Rose, S. J.; Siem, S.; Wiedeking, M.; Wiborg, T.

    2012-02-01

    Results from a program of measurements of level densities and gamma ray strength functions in the actinide region are presented. Experiments at the Oslo cyclotron involving the Cactus/Siri detectors and 232Th(d,x) and 232Th(3He,x) reactions were carried out to help answer the question of which level density model is the most appropriate for actinide nuclei, since it will have an impact on cross section calculations important for reactor physics simulations. A new technique for extracting level densities and gamma ray strength functions from particle-gamma coincidence data is proposed and results from the development of this technique are presented. In addition, simultaneous measurements of compound nuclear gamma decay probabilities have been performed for the key thorium cycle nuclei 233Th, 231Th and 232Pa up to around 1MeV above the neutron binding energy and have enabled extraction of indirect neutron induced capture cross sections for the 232Th, 231Pa and 230Th nuclei using the surrogate reaction method. Since the neutron capture cross section for 232Th is already well known from direct measurements a comparison provides a stringent test of the applicability of the surrogate technique in the actinide region.

  2. Certified reference material for radionuclides in fish flesh sample IAEA-414 (mixed fish from the Irish Sea and North Sea).

    PubMed

    Pham, M K; Sanchez-Cabeza, J A; Povinec, P P; Arnold, D; Benmansour, M; Bojanowski, R; Carvalho, F P; Kim, C K; Esposito, M; Gastaud, J; Gascó, C L; Ham, G J; Hegde, A G; Holm, E; Jaskierowicz, D; Kanisch, G; Llaurado, M; La Rosa, J; Lee, S-H; Liong Wee Kwong, L; Le Petit, G; Maruo, Y; Nielsen, S P; Oh, J-S; Oregioni, B; Palomares, J; Pettersson, H B L; Rulik, P; Ryan, T P; Sato, K; Schikowski, J; Skwarzec, B; Smedley, P A; Tarján, S; Vajda, N; Wyse, E

    2006-01-01

    A certified reference material (CRM) for radionuclides in fish sample IAEA-414 (mixed fish from the Irish Sea and North Seas) is described and the results of the certification process are presented. Nine radionuclides (40K, 137Cs, 232Th, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) were certified for this material. Information on massic activities with 95% confidence intervals is given for six other radionuclides (90Sr, 210Pb(210Po), 226Ra, 239Pu, 240Pu 241Pu). Less frequently reported radionuclides (99Tc, 129I, 228Th, 230Th and 237Np) and information on some activity and mass ratios are also included. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in fish sample, for the development and validation of analytical methods and for training purposes. The material is available from IAEA, Vienna, in 100 g units.

  3. AN INTEGRAL REACTOR PHYSICS EXPERIMENT TO INFER ACTINIDE CAPTURE CROSS-SECTIONS FROM THORIUM TO CALIFORNIUM WITH ACCELERATOR MASS SPECTROMETRY

    SciTech Connect

    G. Youinou; M. Salvatores; M. Paul; R. Pardo; G. Palmiotti; F. Kondev; G. Imel

    2010-04-01

    The principle of the proposed experiment is to irradiate very pure actinide samples in the Advanced Test Reactor (ATR) at INL and, after a given time, determine the amount of the different transmutation products. The determination of the nuclide densities before and after neutron irradiation will allow inference of effective neutron capture cross-sections. This approach has been used in the past and the novelty of this experiment is that the atom densities of the different transmutation products will be determined using the Accelerator Mass Spectroscopy (AMS) technique at the ATLAS facility located at ANL. It is currently planned to irradiate the following isotopes: 232Th, 235U, 236U, 238U, 237Np, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, 241Am, 243Am and 248Cm.

  4. MANTRA: An Integral Reactor Physics Experiment to Infer Actinide Capture Cross-sections from Thorium to Californium with Accelerator Mass Spectrometry

    SciTech Connect

    G. Youinou; C. McGrath; G. Imel; M. Paul; R. Pardo; F. Kondev; M. Salvatores; G. Palmiotti

    2011-08-01

    The principle of the proposed experiment is to irradiate very pure actinide samples in the Advanced Test Reactor at INL and, after a given time, determine the amount of the different transmutation products. The determination of the nuclide densities before and after neutron irradiation will allow inference of effective neutron capture cross-sections. This approach has been used in the past and the novelty of this experiment is that the atom densities of the different transmutation products will be determined using the Accelerator Mass Spectrometry technique at the ATLAS facility located at ANL. It is currently planned to irradiate the following isotopes: 232Th, 235U, 236U, 238U, 237Np, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, 241Am, 243Am, 244Cm and 248Cm.

  5. Method for detecting and correcting for isotope burn-in during long-term neutron dosimetry exposure

    DOEpatents

    Ruddy, Francis H.

    1988-01-01

    A method is described for detecting and correcting for isotope burn-in during-long term neutron dosimetry exposure. In one embodiment, duplicate pairs of solid state track recorder fissionable deposits are used, including a first, fissionable deposit of lower mass to quantify the number of fissions occuring during the exposure, and a second deposit of higher mass to quantify the number of atoms of for instance .sup.239 Pu by alpha counting. In a second embodiment, only one solid state track recorder fissionable deposit is used and the resulting higher track densities are counted with a scanning electron microscope. This method is also applicable to other burn-in interferences, e.g., .sup.233 U in .sup.232 Th or .sup.238 Pu in .sup.237 Np.

  6. Cross sections and barriers for nuclear fission induced by high-energy nucleons

    SciTech Connect

    Grudzevich, O. T.; Yavshits, S. G.

    2013-03-15

    The cross sections for the fission of {sup 232}Th, {sup 235,238}U, {sup 237}Np, and {sup 239}Pu target nuclei that was induced by 20- to 1000-MeV neutrons and protons were calculated. The respective calculations were based on the multiconfiguration-fission (MCFx) model, which was used to describe three basic stages of the interaction of high-energy nucleons with nuclei: direct processes (intranuclear cascade), equilibration of the emerging compound system, and the decay of the compound nucleus (statistical model). Fission barriers were calculated within the microscopic approach for isotopic chains formed by 15 to 20 nuclei of the required elements. The calculated fission cross sections were compared with available experimental data. It was shown that the input data set and the theoretical model used made it possible to predict satisfactorily cross section for nuclear fission induced by 20- to 1000-MeV nucleons.

  7. Separation of actinides using capillary extraction chromatography-inductively coupled plasma mass spectrometry

    SciTech Connect

    Peterson, Dominic S

    2008-01-01

    Trace levels of actinides have been separated on extraction chromatography columns. Detection of the actinides was achieved using an inductively coupled plasma mass spectrometer (ICP-MS), which was coupled with the extraction chromatography system. In this study we compare 30 cm long, 4.6 mm ID columns to capillary columns (750 {micro}m ID) with lengths from 30 cm up to 150 cm. The columns that were tested were packed with TRU resin. We were able to separate a mixture of five actinides ({sup 232}Th, {sup 238}U, {sup 237}Np, {sup 239}pU, {sup 241}Am). This work has application to rapid bioassay as well as for automated separations of actinide materials.

  8. Actinide integral measurements in the CFRMF and integral tests for ENDF/B-V

    SciTech Connect

    Anderl, R.A.

    1982-01-01

    Integral capture and/or fission rates have been reported earlier for several actinides irradiated in the fast neutron field of the Coupled Fast Reactivity Measurements Facility (CFRMF). These nuclides include /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, /sup 240/Pu, /sup 242/Pu, /sup 241/Am and /sup 243/Am. This paper forucses on the utilization of these integral data for testing the respective cross sections on ENDF/B-V. Integral cross sections derived from the measured reaction rates are tabulated. Results are presented for cross-section data testing which includes integral testing based on a comparison of calculated and measured integral cross sections and testing based on least-squares-adjustment analyses.

  9. Modelling the effect of boundary scavenging on Thorium and Protactinium profiles in the ocean

    NASA Astrophysics Data System (ADS)

    Roy-Barman, M.

    2009-07-01

    The "boundary scavenging" box model is a cornerstone of our understanding of the particle-reactive radionuclide fluxes between the open ocean and the ocean margins. However, it does not describe the radionuclide profiles in the water column. Here, I present the transport-reaction equations for radionuclides transported vertically by reversible scavenging on settling particles and laterally by horizontal currents between the margin and the open ocean. Analytical solutions of these equations are compared with existing data. In the Pacific Ocean, the model produces "almost" linear 230Th profiles (as observed in the data) despite lateral transport. However, omitting lateral transport biased the 230Th based particle flux estimates by as much as 50%. 231Pa profiles are well reproduced in the whole water column of the Pacific Margin and from the surface down to 3000 m in the Pacific subtropical gyre. Enhanced bottom scavenging or inflow of 231Pa-poor equatorial water may account for the model-data discrepancy below 3000 m. The lithogenic 232Th is modelled using the same transport parameters as 230Th but a different source function. The main source of 232Th scavenged in the open Pacific is advection from the ocean margin, whereas a net flux of 230Th produced in the open Pacific is advected and scavenged at the margin, illustrating boundary exchange. In the Arctic Ocean, the model reproduces 230Th measured profiles that the uni-dimensional scavenging model or the scavenging-ventilation model failed to explain. Moreover, if lateral transport is ignored, the 230Th based particle settling speed may by underestimated by a factor 4 at the Arctic Ocean margin. The very low scavenging rate in the open Arctic Ocean combined with the enhanced scavenging at the margin accounts for the lack of high 231Pa/230Th ratio in arctic sediments.

  10. Modelling the effect of boundary scavenging on Thorium and Protactinium profiles in the ocean

    NASA Astrophysics Data System (ADS)

    Roy-Barman, M.

    2009-12-01

    The "boundary scavenging" box model is a cornerstone of our understanding of the particle-reactive radionuclide fluxes between the open ocean and the ocean margins. However, it does not describe the radionuclide profiles in the water column. Here, I present the transport-reaction equations for radionuclides transported vertically by reversible scavenging on settling particles and laterally by horizontal currents between the margin and the open ocean. Analytical solutions of these equations are compared with existing data. In the Pacific Ocean, the model produces "almost" linear 230Th profiles (as observed in the data) despite lateral transport. However, omitting lateral transport biaises the 230Th based particle flux estimates by as much as 50%. 231Pa profiles are well reproduced in the whole water column of the Pacific Margin and from the surface down to 3000 m in the Pacific subtropical gyre. Enhanced bottom scavenging or inflow of 231Pa-poor equatorial water may account for the model-data discrepancy below 3000 m. The lithogenic 232Th is modelled using the same transport parameters as 230Th but a different source function. The main source of the 232Th scavenged in the open Pacific is advection from the ocean margin, whereas a net flux of 230Th produced in the open Pacific is advected and scavenged at the margin, illustrating boundary exchange. In the Arctic Ocean, the model reproduces 230Th measured profiles that the uni-dimensional scavenging model or the scavenging-ventilation model failed to explain. Moreover, if lateral transport is ignored, the 230Th based particle settling speed may by underestimated by a factor 4 at the Arctic Ocean margin. The very low scavenging rate in the open Arctic Ocean combined with the enhanced scavenging at the margin accounts for the lack of high 231Pa/230Th ratio in arctic sediments.

  11. Design study of long-life PWR using thorium cycle

    SciTech Connect

    Subkhi, Moh. Nurul; Su'ud, Zaki; Waris, Abdul

    2012-06-06

    Design study of long-life Pressurized Water Reactor (PWR) using thorium cycle has been performed. Thorium cycle in general has higher conversion ratio in the thermal spectrum domain than uranium cycle. Cell calculation, Burn-up and multigroup diffusion calculation was performed by PIJ-CITATION-SRAC code using libraries based on JENDL 3.2. The neutronic analysis result of infinite cell calculation shows that {sup 231}Pa better than {sup 237}Np as burnable poisons in thorium fuel system. Thorium oxide system with 8%{sup 233}U enrichment and 7.6{approx} 8%{sup 231}Pa is the most suitable fuel for small-long life PWR core because it gives reactivity swing less than 1%{Delta}k/k and longer burn up period (more than 20 year). By using this result, small long-life PWR core can be designed for long time operation with reduced excess reactivity as low as 0.53%{Delta}k/k and reduced power peaking during its operation.

  12. Investigation of heavy-ion fusion with deformed surface diffuseness: Actinide and lanthanide targets

    NASA Astrophysics Data System (ADS)

    Alavi, S. A.; Dehghani, V.

    2017-05-01

    By using a deformed Broglia-Winther nuclear interaction potential in the framework of the WKB method, the near- and above-barrier heavy-ion-fusion cross sections of 16O with some lanthanides and actinides have been calculated. The effect of deformed surface diffuseness on the nuclear interaction potential, the effective interaction potential at distinct angle, barrier position, barrier height, cross section at each angles, and fusion cross sections of 16O+147Sm,150Nd,154Sm , and 166Er and 16O+232Th,238U,237Np , and 248Cm have been studied. The differences between the results obtained by using deformed surface diffuseness and those obtained by using constant surface diffuseness were noticeable. Good agreement between experimental data and theoretical calculation with deformed surface diffuseness were observed for 16O+147Sm,154Sm,166Er,238U,237Np , and 248Cm reactions. It has been observed that deformed surface diffuseness plays a significant role in heavy-ion-fusion studies.

  13. Radionuclide desorption kinetics on synthetic Zn/Ni-labeled montmorillonite nanoparticles

    NASA Astrophysics Data System (ADS)

    Huber, F. M.; Heck, S.; Truche, L.; Bouby, M.; Brendlé, J.; Hoess, P.; Schäfer, T.

    2015-01-01

    Sorption/desorption kinetics for selected radionuclides (99Tc(VII), 232Th(IV), 233U(VI), 237Np(V), 242Pu and 243Am(III)) under Grimsel (Switzerland) ground water conditions (pH 9.7 and ionic strength of ∼1 mM) in the presence of synthetic Zn or Ni containing montmorillonite nanoparticles and granodiorite fracture filling material (FFM) from Grimsel were examined in batch studies. The structurally bound Zn or Ni in the octahedral sheet of the synthetic colloids rendered them suitable as colloid markers. Only a weak interaction of the montmorillonite colloids with the fracture filling material occurs over the experimental duration of 10,000 h (∼13 months). The tri- and tetravalent radionuclides are initially strongly associated with nanoparticles in contrast to 99Tc(VII), 233U(VI) and 237Np(V) which showed no sorption to the montmorillonite colloids. Radionuclide desorption of the nanoparticles followed by sorption to the fracture filling material is observed for 232Th(IV), 242Pu and 243Am(III). Based on the conceptual model that the driving force for the kinetically controlled radionuclide desorption from nanoparticles and subsequent association to the FFM is the excess in surface area offered by the FFM, the observed desorption kinetics are related to the colloid/FFM surface area ratio. The observed decrease in concentration of the redox sensitive elements 99Tc(VII), 233U(VI) and 237Np(V) may be explained by reduction to lower oxidation states in line with Eh-pH conditions prevailing in the experiments and thermodynamic considerations leading to (i) precipitation of a sparingly soluble phase, (ii) sorption to the fracture filling material, (iii) possible formation of eigencolloids and/or (iv) sorption to the montmorillonite colloids. Subsequent to the sorption/desorption kinetics study, an additional experiment was conducted investigating the potential remobilization of radionuclides/colloids attached to the FFM used in the sorption/desorption kinetic

  14. Theoretical studies of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in young lavas produced by mantle melting

    SciTech Connect

    Zou, H.; Zindler, A.

    2000-05-01

    This paper provides ready-to-use equations to describe variations in uranium-series (U-series) disequilibrium as a function of elemental distribution coefficients, melting porosity, melting rate, and melting time. The effects of these melting parameters on U-series disequilibria are quantitatively evaluated in both an absolute and relative sense. The importance of net elemental fractionation and ingrowth of daughter nuclides are also described and compared in terms of their relative contributions to total U-series disequilibrium. In addition, the authors compare the production of U-series disequilibrium during mantle melting to trace element fractionations produced by melting in a similar context. Trace element fractionations depend externally on the degree to which a source is melted, whereas U-series disequilibrium depends upon both the degree and rate of melting. In contrast to previous models, their approach to modeling U-series disequilibrium during dynamic melting collapses simply to a description of trace element behavior during dynamic melting when the appropriate decay terms are omitted. Their formulation shows that extremely small degrees of melting, sometimes called upon to explain observed extents of U-series disequilibrium, are not always required.

  15. U-series disequilibrium of basaltic rocks from Kick'em-Jenny submarine volcano, Lesser Antilles island arc

    NASA Astrophysics Data System (ADS)

    Huang, F.; Lundstrom, C. C.

    2005-12-01

    Kick'em Jenny (KEJ) submarine volcano located 9 km to the north of Grenada in the Lesser Antilles volcanic arc produces lavas ranging in composition from high MgO basalts to moderately evolved andesites. We have determined U-series disequilibria in 12 porphyritic lavas erupted from KEJ volcano by TIMS and MC-ICP-MS methods to constrain the timing and identify the processes creating the magma diversity observed. The SiO2 contents of samples studied here vary from 47 to 55 wt.% SiO2 while REE patterns evolve from slightly LREE enriched, MREE/HREE = 1 patterns to strongly LREE enriched, MREE depleted concave-up patterns. Separate dissolutions of sample KEJ100 indicate an external reproducibility (1s) of 0.7% for (230Th/238U) (n=4), 0.8% for (230Th/232Th) (n=4) and 0.6% for (226Ra/230Th) (n=3), respectively. For all sample, (234U/238U) lies within 0.7% of unity, suggesting that secondary alteration by seawater has not disturbed the U-series data significantly. Sample ages for these submarine erupted samples are unknown, resulting in uncertain values for initial (226Ra/230Th); however, 10 out of 12 of the measured (226Ra/230Th) range between 3.16 and 1.13 and are thus unequivocally young with respect to decay of 230Th and 231Pa since eruption. The U (0.535 - 4.876 ppm) and Th (1.25 - 10.78 ppm) concentrations increase with SiO2 contents. (230Th/232Th) has a restricted range, varying from 0.994 to 1.093 with the exception of one sample. (230Th/238U) ranges from 0.684 to 0.875 while (231Pa/235U) ranges from 1.76 up to 2.84, among the highest 231Pa excess in island arcs yet reported. These data confirm previous observations of the unusual behavior of KEJ lavas relative to global observations in having both large 238U and 231Pa excesses. Combined with (226Ra/230Th), these disequilibria observations require that 238U excesses reflect more than solely fluid addition to the mantle wedge from the subducted oceanic slab.

  16. Large Scale Accelerator Production of 225Ac: Effective Cross sections for 78-192 MeV Protons Incident on 232Th Targets

    DOE PAGES

    Griswold, Justin R; Medvedev, Dmitri G.; Engle, Jonathan W.; ...

    2016-09-28

    Actinium-225 and 213Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of 225Ac. The high energy proton spallation reaction on natural thorium metal target has been utilized to produce millicurie quantities of 225Ac. The results of sixteen irradiation experiments of Th metal at beam energies between 78 and 200 MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridgemore » National Laboratory (ORNL). Excitation functions for actinium and thorium isotopes as well as for some of the fission products are presented. The cross sections for production of 225Ac range from 3.6 to 16.7 mb in the incident proton energy range of 78 to 192 MeV. Based on these data, production of Curie quantities of 225Ac is possible by irradiating a 5.0 g cm-2232Th target for 10 days in either BNL or LANL proton irradiation facilities.« less

  17. Preliminary Results on Direct Observation of True Ternary fission in the reaction {sup 232}Th+d (10 MeV)

    SciTech Connect

    Pyatkov, Yu.; Kamanin, D.; Alexandrov, A.; Alexandrova, I.; Kondratyev, N.; Kuznetsova, E.; Tyukavkin, A.; Zhuchko, V.; Krasznohorkay, A.; Csatlos, M.; Csige, L.; Gulyas, J.; Naqvi, F.; Tornyi, T.

    2010-04-30

    Results of the first direct observation of the true ternary fission of {sup 234}Pa* nucleus are presented. The yield of the effect depending of the experimental geometry is about 10{sup -5}/binary fission. Mass of the lightest fragment in the triplet lies mainly in the range of (20 divide 40) a.m.u. Connection between the effect and known heavy ion or lead radioactivity is discussed.

  18. Comparative study of different analytical methods for the determination of 238U, 234U, 235U, 230Th and 232Th in NORM samples (Southern Catalonia).

    PubMed

    Mola, M; Palomo, M; Peñalver, A; Borrull, F; Aguilar, C

    2013-01-01

    Uranium and thorium isotopes from sludge samples taken from an area of influence of a dicalcium phosphate factory, located close to the Ebro River reservoir in Flix, and from mineral raw materials (coal and phosphate) which were deposited in Tarragona Harbour (Catalonia) have been measured. To do that, several procedures to determine these isotopes have been applied and compared in terms of accuracy, precision and total analysis time. In particular, digestion procedures, such as one based on conventional acidic digestion or another based on the use of microwave digestion, have been tested. Moreover, different radiochemical separation procedures have been applied. In this regard, one method based on liquid-liquid extraction using TBP/Xylene and another based on the use of extraction chromatography using UTEVA resins have been compared. Firstly, the different proposed methods were tested by analyzing a phosphogypsum sediment and a moss-soil sample from two different intercomparison exercises. The microwave digestion - UTEVA method provided the best results (recoveries higher than 82% for uranium and thorium isotopes) and was then applied to the NORM samples. The obtained results showed that the higher uranium and thorium activities values were found in phosphate raw material and in the more superficial samples located in sludge sediments next to the dicalcium phosphate factory. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Total half-lives for selected nuclides

    SciTech Connect

    Holden, N.E.

    1989-01-01

    Measurements of the half-lives of {sup 3}H, {sup 10}Be, {sup 14}C, {sup 26}Al, {sup 40}K, {sup 39}Ar, {sup 53}Mn, {sup 87}Rb, {sup 92}Nb, {sup 129}I, {sup 138}La, {sup 147}Sm, {sup 176}Lu, {sup 174}Hf, {sup 180}Ta, {sup 187}Re, {sup 186}Os, {sup 190}Pt, {sup 204}Pb, {sup 210}Pb, {sup 210}Po, {sup 222}Rn, {sup 224}Th, {sup 226}Ra, {sup 227}Ac, {sup 228}Ra, {sup 228}Th, {sup 230}Th, {sup 232}Th, {sup 231}Pa have been compiled and evaluated. The effect of the {sup 14}C half-life value on carbon dating ages is discussed as well as the stability of {sup 204}Pb. 237 refs., 30 tabs.

  20. The Role of Flux Melting on U-series Systematics of Young Lavas from Costa Rica and Nicaragua

    NASA Astrophysics Data System (ADS)

    Thomas, R. B.; Hirschmann, M. M.; Reagan, M. K.; Cheng, H.; Edwards, R. L.

    2001-12-01

    We have acquired U, Th and Pa isotope data for young lavas that derive from source regions affected by slab fluid addition that ranges in magnitude from minor beneath Costa Rica to substantial beneath Nicaragua. Four of the five Costa Rican samples have (231Pa/235U) and (230Th/238U)>1 five out of six Nicaraguan lavas have (230Th/238U)<1 and (231Pa/235U)>1, but (231Pa/235U) ranges to lower values in Nicaragua. On a (231Pa/235U) vs. (230Th/238U) diagram, the data, though limited in number, seem to define two trends with decreasing (230Th/238U), one with a slope of ~2.5 and the other with a slope of ~0.7. Trace element ratios indicate that the latter were affected more by addition of hemipelagic sediment, suggesting a link between subduction-fluid source and Pa-Th-U systematics. The combined 231Pa-235U and 232Th-238U-230Th data provide constraints on the timing and mechanisms of fluid addition and partial melting beneath the Central American arc. Significant (231Pa/235U) excesses (>1.5) in both Costa Rica and Nicaragua require a melting process that allows for ingrowth, as simple batch or fractional melting cannot explain the excesses at melt fractions large enough to explain trace element abundances and ratios. We propose a flux-ingrowth melting model in which the mantle wedge flows downward with the subducting slab and partially melts as fluid is added to regions with suitably hot temperature. We assume critical melting at low porosity ( ~10-3) and that melt extraction and transport are rapid enough (< 8 kyr) to preserve observed 226Ra excesses. Because solid mantle may traverse the melting region over 105-106 yrs., 231Pa and 230Th ingrow from U retained in the matrix. Magmas are aggregated instantaneously from all parts of the melting regime. This flux-ingrowth model matches a wide range of U-series and trace element data from Costa Rican and Nicaraguan lavas, with required average extents of melting of ~1% and 8-10%, respectively. Integration of melts from regions

  1. Scavenging of Thorium and Protactinium by Particles from the East Pacific Rise Hydrothermal Plume

    NASA Astrophysics Data System (ADS)

    Anderson, R. F.; Fleisher, M. Q.; Pavia, F. J.; Vivancos, S. M.; Lu, Y.; Cheng, H.; Edwards, R. L.

    2014-12-01

    Concentrations of dissolved 230Th, 231Pa and 232Th measured along the US GEOTRACES Eastern Pacific Zonal Transect between Peru and Tahiti illustrate the enhanced scavenging of trace elements by particles derived from the hydrothermal plume that spreads westward from the East Pacific Rise (EPR). Concentrations of dissolved 230Th and 231Pa increase linearly with depth in the upper 2 km of the water column, consistent with their removal by reversible scavenging. The intensity of scavenging by plume particles is quantified by comparing the predicted (extrapolated) concentration of dissolved 230Th at the core depth of the plume (30 to 35 fg/kg) with measured concentrations. Within the core of the plume, measured concentrations of dissolved 230Th are 8 fg/kg at a distance of approx. 1200 km to the west of the EPR, and 12 fg/kg at a distance approx 2500 km to the west of the ridge, much less than the predicted value. Particles derived from the EPR plume potentially impact the scavenging and removal of many trace elements from the deep ocean over a broad area of the eastern tropical South Pacific.

  2. Development and comparison of five site-specific biosphere models for safety assessment of radioactive waste disposal.

    PubMed

    Pröhl, G; Olyslaegers, G; Kanyar, B; Pinedo, P; Bergström, U; Mobbs, S; Eged, K; Katona, T; Simón, I; Hallberg, U B; Chen, Q; Kowe, R; Zeevaert, T

    2005-12-01

    This paper describes the development and application of site-specific biosphere models that might be used for assessment of potential exposures in the framework of performance assessment studies of nuclear waste disposals. Model development follows the Reference Biosphere Methodology that has been set up in the framework of the BIOMASS study. In this paper, the application is to real sites at five European locations for which environmental and agricultural conditions have been described and characterised. For each of the sites a biosphere model has been developed specifically assuming a release of radionuclides to waters that are used by humans, for example as drinking water for humans and cattle and as irrigation water. Among the ingestion pathways, the intakes of drinking water, cereals, leafy vegetables, potatoes, milk, beef and freshwater fish are included in all models. Annual individual doses were calculated, and uncertainties in the results were estimated by means of stochastic calculations. To enable a comparison, all results were normalised to an activity concentration in groundwater of 1 Bq m(-3) for each of the radionuclides considered ((36)Cl, (79)Se, (99)Tc, (129)I, (135)Cs, (226)Ra, (231)Pa, (230)Th, (237)Np, (239)Pu, and (238)U), i.e. those that are usually most relevant in performance assessment studies of nuclear waste disposals. Although the results do not give answers in absolute terms on potential future exposures, they indicate the spectrum of exposures that might occur in different environments and specify the interaction of environmental conditions, human habits and potential exposure.

  3. A comparative radiological assessment of five European biosphere systems in the context of potential contamination of well water from the hypothetical disposal of radioactive waste.

    PubMed

    Olyslaegers, G; Zeevaert, T; Pinedo, P; Simon, I; Pröhl, G; Kowe, R; Chen, Q; Mobbs, S; Bergström, U; Hallberg, B; Katona, T; Eged, K; Kanyar, B

    2005-12-01

    In the framework of the BioMoSA project for the development of biosphere assessment models for radioactive waste disposal the Reference Biosphere Methodology developed in the IAEA programme BIOMASS was applied to five locations, situated in different European countries. Specific biosphere models were applied to assess the hypothetical contamination of a range of agricultural and environmental pathways and the dose to individuals, following contamination of well water. The results of these site-specific models developed by the different BioMoSA partners, and the individual normalised dose to the exposure groups were compared against each other. Ingestion of drinking water, fruit and vegetables were found to be among the most important pathways for almost all radionuclides. Stochastic calculations revealed that consumption habits, transfer factors, irrigation rates and distribution coefficients (Kd(s)) were the most important parameters that influence the end results. Variations in the confidence intervals were found to be higher for sorbing elements (e.g. (36)Cl, (237)Np, (99)Tc, (238)U, (129)I) than for mobile elements (e.g. (226)Ra, (79)Se, (135)Cs, (231)Pa, (239)Pu). The influence of daughter products, for which the distribution into the biosphere was calculated individually, was also shown to be important. This paper gives a brief overview of the deterministic and stochastic modelling results and the parameter sensitivity. A screening methodology was introduced to identify the most important pathways, simplify a generic biosphere tool and refine the existing models.

  4. Study of calculated and measured time dependent delayed neutron yields. [TX, for calculating delayed neutron yields; MATINV, for matrix inversion; in FORTRAN for LSI-II minicomputer

    SciTech Connect

    Waldo, R.W.

    1980-05-01

    Time-dependent delayed neutron emission is of interest in reactor design, reactor dynamics, and nuclear physics studies. The delayed neutrons from neutron-induced fission of /sup 232/U, /sup 237/Np, /sup 238/Pu, /sup 241/Am, /sup 242m/Am, /sup 245/Cm, and /sup 249/Cf were studied for the first time. The delayed neutron emission from /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu, /sup 241/Pu, and /sup 242/Pu were measured as well. The data were used to develop an empirical expression for the total delayed neutron yield. The expression gives accurate results for a large variety of nuclides from /sup 232/Th to /sup 252/Cf. The data measuring the decay of delayed neutrons with time were used to derive another empirical expression predicting the delayed neutron emission with time. It was found that nuclides with similar mass-to-charge ratios have similar decay patterns. Thus the relative decay pattern of one nuclide can be established by any measured nuclide with a similar mass-to-charge ratio. A simple fission product yield model was developed and applied to delayed neutron precursors. It accurately predicts observed yield and decay characteristics. In conclusion, it is possible to not only estimate the total delayed neutron yield for a given nuclide but the time-dependent nature of the delayed neutrons as well. Reactors utilizing recycled fuel or burning actinides are likely to have inventories of fissioning nuclides that have not been studied until now. The delayed neutrons from these nuclides can now be incorporated so that their influence on the stability and control of reactors can be delineated. 8 figures, 39 tables.

  5. Review and Assessment of Neutron Cross Section and Nubar Covariances for Advanced Reactor Systems

    SciTech Connect

    Maslov,V.M.; Oblozinsky, P.; Herman, M.

    2008-12-01

    In January 2007, the National Nuclear Data Center (NNDC) produced a set of preliminary neutron covariance data for the international project 'Nuclear Data Needs for Advanced Reactor Systems'. The project was sponsored by the OECD Nuclear Energy Agency (NEA), Paris, under the Subgroup 26 of the International Working Party on Evaluation Cooperation (WPEC). These preliminary covariances are described in two recent BNL reports. The NNDC used a simplified version of the method developed by BNL and LANL that combines the recent Atlas of Neutron Resonances, the nuclear reaction model code EMPIRE and the Bayesian code KALMAN with the experimental data used as guidance. There are numerous issues involved in these estimates of covariances and it was decided to perform an independent review and assessment of these results so that better covariances can be produced for the revised version in future. Reviewed and assessed are uncertainties for fission, capture, elastic scattering, inelastic scattering and (n,2n) cross sections as well as prompt nubars for 15 minor actinides ({sup 233,234,236}U, {sup 237}Np, {sup 238,240,241,242}Pu, {sup 241,242m,243}Am and {sup 242,243,244,245}Cm) and 4 major actinides ({sup 232}Th, {sup 235,238}U and {sup 239}Pu). We examined available evaluations, performed comparison with experimental data, taken into account uncertainties in model parameterization and made use state-of-the-art nuclear reaction theory to produce the uncertainty assessment.

  6. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    NASA Astrophysics Data System (ADS)

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Davila, Jesus; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio

    2015-07-01

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e'n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides 232Th, 238U and 237Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  7. Shielding experiments for optimization of shield materials in fast reactor using SSNTDs

    NASA Astrophysics Data System (ADS)

    Kolekar, R. V.; Kumar, R.; Sharma, D. N.

    2013-06-01

    Neutron transport through single shield materials for fast reactor was experimentally studied using solid state nuclear track detectors (SSNTDs) and activation techniques. The single shield materials studied were stainless steel (SS-316), sodium and borated graphite. Neptunium and thorium foil in contact with Lexan track detectors were used to study neutron attenuation in the intermediate neutron energy region. Further, activation detectors using indium foil were also used to study the attenuation in the similar neutron energy region. It is shown in the present paper that SSNTDs can be used as a complimentary to activation detectors used to study deep penetration shielding experiments, where measurements were carried out to study neutron attenuation of the order of 10-4. The fission reaction rates of 237Np having effective threshold energy of 0.6 MeV and 232Th having threshold energy of 1.4 MeV were studied by counting the neutron induced fission track density on Lexan polycarbonate. The reaction rate from 115In(n,n')In115m foils having effective threshold energy of 1.3 MeV was studied by activation techniques.

  8. Prompt and Delayed Inelastic Scattering Reactions from Fission Neutron PGAA - First Results of FaNGaS

    SciTech Connect

    Rossbach, M.; Randriamalala, T.; Revay, Zs.; Kudejova, P.; Soelradel, S.; Wagner, F.

    2015-07-01

    The new instrument Fast Neutron Gamma Spectroscopy (FaNGaS) has been installed at the SR10 beam line of the FRM II Research Reactor in Garching and tested successfully. Complimentary to cold neutron PGAA, with FaNGaS inelastic scattering reactions induced by fission neutrons can be studied. Gamma lines from (n,n'γ) reactions up to now have been rarely studied and no adequate compilation of the emitted gamma energies exist. In developing nondestructive analytical techniques using neutron generator based PGAA such data are badly needed for quantification of heavy metals and actinides in e.g. nuclear waste or safeguards samples. A number of elements and relevant actinides have been irradiated in the fast neutron beam SR10 at the FRM II reactor in Garching, Germany. A heavily shielded 50% eff. HPGe detector perpendicular to the beam is looking at the samples exposed to 2.3 E8 cm{sup -2}s{sup -1} fission neutrons. Prompt gamma spectra have been taken and evaluated using the available data in scattered sources. Additional gamma lines have been detected and are being compiled to create a data base for (n,n') reactions. Particular emphasis is given on actinides including {sup 238}U, {sup 232}Th, {sup 237}Np, {sup 242}Pu and {sup 241}Am. Some examples will be given and first results will be discussed in this contribution. (authors)

  9. Reanalysis of the gas-cooled fast reactor experiments at the zero power facility proteus - Spectral indices

    SciTech Connect

    Perret, G.; Pattupara, R. M.; Girardin, G.; Chawla, R.

    2012-07-01

    The gas-cooled fast reactor (GCFR) concept was investigated experimentally in the PROTEUS zero power facility at the Paul Scherrer Inst. during the 1970's. The experimental program was aimed at neutronics studies specific to the GCFR and at the validation of nuclear data in fast spectra. A significant part of the program used thorium oxide and thorium metal fuel either distributed quasi-homogeneously in the reference PuO{sub 2}/UO{sub 2} lattice or introduced in the form of radial and axial blanket zones. Experimental results obtained at the time are still of high relevance in view of the current consideration of the Gas-cooled Fast Reactor (GFR) as a Generation-IV nuclear system, as also of the renewed interest in the thorium cycle. In this context, some of the experiments have been modeled with modern Monte Carlo codes to better account for the complex PROTEUS whole-reactor geometry and to allow validating recent continuous neutron cross-section libraries. As a first step, the MCNPX model was used to test the JEFF-3.1, JEFF-3.1.1, ENDF/B-VII.0 and JENDL-3.3 libraries against spectral indices, notably involving fission and capture of {sup 232}Th and {sup 237}Np, measured in GFR-like lattices. (authors)

  10. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    SciTech Connect

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio; Davila, Jesus

    2015-07-23

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  11. Dose coefficients and derived guidance and clinical decision levels for contaminated wounds

    SciTech Connect

    Bertelli, Luiz; Toohey, Richard E

    2009-01-01

    The NCRP Wound Model describing the retention of selected radionuclides at the site of a contaminated wound and their uptake into the transfer compartment has been combined with the ICRP element-specific systemic models for those radionuclides to derive dose coefficients for intakes via contaminated wounds. Those coefficients have been used to generate derived guidance levels (i.e., the activity in a wound that would result in an effective dose of 20 or 50 mSv, or in some cases, a committed organ equivalent dose of 500 mSv), and clinical decision levels (i.e., activity levels that would indicate the need for consideration of medical intervention to remove activity from the wound site or administration of decorporation therapy or both), typically set at 5 times the derived guidance levels. Data are provided for the radionuclides commonly encountered at nuclear power plants and nuclear weapons, fuel fabrication or recycling, waste disposal, medical and research facilities. These include: {sup 60}Co, {sup 90}Sr, {sup 99m}Tc, {sup 131}I, {sup 137}Cs, {sup 192}Ir, {sup 210}Po, {sup 226,228}Ra, {sup 228,232}Th, {sup 235,238}U, {sup 237}Np, {sup 238,239}Pu, {sup 241}Am, {sup 242,244}Cm, and {sup 252}Cf.

  12. Update of the α - n Yields for Reactor Fuel Materials for the Interest of Nuclear Safeguards

    NASA Astrophysics Data System (ADS)

    Simakov, S. P.; van den Berg, Q. Y.

    2017-01-01

    The neutron yields caused by spontaneous α-decay of actinides and subsequent (α,xn) reactions were re-evaluated for the reactor fuel materials UO2, UF6, PuO2 and PuF4. For this purpose, the most recent reference data for decay parameters, α-particle stopping powers and (α,xn) cross sections were collected, analysed and used in calculations. The input data and elaborated code were validated against available thick target neutron yields in pure and compound materials measured at accelerators or with radioactive sources. This paper provides the specific neutron yields and their uncertainties resultant from α-decay of actinides 241Am, 249Bk, 252Cf, 242,244Cm, 237Np, 238-242Pu, 232Th and 232-236,238U in oxide and fluoride compounds. The obtained results are an update of previous reference tables issued by the Los Alamos National Laboratory in 1991 which were used for the safeguarding of radioactive materials by passive non-destructive techniques. The comparison of the updated values with previous ones shows an agreement within one estimated uncertainty (≈ 10%) for oxides, and deviations of up to 50% for fluorides.

  13. Rapid determination of actinides and (90)Sr in river water.

    PubMed

    Habibi, A; Boulet, B; Gleizes, M; Larivière, D; Cote, G

    2015-07-09

    Nuclear accidents occurred in latest years highlighted the difficulty to achieve, in a short time, the quantification of alpha and beta emitters. Indeed, most of the existing methods, though displaying excellent performances, can be very long, taking up to several weeks for some radioisotopes, such as (90)Sr. This study focuses on alpha and beta radioisotopes which could be accidentally released from nuclear installations and which could be measured by inductively coupled plasma mass spectrometer (ICP-MS). Indeed, a new and rapid separation method was developed for (234,235,236,238)U, (230,232)Th, (239,240)Pu, (237)Np, (241)Am and (90)Sr. The main objective was to minimize the duration of the separation protocol by the development of a unique radiochemical procedure with elution media compatible with ICP-MS measurements. Excellent performances were obtained with spiked river water samples. These performances are characterized by total yields exceeding 80% for all monitored radionuclides, as well as good reproducibility (RSD≤10%, n=12). The proposed radiochemical separation (including counting time) required less than 7h for a batch of 8 samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Accumulation rates of Th-230, Pa-231, and some transition metals on the Bermuda Rise

    USGS Publications Warehouse

    Bacon, M.P.; Rosholt, J.N.

    1982-01-01

    Measurements of 238U, 234U, 230Th, 232Th, 231Pa, Mn, Fe, Co, Ni, Cu, and Zn were made on 23 samples from core GPC-5, a 29-m giant piston core from a water depth of 4583 m on the northeastern Bermuda Rise (33??41.2???N, 57??36.9???W). This area is characterized by rapid deposition of sediment transported by abyssal currents. Unsupported 230Th and 231Pa are present throughout the core but, because of large variations in the sedimentation rate, show marked departures from exponential decay with depth. The trend with depth of the 231Paex 230Thex ratio is consistent with the average accumulation rate of 36 cm/1000 y reported earlier on the basis of radiocarbon dating and CaCO3 stratigraphy. When expressed on a carbonate-free basis, concentrations of Mn, Co, Ni, Cu, Zn, 230Thex, and 231Paex all show cyclic variations positively correlated with those of CaCO3. The correlations can be explained by a model in which all of these constituents, including CaCO3, are supplied to the sediments from the water column at a constant rate. Concentration variations are controlled mainly by varying inputs of terrigenous detritus, with low inputs occurring during interglacials and high inputs during glacials. Relationships between the metal and 230Thex concentrations permit estimates of the rates at which the metals are removed to the sediment by scavenging from the water column. The results, in ??g/cm2-1000 y, are: 4300 ?? 1100 for Mn, 46 ?? 16 for Ni and 76 ?? 26 for Cu. These rates are somewhat larger than ocean-wide averages estimated by other methods, and the absolute rate of 230Th accumulation in GPC-5 averages about nine times higher than production in the overlying water column. This part of the Bermuda Rise and similar bottom-current deposits may act as important accumulators of elements scavenged from seawater. ?? 1982.

  15. U-Th-Ra-Pa Disequilibria in the Kasuga Seamounts: recent "sediment" flux melting in the Mariana rear arc

    NASA Astrophysics Data System (ADS)

    Gill, J.; Holden, P.

    2002-12-01

    Mariana volcanic front lavas define a U-Th isotope mixing line with an apparent age of 30 Ka between U-enriched "basalt fluid"-dominated Guguan and "sediment melt"-dominated Uracas in 238U-230Th equilibrium (Elliott et al., 1997). However, new results for basalts collected by dredging and diving on the shoshonitic Kasuga Seamounts, 10-20 km behind the VF, require re-interpretation of both Mariana components. Kasuga basalts are the local "sediment" extreme, reaching La/Sm = 5, Th/Nb=0.75, and eNd=3 in the most K-rich samples. Despite this extremity, their U-Th disequilibria lie along the same mixing line as for the VF, but extend to 20 percent 230Th-enrichment and (230Th)/(232Th) lower than at the intersection with the equiline. This indicates deeper melting than at the VF, and that the source's Th/U ratio was higher than the intersection. (226Ra)/(230Th) ratios extend to 3.5 even though samples have unknown eruption ages and Ba/Th is only 100, much lower than at the VF. (231Pa)/(235U) is mostly 1.7, higher than at the VF. (231Pa)/(230Th) correlates positively with excess U, consistent with recent flux melting. However, the mantle being melted is more fertile than at the VF, and the flux is more "sedimentary" apart from its disequilibria. Disequilibria in the highest-K Kasuga are most like Kick-em-Jenny, the most sediment-rich part of the Antilles.

  16. 238U, 232Th, 222Rn, AND 220Rn concentrations measured in various bottled mineral waters and resulting radiation doses to the members of the European population living in the city of Marrakech (Morocco).

    PubMed

    Misdaq, M A; Chaouqi, A

    2008-03-01

    U, Th, Rn, and Rn concentrations were measured in thirteen bottled mineral water samples from Morocco, France, and Italy widely consumed by the European population living in the city of Marrakech (Morocco) by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). K contents were also evaluated in the same mineral water samples. The measured concentrations of U, Th, Rn, Rn, and K ranged from (4.2 +/- 0.2) mBq L to (8.6 +/- 0.6) mBq L, (0.90 +/- 0.05) mBq L to (3.4 +/- 0.3) mBq L, (4.2 +/- 0.2) Bq L to (8.6 +/- 0.6) Bq L, (0.91 +/- 0.06) Bq L to (3.4 +/- 0.2) Bq L and 15 mBq L to 1,082 mBq L, respectively. Alpha activities due to the annual intakes of U, Th, and Rn were assessed in the tissues and organs of the human body of the considered consumers. Committed equivalent doses due to annual intakes of U, Th, and Rn were evaluated in the human body compartments of adult members of the European population living in Marrakech. The influence of the target tissue mass and activities due to U, Th, and Rn on the annual committed equivalent doses in the compartments of the human body was investigated.

  17. Preliminary results of calculations for heavy-water nuclear-power-plant reactors employing {sup 235}U, {sup 233}U, and {sup 232}Th as a fuel and meeting requirements of a nonproliferation of nuclear weapons

    SciTech Connect

    Ioffe, B. L.; Kochurov, B. P.

    2012-02-15

    A physical design is developed for a gas-cooled heavy-water nuclear reactor intended for a project of a nuclear power plant. As a fuel, the reactor would employ thorium with a small admixture of enriched uranium that contains not more than 20% of {sup 235}U. It operates in the open-cycle mode involving {sup 233}U production from thorium and its subsequent burnup. The reactor meets the conditions of a nonproliferation of nuclear weapons: the content of fissionable isotopes in uranium at all stages of the process, including the final one, is below the threshold for constructing an atomic bomb, the amount of product plutonium being extremely small.

  18. Preliminary results of calculations for heavy-water nuclear-power-plant reactors employing 235U, 233U, and 232Th as a fuel and meeting requirements of a nonproliferation of nuclear weapons

    NASA Astrophysics Data System (ADS)

    Ioffe, B. L.; Kochurov, B. P.

    2012-02-01

    A physical design is developed for a gas-cooled heavy-water nuclear reactor intended for a project of a nuclear power plant. As a fuel, the reactor would employ thorium with a small admixture of enriched uranium that contains not more than 20% of 235U. It operates in the open-cycle mode involving 233U production from thorium and its subsequent burnup. The reactor meets the conditions of a nonproliferation of nuclear weapons: the content of fissionable isotopes in uranium at all stages of the process, including the final one, is below the threshold for constructing an atomic bomb, the amount of product plutonium being extremely small.

  19. Computational simulation of (nat)UO2, (232)ThO2 and U3O8-Al pills to estimate (p,fission) (99)Mo yield in the modeled targets irradiated by CYCLONE30 accelerator.

    PubMed

    Jozvaziri, Atieh; Gholamzadeh, Zohreh; Yousefi, Kamran; Mirvakili, Seyed Mohammad; Alizadeh, Masoomeh; Aboudzadeh, Mohammadreza

    2017-03-01

    (99)Mo is important for both therapy and imaging purposes. Accelerator and reactor-based procedures are applied to produce it. Newly proton-fission method has been taken in attention by some research centers. In the present work, computationally investigation of the (99)Mo yield in different fissionable targets irradiated by proton was aimed. The results showed UO2 pill target could be efficiently used to produce 11.12Ci/g-U saturation yield of (99)Mo using 25MeV proton irradiation of the optimized-dimension target with 70µA current. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Fluxes of metals to a manganese nodule: Radiochemical, chemical, structural, and mineralogical studies

    USGS Publications Warehouse

    Moore, W.S.; Ku, T.-L.; Macdougall, J.D.; Burns, V.M.; Burns, R.; Dymond, J.; Lyle, M.W.; Piper, D.Z.

    1981-01-01

    Fluxes of metals to the top and bottom surfaces of a manganese nodule were determined by combining radiochemical (230Th, 231Pa, 232Th, 238U, 234U) and detailed chemical data. The top of the nodule had been growing in its collected orientation at 4.7 mm Myr-1 for at least 0.5 Myr and accreting Mn at 200 ??g cm-2 kyr-1. The bottom of the nodule had been growing in its collected orientation at about 12 mm Myr-1 for at least 0.3 Myr and accreting Mn at about 700 ??g cm-2 yr-1. Although the top of the nodule was enriched in iron relative to the bottom, the nodule had been accreting Fe 50% faster on the bottom. 232Th was also accumulating more rapidly in the bottom despite a 20-fold enrichment of 230Th on the top. The distribution of alpha-emitting nuclides calculated from detailed radiochemical measurements matched closely the pattern revealed by 109-day exposures of alpha-sensitive film to the nodule. However, the shape and slope of the total alpha profile with depth into the nodule was affected strongly by 226Ra and 222Rn migrations making the alpha-track technique alone an inadequate method of measuring nodule growth rates. Diffusion of radium in the nodule may have been affected by diagenetic reactions which produce barite, phillipsite and todorokite within 1 mm of the nodule surface; however, our sampling interval was too broad to document the effect. We have not been able to resolve the importance of nodule diagenesis on the gross chemistry of the nodule. ?? 1981.

  1. Application of the Spanish methodological approach for biosphere assessment to a generic high-level waste disposal site.

    PubMed

    Agüero, A; Pinedo, P; Simón, I; Cancio, D; Moraleda, M; Trueba, C; Pérez-Sánchez, D

    2008-09-15

    A methodological approach which includes conceptual developments, methodological aspects and software tools have been developed in the Spanish context, based on the BIOMASS "Reference Biospheres Methodology". The biosphere assessments have to be undertaken with the aim of demonstrating compliance with principles and regulations established to limit the possible radiological impact of radioactive waste disposals on human health and on the environment, and to ensure that future generations will not be exposed to higher radiation levels than those that would be acceptable today. The biosphere in the context of high-level waste disposal is defined as the collection of various radionuclide transfer pathways that may result in releases into the surface environment, transport within and between the biosphere receptors, exposure of humans and biota, and the doses/risks associated with such exposures. The assessments need to take into account the complexity of the biosphere, the nature of the radionuclides released and the long timescales considered. It is also necessary to make assumptions related to the habits and lifestyle of the exposed population, human activities in the long term and possible modifications of the biosphere. A summary on the Spanish methodological approach for biosphere assessment are presented here as well as its application in a Spanish generic case study. A reference scenario has been developed based on current conditions at a site located in Central-West Spain, to indicate the potential impact to the actual population. In addition, environmental change has been considered qualitatively through the use of interaction matrices and transition diagrams. Unit source terms of (36)Cl, (79)Se, (99)Tc, (129)I, (135)Cs, (226)Ra, (231)Pa, (238)U, (237)Np and (239)Pu have been taken. Two exposure groups of infants and adults have been chosen for dose calculations. Results are presented and their robustness is evaluated through the use of uncertainty and

  2. Forecast of Standard Atomic Weights for the Mononuclidic Elements – 2011

    SciTech Connect

    Holden, N.E.; Holden, N.; Holden,N.E.

    2011-07-27

    In this short report, I will provide an early warning about potential changes to the standard atomic weight values for the twenty mononuclidic and the so-called pseudo-mononuclidic ({sup 232}Th and {sup 231}Pa) chemical elements due to the estimated changes in the mass values to be published in the next Atomic Mass Tables within the next two years. There have been many new measurements of atomic masses, since the last published Atomic Mass Table. The Atomic Mass Data Center has released an unpublished version of the present status of the atomic mass values as a private communication. We can not update the Standard Atomic Weight Table at this time based on these unpublished values but we can anticipate how many changes are probably going to be expected in the next few years on the basis of the forthcoming publication of the Atomic Mass Table. I will briefly discuss the procedures that the Atomic Weights Commission used in deriving the recommended Standard Atomic Weight values and their uncertainties from the atomic mass values. I will also discuss some concern raised about a proposed change in the definition of the mole. The definition of the mole is now connected directly to the mass of a {sup 12}C isotope (which is defined as 12 exactly) and to the kilogram. A change in the definition of the mole will probably impact the mass of {sup 12}C.

  3. Coupling of Uranium and Thorium Series Isotope Systematics for Age Determination of Late Pleistocene Zircons using LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Sakata, S.; Hirakawa, S.; Iwano, H.; Danhara, T.; Hirata, T.

    2014-12-01

    Zircon U-Th-Pb dating method is one of the most important tools for estimating the duration of magmatism by means of coupling of uranium, actinium and thorium decay series. Using U-Pb dating method, its reliability is principally guaranteed by the concordance between 238U-206Pb and 235U-207Pb ages. In case of dating Quaternary zircons, however, the initial disequilibrium effect on 230Th and 231Pa should be considered. On the other hands, 232Th-208Pb dating method can be a simple but powerful approach for investigating the age of crystallization because of negligible influence from initial disequilibrium effect. We have developed a new correction model for accurate U-Pb dating of the young zircon samples by taking into consideration of initial disequilibrium and a U-Pb vs Th-Pb concordia diagram for reliable age calibration was successfully established. Hence, the U-Th-Pb dating method can be applied to various zircons ranging from Hadean (4,600 Ma) to Quaternary (~50 ka) ages, and this suggests that further detailed information concerning the thermal history of the geological sequences can be made by the coupling of U-Th-Pb, fission track and Ar-Ar ages. In this presentation, we will show an example of U-Th-Pb dating for zircon samples from Sambe Volcano (3 to 100 ka), southwest Japan and the present dating technique using LA-ICP-MS.

  4. OSMOSE program : statistical review of oscillation measurements in the MINERVE reactor R1-UO2 configuration.

    SciTech Connect

    Stoven, G.; Klann, R.; Zhong, Z.; Nuclear Engineering Division

    2007-08-28

    The OSMOSE program is a collaboration on reactor physics experiments between the United States Department of Energy and the France Commissariat Energie Atomique. At the working level, it is a collaborative effort between the Argonne National Laboratory and the CEA Cadarache Research Center. The objective of this program is to measure very accurate integral reaction rates in representative spectra for the actinides important to future nuclear system designs, and to provide the experimental data for improving the basic nuclear data files. The main outcome of the OSMOSE measurement program will be an experimental database of reactivity-worth measurements in different neutron spectra for the heavy nuclides. This database can then be used as a benchmark to verify and validate reactor analysis codes. The OSMOSE program (Oscillation in Minerve of isotopes in Eupraxic Spectra) aims at improving neutronic predictions of advanced nuclear fuels through oscillation measurements in the MINERVE facility on samples containing the following separated actinides: {sup 232}Th, {sup 233}U, {sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U, {sup 237}Np, {sup 238}Pu, {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, {sup 242}Pu, {sup 241}Am, {sup 243}Am, {sup 244}Cm, and {sup 245}Cm. The first part of this report provides an overview of the experimental protocol and the typical processing of a series of experimental results which is currently performed at CEA-Cadarache. In the second part of the report, improvements to this technique are presented, as well as the program that was created to process oscillation measurement results from the MINERVE facility in the future.

  5. Solar r-process-constrained actinide production in neutrino-driven winds of supernovae

    NASA Astrophysics Data System (ADS)

    Goriely, S.; Janka, H.-Th.

    2016-07-01

    Long-lived radioactive nuclei play an important role as nucleo-cosmochronometers and as cosmic tracers of nucleosynthetic source activity. In particular, nuclei in the actinide region like thorium, uranium, and plutonium can testify to the enrichment of an environment by the still enigmatic astrophysical sources that are responsible for the production of neutron-rich nuclei by the rapid neutron-capture process (r-process). Supernovae and merging neutron-star (NS) or NS-black hole binaries are considered as most likely sources of the r-nuclei. But arguments in favour of one or the other or both are indirect and make use of assumptions; they are based on theoretical models with remaining simplifications and shortcomings. An unambiguous observational determination of a production event is still missing. In order to facilitate searches in this direction, e.g. by looking for radioactive tracers in stellar envelopes, the interstellar medium or terrestrial reservoirs, we provide improved theoretical estimates and corresponding uncertainty ranges for the actinide production (232Th, 235, 236, 238U, 237Np, 244Pu, and 247Cm) in neutrino-driven winds of core-collapse supernovae. Since state-of-the-art supernova models do not yield r-process viable conditions - but still lack, for example, the effects of strong magnetic fields - we base our investigation on a simple analytical, Newtonian, adiabatic and steady-state wind model and consider the superposition of a large number of contributing components, whose nucleosynthesis-relevant parameters (mass weight, entropy, expansion time-scale, and neutron excess) are constrained by the assumption that the integrated wind nucleosynthesis closely reproduces the Solar system distribution of r-process elements. We also test the influence of uncertain nuclear physics.

  6. PRELIMINARY CROSS SECTION AND NU-BAR COVARIANCES FOR WPEC SUBGROUP 26

    SciTech Connect

    ROCHMAN,D.

    2007-01-31

    We report preliminary cross section covariances developed for the WPEC Subgroup 26 for 45 out of 52 requested materials. The covariances were produced in 15- and 187-group representations as follows: (1) 36 isotopes ({sup 16}O, {sup 19}F, {sup 23}Na, {sup 27}Al, {sup 28}Si, {sup 52}Cr, {sup 56,56}Fe, {sup 58}Ni, {sup 90,91,92,94}Zr, {sup 166,167,168,170}Er, {sup 206,207,208}Pb, {sup 209}Bi, {sup 233,234,236}U, {sup 237}Np, {sup 238,240,241,242}Pu, {sup 241,242m,243}Am, {sup 242,243,244,245}Cm) were evaluated using the BNL-LANL methodology. For the thermal region and the resolved and unresolved resonance regions, the methodology has been based on the Atlas-Kalman approach, in the fast neutron region the Empire-Kalman method has been used; (2) 6 isotopes ({sup 155,156,157,158,160}Gd and {sup 232}Th) were taken from ENDF/B-VII.0; and (3) 3 isotopes ({sup 1}H, {sup 238}U and {sup 239}Pu) were taken from JENDL-3.3. For 6 light nuclei ({sup 4}He, {sup 6,7}Li, {sup 9}Be, {sup 10}B, {sup 12}C), only partial cross section covariance results were obtained, additional work is needed and they do not report the results here. Likewise, the cross section covariances for {sup 235}U, which they recommend to take from JENDL-3.3, will be included once the multigroup processing is successfully completed. Covariances for the average number of neutrons per fission, total {nu}-bar, are provided for 10 actinides identified as priority by SG26. Further work is needed to resolve some of the issues and to produce covariances for the full set of 52 materials.

  7. Enumeration of Microbial Populations in Radioactive Environments by Epifluorescence Microscopy

    SciTech Connect

    Pansoy-Hjelvik, M.E.A.; Strietelmeierr, B.A.; Paffett, M.T.; Kitten, S.M.; Leonard, P.A.; Dunn, M.; Gillow, J.B.; Dodge, C.J.; Villarreal, R.; Triay, I.; Francis, A.J.

    1996-12-02

    Epifluorescence microscopy was utilized to enumerate halophilic bacterial populations in two studies involving inoculated, actual radioactive waste/brine mixtures and pure brine solutions. The studies include an initial set of experiments designed to elucidate potential transformations of actinide-containing wastes under salt-repository conditions, including microbially mediated changes. The first study included periodic enumeration of bacterial populations of a mixed inoculum initially added to a collection of test containers. The contents of the test containers are the different types of actual radioactive waste that could potentially be stored in nuclear waste repositories in a salt environment. The transuranic waste was generated from materials used in actinide laboratory research. The results show that cell numbers decreased with time. Sorption of the bacteria to solid surfaces in the test system is discussed as a possible mechanism for the decrease in cell numbers. The second study was designed to determine radiological and/or chemical effects of {sup 239}Pu, {sup 243}Am, {sup 237}Np, {sup 232}Th and {sup 238}U on the growth of pure and mixed anaerobic, denitrifying bacterial cultures in brine media. Pu, Am, and Np isotopes at concentrations of <=1 x 10{sup {minus}5}M, <=5 x 10{sup {minus}6}M and <=5 x 10{sup {minus}4}M respectively, and Th and U isotopes <=4 x 10{sup {minus}3}M were tested in these media. The results indicate that high actinide concentration affected both the bacterial growth rate and morphology. However, relatively minor effects from Am were observed at all tested concentrations with the pure culture.

  8. Enumeration of microbial populations in radioactive environments by epifluorescence microscopy

    SciTech Connect

    Pansoy-Hjelvik, M.E.; Strietelmeier, B.A.; Paffett, M.T.

    1997-01-01

    Epifluorescence microscopy was utilized to enumerate halophilic bacterial populations in two studies involving inoculated, actual waste/brine mixtures and pure brine solutions. The studies include an initial set of experiments designed to elucidate potential transformations of actinide-containing wastes under salt-repository conditions, including microbially mediated changes. The first study included periodic enumeration of bacterial populations of a mixed inoculum initially added to a collection of test containers. The contents of the test containers are the different types of actual radioactive waste that could potentially be stored in nuclear waste repositories in a salt environment. The transuranic waste was generated from materials used in actinide laboratory research. The results show that cell numbers decreased with time. Sorption of the bacteria to solid surfaces in the test system is discussed as a possible mechanism for the decrease in cell numbers. The second study was designed to determine radiological and/or chemical effects of {sup 239}Pu, {sup 243}Am, {sup 237}Np, {sup 232}Th and {sup 238}U on the growth of pure and mixed anaerobic, denitrifying bacterial cultures in brine media. Pu, Am, and Np isotopes at concentrations of {le}1x10{sup -6} M , {le}5x10{sup -6} M and {le}5x10{sup -4}M respectively, and Th and U isotopes {le}4x10{sup -3}M were tested in these media. The results indicate that high concentrations of certain actinides affected both the bacterial growth rate and morphology. However, relatively minor effects from Am were observed at all tested concentrations with the pure culture.

  9. Analysis of trace neptunium in the vicinity of underground nuclear tests at the Nevada National Security Site

    DOE PAGES

    Zhao, P.; Tinnacher, R. M.; Zavarin, M.; ...

    2014-11-01

    A high sensitivity analytical method for 237Np analysis was developed and applied to groundwater samples from the Nevada National Security Site (NNSS) using short-lived 239Np as a yield tracer and HR magnetic sector ICP-MS. The 237Np concentrations in the vicinity of the Almendro, Cambric, Dalhart, Cheshire, and Chancellor underground nuclear test locations range from <4 × 10-4 to 2.6 mBq/L (6 × 10-17–4.2 × 10-13 mol/L). All measured 237Np concentrations are well below the drinking water maximum contaminant level for alpha emitters identified by the U.S. EPA (560 mBq/L). Nevertheless, 237Np remains an important indicator for radionuclide transport rates atmore » the NNSS. Retardation factor ratios were used to compare the mobility of 237Np to that of other radionuclides. The results suggest that 237Np is less mobile than tritium and other non-sorbing radionuclides (14C, 36Cl, 99Tc and 129I) as expected. Surprisingly, 237Np and plutonium (239,240Pu) retardation factors are very similar. It is possible that Np(IV) exists under mildly reducing groundwater conditions and exhibits a retardation behavior that is comparable to Pu(IV). Independent of the underlying process, 237Np is migrating downgradient from NNSS underground nuclear tests at very low but measureable concentrations.« less

  10. Protactinium-231 Dating of Carbonates by Thermal Ionization Mass Spectrometry: Implications for Quaternary Climate Change

    PubMed

    Edwards; Cheng; Murrell; Goldstein

    1997-05-02

    Measurement of protactinium-231 (231Pa) in carbonates by thermal ionization mass spectroscopy yields 231Pa ages that are more than 10 times more precise than those determined by decay counting. Carbonates between 10 and 250,000 years old can now be dated with 231Pa methods. Barbados corals that have identical 231Pa and thorium-230 (230Th) ages indicate that the timing of sea level change over parts of the last glacial cycle is consistent with the predictions of the Astronomical Theory. Two Devils Hole calcite subsamples record identical 231Pa and 230Th ages, suggesting that the chronology of this climate record is accurate.

  11. Physical particularities of nuclear reactors using heavy moderators of neutrons

    SciTech Connect

    Kulikov, G. G. Shmelev, A. N.

    2016-12-15

    In nuclear reactors, thermal neutron spectra are formed using moderators with small atomic weights. For fast reactors, inserting such moderators in the core may create problems since they efficiently decelerate the neutrons. In order to form an intermediate neutron spectrum, it is preferable to employ neutron moderators with sufficiently large atomic weights, using {sup 233}U as a fissile nuclide and {sup 232}Th and {sup 231}Pa as fertile ones. The aim of the work is to investigate the properties of heavy neutron moderators and to assess their advantages. The analysis employs the JENDL-4.0 nuclear data library and the SCALE program package for simulating the variation of fuel composition caused by irradiation in the reactor. The following main results are obtained. By using heavy moderators with small neutron moderation steps, one is able to (1) increase the rate of resonance capture, so that the amount of fertile material in the fuel may be reduced while maintaining the breeding factor of the core; (2) use the vacant space for improving the fuel-element properties by adding inert, strong, and thermally conductive materials and by implementing dispersive fuel elements in which the fissile material is self-replenished and neutron multiplication remains stable during the process of fuel burnup; and (3) employ mixtures of different fertile materials with resonance capture cross sections in order to increase the resonance-lattice density and the probability of resonance neutron capture leading to formation of fissile material. The general conclusion is that, by forming an intermediate neutron spectrum with heavy neutron moderators, one can use the fuel more efficiently and improve nuclear safety.

  12. Physical particularities of nuclear reactors using heavy moderators of neutrons

    NASA Astrophysics Data System (ADS)

    Kulikov, G. G.; Shmelev, A. N.

    2016-12-01

    In nuclear reactors, thermal neutron spectra are formed using moderators with small atomic weights. For fast reactors, inserting such moderators in the core may create problems since they efficiently decelerate the neutrons. In order to form an intermediate neutron spectrum, it is preferable to employ neutron moderators with sufficiently large atomic weights, using 233U as a fissile nuclide and 232Th and 231Pa as fertile ones. The aim of the work is to investigate the properties of heavy neutron moderators and to assess their advantages. The analysis employs the JENDL-4.0 nuclear data library and the SCALE program package for simulating the variation of fuel composition caused by irradiation in the reactor. The following main results are obtained. By using heavy moderators with small neutron moderation steps, one is able to (1) increase the rate of resonance capture, so that the amount of fertile material in the fuel may be reduced while maintaining the breeding factor of the core; (2) use the vacant space for improving the fuel-element properties by adding inert, strong, and thermally conductive materials and by implementing dispersive fuel elements in which the fissile material is self-replenished and neutron multiplication remains stable during the process of fuel burnup; and (3) employ mixtures of different fertile materials with resonance capture cross sections in order to increase the resonance-lattice density and the probability of resonance neutron capture leading to formation of fissile material. The general conclusion is that, by forming an intermediate neutron spectrum with heavy neutron moderators, one can use the fuel more efficiently and improve nuclear safety.

  13. Field experiment determinations of distribution coefficients of actinide elements in alkaline lake environments

    SciTech Connect

    Simpson, H.J.; Trier, R.M.; Li, Y.-H.; Anderson, R.F.; Herczeg, A.L.

    1984-08-01

    Measurements of the radioisotope concentrations of a number of elements (Am, Pu, U, Pa, Th, Ac, Ra, Po, Pb, Cs, and Sr) in the water and sediments of a group of alkaline (pH = 9-10), saline lakes demonstrate greatly enhanced soluble-phase concentrations of elements with oxidation states of (III)-(VI) as the result of complexing by carbonate ion. Ratios of soluble radionuclide concentrations in Mono Lake to those in seawater ((CO/sub 3//sup 2 -/) in Mono Lake = 200 times that of seawater) were: Pu(approx. =10), /sup 238/U(approx. =150), /sup 231/Pa, /sup 228/Th, /sup 230/Th(approx. =10/sup 3/), and /sup 232/Th(approx. =10/sup 5/). Effective distribution coefficients of these radionuclides in high CO/sub 3//sup 2 -/ environments are several orders of magnitude lower (i.e., less particle reactive) than in most other natural waters. The importance of CO/sub 3//sup 2 -/ ion on effective K/sub d/ values was also strongly suggested by laboratory experiments in which most of the dissolved actinide elements became adsorbed to particles after a water sample normally at a pH of 10 was acidified, stripped of all CO/sub 2/, and then returned to pH 10 by adding NH/sub 4/OH. Furthermore, the effect of complexation by organic ligands is of secondary importance in the presence of appreciable carbonate ion concentration. Neither pure phase solubility calculations nor laboratory scale K/sub d/ determinations accurately predicted the measured natural system concentrations. Therefore, measurements of the distribution of radionuclides in natural systems are essential for assessment of the likely fate of potential releases from high level waste repositories to groundwater. 50 references, 31 figures, 43 tables.

  14. Inorganic, radioisotopic and organic analysis of 241-AP-101 tank waste

    SciTech Connect

    SK Fiskum; PR Bredt; JA Campbell; LR Greenwood; OT Farmer; GJ Lumetta; GM Mong; RT Ratner; CZ Soderquist; RG Swoboda; MW Urie; JJ Wagner

    2000-06-28

    Battelle received five samples from Hanford waste tank 241-AP-101, taken at five different depths within the tank. No visible solids or organic layer were observed in the individual samples. Individual sample densities were measured, then the five samples were mixed together to provide a single composite. The composite was homogenized and representative sub-samples taken for inorganic, radioisotopic, and organic analysis. All analyses were performed on triplicate sub-samples of the composite material. The sample composite did not contain visible solids or an organic layer. A subsample held at 10 C for seven days formed no visible solids. The characterization of the 241-AP-101 composite samples included: (1) Inductively-coupled plasma spectrometry for Ag, Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, K, La, Mg, Mn, Na, Nd, Ni, P, Pb, Pd, Ru, Rh, Si, Sr, Ti, U, Zn, and Zr (Note: Although not specified in the test plan, As, B, Be, Co, Li, Mo, Sb, Se, Sn, Tl, V, W, and Y were also measured and reported for information only) (2) Radioisotopic analyses for total alpha and total beta activities, {sup 3}H, {sup 14}C, {sup 60}Co, {sup 79}Se, {sup 90}Sr, {sup 99}Tc as pertechnetate, {sup 106}Ru/Rh, {sup 125}Sb, {sup 134}Cs, {sup 137}Cs, {sup 152}Eu, {sup 154}Eu, {sup 155}Eu, {sup 238}Pu, {sup 239+240}Pu, {sup 241}Am, {sup 242}Cm, and {sup 243+244}Cm; (3) Inductively-coupled plasma mass spectrometry for {sup 237}Np, {sup 239}Pu, {sup 240}Pu, {sup 99}Tc, {sup 126}Sn, {sup 129}I, {sup 231}Pa, {sup 233}U, {sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U, {sup 241}AMU, {sup 242}AMU, {sup 243}AMU, As, B, Be, Ce, Co, Cs, Eu, I, Li, Mo, Pr, Rb, Sb, Se, Ta, Te, Th, Tl, V, and W; (4) total U by kinetic phosphorescence analysis; (5) Ion chromatography for Cl, F, NO{sub 2}, NO{sub 3}, PO{sub 4}, SO{sub 4}, acetate, formate, oxalate, and citrate; (6) Density, inorganic carbon and organic carbon by two different methods, mercury, free hydroxide, ammonia, and cyanide. The 241-AP-101 composite met all

  15. Activity measurements of a suite of radionuclides (241Am, 239,240Pu, 238Pu, 238U, 234U, 235U, 232Th, 230Th, 228Th, 228Ra, 137Cs, 210Pb, 90Sr and 40K) in biota reference material (Ocean Shellfish): CCRI(II)-S3

    NASA Astrophysics Data System (ADS)

    Nour, S.; Karam, L. R.; Inn, K. G. W.

    2012-01-01

    In 2005, the CCRI decided that a comparison undertaken from 2002 to 2008 by the NIST (under the auspices of the Inter-America Metrology System [SIM]) in the development of a new biota (Ocean Shellfish) standard reference material (SRM) was sufficiently well constructed that it could be converted into a supplementary comparison under CCRI(II), with comparison identifier CCRI(II)-S3. This would enable the comparison to be used to support calibration and measurement capability (CMC) claims for radionuclide measurements in reference materials (specifically, animal-based organic materials). Previous comparisons of radionuclides have been of single or multiple nuclides in non-complex matrices and results of such could not be extended to support capabilities to measure the same nuclides in reference materials. The results of this comparison have been used to determine the certified reference value of the SRM. The key comparison working group (KCWG) of the CCRI(II) has approved this approach as a mechanism to link all the results to certified 'reference values' in lieu of the key comparison reference value (KCRV) of these specified radionuclides in this type of matrix (shellfish) so as to support CMCs of similar materials submitted by the present participants. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. SUPPLEMENTARY COMPARISON: Activity measurements of a suite of radionuclides (40K, 137Cs, 210Pb, 210Po, 228Ra, 232Th, 234U, 235U, 238U, 238Pu, 239Pu, 239+240Pu, 241Am) in vegetal reference material (seaweed)

    NASA Astrophysics Data System (ADS)

    Outola, I.; Inn, K. G. W.; Karam, L. R.

    2008-01-01

    In 2005, the CCRI decided that a comparison undertaken from 2002 to 2005 by the NIST (SIM) in the development of a new seaweed standard reference material (SRM) was sufficiently well constructed that it could be converted into a supplementary comparison under CCRI(II), with comparison identifier CCRI(II)-S1, so as to support calibration and measurement capability (CMC) claims for radionuclide measurements in reference material (specifically, plant material). Previous comparisons of radionuclides have been of single or multiple nuclides in non-complex matrices and results of such could not be extended to support capabilities to measure the same nuclides in reference materials. The results of this comparison have been reported to the participants, and were also used to determine the certified reference values of the SRM. The key comparison working group (KCWG) of the CCRI(II) has approved this approach as a mechanism to link all the results to the certified 'reference values' in lieu of the key comparison reference value (KCRV) of these specified radionuclides in this type of matrix (vegetative) so as to support CMCs of similar materials. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  17. Modeling report of the CEA cadarache MINERVE reactor for the OSMOSE project.

    SciTech Connect

    Klann, R.; Perret, G.; Hudelot, J. P.; Antony, M.

    2005-02-25

    The OSMOSE program (Oscillation in Minerve of isotopes in ''Eupraxic'' spectra) is a collaboration between the U.S. Department of Energy (DOE) and the Commissariat a l' Energie Atomique (CEA). It aims at measuring integral absorption rates of minor actinides by the oscillation technique in the MINERVE experimental facility located at the CEA Cadarache Research Center. The OSMOSE program also includes a complete analytical program to understand and resolve potential discrepancies between calculated and measured values. The OSMOSE program began in 2001 and will continue until 2013. The Argonne National Laboratory has developed Monte Carlo and deterministic calculation models of the MINERVE facility to determine core and safety parameters such as axial and radial fission rate distributions, control rod worth, spectral indices, and the reactivity worth of oscillated samples. Oscillation samples include calibration samples with different uranium enrichments and boron concentrations and the OSMOSE samples--separated actinides including {sup 232}Th, {sup 233}U, {sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U, {sup 237}Np, {sup 238}Pu, {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, {sup 242}Pu, {sup 241}Am, {sup 243}Am, {sup 244}Cm and {sup 245}Cm. Seven different neutron spectra will be created in the MINERVE facility: an overmoderated UO{sub 2} matrix (representative of a fuel processing plant or flooded storage cask), a UO{sub 2} matrix in water (representative of LWRs), a mixed oxide fuel matrix (representative of cores containing MOX fuels), two epithermal spectra (representative of under-moderated reactors), a moderated fast spectrum (representative of fast reactors which have some slowing down due to moderators such as lead-bismuth or sodium), and a very hard spectrum (representative of fast reactors with little moderation from reactor coolant). The different spectra are achieved by changing the experimental lattice within the MINERVE reactor. The currently investigated core

  18. The OSMOSE program for the qualification of integral cross sections of actinides: Preliminary results in a PWR-UOx spectrum

    SciTech Connect

    Hudelot, J. P.; Antony, M.; Bernard, D.; Fougeras, P.

    2006-07-01

    The need for improved nuclear data for minor actinides has been stressed by various organizations throughout the world - especially for studies relating to plutonium management, waste incineration, transmutation of waste, and Pu burning in future nuclear concepts. Several international programs have indicated a strong desire to obtain accurate integral reaction rate data for improving the major and minor actinides cross sections. Data on major actinides (i.e. {sup 235}U, {sup 236}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, {sup 242}Pu and {sup 241}Am) are reasonably well-known and available in the Evaluated Nuclear Data Files (JEFF, JENDL, ENDF-BX However information on the minor actinides (i.e. {sup 232}Th, {sup 233}U, {sup 237}Np, {sup 238}Pu, {sup 242}Am, {sup 243}Am, {sup 243}Cm, {sup 235}Cm, {sup 244}Cm, {sup 245}Cm, {sup 246}Cm and {sup 247}Cm) is less well-known and considered to be relatively poor in some cases, having to rely on model and extrapolation of few data points. In this framework, the ambitious OSMOSE program between the Commissariat a l'Energie Atomique (CEA), Electricite de France (EDF) and the U.S. Dept. of Energy (DOE) has been undertaken with the aim of measuring the integral absorption rate parameters of actinides in the MINERVE experimental facility located at the CEA Cadarache Research Center. The OSMOSE Program (Oscillation in Minerve of isotopes in 'Eupraxic' Spectra) includes a complete analytical program associated with the experimental measurement program and aims at understanding and resolving potential discrepancies between calculated and measured values. In the OSMOSE program, the reactivity worth of samples containing separated actinides are measured in different neutron spectra using an oscillation technique with an overall expected accuracy better than 3%. Reactivity effects of less than 10 pcm (0.0001 or approximately 1.5 cents) are measured and compared with calibrations to determine the differential reactivity

  19. Standardization of ²³⁷Np.

    PubMed

    Laureano-Perez, Lizbeth; Fitzgerald, R; Collé, R

    2014-05-01

    The standardization of (237)Np was investigated. The certified massic activity for (237)Np was obtained by 4παβ liquid scintillation (LS) counting with correction for the (233)Pa daughter using the CIEMAT/NIST efficiency tracing method using a (3)H standard. Confirmatory measurements were also performed by high-resolution HPGe gamma-ray spectrometry, and by 4παβ(LS)-γ(NaI) anticoincidence counting. All results agree within the respective method's uncertainties. It was confirmed that the (237)Np/(233)Pa radioactive equilibrium is disturbed when making dilutions and/or removing aliquots.

  20. Neptunium estimation in dissolver and high-level-waste solutions

    SciTech Connect

    Pathak, P.N.; Prabhu, D.R.; Kanekar, A.S.; Manchanda, V.K.

    2008-07-01

    This papers deals with the optimization of the experimental conditions for the estimation of {sup 237}Np in spent-fuel dissolver/high-level waste solutions using thenoyltrifluoroacetone as the extractant. (authors)

  1. Nuclear Criticality Safety of the DOT 9975 Container for237NpO2Storage, Handling, and Transport

    SciTech Connect

    Reed, D.A.

    2003-08-29

    Nuclear criticality safety considerations are presented to address use of the DOT 9975 shipping container for {sup 237}NpO{sub 2}. The DOT 9975 container will be used by multiple DOE sites and contractors. Various of site- and activity-specific NCS and facility safety documents are yet to be developed. For these reasons, an overall assessment of criticality safety of {sup 237}NpO{sub 2}-loaded DOT 9975 containers is considered useful to personnel involved in generating, reviewing, or approving these various documents. It is concluded that inherent container features, the loading per container (maximum of 6 kg {sup 237}Np), and the nuclear physics properties of {sup 237}NpO{sub 2} combine to preclude the potential for a nuclear criticality accident. This conclusion applies to storage, handling, and transport operations involving closed DOT 9975 packages, including credible off-normal conditions that may result in damage to packages during those operations.

  2. Analysis of trace neptunium in the vicinity of underground nuclear tests at the Nevada National Security Site.

    PubMed

    Zhao, P; Tinnacher, R M; Zavarin, M; Kersting, A B

    2014-11-01

    A high sensitivity analytical method for (237)Np analysis was developed and applied to groundwater samples from the Nevada National Security Site (NNSS) using short-lived (239)Np as a yield tracer and HR magnetic sector ICP-MS. The (237)Np concentrations in the vicinity of the Almendro, Cambric, Dalhart, Cheshire, and Chancellor underground nuclear test locations range from <4 × 10(-4) to 2.6 mBq/L (6 × 10(-17)-4.2 × 10(-13) mol/L). All measured (237)Np concentrations are well below the drinking water maximum contaminant level for alpha emitters identified by the U.S. EPA (560 mBq/L). Nevertheless, (237)Np remains an important indicator for radionuclide transport rates at the NNSS. Retardation factor ratios were used to compare the mobility of (237)Np to that of other radionuclides. The results suggest that (237)Np is less mobile than tritium and other non-sorbing radionuclides ((14)C, (36)Cl, (99)Tc and (129)I) as expected. Surprisingly, (237)Np and plutonium ((239,240)Pu) retardation factors are very similar. It is possible that Np(IV) exists under mildly reducing groundwater conditions and exhibits a retardation behavior that is comparable to Pu(IV). Independent of the underlying process, (237)Np is migrating downgradient from NNSS underground nuclear tests at very low but measureable concentrations. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. Determination of Np-237 by radiochemical neutron activation analysis combined with extraction chromatography.

    PubMed

    Kalmykov, St N; Aliev, R A; Sapozhnikov, D Yu; Sapozhnikov, Yu A; Afinogenov, A M

    2004-01-01

    A procedure for determination of 237Np, 238Pu, 239,240Pu and 241Pu in environmental samples is described. Neptunium-237 is determined using radiochemical neutron activation analysis with pre- and post-irradiation chemistry based on solvent extraction and extraction chromatography. 238Pu, 239,240Pu is determined using alpha spectrometry and 241Pu by liquid scintillation spectrometry. The vertical profiles of 237Np, 238Pu, 239,240Pu in bottom sediments from the Black Sea are presented.

  4. Temporal variation and provenance of thorium deposition observed at Tsukuba, Japan.

    PubMed

    Hirose, Katsumi; Kikawada, Yoshikazu; Igarashi, Yasuhito

    2012-06-01

    Temporal variations of monthly thorium (Th) deposition observed at Tsukuba, Japan during the period 1990-2007, comparing with plutonium deposition, was studied. The monthly (232)Th deposition as did (239,240)Pu, varied according to season and inter-annually. In particular, (232)Th deposition increased significantly in spring coinciding with Asian dust (Kosa) events. The (230)Th/(232)Th activity ratios vary according to sources and can therefore be used to differentiate between locally derived and remotely derived (232)Th. The (230)Th/(232)Th activity ratios in deposition samples showed large variability with high ratios occurring in early spring. These high (230)Th/(232)Th ratios in deposition can be attributed to local dust storms, especially in early spring, that cause resuspension of soils from cultivated fields which are characterized by high (230)Th/(232)Th activity ratios. The results reveal that both locally and remotely derived (232)Th deposition showed seasonal variations with maxima in spring, although the remotely derived fraction is dominant rather than the locally derived one. The (232)Th deposition maxima later in spring is attributable to the remotely derived fraction, corresponding to the Kosa events. Annual (232)Th deposition exhibited an increasing trend, suggesting the presence of sources other than soil dust such as fly ash from increasing coal burning.

  5. High-Precision Th-Pb Dating by Isotope-Dilution TIMS+MC-ICPMS - Preliminary Results

    NASA Astrophysics Data System (ADS)

    Ickert, R. B.; Mundil, R.; Sharp, W. D.

    2014-12-01

    Relative to the U-Pb decay series, the Th-Pb decay series has received relatively little attention for geochronology although it offers promising applications in both high-resolution geochronology as well as thermochronology. The limitations are partly because Th measurements by thermal ionization have proven notoriously difficult, and for many geochronological applications, the additional information provided by Th-Pb has not been worth the effort required. However, the current generation of MC-ICPMS instruments provides nearly two orders of magnitude better sensitivity of Th than TIMS, eliminating this barrier to measurement and opening up this chronometer for new use. We have developed a method to measure relative abundances of Th, U and Pb by isotope dilution for high-precision geochronology. This method leverages the strengths of two instruments, the high sensitivity and stable mass fractionation of MC-ICPMS instruments for Th and U, and the low background, lack of isobaric interference, and signal stability of TIMS instruments for Pb. To make these measurements, we have calibrated a new synthetic isotope tracer that comprises a mixture of 229Th-233U-236U-202Pb-205Pb. The analytical strategy developed for accessory minerals is a hybrid of techniques previously developed for U-Pb ID-TIMS and U/230Th ID-MC-ICPMS, with a two-column HCl-HNO3 anion exchange procedure (one to separate U and Pb from matrix+Th, and the other to separate Th from matrix), followed by a recombination of the U and Th fractions for MC-ICPMS analysis while the Pb fraction is measured by TIMS. Th-Pb measurements are complementary to, and potentially as precise as the U-Pb gold standard, and the method will find application in certain geological problems, including (1) precisely determining the relative decay rates of 232Th and 238U, (2) dating materials that are young enough to be substantially affected by 230Th or 231Pa disequilibria, and (3) dating small quantities of high-Th minerals like

  6. No iron fertilization in the equatorial Pacific Ocean during the last ice age

    NASA Astrophysics Data System (ADS)

    Costa, K. M.; McManus, J. F.; Anderson, R. F.; Ren, H.; Sigman, D. M.; Winckler, G.; Fleisher, M. Q.; Marcantonio, F.; Ravelo, A. C.

    2016-01-01

    The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron. Greater atmospheric dust deposition could have fertilized the equatorial Pacific with iron during the last ice age—the Last Glacial Period (LGP)—but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the 232Th proxy), phytoplankton productivity (using opal, 231Pa/230Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ15N) from six cores in the central equatorial Pacific for the Holocene (0-10,000 years ago) and the LGP (17,000-27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region. Thus, ice-age iron fertilization in the

  7. No iron fertilization in the equatorial Pacific Ocean during the last ice age.

    PubMed

    Costa, K M; McManus, J F; Anderson, R F; Ren, H; Sigman, D M; Winckler, G; Fleisher, M Q; Marcantonio, F; Ravelo, A C

    2016-01-28

    The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron. Greater atmospheric dust deposition could have fertilized the equatorial Pacific with iron during the last ice age--the Last Glacial Period (LGP)--but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the (232)Th proxy), phytoplankton productivity (using opal, (231)Pa/(230)Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ(15)N) from six cores in the central equatorial Pacific for the Holocene (0-10,000 years ago) and the LGP (17,000-27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region. Thus, ice-age iron fertilization in the

  8. Rates of carbonate soil evolution from carbon, U- and Th-series isotope studies: Example of the Astian sands (SE France)

    NASA Astrophysics Data System (ADS)

    Barbecot, Florent; Ghaleb, Bassam; Hillaire-Marcel, Claude

    2015-04-01

    In carbonate rich soils, C-isotopes (14C, 13C) and carbonate mass budget may inform on centennial to millennial time scale dissolution/precipitation processes and weathering rates, whereas disequilibria between in the U- and Th-decay series provide tools to document high- (228Ra-228Th-210Pb) to low- (234U, 230Th, 231Pa, 226Ra) geochemical processes rate, covering annual to ~ 1Ma time scales, governing both carbonate and silicate soil fractions. Because lithology constitutes a boundary condition, we intend to illustrate the behavior of such isotopes in soils developed over Astian sands formation (up to ~ 30% carbonate) from the Béziers area (SE France). A >20 m thick unsaturated zone was sampled firstly along a naturally exposed section, then in a cored sequence. Geochemical and mineralogical analyses, including stable isotopes and 14C-measurements, were complemented with 228U, 234U, 230Th, 226Ra, 210Pb and 228Th, 232Th measurements. Whereas the upper 7 m depict geochemical and isotopic features forced by dissolution/precipitation processes leading to variable radioactive disequilibria, but overall deficits in more soluble elements of the decay series, the lower part of the sequence shows strong excesses in 234U and 230Th over parent isotopes (i.e., 238U and 234U, respectively). These features might have been interpreted as the result of successive phases of U-loss and gains. However, 226Ra and 230Th are in near-equilibrium, thus leading to conclude at a more likely slow enrichment process in both 234Th(234U) and 230Th, which we link to dissolved U-decay during groundwater recharge events. In addition, 210Pb deficits (vs parent 226Ra) are observed down to 12 m along the natural outcropping section and below the top-soil 210Pb-excess in the cored sequence, due to gaseous 222Rn-diffusion over the cliff outcrop. Based on C-isotope and chemical analysis, reaction rates at 14C-time scale are distinct from those estimates at the short- or long-lived U-series isotopes

  9. Corrigendum to "Deep water provenance and dynamics of the (de)glacial Atlantic meridional overturning circulation" [Earth Planet. Sci. Lett. 445 (2016) 68-78

    NASA Astrophysics Data System (ADS)

    Lippold, Jörg; Gutjahr, Marcus; Blaser, Patrick; Christner, Emanuel; de Carvalho Ferreira, Maria Luiza; Mulitza, Stefan; Christl, Marcus; Wombacher, Frank; Böhm, Evelyn; Antz, Benny; Cartapanis, Olivier; Vogel, Hendrik; Jaccard, Samuel L.

    2017-01-01

    We have reconstructed past modes of the Atlantic Meridional Overturning Circulation (AMOC) by combining two sedimentary proxies, Nd isotopes (εNd) and the 231Pa/230Th ratio over the last deglaciation. Combined down-core 231Pa/230Th and εNd records from six Atlantic Ocean sediment archives are presented (Lippold et al., 2016).

  10. Protactinium-231 dating of carbonates by thermal ionization mass spectrometry: Implications for quaternary climate change

    SciTech Connect

    Edwards, R.L.; Cheng, H.; Murrell, M.T.; Goldstein, S.J.

    1997-05-02

    Measurement of protactinium-231 ({sup 231}Pa) in carbonates by thermal ionization mass spectroscopy yields {sup 231}Pa ages that are more than 10 times more precise than those determined by decay counting. Carbonates between 10 and 250,000 years old can now be dated with {sup 231}Pa methods. Barbados corals that have identical {sup 231}Pa and thorium-230 ({sup 230}Th) ages indicate that the timing of sea level change over parts of the last glacial cycle is consistent with the predictions of the Astronomical Theory. Two Devils Hole calcite subsamples record identical {sup 231}Pa and {sup 230}Th ages, suggesting that the chronology of this climate record is accurate. 24 refs., 4 figs., 1 tab.

  11. Neptunium Transport Behavior in the Vicinity of Underground Nuclear Tests at the Nevada Test Site

    SciTech Connect

    Zhao, P; Tinnacher, R M; Zavarin, M; Williams, R W; Kersting, A B

    2010-12-03

    We used short lived {sup 239}Np as a yield tracer and state of the art magnetic sector ICP-MS to measure ultra low levels of {sup 237}Np in a number of 'hot wells' at the Nevada National Security Site (NNSS), formerly known as the Nevada Test Site (NTS). The results indicate that {sup 237}Np concentrations at the Almendro, Cambric, Dalhart, Cheshire and Chancellor sites, are in the range of 3 x 10{sup -5} to 7 x 10{sup -2} pCi/L and well below the MCL for alpha emitting radionuclides (15 pCi/L) (EPA, 2009). Thus, while Np transport is believed to occur at the NNSS, activities are expected to be well below the regulatory limits for alpha-emitting radionuclides. We also compared {sup 237}Np concentration data to other radionuclides, including tritium, {sup 14}C, {sup 36}Cl, {sup 99}Tc, {sup 129}I, and plutonium, to evaluate the relative {sup 237}Np transport behavior. Based on isotope ratios relative to published unclassified Radiologic Source Terms (Bowen et al., 1999) and taking into consideration radionuclide distribution between melt glass, rubble and groundwater (IAEA, 1998), {sup 237}Np appears to be substantially less mobile than tritium and other non-sorbing radionuclides, as expected. However, this analysis also suggests that {sup 237}Np mobility is surprisingly similar to that of plutonium. The similar transport behavior of Np and Pu can be explained by one of two possibilities: (1) Np(IV) and Pu(IV) oxidation states dominate under mildly reducing NNSS groundwater conditions resulting in similar transport behavior or (2) apparent Np transport is the result of transport of its parent {sup 241}Pu and {sup 241}Am isotopes and subsequent decay to {sup 237}Np. Finally, measured {sup 237}Np concentrations were compared to recent Hydrologic Source Term (HST) models. The 237Np data collected from three wells in Frenchman Flat (RNM-1, RNM-2S, and UE-5n) are in good agreement with recent HST transport model predictions (Carle et al., 2005). The agreement provides

  12. Criticality of a Neptunium-237 sphere surrounded with highly enriched uranium shells and an iron reflector

    SciTech Connect

    Sanchez, R. G.; Loaiza, D. J.; Hayes, D. K.; Kimpland, R. H.

    2004-01-01

    An additional experiment has been performed using the recently cast 6-kg {sup 237}Np sphere. The experiment consisted of surrounding the neptunium sphere with highly enriched uranium and an iron reflector. The purpose of the critical experiment is to provide additional criticality data that can be used to validate criticality safety evaluations involving the deposition of neptunium. It is well known that {sup 237}Np is primarily produced by successive neutron capture events in {sup 235}U or through the (n, 2n) reaction in {sup 238}U. These nuclear reactions lead to the production of {sup 237}U, which decays by beta emission into {sup 237}Np. In addition, in the spent fuel, {sup 241}Am decays by alpha emission into {sup 237}Np. Because {sup 237}Np is a threshold fissioner, the best reflectors for critical systems containing neptunium are those materials that exhibit good neutron scattering properties such as low carbon steel (99 wt % Fe). In this experiment, the iron reflector reduced the amount of uranium used in the critical experiment and increased the importance of the neptunium sphere.

  13. Studies of Np and Pu in the marine environment of Swedish-Danish waters and the North Atlantic Ocean.

    PubMed

    Lindahl, Patric; Roos, Per; Holm, Elis; Dahlgaard, Henning

    2005-01-01

    The long-lived anthropogenic radionuclides (237)Np, (239)Pu and (240)Pu were determined in marine environmental samples (seaweed and seawater) collected from Swedish-Danish waters and the North Atlantic Ocean at various locations on different occasions during the period 1991-2001. The measurements were performed with sector field Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and conventional alpha spectrometry. The (237)Np activity concentrations in Fucus vesiculosus and surface seawater from the Swedish west coast and Danish waters ranged from 0.16+/-0.02 to 1.02+/-0.09 mBq kg(-1) (dry weight) and 0.65+/-0.02 to 1.69+/-0.02 mBq m(-3), respectively, depending on the location and sampling year. Most of the (237)Np in these waters is believed to originate from the Sellafield nuclear reprocessing plant, with some contribution from global fallout. The (240)Pu/(239)Pu atomic ratios in F. vesiculosus samples are reported in this study with an overall average of 0.17+/-0.03. The (237)Np and (239)Pu activity concentrations observed in surface seawater collected in North Atlantic waters ranged from 0.16+/-0.01 to 0.62+/-0.08 mBq m(-3) and from 0.64+/-0.05 to 4.27+/-0.08 mBq m(-3), respectively, and the (237)Np/(239)Pu atomic ratios were a good indicator of conservative behaviour of Np in marine waters.

  14. Prompt Fission Neutron Spectra of Actinides

    SciTech Connect

    Capote, R; Chen, Y J; Hambsch, F J; Kornilov, N V; Lestone, J P; Litaize, O; Morillon, B; Neudecker, D; Oberstedt, S; Ohsawa, T; Smith, D. L.

    2016-01-01

    The energy spectrum of prompt neutrons emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) “Evaluation of Prompt Fission Neutron Spectra of Actinides”was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei. The following technical areas were addressed: (i) experiments and uncertainty quantification (UQ): New data for neutron-induced fission of 233U, 235U, 238U, and 239Pu have been measured, and older data have been compiled and reassessed. There is evidence from the experimental work of this CRP that a very small percentage of neutrons emitted in fission are actually scission neutrons; (ii) modeling: The Los Alamos model (LAM) continues to be the workhorse for PFNS evaluations. Monte Carlo models have been developed that describe the fission phenomena microscopically, but further development is needed to produce PFNS evaluations meeting the uncertainty targets; (iii) evaluation methodologies: PFNS evaluations rely on the use of the least-squares techniques for merging experimental and model data. Considerable insight was achieved on how to deal with the problem of too small uncertainties in PFNS evaluations. The importance of considering that all experimental PFNS data are “shape” data was stressed; (iv) PFNS evaluations: New evaluations, including covariance data, were generated for major actinides including 1) non-model GMA evaluations of the 235U(nth,f), 239Pu(nth,f), and 233U(nth,f) PFNS based exclusively on experimental data (0.02 ≤ E ≤ 10 MeV), which resulted in PFNS average energies E of 2.00±0.01, 2.073±0.010, and 2.030±0.013 MeV, respectively; 2) LAM evaluations of neutron-induced fission spectra on uranium and plutonium targets with improved UQ for incident energies from thermal up to 30 MeV; and 3) Point-by-Point calculations for 232Th, 234U and 237Np targets; and (v) data

  15. Subcellular localization of neptunium-237 in lung and kidney after intratracheal administration in the rat: an ultrastructural and microanalytical study.

    PubMed

    Boulahdour, H; Poncy, J L; Berry, J P; Galle, P

    1996-12-01

    Chronic intratracheal administration of 237Np to rate was performed during 6 weeks. The total dose administered was 45.8 kBq. Two methods, electron microscopy and electron probe X-ray microanalysis, were used to determine the intracellular sites of localization of 237Np. Clusters of dense granules were observed in nuclei of pneumocytes and proximal tubular cells of the kidneys. These clusters have been shown to contain neptunium associated with phosphorus, sulfur and calcium. Alterations of nuclei and ultrastructural cytoplasmic lesions were observed. The absorbed doses in lungs and kidneys were very low. These results suggest that the chemical toxicity of 237Np is more important than its radiological toxicity.

  16. Resonance ionization mass spectroscopy for trace analysis of neptunium

    NASA Astrophysics Data System (ADS)

    Riegel, J.; Deißenberger, R.; Herrmann, G.; Köhler, S.; Sattelberger, P.; Trautmann, N.; Wendeler, H.; Ames, F.; Kluge, H.-J.; Scheerer, F.; Urban, F.-J.

    1993-05-01

    Resonance ionization mass spectroscopic (RIMS) measurements for trace analysis and spectroscopy of 237Np, the ecologically most important isotope of neptunium, are described. The chemical procedure for the separation of neptunium from aqueous samples as well as the preparation of filaments for RIMS are outlined. Several two- and three-step excitation schemes have been investigated in order to find suitable conditions for the sensitive detection of 237Np. Using a three-step, three-color excitation and ionization scheme an overall detection efficiency of 3×10-8 was obtained, resulting in a detection limit of 4×108 atoms (160 fg) of 237Np. The hyperfine structure splittings of the levels under investigation, which influence the detection limit, were measured. A new method to determine the first ionization potential (IP) was applied to neptunium yielding a value of IP=6.2655(2) eV.

  17. Thorium-induced neurobehavioural and neurochemical alterations in Swiss mice.

    PubMed

    Kumar, Amit; Ali, Manjoor; Mishra, Pravin; Pandey, B N; Sharma, Pragya; Mishra, Kaushala Prasad

    2009-04-01

    Thorium ((232)Th), a heavy metal radionuclide that targets the liver and skeleton, has been shown to accumulate in the central nervous system at low levels. The present study was aimed to investigate neurobehavioural and neurochemical changes in mice treated with (232)Th at sub-lethal doses. Swiss albino mice were administered intraperitoneally with thorium nitrate. The chelation-based therapeutic effect of calcium diethylenetriamine pentaacetate (Ca-DTPA) was tested on the (232)Th-treated mice. (232)Th localisation was determined in brain regions by the Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) method. Achetylcholine esterase (AChE) activity in different brain regions was evaluated to assess the cholinergic function of mice CNS. Oxidative damage was evaluated by assessing the activities of antioxidant enzymes (i.e., superoxide dismutase and catalase) and the level of lipid peroxidation. The neurobehavioural alteration in the treated mice was studied by the shuttle box method. (232)Th accumulation found in different brain regions followed the order: Cerebellum (Cbl) > cortex (Ctx) > hippocampus (Hp) > striatum (Str). However, removal of (232)Th by Ca-DTPA was significant from brain regions like Cbl, Ctx and Str but not from Hp. A significant increase in lipid peroxidation and acetylcholine esterase (AChE) activity was observed in the treated mice but activities of superoxide dismutase and catalase was found substantially decreased. (232)Th treatment impaired the learning and memory-based neurobehaviour of the mice. Furthermore, our data suggest that Ca-DTPA injection in (232)Th-treated animals failed to improve the neurobehaviour of the treated mice, perhaps because Ca-DTPA could not decorporate (232)Th or mitigate (232)Th-mediated neurochemical changes effectively from/in hippocampus, a brain region implicated in learning and memory response. Administration of (232)Th in mice caused neurobehavioural alteration and impairment of cholinergic

  18. Validation of Cross Sections with Criticality Experiment and Reaction Rates: the Neptunium Case

    NASA Astrophysics Data System (ADS)

    Leong, L. S.; Tassan-Got, L.; Audouin, L.; Berthier, B.; Le Naour, C.; Stéphan, C.; Paradela, C.; Tarrío, D.; Duran, I.

    2014-04-01

    The 237Np neutron-induced fission cross section has been recently measured in a large energy range (from eV to GeV) at the n_TOF facility at CERN. When compared to previous measurements the n_TOF fission cross section appears to be higher by 5-7% beyond the fission threshold. To check the relevance of the n_TOF data, we considered a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np, surrounded by uranium highly enriched in 235U so as to approach criticality with fast neutrons. The multiplication factor keff of the calculation is in better agreement with the experiment when we replace the ENDF/B-VII.0 evaluation of the 237Np fission cross section by the n_TOF data. We also explored the hypothesis of deficiencies of the inelastic cross section in 235U which has been invoked by some authors to explain the deviation of 750 pcm. The large modification needed to reduce the deviation seems to be incompatible with existing inelastic cross section measurements. Also we show that the νbar of 237Np can hardly be incriminated because of the high accuracy of the existing data. Fission rate ratios or averaged fission cross sections measured in several fast neutron fields seem to give contradictory results on the validation of the 237Np cross section but at least one of the benchmark experiments, where the active deposits have been well calibrated for the number of atoms, favors the n_TOF data set. These outcomes support the hypothesis of a higher fission cross section of 237Np.

  19. Criticality experiments and benchmarks for cross section evaluation: the neptunium case

    NASA Astrophysics Data System (ADS)

    Leong, L. S.; Tassan-Got, L.; Audouin, L.; Paradela, C.; Wilson, J. N.; Tarrio, D.; Berthier, B.; Duran, I.; Le Naour, C.; Stéphan, C.

    2013-03-01

    The 237Np neutron-induced fission cross section has been recently measured in a large energy range (from eV to GeV) at the n_TOF facility at CERN. When compared to previous measurement the n_TOF fission cross section appears to be higher by 5-7% beyond the fission threshold. To check the relevance of n_TOF data, we apply a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np, surrounded by enriched uranium 235U so as to approach criticality with fast neutrons. The multiplication factor ke f f of the calculation is in better agreement with the experiment (the deviation of 750 pcm is reduced to 250 pcm) when we replace the ENDF/B-VII.0 evaluation of the 237Np fission cross section by the n_TOF data. We also explore the hypothesis of deficiencies of the inelastic cross section in 235U which has been invoked by some authors to explain the deviation of 750 pcm. With compare to inelastic large distortion calculation, it is incompatible with existing measurements. Also we show that the v of 237Np can hardly be incriminated because of the high accuracy of the existing data. Fission rate ratios or averaged fission cross sections measured in several fast neutron fields seem to give contradictory results on the validation of the 237Np cross section but at least one of the benchmark experiments, where the active deposits have been well calibrated for the number of atoms, favors the n_TOF data set. These outcomes support the hypothesis of a higher fission cross section of 237Np.

  20. Determination of femtogram quantities of protactinium in geologic samples by thermal ionization mass spectrometry

    SciTech Connect

    Pickett, D.A.; Murrell, M.T.; Williams, R.W. )

    1994-04-01

    We describe a procedure for measurement of [sup 231]Pa in geologic samples by isotope dilution thermal ionization mass spectrometry, using [sup 233]Pa as a spike isotope, which provides marked improvements in precision and sample size relative to established decay counting techniques. This method allows determination of as little as a few tens of femtograms of [sup 231]Pa (approximately 10[sup 3] atoms) with a conservative estimated uncertainty of [+-]1% (95% confidence level). Applications of [sup 231]Pa-[sup 235]U systematics to uranium-series geochemistry and geochronology should be greatly enhanced by this approach. 31 refs., 4 figs., 1 tab.

  1. Distribution of neptunium and plutonium in New Mexico lichen samples (Usnea arizonica) contaminated by atmospheric fallout

    DOE PAGES

    Oldham, Jr., Warren J.; Hanson, Susan K.; Lavelle, Kevin B.; ...

    2015-08-30

    In this study, the concentrations of 237Np, 239Pu and 240Pu were determined in lichen samples (Usnea arizonica) that were collected from ten locations in New Mexico between 2011 and 2013 using isotope dilution inductively-coupled plasma mass spectrometry (ID-ICP-MS). The observed isotopic ratios for 237Np/239Pu and 240Pu/239Pu indicate trace contamination from global and regional fallout (e.g. Trinity test and atmospheric testing at the Nevada Test Site). The fact that actinide contamination is detected in recent lichen collections suggests continuous re-suspension of fallout radionuclides even 50 years after ratification of the Limited Test Ban Treaty.

  2. Ultrastructural apoptotic lesions induced in bone marrow after neptunium-237 contamination.

    PubMed

    Pusset, D; Boulahdour, H; Fromm, M; Poncy, J L; Kantelip, B; Griffond, B; Baud, M; Galle, P

    2003-01-01

    This study describes the ultrastructure of lesions induced by neptunium-237 (237Np), a by-product of uranium in nuclear reactors, in the bone marrow. A group of rats were given a single injection of 237Np-nitrate solution in order to observe the acute toxicity effects of this actinide. Electron microscopy was used to describe the different lesions. Observations included the swelling of the cell membrane, nuclear membrane lyses, abnormal chromatin condensation or nucleus convolution. These ultrastructural alterations of the nucleus and the cellular membrane appeared shortly after treatment. This study demonstrates the toxic effects of neptunium and its implication in the induction of apoptosis in bone marrow.

  3. Transport of neptunium through Yucca Mountain tuffs

    SciTech Connect

    Triay, I.R.; Robinson, B.A.; Mitchell, A.J.; Overly, C.M.; Lopez, R.M.

    1993-02-01

    Neptunium has a high solubility in groundwaters from Yucca Mountain [1]. Uranium in nuclear reactors produces {sup 237}Np which has a half-life of 2.1 4 {times} 10{sup 6} years. Consequently, the transport of {sup 237}Np through tuffs is of major importance in assessing the performance of a high-level nuclear waste repository at Yucca Mountain. The objective of this work is to determine the amount of Np retardation that is provided by the minerals in Yucca Mountain tuffs as a function of groundwater chemistry.

  4. Subcellular and intranuclear localization of neptunium-237 (V) in rat liver.

    PubMed

    Paquet, F; Verry, M; Grillon, G; Landesman, C; Masse, R; Taylor, D M

    1995-08-01

    The present investigation was aimed at establishing the distribution of 237Np within the different structures of hepatocytes. Rats were contaminated experimentally by intravenous injection of 237Np (V) and the subcellular structures of the liver were separated by ultracentrifugation. Twenty-four hours after contamination, the nuclear and cytosolic fractions bound 54 and 32%, respectively, of the total radionuclide. Purification of the nuclei followed by dissociation of the protein components in medium of increasing ionic strength showed a specific binding of neptunium to the structural proteins of the nuclear matrix.

  5. The properties of 235Np as a tracer and yield monitor in studies of the environmental behaviour of neptunium

    NASA Astrophysics Data System (ADS)

    Harvey, B. R.; Sutton, G. A.

    1987-02-01

    The production, detection and decay scheme of 235Np are discussed with reference to the potential application of this nuclide as a tracer and alternative yield monitor for the analysis of 237Np in environmental materials. Improved detection efficiency, which results from assay by counting the L X-ray emissions on an Si(Li) detector, is shown to reduce substantially the problem caused by contamination of the tracer by 237Np. A most important use for 235Np is seen to be in the study of the oxidation states of neptunium in the environment.

  6. Accelerator mass spectrometry of the planetary elements

    NASA Astrophysics Data System (ADS)

    Fifield, L. K.; Clacher, A. P.; Morris, K.; King, S. J.; Cresswell, R. G.; Day, J. P.; Livens, F. R.

    1997-03-01

    Accelerator mass spectrometry has been applied for the first time to the detection of 237Np. Sensitivity approaches 105 atoms. A first measurement of the mobility of 237Np in a marine environment is reported, and lends support to the prediction that neptunium should be substantially more mobile than plutonium. Measurements of backgrounds and transmissions for plutonium and neptunium in different charge states are also reported. In addition, the relative negative ion formation probabilities for the monoxide ions of Th, U, Np and Pu have been measured.

  7. Alpha-induced reaction cross-section for Sm, U, Np targets: influence of hexadecapole deformation and deformed surface diffuseness

    NASA Astrophysics Data System (ADS)

    Alavi, S. A.; Dehghani, V.

    2017-06-01

    Alpha-induced reactions on 154Sm, 233,235,236,238U, and 237Np deformed nuclei are studied theoretically. The effects of hexadecapole deformation, deformed surface diffuseness parameter, and orientation on barrier height and position, fusion cross-section at any angle, and fusion cross-section have been investigated. Both hexadecapole deformation and deformed surface diffuseness can affect barrier characteristics and enhance fusion cross-section. Good agreement between experimental data and theoretical calculations with quadrupole and hexadecapole deformation and deformed surface diffuseness were observed for the 4He+154Sm, 235U, 237Np reactions.

  8. Application of ICP-MS for the assessment of thorium excretion in urine.

    PubMed

    Roth, P; Werner, E; Wendler, I; Schramel, P

    1996-01-01

    A method for rapid and sensitive determination of thorium in urine by inductively coupled plasma mass spectometry (ICP-MS) is described. The method is sufficiently sensitive to detect 1 ng/L 232Th in urine without any sample preparation. The mean urinary 232Th excretion in 23 unexposed subjects was 6.2 +/- 3.3 ng/d.

  9. Thorium isotopes in autopsy samples from thorium workers

    SciTech Connect

    Stehney, A.F.; Lucas, H.F.

    2000-01-01

    Concentrations of {sup 232}Th and activity ratios of {sup 228}Th to {sup 232}Th and {sup 230}Th to {sup 232}Th were determined in autopsy samples from five former employees of a thorium refinery. The ranges of {sup 232}Th activity concentrations (mBq per gram of wet tissue) were 0.17--94 in lungs, 3.9--1,210 in pulmonary lymph nodes, 0.14--1.19 in bones, 0.015--0.68 in liver, 0.97--5.8 in spleen, and 0.009--0.068 in kidneys. These concentrations are 10 to 1,000 times greater than have been reported for persons not occupationally exposed to thorium. In most of the samples, the ratios of {sup 228}Th to {sup 232}Th and {sup 232}Th to {sup 232}Th activity at death of the subject were 0.2--0.4 and 0.1--0.2, respectively. {sup 228}Th to {sup 228}Ra activity ratios ({+-} standard errors) of 0.86 {+-} 0.11 in lungs and 1.18 {+-} 0.13 in lymph nodes of one subject were obtained by calculation from ratios of {sup 228}Th to {sup 232}Th.

  10. 10 CFR 110.22 - General license for the export of source material.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... country not listed in § 110.28: (1) Uranium or thorium, other than U-230, U-232, Th-227, and Th-228, in any substance in concentrations of less than 0.05 percent by weight. (2) Thorium, other than Th-227... thorium, other than U-230, U-232, Th-227, or Th-228, in individual shipments of 10 kilograms or less...

  11. Protactinium-thorium ratio as a proxy for ocean circulation

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2011-12-01

    The Atlantic meridional overturning circulation (AMOC) transports water and heat over long distances in the Atlantic Ocean and is believed to have an important effect on Earth's climate. Knowing how strong the AMOC was in the past is essential to understanding past climate. One proxy researchers have used to assess the past strength of the AMOC is the sedimentary protactinium- thorium ratio (231Pa/230Th). Both 231Pa and 230Th are produced through decay of uranium at a constant rate in the ocean water column, but 230Th does not last long enough in the water to be transported away from the location where it was produced, while 231Pa has a longer residence time in the water. Therefore, sedimentary 231Pa/230Th ratios could provide information about the strength of past ocean circulation.

  12. Actinide neutron induced cross-sections; analysis of the OSMOSE LWR-UO{sub 2} experiment in MINERVE

    SciTech Connect

    Bernard, D.; Litaize, O.; Santamarina, A.; Antony, M.; Hudelot, J. P.

    2006-07-01

    This paper describes the interpretation of the first phase of the OSMOSE experimental program. The OSMOSE experiment began in 2005 in the MINERVE French facility and will continue until 2008. It consists in reactivity worth measurements of separated actinides by an oscillation technique. First results are obtained in a standard LWR neutron spectrum (UO{sub 2} lattice). The present study focuses on the following isotopes: {sup 234,236}U, {sup 237}Np, {sup 239,242}Pu. The comparison between APOLLO2 accurate deterministic calculations and experiments shows the reliability of the latest JEFF-3.1 European nuclear data library for all oscillated isotopes, except {sup 237}Np. The obtained (C/E-1){+-}({delta}E/E) values are the following: {sup 234}U: -5%{+-}2% {sup 237}Np: -11%{+-}2% {sup 239}Pu: +1%{+-}2% {sup 242}Pu: +2%{+-}2% An energetic decomposition of the reactivity worth is carried out using Standard Perturbation Theory that underlines the underestimation of the {sup 237}Np(n, {gamma}) thermal and resonant capture cross-section. (authors)

  13. Neptunium separations

    SciTech Connect

    Wild, J.F.

    1983-05-09

    Two procedures for the separation of Np are presented; the first involves separation of /sup 239/Np from irradiated /sup 238/U, and the second involves separation of /sup 237/Np from a solution representing that from a dissolved fuel element.

  14. Metabolic studies of neptunium in the adult baboon: retention, distribution, kinetics, and enhanced excretion by chelation therapy. Technical progress report summary

    SciTech Connect

    Not Available

    1984-01-01

    These investigations provided additional data on the uptake, distribution, retention and excretion of Np-237, Np-239 and Pa-233 in baboons following single intravenous or gavage administration. The influence of oxidation state, chemical medium, pH, mass, etc. on the metabolism of these radionuclides is related.

  15. Thorium isotopes in human tissues

    SciTech Connect

    Stehney, A.F.; Lucas, H.F.

    1991-12-31

    Concentrations of {sup 232}Th and activity ratios of {sup 228}Th to {sup 232}Th and {sup 230}Th to {sup 232}Th were determined in autopsy samples from five former employees of a thorium refinery. The ranges of {sup 232}Th activity concentrations (mBq g{sup {minus}1}) were 0.17--94 in lungs, 3.9--1210 in pulmonary lymph nodes, 0.14--1.19 in bones, 0.015--0.68 in liver, 0.97--5.8 in spleen, and 0.009--0.068 in kidneys. These concentrations are 10 to 1000 times greater than have been reported for persons not occupationally exposed to Th. In most of the samples, the ratios of {sup 230}Th to {sup 232}Th and {sup 228}Th to {sup 232}Th activity at death of the subject were 0.1--0.2 and 0.2--0.4, respectively. Thorium-228 to {sup 228}Ra activity ratios ({plus_minus} standard errors) of 0.86 {plus_minus} 0.11 in lungs and 1.18 {plus_minus} 0.13 in lymph nodes of one subject were obtained by calculation from ratios of {sup 228}Th to {sup 232}Th.

  16. Sequential injection approach for simultaneous determination of ultratrace plutonium and neptunium in urine with accelerator mass spectrometry.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Roos, Per; Lachner, Johannes; Christl, Marcus; Xu, Yihong

    2013-09-17

    An analytical method was developed for simultaneous determination of ultratrace level plutonium (Pu) and neptunium (Np) using iron hydroxide coprecipitation in combination with automated sequential injection extraction chromatography separation and accelerator mass spectrometry (AMS) measurement. Several experimental parameters affecting the analytical performance were investigated and compared including sample preboiling operation, aging time, amount of coprecipitating reagent, reagent for pH adjustment, sedimentation time, and organic matter decomposition approach. The overall analytical results show that preboiling and aging are important for obtaining high chemical yields for both Pu and Np, which is possibly related to the aggregation and adsorption behavior of organic substances contained in urine. Although the optimal condition for Np and Pu simultaneous determination requires 5-day aging time, an immediate coprecipitation without preboiling and aging could also provide fairly satisfactory chemical yields for both Np and Pu (50-60%) with high sample throughput (4 h/sample). Within the developed method, (242)Pu was exploited as chemical yield tracer for both Pu and Np isotopes. (242)Pu was also used as a spike in the AMS measurement for quantification of (239)Pu and (237)Np concentrations. The results show that, under the optimal experimental condition, the chemical yields of (237)Np and (242)Pu are nearly identical, indicating the high feasibility of (242)Pu as a nonisotopic tracer for (237)Np determination in real urine samples. The analytical method was validated by analysis of a number of urine samples spiked with different levels of (237)Np and (239)Pu. The measured values of (237)Np and (239)Pu by AMS exhibit good agreement (R(2) ≥ 0.955) with the spiked ones confirming the reliability of the proposed method.

  17. Characterization of contaminant transport using naturally-occurring U-series disequilibria. 1998 annual progress report

    SciTech Connect

    Murrell, M.; Ku, T.L.

    1998-06-01

    'The goal of the research is to study the migratory behavior of contaminants in subsurface fractured systems using naturally occurring uranium- and thorium-series radionuclides as tracers under in-situ physico-chemical and hydrogeologic conditions. Naturally occurring U- and Th-series disequilibria can provide information on the rates of adsorption-desorption and transport of contaminants as well as on fluid transport and rock dissolution in a natural setting. The authors are developing a realistic model of contaminant migration in the Snake River Plain Aquifer beneath the INEEL by evaluating the retardation processes involved in the rock/water interaction. The major tasks are to: (1) determine the natural distribution of U, Th, Pa and Ra isotopes in the groundwater as well as in rock minerals and sorbed phases, and (2) study rock/water interaction processes using U/Th series disequilibria and a statistical analysis-based model code for the calculation of in-situ retardation factors of radionuclides and rock/water interaction time scales. This study will also provide an improved understanding of the hydrogeologic features of the site and their impact on the migration of contaminants. This report summarizes results after 20 months of a 36-month project. Studies performed at LANL include analysis of the long-lived nuclides {sup 238}U, {sup 235}U, {sup 234}U, {sup 230}Th, {sup 226}Ra, {sup 232}Th, and {sup 231}Pa by thermal ionization mass spectrometry (TIMS). Studies performed at the Univ. of Southern California include the measurement of short-lived naturally occurring radionuclides by decay-counting techniques and the development of models to predict the migration behavior of these radionuclides. Initial efforts began with analysis of 31, 0.5L water samples obtained through routine sampling by USGS and INEEL personnel. One significant observation from these data is that {sup 234}U/{sup 238}U activity ratios are highest in waters that emanate from local recharge

  18. Comparisons between thorium isotopes in seawater and marine sediments for reconstructing dissolved and total detrital inputs to the ocean

    NASA Astrophysics Data System (ADS)

    Hsieh, Y.; Henderson, G. M.; Williams, R. H.; McGee, D.

    2012-12-01

    Thorium-232, the most abundant Th isotope in the continental crust, has been widely used in seawater and marine sediments to evaluate continental inputs to the ocean. Seawater 232Th concentrations combined with estimates of Th residence time in the surface ocean derived from measurements of 230Th (or 234Th or 228Th) have been used to assess the dissolved 232Th removal flux. Assuming a constant 232Th concentration in detritus and dust Th solubility in seawater, 232Th removal flux can be converted to atmospheric dust input to the ocean. In marine sediments, 232Th concentrations have been normalized by 230Th to estimate total 232Th sinking flux to the seafloor. Similarly, this flux can also be used to estimate dust input to the ocean. Comparisons between dissolved 232Th removal flux in seawater and total 232Th sinking flux in sediments are crucial, because the discrepancy between these two fluxes could provide insights into several important issues, including uncertain dust Th solubility, potential advective Th inputs, inaccurate 230Th-derived sediment accumulation rates, and unknown lateral sediment transport. However, comparisons between these two fluxes have rarely been made in the same core-top sediments and water columns above. In this study, we compile several seawater and marine sediment Th data from different regions of the ocean, with a focus on the tropical North Atlantic Ocean. The data are used to estimate 232Th removal and sinking fluxes, and hence the dissolved and total detrital inputs to the ocean. The results are also compared with other dust tracers (e.g. Al and Ti) and modeled dust deposition to improve our understanding of Th and dust in the ocean. This work offers an important test for the use of Th isotopes in reconstructing paleo dust input to the ocean and the impacts of dust flux changes on marine productivity and climate change in the past.

  19. Extraction of protactinium-233 and separation from thermal neutron-irradiated thorium-232 using crown ethers

    SciTech Connect

    Jalhoom, Moayyed G.; Mohammed, Dawood A.; Khalaf, Jumah S.

    2008-07-01

    A new method was developed for the extraction and separation of {sup 233}Pa from thermal neutron-irradiated {sup 232}Th. Solutions of Pa{sup 233} were prepared in LiCI-HCl solutions from which appreciable extraction was obtained using dibenzo-18-crown-6 in 1,2-dichloroethane. The effects of cavity size, substitutions on the crown ring, type of the organic solvent, and temperature on extraction are discussed. Very high separation factors were obtained for the pairs {sup 233}Pa/{sup 232}Th (>105), {sup 233}Pa/{sup 233}U (> 1000), and {sup 232}U/{sup 232}Th (>60). (authors)

  20. Interactions of secondary particles with thorium samples in the setup QUINTA irradiated with 6 GeV deuterons

    NASA Astrophysics Data System (ADS)

    Khushvaktov, J.; Adam, J.; Baldin, A. A.; Chilap, V. V.; Furman, V. I.; Sagimbaeva, F.; Solnyshkin, A. A.; Stegailov, V. I.; Tichy, P.; Tsoupko-Sitnikov, V. M.; Tyutyunnikov, S. I.; Vespalec, R.; Vrzalova, J.; Yuldashev, B. S.; Wagner, V.; Zavorka, L.; Zeman, M.

    2016-08-01

    The natural uranium assembly, QUINTA, was irradiated with 6 GeV deuterons. The 232Th samples were placed at the central axis of the setup QUINTA. The spectra of gamma rays emitted by the activated 232Th samples have been analysed and more than one hundred nuclei produced have been identified. For each of those products, reaction rates have been determined. The ratio of the weight of produced 233U to 232Th is presented. Experimental results were compared with the results of Monte Carlo simulations by FLUKA code.

  1. Natural radioactivity content of granite tiles used in Greece.

    PubMed

    Papaefthymiou, H

    2008-01-01

    Measurements of (226)Ra, (232)Th and (40)K activity concentrations in commercial granite tiles imported in Greece were performed using gamma-ray spectrometry. The activity concentration of (226)Ra, (232)Th and (40)K ranged from 1 to 434, 2 to 239 and 71 to 1576 Bq kg(-1), respectively. The calculated activity concentration index (I) values for all granite samples examined were found to be within the EC limit values for superficial and other materials with restricted use.

  2. Determination of thorium in seawater by neutron activation analysis and mass spectrometry

    SciTech Connect

    Huh, Chih-An

    1987-01-01

    The recent development of neutron activation analysis and mass spectrometric methods for the determination of /sup 232/Th in seawater has made possible rapid sampling and analysis of this long-lived, non-radiogenic thorium isotope on small-volume samples. The marine geochemical utility of /sup 232/Th, whose concentration in seawater is extremely low, warrants the development of these sensitive techniques. The analytical methods and some results are presented and discussed in this article. 24 refs., 3 figs.

  3. Melting of the Earth's lithospheric mantle inferred from protactinium-thorium-uranium isotopic data

    PubMed

    Asmerom; Cheng; Thomas; Hirschmann; Edwards

    2000-07-20

    The processes responsible for the generation of partial melt in the Earth's lithospheric mantle and the movement of this melt to the Earth's surface remain enigmatic, owing to the perceived difficulties in generating large-degree partial melts at depth and in transporting small-degree melts through a static lithosphere. Here we present a method of placing constraints on melting in the lithospheric mantle using 231Pa-235U data obtained from continental basalts in the southwestern United States and Mexico. Combined with 230Th-238U data, the 231Pa-235U data allow us to constrain the source mineralogy and thus the depth of melting of these basalts. Our analysis indicates that it is possible to transport small melt fractions--of the order of 0.1%--through the lithosphere, as might result from the coalescence of melt by compaction owing to melting-induced deformation. The large observed 231Pa excesses require that the timescale of melt generation and transport within the lithosphere is small compared to the half-life of 231Pa (approximately 32.7 kyr). The 231Pa-230Th data also constrain the thorium and uranium distribution coefficients for clinopyroxene in the source regions of these basalts to be within 2% of one another, indicating that in this setting 230Th excesses are not expected during melting at depths shallower than 85 km.

  4. Optimization of small long-life PWR based on thorium fuel

    NASA Astrophysics Data System (ADS)

    Subkhi, Moh Nurul; Suud, Zaki; Waris, Abdul; Permana, Sidik

    2015-09-01

    A conceptual design of small long-life Pressurized Water Reactor (PWR) using thorium fuel has been investigated in neutronic aspect. The cell-burn up calculations were performed by PIJ SRAC code using nuclear data library based on JENDL 3.2, while the multi-energy-group diffusion calculations were optimized in three-dimension X-Y-Z geometry of core by COREBN. The excess reactivity of thorium nitride with ZIRLO cladding is considered during 5 years of burnup without refueling. Optimization of 350 MWe long life PWR based on 5% 233U & 2.8% 231Pa, 6% 233U & 2.8% 231Pa and 7% 233U & 6% 231Pa give low excess reactivity.

  5. Optimization of small long-life PWR based on thorium fuel

    SciTech Connect

    Subkhi, Moh Nurul; Suud, Zaki Waris, Abdul; Permana, Sidik

    2015-09-30

    A conceptual design of small long-life Pressurized Water Reactor (PWR) using thorium fuel has been investigated in neutronic aspect. The cell-burn up calculations were performed by PIJ SRAC code using nuclear data library based on JENDL 3.2, while the multi-energy-group diffusion calculations were optimized in three-dimension X-Y-Z geometry of core by COREBN. The excess reactivity of thorium nitride with ZIRLO cladding is considered during 5 years of burnup without refueling. Optimization of 350 MWe long life PWR based on 5% {sup 233}U & 2.8% {sup 231}Pa, 6% {sup 233}U & 2.8% {sup 231}Pa and 7% {sup 233}U & 6% {sup 231}Pa give low excess reactivity.

  6. Ultrastructural lesions induced by neptunium-237: apoptosis or necrosis?

    PubMed

    Pusset, D; Fromm, M; Poncy, J L; Kantelip, B; Galle, P; Chambaudet, A; Baud, M; Boulahdour, H

    2002-07-01

    In this study, we are concerned with the 237 isotope of neptunium (237Np), which is a by-product of uranium in nuclear reactors. To study ultrastructural lesions induced by this element, a group of rats were injected with a solution of 237Np-nitrate once a day for 14 weeks. Lesions observed in liver and kidney are described using electron microscopy. Ultrastructural alterations of cellular membranes and intracellular organelles demonstrated the existence of neptunium toxicity. This toxicity was characterized by various lesions, such as cytoplasmic clarification, disappearance of mitochondrial cristae, swollen mitochondria, abnormal condensation of nuclear chromatin, and nuclear fragmentations. This study demonstrated the probable induction of apoptosis by neptunium both in liver and kidneys.

  7. Entry to neptunyl(V) chemistry in anhydrous systems

    SciTech Connect

    Copping, Roy; Berthon, Claude; Moisy, Philippe; Den Auwer, Christophe

    2012-08-15

    The increasing generation of highly radioactive neptunium during nuclear power production has called for an enhanced understanding of the fundamental chemistry of this element. NpO{sub 2}{sup +}, Np(V) is the most relevant neptunyl species in both nuclear reprocessing, environmental concerns and long-term storage of waste where {sup 237}Np represents a significant component of radiotoxicity. A fundamental understanding of the structure, bonding and reactivity of this species is essential for the development of advanced future {sup 237}Np separation processes. Therefore it is important that neptunyl(V) coordination chemistry is advanced to anaerobic systems where air and moisture sensitive ligands containing softer donor atoms can be utilized. To achieve this we have developed an anhydrous Np(V) synthetic precursor and begun to probe coordination chemistry with multi-dentate Schiff base ligands. (authors)

  8. Standardization of 241Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting.

    PubMed

    Balpardo, C; Capoulat, M E; Rodrigues, D; Arenillas, P

    2010-01-01

    The nuclide (241)Am decays by alpha emission to (237)Np. Most of the decays (84.6%) populate the excited level of (237)Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of (241)Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

  9. Delayed neutron emission measurements from fast fission of U-235 and Np-237

    SciTech Connect

    Charlton, W.S.; Parish, T.A.; Raman, S.; Shinohara, Nubuo; Andoh, Masaki

    1996-09-01

    Experiments have been designed and conducted to measure the periods and yields of delayed neutrons from fast fission of {sup 235}U and {sup 237}Np. These measurements were performed in a pool type reactor using a fast flux in-core irradiation device. The energy dependent neutron flux spectrum within the irradiation device was characterized using a foil activation technique and the SAND-II unfolding code. Five delayed neutron groups were measured. The total yield (sum of the five group yields) for {sup 235}U was found to be 0.0141 {+-} 0. 0009. The total yield for {sup 237}Np was found to be 0.0102 {+-} 0. 0008. The total delayed neutron yield data were found to be in good agreement with previous measurements. The individual group yields reported here are preliminary and are being further refined.

  10. Neptunium-237 inhalation in rats.

    PubMed

    Sullivan, M F; Ruemmler, P S; Buschbom, R L

    1986-12-01

    Groups of rats were exposed to aerosols of 237Np nitrate to determine clearance rates, retention and distribution at various intervals after inhalation. Initial lung burdens (ILB) after 237Np inhalation by three treatment groups were 0.12, 0.19 and 0.37 mu Ci/kg, respectively. Radiochemical analyses of animals killed at 4, 8, 14, 28 and 90 d, as well as data for others maintained until they became moribund, showed that their lung clearance followed a three-compartment model, clearance half-times for which were 1, 35, and 10,000 d, respectively. Only 3% of the ILB was retained after 90 d; 12% of that burden had translocated to the skeleton at 750 d; the half-time for skeletal retention was 2500 d. A single tumor was the only malignancy detected in the lungs of the 35 animals allowed to survive the early phase of the study.

  11. The Geochemical Behaviour of Tc, Np, and Pu in Spent Nuclear Fuel in an Oxidizing Environment

    SciTech Connect

    Buck, Edgar C.; Hanson, Brady D.; McNamara, Bruce K.; R. Giere and P. Stille

    2004-10-01

    Studies at the Nopal and Shinkolowbwe uranium deposits show that the primary uraninite (UO2) altered to a suite of secondary uranyl minerals similar to those observed in corrosion tests with uranium oxide . Although the Nopal I deposit tells us something about the possible fate of uranium, it tells us little about the likely fate of the important long-lived radionuclides; iodine (129I), cesium (135Cs), technetium (99Tc), neptunium (237Np), and plutonium (239Pu). Most performance assessment (PA) models, assume conservatively, that as the UO2 matrix corrodes, the key radionuclides (129I, 99Tc, 237Np, and 239Pu) will be released congruently. In so doing, these PA models force increased reliance on human engineered barriers.

  12. Protactinium neutron-induced fission up to 200 MeV

    NASA Astrophysics Data System (ADS)

    Maslov, V.

    2010-03-01

    The theoretical evaluation of 230-233Pa(n,F) cross sections is based on direct data, 230-234Pa fission probabilities and ratios of fission probabilities in first-chance and emissive fission domains, surrogate for neutroninduced fission. First chance fission cross sections trends of Pa are based on consistent description of 232Th(n,F), 232Th(n,2n) and 238U(n,F), 238U(n,xn) data, supported by the ratio surrogate data by Burke et al., 2006, for the 237U(n,F) reaction. Ratio surrogate data on fission probabilities of 232Th(6 Li,4 He)234Pa and 232 Th(6 Li,d)236U by Nayak et al., 2008, support the predicted 233Pa(n, F) cross section at En=11.5-16.5 MeV. The predicted trends of 230-232Pa(n, F) cross section up to En=20 MeV, are consistent with fissilities of Pa nuclides, extracted by 232Th(p,F) (Isaev et al., 2008) and 232Th(p,3n) (Morgenstern et al., 2008) data analysis. The excitation energy and nucleon composition dependence of the transition from asymmetric to symmetric scission for fission observables of Pa nuclei is defined by analysis of p-induced fission of 232Th at Ep=1-200 MeV. Predominantly symmetric fission in 232Th(p,F) at En( p)=200 MeV as revealed by experimental branching ratios (Dujvestijn et al., 1999) is reproduced. Steep transition from asymmetric to symmetric fission with increase of nucleon incident energy is due to fission of neutron-deficient Pa (A≤229) nuclei. A structure of the potential energy surface (a drop of f f symmetric and asymmetric fission barriers difierence (EfSYM - EfASYM) from ~3.5 MeV to ~1 MeV) of N-deficient Pa nuclides (A≤226) and available phase space at outer fission saddles, are shown to be responsible for the sharp increase with En( p) of the symmetric fission component contribution for 232Th(p,F) and 230-233 Pa(n, F) reactions. That is a strong evidence of emissive fission nature of moderately excited Pa nuclides, reliably quantified only up to En( p)~20(30) MeV. Predicted fission cross section of 232Pa(n,F) coincides

  13. Structural variability in neptunium(V) oxalate compounds: synthesis and structural characterization of Na2NpO2(C2O4)OH.H2O.

    PubMed

    Bean, Amanda C; Garcia, Eduardo; Scott, Brian L; Runde, Wolfgang

    2004-10-04

    Reaction of a (237)Np(V) stock solution in the presence of oxalic acid, calcium chloride, and sodium hydroxide under hydrothermal conditions produces single crystals of a neptunium(V) oxalate, Na(2)NpO(2)(C(2)O(4))OH.H(2)O. The structure consists of one-dimensional chains running down the a axis and is the first example of a neptunium(V) oxalate compound containing hydroxide anions.

  14. Magnetic sublattices in Np2Co17 and Np2Ni17

    NASA Astrophysics Data System (ADS)

    Colineau, E.; Hen, A.; Sanchez, J.-P.; Griveau, J.-C.; Magnani, N.; Eloirdi, R.; Halevy, I.; Gaczyński, P.; Orion, I.; Shick, A. B.; Caciuffo, R.

    2016-12-01

    Rare-earth-based compounds R2T17 (R=Rare earth; T=Transition metal) have been extensively studied and developed for applications as permanent magnets. The actinide-based analogues, however, are much less documented and we report here about the magnetic properties of Np2Co17 and Np2Ni17, as inferred from 237Np Mössbauer spectroscopy, the best resonance in actinides, and specific heat.

  15. American National Standard: for nuclear criticality control of special actinide elements

    SciTech Connect

    Not Available

    1981-01-01

    This standard is applicable to operations with the following: /sup 237/Np, /sup 238/Pu, /sup 240/Pu, /sup 241/Pu, /sup 242/Pu, /sup 241/Am, /sup 242m/Am, /sup 243/Am, /sup 243/Cm, /sup 244/Cm, /sup 245/Cm, /sup 247/Cm, /sup 249/Cf and /sup 251/Cf. Subcritical mass limits are presented for isolated fissionable units. The limits are not applicable to interacting units.

  16. Experimental study on neptunium migration under in situ geochemical conditions

    NASA Astrophysics Data System (ADS)

    Kumata, M.; Vandergraaf, T. T.

    1998-12-01

    Results are reported for migration experiments performed with Np under in situ geochemical conditions over a range of groundwater flow rates in columns of crushed rock in a specially designed facility at the 240-level of the Underground Research Laboratory (URL) near Pinawa, Manitoba, Canada. This laboratory is situated in an intrusive granitic rock formation, the Lac du Bonnet batholith. Highly altered granitic rock and groundwater were obtained from a major subhorizontal fracture zone at a depth of 250 m in the URL. The granite was wet-crushed and wet-sieved with groundwater from this fracture zone. The 180-850-μm size fraction was selected and packed in 20-cm long, 2.54-cm in diameter Teflon™-lined stainless steel columns. Approximately 30-ml vols of groundwater containing 3HHO and 237Np were injected into the columns at flow rates of 0.3, 1, and 3 ml/h, followed by elution with groundwater, obtained from the subhorizontal fracture, at the same flow rates, for a period of 95 days. Elution profiles for 3HHO were obtained, but no 237Np was detected in the eluted groundwater. After terminating the migration experiments, the columns were frozen, the column material was removed and cut into twenty 1-cm thick sections and each section was analyzed by gamma spectrometry. Profiles of 237Np were obtained for the three columns. A one-dimensional transport model was fitted to the 3HHO breakthrough curves to obtain flow parameters for this experiment. These flow parameters were in turn applied to the 237Np concentration profiles in the columns to produce sorption and dispersion coefficients for Np. The results show a strong dependence of retardation factors ( Rf) on flow rate. The decrease in the retarded velocity of the neptunium ( Vn) varied over one order of magnitude under the geochemical conditions for these experiments.

  17. Electron paramagnetic resonance and electron nuclear double resonance of 237-neptunium hexafluoride in uranium hexafluoride single crystals

    NASA Astrophysics Data System (ADS)

    Butler, James E.; Hutchison, Clyde A., Jr.

    1981-03-01

    The EPR and ENDOR spectra of 237NpF6 molecules dilutely substituted for host molecules in single crystals of UF6 at temperatures between 1.2 and 2.1 °K have been obtained at microwave frequencies, ˜9.4 and ˜9.7 GHz. Approximate values are given for the parameters in a spin Hamiltonian formalism that describes the measurements. The results are discussed.

  18. Systematic trends in the237neptunium Mössbauer isomer shift: Overlap of IV, V and VI neptunium oxidation states and correlation between isomer shift and crystal structure

    NASA Astrophysics Data System (ADS)

    Jové, J.; Cousson, A.; Abazli, H.; Tabuteau, A.; Thévenin, T.; Pagès, M.

    1988-01-01

    The influence of the neptunium ion environment on the237Np Mössbauer isomer shifts has been studied in various metal coordination complexes: fluorides, oxides, oxide fluorides and polycarboxylates. A linear dependence between the isomer shift and the mean neptunium-ligand distance in a series of hexavalent Np compounds has been evidenced and the feasibility of overlapped isomer shift areas, namely Np(IV), Np(V) and Np(VI) has been established.

  19. The Study on the Migration of Radionuclides in the Shallow Land

    SciTech Connect

    Li, S.; Wang, Z.; Li, Z.; Zhao Y.; Guo, Z.; Guo, L.; Shi, Y.; Ogawa, H.; Maeda, T.; Matsumoto, J.; Mukai, M.; Tanaka, T.

    2002-02-25

    >From 1995 through 2001 a cooperative study project on the migration of radionuclides in shallow land was carried out by CIRP and JAERI, which covers field test, laboratory simulation test, other laboratory studies and related model development. The radionuclides studied involve 90Sr, 237Np, 238Pu. For comparison the nonradioactive elements Sr, Nd and Ce were also studied. The field test was performed both in aerated zone and aquifer zone of loess. In the aerated zone the nuclide migration in engineering materials were also studied. The study in the aerated zone was carried out in 9 pits with the size of 2m x 2m under natural conditions or artificial sprinkling conditions. The study in the aquifer was carried out in a new built Underground Research Facility with the area of 142m2. The test results show that the order of adsorption activity of the nuclide on the loess is 238Pu > 237Np > 90Sr and Nd, Ce > Sr. During the 3 years period of test the migration of 238Pu and Nd, Ce was not observable in both aerated zone and aquifer zone, the nuclide of 237Np migrated a small distance, and the nuclide of 90Sr had a relative large migration. The migration of the nuclides in engineering materials was not detected, which include cement, degraded cement, cement mortar, Chinese bentonite and Japanese bentonite.

  20. Method for determination of neptunium in large-sized urine samples using manganese dioxide coprecipitation and 242Pu as yield tracer.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Roos, Per

    2013-02-05

    A novel method for bioassay of large volumes of human urine samples using manganese dioxide coprecipitation for preconcentration was developed for rapid determination of (237)Np. (242)Pu was utilized as a nonisotopic tracer to monitor the chemical yield of (237)Np. A sequential injection extraction chromatographic (SI-EC) system coupled with inductively coupled plasma mass spectrometry (ICPMS) was exploited to facilitate the rapid column separation and quantification. The analytical results demonstrated satisfactory performance of the MnO(2) coprecipitation as indicated by the high chemical yields close to 100% and high separation capacity of processing up to 5 L of human urine samples. The MnO(2) coprecipitation process is simple and straightforward in which a batch (8-12) of samples can be pretreated within 4 h (i.e., <0.5 h/sample). In connection with the automated column separation and ICPMS quantification, which takes less than 1.5 h in total, the overall analytical time was on average less than 2 h for each sample. The high effectiveness and sample throughput make the developed method well suited for urine bioassay of (237)Np in routine monitoring of occupationally internal radiation exposure and rapid analysis of neptunium contamination level for emergency preparedness.

  1. The effect of the mass and initial chemical form of neptunium on its molecular associations in blood and liver.

    PubMed

    Paquet, F; Ramounet, B; Métivier, H; Taylor, D M

    1996-09-01

    The present investigation was aimed at establishing the distribution of neptunium in blood and liver cells as a function of the mass and chemical form of the radionuclide injected. Four groups of rats received intravenous injections of 237Np(V), 237Np(IV), 239Np(V) or 239Np(IV). Twenty-four hours after injection of the radionuclide, subcellular structures of the liver were separated by ultracentrifugation and serum and liver cytosol were subjected to gel permeation chromatography. The intracellular distribution of neptunium in liver depends on the mass of the radionuclide injected; the relative specific activity for 237Np compared to 239Np was 2 in nuclei and 0.5-0.9 in cytosol. By contrast, the initial chemical form of the radionuclide has no significant effect on its intracellular distribution. In cytosol, neptunium was bound mainly by two proteins of molecular weight 450 and 200 kDa, respectively. The former was identified as ferritin, but the latter remains unidentified. In this compartment, no effect of mass or chemical form was seen. In blood, the bulk of the radionuclide was bound to transferrin whatever the mass and initial chemical form injected.

  2. Further studies on the influence of chemical form and dose on absorptions of Np, Pu, Am and Cm from the gastrointestinal tracts of adult and neonatal rodents.

    PubMed

    Sullivan, M F; Miller, B M; Ruemmler, P S; Ryan, J L

    1985-01-01

    Absorption of isotopes of the actinide elements Np, Pu, Am and Cm from various organic media and/or in combination with plant or animal ligands or tissue is compared with their absorption from an inorganic nitrate medium. Gastrointestinal (GI) transport of 238Pu, 239Pu, 241Am and 244Cm at high concentrations from citrate medium by adult rats and/or mice was higher than from nitric acid medium. Neptunium-237 absorption, however, was not increased by citrate; probably because its oxidation state was reduced from 237Np(V) to 237Np(IV) by the medium and by the GI content. Increasing the mass of the 237Np dose resulted in increased absorption. Neither incorporation of 238Pu in rat liver nor retention of 238Pu oxide in rat lungs enhanced absorption when those Pu-containing tissues were administered intragastrically to either adult or neonatal rats. Ranking of GI absorption of the various forms of Pu gavaged in these studies suggests that transport is in the order: Pu citrate greater than Pu phytate greater than biologically incorporated Pu greater than Pu nitrate.

  3. The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range

    SciTech Connect

    Basunia, M. S.; Clark, R. M.; Goldblum, B. L.; Bernstein, L. A.; Phair, L.; Burke, J. T.; Beausang, C. W.; Bleuel, D. L.; Darakchieva, B.; Dietrich, F. S.; Evtimova, M.; Fallon, P.; Gibelin, J.; Hatarik, R.; Jewett, C. C.; Lesher, S. R.; McMahan, M. A.; Rodriguez-Vieitez, E.; Wiedeking, M.

    2009-02-25

    The surrogate reaction 238U(3He,tf) is used to determine the 237Np(n,f) cross section indirectly over an equivalent neutron energy range from 10 to 20 MeV. A self-supporting ~;;761 mu g/cm2 metallic 238U foil was bombarded with a 42 MeV 3He2+ beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Outgoing charged particles and fission fragments were identified using the Silicon Telescope Array for Reaction Studies (STARS), consists of two 140 mu m and one 1000 mu m Micron S2 type silicon detectors. The 237Np(n,f) cross sections, determined indirectly, were compared with the 237Np(n,f) cross section data from direct measurements, the Evaluated Nuclear Data File (ENDF/B-VII.0), and the Japanese Evaluated Nuclear Data Library (JENDL 3.3) and found to closely follow those datasets. Use of the (3He,tf) reaction as a surrogate to extract (n,f) cross section in the 10 to 20 MeV equivalent neutron energy is found to be suitable.

  4. High-sensitivity fast neutron detector KNK-2-7M

    SciTech Connect

    Koshelev, A. S. Dovbysh, L. Ye.; Ovchinnikov, M. A.; Pikulina, G. N.; Drozdov, Yu. M.; Chuklyaev, S. V.

    2015-12-15

    The construction of the fast neutron detector KNK-2-7M is briefly described. The results of the study of the detector in the pulse-counting mode are given for the fissions of {sup 237}Np nuclei in the radiator of the neutron-sensitive section and in the current mode with the separation of sectional currents of functional sections. The possibilities of determining the effective number of {sup 237}Np nuclei in the radiator of the neutronsensitive section are considered. The diagnostic possibilities of the detector in the counting mode are shown by example of the analysis of the reference data from the neutron-field characteristics in the working hall of the BR-K1 reactor. The diagnostic possibilities of the detector in the current operating mode are shown by example of the results of measuring the {sup 237}Np-fission intensity in the BR-K1 reactor power start-ups implemented in the mode of fission-pulse generation on delayed neutrons at the detector arrangement inside the reactor core cavity under conditions of a wide variation of the reactor radiation field.

  5. Thorium distributions in high- and low-dust regions and the significance for iron supply

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher T.; Rosen, Jeffrey; McGee, David; Boyle, Edward A.

    2017-02-01

    Thorium and uranium isotopes (232Th, 230Th, 238U, and 234U) were investigated to refine their use for estimating mineral dust deposition and Fe delivery to the ocean. U concentrations and isotope ratios were consistent with conservative behavior and can safely be described using published U-salinity relationships and global average seawater isotopic composition. Near Barbados, waters affected by the Amazon outflow contained elevated 232Th. This signals one region where the thorium-dust method is inaccurate because of a confounding continental input. Dissolved 232Th fluxes in this region suggest that Amazonian Fe supply to the adjacent open ocean is much larger than local atmospheric deposition. The colloidal content of dissolved Th south of Bermuda was found to be quite small (2-6%), similar to that found north of Hawaii, despite the order of magnitude higher dust deposition in the Atlantic. This finding supports the assumption that dissolved 232Th and 230Th are scavenged at the same rate despite their different sources and also sheds light on the increase of dissolved 232Th fluxes with integrated depth. Outside the region influenced by Amazon River waters, dissolved 232Th fluxes are compared with Bermudan aerosol Fe deposition to estimate that fractional Th solubility is around 20% in this region. Finally, new dissolved and soluble Fe, Mn, and Cr data from the subtropical North Pacific support the idea that Fe concentrations in the remote ocean are highly buffered, whereas 232Th has a larger dynamic range between high- and low-dust regions.

  6. Decorporation and therapeutic efficacy of liposomal-DTPA against thorium-induced toxicity in the Wistar rat.

    PubMed

    Kumar, Amit; Sharma, Pragya; Ali, Manjoor; Pandey, Badri Narain; Mishra, Kaushala Prasad

    2012-03-01

    This study examined the effect of liposomal encapsulation of (99m)Tc-labeled diethylenetriaminepentaacetic acid (metastable technetium labeled DTPA) on its organ distribution and therapeutic effect of optimized neutral liposomal-DTPA against thorium ((232)Th)-induced liver toxicity and its accumulation in rat animal model. (99m)Tc-DTPA was encapsulated in neutral (dipalmitoylphosphatidylcholine:cholesterol) and positively (dipalmitoylphosphatidylcholine:cholesterol:stearylamine) charged liposomes using thin film hydration method. Comparative efficacy of liposomal and free DTPA (11.2 mg/kg) was examined in terms of its effect on (232)Th accumulation and subsequent toxicity in the liver and blood of rat administered with (232)Th-nitrate (600 μg/kg). Organ distribution of free or liposomal (99m)Tc-DTPA was determined by solid scintillation counting and (232)Th accumulation by Inductively Coupled Plasma-Atomic Emission Spectroscopy. Neutral liposomes encapsulated with (99m)Tc-DTPA showed more uptake in liver, spleen and blood than with positively charged liposomal- and free- (99m)Tc-DTPA. Administration of (232)Th-nitrate to rat significantly increased the levels of liver toxicity markers and of oxidative injury, which were found to be restored more significantly by neutral liposomal-DTPA than free-DTPA. The accumulation of (232)Th in liver and blood of contaminated mice was found to be decreased more significantly by neutral liposomal-DTPA than by free-DTPA. Decorporation and consequent mitigation of (232)Th induced toxicity may be significantly improved by liposomal encapsulation of DTPA, a chelating agent.

  7. Mapping Dust Input to the Global Ocean using Thorium Isotope Measurements in Surface Sediments

    NASA Astrophysics Data System (ADS)

    Kienast, S. S.; Winckler, G.; Lippold, J.; Mahowald, N. M.

    2012-12-01

    Dust input into the ocean-atmosphere system has significant ramifications for biogeochemical cycles and global climate. Thorium-232, sometimes referred to as primordial Thorium, is the longest lived (1.4 1010 yrs) isotope in the U-Th decay chain. It is greatly enriched in upper continental crust compared to oceanic crust and mid-ocean ridge basalt (MORB) like volcanogenic material. In remote areas of the ocean, away from hemipelagic sources of continental material, it is assumed to be of aeolian origin. In conjunction with 230Th-flux normalization, 232Th measurements are thus becoming a promising new proxy for dust accumulation in the present and past ocean. Here, we present a pilot data compilation of previously published 230Th-normalized fluxes of 232Th from a large set of surface sediments originating from the equatorial Pacific, equatorial Atlantic, Southern Ocean, and other areas, complemented by unpublished data. We compare these 232Th fluxes with estimates of present day dust accumulation derived from a coupled atmosphere, land, ocean, and sea-ice model (CCSM-SMOB1). There is excellent agreement between sedimentary and model derived dust fluxes in e.g. the equatorial Atlantic and eastern equatorial Pacific. In the western equatorial Pacific, we observe differences between the sedimentary 232Th record and model estimates. Potential reasons for these discrepancies, and implications for the use of 232Th as dust proxy will be discussed. 1Mahowald et al. . J. Geosphys.Res.111, 2006

  8. Atmospheric thorium pollution and inhalation exposure in the largest rare earth mining and smelting area in China.

    PubMed

    Wang, Lingqing; Zhong, Buqing; Liang, Tao; Xing, Baoshan; Zhu, Yifang

    2016-12-01

    Exposure to radionuclide thorium (Th) has generated widespread public concerns, mainly because of its radiological effects on human health. Activity levels of airborne (232)Th in total suspended particulate (TSP) were measured in the vicinity of the largest rare earth mine in China in August 2012 and March 2013. The mean activity concentrations of (232)Th in TSP ranged from 820μBqm(-3) in a mining area in August 2012 to 39,720μBqm(-3) in a smelting area in March 2013, much higher than the world reference of 0.5μBqm(-3). Multistatistical analysis and Kohonen's self-organizing maps suggested that (232)Th in TSP was mainly derived from rare earth mining and smelting practices. In addition, personal inhalation exposures to (232)Th associated with respirable particulate (PM10) were also measured among local dwellers via personal monitoring. The mean dose values for different age groups in the smelting and mining areas ranged from 97.86 to 417μSvyear(-)(1) and from 101.03 to 430.83μSvyear(-1), respectively. These results indicate that people living in the study areas are exposed to high levels of widespread (232)Th.

  9. Natural radioactivity measurements in the granite rock of quarry sites, Johor, Malaysia

    NASA Astrophysics Data System (ADS)

    Alnour, I. A.; Wagiran, H.; Ibrahim, N.; Laili, Z.; Omar, M.; Hamzah, S.; Idi, Bello. Y.

    2012-12-01

    This study was conducted to determine the concentration of natural radionuclides in the granite rocks of selected quarry sites in Johor state, Malaysia and their possible radiological effects. The activity concentrations of 238U, 232Th and 40K in the areas of study indicated varying values of 238U, 232Th and 40K. The highest values of 238U and 232Th concentrations (67±1 and 85±2 Bq kg-1, respectively) were observed at Kamad Quarry (IJM), whereas the highest value of 40K concentration (722±18 Bq kg-1) was detected in Kim Seng Quarry, while the values of activity concentration are lower in Hanson Quarry Products (Kulai) (25±0.5 for 238U, 24±0.5 for 232Th and 429±11 for 40K). Overall, 40K has the highest concentration in the granite rocks of the quarry sites, followed by 232Th and the least for 238U. The radium equivalent activity concentration was found in the range between 94 and 239 Bq kg-1, the absorbed dose rate was found to be in the range between 47 and 112 nGy h-1, and effective dose ranged from 58 to 137 μSv h-1. Moreover, the internal and external hazard index values were given in results lower than unity.

  10. Quantifying lithogenic inputs to the North Pacific Ocean using the long-lived thorium isotopes

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher T.; Anderson, Robert F.; Fleisher, Martin Q.; Serno, Sascha; Winckler, Gisela; Gersonde, Rainer

    2013-12-01

    Dissolved 232Th is added to the ocean though the partial dissolution of lithogenic materials such as aerosol dust in the same way as other lithogenically sourced and more biologically important trace metals such as Fe. Oceanic 230Th, on the other hand, is sourced primarily from the highly predictable decay of dissolved 234U. The rate at which dissolved 232Th is released by mineral dissolution can be constrained by a Th removal rate derived from 230Th:234U disequilibria, assuming steady-state. Calculated fluxes of dissolved 232Th can in turn be used to estimate fluxes of other lithogenically sourced dissolved metals as well as the original lithogenic supplies, such as aerosol dust deposition, given the concentration and fractional solubility of Th (or other metals) in the lithogenic material. This method is applied to 7 water column profiles from the Innovative North Pacific Experiment (INOPEX) cruise of 2009 and 2 sites from the subtropical North Pacific. The structure of shallow depth profiles suggests rapid scavenging at the surface and at least partial regeneration of dissolved 232Th at 100-200 m depth. This rapid cycling could involve colloidal Th generated during mineral dissolution, which may not be subject to the same removal rates as the more truly dissolved 230Th. An additional deep source of 232Th was revealed in deep waters, most likely dissolution of seafloor sediments, and offers a constraint on dissolved trace element supply due to boundary exchange.

  11. Non-destructive determination of uranium, thorium and 40K in tobacco and their implication on radiation dose levels to the human body.

    PubMed

    Landsberger, S; Lara, R; Landsberger, S G

    2015-11-01

    The naturally occurring radionuclides of (235)U, (238)U and (232)Th and their daughter products are a potential major source of anthropogenic radiation to tobacco smokers. Often overlooked is the presence of (40)K in tobacco and its implication to radiation dose accumulation in the human body. In this study, these three radiation sources have been determined in four typical US cigarettes using neutron activation analysis (NAA). The NAA reactions of (238)U(n,γ)(239)U, (232)Th(n,γ)(233)Th and (41)K(n,γ)(42)K were used to determine (235)U, (238)U and (232)Th and (40)K, respectively. The activity of (238)U can easily be determined by epithermal NAA of the (238)U(n,γ)(239)U reaction, and the activity of (235, 234)U can easily be deduced. Using isotopic ratios, the activity due to (40)K was found by the determined concentrations of (41)K (also by epithermal neutrons) in the bulk material. Each gram of total potassium yields 30 Bq of (40)K. The annual effective dose for smokers using 20 cigarettes per day was calculate to be 14.6, 137 and 9 μSv y(-1) for (238,235,) (234)U, (232)Th and (40)K, respectively. These values are significantly lower that the dose received from (210)Po except for (232)Th.

  12. Uranium-thorium-protactinium dating systematics

    SciTech Connect

    Cheng, H.; Edwards, R.L.; Murrell, M.T.; Benjamin, T.M.

    1998-11-01

    With precise {sup 234}U, {sup 230}Th, and {sup 231}Pa data available, {sup 230}Th and {sup 231}Pa ages can now be tested rigorously for concordancy. If the material is not concordant, the isotope characteristics of this material may be examined in some detail. Here, models similar to those used to describe the U-Pb system are evaluated for use in U-Th-Pa studies, for the case in which initial {sup 230}Th and {sup 231}Pa concentrations are effectively zero. The systematics of concordia plots in relation to models of variation in {delta}{sup 234}U, episodic U or loss or gain, continuous U loss or gain, and continuous {sup 234}U, {sup 230}Th and {sup 231}Pa gain or loss are considered for the case in which initial U concentration is significant (for example, in many carbonate deposits). The authors also examine linear U uptake models for the case in which initial U concentration is effectively zero (for example, in teeth and bones). Such models should prove useful in interpreting data from materials that have behaved as open-systems. In particular, these models may help constrain the nature of diagenetic processes, and in some situations it may be possible to determine or constrain true ages with materials that have behaved as open-systems.

  13. Observation of the negative ions: Ra[sup [minus

    SciTech Connect

    Zhao, X.; Nadeau, M.; Garwan, M.A.; Kilius, L.R.; Litherland, A.E. )

    1993-11-01

    The negative ions of the isotopes [sup 226]Ra, [sup 231]Pa, and [sup 244]Pu have been observed by means of accelerator mass spectrometry and their properties compared with the negative ions of Th and U. The electron affinities of all these elements have been estimated to be similar and greater than 50 meV.

  14. Radionuclide concentration in cabbage samples due to gamma radiation in Samsun, Turkey

    NASA Astrophysics Data System (ADS)

    Altıkulaç, Aydan; Gümüş, Hasan

    2016-11-01

    Establishing of radioactivity planes in foodstuff has emphasis because it allows the evaluation of population exposure to radiation by take nourishment. In this paper, the activity concentrations of 226Ra, 232Th, 40K and 137Cs were determined in cabbage samples collected from Samsun city of Turkey using a gamma ray spectrometry method with a HPGe detector. The mean concentration value of 226Ra, 232Th, 40K and 137Cs in cabbage samples were 1.11±0.03 Bqkg-1, 1.44±0.04 Bqkg-1, 743.75±21.21 Bqkg-1 and 0.18±0.003 Bqkg-1, respectively. The calculated total annual effective dose received from 226Ra, 232Th, 40K and 137Cs due to cabbage samples by population of Samsun province was quite lower than the World average value as suggested by UNSCEAR.

  15. A Lane consistent optical model potential for nucleon scattering on actinide nuclei with extended coupling

    NASA Astrophysics Data System (ADS)

    Quesada, José Manuel; Capote, Roberto; Soukhovitski, Efrem S.; Chiba, Satoshi

    2016-03-01

    An extension for odd-A actinides of a previously derived dispersive coupledchannel optical model potential (OMP) for 238U and 232Th nuclei is presented. It is used to fit simultaneously all the available experimental databases including neutron strength functions for nucleon scattering on 232Th, 233,235,238U and 239Pu nuclei. Quasi-elastic (p,n) scattering data on 232Th and 238U to the isobaric analogue states of the target nucleus are also used to constrain the isovector part of the optical potential. For even-even (odd) actinides almost all low-lying collective levels below 1 MeV (0.5 MeV) of excitation energy are coupled. OMP parameters show a smooth energy dependence and energy independent geometry.

  16. Natural activity concentrations in bottled drinking water and consequent doses.

    PubMed

    Kabadayi, Önder; Gümüs, Hasan

    2012-07-01

    The radioactivity concentrations of nuclides (238)U, (232)Th and (40)K in bottled drinking water from six different manufacturers from Turkey were measured using high-resolution gamma-ray spectrometry. The measurement was done using a coaxial high-purity germanium detector system coupled to Ortec-Dspect jr digital MCA system. The average measured activity concentrations of the nuclides (238)U, (232)Th and (40)K are found to be 0.781, 1.05 and 2.19 Bq l(-1), respectively. The measured activity concentrations have been compared with similar studies from different locations. The annual effective doses for ingestion of radionuclides in the water are found to be 0.0246 mSv for (238)U and 0.169 mSv for (232)Th.

  17. Development of a small scintillation detector with an optical fiber for fast neutrons.

    PubMed

    Yagi, T; Unesaki, H; Misawa, T; Pyeon, C H; Shiroya, S; Matsumoto, T; Harano, H

    2011-02-01

    To investigate the characteristics of a reactor and a neutron generator, a small scintillation detector with an optical fiber with ThO(2) has been developed to measure fast neutrons. However, experimental facilities where (232)Th can be used are limited by regulations, and S/N ratio is low because the background counts of this detector are increase by alpha decay of (232)Th. The purpose of this study is to develop a new optical fiber detector for measuring fast neutrons that does not use nuclear material such as (232)Th. From the measured and calculated results, the new optical fiber detector which uses ZnS(Ag) as a converter material together with a scintillator have the highest detection efficiency among several developed detectors. It is applied for the measurement of reaction rates generated from fast neutrons; furthermore, the absolute detection efficiency of this detector was obtained experimentally.

  18. Correlation of radon and thoron concentrations with natural radioactivity of soil in Zonguldak, Turkey

    NASA Astrophysics Data System (ADS)

    Koray, Abdullah; Akkaya, Gizem; Kahraman, Ayşegül

    2017-02-01

    Radon and thoron gases are produced by the decay of the radioactive elements those are radium and thorium in the soil. In this study, the correlations between soil radon and thoron concentration with their parent nuclide (226Ra and 232Th) concentrations in collected soil samples from the same locations were evaluated. The result of the measurement shows that the distribution of radon and thoron in soil showed the same tendency as 226Ra and 232Th distribution. It was found a weak correlation between the radon and the 226Ra concentration (R =0.57), and between the thoron and the 232Th concentration (R=0.64). No strong correlation was observed between soil-gas radon and thoron concentration (R = 0.29).

  19. Monte Carlo simulation of indoor external exposure due to gamma-emitting radionuclides in building materials

    NASA Astrophysics Data System (ADS)

    Deng, Jun; Cao, Lei; Su, Xu

    2014-10-01

    The use of building materials containing naturally occurring radionuclides, such as 40K, 238U, 232Th and their progeny, could lead to external exposures to the residents of such buildings. In this paper, a set of models are constructed to calculate the specific effective dose rates (the effective dose rate per Bq/kg of 40K, the 238U series, and the 232Th series) imposed on residents by building materials with the MCNPX code. The effect of chemical composition, position concerned in the room and thickness as well as density of material is analyzed. In order to facilitate more precise assessment of indoor external dose due to gamma-emitting radionuclides in building materials, three regressive expressions are proposed and validated by measured data to calculate specific effective rates for 40K. the 238U series and the 232Th series, respectively.

  20. Natural radioactivity and evaluation of effective dose equivalent of granites in Turkey.

    PubMed

    Osmanlioglu, Ahmet Erdal

    2006-01-01

    Annual effective dose equivalent due to natural gamma radiation from (238)U, (232)Th and (40)K have been evaluated from granites in Turkey. Forty samples were taken for spectrometric analysis. Specific concentrations of (238)U, (232)Th and (40)K in granite samples were determined. Spectroscopy system was used with 1.8 keV (FWHM) coaxial high purity germanium (HPGe) detector. Average values of concentrations of (238)U, (232)Th and (40)K were detected at 15.85, 33.76 and 359 Bq kg(-1), respectively. The average value of radon varies from 0.073 to 0.185 Bq m(-2) h(-1) exhalation depends on the specific concentration of uranium. The dose rate due to this highest activity which have been evaluated by a Monte Carlo transport calculations does not exceed 0.4 mSv a(-1).

  1. Estimation of internal radiation dose to the adult Asian population from the dietary intakes of two long-lived radionuclides.

    PubMed

    Iyengar, G V; Kawamura, H; Dang, H S; Parr, R M; Wang, J W; Akhter, Perveen; Cho, S Y; Natera, E; Miah, F K; Nguyen, M S

    2004-01-01

    Daily dietary intakes of two naturally occurring long-lived radionuclides, 232Th and 238U, were estimated for the adult population living in a number of Asian countries, using highly sensitive analytical methods such as instrumental and radiochemical neutron activation analysis (INAA and RNAA), and inductively coupled plasma mass spectrometry (ICP-MS). The Asian countries that participated in the study were Bangladesh (BGD), China (CPR), India (IND), Japan (JPN), Pakistan (PAK), Philippines (PHI), Republic of Korea (ROK) and Vietnam (VIE). Altogether, these countries represent more than 50% of the world population. The median daily intakes of 232Th ranged between 0.6 and 14.4 mBq, the lowest being for Philippines and the highest for Bangladesh, and daily intakes of 238U ranged between 6.7 and 62.5 mBq, lowest and the highest being for India and China, respectively. The Asian median intakes were obtained as 4.2 mBq for 232Th and 12.7 mBq for 238U. Although the Asian intakes were lower than intakes of 12.3 mBq (3.0 ug) 232Th and 23.6 mBq (1.9 ug) 238U proposed by the International Commission on Radiological Protection (ICRP) for the ICRP Reference Man, they were comparable to the global intake values of 4.6 mBq 232Th and 15.6 mBq 238U proposed by the United Nation Scientific Commission on Effects of Radiation (UNSCEAR). The annual committed effective doses to Asian population from the dietary intake of 232Th and 238U were calculated to be 0.34 and 0.20 microSv, respectively, which are three orders of magnitude lower than the global average annual radiation dose of 2400 microSv to man from the natural radiation sources as proposed by UNSCEAR.

  2. Solubility of uranium and thorium from a healing earth in synthetic gut fluids: a case study for use in dose assessments.

    PubMed

    Höllriegl, Vera; Li, Wei Bo; Leopold, Karsten; Gerstmann, Udo; Oeh, Uwe

    2010-11-01

    The aim of this case study was to estimate the bioaccessibility of uranium ((238)U) and thorium ((232)Th) from a healing earth by analysing the solubility of these radionuclides in synthetic gastric and intestinal fluids. An easy applicable in vitro test system was used to investigate the fractional mobilization of the soil contaminants being potentially available for absorption under human in vivo conditions. These findings provided the basis for a prospective dose assessment. The solubility experiments were performed using two different in vitro digestion methods. The concentrations of (238)U and (232)Th in the solutions extracted from the soil were measured by inductively coupled plasma mass spectrometry (ICP-MS). The dissolved fractions in the synthetic gastrointestinal fluid ranged in average from 10.3% to 13.8% for (238)U and from 0.3% to 1.6% for (232)Th, respectively, depending on the digestion method. Subsequently, the committed effective doses from intake of (238)U and (232)Th after ingestion of the healing earth during 1 year were evaluated for adult persons. Thereby ingestion dose coefficients calculated as a function of bioaccessibility were used. The dose assessments ranged between 4.3 × 10(-7)-1.9 × 10(-6) Sv y(-1) for (238)U and 5.6 × 10(-7)-3.3 × 10(-6) Sv y(-1) for (232)Th, respectively. On the basis of the assumptions and estimations made, the present work indicates a relatively low radiation risk due to (238)U and (232)Th after internal exposure of the healing earth.

  3. Measurement of natural and 137Cs radioactivity concentrations at Izmit Bay (Marmara Sea), Turkey

    NASA Astrophysics Data System (ADS)

    Öksüz, I.; Güray, R. T.; Özkan, N.; Yalçin, C.; Ergül, H. A.; Aksan, S.

    2016-03-01

    In order to determine the radioactivity level at Izmit Bay Marmara Sea, marine sediment samples were collected from five different locations. The radioactivity concentrations of naturally occurring 238U, 232Th and 40K isotopes and also that of an artificial isotope 137Cs were measured by using gamma-ray spectroscopy. Preliminary results show that the radioactivity concentrations of 238U and 232Th isotopes are lower than the average worldwide values while the radioactivity concentrations of the 40K are higher than the average worldwide value. A small amount of 137Cs contamination, which might be caused by the Chernobyl accident, was also detected.

  4. Informal progress report on neutron-scattering studies in the actinide region, August 1, 1982-July 31, 1983

    SciTech Connect

    Beghian, L.E.; Kegel, G.H.R.

    1983-01-01

    This informational techical progress report summarizes the principal results of the research performed during the period August 1, 1982 to July 31, 1983. The report covers two areas of neutron cross section measurements: (1) the excited states (E/sub x/ > 650 keV) of /sup 232/Th and /sup 238/U; and (2) the ground state rotational band (0/sup +/, 2/sup +/, 4/sup +/ states) of /sup 232/Th and /sup 238/U from 520 to 940-keV bombarding energy.

  5. Determination of thorium isotopes in mineral and environmental water and soil samples by alpha-spectrometry and the fate of thorium in water.

    PubMed

    Jia, Guogang; Torri, G; Ocone, R; Di Lullo, A; De Angelis, A; Boschetto, R

    2008-10-01

    A method has been developed for determination of thorium isotopes in water and soil samples by alpha-spectrometry. After fusion with Na(2)CO(3) and Na(2)O(2) at 600 degrees C, soil samples were leached with HNO(3) and HCl. Thorium in water sample or in soil leaching solution was coprecipitated together with iron (III) as hydroxides and/or carbonates at pH 9 with ammonia solution, separated from uranium and other alpha-emitters by a Microthene-TOPO (tri-octyl-phosphine oxide) chromatographic column, electrodeposited on a stainless steel disk, and measured by alpha-spectrometry. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained. The detection limits of the method for water (soil) samples are 0.44 microBq l(-1) (0.070 Bq kg(-1)) for (232)Th, 0.80 microBq l(-1) (0.13 Bq kg(-1)) for (230)Th and 1.0 microBq l(-1) (0.16 Bq kg(-1)) for (228)Th, respectively, if 100 l of water (0.50 g) for each sample are analysed. A variety of water or soil samples were analysed using this procedure and giving average thorium yields of 75.5+/-14.2% for water and 93.4+/-4.5% for soil. The obtained concentrations of thorium isotopes in water samples are in the range of 0.0007-0.0326 mBq l(-1) for (232)Th, 232)Th and (228)Th/(232)Th ratios are in the range of 232)Th and (228)Th activity in water is observed and the fate of thorium isotopes in water was studied. The exposure impact due to intake of thorium in the analysed drinking water was evaluated, showing a negligible amount of dose contribution. The concentrations of (232)Th, (230)Th and (228)Th in the analysed soil samples are in the range of 30.2-48.6, 32.5-60.5 and 31.0-53.0 Bq kg(-1), respectively. The obtained mean ratio is 1.04+/-0.05 for (228)Th/(232)Th and 1.20+/-0.41 for (230)Th/(232)Th.

  6. Upwelling Rates Beneath Hotspots : Evidence From U-Series in Basalts From the Mid-Atlantic Ridge and the Azores Islands

    NASA Astrophysics Data System (ADS)

    Bourdon, B. P.; Turner, S. P.

    2001-12-01

    In this study, we have analyzed U-series in lavas from the Azores islands and the nearby Mid-Atlantic Ridge (FAZAR cruise) in an attempt to assess the relative importance of melting processes versus source variations in the context of ridge-hotpsot interaction. The lavas were analyzed for 238U-230Th (Turner et al. 1997, Bourdon et al. 1996) 226Ra-230Th and 235U-231Pa disequilibria by thermal ionisation mass spectrometry. Our results for the historic lavas from the Azores islands show that the 231Pa excess are at the low end of the trend found for other OIB (Pickett et al. 1997 and Bourdon et al. 1998) and fall on a positive correlation in a 231Pa/235U versus 230Th/238U diagram. In contrast, lavas from the nearby Mid-Atlantic ridge are characterized by larger (231Pa/235U) activity ratios for similar and greater (230Th/238U) ratios. There is also a weak correlation between 226Ra/230Th and 231Pa/235U. These data do not indicate a simple mixing trend between an N-MORB and an enriched component in the 231Pa/235U versus 230Th/238U diagram since the MORBs which do not have the most radiogenic isotope signatures compared with the Azores island basalts have some of the largest (230Th/238U) and 231Pa/235U. Clearly, the dynamics of melting must have played a role in generating larger 230Th and 231Pa excesses beneath the Mid-Atlantic ridge. We infer that this must be due to the absence of a lithospheric lid as larger excesses of 230Th and 231Pa can be generated for longer melting columns. Thus, ridge-hotspot interaction cannot imply a simple transfer of melt from the hotspot to the ridge. The 230Th/238U and 226Ra/230Th data across the Azores plateau shows a maximum for the island of Terceira and mimics the depth anomaly which is thought to result from the hotspot. This trend is also consistent with observations of rare gases (M. Moreira pers. comm.) and suggests that it must be related to the presence of deep material. The U-series trend is the reverse of the trend found in

  7. Tracing the metasomatic and magmatic evolution of continental mantle roots with Sr, Nd, Hf and and Pb isotopes: A case study of Middle Atlas (Morocco) peridotite xenoliths

    NASA Astrophysics Data System (ADS)

    Wittig, Nadine; Pearson, D. Graham; Duggen, Svend; Baker, Joel A.; Hoernle, Kaj

    2010-02-01

    We studied clinopyroxenes from spinel-facies peridotite xenoliths sampled by the Quaternary intra-plate volcanism of the Middle Atlas (Morocco) and present new trace element and Sr-Nd-Hf isotope data. However, we focus in particular on Pb isotope data and 238U/ 204Pb and 232Th/ 204Pb ratios of these clinopyroxenes. This data allows us to investigate: (a) the timing of metasomatic events, (b) the prevalence and persistence of elevated 238U/ 204Pb, 232Th/ 238U and 232Th/ 204Pb in continental mantle roots and (c) the 238U/ 204Pb and 232Th/ 204Pb composition of putative basaltic melts generated from such metasomatised sub-continental lithospheric mantle (SCLM). Incompatible trace element concentrations in these clinopyroxenes are elevated, marked by high-field strength element depletion and fractionated elemental ratios (e.g., U/Nb, Zr/Hf) most consistent with enrichment due to carbonatitic liquids. Sr, Nd and Hf isotopes have an affinity to HIMU. U, Th and Pb abundances in the clinopyroxenes generally exceed estimates of primitive mantle clinopyroxene. Pb isotope compositions of these clinopyroxenes are radiogenic and vary between 206Pb/ 204Pb = 19.93-20.25, 207Pb/ 204Pb = 15.63-15.66 and 208Pb/ 204Pb = 39.72-40.23. These Pb isotope systematics result in generally negative Δ7/4 but positive Δ8/4; setting these samples distinctly apart from typical HIMU. These Pb isotope compositions are also distinct from the associated host volcanic rocks. 238U/ 204Pb and 232Th/ 204Pb of these clinopyroxenes, which range from 26 to 81 and 136 to 399, respectively, are elevated and more extreme than estimates of MORB- and HIMU-source mantle. The Pb isotope evolution of the clinopyroxenes suggests that the metasomatic enrichment is younger than 200 Ma, which discounts the volcanic activity due to the opening of the Atlantic and the onset of the collision of the African and Eurasian plates as processes generating the lithophile element and isotope composition of this continental

  8. Radionuclide Transport in Fracture-Granite Interface Zones

    SciTech Connect

    Hu, Q; Mori, A

    2007-09-12

    In situ radionuclide migration experiments, followed by excavation and sample characterization, were conducted in a water-conducting shear zone at the Grimsel Test Site (GTS) in Switzerland to study diffusion paths of radionuclides in fractured granite. In this work, we employed a micro-scale mapping technique that interfaces laser ablation sampling with inductively coupled plasma-mass spectrometry (LA/ICP-MS) to measure the fine-scale (micron-range) distribution of actinides ({sup 234}U, {sup 235}U, and {sup 237}Np) in the fracture-granite interface zones. Long-lived {sup 234}U, {sup 235}U, and {sup 237}Np were detected in flow channels, as well as in the adjacent rock matrix, using the sensitive, feature-based mapping of the LA/ICP-MS technique. The injected sorbing actinides are mainly located within the advective flowing fractures and the immediately adjacent regions. The water-conducting fracture studied in this work is bounded on one side by mylonite and the other by granitic matrix regions. These actinides did not penetrate into the mylonite side as much as the relatively higher-porosity granite matrix, most likely due to the low porosity, hydraulic conductivity, and diffusivity of the fracture wall (a thickness of about 0.4 mm separates the mylonite region from the fracture) and the mylonite region itself. Overall, the maximum penetration depth detected with this technique for the more diffusive {sup 237}Np over the field experimental time scale of about 60 days was about 10 mm in the granitic matrix, illustrating the importance of matrix diffusion in retarding radionuclide transport from the advective fractures. Laboratory tests and numerical modeling of radionuclide diffusion into granitic matrix was conducted to complement and help interpret the field results. Measured apparent diffusivity of multiple tracers in granite provided consistent predictions for radionuclide transport in the fractured granitic rock.

  9. Distribution of Np and Pu in Swedish lichen samples (Cladonia stellaris) contaminated by atmospheric fallout.

    PubMed

    Lindahl, Patric; Roos, Per; Eriksson, Mats; Holm, Elis

    2004-01-01

    The activity concentrations of (237)Np and the two Pu isotopes, (239)Pu and (240)Pu, were determined in lichen samples (Cladonia stellaris) contaminated by fallout from atmospheric nuclear test explosions and the Chernobyl accident. The samples were collected at 18 locations in Sweden, from north to south, between 1986 and 1988 and analysed with high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and alpha spectrometry. Data on the activity ratios (238)Pu/(239+240)Pu and (134)Cs/(137)Cs measured previously were also included in this study for comparison. The (237)Np activity concentration ranged from 0.08 +/- 0.01 to 2.08 +/- 0.17 MBq kg(-1), depending on the location of the sampling site and time of collection. The (239+240)Pu activity concentration ranged from 0.09 +/- 0.01 to 4.09 +/- 0.15 Bq kg(-1), with the (240)Pu/(239)Pu atomic ratio ranging between 0.16 +/- 0.01 and 0.44 +/- 0.03, the higher ratios indicating a combination of weapons test fallout and Chernobyl fallout. The (237)Np/(239)Pu atomic ratios ranged between 0.06 +/- 0.01 and 0.42 +/- 0.04, the lower ratios indicating combination of weapons test fallout and Chernobyl fallout. At a well-defined sampling site at Lake Rogen (62.32 degrees N, 12.38 degrees E), additional lichen samples were collected between 1987 and 1998 to study the distribution of Np and Pu in different layers. The concentrations of the two elements follow each other quite well in the profile.

  10. The influence of citrate and oxalate on (99)Tc(VII), Cs, Np(V) and U(VI) sorption to a Savannah River Site soil.

    PubMed

    Montgomery, D; Barber, K; Edayilam, N; Oqujiuba, K; Young, S; Biotidara, T; Gathers, A; Danjaji, M; Tharayil, N; Martinez, N; Powell, B

    2017-03-25

    Batch sorption experiments were conducted with 0.5-50 ppb (99)Tc, (133)Cs, (237)Np and U in the presence and absence of citrate and/or oxalate in a 25 g/L Savannah River Site (SRS) soil suspension. Citrate and oxalate were the ligands of choice due to their relevancy to plant exudates, the nuclides were selected for their wide range of biogeochemical behavior, and the soil from SRS was selected as a model Department of Energy (DOE) site soil. Batch samples were continually mixed on a rotary shaker and maintained at a pH of approximately 5. Analysis via ICP-MS indicated that sorption of (237)Np increased with ligand concentration compared to baseline studies, as did sorption of (99)Tc although to a lesser extent. The increased sorption of (237)Np is proposed to be due to a combination of factors that are dependent on the ligand(s) present in the specific system including, ligand dissolution of the soil by citrate and formation of tertiary soil-oxalate-Np complexes. The increased (99)Tc sorption is attributed to the dissolution of the soil by the ligands, leading to an increase in the number of available sorption sites for (99)Tc. Uranium sorption decreased and dissolution of native uranium was also observed with increasing ligand concentration, thought to be a result of the formation of strong U-ligand complexes remaining in the aqueous phase. The majority of these effects were observed at the highest ligand concentrations of 50 mgC/L. No notable changes were observed for the (133)Cs system which is ascribed to the minimal interaction of Cs(+) with these organic ligands.

  11. Nuclear waste forms for actinides.

    PubMed

    Ewing, R C

    1999-03-30

    The disposition of actinides, most recently 239Pu from dismantled nuclear weapons, requires effective containment of waste generated by the nuclear fuel cycle. Because actinides (e.g., 239Pu and 237Np) are long-lived, they have a major impact on risk assessments of geologic repositories. Thus, demonstrable, long-term chemical and mechanical durability are essential properties of waste forms for the immobilization of actinides. Mineralogic and geologic studies provide excellent candidate phases for immobilization and a unique database that cannot be duplicated by a purely materials science approach. The "mineralogic approach" is illustrated by a discussion of zircon as a phase for the immobilization of excess weapons plutonium.

  12. INEL advanced test reactor plutonium-238 production feasibility assessment

    SciTech Connect

    Schnitzler, B.G. )

    1993-01-10

    Results of a preliminary neutronics assessment indicate the feasibility of [sup 238]Pu production in the Idaho National Engineering Laboratory Advanced Test Reactor (ATR). Based on the results of this assessment, an annual production of 11.3 kg [sup 238]Pu can be achieved in the ATR. An annual loading of 102 kg [sup 237]Np is required for the particular target configuration and irradiation scenario examined. The [sup 236]Pu contaminant level is approximately 6 parts per million at zero cooling time. The product quality is about 90% [sup 238]Pu. Neptunium feedstock requirements, [sup 238]Pu production rates, or product purity can be optimized depending on their relative importances.

  13. {open_quotes}Transmutation efficiency calculation in the blanket on melted salts with central neptunium target{close_quotes}

    SciTech Connect

    Kolesov, V.F.; Shtarev, S.K.; Khoruzhiy, V.K.

    1995-10-01

    In the limits of ABC project version of two-sectional reactor system in the form of combination of subcritical blanket on melted salts and multiplying target from threshold fissile material {sup 237}Np is considered. This research is the development of the VNIIEF`s earlier work`s (Russia) investigating of usage possibilities in ABC project the conception of multisectional blankets with single-sided neutron coupling between sections. With the help of Monte-Carlo program the calculations results of system mentioned are given. The possibility of accelerator`s considerable power reduction at the account of thorium target substitution with neptunium-237 multiplying target is shown.

  14. In situ subterranean determination of actinides by high-resolution gamma-ray spectrometry

    SciTech Connect

    Brodzinski, R. L.

    1981-04-01

    A system utilizing high resolution germanium diode gamma-ray spectroscopy for the simple, safe, and economical in situ determination of actinides is described. Six isotopes, /sup 235/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, /sup 241/Pu, and /sup 241/Am, can be simultaneously measured at the 10 nCi g/sup -1/ level in less than 7 minutes. Collimators provide for measurement of horizontal strata as thin as 1 cm or solid angles as small as 0.1 steradians. Information obtainable with the system is discussed and compared to that obtainable with neutron activation/detection systems.

  15. Evaluation of New Inorganic Sorbents for Strontium and Actinide Removal from High-Level Nuclear Waste Solutions

    SciTech Connect

    Hobbs, D.T.; Nyman, M.; Medvedev, D.G.; Tripathi, A.; Clearfield, A.

    2004-03-28

    Monosodium titanate (MST), a hydrous metal oxide sorbent, is the baseline material for the removal of 90Sr and alpha-emitting radionuclides (principally 238Pu, 239Pu, 240Pu and 237Np) from alkaline waste solutions generated during the processing of irradiated nuclear materials at the Savannah River Site. This material exhibits excellent performance characteristics for strontium removal. Plutonium removal is also good, but problematic at the estimated bonding concentration. We are currently developing new inorganic materials for improved sorption characteristics. These materials include sodium nonatitanates, pharmacosiderites and heteropolyniobates. We will present results evaluating the performance of these materials with simulated and actual high level nuclear waste solutions.

  16. Alpha self-irradiation effects in ternary oxides of actinides elements: The zircon-like phases Am{sup III}VO{sub 4} and A{sup II}Np{sup IV}(VO{sub 4}){sub 2} (A=Sr, Pb)

    SciTech Connect

    Goubard, F. . E-mail: fabrice.goubard@chim.u-cergy.fr; Griesmar, P.; Tabuteau, A.

    2005-06-15

    We report the experimental studies of irradiation damage from alpha decay in neptunium and americium vanadates versus cumulative dose. The isotopes used were the transuranium {alpha}-emitter {sup 237}Np and the {alpha},{gamma}-emitter {sup 241}Am. Neptunium and americium vanadates self-irradiation was studied by X-ray diffraction method (XRD). The comparison of the powder diffraction patterns reveal that the irradiation has no apparent effect on the neptunium phases while the americium vanadate swells and becomes metamict as a function of cumulative dose.

  17. Sorption of Np (V) by U (VI) hydroxide solids

    SciTech Connect

    Wruck, D A; Brachmann, A; Sylwester, E; Allen, C E A

    1999-09-20

    The distribution of {sup 237}Np(V) between aqueous NaHCO{sub 3} solutions and U(VI) hydroxide solids was investigated. Experiments were initiated by addition of U solids to Np solutions and by coprecipitation of U and Np. Analysis by U L{sub III} extended X-ray absorption fine structure (EXAFS) spectroscopy and infrared absorption spectroscopy indicated the solid phase was synthetic schoepite. Equilibrium Np distribution coefficients were 5-44 mL/g in the pH range 6-8. The results are consistent with adsorption of Np by the solids and provide no evidence of Np incorporation in the bulk solid.

  18. Fission cross section calculations of actinides with EMPIRE code

    SciTech Connect

    Sin, M.; Oblozinsky, P.; Herman,M.; Capote,R.

    2010-04-30

    The cross sections of the neutron induced reactions on {sup 233,234,236}U, {sup 237}Np, {sup 238,242}Pu, {sup 241,243}Am, {sup 242,246}Cm carried out in the energy range 1 keV-20 MeV with EMPIRE code are presented, emphasizing the fission channel. Beside a consistent, accurate set of evaluations, the paper contains arguments supporting the choice of the reaction models and input parameters. A special attention is paid to the fission parameters and their uncertainties.

  19. Alpha self-irradiation effects in ternary oxides of actinides elements: The zircon-like phases Am IIIVO 4 and AIINp IV(VO 4) 2 ( A=Sr, Pb)

    NASA Astrophysics Data System (ADS)

    Goubard, F.; Griesmar, P.; Tabuteau, A.

    2005-06-01

    We report the experimental studies of irradiation damage from alpha decay in neptunium and americium vanadates versus cumulative dose. The isotopes used were the transuranium α-emitter 237Np and the α,γ-emitter 241Am. Neptunium and americium vanadates self-irradiation was studied by X-ray diffraction method (XRD). The comparison of the powder diffraction patterns reveal that the irradiation has no apparent effect on the neptunium phases while the americium vanadate swells and becomes metamict as a function of cumulative dose.

  20. L-edge X-ray absorption studies of neptunium compounds

    NASA Astrophysics Data System (ADS)

    Bertram, S.; Kaindl, G.; Jové, J.; Pagès, M.

    1989-06-01

    The x-ray absorption near-edge structure (XANES) at the Np-L thresholds was investigated for Np compounds with formal valencies III to VII. At LIII, single and double-peaked white lines are observed corresponding to different final states that are populated through core excitation and 5f/ligand hybridization. For the non-metallic Np compounds studied, the weighted mean values of the LIII-XANES shifts relative to NpO2 exhibit a clear correlation with the isomer shifts of the 59-keV Mössbauer resonance of 237Np.

  1. Unusual electric field gradient variation in the NpPd2Ge2 compound

    NASA Astrophysics Data System (ADS)

    Gaczyński, P.; Colineau, E.; Wastin, F.; Boulet, P.; Rebizant, J.; Caciuffo, R.

    2011-01-01

    NpPd2Ge2 has been studied by 237Np Mössbauer spectroscopy between 4.2 K and 80 K. The value of the isomer shift suggests a Np3+ electronic configuration. The low temperature spectra provide a value of 2.10 μB for the magnetic ordered moment on the Np site. These values suggest a rather localized character of the 5f electrons in this system. The magnetic transition around 60 K is accompanied by a large increase of the quadrupolar interaction that is evidence of a redistribution of the electronic charges around the neptunium nucleus.

  2. INEL advanced test reactor plutonium-238 production feasibility assessment

    NASA Astrophysics Data System (ADS)

    Schnitzler, Bruce G.

    1993-01-01

    Results of a preliminary neutronics assessment indicate the feasibility of 238Pu production in the Idaho National Engineering Laboratory Advanced Test Reactor (ATR). Based on the results of this assessment, an annual production of 11.3 kg 238Pu can be achieved in the ATR. An annual loading of 102 kg 237Np is required for the particular target configuration and irradiation scenario examined. The 236Pu contaminant level is approximately 6 parts per million at zero cooling time. The product quality is about 90% 238Pu. Neptunium feedstock requirements, 238Pu production rates, or product purity can be optimized depending on their relative importances.

  3. Mössbauer spectroscopy and neutron diffraction studies of neptunium antimonide NpSb

    NASA Astrophysics Data System (ADS)

    Sanchez, J. P.; Burlet, P.; Quézel, S.; Bonnisseau, D.; Rossat-Mignod, J.; Spirlet, J. C.; Rebizant, J.; Vogt, O.

    1988-09-01

    NpSb has been studied by Mössbauer spectroscopy ( 237Np and 121Sb resonances) and by neutron diffraction using single crystals. Np 3+ magnetic moments order antiferromagnetically below TN = 200 K in a triple- k type I structure. A strong mixing of 5 f electrons with anion p states can be deduced from results of 121Sb resonance. This mixing is certainty at the origin of the interaction mechanism responsible of the coupling between the Fourier components leading to the triple- k multiaxial magnetic structure.

  4. Determination of low level Np-237 by various techniques.

    PubMed

    Benedik, L; Trdin, M

    2017-02-09

    Determination of a low level (237)Np in environmental samples was performed by various techniques: i) a direct gamma-ray spectrometry, ii) an alpha-particle spectrometry that followed pre-separation of neptunium radioisotope(s) by ion-exchange or extraction chromatography and iii) pre-separation radiochemical neutron activation analysis. The methods used were applied to various reference materials with inorganic and organic matrix as well as to a wide range of neptunium content. The results were compared with reference and literature values.

  5. Characteristics of the DINA track dosimeter for monitoring chronic neutron exposure

    SciTech Connect

    Kraitor, S.N.; Kuz'mina, T.D.; Savinskii, A.K.

    1987-09-01

    The DINA personal dosimeter included in the GNEIS beta-, gamma-, and neutron-radiation safety kit uses fission-fragment track detectors and a target containing /sup 237/Np with a /sup 10/B filter. The purpose of this paper is to derive quantitative data on the characteristics of the DINA dosimeter in the measurement of the equivalent kerma during chronic personnel exposure in neutron fields, and to evaluate whether in that situation the dosimeter can be effectively used when only the track dose value varies.

  6. INERT-MATRIX FUEL: ACTINIDE ''BURINGIN'' AND DIRECT DISPOSAL

    SciTech Connect

    Rodney C. Ewing; Lumin Wang

    2002-10-30

    Excess actinides result from the dismantlement of nuclear weapons (Pu) and the reprocessing of commercial spent nuclear fuel (mainly 241 Am, 244 Cm and 237 Np). In Europe, Canada and Japan studies have determined much improved efficiencies for burnup of actinides using inert-matrix fuels. This innovative approach also considers the properties of the inert-matrix fuel as a nuclear waste form for direct disposal after one-cycle of burn-up. Direct disposal can considerably reduce cost, processing requirements, and radiation exposure to workers.

  7. Thorium in the workplace measurement intercomparison.

    PubMed

    Modna, D K; Jerome, S M; White, M A; Woods, M J

    2000-01-01

    The monitoring of radionuclides in the nuclear industry has been recognized as the most straightforward way of assessing health and safety issues associated with the exposure of the workforce to potentially harmful radiation doses. Much of this is achieved by measurements in the workplace itself and by the bioassay and monitoring of workers in the industry. However, there also exists a significant 'non-nuclear' industry where workers are exposed to radioactive materials, for example where this involves thorium, which is made wide use of in the aerospace and other high technology industries. As such work involves the processing of thorium bearing materials, the workforce is potentially exposed to 232Th and its daughter nuclides. Thus, to monitor the workforce effectively, it is important to be able to measure both 232Th and the decay products of 232Th where they are in an unknown state of radioactive equilibrium and this is where monitoring laboratories may experience some difficulty. Accordingly, the Health and Safety Laboratory in the UK has organized a EC wide project on the monitoring of thorium in the 'non-nuclear' workplace; this project is currently ongoing. We report the results of the first intercomparison of this project involving two solutions of 232Th, one in radioactive equilibrium and one not in equilibrium with its daughters. The results are presented with some comments on how this intercomparison has progressed and how these first results will inform the rest of the project.

  8. Measurements of radioactivity in Jamaican building materials and gamma dose equivalents in a prototype red mud house

    SciTech Connect

    Pinnock, W.R. )

    1991-11-01

    Concentrations of 226Ra, 232Th, and 40K measured in bauxite waste, local building materials, and soils are presented and used in model equations to estimate the effective gamma dose-equivalent increments over background in the center of a standard-sized room in a prototype house. Calculated and measured values compare reasonably well.

  9. Natural radioactivity and chemical concentrations in Egyptian groundwater.

    PubMed

    Amin, Rafat M; Khalil, F A; El Fayoumi, M A K

    2011-02-01

    Measurements of natural radioactivity in drinking water have been performed in many parts of the world, mostly for assessment of the doses and risk resulting from consuming water. A study of the radionuclide and chemical components in groundwater from Beni Suef Governate, Egypt has been carried out. Fifty water samples were analyzed by gamma ray spectroscopy to determine the 226Ra, 232Th, and 40K concentrations; major elements, pH, alkalinity, and conductivity were also measured. The specific activity values ranged from 0.008 to 0.040 Bq/l for 226Ra, from 0.003 to 0.019 Bq/l for 232Th, and from 0.025 to 0.344 Bq/l for 40K. The annual ingestions of these radionuclides, using local consumption rates (average over the whole population) of 1.5 l day(-1), were estimated to be 8.59, 4.86, and 83.47 Bq year(-1) for 226Ra, 232Th, and 40K, respectively. The estimated values and weighted means of these radionuclides compare well with the world average. The estimated effective doses from drinking water were found to be 2.4 μSv year(-1) (226Ra), 1.1 μSv year(-1) (232Th), and 0.51 μSv year(-1) (40K). Contribution of these radionuclides to the committed effective dose from 1 year consumption of drinking water is estimated to be only 4%.

  10. Breeding of 233U in the thorium-uranium fuel cycle in VVER reactors using heavy water

    NASA Astrophysics Data System (ADS)

    Marshalkin, V. E.; Povyshev, V. M.

    2015-12-01

    A method is proposed for achieving optimal neutron kinetics and efficient isotope transmutation in the 233U-232Th oxide fuel of water-moderated reactors with variable water composition (D2O, H2O) that ensures breeding of the 233U and 235U isotopes. The method is comparatively simple to implement.

  11. A national survey of natural radionuclides in soils and terrestrial radiation exposure in Iran.

    PubMed

    Kardan, M R; Fathabdi, N; Attarilar, A; Esmaeili-Gheshlaghi, M T; Karimi, M; Najafi, A; Hosseini, S S

    2017-08-24

    In the past, some efforts have been made for measuring natural radioactivity and evaluating public exposure to natural radiation in certain areas of Iran especially in well-known High Level Natural Radiation Areas (HLNRA) in Ramsar and Mahallat. However, the information on radionuclide concentrations, and, consequently, terrestrial radiation exposure for many other areas are not available. There was therefore a need for a systematic and nation-wide survey. For this purpose, 979 soil samples from 31 provinces were collected. The activity concentrations of (40)K, (226)Ra and (232)Th were measured by HPGe detector. The average activity concentrations for Iran were found to be 457.7 Bq/kg for (40)K, 24.3 Bq/kg for (226)Ra and 25.8 Bq/kg for (232)Th. Results were compared with previous regional or provincial surveys. The population-weighted average outdoor and indoor annual effective dose due to external exposure to terrestrial sources of radiation are 0.06 mSv and 0.33 mSv, respectively. It was shown that there is a significant correlation between the activity concentrations of (232)Th and (40)K in soil. In addition, the results of chi square tests show normal and lognormal distributions cannot be considered for the frequency distributions of activity concentration of (232)Th and (226) Ra while (40)K has a normal distribution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. 76 FR 31379 - Notice of Availability of Environmental Assessment and Finding of No Significant Impact for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-31

    ...-232 (Th-232) and radium-226 (Ra-226) are provided in the revised DP. Small quantities of Th-232 and Ra... Soil DCGLs Addendum Soil DCGLs for Thorium and Radium). The revised DP does not change any previously... Radium. August 2010. ABB, Inc. Decommissioning Plan, Revision 2, CE X X ML102310553 X Windsor...

  13. Systematic study of projectile-structure effect on the fusion-barrier distribution

    SciTech Connect

    Roy, Pratap; Saxena, A.; Nayak, B. K.; Mirgule, E. T.; John, B.; Gupta, Y. K.; Danu, L. S.; Vind, R. P.; Choudhury, R. K.; Kumar, Ashok

    2011-07-15

    Quasielastic excitation function measurement has been carried out for the {sup 4}He + {sup 232}Th system at {theta}{sub lab}=160 deg. with respect to the beam direction, to obtain a representation of the fusion-barrier distribution. Using the present data along with previously measured barrier distribution results on {sup 12}C, {sup 16}O, and {sup 19}F + {sup 232}Th systems, a systematic analysis has been carried out to investigate the role of target and/or projectile structures on fusion-barrier distribution. It is observed that for {sup 4}He, {sup 12}C, and {sup 16}O + {sup 232}Th reactions, the couplings due to target states only are required in coupled-channel fusion calculations to explain the experimental data, whereas for the {sup 19}F + {sup 232}Th system along with the coupling of target states, inelastic states of {sup 19}F are also required to explain the experimental results on fusion-barrier distribution. The width of the barrier distribution shows interesting transition behavior when plotted with respect to the target-projectile charge product for the above systems.

  14. Distribution, enrichment and principal component analysis for possible sources of naturally occurring and anthropogenic radionuclides in the agricultural soil of Punjab state, India.

    PubMed

    Kumar, Ajay; Joshi, Vikram M; Mishra, Manish K; Karpe, Rupali; Rout, Sabyasachi; Narayanan, Usha; Tripathi, Raj M; Singh, Jaspal; Kumar, Sanjeev; Hegde, Ashok G; Kushwaha, Hari S

    2012-06-01

    Enrichment factor (EF) of elements including geo-accumulation indices for soil quality and principal component analysis (PCA) were used to identify the contributions of the origin of sources in the studied area. Results of (40)K, (137)Cs, (238)U and (232)Th including their decay series isotopes in the agricultural soil of Mansa and Bathinda districts in the state of Punjab were presented and discussed. The measured mean radioactivity concentrations for (238)U, (232)Th and (40)K in the agricultural soil of the studied area differed from nationwide average crustal abundances by 51, 17 and 43 %, respectively. The sequence of the EFs of radionuclides in soil from the greatest to the least was found to be (238)U > (40)K > (226)Ra > (137)Cs > (232)Th > (228)Ra. Even though the enrichment of naturally occurring radionuclides was found to be higher, they remained to be in I(geo) class of '0', indicating that the soil is uncontaminated with respect to these radionuclides. Among non-metals, N showed the highest EF and belonged to I(geo) class of '2', indicating that soil is moderately contaminated due to intrusion of fertiliser. The resulting data set of elemental contents in soil was also interpreted by PCA, which facilitates identification of the different groups of correlated elements. The levels of the (40)K, (238)U and (232)Th radionuclides showed a significant positive correlation with each other, suggesting a similar origin of their geochemical sources and identical behaviour during transport in the soil system.

  15. Specific activities and radiological hazard assessment in beach sand samples in Songkhla province, Thailand after Fukushima Dai-Ichi nuclear power plant accident in Japan

    NASA Astrophysics Data System (ADS)

    Kessaratikoon, P.; Boonkrongcheep, R.; Choosiri, N.; Daoh, M.; Udomsomporn, S.

    2017-06-01

    According to the Fukushima Dai-Ichi Nuclear Power Plant Accident in Japan on March 11, 2011, specific activities of natural (40K, 226Ra and 232Th) and anthropogenic (137Cs) radionuclides in 210 beach sand samples which were collected from Maharat, Sai Kaew, Samila, Chalatat, Na Thab, Sakom and Soi Sawan beaches in Songkhla Province along the eastern coast of Thailand, have been studied and evaluated. The specific activity levels of 40K, 226Ra, 232Th and 137Cs in the area were found in the range 110.13 - 4574.12, 6.99 - 451.87, 3.75 - 665.76 and 0.58- 9.91 Bq/Kg, respectively. Furthermore, the median values of specific activities of 40K, 226Ra, 232Th and 137Cs were calculated and compared with other research data in Thailand as well as global measurements and evaluations. Moreover, four radiological hazard indices for the studied area were also assessed by using the median values of specific activities of 40K, 226Ra and 232Th.

  16. Half-lives of the actinide nuclei /sup 225/Th,/sup 226/Th,/sup 223/Ac, and /sup 226/Ac

    SciTech Connect

    Miller, G.J.; McGeorge, J.C.; Anthony, I.; Owens, R.O.

    1987-07-01

    Improved values for the half-lives of the nuclei /sup 225,226/Th and /sup 223,226/Ac have been obtained in the course of an experiment on the photodisintegration of /sup 232/Th. The values of several other half-lives in the same mass region were also measured and found to be consistent with previous, but more accurate, determinations.

  17. Gis predictive mapping of terrestrial gamma radiation in the Northern State, Sudan.

    PubMed

    Hamed Bashier, E; Salih, I; Khatir Sam, A

    2012-09-01

    This study presents the evaluation of absorbed dose in air due to gamma-emitting nuclides from (238)U and (232)Th series, (40)K and (137)Cs and the corresponding geographical information system (GIS) predictive mapping for the Northern State. Activity concentration of (238)U, (232)Th , (40)K and (137)Cs in soil samples collected from different locations have been measured using high-resolution gamma spectrometry. On  average, activity concentrations were 19±4 ((238)U), 47±11 ((232)Th), 317±65 ((40)K) and 2.26 Bq kg(-1) for (137)Cs. Absorbed dose rate in air at a height of 1 m above ground surface was calculated using seven sets of dose rate conversion factors (DRCFs) and the corresponding annual effective dose was estimated. On average, the values obtained fall within a narrow range of 44 and 53 nGy h(-1), indicating that the variation in absorbed dose rate is insignificant for different DRCFs. The corresponding annual effective dose ranged from 53 to 65 µSv y(-1). Using GIS, prediction maps for concentrations of (238)U, (232)Th, (40)K and (137)Cs were produced. Also, a map for absorbed dose rate in air at a height of 1 m above the ground level was produced, which showed a trend of increasing from the west towards south-east of the State.

  18. Optical Spectroscopy of an Atomic Nucleus: Progress toward Direct Observation of the 229Th Isomer Transition

    DTIC Science & Technology

    2011-09-28

    3.1. Acquisition of 229Th Thorium is an actinide element , and the most abundant isotope is 232Th with a half life of 1.41010 years [1]. In contrast...isomer u·ansition Sb. GRANT NUMBER Sc. PROGRAM ELEMENT NUMBER 1D10BP 6. AUTHORS Sd. PROJECT NUMBER Wade G . Rellergett, Scott T . Sullivan, David

  19. Transfer Rates of ²³⁸U and ²³²Th for E. globulus, A. mearnsii, H. filipendula and Hazardous Effects of the Usage of Medicinal Plants From Around Gold Mine Dump Environs.

    PubMed

    Tshivhase, Victor M; Njinga, Raymond L; Mathuthu, Manny; Dlamini, Thulani C

    2015-12-10

    Medicinal plant consumption can be a source of human exposure to radioactive elements such as (238)U and (232)Th, which can lead to internal radiation doses. The uptake of (238)U and (232)Th from soils to the leaf samples of three different medicinal plant species (Eucalyptus globulus, Acacia mearnsii and Hyparrhenia filipendula) from the purlieu of the Princess gold mine dump, an abandoned contaminated tailings storage site (TSS), located at longitude 27°55'00″E and latitude 26°09'30″S in Davidsonville (Roodepoort, west of Johannesburg, South Africa) was measured. This was done using ICP-MS spectrometry and substantial differences were observed in the soil-plant transfer factor (TF) values between these radionuclides. The plant species E. globulus exhibited the highest uptake of (238)U, with an average TF of 3.97, while that of H. filipendula was 0.01 and the lowest TF of 0.15 × 10(-2) was measured for A. mearnsii. However, in the case of (232)Th, the highest average TF was observed for A. mearnsii (0.29), followed by E. globulus (0.10) and lowest was measured for H. filipendula (0.27 × 10(-2)). The ratio of TF average value i.e., (238)U to (232)Th in the soil-plant leaves was 38.05 for E. globulus, 0.01 for A. mearnsii and 4.38 for H. filipendula.

  20. Determination of traces of uranium and thorium in titanium and copper used for the construction of the Russian Emission Detector 100 by inductively coupled plasma mass spectrometry.

    PubMed

    Poteshin, Sergey S; Sysoev, Alexey A; Lagunov, Sergey S; Sereda, Andrei; Sosnovtsev, Valery V; Bolozdynya, Alexander I; Efremenko, Yuriy B

    2015-01-01

    The Russian Emission Detector 100 (RED-100) under construction at the National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) is designed to detect the presently undiscovered effect of coherent neutrino scattering. One of the factors limiting the sensitivity of the detector is the spontaneous decay of uranium and thorium in the detector materials. Radioactive impurities in detector materials at levels of parts per billion can significantly affect the sensitivity. Five random samples of titanium and one of copper from materials used in the construction of the detector were selected for assay. The concentration of (232)Th and (238)U were measured by inductively coupled plasma mass spectrometry (ICP- MS) in solid titanium using both: solutions in acids and direct sampling by laser ablation (LA-ICP-MS). The LA- ICP-MS method allowed us to determine (238)U and (232)Th at subnanogram per gram levels. This method is much faster than ICP-MS with liquid injection. The titanium samples studied have impurities in the range between 1 ng g(-1) and 21 ng g(-1) for (238)U and 3 ng g(-1) and 31 ng g(-1) for (232)Th. In copper we set upper limits of 0.4 ng g(-1) for (238)U and 1 ng g(-1)for (232)Th. The total activity of the cryostat constructed from materials studied was estimated to be 43 Bq.

  1. Determination of committed effective doses to skin due to ²³⁸U, ²³²Th and ²²²Rn from the application of various Moroccan black soap (Saboun Beldi) samples by members of the general public.

    PubMed

    Misdaq, M A; Outeqablit, K

    2010-12-01

    (238)U, (232)Th, (222)Rn and (220)Rn concentrations were measured inside various Moroccan black soap samples widely used by the Moroccan population in traditional baths (Hammans) by using both CR-39 and LR-115 type II solid state nuclear track detectors. The measured (238)U, (232)Th, (222)Rn and (220)Rn concentrations, respectively, ranged from (3.7 ± 0.2) to (11.7 ± 0.7) mBq kg(-1), (0.11 ± 0.01) to (0.32 ± 0.02) mBq kg(-1), (3.8 ± 0.2) to (11.6 ± 0.6) Bq kg(-1) and (0.10 ± 0.01) to (0.31 ± 0.02) Bq kg(-1) for the Moroccan black soap samples studied. The influence of pollution on the concentrations of these radionuclides inside the considered Moroccan black soap was investigated. A new dosimetric model for evaluating annual committed effective doses due to (238)U, (232)Th and (222)Rn to the skin of different age groups of the Moroccan populations from the application of the black soap samples studied was developed. The maximum total committed effective dose to the skin due to (238)U, (232)Th and (222)Rn from the application of unpolluted black soap samples 20 min per week by the Moroccan populations was found to be equal to (0.88 ± 0.05) μ Sv y(-1) cm(-2).

  2. Thorium-232 exposure during tungsten inert gas arc welding and electrode sharpening.

    PubMed

    Saito, Hiroyuki; Hisanaga, Naomi; Okada, Yukiko; Hirai, Shoji; Arito, Heihachiro

    2003-07-01

    To assess the exposure of welders to thorium-232 (232Th) during tungsten inert gas arc (TIG) welding, airborne concentrations of 232Th in the breathing zone of the welder and background levels were measured. The radioactive concentrations were 1.11 x 10(-2) Bq/m3 during TIG welding of aluminum (TIG/Al), 1.78 x 10(-4) Bq/m3 during TIG welding of stainless steel (TIG/SS), and 1.93 x 10(-1) Bq/m3 during electrode sharpening, with 5.82 x 10(-5) Bq/m3 background concentration. Although the annual intake of 232Th estimated using these values did not exceed the annual limit intake (ALI, 1.6 x 10(2) Bq), we recommend reducing 232Th exposure by substituting thoriated electrodes with a thorium-free electrodes, setting up local ventilation systems, and by using respiratory protective equipment. It is also necessary to inform workers that thoriated tungsten electrodes contain radioactive material.

  3. Natural thorium isotopes in marine sediment core off Labuan port

    SciTech Connect

    Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R.

    2014-02-12

    Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

  4. Evidence of Dust Deposition in a Core from the Eastern Equatorial Pacific on Glacial-Interglacial Timescales

    NASA Astrophysics Data System (ADS)

    Garwood, J. C.; Kienast, S. S.; Hill, P. S.

    2012-12-01

    Atmospheric dust is recognized to be an important feedback in marine biogeochemical cycles and global climate. This study examines the record of continental input to the eastern equatorial Pacific (EEP), an iron-limited region, over the last 25 kyrs. We measured Thorium-232 (232Th), an isotope greatly enriched in upper continental crust compared to oceanic crust, in core TR163-19P (2.26°N, 90.95°W). We normalized 232Th concentrations to 230Th in order to quantify continental input, and complemented these data with measurements of disaggregated inorganic grain size (DIGS). An end-member mixing analysis of the grain size data was conducted to isolate dust from hemipelagic contributions to the overall inventory of continental material in the core. Our results reveal maximum continental input, dominated by dust, at the last glacial-interglacial transition (~13-16 ka). In addition, we find that overall continental input, based on 232Th fluxes, was higher during the last glacial period than in the Holocene, consistent with earlier findings from the central equatorial Pacific at ~140°W. Dust fluxes derived from grain size distributions, however, exhibit the opposite trend and are elevated in the Holocene compared to the glacial. Our findings emphasize the importance of grain size characterization to complement 232Th fluxes in regions where continental input may have multiple sources. Data will be discussed in the context of other biogeochemical proxies (SST, organic carbon, opal) and regional oceanographic conditions.

  5. Thorium exposure during tungsten inert gas welding with thoriated tungsten electrodes.

    PubMed

    Gäfvert, T; Pagels, J; Holm, E

    2003-01-01

    The exposure to 232Th from TIG welding with thoriated electrodes has been determined at five different workshops. Welding with both alternating and direct current was investigated. The exposure levels of 232Th were generally below 10 mBq m(-3) in the breathing zone of the welders. Two samples from AC welding showed significant higher exposure levels, probably due to maladjustment of the TIG welding power source. Samples of the respirable fraction of 232Th from grinding thoriated electrodes were also collected showing exposure levels of 5 mBq m(-3) or lower. A dose estimate has been made for two scenarios, one realistic and one with conservative assumptions, showing that the annual committed effective dose from inhalation of 232Th, 230Th, 228Th and 228Ra, for a full-time TIG welder, in the realistic case is below 0.3 mSv and with conservative assumptions around 1 mSv or lower. The contribution from grinding electrodes was lower, 10 microSv or lower in the realistic case and 63 microSv or lower based on conservative assumptions. The study does not exclude occurrence of higher exposure levels under welding conditions different from those prevailing in this study.

  6. Breeding of {sup 233}U in the thorium–uranium fuel cycle in VVER reactors using heavy water

    SciTech Connect

    Marshalkin, V. E. Povyshev, V. M.

    2015-12-15

    A method is proposed for achieving optimal neutron kinetics and efficient isotope transmutation in the {sup 233}U–{sup 232}Th oxide fuel of water-moderated reactors with variable water composition (D{sub 2}O, H{sub 2}O) that ensures breeding of the {sup 233}U and {sup 235}U isotopes. The method is comparatively simple to implement.

  7. Redistribution of uranium and thorium series isotopes during isovolumetric weathering of granite

    NASA Astrophysics Data System (ADS)

    Michel, Jacqueline

    1984-06-01

    Previous studies of the distribution of U and Th in parent versus weathered granites have shown both depletion and enrichment of these elements during weathering. In this study, the distribution of U and Th decay series isotopes was determined in a weathering profile of a granitic saprolite, which showed textural preservation indicating isovolumetric weathering. Two types of dissolution methods were used: a whole-rock dissolution and a sodium-citrate dithionite leach to preferentially attack noncrystalline phases of weathering products. Using volume-based activities, 45-70 percent of the total 232Th was gradually removed during weathering. Although the whole-rock 228Th /232Th activity ratios were in equilibrium, there were large excesses of 228Th in the leachable fraction of both parent rock ( 228Th /232Th = 2.06 ) and partially weathered saprolite ( 228Th /232Th = 3-6.5 ), due to alpha recoil and release of daughter 228Th to the weathering rind of the mineral grain. For the most weathered sample, 81 percent of the thorium was in the teachable fraction and 228Th /232Th = 1 , indicating that even the more resistant minerals were attacked. The total U activities showed as much variation in the six parent rock samples as in the weathered profile, and 234U /238U were in equilibrium in both the whole-rock and leachable fractions. 230Th was deficient relative to 234U and 226Ra in both fractions, suggesting recent addition of U and Ra to the entire profile. The large variation in U was not from absorption onto the intermediate weathering products, because only 11-23 percent of the U was in the leachable fraction.

  8. Assessment of gamma radiation exposure of beach sands in highly touristic areas associated with plutonic rocks of the Atticocycladic zone (Greece).

    PubMed

    Papadopoulos, A; Koroneos, A; Christofides, G; Papadopoulou, L; Tzifas, I; Stoulos, S

    2016-10-01

    This study aims to evaluate the activity concentrations of (238)U, (226)Ra, (232)Th, (228)Th and (40)K along beaches close to the plutonic rocks of the Atticocycladic zone that ranged from 15 to 628, 12-2292, 16-10,143, 14-9953 and 191-1192 Bq/kg respectively. A sample from island of Mykonos contained the highest (232)Th content measured in sediments of Greece. The heavy magnetic fraction and the heavy non-magnetic fraction as well as the total heavy fraction, were correlated with the concentrations of the measured radionuclides in the bulk samples. The heavy fractions seem to control the activity concentrations of (238)U and (232)Th of all the samples, showing some local differences in the main (238)U and (232)Th mineral carrier. Similar correlations have been found between (238)U, (232)Th content and rare earth elements concentrations. The measured radionuclides in the beach sands were normalized to the respective values measured in the granitic rocks, which at least in most cases are their most probable parental rocks, so as to provide data upon their enrichment or depletion. Since the Greek beaches are among the most popular worldwide the annual effective dose equivalent received due to sand exposure has been estimated and found to vary between 0.002 and 0.379 mSv y(-1) for tourists and from 0.018 to 3.164 mSv y(-1) for local people working on the beach. The values corresponding to ordinary sand samples are orders of magnitude lower than the limit of 1 mSv y(-1), only in the case of heavy minerals-rich sands the dose could reach or exceed the recommended maximum limit. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Thorium isotopes in colloidal fraction of water from San Marcos Dam, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Cabral-Lares, M.; Melgoza, A.; Montero-Cabrera, M. E.; Renteria-Villalobos, M.

    2013-07-01

    The main interest of this stiidy is to assess the contents and distribution of Th-series isotopes in colloidal fraction of surface water from San Marcos dam, because the suspended particulate matter serves as transport medium for several pollutants. The aim of this work was to assess the distribution of thorium isotopes (232Th and 230Th) contained in suspended matter. Samples were taken from three surface points along the San Marcos dam: water input, midpoint, and near to dam wall. In this last point, a depth sampling was also carried out. Here, three depth points were taken at 0.4, 8 and 15 meters. To evaluate the thorium behavior in surface water, from every water sample the colloidal fraction was separated, between 1 and 0.1 μm. Thorium isotopes concentraron in samples were obtained by alpha spectrometry. Activity concentrations obtained of 232Th and 230Th in surface points ranged from 0.3 to 0.5 Bq ṡ L-1, whereas in depth points ranged from 0.4 to 3.2 Bq ṡ L-1, respectively. The results show that 230Th is in higher concentration than 232Th in colloidal fraction. This can be attributed to a preference of these colloids to adsorb uranium. Thus, the activity ratio 230Th/232Th in colloidal fraction showed values from 2.3 to 10.2. In surface points along the dam, 230Th activity concentration decreases while 232Th concentration remains constant. On the other hand, activity concentrations of both isotopes showed a pointed out enhancement with depth. The results have shown a possible lixiviation of uranium from geological substrate into the surface water and an important fractionation of thorium isotopes, which suggest that thorium is non-homogeneously distributed along San Marcos dam.

  10. Assessment of radionuclide and metal contamination in a thorium rich area in Norway.

    PubMed

    Popic, Jelena Mrdakovic; Salbu, Brit; Strand, Terje; Skipperud, Lindis

    2011-06-01

    The Fen Central Complex in southern Norway, a geologically well investigated area of magmatic carbonatite rocks, is assumed to be among the world largest natural reservoirs of thorium ((232)Th). These rocks, also rich in iron (Fe), niobium (Nb), uranium ((238)U) and rare earth elements (REE), were mined in several past centuries. Waste locations, giving rise to enhanced levels of both radionuclides and metals, are now situated in the area. Estimation of radionuclide and metal contamination of the environment and radiological risk assessment were done in this study. The average outdoor gamma dose rate measured in Fen, 2.71 μGy h(-1), was significantly higher than the world average dose rate of 0.059 μGy h(-1). The annual exposure dose from terrestrial gamma radiation, related to outdoor occupancy, was in the range 0.18-9.82 mSv. The total activity concentrations of (232)Th and (238)U in soil ranged from 69 to 6581 and from 49 to 130 Bq kg(-1), respectively. Enhanced concentrations were also identified for metals, arsenic (As), lead (Pb), chromium (Cr) and zinc (Zn), in the vicinity of former mining sites. Both radionuclide and heavy metal concentrations suggested leaching, mobilization and distribution from rocks into the soil. Correlation analysis indicated different origins for (232)Th and (238)U, but same or similar for (232)Th and metals As, Cr, Zn, nickel (Ni) and cadmium (Cd). The results from in situ size fractionation of water demonstrated radionuclides predominately present as colloids and low molecular mass (LMM) species, being potentially mobile and available for uptake in aquatic organisms of Norsjø Lake. Transfer factors, calculated for different plant species, showed the highest radionuclide accumulation in mosses and lichens. Uptake in trees was, as expected, lower. Relationship analysis of (232)Th and (238)U concentrations in moss and soil samples showed a significant positive linear correlation.

  11. HEU age determination

    SciTech Connect

    Moorthy, A.R.; Kato, W.Y.

    1995-08-01

    A technique has been developed to determine the Highly Enriched Uranium (HEU) Age which is defined as the time since the HEU was produced in an enrichment process. The HEU age is determined from the ratios of relevant uranium parents and their daughters viz {sup 230}Th/{sup 234}U and {sup 231}Pa/{sup 235}U. Uranium isotopes are quantitatively measured by their characteristic gammas and their daughters by alpha spectroscopy. In some of the samples where HEU is enriched more than 99%, the only mode of HEU age determination is by the measurement of {sup 231}Pa since there is negligible quantity of {sup 230}Th due to very low atom concentrations of {sup 234}U in the sample. In this paper we have presented data and methodology of finding the age of two HEU samples.

  12. Impact of the 235U series on doses from intakes of natural uranium and decay progeny.

    PubMed

    Lowe, L M

    1997-10-01

    The doses from 235U series radionuclides have often been ignored in dose assessments involving natural uranium and progeny. This is due to the relatively low abundance of 235U in natural uranium (less than 5% on an activity basis). However, inclusion of the 235U series radionuclides, especially 227Ac and 231Pa, in dose calculations can have a substantial impact on estimated inhalation doses.

  13. U-series disequilibria of trachyandesites from minor volcanic centers in the Central Andes

    NASA Astrophysics Data System (ADS)

    Huang, Fang; Sørensen, Erik V.; Holm, Paul M.; Zhang, Zhao-Feng; Lundstrom, Craig C.

    2017-10-01

    Young trachyandesite lavas from minor volcanic centers in the Central Andes record the magma differentiation processes at the base of the lower continental crust. Here we report U-series disequilibrium data for the historical lavas from the Andagua Valley in Southern Peru to define the time-scale and processes of magmatism from melting in the mantle wedge to differentiation in the crust. The Andagua lavas show (230Th)/(238U), (231Pa)/(235U), and (226Ra)/(230Th) above unity except for one more evolved lava with 230Th depletion likely owing to fractional crystallization of accessory minerals. The 226Ra excess indicates that the time elapsed since magma emplacement and differentiation in the deep crust is within 8000 years. Based on the correlations of U-series disequilibria with SiO2 content and ratios of incompatible elements, we argue that the Andagua lavas were produced by mixing of fresh mantle-derived magma with felsic melt of earlier emplaced basalts in the deep crust. Because of the lack of sediment in the Chile-Peru trench, there is no direct link of recycled slabs with 230Th and 231Pa excesses in the Andagua lavas. Instead, 230Th and 231Pa excesses are better explained by in-growth melting in the upper mantle followed by magma differentiation in the crust. Such processes also produced the 226Ra excess and the positive correlations among (226Ra)/(230Th), Sr/Th, and Ba/Th in the Andagua lavas. The time-scale of mantle wedge melting should be close to the half-life of 231Pa (ca. 33 ka), while it takes less than a few thousand years for magma differentiation to form intermediate volcanic rocks at a convergent margin.

  14. Design study of Thorium-232 and Protactinium-231 based fuel for long life BWR

    NASA Astrophysics Data System (ADS)

    Trianti, N.; Su'ud, Z.; Riyana, E. S.

    2012-06-01

    A preliminary design study for the utilization of thorium added with 231Pa based fuel on BWR type reactor has been performed. In the previous research utilization of fuel based Thorium-232 and Uranium-233 show 10 years operation time with maximum excess-reactivity about 4.075% dk/k. To increase reactor operation time and reduce excess-reactivity below 1% dk/k, Protactinium (Pa-231) is used as Burnable Poison. Protactinium-231 has very interesting neutronic properties, which enable the core to reduce initial excess-reactivity and simultaneously increase production of 233U to 231Pa in burn-up process. Optimizations of the content of 231Pa in the core enables the BWR core to sustain long period of operation time with reasonable burn-up reactivity swing. Based on the optimization of fuel element composition (Th and Pa) in various moderation ratio we can get reactor core with longer operation time, 20 ˜ 30 years operation without fuel shuffling or refuelling, with average power densities maximum of about 35 watt/cc, and maximum excess-reactivity 0.56% dk/k.

  15. Design study of Thorium-232 and Protactinium-231 based fuel for long life BWR

    SciTech Connect

    Trianti, N.; Su'ud, Z.; Riyana, E. S.

    2012-06-06

    A preliminary design study for the utilization of thorium added with {sup 231}Pa based fuel on BWR type reactor has been performed. In the previous research utilization of fuel based Thorium-232 and Uranium-233 show 10 years operation time with maximum excess-reactivity about 4.075% dk/k. To increase reactor operation time and reduce excess-reactivity below 1% dk/k, Protactinium (Pa-231) is used as Burnable Poison. Protactinium-231 has very interesting neutronic properties, which enable the core to reduce initial excess-reactivity and simultaneously increase production of {sup 233}U to {sup 231}Pa in burn-up process. Optimizations of the content of {sup 231}Pa in the core enables the BWR core to sustain long period of operation time with reasonable burn-up reactivity swing. Based on the optimization of fuel element composition (Th and Pa) in various moderation ratio we can get reactor core with longer operation time, 20 {approx} 30 years operation without fuel shuffling or refuelling, with average power densities maximum of about 35 watt/cc, and maximum excess-reactivity 0.56% dk/k.

  16. Creation of a simplified benchmark model for the neptunium sphere experiment

    SciTech Connect

    Mosteller, R. D.; Loaiza, D. J.; Sanchez, R. G.

    2004-01-01

    Although neptunium is produced in significant amounts by nuclear power reactors, its critical mass is not well known. In addition, sizeable uncertainties exist for its cross sections. As an important step toward resolution of these issues, a critical experiment was conducted in 2002 at the Los Alamos Critical Experiments Facility. In the experiment, a 6-kg sphere of {sup 237}Np was surrounded by nested hemispherical shells of highly enriched uranium. The shells were required in order to reach a critical condition. Subsequently, a detailed model of the experiment was developed. This model faithfully reproduces the components of the experiment, but it is geometrically complex. Furthermore, the isotopics analysis upon which that model is based omits nearly 1 % of the mass of the sphere. A simplified benchmark model has been constructed that retains all of the neutronically important aspects of the detailed model and substantially reduces the computer resources required for the calculation. The reactivity impact, of each of the simplifications is quantified, including the effect of the missing mass. A complete set of specifications for the benchmark is included in the full paper. Both the detailed and simplified benchmark models underpredict k{sub eff} by more than 1% {Delta}k. This discrepancy supports the suspicion that better cross sections are needed for {sup 237}Np.

  17. Solvent-extraction purification of neptunium

    SciTech Connect

    Kyser, E.A.; Hudlow, S.L.

    2008-07-01

    The Savannah River Site (SRS) has recovered {sup 237}Np from reactor fuel that is currently being processed into NpO{sub 2} for future production of {sup 238}Pu. Several purification flowsheets have been utilized. An oxidizing solvent-extraction (SX) flowsheet was used to remove Fe, sulfate ion, and Th while simultaneously {sup 237}Np, {sup 238}Pu, u, and nonradioactive Ce(IV) was extracted into the tributyl phosphate (TBP) based organic solvent. A reducing SX flowsheet (second pass) removed the Ce and Pu and recovered both Np and U. The oxidizing flowsheet was necessary for solutions that contained excessive amounts of sulfate ion. Anion exchange was used to perform final purification of Np from Pu, U, and various non-actinide impurities. The Np(IV) in the purified solution was then oxalate-precipitated and calcined to an oxide for shipment to other facilities for storage and future target fabrication. Performance details of the SX purification and process difficulties are discussed. (authors)

  18. Analytical method for the determination of Np and Pu in sea water by AMS with respect to the Fukushima accident

    NASA Astrophysics Data System (ADS)

    Hain, K.; Faestermann, T.; Famulok, N.; Fimiani, L.; Gómez-Guzmán, J. M.; Korschinek, G.; Kortmann, F.; Lierse v. Gostomski, Ch.; Ludwig, P.; Shinonaga, T.

    2015-10-01

    A chemical separation procedure for plutonium (Pu) and neptunium (Np) was developed using extraction chromatography, mass spectrometry and radiometric analysis to determine their concentrations and isotopic ratios in sea water. 241Am, which causes isobaric background to 241Pu in mass spectrometric measurements, was successfully separated from the Pu fraction by this method. Water samples which were spiked with 242Pu and 237Np or 239Np, respectively, were used for chemical yield determination. The chemical yields of Pu and Np, which were determined by alpha and gamma spectrometry at the Radiochemie München (RCM), of more than 85% were obtained. The developed method was applied to analyze the concentration of Pu and Np in the certified reference material, IAEA-443, by Accelerator Mass Spectrometry (AMS) at the Maier-Leibnitz-Laboratory (MLL) to check the applicability of the method to sea water samples. The concentrations of 240Pu, 241Pu and 237Np obtained in this study are in agreement with the certified and literature values within the uncertainties. Due to strong isotopic interference of 239Pu with 238U, it was not possible to analyze the concentration of 239Pu. Some modifications of the chemical separation method to suppress the uranium (U) fraction are under consideration. This method can be used for the analysis of Pu and Np in Pacific Ocean water samples collected after the Fukushima accident.

  19. Calculation of the Reaction Cross Section for Several Actinides

    SciTech Connect

    Hambsch, Franz-Josef; Oberstedt, Stephan; Vladuca, Gheorghita; Tudora, Anabella; Filipescu, Dan

    2005-05-24

    New, self-consistent, neutron-induced reaction cross-section calculations for 235,238U, 237Np, and 231,232,233Pa have been performed. The statistical model code STATIS was extended to take into account the multi-modality of the fission process. The three most dominant fission modes, the two asymmetric standard I (S1) and standard II (S2) modes, and the symmetric superlong (SL) mode have been taken into account. De-convoluted fission cross sections for these modes in 235,238U(n,f) and 237Np(n,f) based on experimental branching ratios, were calculated for the first time up to the second chance fission threshold. For 235U(n,f) and 233Pa(n,f), the calculations being made up to 50 MeV and 20 MeV incident neutron energy, respectively, higher fission chances have been considered. This implied the need for additional calculations for the neighbouring isotopes.As a side product also mass yield distributions could be calculated at energies hitherto not accessible by experiment. Experimental validation of the predictions is being envisaged.

  20. Resonance Region Nuclear Data Analysis to Support Advanced Fuel Cycle Development

    SciTech Connect

    Dunn, Michael E; Derrien, Herve; Leal, Luiz C; Gil, Choong-Sup; Kim, D.

    2011-01-01

    The Oak Ridge National Laboratory (ORNL) and the Korean Atomic Energy Research Institute (KAERI) are performing collaborative research as part of a three-year United States (U.S.) / Republic of Korea (ROK) International Nuclear Energy Research Initiative (I-NERI) project to provide improved neutron cross-section data with uncertainty or covariance data important for advanced fuel cycle and nuclear safeguards applications. ORNL and KAERI have initiated efforts to prepare new cross-section evaluations for 240Pu, 237Np, and the stable Cm isotopes. At the current stage of the I-NERI project, ORNL has recently completed a preliminary resonance-region cross-section evaluation with covariance data for 240Pu and initiated resonance evaluation efforts for 237Np and 244Cm. Likewise, KAERI is performing corresponding high-energy cross-section analyses (i.e., above the resonance region) for the noted isotopes. The paper provides results pertaining to the new resonance region evaluation efforts with emphasis on the new 240Pu evaluation.

  1. Accelerator Mass Spectrometry of Actinides in Ground- and Seawater: An Innovative Method Allowing for the Simultaneous Analysis of U, Np, Pu, Am, and Cm Isotopes below ppq Levels.

    PubMed

    Quinto, Francesca; Golser, Robin; Lagos, Markus; Plaschke, Markus; Schäfer, Thorsten; Steier, Peter; Geckeis, Horst

    2015-06-02

    (236)U, (237)Np, and Pu isotopes and (243)Am were determined in ground- and seawater samples at levels below ppq (fg/g) with a maximum sample size of 250 g. Such high sensitivity was possible by using accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) with extreme selectivity and recently improved efficiency and a significantly simplified separation chemistry. The use of nonisotopic tracers was investigated in order to allow for the determination of (237)Np and (243)Am, for which isotopic tracers either are rarely available or suffer from various isobaric mass interferences. In the present study, actinides were concentrated from the sample matrix via iron hydroxide coprecipitation and measured sequentially without previous chemical separation from each other. The analytical method was validated by the analysis of the Reference Material IAEA 443 and was applied to groundwater samples from the Colloid Formation and Migration (CFM) project at the deep underground rock laboratory of the Grimsel Test Site (GTS) and to natural water samples affected solely by global fallout. While the precision of the presented analytical method is somewhat limited by the use of nonisotopic spikes, the sensitivity allows for the determination of ∼10(5) atoms in a sample. This provides, e.g., the capability to study the long-term release and retention of actinide tracers in field experiments as well as the transport of actinides in a variety of environmental systems by tracing contamination from global fallout.

  2. Sorption kinetics of uranium-238 and neptunium-237 on a glacial sediment

    NASA Astrophysics Data System (ADS)

    Braithwaite, A.; Richardson, S.; Moyes, L. N.; Livens, F. R.; Bunker, D. J.; Hughes, C. R.; Smith, J. T.; Hilton, J.

    2000-02-01

    Studies of uptake of radionuclides by natural materials have shown that sorption may occur via fast equilibrium exchange and/or slow kinetic processes, which can be described using a series of box models. This paper describes the use of such models to evaluate the solid-solution partitioning of 238U and 237Np on a clay rich sediment. Experimental data are obtained using the batch sorption technique, which are then analysed using 1, 2, and 3 box kinetic models. Uptake of 238U is initially rapid, with approximately 90% sorbed within the first 30 minutes. Sorption continues, but at a slower rate. Uptake of 237Np is initially slower than U, with approximately 30% sorbed within the first 30 minutes. Sorption again continues, at a slower rate. Analysis of the experimental data indicates that sorption can be described using 2 and 3 box kinetic models. The results demonstrate that sorption of uranium and neptunium on clay rich sediments occurs via equilibrium and kinetically controlled pathways, with neptunium being controlled by kinetics to a greater extent than uranium. The 2 or 3 box model can describe sorption of neptunium, uranium requires the 3 box model.

  3. Decay Studies of NEPTUNIUM-237.

    NASA Astrophysics Data System (ADS)

    Woods, S. A.

    Available from UMI in association with The British Library. Requires signed TDF. The decay of ^{237}Np (T_{1over2} = 2.14 times 10^6 years) has been investigated from singles and coincidence gamma-ray spectra acquired using Ge detectors and also from internal conversion electron spectra acquired using an iron-free, pi/2 double-focusing, beta-ray spectrometer. Such a long-lived nucleus has a very low specific activity which has previously made the determination of the internal conversion following its decay extremely difficult. In order to overcome this problem, the luminosity of the beta -ray spectrometer has been increased by utilising the multistrip source technique of Bergkvist in conjunction with a sixteen-element proportional counter. Twenty-four gamma-rays have been observed in the singles studies, with four additional gamma -rays observed in the coincidence studies alone, all of which have been placed in the level scheme of ^{233}Pa. The coincidence data also indicates the presence of two unobserved transitions of low energy. The absolute conversion coefficients and multipolarity of five gamma-ray transitions following the decay of ^{237} Np, together with those of seven gamma -ray transitions following the decay of the daughter nucleus, ^{233}Pa, have been determined and the levels of ^{233 }Pa assigned within the framework of the Nilsson Model.

  4. Gastrointestinal absorption of Np in rats

    SciTech Connect

    Wirth, R.; Volf, V.

    1985-11-01

    The effect of Np mass and the acidity of the administered Np solutions as well as the age, sex and nutritional status of the animals injected or gavaged with 239Np or 237Np were determined. The latter factor proved to be dominant for absorption of Np from the gut. Thus in fasting weanling and young adult male rats, the absorption of 239Np was sixfold higher (0.18% and 0.12%, respectively) than in fed ones (0.03% and 0.02%, respectively). Absorption by fasted adult females was 0.05% of the administered 239Np, about half of that of adult males. Raising the Np-mass gavaged to fasted female rats to 1 and 10 mg 237Np/kg resulted in an absorption of 0.23% and 0.26%, respectively. Thus, an increased absorption of Np in adult rats seems to be expected only if a large mass is ingested. No dependence of the absorption of Np on nitric acid concentration was found. The data obtained after oral administration of 238Pu and 239Np to adult rats suggest that the f1 factor recommended by the ICRP for fractional absorption of soluble Np compounds from the gut should be decreased, whereas the f1 factor for soluble Pu compounds should be raised.

  5. Study on retardation mechanism of {sup 3}H, {sup 99}Tc, {sup 137}Np and {sup 241}Am in compacted sodium bentonite

    SciTech Connect

    Sato, H.; Ashida, T.; Kohara, Y.; Yui, M.

    1993-12-31

    The apparent diffusion coefficients were measured at room temperature (about 23{degrees}C) under atmospheric condition by the one-dimensional non-steady state diffusion method for {sup 3}H, {sup 99}Tc, {sup 137}Cs, {sup 237}Np and {sup 241}Am in compacted sodium-bentonite saturated with water. Sodium-bentonite which, is commercially available as KunigelVi{reg_sign}, was used in this study. Experiments were carried out in the density range of 0.4-2.0({times} 10{sup 3}kg/m{sup 3}). Bentonite in the cell was prepared to be saturated with distilled water. The measured apparent diffusion coefficient decreases with increasing dry density of bentonite. That the apparent diffusion coefficient of {sup 3}H decreased as a function of dry density of bentonite appears to be the effect of the change of porous structure with dry density of bentonite. {sup 99}Tc is pertechnetate ion under atmospheric condition. Retardation for {sup 137}Cs may be caused by ion-exchange on bentonite. The sorption, anion-exclusion and molecular filtration are considered as a retardation mechanism for {sup 237}Np and {sup 241}Am because those dominant species are negatively charged and of large ionic size.

  6. Study of the ({sup 3}He,t) Charge Transfer Reaction as a Surrogate for Neutron Energy Between 10 to 20 MeV

    SciTech Connect

    Basunia, M. S.; Clark, R. M.; Bleuel, D. L.; Fallon, P.; Gibelin, J.; McMahan, M. A.; Phair, L.; Rodriguez-Vieitez, E.; Wiedeking, M.; Bernstein, L. A.; Lyles, B. F.; Burke, J. T.; Dietrich, F. S.; Beausang, C. W.; Darakchieva, B.; Evtimova, M.; Lesher, S. R.

    2008-04-17

    We have indirectly determined the {sup 237}Np(n,f) cross section over an equivalent neutron energy range from 10 to 20 MeV using the surrogate reaction {sup 238}U({sup 3}He,tf). A self-supporting {approx}761 {mu}g/cm{sup 2} metallic {sup 238}U foil was bombarded with a 42 MeV {sup 3}He{sup 2+} beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Outgoing charged particles and fission fragments were identified using the Silicon Telescope Array for Reaction Studies (STARS) consisted of two 140 {mu}m and one 1000 {mu}m Micron S2 type silicon detectors. These results were compared with the {sup 237}Np(n,f) cross section data from the direct measurements, the Evaluated Nuclear Data File (ENDF/B-VII.0), and the Japanese Evaluated Nuclear Data Library (JENDL 3.3) and found to closely follow those datasets.

  7. Transmutation of neptunium and americium in a fast neutron flux: EPMA results and KORIGEN predictions for the superfact fuels

    NASA Astrophysics Data System (ADS)

    Walker, C. T.; Nicolaou, G.

    1995-02-01

    In the Superfact Experiment four oxide targets containing high and low concentrations of 237Np and 241Am and representing the homogeneous and heterogeneous in-pile recycling concepts were irradiated in the PHENIX reactor. The burnup reached 6.4% FIMA in the targets with low concentrations of Np and Am and 4.5% FIMA in the targets with high concentrations of Np and Am. About 25% of initial concentration of 237Np and 241Am was transmuted. Generally, the radial distribution of Np and Am was quite flat indicating an even rate of transmutation over the pellet cross section. In the targets with 45% and 20% Np, 10 and 12 wt% Pu was created; most of this was 238Pu with a half-life of 88 y. All the targets exhibited high fission gas release of 67 to 77%. As with standard LMFBR oxide fuel, Cr 2O 3 was the main product of fuel-cladding chemical interaction. In the target containing 20% Am, an FePd alloy was present in all the major radial cracks.

  8. Identifying Sources of Non-fallout Nuclear Contamination in Hudson River Sediments by Plutonium and Neptunium isotope ratios.

    NASA Astrophysics Data System (ADS)

    Kenna, T. C.; Chillrud, S. N.

    2002-12-01

    In an effort to identify and characterize nuclear contaminants released from sources contained within the Hudson River drainage basin, Pu isotopes and 237Np have been measured in a series of sediment cores collected from various locations within the region. During the last several decades, the Hudson River has received input of radioactive contamination from several sources. The first and most significant, has been global fallout, which was a result of atmospheric testing of nuclear weapons primarily by governments of the United States and Former Soviet Union in the 1950s and 1960s. The second, is contamination resulting from reactor releases at the Indian Point Nuclear Power Plant (IPNPP) located on the Hudson River about 35 miles north of New York City. This facility began operation in 1962. A third source of radioactive contamination to the region is contamination resulting from activities at the Knolls Atomic Power Laboratory (KAPL) located on the Mohawk River, which began operation in 1946. Our research entails identifying different sources of nuclear contamination by measurement of plutonium and neptunium isotopic ratios by inductively coupled plasma mass spectrometry (ICP-MS). The isotopic composition of a nuclear contaminant is a sensitive indicator of its origin. By comparing the isotopic composition measured in fluvial sediments to mean values reported for global fallout (i.e. 240Pu/239Pu = 0.18 ñ 0.014, 237Np/239Pu = 0.48 ñ 0.07, and 241Pu/239Pu = .00194 ñ 00028) it is possible to identify contaminants as non-fallout in origin. To date, we have analyzed selected samples from 3 sediment cores collected from the following locations: 1) the Mohawk River downstream of KAPL, 2) the Hudson River above its confluence with the Mohawk River, and 3) the lower Hudson River at a location in close proximity to IPNPP. Isotopic analysis of sediments from the Mohawk River indicates contamination that is clearly non-fallout in origin (240Pu/239Pu ranges between 0

  9. The origin of the 'fluid' component and its implications for U-Th-Pa disequilibria in island arcs

    NASA Astrophysics Data System (ADS)

    Avanzinelli, R.; Skora, S. E.; Blundy, J.; Elliott, T.

    2011-12-01

    Many arc lavas have two discrete slab-derived components evident from their compositional variations. These components have been interpreted to be melts of subducted sediment and a 'fluid' from the mafic oceanic crust. The 'fluid' signature is seen most clearly in depleted samples that contain the smallest fraction of the sediment component. The provenance of this 'fluid' is reliably pinned by its unradiogenic Pb isotope ratios to be from a MORB-like source. The composition of the 'fluid' phase is marked by strong enrichments in the large, divalent cations, notably Ba, Pb and Sr and (238U/230Th)>1. These characteristics have traditionally been explained by the 'mobility' of such elements in an aqueous fluid. Such fluids are anticipated to be generated during prograde, subduction-metamorphism and to flux elements into the mantle wedge. Yet no experimental dataset of solid-aqueous fluid partitioning replicates the full set of elemental enrichments described above. The recent realisation of the pivotal role of accessory phases in controlling the mobility of elements from the slab provides a more consistent explanation of the chemical characteristics of the 'fluid' phase. Notably rutile and allanite retain the 'immobile' HSFE and REE and fractionate Th from U. The enrichments in the 'fluid' thus simply reflect the displacement of homeless elements. However, Ba will not be mobile until its preferred host, phengite, is exhausted at the wet solidus of the mafic crust. Thus the 'fluid' phase transpires to be a wet melt. The dominant control of accessory phases on the composition of the 'fluid' component also helps in understanding the long-standing puzzle of arc lava 235U-231Pa systematics. By analogy with surface aqueous behaviour, many models have assumed that the 'fluid' adds only U to the mantle wedge, generating 238U-230Th and 235U-231Pa excesses. Yet many lavas with strong 'fluid' signatures and large 238U-230Th excesses have 235U-231Pa deficits. This surprising

  10. Beagle: an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans

    SciTech Connect

    Singh, N.P.; Zimmerman, C.J.; Taylor, G.N.; Wrenn, M.E.

    1988-03-01

    The concentrations and the organ distribution patterns of 228Th, 230Th and 232Th in two 9-y-old dogs of our beagle colony were determined. The dogs were exposed only to background environmental levels of Th isotopes through ingestion (food and water) and inhalation as are humans. The organ distribution patterns of the isotopes in the beagles were compared to the organ distribution patterns in humans to determine if it is appropriate to extrapolate the beagle organ burden data to humans. Among soft tissues, only the lungs, lymph nodes, kidney and liver, and skeleton contained measurable amounts of Th isotopes. The organ distribution pattern of Th isotopes in humans and dog are similar, the majority of Th being in the skeleton of both species. The average skeletal concentrations of 228Th in dogs were 30 to 40 times higher than the average skeletal concentrations of the parent 232Th, whereas the concentration of 228Th in human skeleton was only four to five times higher than 232Th. This suggests that dogs have a higher intake of 228Ra through food than humans. There is a similar trend in the accumulations of 232Th, 230Th and 228Th in the lungs of dog and humans. The percentages of 232Th, 230Th and 228Th in human lungs are 26, 9.7 and 4.8, respectively, compared to 4.2, 2.6 and 0.48, respectively, in dog lungs. The larger percentages of Th isotopes in human lungs may be due simply to the longer life span of humans. If the burdens of Th isotopes in human lungs are normalized to an exposure time of 9.2 y (mean age of dogs at the time of sacrifice), the percent burden of 232Th, 230Th and 228Th in human lungs are estimated to be 3.6, 1.3 and 0.66, respectively. These results suggest that the beagle may be an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans.

  11. In-situ gamma-ray survey of rare-earth tailings dams--A case study in Baotou and Bayan Obo Districts, China.

    PubMed

    Li, Baochuan; Wang, Nanping; Wan, Jianhua; Xiong, Shengqing; Liu, Hongtao; Li, Shijun; Zhao, Rong

    2016-01-01

    An in-situ gamma-ray spectrometer survey with a scintillation detector of NaI(Tl) (Φ75 mm × 75 mm) was carried out in the Baotou and Bayan Obo Districts in order to estimate the levels of natural radionuclides near rare-earth (RE) tailings dams. In the RE tailings dam of Baotou, the mean concentrations of (238)U and (232)Th were 3.0 ± 1.0 mg/kg (range: 1.9-4.6 mg/kg) and 321 ± 31 mg/kg (range: 294-355 mg/kg), respectively. In the Bayan Obo tailings dam, the mean concentrations of (238)U and (232)Th were 5.7 ± 0.5 mg/kg (range: 5.3-6.1 mg/kg) and 276 ± 0.5 mg/kg (range: 275.5-276.3 mg/kg), respectively. The average (232)Th concentrations in the mining areas of the Bayan Obo Mine and the living areas of the Bayan Obo Town were 18.7 ± 7.5 and 26.2 ± 9.1 mg/kg, respectively. The (232)Th concentration recorded in the tailings dams was much higher than the global average (7.44 mg/kg). Our investigation shows that the (232)Th concentration in the tailings in the Baotou dam was 34.6 times greater than that in the local soil (in Guyang County); the average concentrations of (232)Th in the soil in the Baotou District and Bayan Obo Districts were about 1.35 and 2.82 times greater, respectively, than that in the soil in Guyang County. Based on our results, the highest estimated effective dose due to gamma irradiation was 1.15 mSv per year, estimated from the data observed in the Baotou tailings dams. The results of this preliminary study indicate the potential importance of radioactivity in RE tailings dams and that remedial measures may be required. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Radiological impacts of phosphogypsum.

    PubMed

    Al Attar, Lina; Al-Oudat, Mohammad; Kanakri, Salwa; Budeir, Youssef; Khalily, Hussam; Al Hamwi, Ahmad

    2011-09-01

    This study was carried out to assess the radiological impact of Syrian phosphogypsum (PG) piles in the compartments of the surrounding ecosystem. Estimating the distribution of naturally occurring radionuclides (i.e. (226)Ra, (238)U, (232)Th, (210)Po and (210)Pb) in the raw materials, product and by-product of the Syrian phosphate fertilizer industry was essential. The data revealed that the concentrations of the radionuclides were enhanced in the treated phosphate ore. In PG, (226)Ra content had a mean activity of 318 Bq kg(-1). The uranium content in PG was low, ca. 33 Bq kg(-1), because uranium remained in the phosphoric acid produced. Over 80% of (232)Th, (210)Po and (210)Pb present partitioned in PG. The presence of PG piles did not increase significantly the concentration of (222)Rn or gamma rays exposure dose in the area studied. The annual effective dose was only 0.082 mSv y(-1). The geometric mean of total suspended air particulates (TSP) ca. 85 μg m(-3). The activity concentration of the radionuclides in filtrates and runoff waters were below the detection limits (ca. 0.15 mBq L(-1) for (238)U, 0.1 mBq L(-1) for (232)Th and 0.18 mBq L(-1) for both of (210)Po and (210)Pb); the concentration of the radionuclides in ground water samples and Qattina Lake were less than the permissible limits set for drinking water by the World Health Organisation, WHO, (10, 1 and 0.1 Bq L(-1) for (238)U, (232)Th and both of (210)Po and (210)Pb, respectively). Eastern sites soil samples of PG piles recorded the highest activity concentrations, i.e. 26, 33, 28, 61 and 40 Bq kg(-1) for (226)Ra, (238)U, (232)Th, (210)Po and (210)Pb, respectively, due to the prevailing western and north-western wind in the area, but remained within the natural levels reported in Syrian soil (13-32 Bq kg(-1) for (226)Ra, 24.9-62.2 Bq kg(-1) for (238)U and 10-32 Bq kg(-1) for (232)Th). The impact of PG piles on plants varied upon the plant species. Higher concentrations of the radionuclides were

  13. Radioactivity levels and radiological hazard indices at the Saudi coastline of the Gulf of Aqaba

    NASA Astrophysics Data System (ADS)

    Al-Trabulsy, H. A.; Khater, A. E. M.; Habbani, F. I.

    2011-03-01

    The coast of the Gulf of Aqaba is subjected to several sources of pollution due to several activities occurring at the coastal area. The activities vary between industrial, tourist and other development aspects at the Jordanian coastline of the Gulf of Aqaba. Phosphate industry has been considered a major source polluting the marine environment. According to official reports, 4-7 million tons of raw phosphate is exported through the Gulf of Aqaba. During transportation and loading, a small proportion of this enters the waters of the Gulf. Phosphate dust has also been considered another source of nutrients loading to the Gulf. 19 sediment samples were collected along the Saudi Gulf coastline, from the Saudi-Jordan border down to the end of the Gulf at Tiran Strait. Measurements of the activity concentrations of 226Ra, 232Th, 40K and 137Cs in Bq/kg (in dry weight) of the collected samples were carried out using gamma-ray spectrometry based on a highly pure germanium coaxial detector (HPGe). The concentrations of 238U and 232Th were also determined using ICP-MS technique. The average specific activities for 226Ra, 232Th, 40K and 137Cs were found to be 11.4±1.5, 22.5±3.7, 641.1±61.3 and 3.5±0.7 Bq/kg, respectively. The results show that the mean activity of 226Ra and 232Th is lower than the world average of 25 Bq/kg for both of them, whereas the mean value for 40K is about double the world average of 370 Bq/kg. The presence of 137Cs in the analyzed samples is low in most locations. The mean concentrations of 238U and 232Th in the study area are 1.2 and 5.4 mg/kg, respectively, and the ratio 238U/ 232Th is 0.2, which is lower than the global ratio of 0.3. The ratio of 226Ra/ 228Ra was found to decrease southwards in the direction of Tiran Strait, away from the phosphate industry in Jordan. Mean values for radium equivalent, absorbed dose, annual effective dose, external and internal hazard index and representative level index were determined as: 92.9 Bq/kg, 45.6 n

  14. Initial 230Th and isotopic compositions of U and Th in a Holocene stalagmite from Ninh Binh, Vietnam

    NASA Astrophysics Data System (ADS)

    Shen, C.; Sung, Y.; Chen, Y.; Ho, W.; Wang, X.; Galang, C.; Cheng, H.; Edwards, R.; Burr, G.; Lam, D.

    2003-12-01

    The application of the 238U-234U-230Th disequilibrium dating technique to cave carbonates has provided access to a valuable source of Quaternary environmental information. For some speleothems, however, the initial Th associated with the incorporation of detrital materials into the growing carbonate matrix can bias the true ages, which play a pivotal role in the paleo-sciences. Isochron techniques and development diagrams (Cheng et al., 2000, {\\ G.C.A.}, 64, 2401-2416) were used on a stalagmite with unusually high thorium concentrations of 5-130 ppm and low uranium concentration of 100-300 ppb, collected from Ninh Binh, Vietnam, in order to evaluate the initial 230Th values, 230Th/232Th ratios and ages. Uranium and thorium concentrations and isotopic compositions for forty subsamples collected from eight horizons of this 4600-yr old speleothem were analyzed by ICP-MS techniques (Shen et al., 2002, {\\ Chem. Geology}, 185, 165-178). Results from the application of isochron techniques were: (1) 50-90% of the 230Th was deposited initially and must be subtracted from measured 230Th in order to obtain accurate ages; (2) in some cases, discordant ages were obtained among subsamples on the same horizon if the same initial of 230Th/232Th was used for correction; (3) there was some variability in the initial 230Th/232Th values for different layers. These observations indicate that there are many Th sources with different concentrations and 230Th/232Th ratios introduced into growing layers during crystallization. Accordingly, the initial values of 230Th/232Th ratios vary between and within horizons. Such heterogeneous coprecipitation of detrital materials places some limits on the utility of simple two-dimensional isochron approaches to speleothems with large and complicated Th contamination, which enhances the uncertainty of estimated ages. If the development diagram technique is also employed, the initial values of 230Th/232Th ratios are more tightly constrained, varying

  15. Experiments on parity violation in the compound nucleus

    SciTech Connect

    Bowman, J.D.

    1996-09-01

    Results from experiments that measure parity-violating longitudinal asymmetries in the scattering of epithermal neutrons from compound-nuclear resonances at the Manuel Lujan Neutron Scattering Center at Los Alamos are discussed. Parity non-conserving asymmetries have been observed for many p-wave resonances in a single target. Measurements were performed on several nuclei in the mass region of A-100 and A-230. The statistical model of the compound nucleus provides a theoretical basis for extracting mean-squared matrix elements from the experimental asymmetry data, and for interpreting the mean-squared matrix elements. The constraints on the weak meson-exchange couplings calculated from the compound-nucleus asymmetry data agree qualitatively with the results from few-body and light-nuclei experiments. For all nuclei but {sup 232}Th measured asymmetries have random signs. For {sup 232}Th eight of eight measured asymmetries are positive. This phenomenon is discussed in terms or doorway models.

  16. Mussels (Mytilus galloprovincialis) as a bio-indicator species in radioactivity monitoring of Eastern Adriatic coastal waters.

    PubMed

    Krmpotić, Matea; Rožmarić, Martina; Barišić, Delko

    2015-06-01

    Croatian Adriatic coastal waters are systematically monitored within the Mediterranean Mussel Watch Project using mussels (Mytilus galloprovincialis) as a bio-indicator species. The study includes determination of naturally occurring ((7)Be, (40)K, (232)Th, (226)Ra and (238)U), as well as anthropogenic (137)Cs radionuclides. Activity concentrations in dry weight of mussels' soft tissue along the Croatian Adriatic coast are presented, with spatial and seasonal variations given and discussed. Samples were collected in spring and autumn for the period between 2009 and 2013. Radionuclides were determined by gamma-ray spectrometry. Activity concentrations of (7)Be were the highest in spring periods, especially in the areas with significant fresh water discharges. Activity concentrations of (40)K did not vary significantly with season or location. (137)Cs activities were low, while (232)Th, (226)Ra and (238)U activities were mostly below the detection limit of performed gamma-spectrometric measurement.

  17. Distribution of uranium and thorium in groundwater of arid climate region

    NASA Astrophysics Data System (ADS)

    Murad, Ahmed; Alshamsi, Dalal; Aldahan, Ala; Hou, Xiaolin

    2014-05-01

    Uranium, thorium and their decay products are the most common radionuclides in groundwater in addition to potassium-40. Once groundwater is used for drinking, domestic and irrigation purposes, the radionuclides will then pose environmental and health related hazard originating from radioactivity and toxicity. In the investigation presented here, assessment of 238U, 235U and 232Th concentrations in groundwater across of the United Arab Emirates (UAE) is evaluated in terms of quality and sources. The region is dominated by arid climate conditions and radioactivity assessment of groundwater is essential for safe use of groundwater. Furthermore, the results were linked to data from other arid regions and worldwide. Groundwater samples (total dissolved solids,TDS, 142.5 mg L-1 to 12770 mg L-1) from 67 different wells were collected across geomorphologically different areas and most of the wells are actively used for agriculture. The aquifers are recent sand dunes, Quaternary (3 million years to present) sediments, and older carbonate rocks (230-10 million years). The 235U, 238U and 232Th measurements were carried out using ICP-MS system equipped with an Xt-skimmer cone and a concentric nebulizer under hot plasma conditions. Concentrations of 235U, 238U and 232Th range at (0.125-508.4) ng L-1, (25.81-69237) ng L-1 and (0.236-2529) ng L-1, respectively. Apparently, most 235U, 238U, 232Th concentrations in the sampled groundwater are below the WHO proposed permissible level of 60000 ng/L for total uranium (1 Bq L-1 for 235U and 10 Bq L-1 for 238U) and 5000 ng L-1 (1Bq L-1) for 232Th. A few samples show high concentrations of uranium that are associated with high TDS values and occur within interbedded limestones and shales aquifer. Comparison with worldwide groundwater data suggests that 238U concentration is highest in the arid regions groundwater where the recharge to aquifers is relatively low. The situation for 232Th concentrations seems less affected by climatic

  18. Radiological Impact of Phosphogypsum Application in Agriculture

    NASA Astrophysics Data System (ADS)

    Dias, Nivea M. P.; Caires, Eduardo F.; Pires, Luiz F.; Bacchi, Marcio A.; Fernandes, Elisabete A. N.

    2010-08-01

    Phosphogypsum (PG) contains radionuclides from 238U and 232Th decay series. Due to the presence of these radionuclides, many countries restricted the use of PG in agriculture, however there is not such restriction in Brazil. The main objective of this work was to evaluate the impact of PG application on 226Ra (238U) and 228Ra (232Th) concentrations in soil. Gamma-spectrometry was carried out using HPGe detector. No increment of 226Ra and 228Ra was observed for increasing PG doses. Average values found for 226Ra and 228Ra were respectively 37 Bq kg-1 and 57 Bq kg-1. The results showed that the increasing PG doses in the specific conditions of the experiment did not cause a significant increment of radionuclides.

  19. Radiological Impact of Phosphogypsum Application in Agriculture

    SciTech Connect

    Dias, Nivea M. P.; Caires, Eduardo F.; Pires, Luiz F.; Bacchi, Marcio A.; Fernandes, Elisabete A. N.

    2010-08-04

    Phosphogypsum (PG) contains radionuclides from {sup 238}U and {sup 232}Th decay series. Due to the presence of these radionuclides, many countries restricted the use of PG in agriculture, however there is not such restriction in Brazil. The main objective of this work was to evaluate the impact of PG application on {sup 226}Ra ({sup 238}U) and {sup 228}Ra ({sup 232}Th) concentrations in soil. Gamma-spectrometry was carried out using HPGe detector. No increment of {sup 226}Ra and {sup 228}Ra was observed for increasing PG doses. Average values found for {sup 226}Ra and {sup 228}Ra were respectively 37 Bq kg{sup -1} and 57 Bq kg{sup -1}. The results showed that the increasing PG doses in the specific conditions of the experiment did not cause a significant increment of radionuclides.

  20. 238U-230Th-226Ra disequilibria in dacite and plagioclase from the 2004-2005 eruption of Mount St. Helens: Chapter 36 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Cooper, Kari M.; Donnelly, Carrie T.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    230Th)/(232Th) measured for the 1980s reference suite. However, (230Th)/(232Th) for plagioclase separates for dome samples erupted during October and November 2004 are significantly different from corresponding whole-rock values, which suggests that a large fraction (>30 percent) of crystals in each sample are foreign to the host liquid. Furthermore, plagioclase in the two 2004 samples have U-series characteristics distinct from each other and from plagioclase in dacite erupted in 1982, indicating that (1) the current eruption must include a component of crystals (and potentially associated magma) that were not sampled by the 1980-86 eruption, and (2) dacite magmas erupted only a month apart in 2004 contain different populations of crystals, indicating that this foreign component is highly heterogeneous within the 2004-5 magma reservoir.

  1. Limits on uranium and thorium bulk content in GERDA Phase I detectors

    NASA Astrophysics Data System (ADS)

    GERDA Collaboration; Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakemüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2017-05-01

    Internal contaminations of 238U, 235U and 232Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of 76Ge. The data from GERDA Phase I have been analyzed for alpha events from the decay chain of these contaminations by looking for full decay chains and for time correlations between successive decays in the same detector. No candidate events for a full chain have been found. Upper limits on the activities in the range of a few nBq/kg for 226Ra, 227Ac and 228Th, the long-lived daughter nuclides of 238U, 235U and 232Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from 226Ra and 228Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment.

  2. Assessment of radiation hazards due to natural radioactivity in some building materials used in Egyptian dwellings.

    PubMed

    Medhat, M E

    2009-02-01

    Different types of Egyptian building materials from various locations in Cairo and its suburbs have been analysed for natural radioactivity using gamma ray spectrometry. Concentrations of (226)Ra, (232)Th and (40)K were in the ranges of (12 +/- 2.8-65 +/- 6.5), (5 +/- 1.8-60 +/- 6.7) and (159 +/- 3.8-920 +/- 12.7 Bq kg(-1)), respectively. The minimum concentration of (226)Ra, (232)Th and (40)K was found in gravel samples, whereas the maximum in granite samples. The results are compared with the published data of other countries and with the world average limits. The radiological hazard parameters: radium equivalent activity, gamma index, alpha index, absorbed dose rate and the annual exposure rate, were determined to assess the radiation hazards associated with Egyptian buildings. All studied samples are lower than world average limits.

  3. Natural radioactivity in Algerian building materials.

    PubMed

    Amrani, D; Tahtat, M

    2001-04-01

    Samples of natural and manufactured building materials collected from Algiers have been analysed for 226Ra, 232Th and 40K using a high-resolution HPGe gamma-spectrometry system. The specific concentrations for 226Ra, 232Th and 40K, from the selected building materials, ranged from (12-65 Bq kg(-1)), (7-51 B qkg(-1)) and (36-675 Bq kg(-1)), respectively. The measured activity concentrations for these natural radionuclides were compared with the reported data of other countries and with the world average activity of soil. Radium-equivalent activities were calculated for the measured samples to assess the radiation hazards arising from using those materials in the construction of dwellings. All building materials showed Ra(eq) activities lower than the limit set in the OECD report (370 Bq kg(-1)), equivalent to external gamma-dose of 1.5 mSv yr(-1).

  4. Natural radioactivity concentration of peanuts in Osmaniye-Turkey

    SciTech Connect

    Akkurt, Iskender; Guenoglu, Kadir; Mavi, Betuel; Kara, Ayhan

    2012-09-06

    The peanut is grown in Osmaniye where located in southern Turkey. Due to it is grown underground, the measurements of natural radioactivity of peanuts become important. For this reason some peanut samples have been collected from different places of Osmaniye and the measurements of natural activity concentrations for {sup 40}K, {sup 226}Ra and {sup 232}Th in some peanuts samples have been carried out using a NaI(Tl) gamma-ray spectrometer. Activity of {sup 40}K was measured from its intensive line at 1460 keV, for {sup 226}Ra activity peak from {sup 214}Bi at 1760 keV and {sup 232}Th activity, peak from {sup 208}Tl at energy of 2610 keV was used.

  5. Electric dipole moments in {sup 230,232}U and implications for tetrahedral shapes

    SciTech Connect

    Ntshangase, S. S.; Bark, R. A.; Datta, P.; Lawrie, E. A.; Lawrie, J. J.; Lieder, R. M.; Mullins, S. M.; Aschman, D. G.; Mohammed, H.; Stankiewicz, M. A.; Bvumbi, S.; Masiteng, P. L.; Shirinda, O.; Davidson, P. M.; Nieminen, P.; Wilson, A. N.; Dinoko, T. S.; Sharpey-Shafer, J. F.; Elbasher, M. E. A.; Juhasz, K.

    2010-10-15

    The nuclei {sup 230}U and {sup 232}U were populated in the compound nucleus reactions {sup 232}Th({alpha},6n) and {sup 232}Th({alpha},4n), respectively. Gamma rays from these nuclei were observed in coincidence with a recoil detector. A comprehensive set of in-band E2 transitions were observed in the lowest lying negative-parity band of {sup 232}U while one E2 transition was also observed for {sup 230}U. These allowed B(E1;I{sup -{yields}}I{sup +}-1)/B(E2;I{sup -{yields}}I{sup -}-2) ratios to be extracted and compared with systematics. The values are similar to those of their Th and Ra isotones. The possibility of a tetrahedral shape for the negative-parity U bands appears difficult to reconcile with the measured Q{sub 2} values for the isotone {sup 226}Ra.

  6. Assessment of indoor absorbed gamma dose rate from natural radionuclides in concrete by the method of build-up factors.

    PubMed

    Manić, Vesna; Nikezic, Dragoslav; Krstic, Dragana; Manić, Goran

    2014-12-01

    The specific absorbed gamma dose rates, originating from natural radionuclides in concrete, were calculated at different positions of a detection point inside the standard room, as well as inside an example room. The specific absorbed dose rates corresponding to a wall with arbitrary dimensions and thickness were also evaluated, and appropriate fitting functions were developed, enabling dose rate calculation for most realistic rooms. In order to make calculation simpler, the expressions fitting the exposure build-up factors for whole (238)U and (232)Th radionuclide series and (40)K were derived in this work, as well as the specific absorbed dose rates from a point source in concrete. Calculated values of the specific absorbed dose rates at the centre point of the standard room for (238)U, (232)Th and (40)K are in the ranges of previously obtained data. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Determination of thorium by ICP-MS and ICP-OES.

    PubMed

    Holmes, L

    2001-01-01

    Natural thorium (232-Th) has traditionally been measured by radiometric techniques such as alpha and gamma spectrometry. However. with both ICP-OES and ICP-MS instruments becoming relatively common in many analytical laboratories. these techniques have become more acceptable in thorium analysis. This paper will briefly describe an overview of the instrumentation currently available and the techniques themselves applied to thorium analysis. Both techniques have low detection limits and require little sample treatment after the sample digestion. Routine sample analysis time is short and spectra easy to interpret. usually giving results with low uncertainties, Whereas ICP-OES measures total thorium only, ICP-MS also offers the potential to measure other long-lived thorium isotopes (t 1/2 > 10(4) years), such as 232Th. However, other important isotopes, such as 228Th. are still out of reach for routine analysis. The main disadvantage of the techniques is the requirement for a sample digestion stage.

  8. Measurement of the total activity concentrations of Libyan oil scale

    NASA Astrophysics Data System (ADS)

    Da Silva, F. C. A.; Bradley, D. A.; Regan, P. H.; Rozaila, Z. Siti

    2017-08-01

    Twenty-three oil scale samples obtained from the Libyan oil and gas industry production facilities onshore have been measured using high-resolution gamma-ray spectrometry with a shielded HPGe detector, the work being carried out within the Environmental Radioactivity Laboratory at the University of Surrey. The main objectives of this work were to determine the extent to which the predominant radionuclides associated with the uranium and thorium natural decay chains were in secular equilibrium with their decay progeny, also to compare differences between the total activity concentrations (TAC) in secular equilibrium and disequilibrium and to evaluate the measured activities for the predominant gamma-ray emitting decay radionuclides within the 232Th and 238U chains. The oil scale NORM samples did not exhibit radioactive equilibrium between the decay progeny and longer-lived parent radionuclides of the 238U and 232Th series.

  9. Resonance Region Covariance Analysis Method and New Covariance Data for Th-232, U-233, U-235, U-238, and Pu-239

    SciTech Connect

    Leal, Luiz C; Arbanas, Goran; Derrien, Herve; Wiarda, Dorothea

    2008-01-01

    Resonance-parameter covariance matrix (RPCM) evaluations in the resolved resonance region were done for 232Th, 233U, 235U, 238U, and 239Pu using the computer code SAMMY. The retroactive approach of the code SAMMY was used to generate the RPCMs for 233U, 235U. RPCMs for 232Th, 238U and 239Pu were generated together with the resonance parameter evaluations. The RPCMs were then converted in the ENDF format using the FILE32 representation. Alternatively, for computer storage reasons, the FILE32 was converted in the FILE33 cross section covariance matrix (CSCM). Both representations were processed using the computer code PUFF-IV. This paper describes the procedures used to generate the RPCM with SAMMY.

  10. Measurement of natural and {sup 137}Cs radioactivity concentrations at Izmit Bay (Marmara Sea), Turkey

    SciTech Connect

    Öksüz, İ. Güray, R. T. Özkan, N. Yalçin, C.; Ergül, H. A. Aksan, S.

    2016-03-25

    In order to determine the radioactivity level at Izmit Bay Marmara Sea, marine sediment samples were collected from five different locations. The radioactivity concentrations of naturally occurring {sup 238}U, {sup 232}Th and {sup 40}K isotopes and also that of an artificial isotope {sup 137}Cs were measured by using gamma-ray spectroscopy. Preliminary results show that the radioactivity concentrations of {sup 238}U and {sup 232}Th isotopes are lower than the average worldwide values while the radioactivity concentrations of the {sup 40}K are higher than the average worldwide value. A small amount of {sup 137}Cs contamination, which might be caused by the Chernobyl accident, was also detected.

  11. Certified reference materials for radionuclides in Bikini Atoll sediment (IAEA-410) and Pacific Ocean sediment (IAEA-412).

    PubMed

    Pham, M K; van Beek, P; Carvalho, F P; Chamizo, E; Degering, D; Engeler, C; Gascó, C; Gurriaran, R; Hanley, O; Harms, A V; Herrmann, J; Hult, M; Ikeuchi, Y; Ilchmann, C; Kanisch, G; Kis-Benedek, G; Kloster, M; Laubenstein, M; Llaurado, M; Mas, J L; Nakano, M; Nielsen, S P; Osvath, I; Povinec, P P; Rieth, U; Schikowski, J; Smedley, P A; Suplinska, M; Sýkora, I; Tarjan, S; Varga, B; Vasileva, E; Zalewska, T; Zhou, W

    2016-03-01

    The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certified radionuclides include: (40)K, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (232)Th, (234)U, (238)U, (239)Pu, (239+240)Pu and (241)Am for IAEA-410 and (40)K, (137)Cs, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (232)Th, (235)U, (238)U, (239)Pu, (240)Pu and (239+240)Pu for IAEA-412. The CRMs can be used for quality assurance and quality control purposes in the analysis of radionuclides in sediments, for development and validation of analytical methods and for staff training.

  12. Environmental consequences of uranium atmospheric releases from fuel cycle facility: II. The atmospheric deposition of uranium and thorium on plants.

    PubMed

    Pourcelot, L; Masson, O; Renaud, P; Cagnat, X; Boulet, B; Cariou, N; De Vismes-Ott, A

    2015-03-01

    Uranium and thorium isotopes were measured in cypress leaves, wheat grains and lettuce taken in the surroundings of the uranium conversion facility of Malvési (South of France). The comparison of activity levels and activity ratios (namely (238)U/(232)Th and (230)Th/(232)Th) in plants with those in aerosols taken at this site and plants taken far from it shows that aerosols emitted by the nuclear site (uranium releases in the atmosphere by stacks and (230)Th-rich particles emitted from artificial ponds collecting radioactive waste mud) accounts for the high activities recorded in the plant samples close to the site. The atmospheric deposition process onto the plants appears to be the dominant process in plant contamination. Dry deposition velocities of airborne uranium and thorium were measured as 4.6 × 10(-3) and 5.0 × 10(-3) m s(-1), respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Study of secondary neutron interactions with ²³²Th, ¹²⁹I, and ¹²⁷I nuclei with the uranium assembly "QUINTA" at 2, 4, and 8 GeV deuteron beams of the JINR Nuclotron accelerator.

    PubMed

    Adam, J; Chilap, V V; Furman, V I; Kadykov, M G; Khushvaktov, J; Pronskikh, V S; Solnyshkin, A A; Stegailov, V I; Suchopar, M; Tsoupko-Sitnikov, V M; Tyutyunnikov, S I; Vrzalova, J; Wagner, V; Zavorka, L

    2016-01-01

    The natural uranium assembly, "QUINTA", was irradiated with 2, 4, and 8GeV deuterons. The (232)Th, (127)I, and (129)I samples have been exposed to secondary neutrons produced in the assembly at a 20-cm radial distance from the deuteron beam axis. The spectra of gamma rays emitted by the activated (232)Th, (127)I, and (129)I samples have been analyzed and several tens of product nuclei have been identified. For each of those products, neutron-induced reaction rates have been determined. The transmutation power for the (129)I samples is estimated. Experimental results were compared to those calculated with well-known stochastic and deterministic codes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Neutron transfer reactions at large distances

    SciTech Connect

    Rehm, K.E.; Glagola, B.G.; Kutschera, W.; Wolfs, F.L.H.; Wuosmaa, A.H. )

    1993-06-01

    [sup 58]Ni-induced one- and two-neutron transfer reactions have been measured on [sup 232]Th at [ital E][sub lab]=500 MeV. The transfer probabilities at large internuclear distances measured for the deformed [sup 232]Th target are compared with similar data on spherical [sup 208]Pb. For one-neutron transfer reactions good agreement between experiment and the prediction from the tunneling model is observed in both cases. The transfer probabilities for two-neutron transfer reactions deviate from the semiclassical predictions. The disagreement increases at higher bombarding energies. These deviations can be explained by the influence of diffractive effects which become more important at higher bombarding energies.

  15. Comparative assessment of natural radioactivity in fallout samples from Patras and Megalopolis, Greece.

    PubMed

    Papaefthymiou, H; Kritidis, P; Anousis, J; Sarafidou, J

    2005-01-01

    Bulk deposition samples were collected simultaneously from two Greek cities, Patras and Megalopolis, with different emission sources of natural radioactivity, on a monthly basis, during a whole year. Gross beta-activity and 238U- and 232Th-activities were determined in a total of 95 samples of deposited dust. The results were statistically analyzed in order to determine the natural radioactivity levels and their variations in the above cities. No significant difference was found in deposited dust amount between the two cities, while the values of gross beta-, 238U- and 232Th-activities were about 3, 71 and 4 times higher in Megalopolis than in Patras, respectively. This was attributed to the operation of lignite power plants A and B in the vicinity of the city of Megalopolis, while natural radioactivity concentrations in Patras' fallout samples were of natural sources.

  16. Determination of neutron multiplication coefficients for fuel elements irradiated by spallation neutrons

    SciTech Connect

    Bhatia, Chitra; Kumar, V.

    2010-02-15

    A neutron multiplication coefficient, k{sub eff}, has been estimated for spallation neutron flux using the data of spectrum average cross sections of all absorption, fission, and nonelastic reaction channels of {sup 232}Th, {sup 238}U, {sup 235}U, and {sup 233}U fuel elements. It has been revealed that in spallation neutron flux (i) nonfission, nonabsorption reactions play an important role in the calculation of k{sub eff}, (ii) one can obtain a high value of k{sub eff} even for fertile {sup 232}Th fuel, which is hardly possible in a conventional fast reactor, and (iii) spectrum average absorption cross sections of neutron poisons of a conventional reactor are relatively very small.

  17. Radiological investigation of lignite ash. The case of the West Macedonia Lignite Center (Greece)

    SciTech Connect

    Tsikritzis, L.I.; Fotakis, M.; Tzimkas, N.; Tsikritzi, R.; Trikoilidou, E.; Kolovos, N.

    2009-07-01

    This article investigates the natural radioactivity of 26 ash samples, laboratory produced from lignite samples collected in the West Macedonia Lignite Center in Northern Greece. The activity concentrations of {sup 40}K, {sup 235}U, {sup 238}U, {sup 226}Ra, {sup 228}Ra, and 232Th were measured by spectroscopy and found four to five times higher than those in the original lignite samples. The radionuclides transfer factors depend on the characteristics of the combustion process and were found higher for {sup 232}Th, {sup 228}Ra, and 40K, because of their closer affinity with the inorganic fraction of the lignite. Compared with other results found in the published literature, the studied ash has relatively high content in radioactivity, but the resulting radiation dose from the radionuclide emissions in the West Macedonia Lignite Center do not contribute significantly to the total effective dose.

  18. Effect of reducing groundwater on the retardation of redox-sensitive radionuclides

    PubMed Central

    Hu, QH; Zavarin, M; Rose, TP

    2008-01-01

    Laboratory batch sorption experiments were used to investigate variations in the retardation behavior of redox-sensitive radionuclides. Water-rock compositions were designed to simulate subsurface conditions at the Nevada Test Site (NTS), where a suite of radionuclides were deposited as a result of underground nuclear testing. Experimental redox conditions were controlled by varying the oxygen content inside an enclosed glove box and by adding reductants into the testing solutions. Under atmospheric (oxidizing) conditions, radionuclide distribution coefficients varied with the mineralogic composition of the sorbent and the water chemistry. Under reducing conditions, distribution coefficients showed marked increases for 99Tc (from 1.22 at oxidizing to 378 mL/g at mildly reducing conditions) and 237Np (an increase from 4.6 to 930 mL/g) in devitrified tuff, but much smaller variations in alluvium, carbonate rock, and zeolitic tuff. This effect was particularly important for 99Tc, which tends to be mobile under oxidizing conditions. A review of the literature suggests that iodine sorption should decrease under reducing conditions when I- is the predominant species; this was not consistently observed in batch tests. Overall, sorption of U to alluvium, devitrified tuff, and zeolitic tuff under atmospheric conditions was less than in the glove-box tests. However, the mildly reducing conditions achieved here were not likely to result in substantial U(VI) reduction to U(IV). Sorption of Pu was not affected by the decreasing Eh conditions achieved in this study, as the predominant sorbed Pu species in all conditions was expected to be the low-solubility and strongly sorbing Pu(OH)4. Depending on the aquifer lithology, the occurrence of reducing conditions along a groundwater flowpath could potentially contribute to the retardation of redox-sensitive radionuclides 99Tc and 237Np, which are commonly identified as long-term dose contributors in the risk assessment in various

  19. Determination of (236)U and transuranium elements in depleted uranium ammunition by alpha-spectrometry and ICP-MS.

    PubMed

    Desideri, D; Meli, M A; Roselli, C; Testa, C; Boulyga, S F; Becker, J S

    2002-11-01

    It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ((236)U, (239)Pu, (240)Pu, (241)Am, and (237)Np) in the ammunition. In this work the analysis of actinides by alpha-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. (242)Pu and (243)Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri- n-octylamine (TNOA), with a decontamination factor higher than 10(6); after elution plutonium was determined by ICP-MS ((239)Pu and (240)Pu) and alpha-spectrometry ((239+240)Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10(-12) g g(-1) and 2 x 10(-11) g g(-1). The (240)Pu/(239)Pu isotope ratio in one penetrator sample (0.12+/-0.04) was significantly lower than the (240)Pu/(239)Pu ratios found in two soil samples from Kosovo (0.35+/-0.10 and 0.27+/-0.07). (241)Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10(7). The concentration of (241)Am in the penetrator samples was 2.7 x 10(-14) g g(-1) and <9.4 x 10(-15) g g(-1). In addition (237)Np was detected at ultratrace levels. In general, ICP-MS and alpha-spectrometry results were in good agreement. The presence of anthropogenic radionuclides ((236)U, (239)Pu,(240)Pu, (241)Am, and (237)Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible.

  20. Effect of reducing groundwater on the retardation of redox-sensitive radionuclides.

    PubMed

    Hu, Q H; Zavarin, M; Rose, T P

    2008-12-12

    Laboratory batch sorption experiments were used to investigate variations in the retardation behavior of redox-sensitive radionuclides. Water-rock compositions were designed to simulate subsurface conditions at the Nevada Test Site (NTS), where a suite of radionuclides were deposited as a result of underground nuclear testing. Experimental redox conditions were controlled by varying the oxygen content inside an enclosed glove box and by adding reductants into the testing solutions. Under atmospheric (oxidizing) conditions, radionuclide distribution coefficients varied with the mineralogic composition of the sorbent and the water chemistry. Under reducing conditions, distribution coefficients showed marked increases for 99Tc (from 1.22 at oxidizing to 378 mL/g at mildly reducing conditions) and 237Np (an increase from 4.6 to 930 mL/g) in devitrified tuff, but much smaller variations in alluvium, carbonate rock, and zeolitic tuff. This effect was particularly important for 99Tc, which tends to be mobile under oxidizing conditions. A review of the literature suggests that iodine sorption should decrease under reducing conditions when I- is the predominant species; this was not consistently observed in batch tests. Overall, sorption of U to alluvium, devitrified tuff, and zeolitic tuff under atmospheric conditions was less than in the glove-box tests. However, the mildly reducing conditions achieved here were not likely to result in substantial U(VI) reduction to U(IV). Sorption of Pu was not affected by the decreasing Eh conditions achieved in this study, as the predominant sorbed Pu species in all conditions was expected to be the low-solubility and strongly sorbing Pu(OH)4. Depending on the aquifer lithology, the occurrence of reducing conditions along a groundwater flowpath could potentially contribute to the retardation of redox-sensitive radionuclides 99Tc and 237Np, which are commonly identified as long-term dose contributors in the risk assessment in various

  1. Radiological impact of dietary intakes of naturally occurring radionuclides on Pakistani adults.

    PubMed

    Akhter, P; Rahman, K; Orfi, S D; Ahmad, N

    2007-02-01

    Daily dietary intakes of three naturally occurring long-lived radionuclides (232)Th, (238)U and (40)K were estimated for the adult population of Pakistan using neutron activation analysis (NAA), inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), respectively. The daily intakes of (232)Th ranged from 4 to 29 mBq, (238)U ranged from 17 to 82 mBq and (40)K ranged from 51 to 128 Bq. The geometric means of these intakes were 10 mBqd(-1) for (232)Th, 33 mBqd(-1) for (238)U and 78.5 Bqd(-1) for (40)K. The measured values give annual committed effective doses of 0.80, 0.53 and 178.75 microSvyr(-1) for (232)Th, (238)U and (40)K, respectively to Pakistani population. The net radiological impact of these radionuclides is 180.08 microSvyr(-1). This value gives cancer risk factor of 4.5 x 10(-4) and loss of life expectancy of 0.87 days only. Whereas ICRP cancer risk factor for general public is 2.5 x 10(-3) and total risk involve from the all natural radiation sources based on global average annual radiation dose of 2.4 mSvyr(-1) is 6.0 x 10(-3). The estimated cancer risk shows that probability of increase of cancer risk from daily Pakistani diet is only a minor fraction of ICRP values. Therefore, the diet does not pose any significant health hazard and is considered radiologically safe for human consumption.

  2. Naturally occurring radioactive material from the aluminium industry--a case study: the Egyptian Aluminium Company, Nag Hammady, Egypt.

    PubMed

    Abbady, Adel G E; El-Arabi, A M

    2006-12-01

    The activity concentrations and the gamma-absorbed dose rates of the terrestrial naturally occurring radionuclides (226)Ra and (232)Th were determined in samples of bauxite, alumina and aluminium dross tailings industrial waste (used to produce two types of alums) using high purity germanium (HPGe) gamma ray spectrometry. The bauxite and alumina are imported by Egyptalum (The Egyptian Aluminium Company, Nag Hammady, Egypt) from Guinea and India. The activity concentrations in the bauxite range from 29 +/- 1 to 112 +/- 6 Bq kg(-1) for (226)Ra, and 151 +/- 8 to 525 +/- 12 Bq kg(-1) for (232)Th, with mean values of 62 +/- 8 and 378 +/- 50 Bq kg(-1), respectively. With respect to alumina and tail, the mean values are 5.7 +/- 1.1 and 8.4 +/- 0.8 Bq kg(-1) for (226)Ra and 7.2 +/- 1.6 and 10.7 +/- 1.2 Bq kg(-1) for (232)Th. Potassium-40 was not detected in any of the studied samples. The measured activity concentrations of (226)Ra and (232)Th in bauxite are higher than the world average while in alumina and tail they are lower. As a measure of radiation hazard to the occupational workers and members of the public, the Ra equivalent activities and external gamma dose rates due to natural radionuclides at 1 m above the ground surface were calculated. The external gamma-radiation doses received by the Egyptalum workers are 97, 409, 8.5 and 12.7 microSv y(-1) for the Guinean and Indian bauxite, the alumina and tail, respectively, which is well below the recommended allowed dose of 1 mSv y(-1) for non-exposed workers.

  3. 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.

  4. Evaluation of metal and radionuclide data from neutron activation and acid-digestion-based spectrometry analyses of background soils: Significance in environmental restoration

    SciTech Connect

    Lee, S.Y.; Watkins, D.R.; Jackson, B.L.; Schmoyer, R.L.; Lietzke, D.A.; Burgoa, B.B.; Branson, J.T.; Ammons, J.T.

    1995-12-31

    A faster, more cost-effective, and higher-quality data acquisition procedure for natural background-level metals and radionuclides in soils is needed for remedial investigations of contaminated sites. In this project, a total of 120 soil samples were collected from uncontaminated areas on and near the Oak Ridge Reservation. The samples were taken at three different depths and from three different geologic groups to establish background concentrations of metals and radionuclides. The objective of this presentation is to discuss the advantages and disadvantages of neutron activation analysis (NAA) compared with those of acid-digestion-based spectrometry (ADS) methods; the advantages and disadvantages were evaluated from Al, Sb, As, Cr, Co, Fe, Mg, Mn, Hg, K, Ag, {sup 232}Th, {sup 235}U, {sup 238}U, V, and Zn data. The ADS methods used for this project were inductively coupled plasma (ICP), ICP-mass spectrometry (ICP-MS), and alpha spectrometry. The scatter plots showed that the NAA results for As, Co, Fe, Mn, {sup 232}Th, and {sup 238}U are reasonably correlated with the results from the other analytical methods. Compared to NAA, however, the ADS methods underestimated Al, Cr, Mg, K, V, and Zn. The skew distributions were caused by incomplete dissolution of the analytes during acid digestion of the soil samples. Because of the high detection limits of the spectrometric methods, the NAA results and the ADS results for some elements, including Sb, Hg, and Ag, did not show a definite relationship. The NAA results were highly correlated with the alpha spectrometry results for {sup 232}Th and {sup 238}U but poorly correlated for {sup 235}U, probably because of a larger counting error associated with the lower activity of the isotope. The NAA methods, including the delayed neutron counting method, were far superior techniques for quantifying background levels of radionuclides ({sup 232}Th, {sup 235}U, and {sup 238}U) and metals (Al, Cr, Mg, K, V, and Zn) in soils.

  5. Activity concentrations and dose rates from decorative granite countertops.

    PubMed

    Llope, W J

    2011-06-01

    The gamma radiation emitted from a variety of commercial decorative granites available for use in U.S. homes has been measured with portable survey meters as well as an NaI(Th) gamma spectrometer. The (40)K, U-nat, and (232)Th activity concentrations were determined using a full-spectrum analysis. The dose rates that would result from two different arrangements of decorative granite slabs as countertops were explored in simulations involving an adult anthropomorphic phantom.

  6. Distribution of natural and artificial radioactivity in soils, water and tuber crops.

    PubMed

    Darko, Godfred; Faanu, Augustine; Akoto, Osei; Acheampong, Akwasi; Goode, Eric Jude; Gyamfi, Opoku

    2015-06-01

    Activity concentrations of radionuclides in water, soil and tuber crops of a major food-producing area in Ghana were investigated. The average gross alpha and beta activities were 0.021 and 0.094 Bq/L, respectively, and are below the guidelines for drinking water and therefore not expected to pose any significant health risk. The average annual effective dose due to ingestion of radionuclide in water ranged from 20.08 to 53.45 μSv/year. The average activity concentration of (238)U, (232)Th, (40)K and (137)Cs in the soil from different farmlands in the study area was 23.19, 31.10, 143.78 and 2.88 Bq/kg, respectively, which is lower than world averages. The determined absorbed dose rate for the farmlands ranged from 23.63 to 50.51 nGy/year, which is within worldwide range of 18 to 93 nGy/year. The activity concentration of (238)U, (232)Th, (40)K and (137)Cs in cassava ranges from 0.38 to 6.73, 1.82 to 10.32, 17.65 to 41.01 and 0.38 to 1.02 Bq/kg, respectively. Additionally, the activity concentration of (238)U, (232)Th, (40)K and (137)Cs in yam also ranges from 0.47 to 4.89, 0.93 to 5.03, 14.19 to 35.07 and 0.34 to 0.89 Bq/kg, respectively. The average concentration ratio for (238)U, (232)Th and (40)K in yam was 0.12, 0.11 and 0.17, respectively, and in cassava was 0.11, 0.12 and 0.2, respectively. None of the radioactivity is expected to cause significant health problems to human beings.

  7. Tracing dust input to the global ocean using thorium isotopes in marine sediments: ThoroMap

    NASA Astrophysics Data System (ADS)

    Kienast, S. S.; Winckler, G.; Lippold, J.; Albani, S.; Mahowald, N. M.

    2016-10-01

    Continental dust input into the ocean-atmosphere system has significant ramifications for biogeochemical cycles and global climate, yet direct observations of dust deposition in the ocean remain scarce. The long-lived isotope thorium-232 (232Th) is greatly enriched in upper continental crust compared to oceanic crust and mid-ocean ridge basalt-like volcanogenic material. In open ocean sediments, away from fluvial and ice-rafted sources of continental material, 232Th is often assumed to be of predominantly eolian origin. In conjunction with flux normalization based on the particle reactive radioisotope thorium-230 (230Th), 232Th measurements in marine sediments are a promising proxy for dust accumulation in the modern and past ocean. Here we present ThoroMap, a new global data compilation of 230Th-normalized fluxes of 232Th. After careful screening, we derive dust deposition estimates in the global ocean averaged for the late Holocene (0-4 ka) and the Last Glacial Maximum (LGM, 19-23 ka). ThoroMap is compared with dust deposition estimates derived from the Community Climate System Model (CCSM3) and CCSM4, two coupled atmosphere, land, ocean, and sea ice models. Model-data correlation factors are 0.63 (CCSM3) and 0.59 (CCSM4) in the late Holocene and 0.82 (CCSM3) and 0.83 (CCSM4) in the LGM. ThoroMap is the first compilation that is built on a single, specific proxy for dust and that exclusively uses flux-normalization to derive dust deposition rates.

  8. Assessment of natural radioactivity levels and associated dose rates in soil samples from Northern Rajasthan, India.

    PubMed

    Duggal, Vikas; Rani, Asha; Mehra, Rohit; Ramola, R C

    2014-01-01

    The analysis of naturally occurring radionuclides ((226)Ra, (232)Th and (40)K) has been carried out in 40 soil samples collected from four districts of the Northern Rajasthan, India using gamma-ray spectrometry with an NaI(Tl) detector. The activity concentrations of the samples range from 38±9 to 65±11 Bq kg(-1) with a mean value of 52 Bq kg(-1) for (226)Ra, from 8±8 to 32±9 Bq kg(-1) with a mean value of 19 Bq kg(-1) for (232)Th and from 929±185 to 1894±249 Bq kg(-1) with a mean value of 1627 Bq kg(-1) for (40)K. The measured activity concentration of (226)Ra and (40)K in soil was higher and for (232)Th was lower than the worldwide range. Radium equivalent activities were calculated for the soil samples to assess the radiation hazards arising due to the use of these soils in the construction of buildings. The calculated average radium equivalent activity was 205±20 Bq kg(-1), which is less than the recommended limit of 370 Bq kg(-1) by the Organization for Economic Cooperation and Development. The total absorbed dose rate calculated from the activity concentration of (226)Ra, (232)Th and (40)K ranges from 77 to 123 nGy h(-1) with an average value of 103 nGy h(-1). The mean external (Hex) and internal hazard indices (Hin) for the area under study were determined to be 0.55 and 0.69, respectively. The corresponding average annual effective dose was found to be 0.63 mSv.

  9. Natural radioactive nuclides and chemical components in the groundwater of Beni Suef Governate, Middle Egypt.

    PubMed

    Khalil, F A; Amin, Rafat M; El Fayoumi, M A K

    2009-03-01

    Measurements of natural radioactivity in drinking water have been performed in many parts of the world, mostly for assessment of the doses and risk resulting from consuming water. A study of the radionuclide and chemical components in groundwater from Beni Suef Governate, Egypt has been carried out. Fifty water samples were analysed by gamma-ray spectroscopy to determine the (226)Ra, (232)Th and (40)K concentrations; major elements, pH, alkalinity and conductivity were also measured. The activity concentration values ranged from 0.008 to 0.040 Bq l(-1) for (226)Ra, from 0.003 to 0.019 Bq l(-1) for (232)Th and from 0.025 to 0.344 Bq l(-1) for (40)K. The annual ingestion of these radionuclides, using local consumption rates (averaged over the whole population) of 1.5 l d(-1), was estimated to be 8.59, 4.86 and 83.47 Bq y(-1) for (226)Ra, (232)Th and (40)K, respectively. The estimated effective doses from drinking water were found to be 2.4 microSv y(-1) ((226)Ra), 1.1 microSv y(-1) ((232)Th) and 0.5 microSv y(-1) ((40)K). The contribution of these radionuclides to the committed effective dose from a year's consumption of drinking water is therefore estimated to be only 4% of the WHO value (0.1 mSv y(-1)). The moderate pH value is the most important parameter, and there was no observed correlation between natural radioactivity and electrical conductivity or concentrations of major ions.

  10. Environmental radioactivity assessment for Bayburt, Turkey.

    PubMed

    Kucukomeroglu, B; Kurnaz, A; Damla, N; Cevik, U; Celebi, N; Ataksor, B; Taskin, H

    2009-09-01

    This study assesses the results of environmental radioactivity measurements for Bayburt Province in the Eastern Black Sea area of Turkey. Using gamma-ray spectrometry, activity concentrations of the natural radionuclides (226)Ra, (232)Th and (40)K and a fission product (137)Cs were investigated in soil samples. The activity concentrations of (226)Ra, (232)Th and (40)K in various building materials such as sand, cement and marble and in drinking waters were determined. The activity concentrations vary from 16 to 54 Bq kg(-1) for (226)Ra, from 10 to 21 Bq kg(-1) for (232)Th and from 113 to 542 Bq kg(-1) for (40)K in building materials. The mean specific activity concentrations of (226)Ra, (232)Th and (40)K in drinking waters were 93, 30 and 504 mBq l(-1), respectively. The concentrations of gross alpha and beta radioactivity in drinking water samples collected from four different sampling stations have been determined. The results show that the gross alpha and beta activities are lower than the screening levels given by the World Health Organization (WHO), which are a maximum contaminant level of 0.5 Bq l(-1) and 1.0 Bq l(-1) gross alpha and beta radioactivity, respectively, in drinking water. Indoor radon measurements were made in 44 dwellings in Bayburt by using Cr-39 detectors. Radon concentrations in dwellings in Bayburt varied from 17 to 125 Bq m(-3) and the average value was 56 Bq m(-3). The results obtained in this study indicate that the region has a background radiation level that is within the typical natural range and shows no significant departures from other parts of the country.

  11. Radionuclide distribution of Holocene sediments and its effects on the habitat of recent foraminifers: A case study from the Western Marmara Sea (Turkey)

    NASA Astrophysics Data System (ADS)

    Ünal Yumun, Zeki; Kam, Erol; Murat Kılıc, Ali

    2017-04-01

    ABSTRACT Radionuclides cause radioactive contamination in aquatic environments just as other non-biodegradable pollutants, such as heavy metals, sink to the seafloor and accumulate in the sediments. These radioactive pollutants especially affect benthic foraminifera living on the sediment surface or in the sediments in the seafloor. Foraminifera were used as bioindicators to analyze the effect of radioactivity pollution on ecosystems. In this study, we have investigated natural and artificial radionuclide (232Th, 226Ra, 40K and 137Cs) distribution in sediment samples taken in the living areas of benthic foraminifera in the Western Marmara Sea by means of gamma spectrometry. Accordingly, 29 core samples taken in 2016 from depths of about 20-35 m close to the shores of the Marmara Sea were used. Core samples representing the pollution of the study area were collected at locations such as discharge points for domestic and industrial areas, port locations, and others. Other samples were taken from areas unaffected or less affected by pollution. The radionuclide concentration activity values in the sediment samples obtained from the locations, in Bq/kg, were 137Cs, 0.9-9.4; 232Th, 18.9-86; 226Ra, 10-50; 40K, 24.4-670. These values were compared with the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) data, and an environmental analysis was carried out. The 226Ra series, the 232Th series, and the 40K radionuclides accumulate naturally, and they are also increasing continuously due to anthropogenic pollution. Although the 226Ra values obtained throughout the study areas remained within normal limits according to the UNSCEAR values, the 40K and 232Th series values were found to be higher in almost all locations. According to these results, the main causes of radioactive pollution in the investigation area are agricultural and mining activities. Keywords: Ra-226, Th-232, K-40, Cs-137, radionuclide, Western Marmara Sea, Foraminifera

  12. Thorium-230 dating of natural waters at the Nevada Test Site

    SciTech Connect

    Bakhtiar, S.N.

    1990-01-01

    Radiocarbon determinations have been used in the past to estimate the ages of groundwater from the Paleozoic aquifer underlying the Nevada Test Site and adjacent areas. We measured the concentrations of {sup 230}Th, {sup 232}Th, {sup 234}U and {sup 238}U in several water samples taken from the wells and spring at the Nevada Test Site and calculated the {sup 230}Th ages. 2 refs.

  13. Gamma-spectrometric measurement of radioactivity in agricultural soils of the Lombardia region, northern Italy.

    PubMed

    Guidotti, Laura; Carini, Franca; Rossi, Riccardo; Gatti, Marina; Cenci, Roberto M; Beone, Gian Maria

    2015-04-01

    This work is part of a wider monitoring project of the agricultural soils in Lombardia, which aims to build a database of topsoil properties and the potentially toxic elements, organic pollutants and gamma emitting radionuclides that the topsoils contain. A total of 156 agricultural soils were sampled according to the LUCAS (Land Use/Cover Area frame statistical Survey) standard procedure. The aim was to provide a baseline to document the conditions present at the time of sampling. The results of the project concerning soil radioactivity are presented here. The aim was to assess the content of (238)U, (232)Th, (137)Cs and (40)K by measuring soil samples by gamma spectrometry. (238)U, (232)Th and (40)K activities range 24-231, 20-70, and 242-1434 Bq kg(-1) respectively. The geographic distribution of (238)U reflects the geophysical framework of the Lombardia region: the soils with high content of uranium are distributed for the most part in the South Alpine belt, where the presence of magmatic rocks is widespread. These soils show an higher activity of (238)U than of (232)Th. The (238)U activities become lower than (232)Th when soils are located in the plain, originating from basic sedimentary rocks. (137)Cs activity ranges 0.4-86.8 kBq m(-2). The lowest activity of (137)Cs is in the plain, whereas the highest is in the North on soils kept as lawn or pasture. The (137)Cs activity of some samples suggests the presence of accumulation processes that lead to (137)Cs enriched soils. This is the first survey of gamma emitting radionuclides in Lombardia that is based on the LUCAS standard sampling. The results from this monitoring campaign are important for the human radiation exposure and provide the zero point, which will be useful for assessing future effects due to external factors such as human activities.

  14. Soudan Low Background Counting Facility (SOLO)

    SciTech Connect

    Attisha, Michael; Viveiros, Luiz de; Gaitksell, Richard; Thompson, John-Paul

    2005-09-08

    The Soudan Low Background Counting Facility (SOLO) has been in operation at the Soudan Mine, MN since March 2003. In the past two years, we have gamma-screened samples for the Majorana, CDMS and XENON experiments. With individual sample exposure times of up to two weeks we have measured sample contamination down to the 0.1 ppb level for 238U / 232Th, and down to the 0.25 ppm level for 40K.

  15. Study of Natural Radioactivity in Coal Samples of Baganuur Coal Mine, Mongolia

    SciTech Connect

    Altangerel, M.; Norov, N.; Altangerel, D.

    2009-03-31

    Coal and soil samples from Baganuur Coal Mine (BCM) of Mongolia have been investigated. The activities of {sup 226}Ra, {sup 232}Th and {sup 40}K have been measured by gamma-ray spectrometry using shielded HPGe detector. Contents of natural radionuclide elements (U, Th and K) have been determined. Also the activities and contents of radionuclide of ashes were determined which generated in Thermal Power Plant 3 of Ulaanbaatar from coal supplied from BCM.

  16. Influence of entrance channel on the production of hassium isotopes

    NASA Astrophysics Data System (ADS)

    Hong, Juhee; Adamian, G. G.; Antonenko, N. V.

    2015-07-01

    The production of hassium isotopes Hs-271266 in various reactions 22Ne+249Cf,Mg,2625+248Cm,30Si+244Pu,S,3634+238U,40Ar+232Th , and 48Ca+226Ra is studied within the dinuclear system model. The experimental excitation functions of the isotopes 266 -271Hs are well described and predictions are made for future experiments.

  17. Generation of thorium ions by laser ablation and inductively coupled plasma techniques for optical nuclear spectroscopy

    NASA Astrophysics Data System (ADS)

    Troyan, V. I.; Borisyuk, P. V.; Khalitov, R. R.; Krasavin, A. V.; Lebedinskii, Yu Yu; Palchikov, V. G.; Poteshin, S. S.; Sysoev, A. A.; Yakovlev, V. P.

    2013-10-01

    Single- and double-charged 232Th and 229Th ions were produced by laser ablation of solid-state thorium compounds and by inductively coupled plasma techniques with mass-spectrometry analysis from liquid solutions of thorium. The latter method was found to be more applicable for producing ions of radioactive 229Th for laser experiments when searching for the energy value of the isomeric nuclear transition.

  18. Enrichment and particle size dependence of polonium and other naturally occurring radionuclides in coal ash.

    PubMed

    Sahu, S K; Tiwari, M; Bhangare, R C; Pandit, G G

    2014-12-01

    Coal fired thermal power contributes 70% of power in India. Coal fired power generation results in huge amounts of fly ash and bottom ash of varying properties. Coal, which contains the naturally occurring radionuclides, on burning results in enrichment of these radionuclides in the ashes. In the present study, coal, bottom ash and fly ash samples collected from six coal-fired power plants in India were measured for (210)Po using alpha spectrometry and for natural U, (226)Ra, (232)Th and (40)K by an HPGe γ-ray spectrometer. (210)Po in fly ash ranged from 25.7 to 70 Bq/kg with a mean value of 40.5 Bq/kg. The range and mean activities of (238)U, (226)Ra, (232)Th, (40)K in fly ash were 38.5-101 (78.1), 60-105.7 (79), 20-125 (61.7) and 43.6-200 (100) Bq/kg respectively. Fly ash and bottom ash contains two to five times more natural radionuclides than feed coal. The results were compared with the available data from earlier studies in other countries. The effect of particle size on enrichment factor of the nuclides in fly ash was studied. (210)Po showed the largest size dependence with its concentration favoring the smaller particle size while (232)Th showed least size dependence. (238)U and (226)Ra showed behavior intermediate to that of (210)Po and (232)Th. Also the correlation between sulfur content of the feed coal and activity of (210)Po was investigated. Increased sulfur content in feed coal enhanced enrichment of (210)Po in ash. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Radioactivity in rocks and soil and interaction with groundwater in an arid region

    NASA Astrophysics Data System (ADS)

    Alshamsi, Dalal; Murad, Ahmed; Aldahan, Ala; Hou, Xiaolin; El Saiy, Ayman

    2014-05-01

    Interaction of groundwater with soil and rocks changes the chemical composition of the water both spatially and temporally. In arid regions, surficial recharge of groundwater is generally limited to sporadic rainfall events which may cause rapid interaction between the recharge water and the aquifers materials. Among the elements that commonly increase in concentration as groundwater interact with the aquifer materials are the radioactive elements such as uranium and thorium and their decay chain products. Here, we present data on 235U, 238U, 232Th as well as 137Cs in some sediments and rock aquifers located in the United Arab Emirates (UAE) in southeastern Arabian Peninsula. The Quaternary sediments are composed of silt, sand and gravel with varying proportions of quartz, carbonates, feldspars, evaporites, while the carbonates are mainly limestones, dolomitic limestones, dolomite and calcareous mudstones. These carbonate rocks cover ages extending from 10-230 Myr. After complete digestion using fluoric and nitric acids and chemical separation, the isotopes were measured using ICP-MS. The 235U, 238U and 232Th concentrations ranges are 2.66-32.5 ng/g, 354.7-4453 ng/g and 13.2-1367 ng/g respectively in the carbonate rocks. In the sediments the concentrations are 4.6-17.5 ng/g for 235U, 631.7-2406 ng/g for 238U and 25.6-799.6 ng/g for 232Th. Although it is difficult to quantify the amounts of uranium isotopes that enter the hydrological system from the aquifers, it seems that in the presence of carboxyl ions, uranium forms highly soluble complexes which can be transported to large distances in groundwater. The variations in 232Th concentrations are probably controlled by the availability of sulfate salt rocks (like gypsum) interacting with thorium and forming soluble thorium compounds which can also explain the highly variable concentrations in groundwater.

  20. Artificial and natural radionuclides in soils of the southern and middle taiga zones of Komi Republic

    NASA Astrophysics Data System (ADS)

    Beznosikov, V. A.; Lodygin, E. D.; Shuktomova, I. I.

    2017-07-01

    Specific activities of artificial (137Cs, 90Sr) and natural (40K, 232Th, 226Ra) radionuclides in background soils of southern and middle taiga of Komi Republic have been estimated with consideration for the landscape-geochemical features of the territory. It has been shown that their accumulation and migration in soils are determined by the following factors: position in relief, texture, and organic matter content. No anomalous zones with increased contents of radionuclides in soils have been revealed.

  1. Assessment of natural radioactivity levels in rocks and their relationships with the geological structure of Johor state, Malaysia.

    PubMed

    Alnour, I A; Wagiran, H; Ibrahim, N; Hamzah, S; Elias, M S; Laili, Z; Omar, M

    2014-01-01

    The distribution of natural radionuclides ((238)U, (232)Th and (40)K) and their radiological hazard effect in rocks collected from the state of Johor, Malaysia were determined by gamma spectroscopy using a high-purity germanium detector. The highest values of (238)U, (232)Th and (40)K activity concentrations (67±6, 85±7 and 722±18 Bg kg(-1), respectively) were observed in the granite rock. The lowest concentrations of (238)U and (232)Th (2±0.1 Bq kg(-1) for (238)U and 2±0.1 Bq kg(-1) for (232)Th) were observed in gabbro rock. The lowest concentration of (40)K (45±2 Bq kg(-1)) was detected in sandstone. The radium equivalent activity concentrations for all rock samples investigated were lower than the internationally accepted value of 370 Bq kg(-1). The highest value of radium equivalent in the present study (239±17 Bq kg(-1)) was recorded in the area of granite belonging to an acid intrusive rock geological structure. The absorbed dose rate was found to range from 4 to 112 nGy h(-1). The effective dose ranged from 5 to 138 μSv h(-1). The internal and external hazard index values were given in results lower than unity. The purpose of this study is to provide information related to radioactivity background levels and the effects of radiation on residents in the study area under investigation. Moreover, the relationships between the radioactivity levels in the rocks within the geological structure of the studied area are discussed.

  2. 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.

  3. Assessments of radioactivity concentration of natural radionuclides and radiological hazard indices in sediment samples from the East coast of Tamilnadu, India with statistical approach.

    PubMed

    Ravisankar, R; Chandramohan, J; Chandrasekaran, A; Prince Prakash Jebakumar, J; Vijayalakshmi, I; Vijayagopal, P; Venkatraman, B

    2015-08-15

    This paper reports on the distribution of three natural radionuclides (238)U, (232)Th and (40)K in coastal sediments from Pattipulam to Devanampattinam along the East coast of Tamilnadu to establish baseline data for future environmental monitoring. Sediment samples were collected by a Peterson grab samples from 10m water depth parallel to the shore line. Concentration of natural radionuclides were determined using a NaI(Tl) detector based γ-spectrometry. The mean activity concentration is ⩽2.21, 14.29 and 360.23Bqkg(-1) for (238)U, (232)Th and (40)K, respectively. The average activity of (232)Th, (238)U and (40)K is lower when compared to the world average value. Radiological hazard parameters were estimated based on the activity concentrations of (238)U, (232)Th and (40)K to find out any radiation hazard associated with the sediments. The radiological hazard parameters such as radium equivalent activity (Raeq), absorbed gamma dose rates in air (DR), the annual gonadal dose equivalent (AGDE), annual effective dose equivalent (AEDE), external hazard index (Hex) internal hazard index (Hin), activity utilization index (AUI) and excess lifetime cancer (ELCR) associated with the radionuclides were calculated and compared with internationally approved values and the recommended safety limits. Pearson correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied in order to recognize and classify radiological parameters in sediments collected at 22 sites on East coast of Tamilnadu. The values of radiation hazard parameters were comparable to the world averages and below the recommended values. Therefore, coastal sediments do not to pose any significant radiological health risk to the people living in nearby areas along East coast of Tamilnadu. The data obtained in this study will serve as a baseline data in natural radionuclide concentration in sediments along the coastal East coast of Tamilnadu. Copyright © 2015 Elsevier

  4. Spectral interference corrections for the measurement of (238)U in materials rich in thorium by a high resolution gamma-ray spectrometry.

    PubMed

    Yücel, H; Solmaz, A N; Köse, E; Bor, D

    2009-11-01

    In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of (234)Th and 1001.0 keV of (234m)Pa, which are often used in the measurement of (238)U activity by the gamma-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the gamma-rays overlapping the analytical peaks, due to the contribution of (232)Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference gamma-rays of (232)Th and (235)U to the mixed peak at 63.3 keV of (234)Th ((238)U) leads to the remarkably large systematic influence of 0.8-122% in the measured (238)U activity, but in case of ignoring the contribution of (232)Th via the interference gamma-ray at 1000.7 keV of (228)Ac to the mixed peak at 1001 keV of (234m)Pa ((238)U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate (238)U activity results. Additionally, if one ignores the contribution of (232)Th to both (238)U and (40)K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be ~6% and ~1% via the analytical peaks at 63.3 and 1001 keV for measurement of the (238)U activity, respectively.

  5. Measurement of natural radioactivity in beach sands from Rizhao bathing beach, China.

    PubMed

    Lu, Xinwei; Zhang, Xiaolan

    2008-01-01

    The natural radioactivity of (226)Ra, (232)Th and (40)K was determined for beach sand samples collected from Rizhao bathing beach, China, using gamma ray spectrometry. The measured activity in beach sand ranges from 7.6 to 17.2, 7.8 to 25.1 and 883.4 to 1313.6 Bq kg(-1) for (226)Ra, (232)Th and (40)K with mean values of 12.0, 15.2 and 1079.2 Bq kg(-1), respectively. The activity concentrations of (226)Ra and (232)Th in beach sands are lower, while (40)K is higher than the world average. The radium equivalent activity in all beach sand samples is lower than the safe limit set in the OECD report (370 Bq kg(-1)). The values of the external hazard index are less than unity. The mean outdoor air absorbed dose rate is 59.8 nGy h(-1) and the corresponding outdoor effective dose rate is 0.073 mSv y(-1).

  6. Radioactivity concentration in soil samples in the southern part of the West Bank, Palestine.

    PubMed

    Dabayneh, K M; Mashal, L A; Hasan, F I

    2008-01-01

    The activity concentrations of naturally occurring radioactive materials such as (238)U, (232)Th and (40)K were measured for 38 soil samples collected from diverse zones in the southern area of West Bank, Palestine using gamma-ray spectroscopy. The measured activities of (238)U, (232)Th and (40)K were found to range from 32.9 to 104.7, 14.5 to 76.6 and 297 to 962 Bq kg(-1) with averages value of 68.7, 48.0 and 630 Bq kg(-1), respectively. The obtained values of activity concentrations are higher than the world average of 35, 30 and 500 Bq kg(-1) for (238)U, (232)Th and (40)K, respectively. The measured (137)Cs activity concentration was found to range from 1.8 to 36.1 Bq kg(-1) with an average value of 8.5 Bq kg(-1). The detected activities were attributed to the fallout of (137)Cs, which is the only man-made radionuclide. The calculated average of the total gamma-radiation dose rate of natural radionuclides, (137)Cs and cosmic radiation is 121.4 nGy h(-1). The radium equivalent activity (R(aeq)), dose rate (D(r)), external hazard index (H(ex)) and radioactivity level index (I(gamma)) in all samples are presented. Some values were found to be in the range of worldwide values, whereas others were above the worldwide values.

  7. Measurement of natural radioactivity in building materials used in Urumqi, China.

    PubMed

    Ding, Xiang; Lu, Xinwei; Zhao, Caifeng; Yang, Guang; Li, Nan

    2013-07-01

    Building materials contain natural radionuclides (226)Ra, (232)Th and (40)K, which cause direct radiation exposure of the public. The concentrations of (226)Ra, (232)Th and (40)K in commonly used building materials of Urumqi, China have been analysed using gamma-ray spectrometry. The concentrations of (226)Ra, (40)K and (232)Th in the studied building materials range from 19.8 to 87.4, from 273.3 to 981.2 and from 11.6 to 47.7 Bq kg(-1), respectively. The radium equivalent activity (Raeq), gamma index (Iγ) and alpha index (Iα) were calculated to assess the radiation hazards to people living in dwellings made of the materials studied. The calculated Raeq values of all the building materials are lower than the limit of 370 Bq kg(-1) for building materials. The values of Iγ and Iα of all the building materials are less than unity. The study shows that these materials may be safely used as construction materials and do not pose significant radiation hazards.

  8. Radioactivity of sand, groundwater and wild plants in northeast Sinai, Egypt.

    PubMed

    Ramadan, Khaled A; Seddeek, Mostafa K; Nijim, Abdelkareem; Sharshar, Taher; Badran, Hussein M

    2011-12-01

    The radioactivity levels are poorly studied in non-coastal arid regions. For this reason, 38 locations covering an area of about 350 km(2) in northeast Sinai, Egypt, were investigated by γ-ray spectroscopy. Moderately significant correlations among (238)U, (234)Th, and (226)Ra isotopes and low significant correlations between the concentrations of (238)U-series and (232)Th in sand were obtained. No evidence of correlation was found between the concentrations of radioisotopes and pH, grain size, total organic matter content, bicarbonate or calcium carbonate concentrations of the sand samples. The mean values of soil-to-plant transfer factor were 0.15, 0.18, 1.52 and 0.74 for (226)Ra, (232)Th, (40)K, and (137)Cs, respectively. The range of concentrations of (226)Ra,( 232)Th, and (40)K in water samples collected from five wells were<0.4-0.16,<0.4-0.13, and<0.15-1.62 Bq l(-1), respectively. The mean absorbed dose rate in outdoor air at a height of 1 m above the ground surface for the sand samples was 19.4 nGy h(-1). The Ra(eq) activities of the sands are lower than the recommended maximum value of 370 Bq kg(-1) criterion limit for building materials.

  9. Analytical evaluation of natural radionuclides and their radioactive equilibrium in raw materials and by-products.

    PubMed

    Ji, Young-Yong; Chung, Kun Ho; Lim, Jong-Myoung; Kim, Chang-Jong; Jang, Mee; Kang, Mun Ja; Park, Sang Tae

    2015-03-01

    An investigation into the distribution of natural radionuclides and radioactive secular equilibrium in raw materials and by-products in a domestic distribution was conducted to deduce the optimum conditions for the analytical evaluation of natural radionuclides for (238)U, (226)Ra, and (232)Th using a gamma-ray spectrometer and inductively coupled plasma mass spectrometer (ICP-MS). The range of the specific activities of natural radionuclides was first evaluated by analyzing (228)Ac and (214)Bi, which are (232)Th and (226)Ra indicators, respectively, in about 100 samples of raw materials and by-products through a gamma-ray spectrometer. From further experiments using several samples selected based on the results of the distribution of natural radionuclides, the validation of their analytical evaluations for the indirect measurements using a gamma-ray spectrometer and direct measurements using ICP-MS was assured by comparing their results. Chemically processed products from the raw materials, such as Zr sand and ceramic balls, were generally shown for the type of bead and particularly analyzed showing a definite disequilibrium with above a 50% difference between (238)U and (226)Ra in the uranium series and (232)Th and (228)Ra in the thorium series.

  10. Radiological study of Mersing District, Johor, Malaysia

    NASA Astrophysics Data System (ADS)

    Saleh, Muneer Aziz; Ramli, Ahmad Termizi; Alajerami, Yasser; Aliyu, Abubakar Sadiq; Bt Basri, Nor Afifah

    2013-04-01

    A potential site has been selected for a nuclear power plant (NPP) in Mersing District of Malaysia. This study aims at providing the base line data of this district for the first time, in line with the International Atomic Energy Agency (IAEA) for NPP sitting criteria. The mean dose rate, mean population weighted dose rate and annual effective dose are found to be 140 nGy h-1, 0.836 mSv y-1 and 0.857 mSv, respectively. A hyper Purity Germanium Detector (HPGe) is used in determining the activity concentrations of 232Th, 226Ra and 40K. The activity concentration ranges from 16±1 to 410±15 Bq kg-1 for 232Th, 17±1 to 271±8 Bq kg-1 for 226Ra and 13±3 to 1434±57 Bq kg-1 for 40K. In addition, a Low Background Alpha Beta Series 5 XLB Automatic was used in the determination of gross alpha and gross beta activity. The result ranges from 202±50 to 2325±466 Bq kg-1 for gross alpha and 164±17 to 2447±103 Bq kg-1 for gross beta. Contour maps were produced for isodose, activity concentration of 232Th, 226Ra, 40K, gross alpha and gross beta for the study area. The results are compared with UNSCEAR (2000).

  11. Anthropogenic and naturally occurring radionuclide content in near surface air in Cáceres (Spain).

    PubMed

    Baeza, Antonio; Rodríguez-Perulero, Antonio; Guillén, Javier

    2016-12-01

    The anthropogenic ((137)Cs, (90)Sr, (239+240)Pu and (241)Am) and naturally occurring radionuclide ((40)K, (234,238)U, (228,230,232)Th, (226)Ra and (210)Pb) content in near surface air present seasonal variations related to natural processes, such as soil erosion, resuspension of fine particles of soil and radon exhalation from soil ((210)Pb). The objective is to analyze seasonal variations of their concentrations and compare with radiological events (Fukushima fallout and wild fire) in a location without any known source of anthropogenic radionuclides. The (210)Pb, (40)K, and (137)Cs presented annual variations, with maximum activity levels in summer. Solar radiation and rainfall were correlated with (210)Pb and (40)K. The (234,238)U, (228,230,232)Th, (226)Ra, (137)Cs and (90)Sr presented positive correlation with monthly mean values of temperature. The ratio (90)Sr/(137)Cs was within the range of those reported for soils in Spain. Finally, the maximal effective dose rate was estimated to be 37 and 88 μSv/y for infants and adults, respectively, well below 1 mSv/y reference level. The main contributor to effective dose was (210)Pb, about 92%, followed by: (210)Pb ≫ (228,230,232)Th > (226)Ra, (234,238)U > (7)Be, (239+240)Pu > (40)K, (90)Sr > (137)Cs > (22)Na.

  12. Clay Mineral: Radiological Characterization

    NASA Astrophysics Data System (ADS)

    Cotomácio, J. G.; Silva, P. S. C.; Mazzilli, B. P.

    2008-08-01

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and 40K in these clay minerals. The objective of this work is to determine the concentrations of 238U, 232Th, 226Ra, 228Ra, 210Pb and 40K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of 238U and 232Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for 226Ra, 228Ra, 210Pb and 40K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906±340 Bq kg-1 for 40K, 40±9 Bq kg-1 for 226Ra, 75±9 Bq kg-1 for 228Ra, 197±38 Bq kg-1 for 210Pb, 51±26 Bq kg-1 for 238U and 55±24 Bq kg-1 for 232Th, considering both kinds of clay.

  13. Natural Radioactivity in Soil and Water from Likuyu Village in the Neighborhood of Mkuju Uranium Deposit

    PubMed Central

    Mohammed, Najat K.; Mazunga, Mohamed S.

    2013-01-01

    The discovery of high concentration uranium deposit at Mkuju, southern part of Tanzania, has brought concern about the levels of natural radioactivity at villages in the neighborhood of the deposit. This study determined the radioactivity levels of 30 soil samples and 20 water samples from Likuyu village which is 54 km east of the uranium deposit. The concentrations of the natural radionuclides 238U, 232Th, and 40K were determined using low level gamma spectrometry of the Tanzania Atomic Energy Commission (TAEC) Laboratory in Arusha. The average radioactivity concentrations obtained in soil samples for 238U (51.7 Bq/kg), 232Th (36.4 Bq/kg), and 40K (564.3 Bq/kg) were higher than the worldwide average concentrations value of these radionuclides reported by UNSCEAR, 2000. The average activity concentration value of 238U (2.35 Bq/L) and 232Th (1.85 Bq/L) in water samples was similar and comparable to their mean concentrations in the control sample collected from Nduluma River in Arusha. PMID:23781247

  14. [Study on the ecological association between natural radioactivity and childhood leukemia in Guangdong province].

    PubMed

    Ma, Jin-Xiang; Lei, Yi-Xiong; Ye, Tie-Zhen

    2008-04-01

    This study was undertaken to evaluate the ecological association between terrestrial natural radionuclide, indoor radon concentration, natural radioactivity and leukemia incidence among children under 18 years of age. Data were gathered from the disease surveillance program and literature reading while software SPSS 13.0 was used to calculate the Spearman's correlation. The incidence rates of childhood (0-18 year) leukemia showed significant differences in different places with the highest as 3.13/10(5) in Jiangmen area and the lowest as 0.42/10(5) in Maoming area. The incidence in Jiangmen was 7.45 times higher than that in Maoming. There was a rank correlation between the incidence of childhood leukemia and the mean concentrations of natural radio-nuclides in soil (226Ra and 232Th), with a positive correlation observed for overall leukemia (r(s) = 0.70, P = 0.011; r(s) = 0.66, P= 0.02 for 226 Ra and 232Th respectively) and acute lymphoblastic leukemia (ALL) (r(s) = 0.66, P = 0.019; r(s) = 0.64, P = 0.025 for 226 Ra and 232Th respectively). Associations between the incidence of childhood leukemia and the indoor gamma radiation dose rate, the total annual average effective dose equivalent from natural background radiationwere also analyzed (both r(s) = 0.59, P = 0.042). The natural radioactivity was likely to be a causative factor for childhood leukemia in Guangdong.

  15. Assessment of radiological hazard parameters due to natural radioactivity in soils from granite-rich regions in Kütahya Province, Turkey.

    PubMed

    Sahin, Latife; Hafızoğlu, Nurgül; Çetinkaya, Hakan; Manisa, Kaan; Bozkurt, Engin; Biçer, Ahmet

    2017-05-01

    The analysis of natural radioactivity from (238)U, (232)Th and (40)K in 357 soil samples collected from the province of Kütahya was carried out using a NaI(Tl) gamma-ray spectroscopy system at the Nuclear Physics Research Laboratory, Dumlupınar University, Kütahya, Turkey. The specific activities of (238)U, (232)Th and (40)K in the soil samples were evaluated. From the activity concentrations of (238)U, (232)Th and (40)K, the total absorbed outdoor gamma-ray dose rates and the corresponding annual effective dose rates were determined. The corresponding values of the external and internal hazard indices of all the soil samples were also calculated. The external gamma-ray dose rate at 1 m above the ground was directly measured at each collected soil sample location. The results obtained in this study were compared within the limits of values obtained in other cities of Turkey, those in other countries. Radiological maps of Kütahya Province were constructed from the results of this study.

  16. Implications of modelled radioactivity measurements along coastal Odisha, Eastern India for heavy mineral resources

    NASA Astrophysics Data System (ADS)

    Ghosal, S.; Agrahari, S.; Guin, R.; Sengupta, D.

    2017-01-01

    A radioelemental assemblage assessment of two beaches of Odisha is performed for the first time. The radiation is measured in two ways, both on field with the help of a hand held environmental survey meter and in the laboratory, where the concentrations of radionuclide's 238U, 232Th and 4K have been determined with the help of High Purity Germanium detector (HPGe). Mineralogical analysis of selected samples has been performed with the help of X-Ray Fluorescence Spectrometry (XRF). A marked difference between the concentration of Uranium (274 Bq kg-1) and Thorium (2489 Bq kg-1) is observed and discussed based on the geology of the area. The placer deposits showing an enrichment of thorium can be an important source of nuclear fuel for the thorium based nuclear reactors. The ratio of thorium and uranium concentrations gives us an idea about the coastal processes associated with the beach. Statistical analysis of the data shows a positive correlation between 238U and 232Th and a strong negative correlation is indicated between 4 K and 238U, 232Th. A cross plot between the equivalent thorium and the equivalent uranium and the equivalent thorium and potassium, represents the nature of deposition and its association with the heavy mineral along with the radioactive elements. Heavy minerals exhibit an increasing trend towards Northeast-Southwest along the south eastern coast of India.

  17. Radioactivity levels and heavy metals in the urban soil of Central Serbia.

    PubMed

    Milenkovic, B; Stajic, J M; Gulan, Lj; Zeremski, T; Nikezic, D

    2015-11-01

    Radioactivity concentrations and heavy metal content were measured in soil samples collected from the area of Kragujevac, one of the largest cities in Serbia. The specific activities of (226)Ra, (232)Th, (40)K and (137)Cs in 30 samples were measured by gamma spectrometry using an HPGe semiconductor detector. The average values ± standard deviations were 33.5 ± 8.2, 50.3 ± 10.6, 425.8 ± 75.7 and 40.2 ± 26.3 Bq kg(-1), respectively. The activity concentrations of (226)Ra, (232)Th and (137)Cs have shown normal distribution. The annual effective doses, radium equivalent activities, external hazard indexes and excess lifetime cancer risk were also estimated. A RAD7 device was used for measuring radon exhalation rates from several samples with highest content of (226)Ra. The concentrations of As, Co, Cr, Cu, Mn, Ni, Pb and Zn were measured, as well as their EDTA extractable concentrations. Wide ranges of values were obtained, especially for Cr, Mn, Ni, Pb and Zn. The absence of normal distribution indicates anthropogenic origin of Cr, Ni, Pb and Zn. Correlations between radionuclide activities, heavy metal contents and physicochemical properties of analysed soil were determined by Spearman correlation coefficient. Strong positive correlation between (226)Ra and (232)Th was found.

  18. Extreme U-Th disequilibrium in rift-related basalts, rhyolites and granophyric granite and the timescale of rhyolite generation, intrusion and crystallization at Alid volcanic center, Eritrea

    USGS Publications Warehouse

    Lowenstern, J. B.; Charlier, B.L.A.; Clynne, M.A.; Wooden, J.L.

    2006-01-01

    Rhyolite pumices and co-erupted granophyric (granite) xenoliths yield evidence for rapid magma generation and crystallization prior to their eruption at 15·2 ± 2·9 ka at the Alid volcanic center in the Danikil Depression, Eritrea. Whole-rock U and Th isotopic analyses show 230Th excesses up to 50% in basalts <10 000 years old from the surrounding Oss lava fields. The 15 ka rhyolites also have 30–40% 230Th excesses. Similarity in U–Th disequilibrium, and in Sr, Nd, and Pb isotopic values, implies that the rhyolites are mostly differentiated from the local basaltic magma. Given the (230Th/232Th) ratio of the young basalts, and presumably the underlying mantle, the (230Th/232Th) ratio of the rhyolites upon eruption could be generated by in situ decay in about 50 000 years. Limited (∼5%) assimilation of old crust would hasten the lowering of (230Th/232Th) and allow the process to take place in as little as 30 000 years. Final crystallization of the Alid granophyre occurred rapidly and at shallow depths at ∼20–25 ka, as confirmed by analyses of mineral separates and ion microprobe data on individual zircons. Evidently, 30 000–50 000 years were required for extraction of basalt from its mantle source region, subsequent crystallization and melt extraction to form silicic magmas, and final crystallization of the shallow intrusion. The granophyre was then ejected during eruption of the comagmatic rhyolites.

  19. ASSESSMENT OF AGE-DEPENDENT RADIATION DOSE DUE TO INTAKE OF URANIUM AND THORIUM IN DRINKING WATER FROM SIKAR DISTRICT, RAJASTHAN, INDIA.

    PubMed

    Duggal, Vikas; Rani, Asha; Balaram, V

    2016-10-01

    The concentrations of (238)U and (232)Th have been determined in drinking water samples collected from the Sikar district of Rajasthan State, India. The samples have been analysed by using high-resolution inductively coupled plasma mass spectrometry. (238)U content in water samples ranged from 8.20 to 202.63 µg l(-1) and (232)Th content ranged from 0.57 to 1.46 µg l(-1) The measured (238)U content in 25 % of the analysed samples exceeded the World Health Organization (WHO) and United States Environmental Protection Agency drinking water guidelines of 30 µg l(-1) and 12.5 % of the samples exceeded the 60 µg l(-1) Indian maximum acceptable concentration recommended by the Atomic Energy Regulatory Board, India. The annual effective doses (µSv y(-1)) due to ingestion of (238)U and (232)Th for different age groups were also calculated. The results compared with the recommended value reported by the WHO. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Distribution of low-level natural radioactivity in a populated marine region of the Eastern Mediterranean Sea.

    PubMed

    Evangeliou, Nikolaos; Florou, Heleny; Kritidis, Panayotis

    2012-12-01

    The levels of natural radioactivity have been evaluated in the water column of an eastern Mediterranean region (Saronikos Gulf), with respect to the relevant environmental parameters. A novel methodology was used for the determination of natural radionuclides, which substitutes the time-consuming radiochemical analysis, based on an in situ sample preconcentration using ion-selective manganese fibres placed on pumping systems. With regard to the results obtained, (238)U-series radionuclides were found at the same level or lower than those observed previously in Mediterranean regions indicating the absence of technologically enhanced naturally occurring radioactive material (TENORM) activities in the area. Similar results were observed for the (232)Th-series radionuclides and (40)K in the water column in comparison with the relevant literature on the Mediterranean Sea. The calculated ratios of (238)U-(232)Th and (40)K-(232)Th verified the lack of TENORM contribution in the Saronikos Gulf. Finally, a rough estimation was attempted concerning the residence times of fresh water inputs from a treatment plant of domestic wastes (Waste Water Treatment Plant of Psitalia) showing that fresh waters need a maximum of 15.7±7.6 d to be mixed with the open sea water.