Science.gov

Sample records for americium isotopes

  1. The Most Useful Actinide Isotope: Americium-241.

    ERIC Educational Resources Information Center

    Navratil, James D.; And Others

    1990-01-01

    Reviewed is the discovery, nuclear and chemical properties, and uses of an isotope of Americium (Am-241). Production and separation techniques used in industry are emphasized. Processes are illustrated in flow sheets. (CW)

  2. The Most Useful Actinide Isotope: Americium-241.

    ERIC Educational Resources Information Center

    Navratil, James D.; And Others

    1990-01-01

    Reviewed is the discovery, nuclear and chemical properties, and uses of an isotope of Americium (Am-241). Production and separation techniques used in industry are emphasized. Processes are illustrated in flow sheets. (CW)

  3. Updated Evaluations for Americium Isotopes

    SciTech Connect

    Brown, D A; Pruet, J

    2005-09-22

    Here we describe evaluations for Am isotopes that will be included in the next release of ENDL. Current ENDL99 evaluations for these isotopes are quite outdated and almost entirely undocumented. Because Am is important for several DNT applications, and because quality evaluations are either readily available or easily calculated, the effort to update ENDL seems warranted. Results from good existing evaluations are adopted whenever possible. To this end we devote the next section of this report to a consideration of the availability of evaluations The quality of different evaluations as well as comparisons against experiments are also presented and used to motivate our choice of adopted data sets. Plans for modifying and improving adopted evaluations are also discussed. For {sup 240}Am there are no existing evaluations. To fill this gap, we are providing a new Am evaluation based on calculations with the statistical model reaction codes TALYS and EMPIRE. This evaluation is described below. The ENDF/B-VI formatted file containing this evaluation is given in the appendix.

  4. Americium

    SciTech Connect

    Smith, James L

    2012-06-01

    The element americium marks the end of interesting behavior in the periodic table. I will talk about how this was predicted by Johansson and Rosengren and demonstrated by me. I will talk about other questions of localization.

  5. Americium

    NASA Astrophysics Data System (ADS)

    Runde, Wolfgang H.; Schulz, Wallace W.

    Americium, element 95, was discovered in 1944-45 by Seaborg et al. (1950) at the Metallurgical Laboratory of the University of Chicago as a product of the irradiation of plutonium with neutrons: 239{Pu}( n,γ )^{240} Put( n,γ )^{241} Pu → - β ^-}^{241}{Am} This reaction is still the best method for the production of pure 241Am. In post-World War II work at the University of Chicago, Cunningham isolated Am(OH)3 and measured the first absorption spectrum of the Am3+ aquo ion (Cunningham, 1948). By the 1950s, the major center for americium chemistry research in the world was at Los Alamos. Since the 1970s, the majority of publications on americium have come from researchers in the former USSR and West Germany. Extensive reviews of americium chemistry can be found in Freeman and Keller (1985), Gmelin (1979), Penneman and Asprey (1955), and Schulz (1976).

  6. Americium-241: the most useful isotope of the actinide elements

    SciTech Connect

    Navratil, J.D.

    1984-01-01

    Used extensively in nuclear gauges and in many other areas, this man-made element (Atomic Number 95) was first isolated in weighable amounts during World War II. Americium is now a very useful by-product of the nuclear industry and is produced in kilogram amounts by appropriate recovery, separation and purification processes. A review will be presented of its discovery, nuclear and chemical properties, and uses, with emphasis on its production process and separations chemistry.

  7. Isotopic ratio correlation for the isotopic composition analysis of plutonium in Am-Pu mixed samples having high americium content.

    PubMed

    Patra, Sabyasachi; Agarwal, Chhavi; Chaudhury, Sanhita; Newton Nathaniel, T; Gathibandhe, M; Goswami, A

    2013-08-01

    Interference of high amount of americium in the plutonium isotopic composition analysis has been studied by simulating gamma-ray spectra for Am-Pu samples over a wide composition range (5-97% (241)Am) for both power and research reactor grade plutonium. An alternate way for isotopic composition analysis has been proposed by correlating the isotopic ratios available in our old database with the experimentally obtained (241)Pu/(239)Pu isotopic ratio. The proposed method has been validated using simulated spectra of known isotopic compositions.

  8. EPA Method: Rapid Radiochemical Method for Americium-241, Radium-226, Plutonium-238/-239, Radiostronium, and Isotopic Uranium in Water for Environmental Restoration Following Homeland Security Events

    EPA Pesticide Factsheets

    SAM lists this method for the qualitative determination of Americium-241, Radium-226, Plutonium-238, Plutonium-239 and isotopic uranium in drinking water samples using alpha spectrometry and radiostrontium using beta counting.

  9. Isotopic and elemental composition of plutonium/americium oxides influence pulmonary and extra-pulmonary distribution after inhalation in rats.

    PubMed

    Van der Meeren, A; Grémy, O

    2010-09-01

    The biodistribution of plutonium and americium has been studied in a rat model after inhalation of two PuO(2) powders in lungs and extra-pulmonary organs from 3 d to 3 mo. The main difference between the two powders was the content of americium (approximately 46% and 4.5% of total alpha activity). The PuO(2) with a higher proportion of americium shows an accelerated transfer of activity from lungs to blood as compared to PuO(2) with the lower americium content, illustrated by increased urinary excretion and higher bone and liver actinide retention. The total alpha activity measured reflects mostly the americium biological behavior. The activity contained in epithelial lining fluid, recovered in the acellular phase of broncho-alveolar lavages, mainly contains americium, whereas plutonium remains trapped in macrophages. Epithelial lining fluid could represent a transitional pulmonary compartment prior to translocation of actinides to the blood and subsequent deposition in extra-pulmonary retention organs. In addition, differential behaviors of plutonium and americium are also observed between the PuO(2) powders with a higher dissolution rate for both plutonium and americium being obtained for the PuO(2) with the highest americium content. Our results indicate that the biological behavior of plutonium and americium after translocation into blood differ two-fold: (1) for the two actinides for the same PuO(2) aerosol, and (2) for the same actinide from the two different aerosols. These results highlight the importance of considering the specific behavior of each contaminant after accidental pulmonary intake when assessing extra-pulmonary deposits from the level of activity excreted in urine or for therapeutic strategy decisions.

  10. Sequential isotopic determination of plutonium, thorium, americium, strontium and uranium in environmental and bioassay samples.

    PubMed

    Wang, Jeng-Jong; Chen, Ing-Jane; Chiu, Jih-Hung

    2004-01-01

    A procedure has been developed to provide sequential analysis of 238Pu, 230Th, 241Am, 238U, and 90Sr in environmental and bioassay samples. Tracers and/or carriers (242Pu, 243Am, 232U, and stable strontium) are added into the sample as chemical yield monitors, and then, plutonium, thorium, strontium, americium, and uranium are sequentially separated and purified by Dowex ion-exchange resin, EiChroM Sr-resin, EiChroM TRU-resin, and Chelate-100 resin, respectively. The radioactivities of 90Sr and the actinides are measured using the liquid scintillation counter and alpha-particle spectrometer, respectively. Acidified water, glass-fiber air filter, soil, synthetic urine and synthetic feces samples of US National Institute of Standard and Technology Radiochemical Intercomparison Program(NRIP) were analyzed to verify this method. All the analytical results of 238Pu, 230Th, 90Sr, 241Am and 238U meet the traceability limit per ANSI N42.22, and when appropriate, evaluation of radiobioassay measurement bias and precision per ANSI N13.30.

  11. Aqueous Chloride Operations Overview: Plutonium and Americium Purification/Recovery

    SciTech Connect

    Kimball, David Bryan; Skidmore, Bradley Evan

    2016-06-22

    Acqueous Chloride mission is to recover plutonium and americium from pyrochemical residues (undesirable form for utilization and storage) and generate plutonium oxide and americium oxide. Plutonium oxide is recycled into Pu metal production flowsheet. It is suitable for storage. Americium oxide is a valuable product, sold through the DOE-OS isotope sales program.

  12. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    SciTech Connect

    Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Couture, A.; Haight, R. C.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Stoyer, M. A.; Wu, C. Y.; Becker, J. A.; Haslett, R. J.; Henderson, R. A.

    2009-01-28

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented where the fission events were actively triggered during the experiments. In these experiments, a Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) events from (n,f) events. The first direct observation of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  13. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    SciTech Connect

    Jandel, Marian

    2008-01-01

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) from (n,f) events. The first evidence of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  14. MODELING AND FISSION CROSS SECTIONS FOR AMERICIUM.

    SciTech Connect

    ROCHMAN, D.; HERMAN, M.; OBLOZINSKY, P.

    2005-05-01

    This is the final report of the work performed under the LANL contract on the modeling and fission cross section for americium isotopes (May 2004-June 2005). The purpose of the contract was to provide fission cross sections for americium isotopes with the nuclear reaction model code EMPIRE 2.19. The following work was performed: (1) Fission calculations capability suitable for americium was implemented to the EMPIRE-2.19 code. (2) Calculations of neutron-induced fission cross sections for {sup 239}Am to {sup 244g}Am were performed with EMPIRE-2.19 for energies up to 20 MeV. For the neutron-induced reaction of {sup 240}Am, fission cross sections were predicted and uncertainties were assessed. (3) Set of fission barrier heights for each americium isotopes was chosen so that the new calculations fit the experimental data and follow the systematics found in the literature.

  15. RECOVERY OF AMERICIUM

    DOEpatents

    Ader, M.; Hyman, H.H.

    1960-04-26

    A process is given for separating americium and plutonium and recovering the americium. Plutonium is extracted from a solution containing plutonium and americium with a water-insoluble solvent, and americium is precipitated from the aqueous phase by adding a ferric salt and an alkali metal hydroxide thereto. The precipitate may then be dissolved in hydrochloric acid and the ferric salt extracted from the americium with an organlc solvent.

  16. Determination of Atto- to Femtogram Levels of Americium and Curium Isotopes in Large-Volume Urine Samples by Compact Accelerator Mass Spectrometry.

    PubMed

    Dai, Xiongxin; Christl, Marcus; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2016-03-01

    Ultralow level analysis of actinides in urine samples may be required for dose assessment in the event of internal exposures to these radionuclides at nuclear facilities and nuclear power plants. A new bioassay method for analysis of sub-femtogram levels of Am and Cm in large-volume urine samples was developed. Americium and curium were co-precipitated with hydrous titanium oxide from the urine matrix and purified by column chromatography separation. After target preparation using mixed titanium/iron oxides, the final sample was measured by compact accelerator mass spectrometry. Urine samples spiked with known quantities of Am and Cm isotopes in the range of attogram to femtogram levels were measured for method evaluation. The results are in good agreement with the expected values, demonstrating the feasibility of compact accelerator mass spectrometry (AMS) for the determination of minor actinides at the levels of attogram/liter in urine samples to meet stringent sensitivity requirements for internal dosimetry assessment.

  17. Neutron production in several americium compounds

    SciTech Connect

    Shores, E. F.

    2004-01-01

    Americium, like other alpha emitting actinides, may indirectly produce neutrons when combined with light target materials. These (alpha,n) reaction neutrons, along with well known photon lines, have been an advantage of the {sup 241}Am isotope for diverse applications such as radiography, thickness gauges, neutron sources, and even common household smoke detectors. To characterize these sources, the SOURCES code was used to calculate neutron yields and spectra from {sup 241}Am metal, americium oxide, and americium aluminum alloys. Such information may be used as source terms for future transport problems (e.g. shielding calculations). Table 1 contains neutron yields for six americium configurations. The metal, oxides, and alloys were run as homogeneous problems while the interface case was run in both two- and three-region interface modes.

  18. Investigation of factors affecting the quality of americium electroplating.

    PubMed

    Trdin, M; Benedik, L; Samardžija, Z; Pihlar, B

    2012-09-01

    Four different electrolyte solutions were used in the electrodeposition of americium and their influences on the quality of the thin layer of deposited americium isotopes in combination with three different cathode disc materials were investigated. The relations between alpha spectral resolution and disc surface properties were established.

  19. Assessment of the global fallout of plutonium isotopes and americium-241 in the soil of the central region of Saudi Arabia.

    PubMed

    Shabana, E I; Al-Shammari, H L

    2001-01-01

    A radiochemical technique for determination of plutonium isotopes and 241Am in soil samples is tested against IAEA-standard reference materials to determine its accuracy and precision for reliable results. The technique is then used in the investigation of topsoil samples, collected from the natural environment of the central region of Saudi Arabia, to assess the effect of fallout accumulation of these radionuclides in the region. Plutonium and americium were sequentially separated from all other components of the sample by anion-exchange chromatography and co-precipitated with Nd3+ as fluorides. The precipitates were mounted on membrane filters and measured using a high-resolution alpha-spectrometer. The results of the analysis of the reference materials showed satisfactory sensitivity and precision of the technique. The results of the analyzed soil samples show activity levels ranging from < LLD to 0.089 and from

  20. New Fecal Method for Plutonium and Americium

    SciTech Connect

    Maxwell, S.L. III

    2000-06-27

    A new fecal analysis method that dissolves plutonium oxide was developed at the Westinghouse Savannah River Site. Diphonix Resin (Eichrom Industries), is used to pre-concentrate the actinides from digested fecal samples. A rapid microwave digestion technique is used to remove the actinides from the Diphonix Resin, which effectively extracts plutonium and americium from acidic solutions containing hydrofluoric acid. After resin digestion, the plutonium and americium are recovered in a small volume of nitric acid that is loaded onto small extraction chromatography columns, TEVA Resin and TRU Resin (Eichrom Industries). The method enables complete dissolution of plutonium oxide and provides high recovery of plutonium and americium with good removal of thorium isotopes such as thorium-228.

  1. Americium recovery from reduction residues

    DOEpatents

    Conner, W.V.; Proctor, S.G.

    1973-12-25

    A process for separation and recovery of americium values from container or bomb'' reduction residues comprising dissolving the residues in a suitable acid, adjusting the hydrogen ion concentration to a desired level by adding a base, precipitating the americium as americium oxalate by adding oxalic acid, digesting the solution, separating the precipitate, and thereafter calcining the americium oxalate precipitate to form americium oxide. (Official Gazette)

  2. Vacuum distillation of americium metal

    SciTech Connect

    Berry, J W; Knighton, J B; Nannie, C A

    1982-01-22

    High-purity americium metal has been distilled in multigram quantities from a plutonium-americium alloy. The procedure consisted of a two-stage vacuum distillation carried out at 1200/sup 0/C and 10/sup -6/ torr pressure. Four batches of americium metal were produced ranging in weight from 13.3 grams to 54.1 grams. The purity of the americium product ranged from 99.27 to 99.79%.

  3. Radionuclide Basics: Americium-241

    EPA Pesticide Factsheets

    Americium (chemical symbol Am) is a man-made radioactive metal that is solid under normal conditions. Exposure to a significant amount of Am-241 is generally unlikely. Small amounts are found in the soil, plants and water from nuclear weapons testing.

  4. SEPARATION OF AMERICIUM FROM PROMETHIUM

    DOEpatents

    Pressly, R.E.

    1959-07-01

    Promethium-147 is separated from americium in acidic aqueous solution by adding fluosilicic acid to the solution, heating the solution to form a promethium precipitate and separating the precipitate from solution. The precipitate is then re-dissolved by ihe addition of boric acid and nitric acid, and re-precipitated by the addition of fluosilicic acid. This procedure is repeated six or more times to obtain a relatively americium-free promeihium precipitate. Americium may be separately recovered from the supernatant liquids. This process is applicable to the recovery of promethium from fission-product solutions which have been allowed to decay for a period of two to four years.

  5. SEPARATION OF CURIUM AND AMERICIUM

    DOEpatents

    Fields, P.R.; Isaac, N.M.

    1962-02-20

    Curium and americium are contained in an anhydrous molten salt medium having a low melting point. Curium is preferentially extracted from the molten salt by a hot organic solvent containing preferably less than 10% alkyl phosphate. (AEC)

  6. Plutonium and americium separation from salts

    DOEpatents

    Hagan, Paul G.; Miner, Frend J.

    1976-01-01

    Salts or materials containing plutonium and americium are dissolved in hydrochloric acid, heated, and contacted with an alkali metal carbonate solution to precipitate plutonium and americium carbonates which are thereafter readily separable from the solution.

  7. [Rapid analysis of the radionuclides plutonium and americium-241 in soils].

    PubMed

    Egorov, A V; Klochkova, N V

    2009-01-01

    The paper shows it possible to perform a rapid analysis of the isotopes of plutomium and americium-241. The basis of the developed rapid analysis is X-spectrometric determination of the amount of plutonium isotopes and gamma-spectrometric determination of the radionuclide 241AM.

  8. Phonon dynamics of americium telluride

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Ahirwar, Ashok K.; Sanyal, S. P.

    2013-06-01

    We report for the first time the complete phonon dispersion curves for Americium telluride (AmTe) using a breathing shell models (BSM) to establish their predominant ionic nature. The results obtained in the present study show the general features of the phonon spectrum. We could not compare our results with the experimental measurements as they are not available so far. We emphasize the need of neutron scattering measurements to compare our results. We also report, for the first time specific heat for this compound.

  9. Americium/Curium Vitrification Pilot Tests - Part II

    SciTech Connect

    Marra, J.E.; Baich, M.A.; Fellinger, A.P.; Hardy, B.J.; Herman, D.T.; Jones, T.M.; Miller, C.B.; Miller, D.H.; Snyder, T. K.; Stone, M.E.

    1998-05-01

    Isotopes of americium (Am) and curium (Cm) were produced in the past at the Savannah River Site (SRS) for research, medical, and radiological applications. These highly radioactive and valuable isotopes have been stored in an SRS reprocessing facility for a number of years. Vitrification of this solution will allow the material to be more safely stored until it is transported to the DOE Oak Ridge Reservation for use in research and medical applications. A previous paper described operation results from the Am-Cm Melter 2A pilot system, a full-scale non-radioactive pilot facility. This paper presents the results from continued testing in the Pilot Facility and also describes efforts taken to look at alternative vitrification process operations and flowsheets designed to address the problems observed during melter 2A pilot testing.

  10. Treatment of accidental intakes of plutonium and americium: guidance notes.

    PubMed

    Ménétrier, F; Grappin, L; Raynaud, P; Courtay, C; Wood, R; Joussineau, S; List, V; Stradling, G N; Taylor, D M; Bérard, Ph; Morcillo, M A; Rencova, J

    2005-06-01

    The scientific basis for the treatment of the contamination of the human body by plutonium, americium and other actinides is reviewed. Guidance Notes are presented for the assistance of physicians and others who may be called upon to treat workers or members of the public who may become contaminated internally with inhaled plutonium nitrate, plutonium tributyl phosphate, americium nitrate or americium oxide.

  11. Americium binding to humic acid.

    PubMed

    Peters, A J; Hamilton-Taylor, J; Tipping, E

    2001-09-01

    The binding of americium (Am) by peat humic acid (PHA) has been investigated at Am concentrations between 10(-1) and 10(-7) M at pH approximately 2.6 in the presence and absence of Cu as a competing ion. Cu-PHA binding was also investigated in order to derive independent binding constants for use in modeling the competitive binding studies. Humic ion-binding model VI was used to compare the acquired data with previously published binding data and to investigate the importance of high-affinity binding sites in metal-PHA binding. Am was not observed to bind to high-affinity, low-concentration binding sites. The model VI parameter deltaLK2 takes into accountthe small number of strong sites in PHA and was found to be important for Cu-PHA binding but not for Am-PHA binding, regardless of whether Cu was present. Analysis of the PHA sample revealed that it contained a considerable quantity of Fe not removed by the extraction procedure, much of which is believed to be present as Fe(III). Model VI was then used to investigate the possible importance of the presence of Fe(III) in the Am-PHA binding experiments. When Fe(III) was assumed to be present, improved descriptions of the data by model VI were obtained by assuming that all of the metals [Am, Cu, and Fe(III)] undergo strong binding. This highlights the importance of Fe(III) competition in metal-PHA binding studies and possible shortcomings in the extraction procedure used to extract PHA.

  12. Pretreatment of americium/curium solutions for vitrification

    SciTech Connect

    Rudisill, T.S.

    1996-03-18

    Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to the heavy isotope programs at Oak Ridge National Laboratory. Prior to vitrification, an in-tank oxalate precipitation and a series of oxalic/nitric acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Pretreatment development experiments were performed to understand the behavior of the lanthanides and the metal impurities during the oxalate precipitation and properties of the precipitate slurry. The results of these experiments will be used to refine the target glass composition allowing optimization of the primary processing parameters and design of the solution transfer equipment.

  13. Solubility of Plutonium (IV) Oxalate During Americium/Curium Pretreatment

    SciTech Connect

    Rudisill, T.S.

    1999-08-11

    Approximately 15,000 L of solution containing isotopes of americium and curium (Am/Cm) will undergo stabilization by vitrification at the Savannah River Site (SRS). Prior to vitrification, an in-tank pretreatment will be used to remove metal impurities from the solution using an oxalate precipitation process. Material balance calculations for this process, based on solubility data in pure nitric acid, predict approximately 80 percent of the plutonium in the solution will be lost to waste. Due to the uncertainty associated with the plutonium losses during processing, solubility experiments were performed to measure the recovery of plutonium during pretreatment and a subsequent precipitation process to prepare a slurry feed for a batch melter. A good estimate of the plutonium content of the glass is required for planning the shipment of the vitrified Am/Cm product to Oak Ridge National Laboratory (ORNL).The plutonium solubility in the oxalate precipitation supernate during pretreatment was 10 mg/mL at 35 degrees C. In two subsequent washes with a 0.25M oxalic acid/0.5M nitric acid solution, the solubility dropped to less than 5 mg/mL. During the precipitation and washing steps, lanthanide fission products in the solution were mostly insoluble. Uranium, and alkali, alkaline earth, and transition metal impurities were soluble as expected. An elemental material balance for plutonium showed that greater than 94 percent of the plutonium was recovered in the dissolved precipitate. The recovery of the lanthanide elements was generally 94 percent or higher except for the more soluble lanthanum. The recovery of soluble metal impurities from the precipitate slurry ranged from 15 to 22 percent. Theoretically, 16 percent of the soluble oxalates should have been present in the dissolved slurry based on the dilution effects and volumes of supernate and wash solutions removed. A trace level material balance showed greater than 97 percent recovery of americium-241 (from the beta dec

  14. Integration of Americium Heat Source into the Advanced Stirling Radioisotope Generator

    NASA Astrophysics Data System (ADS)

    Schulze, Erich; Quinn, Richard

    2014-08-01

    The Lockheed Martin developed Advanced Stirling Radioisotope Generator (ASRG) design uses similar technology as proposed for the European Space Agency (ESA) Radioisotope Power System (RPS) development program but different isotopes. The RPS uses americium, 241Am isotope, while the ASRG uses plutonium, 238Pu isotope. The 238Pu isotope provides four times greater thermal output per kilogram than the 241Am isotope. Lockheed Martin performed an internally funded feasibility assessment that determined integration of a 241Am fueled heat source into the ASRG is achievable with no changes to ASRG technology and only structural and volumetric design considerations required. Lockheed Martin is interested in developing collaborative partnerships with the United Kingdom (UK) for the ESA RPS development program.

  15. Americium/Curium Melter 2A Pilot Tests

    SciTech Connect

    Smith, M.E.; Fellinger, A.P.; Jones, T.M.; Miller, C.B.; Miller, D.H.; Snyder, T.K.; Stone, M.E.; Witt, D.C.

    1998-05-01

    Isotopes of americium (Am) and curium (Cm) were produced in the past at the Savannah River Site (SRS) for research, medical, and radiological applications. These highly radioactive and valuable isotopes have been stored in an SRS reprocessing facility for a number of years. Vitrification of this solution will allow the material to be more safely stored until it is transported to the DOE Oak Ridge Reservation for use in research and medical applications. To this end, the Am/Cm Melter 2A pilot system, a full-scale non- radioactive pilot plant of the system to be installed at the reprocessing facility, was designed, constructed and tested. The full- scale pilot system has a frit and aqueous feed delivery system, a dual zone bushing melter, and an off-gas treatment system. The main items which were tested included the dual zone bushing melter, the drain tube with dual heating and cooling zones, glass compositions, and the off-gas system which used for the first time a film cooler/lower melter plenum. Most of the process and equipment were proven to function properly, but several problems were found which will need further work. A system description and a discussion of test results will be given.

  16. Americium/curium extraction from a lanthanide borosilicate glass

    SciTech Connect

    Rudisill, T.S.; Pareizs, J.M.; Ramsey, W.G.

    1996-12-01

    A solution containing kilogram quantities of highly radioactive isotopes of americium and curium (Am/Cm) and lanthanide fission products is currently stored in a process tank at the Department of Energy`s Savannah River Site (SRS). This tank and its vital support systems are old, subject to deterioration, and prone to possible leakage. For this reason, a program has been initiated to stabilize this material as a lanthanide borosilicate (LBS) glass. The Am/Cm has commercial value and is desired for use by the heavy isotope programs at the Oak Ridge National Laboratory (ORNL). A recovery flowsheet was demonstrated using a curium containing glass to extract the Am/Cm from the glass matrix. The procedure involved grinding the glass to less than 200 mesh and dissolving in concentrated nitric acid at 110 {degrees}C. Under these conditions, the dissolution was essentially 100% after 2 hours except for the insoluble silicon. Using a nonradioactive surrogate, the expected glass dissolution rate during Am/Cm recovery was bracketed by using both static and agitated conditions. The measured rates, 0.0082 and 0.040 g/hr.sq cm, were used to develop a predictive model for the time required to dissolve a spherical glass particle in terms of the glass density, particle size, and measured rate. The calculated dissolution time was in agreement with the experimental observation that the curium glass dissolution was complete in less than 2 hrs.

  17. Portable, high intensity isotopic neutron source provides increased experimental accuracy

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Stewart, D. C.; Wahlgren, M. A.

    1968-01-01

    Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy.

  18. Final Radiological Assessment of External Exposure for CLEAR-Line Americium Recovery Operations

    SciTech Connect

    Davis, Adam C.; Belooussova, Olga N.; Hetrick, Lucas Duane

    2014-11-12

    Los Alamos National Laboratory is currently planning to implement an americium recovery program. The americium, ordinarily isotopically pure 241Am, would be extracted from existing Pu materials, converted to an oxide and shipped to support fabrication of americium oxide-beryllium neutron sources. These operations would occur in the currently proposed Chloride Extraction and Actinide Recovery (CLEAR) line of glove boxes. This glove box line would be collocated with the currently-operational Experimental Chloride Extraction Line (EXCEL). The focus of this document is to provide an in-depth assessment of the currently planned radiation protection measures and to determine whether or not further design work is required to satisfy design-goal and ALARA requirements. Further, this document presents a history of americium recovery operations in the Department of Energy and high-level descriptions of the CLEAR line operations to provide a basis of comparison. Under the working assumptions adopted by this study, it was found that the evaluated design appears to mitigate doses to a level that satisfies the ALARA-in-design requirements of 10 CFR 835 as implemented by the Los Alamos National Laboratory procedure P121. The analyses indicate that extremity doses would also meet design requirements. Dose-rate calculations were performed using the radiation transport code MCNP5 and doses were estimated using a time-motion study developed in consort with the subject matter expert. A copy of this report and all supporting documentation are located on the Radiological Engineering server at Y:\\Rad Engineering\\2013 PROJECTS\\TA-55 Clear Line.

  19. Evaluation of several electrolyte mixture-cathode material combinations in electrodeposition of americium radioisotopes for alpha-spectrometric measurements.

    PubMed

    Krmpotić, Matea; Rožmarić, Martina; Benedik, Ljudmila

    2017-10-01

    Three different types of electrolytes, subsequently modified and adjusted, in combination with three cathode materials used as source backings were analysed for electrodeposition of americium isotopes for alpha-spectrometric measurements. The obtained results are discussed in terms of electrodeposition yield and source quality (source homogeneity and spectral resolution, FWHM). The optimal conditions for source preparation are provided. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Surface complexation modeling of americium sorption onto volcanic tuff.

    PubMed

    Ding, M; Kelkar, S; Meijer, A

    2014-10-01

    Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways. Published by Elsevier Ltd.

  1. Removal of plutonium and americium from alkaline waste solutions

    DOEpatents

    Schulz, Wallace W.

    1979-01-01

    High salt content, alkaline waste solutions containing plutonium and americium are contacted with a sodium titanate compound to effect removal of the plutonium and americium from the alkaline waste solution onto the sodium titanate and provide an effluent having a radiation level of less than 10 nCi per gram alpha emitters.

  2. Electron heat capacity and lattice properties of Americium

    NASA Astrophysics Data System (ADS)

    Povzner, A. A.; Filanovich, A. N.; Os'kina, V. A.; Volkov, A. G.

    2013-12-01

    The temperature dependence of the electron heat capacity of americium is calculated using the concepts on the electronic structure and magnetic properties of this element. The Debye temperature, the thermal expansion coefficient, and the bulk modulus of americium are determined on the basis of the results of calculations and experimental data on heat capacity.

  3. Rapid Radiochemical Method for Americium-241 in Building ...

    EPA Pesticide Factsheets

    Technical Fact Sheet Analysis Purpose: Qualitative analysis Technique: Alpha spectrometry Method Developed for: Americium-241 in building materials Method Selected for: SAM lists this method for qualitative analysis of americium-241 in concrete or brick building materials. Summary of subject analytical method which will be posted to the SAM website to allow access to the method.

  4. Delayed-fission properties of neutron-deficient americium nuclei

    SciTech Connect

    Hall, H.L. . Dept. of Chemistry)

    1989-10-23

    Characteristics of the delayed-fission decay mode in light americium nuclei have been investigated. Measurements on the unknown isotopes {sup 230}Am and {sup 236}Am were attempted, and upper limits on the delayed-fission branches of these nuclei were determined. Evidence of the existence of {sup 236}Am was observed in radiochemical separations. Total kinetic energy and mass-yield distributions of the electron-capture delayed-fission mode were measured for {sup 232}Am (t{sub 1/2} = 1.31 {plus minus} 0.04 min) and for {sup 234}Am (t{sub 1/2} = 2.32 {plus minus} 0.08 min), and delayed-fission probabilities of 6.9 {times} 10{sup {minus}4} and 6.6 {times} 10{sup {minus}5}, respectively, were determined. The total kinetic energy and the asymmetric mass-yield distributions are typical of fission of mid-range actinides. No discernible influence of the anomalous triple-peaked mass division characteristic of the thorium-radium region was detected. Measurements of the time correlation between the electron-capture x-rays and the subsequent fission conform that the observed fissions arise from the electron-capture delayed-fission mechanism. Delayed fission has provided a unique opportunity to extend the range of low-energy fission studies to previously inaccessible regions. 71 refs., 44 figs., 13 tabs.

  5. Density of simulated americium/curium melter feed solution

    SciTech Connect

    Rudisill, T.S.

    1997-09-22

    Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to Oak Ridge National Laboratory and use in heavy isotope production programs. Prior to vitrification, a series of in-tank oxalate precipitation and nitric/oxalic acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Following nitric acid dissolution and oxalate destruction, the solution will be denitrated and evaporated to a dissolved solids concentration of approximately 100 g/l (on an oxide basis). During the Am/Cm vitrification, an airlift will be used to supply the concentrated feed solution to a constant head tank which drains through a filter and an in-line orifice to the melter. Since the delivery system is sensitive to the physical properties of the feed, a simulated solution was prepared and used to measure the density as a function of temperature between 20 to 70{degrees} C. The measured density decreased linearly at a rate of 0.0007 g/cm3/{degree} C from an average value of 1.2326 g/cm{sup 3} at 20{degrees} C to an average value of 1.1973g/cm{sup 3} at 70{degrees} C.

  6. Americium/curium bushing melter drain tests

    SciTech Connect

    Smith, M.E.; Hardy, B.J.; Smith, M.E.

    1997-07-01

    Americium and curium were produced in the past at the Savannah River Site (SRS) for research, medical, and radiological applications. They have been stored in a nitric acid solution in an SRS reprocessing facility for a number of years. Vitrification of the americium/curium (Am/Cm) solution will allow the material to be safely stored or transported to the DOE Oak Ridge Reservation. Oak Ridge is responsible for marketing radionuclides for research and medical applications. The bushing melter technology being used in the Am/Cm vitrification research work is also under consideration for the stabilization of other actinides such as neptunium and plutonium. A series of melter drain tests were conducted at the Savannah River Technology Center to determine the relationship between the drain tube assembly operating variables and the resulting pour initiation times, glass flowrates, drain tube temperatures, and stop pour times. Performance criteria such as ability to start and stop pours in a controlled manner were also evaluated. The tests were also intended to provide support of oil modeling of drain tube performance predictions and thermal modeling of the drain tube and drain tube heater assembly. These drain tests were instrumental in the design of subsequent melter drain tube and drain tube heaters for the Am/Cm bushing melter, and therefore in the success of the Am/Cm vitrification and plutonium immobilization programs.

  7. Self-irradiation and oxidation effects on americium sesquioxide and Raman spectroscopy studies of americium oxides

    SciTech Connect

    Horlait, Denis; Delahaye, Thibaud

    2014-09-15

    Americium oxides samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, with an emphasis on their structural behavior under oxidation and self-irradiation. Raman spectra of americium dioxide (AmO{sub 2}) and sesquioxide (Am{sub 2}O{sub 3}) were obtained for the first time. With the help of literature data on isostructural oxides, Raman signatures of Ia-3 C-type Am{sub 2}O{sub 3} and P-3m1 A-type Am{sub 2}O{sub 3} are identified. For AmO{sub 2,} a clear band is noted at 390 cm{sup −1}. Its nature is compared to that of the other actinide dioxides. Am{sub 2}O{sub 3} evolution under ambient conditions and against {sup 241}Am α self-irradiation was monitored by powder XRD. The sample, initially composed of A-type Am{sub 2}O{sub 3} as major phase as well as C2/m B-type and C-type structures as minor phases, progressively oxidizes to Fm-3m AmO{sub 2−δ} over a few months. On the basis of diffractogram refinements, evolutions of unit cell volumes caused by self-irradiation are also determined and discussed. - Graphical abstract: The evolution of americium oxide under ambient conditions was monitored using XRD (X-ray diffraction) and Raman spectroscopy. After a thermal treatment under reducing conditions, a polyphasic sample mainly composed of A- and C-type americium sesquioxides is evidenced by XRD and Raman spectroscopy. The sample then evolves through two processes: oxidation and self-irradiation. The first one provokes the progressive appearance of F-type americium dioxide while the initial phases disappear, whereas the main effect of the second is a structural swelling with time. - Highlights: • The first Raman spectroscopy measurements on americium oxides were performed. • Observed Am{sub 2}O{sub 3} Raman bands were identified thanks to data on analogue compounds. • AmO{sub 2} assumed T{sub 2g} band presents a shift compared to the actinide dioxide series. • Am{sub 2}O{sub 3} evolution under self-irradiation and oxidation was also

  8. Americium/curium extraction from a lanthanide borosilciate glass

    SciTech Connect

    Rudisill, T.S.; Pareizs, J.M.; Ramsey, W.G.

    1996-12-31

    A solution containing kilogram quantities of highly radioactive isotopes of americium and curium (Am/Cm) and lanthanide fission products is currently stored in a process tank at the Department of Energy`s Savannah River Site (SRS). This tank and its vital support systems are old, subject to deterioration, and prone to possible leakage. For this reason, a program has been initiated to immobilize this material as a lanthanide borosilicate glass for safe long-term storage. The Am/Cm has commercial value and is desired for use by the heavy isotope programs at the Oak Ridge National Laboratory (ORNL). Therefore, a flowsheet was demonstrated using a curium-containing glass to extract these elements from the glass matrix. The method involved grinding the glass to less than 200 mesh and dissolving in concentrated nitric acid at 110{degrees}C. Under these conditions, the dissolution was essentially 100% after 2 hours except for silicon which remained mostly insoluble. Since the actual process conditions at ORNL could not be exactly simulated, the dissolution rate of a surrogate glass was measured using static and agitated conditions to bracket the expected rate. The measured rates, 0.040 to 0.0082 grams/hour-centimeter, were constant which allowed development of a predictive model for the time required to dissolve a glass particle of spherical geometry in terms of the glass density, particle size, and experimentally measured rate. The calculated time required to dissolve an idealized curium glass particle was in agreement with the experimental observation that dissolution was complete in less than 2 hours.

  9. RAPID METHOD FOR PLUTONIUM, AMERICIUM AND CURIUM IN VERY LARGE SOIL SAMPLES

    SciTech Connect

    Maxwell, S

    2007-01-08

    The analysis of actinides in environmental soil and sediment samples is very important for environmental monitoring. There is a need to measure actinide isotopes with very low detection limits. A new, rapid actinide separation method has been developed and implemented that allows the measurement of plutonium, americium and curium isotopes in very large soil samples (100-200 g) with high chemical recoveries and effective removal of matrix interferences. This method uses stacked TEVA Resin{reg_sign}, TRU Resin{reg_sign} and DGA-Resin{reg_sign} cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu), americium (Am), and curium (Cm) using a single multistage column combined with alpha spectrometry. The method combines an acid leach step and innovative matrix removal using cerium fluoride precipitation to remove the difficult soil matrix. This method is unique in that it provides high tracer recoveries and effective removal of interferences with small extraction chromatography columns instead of large ion exchange resin columns that generate large amounts of acid waste. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized.

  10. Plutonium and Americium Geochemistry at Hanford: A Site Wide Review

    SciTech Connect

    Cantrell, Kirk J.; Felmy, Andrew R.

    2012-08-23

    This report was produced to provide a systematic review of the state-of-knowledge of plutonium and americium geochemistry at the Hanford Site. The report integrates existing knowledge of the subsurface migration behavior of plutonium and americium at the Hanford Site with available information in the scientific literature regarding the geochemistry of plutonium and americium in systems that are environmentally relevant to the Hanford Site. As a part of the report, key research needs are identified and prioritized, with the ultimate goal of developing a science-based capability to quantitatively assess risk at sites contaminated with plutonium and americium at the Hanford Site and the impact of remediation technologies and closure strategies.

  11. PROCESS FOR SEPARATING AMERICIUM AND CURIUM FROM RARE EARTH ELEMENTS

    DOEpatents

    Baybarz, R.D.; Lloyd, M.H.

    1963-02-26

    This invention relates to methods of separating americium and curium values from rare earth values. In accordance with the invention americium, curium, and rare earth values are sorbed on an anion exchange resin. A major portion of the rare earth values are selectively stripped from the resin with a concentrated aqueous solution of lithium chloride, and americium, curium, and a minor portion of rare earth values are then stripped from the resin with a dilute aqueous solution of lithium chloride. The americium and curium values are further purified by increasing the concentration of lithium chloride in the solution to at least 8 molar and selectively extracting rare earth values from the resulting solution with a monoalkylphosphoric acid. (AEC)

  12. Frontiers of Chemistry for Americium and Curium

    DOE R&D Accomplishments Database

    Keller, O. L. Jr.

    1984-01-01

    The discoveries of americium and curium were made only after Seaborg had formulated his actinide concept in order to design the chemistry needed to separate them from irradiated /sup 239/Pu targets. Their discoveries thus furnished the first clear-cut evidence that the series exists and justified Seaborg`s bold assumption that even though Th and Pa appeared to presage a following 6d series, the pattern established by the periodic table after Cs and Ba would be repeated exactly after Fr and Ra. That is to say, a new 5f element rare earth series (the actinides) would follow Ac in the same way the 4f rare earth series (the lanthanides) follows La. The consequences of the resulting half-filled 5f/sup 7/ shell at Cm were originally presented by Seaborg as a test of his hypothesis. Recent research is outlined that substantiates Seaborg`s predictions in new and definitive ways.

  13. Higher Americium Oxidation State Research Roadmap

    SciTech Connect

    Mincher, Bruce J.; Law, Jack D.; Goff, George S.; Moyer, Bruce A.; Burns, Jon D.; Lumetta, Gregg J.; Sinkov, Sergey I.; Shehee, Thomas C.; Hobbs, David T.

    2015-12-18

    The partitioning of hexavalent Am from dissolved nuclear fuel requires the ability to efficiently oxidize Am(III) to Am(VI) and to maintain that oxidation state for a length of time sufficient to perform the separation. Several oxidants have been, or are being developed. Chemical oxidants include Ag-catalyzed ozone, Ag-catalyzed peroxydisulfate, Cu(III) periodate, and sodium bismuthate. Hexavalent americium has also now successfully been prepared by electrolysis, using functionalized electrodes. So-called auto-reduction rates of Am(VI) are sufficiently slow to allow for separations. However, for separations based on solvent extraction or ion exchange using organic resins, the high valence state must be maintained under the reducing conditions of the organic phase contact, and a holding oxidant is probably necessary. Until now, only Cu(III) periodate and sodium bismuthate oxidation have been successfully combined with solvent extraction separations. Bismuthate oxidation provided the higher DAm, since it acts as its own holding oxidant, and a successful hot test using centrifugal contactors was performed. For the other oxidants, Ag-catalyzed peroxydisulfate will not oxidize americium in nitric acid concentrations above 0.3 M, and it is not being further investigated. Peroxydisulfate in the absence of Ag catalysis is being used to prepare Am(V) in ion exchange work, discussed below. Preliminary work with Ag-catalyzed ozone has been unsuccessful for extractions of Am(VI) from 6.5 M HNO3, and only one attempt at extraction, also from 6.5 M HNO3, using the electrolytic oxidation has been attempted. However, this high acid concentration was based on the highest Am extraction efficiency using the bismuthate oxidant; which is only sparingly soluble, and thus the oxidation yield is based on bismuthate solubility. Lower acid concentrations may be sufficient with alternative oxidants and work with Ag-ozone, Cu(III) and electrolysis is on-going. Two non

  14. Frontiers of chemistry for americium and curium

    SciTech Connect

    Keller, O.L. Jr.

    1984-01-01

    The discoveries of americium and curium were made only after Seaborg had formulated his actinide concept in order to design the chemistry needed to separate them from irradiated /sup 239/Pu targets. Their discoveries thus furnished the first clear-cut evidence that the series exists and justified Seaborg's bold assumption that even though Th and Pa appeared to presage a following 6d series, the pattern established by the periodic table after Cs and Ba would be repeated exactly after Fr and Ra. That is to say, a new 5f element rare earth series (the actinides) would follow Ac in the same way the 4f rare earth series (the lanthanides) follows La. The consequences of the resulting half-filled 5f/sup 7/ shell at Cm were originally presented by Seaborg as a test of his hypothesis. Recent research is outlined that substantiates Seaborg's predictions in new and definitive ways. 15 references, 4 figures.

  15. The production, recovery, properties, and applications of americium and curium

    NASA Astrophysics Data System (ADS)

    Navratil, James D.; Schulz, Wallace W.

    1993-02-01

    Nuclear reactors produce mixtures of Am-241 and Am-242, and beta decay of plutonium produces radioactively pure Am-241. Curium is a product of intense neutron exposure of Pu-239. Separation and purification processes for americium and curium include ion exchange, precipitation, and both liquid-liquid and molten-salt extraction. This article reviews the principal production, recovery, and waste treatment processes and briefly discusses the chemical properties and uses of americium and curium.

  16. Coulometric determination of americium in acetonitrile solution of phosphoric acid

    SciTech Connect

    Perevalov, S.A.; Kulyakov, Yu.M.; Lebedev, I.A.; Myasoedov, B.F.

    1986-10-20

    A procedure was developed for the coulometric determination of americium using the electrochemical couple Am(IV)-Am(III). An acetonitrile solution of 0.3-0.2 M H/sub 3/PO/sub 4/ was used as the electrolyte. Americium can be determined in the presence of large amounts of Cm, Pu, Ce, and other impurities; limit of detection approx. 10 ..mu..g.

  17. Aqueous Chloride Operations Overview: Plutonium and Americium Purification/Recovery

    SciTech Connect

    Gardner, Kyle Shelton; Kimball, David Bryan; Skidmore, Bradley Evan

    2016-09-28

    These are a set of slides intended for an information session as part of recruiting activities at Brigham Young University. It gives an overview of aqueous chloride operations, specifically on plutonium and americium purification/recovery. This presentation details the steps taken perform these processes, from plutonium size reduction, dissolution, solvent extraction, oxalate precipitation, to calcination. For americium recovery, it details the CLEAR (chloride extraction and actinide recovery) Line, oxalate precipitation and calcination.

  18. Pyrochemical investigations into recovering plutonium from americium extraction salt residues

    SciTech Connect

    Fife, K.W.; West, M.H.

    1987-05-01

    Progress into developing a pyrochemical technique for separating and recovering plutonium from spent americium extraction waste salts has concentrated on selective chemical reduction with lanthanum metal and calcium metal and on the solvent extraction of americium with calcium metal. Both techniques are effective for recovering plutonium from the waste salt, although neither appears suitable as a separation technique for recycling a plutonium stream back to mainline purification processes. 17 refs., 13 figs., 2 tabs.

  19. Tributylphosphate extraction behavior of bismuthate-oxidized americium.

    PubMed

    Mincher, Bruce J; Martin, Leigh R; Schmitt, Nicholas C

    2008-08-04

    Higher oxidation states of americium have long been known; however, options for their preparation in acidic solution are limited. The conventional choice, silver-catalyzed peroxydisulfate, is not useful at nitric acid concentrations above about 0.3 M. We investigated the use of sodium bismuthate as an oxidant for Am (3+) in acidic solution. Room-temperature oxidation produced AmO 2 (2+) quantitatively, whereas oxidation at 80 degrees C produced AmO 2 (+) quantitatively. The efficacy of the method for the production of oxidized americium was verified by fluoride precipitation and by spectroscopic absorbance measurements. We performed absorbance measurements using a conventional 1 cm cell for high americium concentrations and a 100 cm liquid waveguide capillary cell for low americium concentrations. Extinction coefficients for the absorbance of Am (3+) at 503 nm, AmO 2 (+) at 514 nm, and AmO 2 (2+) at 666 nm in 0.1 M nitric acid are reported. We also performed solvent extraction experiments with the hexavalent americium using the common actinide extraction ligand tributyl phosphate (TBP) for comparison to the other hexavalent actinides. Contact with 30% tributyl phosphate in dodecane reduced americium; it was nevertheless extracted using short contact times. The TBP extraction of AmO 2 (2+) over a range of nitric acid concentrations is shown for the first time and was found to be analogous to that of uranyl, neptunyl, and plutonyl ions.

  20. Tributylphosphate Extraction Behavior of Bismuthate-Oxidized Americium

    SciTech Connect

    Mincher; Leigh R. Martin; Nicholas C. Schmitt

    2008-08-01

    Higher oxidation states of americium have long been known; however, options for their preparation in acidic solution are limited. The conventional choice, silver-catalyzed peroxydisulfate, is not useful at nitric acid concentrations above about 0.3 M. We investigated the use of sodium bismuthate as an oxidant for Am3+ in acidic solution. Room-temperature oxidation produced AmO2 2+ quantitatively, whereas oxidation at 80 °C produced AmO2+ quantitatively. The efficacy of the method for the production of oxidized americium was verified by fluoride precipitation and by spectroscopic absorbance measurements. We performed absorbance measurements using a conventional 1 cm cell for high americium concentrations and a 100 cm liquid waveguide capillary cell for low americium concentrations. Extinction coefficients for the absorbance of Am3+ at 503 nm, AmO2+ at 514 nm, and AmO2 2+ at 666 nm in 0.1 M nitric acid are reported. We also performed solvent extraction experiments with the hexavalent americium using the common actinide extraction ligand tributyl phosphate (TBP) for comparison to the other hexavalent actinides. Contact with 30% tributyl phosphate in dodecane reduced americium; it was nevertheless extracted using short contact times. The TBP extraction of AmO2 2+ over a range of nitric acid concentrations is shown for the first time and was found to be analogous to that of uranyl, neptunyl, and plutonyl ions.

  1. An intake of americium oxide powder: implications for biokinetic models for americium.

    PubMed

    Bull, R K; Morrison, R T; Talbot, R; Roberts, G A

    2003-01-01

    A worker inhaled 241AmO2 powder. Air sampling showed low activities but a nose blow revealed 92 Bq. Results from faecal sampling and lung and whole-body monitoring indicated an intake of about 200 Bq, but urine sampling, though commencing only 1 d after intake, showed below-threshold activities (< 0.2 mBq). This conflicts with predictions based on the ICRP Publication 67 biokinetic model for americium and the ICRP Publication 66 model for the human respiratory tract, if default lung parameters are used.

  2. Covalency in Americium(III) Hexachloride

    DOE PAGES

    Cross, Justin Neil; Su, Jing; Batista, Enrigue R.; ...

    2017-06-14

    Developing a better understanding of covalency (or orbital mixing) is of fundamental importance. Covalency occupies a central role in directing chemical and physical properties for almost any given compound or material. Hence, the concept of covalency has potential to generate broad and substantial scientific advances, ranging from biological applications to condensed matter physics. Given the importance orbital mixing combined with the difficultly in measuring covalency, estimating or inferring covalency often leads to fiery debate. Consider the 60-year controversy sparked by SEABORG and COWORKERS (1954) when it was proposed that covalency from 5f-orbitals contributed to the unique behavior of americium inmore » chloride matrixes. Herein, we describe the use of ligand K-edge X-ray absorption spectroscopy (XAS) and electronic structure calculations to quantify the extent of covalent bonding in – arguably – one of the most difficult systems to study, the Am–Cl interaction within AmCl63-. We observed both 5fand 6d-orbital mixing with the Cl-3p orbitals; however, contributions from the 6d-orbitals were more substantial. Comparisons with the isoelectronic EuCl63- indicated similar bonding for the AmIII 6d- and EuIII 5d-orbitals. Meanwhile, the results confirmed SEABORG’S 1954 hypothesis that AmIII 5f-orbital covalency was more substantial than 4forbital mixing for EuIII.« less

  3. Self-irradiation and oxidation effects on americium sesquioxide and Raman spectroscopy studies of americium oxides

    NASA Astrophysics Data System (ADS)

    Horlait, Denis; Caraballo, Richard; Lebreton, Florent; Jégou, Christophe; Roussel, Pascal; Delahaye, Thibaud

    2014-09-01

    Americium oxides samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, with an emphasis on their structural behavior under oxidation and self-irradiation. Raman spectra of americium dioxide (AmO2) and sesquioxide (Am2O3) were obtained for the first time. With the help of literature data on isostructural oxides, Raman signatures of Ia-3 C-type Am2O3 and P-3m1 A-type Am2O3 are identified. For AmO2, a clear band is noted at 390 cm-1. Its nature is compared to that of the other actinide dioxides. Am2O3 evolution under ambient conditions and against 241Am α self-irradiation was monitored by powder XRD. The sample, initially composed of A-type Am2O3 as major phase as well as C2/m B-type and C-type structures as minor phases, progressively oxidizes to Fm-3m AmO2-δ over a few months. On the basis of diffractogram refinements, evolutions of unit cell volumes caused by self-irradiation are also determined and discussed.

  4. RCRA designation of discarded americium/beryllium sealed sources

    SciTech Connect

    Kirner, N.P.

    1994-09-01

    Many sealed sources containing americium and beryllium are used throughout construction, industry, and research, and will eventually require disposal. For planning purposes it is necessary to determine whether these sources, when disposed, constitute a mixed waste, i.e., a waste containing hazardous constituents regulated under the Resource Conservation and Recovery Act and radioactive constituents regulated under the Atomic Energy Act. Waste designation criteria contained in 40 CFR 261 are evaluated in detail in this report. It is determined that discarded americium/beryllium sealed sources do not contain any wastes listed in Subpart D of 40 CFR 261, nor do the discarded sources exhibit any hazardous characteristics. Therefore, it is concluded that discarded americium/beryllium sealed sources are not a mixed waste under regulations established by the US Environmental Protection Agency. Hazardous waste regulatory programs delegated to States, however, may have regulations that differ from those of the Federal government.

  5. A TRUEX-based separation of americium from the lanthanides

    SciTech Connect

    Bruce J. Mincher; Nicholas C. Schmitt; Mary E. Case

    2011-03-01

    Abstract: The inextractability of the actinide AnO2+ ions in the TRUEX process suggests the possibility of a separation of americium from the lanthanides using oxidation to Am(V). The only current method for the direct oxidation of americium to Am(V) in strongly acidic media is with sodium bismuthate. We prepared Am(V) over a wide range of nitric acid concentrations and investigated its solvent extraction behavior for comparison to europium. While a separation is achievable in principal, the presence of macro amounts of cerium competes for the sparingly soluble oxidant and the oxidant itself competes for CMPO complexation. These factors conspire to reduce the Eu/Am separation factor from ~40 using tracer solutions to ~5 for extractions from first cycle raffinate simulant solution. To separate pentavalent americium directly from the lanthanides using the TRUEX process, an alternative oxidizing agent will be necessary.

  6. Apoptosis of rat kidney cells after 241-americium administration.

    PubMed

    Labéjof, L; Berry, J P; Duchambon, P; Poncy, J L; Galle, P

    1998-01-01

    Tumors induction by americium is well known but there are no data on the biological effects of this radionucleide at subcellular level. In order to study the possible ultrastructural lesions induced by this element, a group of rats were injected with 241-Americium-citrate (9 kBq), once a week for five weeks and sacrificed 7 days after the last injection. We describe the alterations observed in the cortex kidney using cytochemical (TUNEL reaction) and histochemical (PAS staining) methods for light microscopy as well as electron microscopy techniques. Various types of lesions were detected: condensation of nuclear chromatine, fragmentation of the nuclei, swollen mitochondria, disappearance of mitochondrial crests and skrinking of the cytoplasm. This study clearly demonstrated the induction of apoptosis by americium in rat cortex kidney cells.

  7. An americium-fueled gas core nuclear rocket

    SciTech Connect

    Kammash, T.; Galbraith, D.L.; Jan, T. )

    1993-01-10

    A gas core fission reactor that utilizes americium in place of uranium is examined for potential utilization as a nuclear rocket for space propulsion. The isomer [sup 242m]Am with a half life of 141 years is obtained from an (n, [gamma]) capture reaction with [sup 241]Am, and has the highest known thermal fission cross section. We consider a 7500 MW reactor, whose propulsion characteristics with [sup 235]U have already been established, and re-examine it using americium. We find that the same performance can be achieved at a comparable fuel density, and a radial size reduction (of both core and moderator/reflector) of about 70%.

  8. Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium

    SciTech Connect

    Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.

    2009-11-01

    Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

  9. Separation and measurement of thorium, plutonium, americium, uranium and strontium in environmental matrices.

    PubMed

    Harrison, Jennifer J; Zawadzki, Atun; Chisari, Robert; Wong, Henri K Y

    2011-10-01

    A technique for the isolation of thorium (Th), plutonium (Pu), americium (Am), uranium (U) and strontium (Sr) isotopes from various environmental matrices has been adapted from a previously published method specific to water samples (Maxwell, 2006). Separation and isolation of the various elemental fractions from a single sub-sample is possible, thereby eliminating the need for multiple analyses. The technique involves sample dissolution, concentration via calcium phosphate co-precipitation, rapid column extraction using TEVA™, TRU™ and Sr-Spec™ resin cartridges, alpha spectrometry for Th, Pu, U and Am and Cerenkov counting for Sr. Various standard reference materials were analysed and chemical yields are in the range of 70-80% for Th, Am, U and Sr and 50-60% for Pu. Sample sizes of up to 10 L for water, 5 g for dry soil and sediment and 10 g for dry vegetation and seaweed can be processed using this technique. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Discovery of isotopes of the transuranium elements with 93≤Z≤98

    SciTech Connect

    Fry, C.; Thoennessen, M.

    2013-01-15

    One hundred and five isotopes of the transuranium elements neptunium, plutonium, americium, curium, berkelium, and californium have been observed so far; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  11. Discovery of isotopes of the transuranium elements with 93≤Z≤98

    NASA Astrophysics Data System (ADS)

    Fry, C.; Thoennessen, M.

    2013-01-01

    One hundred and five isotopes of the transuranium elements neptunium, plutonium, americium, curium, berkelium, and californium have been observed so far; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  12. Behavior of Americium in Simulated Wounds in Nonhuman Primates

    DOE PAGES

    Poudel, Deepesh; Guilmette, Raymond A.; Bertelli, Luiz; ...

    2017-06-01

    An americium solution injected intramuscularly into several nonhuman primates (NHPs) was found to behave differently than predicted by the wound models described in the NCRP Report 156. This was because the injection was made along with a citrate solution, which is known to be more soluble than chlorides, oxides, or nitrates on which the NCRP Report was based. We developed a multi-exponential wound model specific to the injected americium solution based on the retention in the intramuscular sites. The model was coupled with the americium systemic model to interpret the urinary excretion data and assess the intake, and it wasmore » determined that the models were adequate to predict early urinary excretion in most cases but unable to predict late urinary excretion. This was attributed to the differences in the systemic handling of americium between humans and nonhuman primates. Furthermore, information on the type of wounds, solubility, particle size, mass, chemical form, etc., should always be considered when performing wound dosimetry.« less

  13. Recovery of americium-241 from aged plutonium metal

    SciTech Connect

    Gray, L.W.; Burney, G.A.; Reilly, T.A.; Wilson, T.W.; McKibben, J.M.

    1980-12-01

    About 5 kg of ingrown /sup 241/Am was recovered from 850 kg of aged plutonium using a process developed specifically for Savannah River Plant application. The aged plutonium metal was first dissolved in sulfamic acid. Sodium nitrite was added to oxidize the plutonium to Pu(IV) and the residual sulfamate ion was oxidized to nitrogen gas and sulfate. The plutonium and americium were separated by one cycle of solvent extraction. The recovered products were subsequently purified by cation exchange chromatography, precipitated as oxalates, and calcined to the oxides. Plutonium processng was routine. Before cation exchange purification, the aqueous americium solution from solvent extraction was concentrated and stripped of nitric acid. More than 98% of the /sup 241/Am was then recovered from the cation exchange column where it was effectively decontaminated from all major impurities except nickel and chromium. This partially purified product solution was concentrated further by evaporation and then denitrated by reaction with formic acid. Individual batches of americium oxalate were then precipitated, filtered, washed, and calcined. About 98.5% of the americium was recovered. The final product purity averaged 98% /sup 241/AmO/sub 2/; residual impurities were primarily lead and nickel.

  14. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  15. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    SciTech Connect

    Grimes, Travis Shane; Mincher, Bruce Jay; Schmitt, Nicholas C

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  16. Effects of intense alpha irradiation on the behavior of americium in perchlorate solutions

    SciTech Connect

    Kornilov, A.S.; Frolov, A.A.; Vasil'ev, V.Ya.

    1987-05-01

    Studies have been made on the radiation chemistry of americium(VI) and americium(V) in solutions of perchloric acid and sodium perchlorate. The reduction rate is related to the dose rate and perchlorate concentration. The radiolysis products in perchlorate solutions are vigorous reducing agents for americium(VI). There is a correlation between the yield in the reduction of americium(VI) and the yield of radiolysis products. Prolonged storage of saturated weakly acid solutions of sodium perchlorate containing americium(III) and curium(III) causes the deposition of the actinoid hydroxides as well as sodium chlorate and chloride. The americium in the precipitate is partially oxidized to the pentavalent state.

  17. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, J.R.; Dunn, J.G.; Avens, L.R.

    1987-02-13

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF/sub 4/ is not further oxidized to AmF/sub 6/ by the application of O/sub 2/F at room temperature thereto, while plutonium compounds present in the americium sample are fluorinated to volatile PuF/sub 6/, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride thereof.

  18. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, John R.; Dunn, Jerry G.; Avens, Larry R.

    1987-01-01

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF.sub.4 is not further oxidized to AmF.sub.6 by the application of O.sub.2 F at room temperature, while plutonium compounds present in the americium sample are fluorinated to volatile PuF.sub.6, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride.

  19. Ingestion Pathway Transfer Factors for Plutonium and Americium

    SciTech Connect

    Blanchard, A.

    1999-07-28

    Overall transfer factors for major ingestion pathways are derived for plutonium and americium. These transfer factors relate the radionuclide concentration in a given foodstuff to deposition on the soil. Equations describing basic relationships consistent with Regulatory Guide 1.109 are followed. Updated values and coefficients from IAEA Technical Reports Series No. 364 are used when a available. Preference is given to using factors specific to the Savannah River Site.

  20. Americium in the beagle dog: biokinetic and dosimetric model.

    PubMed

    Luciani, A; Polig, E; Lloyd, R D; Miller, S C

    2006-05-01

    A biokinetic model of the systemic distribution of americium in the beagle dog is presented. The model is based on a previous biokinetic model of plutonium. The data sets used for the development of the model were the measurements of excreted activity (urine and feces) and organ burdens (skeleton, liver, and other soft tissues) for different levels of initial injected activity. In developing the model, the compartmental structure of the skeleton of the plutonium model was adopted, and only the numerical values of parameters were adapted. The model well describes the fractions of americium in the skeleton, liver, and soft tissues and the total fraction excreted in urine and feces. The tuning of the liver clearance parameter provides a realistic description of the change in the partitioning between liver and skeleton for different injection levels. The most significant features of the biokinetics and dosimetry of americium and plutonium in beagles are compared. The total fractions of the clearance to the skeleton and the liver are roughly equal to the value for plutonium, but the partitioning of americium between these organs is reversed with respect to the partitioning of plutonium. 241Am doses to liver and skeleton are similar to 239Pu doses, owing to some counteracting factors. For the highest injection level, the liver mass is dependent on the time post injection. For the skeletal tissues, the dose to the cortical endosteum by far exceeds the dose to the trabecular endosteum and the red marrow. The model provides the basis for statistical survival analyses and risk estimates.

  1. On the structure of thorium and americium adenosine triphosphate complexes.

    PubMed

    Mostapha, Sarah; Fontaine-Vive, Fabien; Berthon, Laurence; Boubals, Nathalie; Zorz, Nicole; Solari, Pier Lorenzo; Charbonnel, Marie Christine; Den Auwer, Christophe

    2014-11-01

    The actinides are chemical poisons and radiological hazards. One challenge to better appraise their toxicity and develop countermeasures in case of exposure of living organisms is to better assess pathways of contamination. Because of the high chemical affinity of those actinide elements for phosphate groups and the ubiquity of such chemical functions in biochemistry, nucleotides and in particular adenosine triphosphate nucleotide (ATP) may be considered critical target building blocks for actinides. Combinations of spectroscopic techniques (Fourier transformed Infra Red [FTIR], Electrospray Ionization Mass Spectrometry [ESI-MS], and Extended X-ray Absorption Fine Structure [EXAFS]) with quantum chemical calculations have been implemented in order to assess the actinides coordination arrangement with ATP. We describe and compare herein the interaction of ATP with thorium and americium; thorium(IV) as a representative of actinide(IV) like plutonium(IV) and americium(III) as a representative of all heavier actinides. In the case of thorium, an insoluble complex is readily formed. In the case of americium, a behavior identical to that described previously for lutetium has been observed with insoluble and soluble complexes. The comparative study of ATP complexation with Th(IV) and Am(III) shows their ability to form insoluble complexes for which a structural model has been proposed by analogy with previously described Lu(III) complexes.

  2. AMERICIUM SEPARATIONS FROM NITRIC ACID PROCESS EFFLUENT STREAMS

    SciTech Connect

    M. BARR; G. JARVINEN; ET AL

    2000-08-01

    The aging of the US nuclear stockpile presents a number of challenges, including the ever-increasing radioactivity of plutonium residues from {sup 241}Am. Minimization of this weak gamma-emitter in process and waste solutions is desirable to reduce both worker exposure and the effects of radiolysis on the final waste product. Removal of americium from plutonium nitric acid processing effluents, however, is complicated by the presence of large.quantities of competing metals, particularly Fe and Al, and-strongly oxidizing acidic solutions. The reprocessing operation offers several points at which americium removal maybe attempted, and we are evaluating two classes of materials targeted at different steps in the process. Extraction chromatography resin materials loaded with three different alkylcarbamoyl phosphinates and phosphine oxides were accessed for Am removal efficiency and Am/Fe selectivity from 1-7 molar nitric acid solutions. Commercial and experimental mono- and bifunctional anion-exchange resins were evaluated for total alpha-activity removal from post-evaporator solutions whose composition, relative to the original nitric acid effluent, is reduced in acid and greatly increased in total salt content. With both classes of materials, americium/total alpha emission removal is sufficient to meet regulatory requirements even under sub-optimal conditions. Batch distribution coefficients, column performance data, and the effects of Fe-masking agents will be presented.

  3. Plutonium and Americium Alpha Radiolysis of Nitric Acid Solutions.

    PubMed

    Horne, Gregory P; Gregson, Colin R; Sims, Howard E; Orr, Robin M; Taylor, Robin J; Pimblott, Simon M

    2017-02-02

    The yield of HNO2, as a function of absorbed dose and HNO3 concentration, from the α-radiolysis of aerated HNO3 solutions containing plutonium or americium has been investigated. There are significant differences in the yields measured from solutions of the two different radionuclides. For 0.1 mol dm(-3) HNO3 solutions, the radiolytic yield of HNO2 produced by americium α-decay is below the detection limit, whereas for plutonium α-decay the yield is considerably greater than that found previously for γ-radiolysis. The differences between the solutions of the two radionuclides are a consequence of redox reactions involving plutonium and the products of aqueous HNO3 radiolysis, in particular H2O2 and HNO2 and its precursors. This radiation chemical behavior is HNO3 concentration dependent with the differences between plutonium and americium α-radiolysis decreasing with increasing HNO3 concentration. This change may be interpreted as a combination of α-radiolysis direct effects and acidity influencing the plutonium oxidation state distribution, which in turn affects the radiation chemistry of the system.

  4. Search for unknown isotopes using the JAERI-ISOL

    NASA Astrophysics Data System (ADS)

    Ichikawa, S.; Tsukada, K.; Oura, Y.; Iimura, H.; Nishinaka, I.; Hatsukawa, Y.; Nagame, Y.; Asai, M.; Osa, A.; Kojima, Y.; Hirose, T.; Kawade, K.; Ohyama, T.; Sueki, K.

    1996-04-01

    A search for unknown neutron-rich rare-earth isotopes and neutron-deficient americium isotopes was carried out using a gas-jet coupled thermal ion source installed in the JAERI on-line isotope separator (JAERI-ISOL). New isotopes b166Tb and d165Gd produced in the proton-induced fission of 238U were identified. The half-lives were 21+/-6 s for b166Tb and 10.3+/-1.6 s for d.165Gd. Pu KX-rays associated with EC decays of americium isotopes produced in heavy-ion induced reactions were observed in the X/γ-ray spectra for the mass separated fraction of 237 and 236.

  5. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a non...

  6. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a non...

  7. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a non...

  8. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of this...

  9. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a non...

  10. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a non...

  11. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of this...

  12. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  13. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  14. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  15. Neptunium and americium speciation in selected basalt, granite, shale, and tuff ground waters

    USGS Publications Warehouse

    Cleveland, J.M.; Rees, T.F.; Nash, K.L.

    1983-01-01

    Neptunium and americium are relatively insoluble in ground waters containing high sulfate concentrations, particularly at 90??C. The insoluble neptunium species is Np(IV); hence reducing waters should enhance its formation. Americium can exist only in the trivalent state under these conditions, and its solubility also should be representative of that of curium.

  16. Uncertainty analysis of doses from ingestion of plutonium and americium.

    PubMed

    Puncher, M; Harrison, J D

    2012-02-01

    Uncertainty analyses have been performed on the biokinetic model for americium currently used by the International Commission on Radiological Protection (ICRP), and the model for plutonium recently derived by Leggett, considering acute intakes by ingestion by adult members of the public. The analyses calculated distributions of doses per unit intake. Those parameters having the greatest impact on prospective doses were identified by sensitivity analysis; the most important were the fraction absorbed from the alimentary tract, f(1), and rates of uptake from blood to bone surfaces. Probability distributions were selected based on the observed distribution of plutonium and americium in human subjects where possible; the distributions for f(1) reflected uncertainty on the average value of this parameter for non-specified plutonium and americium compounds ingested by adult members of the public. The calculated distributions of effective doses for ingested (239)Pu and (241)Am were well described by log-normal distributions, with doses varying by around a factor of 3 above and below the central values; the distributions contain the current ICRP Publication 67 dose coefficients for ingestion of (239)Pu and (241)Am by adult members of the public. Uncertainty on f(1) values had the greatest impact on doses, particularly effective dose. It is concluded that: (1) more precise data on f(1) values would have a greater effect in reducing uncertainties on doses from ingested (239)Pu and (241)Am, than reducing uncertainty on other model parameter values and (2) the results support the dose coefficients (Sv Bq(-1) intake) derived by ICRP for ingestion of (239)Pu and (241)Am by adult members of the public.

  17. Preferential decorporation of americium by pulmonary administration of DTPA dry powder after inhalation of aged PuO(2) containing americium in rats.

    PubMed

    Grémy, Olivier; Tsapis, Nicolas; Chau, Quang; Renault, Daniel; Abram, Marie-Claire; Van der Meeren, Anne

    2010-11-01

    After inhalation of plutonium oxides containing various percentages of americium in rats, we identified an acellular transient pulmonary compartment, the epithelial lining fluid (ELF), in which a fraction of actinide oxides dissolve prior to absorption and subsequent extrapulmonary deposit. Chelation therapy is usually considered to be poorly efficient after inhalation of actinide oxides. However, in the present study, prompt pulmonary administration of diethylenetraminepentaacetic acid (DTPA) as a dry powder led to a decrease in actinide content in ELF together with a limitation of bone and liver deposits. Because americium is more soluble than plutonium, higher amounts of americium were found in ELF, extrapulmonary tissues and urine. Our results also demonstrated that the higher efficacy of DTPA on americium compared to plutonium in ELF induced a preferential inhibition of extrapulmonary deposit and a greater urinary excretion of americium compared to plutonium. All together, our data justify the use of an early and local DTPA treatment after inhalation of plutonium oxide aerosols in which americium can be in high proportion such as in aged compounds.

  18. High pressure phase transition and elastic properties of americium telluride

    NASA Astrophysics Data System (ADS)

    Aynyas, Mahendra; Rukmangad, Aditi; Arya, B. S.; Sanyal, S. P.

    2013-06-01

    The structural and elastic properties of Americium Telluride (AmTe) have been investigated by using a modified inter-ionic potential theory (MIPT). This theory is capable of explaining first order phase transition with a crystallographic change NaCl to CsCl structure for this compound. The values of optimized lattice constant, phase transition pressure, zero pressure bulk modulus and second order elastic constants (C11, C44) agree well with their corresponding experimental data. Debye temperature (θD) is also calculated for this compound for the first time.

  19. Quantitative NDA measurements of advanced reprocessing product materials containing uranium, neptunium, plutonium, and americium

    NASA Astrophysics Data System (ADS)

    Goddard, Braden

    The ability of inspection agencies and facility operators to measure powders containing several actinides is increasingly necessary as new reprocessing techniques and fuel forms are being developed. These powders are difficult to measure with nondestructive assay (NDA) techniques because neutrons emitted from induced and spontaneous fission of different nuclides are very similar. A neutron multiplicity technique based on first principle methods was developed to measure these powders by exploiting isotope-specific nuclear properties, such as the energy-dependent fission cross sections and the neutron induced fission neutron multiplicity. This technique was tested through extensive simulations using the Monte Carlo N-Particle eXtended (MCNPX) code and by one measurement campaign using the Active Well Coincidence Counter (AWCC) and two measurement campaigns using the Epithermal Neutron Multiplicity Counter (ENMC) with various (alpha,n) sources and actinide materials. Four potential applications of this first principle technique have been identified: (1) quantitative measurement of uranium, neptunium, plutonium, and americium materials; (2) quantitative measurement of mixed oxide (MOX) materials; (3) quantitative measurement of uranium materials; and (4) weapons verification in arms control agreements. This technique still has several challenges which need to be overcome, the largest of these being the challenge of having high-precision active and passive measurements to produce results with acceptably small uncertainties.

  20. Comparative biokinetics of trivalent radionuclides with similar ionic dimensions: promethium-147, curium-242 and americium-241.

    PubMed

    Priest, N D

    2007-09-01

    Data on the distribution and redistribution patterns in the laboratory rat of three trivalent elements with a similar ionic radius have been compared. This showed that these distributions for the two ions with the same ionic radius (111 pm), i.e., those of promethium (a lanthanoid) and curium (an actinoid), were indistinguishable and that americium, with a slightly larger ion size (111.5 pm), behaved similarly. The results are consistent with the suggestion that ion size is the only important factor controlling the deposition and redistribution patterns of trivalent lanthanoids and actinoids in rats. The result is important because it suggests that the same radiological protection dosimetry models should be used for trivalent actinoids and lanthanoids, that human volunteer data generated for lanthanoid isotopes can be used to predict the behavior of actinoids with the same ion size, and that appropriate pairs of beta-particle-emitting lanthanoid and alpha-particle-emitting actinoids could be used to study the relative toxicity of alpha and beta particles in experimental animals.

  1. Extraction of americium in different oxidation states in a two-phase aqueous system based on poly(ethylene glycol)

    SciTech Connect

    Molochnikova, N.P.; Frenkel', B.F.; Myasoedov, B.F.; Shkinev, V.M.; Spivakov, B.Ya.; Zolotov, Yu.A.

    1987-09-01

    The extraction of americium in different states of oxidation was studied in a two-phase aqueous system based on poly(ethylene glycol). Conditions were found for the quantitative extraction of americium (III) and americium (V) from solutions of ammonium sulfate in the pH range of 3-5 and in the presence of arsenazo III. The composition of the complexes of americium with the reagent was determined; americium (III) reacts with arsenazo III in solutions of ammonium sulfate to form complexes with the composition of MeR and Me/sub 2/R. Characteristics of the absorption spectra of complexes of americium (III) and (V) with arsenazo III in ammonium sulfate solutions and in extracts based on aqueous solutions of poly(ethylene glycol) were found. The molar extinction coefficients of complexes of americium with arsenazo III were determined in these solutions.

  2. The biodistribution and toxicity of plutonium, americium and neptunium.

    PubMed

    Taylor, D M

    1989-07-15

    In the nuclear fuel cycle the transuranic radionuclides plutonium-239, americium-241 and neptunium-237 would probably present the most serious hazard to human health if released into the environment. Despite differences in their solution chemistry the three elements exhibit remarkable similarity in their biochemical behaviour, apparently sharing similar transport pathways in blood and cells. After entering the blood the elements deposit predominantly in liver and skeleton, where retention appears to be prolonged, with half-times of the order of years. The principal late effects of all three radionuclides are the induction of cancers of bone, lung or liver. For the latter tumours the induction risk per unit radiation dose appears similar for the three radionuclides. But in bone there are indications that, due to microscopic differences in the distribution of the alpha-particle radiation dose, the efficiency of bone cancer induction may increase in the order americium-241 less than plutonium-239 less than neptunium-237. No case of human cancer induced by these radionuclides is known.

  3. A Density Functional Study of the Americium (001) Surface

    NASA Astrophysics Data System (ADS)

    Gao, Da; Ray, Asok Kumar

    2006-03-01

    Electronic structure properties of the fcc americium (001) surface, modeled by periodically repeated fcc Am (001) surface slabs, have been studied with the full-potential linearized augmented plane wave (FP-LAPW) method. The alternative basis set APW+lo is used inside the atomic spheres for chemically important orbitals that are difficult to converge, whereas LAPW is used for others. The core states are treated fully relativistically and for valence states, two levels of treatments are implemented: (1) a scalar relativistic scheme including the mass-velocity correction and the Darwin s-shift and (2) a fully relativistic scheme with spin-orbit coupling included in a second variational treatment using the scalar-relativistic eigenfunctions as basis. Our results indicate that the ground state of Am (001) surface is anti-ferromagnetic. The quantum size effects in the surface energies and the work functions of the (001) fcc americium ultra thin films (UTF) have been examined up to seven layers. In addition, the Am (001) surface properties are compared with our earlier study of the Am (111) surface.

  4. XAFS study of americium sorbed onto groundwater colloids.

    PubMed

    Degueldre, Claude; Reed, Donald; Kropf, A Jeremy; Mertz, Carol

    2004-03-01

    The sorption of americium, as Am(III), onto groundwater colloids obtained from a marl aquifer was studied in 2 x 10(-2)M sodium bicarbonate groundwater and 2 x 10(-2)M sodium chloride bicarbonate-free solutions. At the in situ groundwater pH of 8.6, the americium was strongly sorbed onto the colloids. XAFS analyses were performed on these sorbed Am species to establish the oxidation state and its near-neighbour bonding. These XAFS data, obtained at 400 mg l(-1) colloid concentrations and total Am concentration of 1.53 x 10(-5)M (dissolved and onto colloids), indicated that Am remains trivalent, and that surface complexes are formed with the colloids without surface precipitation. This conclusion is based on the absence of Am-Am interactions in the second or third shells. The surface complexes generated by the Am(III) sorbed onto active sites are described on the basis of the XAFS data. They include the presence of about seven water molecules around the ternary surface complexes of this trivalent actinide.

  5. Kilogram-scale purification of americium by ion exchange

    SciTech Connect

    Wheelwright, E.J.

    1980-05-01

    Sequential anion and cation exchange processes have been used for the final purification of /sup 241/Am recovered during the reprocessing of aged plutonium metallurgical scrap. Plutonium was removed by absorption on Dowex 1, X-3.5 (30 to 50 mesh) anion exchange resin from 6.5 to 7.5 M HNO/sub 3/ feed solution. Following a water dilution to 0.75 to 1.0 M HNO/sub 3/, americium was absorbed on Dowex 50W, X-8 (50 to 100 mesh) cation exchange resin. Final purification was accomplished by elution of the absorbed band down 3 to 4 successive beds of the same resin, preloaded with Zn/sup 2+/, with an NH/sub 4/OH buffered chelating agent. The recovery of mixed /sup 241/Am-/sup 243/Am from power reactor reprocessing waste has been demonstrated. Solvent extraction was used to recover a HNO/sub 3/ solution of mixed lanthanides and actinides from waste generated by the reprocessing of 13.5 tons of Shippingport Power Reactor blanket fuel. Sequential cation exchange band-displacement processes were then used to separate americium and curium from the lanthanides and then to separate approx. 60 g of /sup 244/Cm from 1000 g of mixed /sup 241/Am-/sup 243/Am.

  6. Americium Transmutation Feasibility When Used as Burnable Absorbers - 12392

    SciTech Connect

    Barbaras, Sean A.; Knight, Travis W.

    2012-07-01

    The use of plutonium in Mixed Oxide (MOX) fuel in traditional Pressurized Water Reactor (PWR) assemblies leads to greater americium production which is not addressed in MOX recycling. The transuranic nuclides (TRU) contribute the most to the radiotoxicity of nuclear waste and a reduction of the TRU stockpile would greatly reduce the overall radiotoxicity of what must be managed. Am-241 is a TRU of particular concern because it is the dominant contributor of total radiotoxicity for the first 1000 years in a repository. This research explored the feasibility of transmuting Am-241 by using varying amounts in MOX rods being used in place of burnable absorbers and evaluated with respect to the impact on incineration and transmutation of transuranics in MOX fuel as well as the impact on safety. This research concludes that the addition of americium to a non-uniform fuel assembly is a viable method of transmuting Am-241, holding down excess reactivity in the core while serving as a burnable poison, as well as reducing the radiotoxicity of high level waste that must be managed. The use of Am/MOX hybrid fuel assemblies to transmute americium was researched using multiple computer codes. Am-241 was shown in this study to be able to hold down excess reactivity at the beginning of cycle and shape the power distribution in the core with assemblies of varying americium content loaded in a pattern similar to the traditional use of assemblies with varying amounts of burnable absorbers. The feasibility, safety, and utility of using americium to create an Am/MOX hybrid non-uniform core were also evaluated. The core remained critical to a burnup of 22,000 MWD/MTM. The power coefficient of reactivity as well as the temperature and power defects were sufficiently negative to provide a prompt feedback mechanism in case of a transient and prevent a power excursion, thus ensuring inherent safety and protection of the core. As shown here as well as many other studies, this non

  7. A review on the mass spectrometric studies of americium: Present status and future perspective.

    PubMed

    Aggarwal, Suresh Kumar

    2016-05-06

    The manuscript reviews the various mass spectrometric techniques for analysis and chemical studies of Americium. These methods include thermal ionization mass spectrometry (TIMS), and inductively coupled plasma source mass spectrometry (ICPMS) for the determination of Am isotope ratios and concentration in nuclear fuel samples of interest in nuclear technology, and in complex biological and environmental samples. Ultra-sensitive mass spectrometric techniques of resonance-ionization mass spectrometry (RIMS), and accelerator-based mass spectrometry (AMS) are also discussed. The novel applications of electrospray ionization mass spectrometry (ESIMS) to understand the solution chemistry of Am and other actinides are presented. These studies are important in view of the world-wide efforts to develop novel complexing agents to separate lanthanides and minor actinides (Am, Np, and Cm) for partitioning and transmutation of minor actinides from the point of view of nuclear waste management. These mass spectrometry experiments are also of great interest to examine the covalent character of actinides with increasing atomic number. Studies on gas-phase chemistry of Am and its oxides with Knudsen effusion mass spectrometry (KEMS), Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS), and laser-based experiments with reflectron time-of-flight mass spectrometer (R-ToF) are highlighted. These studies are important to understand the fundamental chemistry of 5f electrons in actinides. Requirement of certified isotopic reference materials of Am to improve the accuracy of experimental nuclear data (e.g., the half-life of (243) Am) is emphasized. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

  8. Comparison of cation exchange resins for recovering americium and plutonium from chloride wastes

    SciTech Connect

    Silva, R.A.; Smith, C.M.; Navratil, J.D.; Thompson, G.H.

    1984-04-25

    Macroreticular and microreticular cation exchange resins were compared for their capability of recovering americium and plutonium from solutions of calcium, magnesium, potassium, and sodium chlorides. Americium and plutonium breakthrough capacity and elution behavior of the resins were determined. Of the resins tested, Dowex MSC-1 was selected as the most efficient because of its favorable capacity and excellent elution behavior. Actinide eluting agents were also studied. More concentrated (9.0M) nitric acid was found to elute plutonium faster than 7.0M HNO/sub 3/ used previously, while 7.0M HNO/sub 3/-0.1M NANO/sub 2/ eluted americium fastest.

  9. Relativistic density functional theory modeling of plutonium and americium higher oxide molecules.

    PubMed

    Zaitsevskii, Andréi; Mosyagin, Nikolai S; Titov, Anatoly V; Kiselev, Yuri M

    2013-07-21

    The results of electronic structure modeling of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two-component relativistic density functional theory are presented. Ground-state equilibrium molecular structures, main features of charge distributions, and energetics of AnO3, AnO4, An2On (An=Pu, Am), and PuAmOn, n = 6-8, are determined. In all cases, molecular geometries of americium and mixed plutonium-americium oxides are similar to those of the corresponding plutonium compounds, though chemical bonding in americium oxides is markedly weaker. Relatively high stability of the mixed heptoxide PuAmO7 is noticed; the Pu(VIII) and especially Am(VIII) oxides are expected to be unstable.

  10. Relativistic density functional theory modeling of plutonium and americium higher oxide molecules

    NASA Astrophysics Data System (ADS)

    Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M.

    2013-07-01

    The results of electronic structure modeling of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two-component relativistic density functional theory are presented. Ground-state equilibrium molecular structures, main features of charge distributions, and energetics of AnO3, AnO4, An2On (An=Pu, Am), and PuAmOn, n = 6-8, are determined. In all cases, molecular geometries of americium and mixed plutonium-americium oxides are similar to those of the corresponding plutonium compounds, though chemical bonding in americium oxides is markedly weaker. Relatively high stability of the mixed heptoxide PuAmO7 is noticed; the Pu(VIII) and especially Am(VIII) oxides are expected to be unstable.

  11. The 1976 Hanford Americium Accident: Then and Now

    SciTech Connect

    Carbaugh, Eugene H.

    2013-10-02

    The 1976 chemical explosion of an 241Am ion exchange column at a Hanford Site waste management facility resulted in the extreme contamination of a worker with 241Am, nitric acid and debris. The worker underwent medical treatment for acid burns, as well as wound debridement, extensive personal skin decontamination and long-term DTPA chelation therapy for decorporation of americium-241. Because of the contamination levels and prolonged decontamination efforts, care was provided for the first three months at the unique Emergency Decontamination Facility with gradual transition to the patient’s home occurring over another two months. The medical treatment, management, and dosimetry of the patient have been well documented in numerous reports and journal articles. The lessons learned with regard to patient treatment and effectiveness of therapy still form the underlying philosophy of treatment for contaminated injuries. Changes in infrastructure and facilities as well as societal expectations make for interesting speculation as to how responses might differ today.

  12. Separation of americium from curium by oxidation and ion exchange.

    PubMed

    Burns, Jonathan D; Shehee, Thomas C; Clearfield, Abraham; Hobbs, David T

    2012-08-21

    Nuclear energy has the potential to be a clean alternative to fossil fuels, but in order for it to play a major role in the US, many questions about the back end of the fuel cycle must be addressed. One of these questions is the difficult separation of americium from curium. Here, we report the oxidation of Am in two systems, perchloric acid and nitric acid and the affect of changing the acid has on the oxidation. K(d) values were observed and a direct separation factor was calculated and was seen to be as high as 20 for four metal(IV) pillared phosphate phosphonate inorganic organic hybrid ion exchange materials. These ion exchangers are characterized by very low selectivity for cations with low charge but extremely high uptake of ions of high charge.

  13. 1976 Hanford americium exposure incident: in vivo measurements

    SciTech Connect

    Palmer, H.E.; Rieksts, G.A.; Icayan, E.E.

    1982-01-01

    Detailed external measurement were made of internally deposited /sup 241/Am in a nuclear chemical operator involved in an americium exposure accident at the Hanford plant. Despite some interference from high-level external contamination, quantitative measurements of the /sup 241/Am content in the lung, liver, and bones were made starting on the third day after the accident. The rate of excretion of /sup 241/Am from these organs was determined. The /sup 241/Am embedded in the skin of the face and head was carefully mapped. The distribution over the total length of the body was also determined. Linear and rectilinear scanners, gamma cameras, large and small scintillation detectors, proportional counters, and Si(Li) and intrinsic germanium detectors were used to evaluate the internal deposition. Methods of calibration for quantitative measurement included simulation of the /sup 241/Am activity in both phantom and cadaver parts.

  14. The biokinetics and radiotoxicology of curium: a comparison with americium.

    PubMed

    Ménétrier, F; Taylor, D M; Comte, A

    2008-05-01

    The human and animal data on the biokinetics of (242)Cm and (244)Cm are reviewed and shown to be very similar to those for (241)Am. Liver and skeleton are the main organs of deposition and the retention of curium in the skeleton is very prolonged in all the species examined. Retention of both curium and americium in the liver appears to be species-dependent, being relatively rapidly removed from the liver of rats, and probably humans, but being tenaciously retained in dogs and some other species. The radiotoxicity of curium is also reviewed and it is shown that, as with (241)Am, lung and bone tumour induction are the major hazards from inhaled and systemically deposited (244)Cm. The use of chelating agents for the treatment of accidental contamination of the human body with (242,244)Cm is also discussed.

  15. Monte Carlo modeling of spallation targets containing uranium and americium

    NASA Astrophysics Data System (ADS)

    Malyshkin, Yury; Pshenichnov, Igor; Mishustin, Igor; Greiner, Walter

    2014-09-01

    Neutron production and transport in spallation targets made of uranium and americium are studied with a Geant4-based code MCADS (Monte Carlo model for Accelerator Driven Systems). A good agreement of MCADS results with experimental data on neutron- and proton-induced reactions on 241Am and 243Am nuclei allows to use this model for simulations with extended Am targets. It was demonstrated that MCADS model can be used for calculating the values of critical mass for 233,235U, 237Np, 239Pu and 241Am. Several geometry options and material compositions (U, U + Am, Am, Am2O3) are considered for spallation targets to be used in Accelerator Driven Systems. All considered options operate as deep subcritical targets having neutron multiplication factor of k∼0.5. It is found that more than 4 kg of Am can be burned in one spallation target during the first year of operation.

  16. Plutonium, americium, and neptunium speciation in selected groundwaters

    USGS Publications Warehouse

    Cleveland, J.M.; Rees, T.F.; Nash, K.L.

    1985-01-01

    Speciation was determined at 25 and 90 degree C in four groundwaters from diverse sources: the Sparta aquifer in Louisiana, near the Vacherie salt dome; Mansfield No. 2 well in the Palo Duro Basin, Texas; the Stripa mine in Sweden; and the Waste Isolation Pilot Plant in New Mexico. Neptunium generally was soluble in all waters and was present exclusively as Np(V) and Np(VI), regardless of initial oxidation state. The results indicated that plutonium and neptunium solubilities were determined by the oxidation-reduction properties of the waters, i. e. , their abilities to convert these elements to soluble oxidation states. This was not the case for americium, however; Am(IV) was not detected, and the solubility of this element was determined entirely by the chemical properties of Am(III).

  17. Evaluation of three electrodeposition procedures for uranium, plutonium and americium.

    PubMed

    Oh, Jung-Suk; Warwick, Phillip E; Croudace, Ian W; Lee, Sang-Han

    2014-05-01

    While both mass spectrometry and alpha-particle spectrometry have been widely used for measuring alpha activities, the former is preferred since many laboratories are not equipped with ICP-MS and MC-ICP-MS systems. In this study, three electrodeposition techniques using ammonium chloride, ammonium oxalate and ammonium sulphate as electrolyte solutions were applied and evaluated for the preparation of uranium, plutonium and americium sources for alpha-particle spectrometry. Changes in pH and temperature throughout the electrodeposition process were measured every 15 min, together with percentage deposition every 30 min. The percentage deposition in each method was checked at 300, 400 and 500 mA, and the optimised time and current were determined.

  18. Selective recognition of americium by peptide-based reagents.

    PubMed

    Özçubukçu, Salih; Mandal, Kalyanaswer; Wegner, Seraphine; Jensen, Mark P; He, Chuan

    2011-09-05

    The separation of lanthanides from minor actinides such as americium and curium is an important step during the recycling process in the treatment of nuclear waste. However, the similar chemistry and ionic size of lanthanide and actinide ions make the separation challenging. Here, we report that a peptide-based reagent can selectively bind trivalent actinides over trivalent lanthanides by means of introducing soft-donor atoms into a peptide known as a lanthanide-binding tag (LBT). Fluorescence spectroscopy has been used to measure the dissociation constant of each metal/peptide complex. A 10-fold selectivity was obtained for Am(3+) over the similarly sized lanthanide cation, Nd(3+), when the asparagine on the fifth position of a LBT was mutated to a cysteine and further functionalized by a pyridine moiety.

  19. Hexavalent Americium recovery using Copper(III) periodate

    SciTech Connect

    McCann, Kevin; Brigham, Derek M.; Morrison, Samuel; Braley, Jenifer C.

    2016-10-31

    Separation of americium from the lanthanides is considered one of the most difficult separation steps in closing the nuclear fuel cycle. One approach to this separation could involve oxidizing americium to the hexavalent state to form a linear dioxo cation while the lanthanides remain as trivalent ions. This work considers aqueous soluble Cu3+ periodate as an oxidant under molar nitric acid conditions to separate hexavalent Am with diamyl amylphosphonate (DAAP) in n-dodecane. Initial studies assessed the kinetics of Cu3+ periodate autoreduction in acidic media to aid in development of the solvent extraction system. Following characterization of the Cu3+ periodate oxidant, solvent extraction studies optimized the recovery of Am from varied nitric acid media and in the presence of other fission product, or fission product surrogate, species. Short aqueous/organic contact times encouraged successful recovery of Am (distribution values as high as 2) from nitric acid media in the absence of redox active fission products. In the presence of a post-plutonium uranium redox extraction (post-PUREX) simulant aqueous feed, precipitation of tetravalent species (Ce, Ru, Zr) occurred and the distribution values of 241Am were suppressed, suggesting some oxidizing capacity of the Cu3+ periodate is significantly consumed by other redox active metals in the simulant. Furthermore, the manuscript demonstrates Cu3+ periodate as a potentially viable oxidant for Am oxidation and recovery and notes the consumption of oxidizing capacity observed in the presence of the post-PUREX simulant feed will need to be addressed for any approach seeking to oxidize Am for separations relevant to the nuclear fuel cycle.

  20. Hexavalent Americium recovery using Copper(III) periodate

    DOE PAGES

    McCann, Kevin; Brigham, Derek M.; Morrison, Samuel; ...

    2016-10-31

    Separation of americium from the lanthanides is considered one of the most difficult separation steps in closing the nuclear fuel cycle. One approach to this separation could involve oxidizing americium to the hexavalent state to form a linear dioxo cation while the lanthanides remain as trivalent ions. This work considers aqueous soluble Cu3+ periodate as an oxidant under molar nitric acid conditions to separate hexavalent Am with diamyl amylphosphonate (DAAP) in n-dodecane. Initial studies assessed the kinetics of Cu3+ periodate autoreduction in acidic media to aid in development of the solvent extraction system. Following characterization of the Cu3+ periodate oxidant,more » solvent extraction studies optimized the recovery of Am from varied nitric acid media and in the presence of other fission product, or fission product surrogate, species. Short aqueous/organic contact times encouraged successful recovery of Am (distribution values as high as 2) from nitric acid media in the absence of redox active fission products. In the presence of a post-plutonium uranium redox extraction (post-PUREX) simulant aqueous feed, precipitation of tetravalent species (Ce, Ru, Zr) occurred and the distribution values of 241Am were suppressed, suggesting some oxidizing capacity of the Cu3+ periodate is significantly consumed by other redox active metals in the simulant. Furthermore, the manuscript demonstrates Cu3+ periodate as a potentially viable oxidant for Am oxidation and recovery and notes the consumption of oxidizing capacity observed in the presence of the post-PUREX simulant feed will need to be addressed for any approach seeking to oxidize Am for separations relevant to the nuclear fuel cycle.« less

  1. Hexavalent Americium Recovery Using Copper(III) Periodate

    SciTech Connect

    McCann, Kevin; Brigham, Derek M.; Morrison, Samuel; Braley, Jenifer C.

    2016-11-21

    Separation of americium from the lanthanides is considered one of the most difficult separation steps in closing the nuclear fuel cycle. One approach to this separation could involve oxidizing americium to the hexavalent state to form a linear dioxo cation while the lanthanides remain as trivalent ions. This work considers aqueous soluble Cu3+ periodate as an oxidant under molar nitric acid conditions to separate hexavalent Am with diamyl amylphosphonate (DAAP) in n-dodecane. Initial studies assessed the kinetics of Cu3+ periodate auto-reduction in acidic media to aid in development of the solvent extraction system. Following characterization of the Cu3+ periodate oxidant, solvent extraction studies optimized the recovery of Am from varied nitric acid media and in the presence of other fission product, or fission product surrogate, species. Short aqueous/organic contact times encouraged successful recovery of Am (distribution values as high as 2) from nitric acid media in the absence of redox active fission products. In the presence of a post-PUREX simulant aqueous feed, precipitation of tetravalent species (Ce, Ru, Zr) occurred and the distribution values of 241Am were suppressed, suggesting some oxidizing capacity of the Cu3+ periodate is significantly consumed by other redox active metals in the simulant. The manuscript demonstrates Cu3+ periodate as a potentially viable oxidant for Am oxidation and recovery and notes the consumption of oxidizing capacity observed in the presence of the post-PUREX simulant feed will need to be addressed for any approach seeking to oxidize Am for separations relevant to the nuclear fuel cycle.

  2. Hexavalent Americium Recovery Using Copper(III) Periodate.

    PubMed

    McCann, Kevin; Brigham, Derek M; Morrison, Samuel; Braley, Jenifer C

    2016-11-21

    Separation of americium from the lanthanides is considered one of the most difficult separation steps in closing the nuclear fuel cycle. One approach to this separation could involve oxidizing americium to the hexavalent state to form a linear dioxo cation while the lanthanides remain as trivalent ions. This work considers aqueous soluble Cu(3+) periodate as an oxidant under molar nitric acid conditions to separate hexavalent Am with diamyl amylphosphonate (DAAP) in n-dodecane. Initial studies assessed the kinetics of Cu(3+) periodate autoreduction in acidic media to aid in development of the solvent extraction system. Following characterization of the Cu(3+) periodate oxidant, solvent extraction studies optimized the recovery of Am from varied nitric acid media and in the presence of other fission product, or fission product surrogate, species. Short aqueous/organic contact times encouraged successful recovery of Am (distribution values as high as 2) from nitric acid media in the absence of redox active fission products. In the presence of a post-plutonium uranium redox extraction (post-PUREX) simulant aqueous feed, precipitation of tetravalent species (Ce, Ru, Zr) occurred and the distribution values of (241)Am were suppressed, suggesting some oxidizing capacity of the Cu(3+) periodate is significantly consumed by other redox active metals in the simulant. The manuscript demonstrates Cu(3+) periodate as a potentially viable oxidant for Am oxidation and recovery and notes the consumption of oxidizing capacity observed in the presence of the post-PUREX simulant feed will need to be addressed for any approach seeking to oxidize Am for separations relevant to the nuclear fuel cycle.

  3. Concentrations of plutonium and americium in plankton from the western Mediterranean Sea.

    PubMed

    Sanchez-Cabeza, Joan-Albert; Merino, Juan; Masqué, Pere; Mitchell, Peter I; Vintró, L León; Schell, William R; Cross, Lluïsa; Calbet, Albert

    2003-07-20

    Understanding the transfer of radionuclides through the food chain leading to man and in particular, the uptake of transuranic nuclides by plankton, is basic to assess the potential radiological risk of the consumption of marine products by man. The main sources of transuranic elements in the Mediterranean Sea in the past were global fallout and the Palomares accident, although at present smaller amounts are released from nuclear establishments in the northwestern region. Plankton from the western Mediterranean Sea was collected and analyzed for plutonium and americium in order to study their biological uptake. The microplankton fractions accounted for approximately 50% of the total plutonium contents in particulate form. At Garrucha (Palomares area), microplankton showed much higher 239,240 Pu activity, indicating the contamination with plutonium from the bottom sediments. Concentration factors were within the range of the values recommended by the International Atomic Energy Agency. Continental shelf mesoplankton was observed to efficiently concentrate transuranics. In open seawaters, concentrations were much lower. We speculate that sediments might play a role in the transfer of transuranics to mesoplankton in coastal waters, although we cannot discard that the difference in species composition may also play a role. In Palomares, both 239,240 Pu and 241Am showed activities five times higher than the mean values observed in continental shelf mesoplankton. As the plutonium isotopic ratios in the contaminated sample were similar to those found in material related to the accident, the contamination was attributed to bomb debris from the Palomares accident. Concentration factors in mesoplankton were also in relatively good agreement with the ranges recommended by IAEA. In the Palomares station the highest concentration factor was observed in the sample that showed predominance of the dynoflagellate Ceratium spp. Mean values of the enrichment factors showed, on

  4. Characterization of a Sealed Americium-Beryllium (AmBe) Source by Inductively Coupled Plasma Mass Spectrometry

    SciTech Connect

    James Sommers; Marcos Jimenez; Mary Adamic; Jeffrey Giglio; Kevin Carney

    2009-12-01

    Two Americium-Beryllium neutron sources were dismantled, sampled (sub-sampled) and analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Characteristics such as “age” since purification, actinide content, trace metal content and inter and intra source composition were determined. The “age” since purification of the two sources was determined to be 25.0 and 25.4 years, respectively. The systematic errors in the “age” determination were ± 4 % 2s. The amount and isotopic composition of U and Pu varied substantially between the sub-samples of Source 2 (n=8). This may be due to the physical means of sub-sampling or the way the source was manufactured. Source 1 was much more consistent in terms of content and isotopic composition (n=3 sub-samples). The Be-Am ratio varied greatly between the two sources. Source 1 had an Am-Be ratio of 6.3 ± 52 % (1s). Source 2 had an Am-Be ratio of 9.81 ± 3.5 % (1s). In addition, the trace element content between the samples varied greatly. Significant differences were determined between Source 1 and 2 for Sc, Sr, Y, Zr, Mo, Ba and W.

  5. Electronic, mechanical, and thermodynamic properties of americium dioxide

    NASA Astrophysics Data System (ADS)

    Lu, Yong; Yang, Yu; Zheng, Fawei; Wang, Bao-Tian; Zhang, Ping

    2013-10-01

    By performing density functional theory (DFT) +U calculations, we systematically study the electronic, mechanical, tensile, and thermodynamic properties of AmO2. It is found that the chemical bonding character in AmO2 is similar to that in PuO2, with smaller charge transfer and stronger covalent interactions between americium and oxygen atoms. The stress-strain relationship of AmO2 is examined along the three low-index directions, showing that the [1 0 0] and [1 1 1] directions are the strongest and weakest tensile directions, respectively, but the theoretical tensile strengths of AmO2 are smaller than those of PuO2. The phonon dispersion curves of AmO2 are calculated and the heat capacities as well as lattice expansion curve are subsequently determined. The lattice thermal conductivity of AmO2 is further evaluated and compared with attainable experiments. Our present work integrally reveals various physical properties of AmO2 and can be referenced for technological applications of AmO2 based materials.

  6. Effect of americium-241 on luminous bacteria. Role of peroxides.

    PubMed

    Alexandrova, M; Rozhko, T; Vydryakova, G; Kudryasheva, N

    2011-04-01

    The effect of americium-241 ((241)Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of (241)Am in nutrient media (0.16-6.67 kBq/L) suppressed the growth of bacteria, but enhanced luminescence intensity and quantum yield at room temperature. Lower temperature (4 °C) increased the time of bacterial luminescence and revealed a stage of bioluminescence inhibition after 150 h of bioluminescence registration start. The role of conditions of exposure the bacterial cells to the (241)Am is discussed. The effect of (241)Am on luminous bacteria was attributed to peroxide compounds generated in water solutions as secondary products of radioactive decay. Increase of peroxide concentration in (241)Am solutions was demonstrated; and the similarity of (241)Am and hydrogen peroxide effects on bacterial luminescence was revealed. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha-emitting radionuclides in aquatic solutions.

  7. The availability of plutonium and americium in Irish Sea sediments for re-dissolution.

    PubMed

    McDonald, P; Vives i Batlle, J; Bousher, A; Whittall, A; Chambers, N

    2001-02-21

    The availability of plutonium and americium, for re-dissolution from offshore sediments into Irish Sea water, has been examined. Sediments collected from the mud-patch near the Cumbrian coast were characterized in terms of spatial location, particle size, partitioning of radionuclides with respect to physico-chemical bonds and availability of actinides for release into seawater. Sequential extraction investigations revealed that plutonium was predominantly associated with strongly bound sesquioxide and organic complex fractions. Americium was associated mainly with the organic complex fraction, but a significant fraction was in carbonate form. Sediment/water re-dissolution experiments with and without stirring were compared to simulate the effect of disturbing bed sediment. After 1 week, neither set of re-dissolution data provided significant trends between dissolved activity and time. Stirred systems appeared to release 2.5 times more plutonium and americium into seawater than unstirred systems. Measured 239,240Pu and 241Am distribution coefficients (Kd values) were both typically approximately 10(5) l kg(-1). 241Am Kd values are an order of magnitude lower than previously reported for the north-eastern Irish Sea, but similar to western Irish Sea values. Overall, the fractions of plutonium and americium available for re-dissolution from bed sediment are very low at < 0.1%, with proportionally more plutonium being released than americium. These findings lend further support for the extrapolation of laboratory-derived information to environmental conditions.

  8. Environmental impact of a teratogenic actinide: a case study of americium-241

    SciTech Connect

    Wang, J.; Yang, J.Y.

    1985-10-16

    Americium-241 is widely used as a radiation source, but it also has some potential risk if taken into the body. Although the radiotoxicity of americium-241 is small compared to other transuranic actinides, its effects on the reproductive system and on development of the placenta are more damaging than the effects of plutonium-239. A previous report based on a worst-case scenario involving a hypothetical fire accident in a contaminated facility indicated that there could have been a significant impact on nearby residents from a unit release of americium-241 via atmospheric dispersion. However, because the facility is located in a rural region where most drinking water supplies are drawn from private wells, it is believed that deposition of americium-241 from the atmosphere might also have impacts via the groundwater pathway by infiltration of rainwater. In this analysis, a three-dimensional analytical mathematical model is used to assess several aspects of americium-241 contamination of groundwater, including radioactive transformation, advection, dispersion, and soil sorption. Simulation results indicate that no significant radiological impacts would occur to the nearby residents via the groundwater pathway. 15 refs., 2 figs., 2 tabs.

  9. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... or radium-226: Requirements for license to manufacture or initially transfer. 32.57 Section 32.57... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of this...

  10. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... or radium-226: Requirements for license to manufacture or initially transfer. 32.57 Section 32.57... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of this...

  11. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... or radium-226: Requirements for license to manufacture or initially transfer. 32.57 Section 32.57... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of this...

  12. Comparison of cation exchange resins for recovering americium and plutonium from chloride salts

    SciTech Connect

    Silva, R.A.; Navratil, J.D.

    1983-01-01

    Macroreticular and microreticular cation exchange resins were compared for their capability of recovering americium and plutonium from solutions of calcium, magnesium, potassium, and sodium chlorides. Americium and plutonium breakthrough capacity and elution behavior of the resins were determined. Of the resins tested, Dowex MSC-1 was selected as the most efficient because of its favorable capacity and excellent elution behavior. Actinide eluting agents were also studied. More concentrated (9.0M) nitric acid was found to elute plutonium faster than 7.0M HNO/sub 3/ used previously while 7.0M HNO/sub 3/-0.1M NaNO/sub 2/ eluted americium fastest. 4 tables.

  13. Americium biokinetics in benthic organisms as a function of feeding mode

    SciTech Connect

    Fowler, S.W.; Carvalho, F.P.

    1985-12-01

    Transuranic radionuclides in the environment have arisen from nuclear weapons testing, release from nuclear waste reprocessing plants and accidents with nuclear devices. Although at present the plutonium inventory is greater than that of any other transuranium element, the americium inventory will continue to increase due to the in situ decay of SU Pu. Furthermore some studies have demonstrated that americium is more bioavailable than plutonium in aquatic environments. The authors therefore undertook to delineate, experimentally, the biokinetics of SU Am in some marine benthic species with very different feeding-digestion strategies, which hitherto have not been studied in any detail in a radioecological context.

  14. Identification of the oxidation state of americium by thin-layer chromatography using domestic plates

    SciTech Connect

    Molochnikova, N.P.; Myasoedov, B.F.

    1994-10-01

    Methods of precipitation, solvent extraction, ion exchange, and extraction chromatography were suggested to identify trace amounts of americium in different oxidation states. Thin-layer chromatography (TLC) has not been used previously for these purposes. At the same time, this method is widely used in the separation of small quantities of elements in different valence states. Previously, the chromatographic mobility of actinide ions on thin layers of silica gel and cellulose on Silufol plates (CSFR) and plates from Merck (Germany) was investigated. The behavior of americium in different oxidation states on domestic TLC plates in nitric acid solutions was determined to be of interest.

  15. Behavior of americium and berkelium ions in solutions under intense alpha radiation

    SciTech Connect

    Frolov, A.A.; Frolova, L.M.; Vasil'ev, V.Ya.

    1987-09-01

    The information in the literature on the radiation-chemical behavior of americium and berkelium is devoted mainly to the reduction of americium(V) and (VI) upon the irradiation of solutions by alpha particles formed as a result of the decay of /sup 241,243/Am and to the reduction of berkelium(IV) upon the irradiation of solutions by beta particles emitted by the nuclide /sup 249/Bk. In the present work they studied the behavior of ions of the elements indicated in perchlorate and nitrate solutions under intense internal alpha radiation. Curium-244, which was introduced into the solution, served as the source of the alpha particles.

  16. Synthesis of functionalised BTPhen derivatives - effects on solubility and americium extraction.

    PubMed

    Higginson, Matthew A; Kyle, Nichola D; Marsden, Olivia J; Thompson, Paul; Livens, Francis R; Heath, Sarah L

    2015-10-07

    Separation of the minor actinides (Am/Cm) from spent nuclear fuel post-PUREX process is expected to play a key part in new reprocessing methodologies. To date, a number of selective americium extractants from the BTPhen ligand family have been identified. In this investigation, we synthesise 24 novel BTPhens with additional functionality to determine the effects on solubilities and americium extraction capabilities. The data obtained will allow for tuning of steric/electronic properties of BTPhens in order to assist future extractant design.

  17. Apparatus for fabrication of americium- beryllium neutron sources prevents capsule contamination

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Van Loom, J. A.

    1967-01-01

    Modified gloved enclosure is used to fill a capsule with a mixture of americium and beryllium radioactive powders to seal weld the opening, and to test it for leaks. It contains a horizontal partition, vortex mixer, mounting press, welder, test vessel, and radiation shielding to prevent surface contamination.

  18. National low-level waste management program radionuclide report series, Volume 14: Americium-241

    SciTech Connect

    Winberg, M.R.; Garcia, R.S.

    1995-09-01

    This report, Volume 14 of the National Low-Level Waste Management Program Radionuclide Report Series, discusses the radiological and chemical characteristics of americium-241 ({sup 241}Am). This report also includes discussions about waste types and forms in which {sup 241}Am can be found and {sup 241}Am behavior in the environment and in the human body.

  19. Worldwide bioassay data resources for plutonium/americium internal dosimetry studies.

    PubMed

    Miller, G; Riddell, A E; Filipy, R; Bertelli, L; Little, T; Guilmette, R

    2007-01-01

    Biokinetic models are the scientific underpinning of internal dosimetry and depend, ultimately, for their scientific validation on comparisons with human bioassay data. Three significant plutonium/americium bioassay databases, known to the authors, are described: (1) Sellafield, (2) Los Alamos and (3) the United States Transuranium Registry. A case is made for a uniform standard for database format, and the XML standard is discussed.

  20. Separation of Americium in High Oxidation States from Curium Utilizing Sodium Bismuthate.

    PubMed

    Richards, Jason M; Sudowe, Ralf

    2016-05-03

    A simple separation of americium from curium would support closure of the nuclear fuel cycle, assist in nuclear forensic analysis, and allow for more accurate measurement of neutron capture properties of (241)Am. Methods for the separation of americium from curium are however complicated and time-consuming due to the similar chemical properties of these elements. In this work a novel method for the separation of americium from curium in nitric acid media was developed using sodium bismuthate to perform both the oxidation and separation. Sodium bismuthate is shown to be a promising material for performing a simple and rapid separation. Curium is more strongly retained than americium on the undissolved sodium bismuthate at nitric acid concentrations below 1.0 M. A separation factor of ∼90 was obtained in 0.1 M nitric acid. This separation factor is achieved within the first minute of contact and is maintained for at least 2 h of contact. Separations using sodium bismuthate were performed using solid-liquid extraction as well as column chromatography.

  1. Understanding the Chemistry of Uncommon Americium Oxidation States for Application to Actinide/Lanthanide Separations

    SciTech Connect

    Leigh Martin; Bruce J. Mincher; Nicholas C. Schmitt

    2007-09-01

    A spectroscopic study of the stability of Am(V) and Am(VI) produced by oxidizing Am(III) with sodium bismuthate is presented, varying the initial americium concentration, temperature and length of the oxidation was seen to have profound effects on the resultant solutions.

  2. Environmental impacts of the release of a transuranic actinide, americium-241, from a contaminated facility

    SciTech Connect

    Want, J.; Merry-Libby, P.

    1985-10-29

    Americium-241 is widely used as a radiation source, but it also has some potential risk if taken into the body because of its high dose conversion factor. Although the radiotoxicity of americium-241 is small compared to other transuranic actinides, its effects on the reproductive system and on development of the placenta are more damaging than the effects of plutonium-239. In Ohio, a gemologist's laboratory was contaminated with americium-241. Prior to decontamination of the laboratory, potential radiological impacts to the surrounding environment were assessed. A hypothetical fire accident resulting in a unit release (1 curie) was assumed. Potential radiological impacts were simulated using an atmospheric dispersion and dosimetry model with local meteorological data, population census data, and detailed information regarding the neighborhood. The results indicate that there could have been a significant impact on nearby residents from americium-241 via atmospheric dispersion if a major catastrophic release had occurred prior to contamination and decommissioning of the laboratory. 14 refs., 3 figs., 2 tabs.

  3. Americium 242m and its potential use in space applications

    NASA Astrophysics Data System (ADS)

    Benetti, P.; Cesana, A.; Cinotti, L.; Raselli, G. L.; Terrani, M.

    2006-05-01

    The isotope Am242m is an interesting nuclide as it shows one of the known highest neutron fission cross section. This could be useful in some special applications, like the nuclear reactor for space propulsion proposed by C. Rubbia. A detailed measurement of the energy transfer from the fission fragments to the gas as a function of the path and the gas type is an important item for the evaluation of the engine performances. This was carried out by means of an ionisation chamber. However the Am242m availability, in particular at high isotopic abundance, is still at present a serious drawback. A production model, experimentally tested in thermal nuclear reactors, has been used to evaluate the achievable isotopic abundances. The results are quite below 70% and advise the use of separation techniques for further enrichment. The use of Am242m for other applications like nuclear pumped laser is suggested.

  4. Calcium and zinc DTPA administration for internal contamination with plutonium-238 and americium-241.

    PubMed

    Kazzi, Ziad N; Heyl, Alexander; Ruprecht, Johann

    2012-08-01

    The accidental or intentional release of plutonium or americium can cause acute and long term adverse health effects if they enter the human body by ingestion, inhalation, or injection. These effects can be prevented by rapid removal of these radionuclides by chelators such as calcium or zinc diethylenetriaminepentaacetate (calcium or zinc DTPA). These compounds have been shown to be efficacious in enhancing the elimination of members of the actinide family particularly plutonium and americium when administered intravenously or by nebulizer. The efficacy and adverse effects profile depend on several factors that include the route of internalization of the actinide, the type, and route time of administration of the chelator, and whether the calcium or zinc salt of DTPA is used. Current and future research efforts should be directed at overcoming limitations associated with the use of these complex drugs by using innovative methods that can enhance their structural and therapeutic properties.

  5. [Study of the influence of peroral zincacin on the removing of ingested Americium].

    PubMed

    Zhorova, E S; Il'in, L A; Ivannikov, A T; Popov, B A; Parfenova, I M

    2002-01-01

    Effect of different cincacine doses was studied in rats ingesting americium citrate during 2 weeks. As a result new data showing the possibility and efficacy of per oral cincacine administration at americium intake into digestive tract have been obtained. Dose dependence of cincacine efficacy has been stated for per oral 241Am intake. Preparation administration at a dose of 25 mumol/kg reduces amount of 241Am in skeleton, liver and kidney by 93, 90 and 33%, respectively and is optimum for radionuclide removal from the body and for the prevention of its deposition in organs. Digestive system organs and kidney structure at cincacine administration at a dose of 150 and 300 mumol/kg) to the rats ingesting 241Am have been studied.

  6. [Emergency care for acute wound entering of plutonium and americium into the body (real case)].

    PubMed

    Krasniuk, V I; Gasteva, G N; Blinov, A P; Kuz'menko, L G

    2005-01-01

    The article describes a case of slowly soluble plutonium and americium compounds entering human body via skin wound. During the wound healing, the authors followed features of biokinetics of the radioactive substances, determined the major route of their excretion, evaluated efficiency of surgical d-bridement and complexation medicine (pentacin). clinical and biophysicdata collected could serve to increase efficiency of urgent therapeutic and prophylactic measures aimed to individuals with wounds contaminated with radioactive substances.

  7. Enhanced ionization efficiency in TIMS analyses of plutonium and americium using porous ion emitters

    SciTech Connect

    Baruzzini, Matthew L.; Hall, Howard L.; Watrous, Matthew G.; Spencer, Khalil J.; Stanley, Floyd E.

    2016-12-05

    Investigations of enhanced sample utilization in thermal ionization mass spectrometry (TIMS) using porous ion emitter (PIE) techniques for the analyses of trace quantities of americium and plutonium were performed. Repeat ionization efficiency (i.e., the ratio of ions detected to atoms loaded on the filament) measurements were conducted on sample sizes ranging from 10–100 pg for americium and 1–100 pg for plutonium using PIE and traditional (i.e., a single, zone-refined rhenium, flat filament ribbon with a carbon ionization enhancer) TIMS filament sources. When compared to traditional filaments, PIEs exhibited an average boost in ionization efficiency of ~550% for plutonium and ~1100% for americium. A maximum average efficiency of 1.09% was observed at a 1 pg plutonium sample loading using PIEs. Supplementary trials were conducted using newly developed platinum PIEs to analyze 10 pg mass loadings of plutonium. As a result, platinum PIEs exhibited an additional ~134% boost in ion yield over standard PIEs and ~736% over traditional filaments at the same sample loading level.

  8. Structure of a single model to describe plutonium and americium decorporation by DTPA treatments.

    PubMed

    Fritsch, P; Sérandour, A L; Grémy, O; Phan, G; Tsapis, N; Fattal, E; Benech, H; Deverre, J R; Poncy, J L

    2010-10-01

    The aim of this study is to propose a single modeling structure to describe both plutonium and americium decorporation by DTPA, which is based on hypotheses mostly validated by experimental data. Decorporation efficacy of extracellular retention depends on the concentration ratio of DTPA vs. actinides and varies in each compartment according to the amount of biological ligands and their affinity for actinides. By contrast, because the relatively long residence time of DTPA after its cell internalization and the stability of actinide-DTPA complexes, intracellular decorporation efficacy is mainly controlled by a DTPA/actinide ratio, which is specific to each retention compartment. Although the affinity of DTPA is much lower for americium than for plutonium, a larger decorporation of americium can be obtained, which is explained by different biological ligands and/or their affinity for the actinide. Altogether, these results show that the relative contribution of intra vs. extracellular decorporation varies depending on the actinide, the chemical form of radionuclides, the galenic formulation of DTPA, and the treatment schedule.

  9. Enhanced ionization efficiency in TIMS analyses of plutonium and americium using porous ion emitters

    DOE PAGES

    Baruzzini, Matthew L.; Hall, Howard L.; Watrous, Matthew G.; ...

    2016-12-05

    Investigations of enhanced sample utilization in thermal ionization mass spectrometry (TIMS) using porous ion emitter (PIE) techniques for the analyses of trace quantities of americium and plutonium were performed. Repeat ionization efficiency (i.e., the ratio of ions detected to atoms loaded on the filament) measurements were conducted on sample sizes ranging from 10–100 pg for americium and 1–100 pg for plutonium using PIE and traditional (i.e., a single, zone-refined rhenium, flat filament ribbon with a carbon ionization enhancer) TIMS filament sources. When compared to traditional filaments, PIEs exhibited an average boost in ionization efficiency of ~550% for plutonium and ~1100%more » for americium. A maximum average efficiency of 1.09% was observed at a 1 pg plutonium sample loading using PIEs. Supplementary trials were conducted using newly developed platinum PIEs to analyze 10 pg mass loadings of plutonium. As a result, platinum PIEs exhibited an additional ~134% boost in ion yield over standard PIEs and ~736% over traditional filaments at the same sample loading level.« less

  10. Solid-liquid separation of oxidized americium from fission product lanthanides

    NASA Astrophysics Data System (ADS)

    Shehee, T. C.; Martin, L. R.; Nash, K. L.

    2010-03-01

    The separation of americium from the lanthanides and curium is a requirement if transmutation of americium is to be performed in advanced nuclear fuel cycles. Oxidation of Am3+ to AmO2+ or AmO22+ may allow separation of Am from Ln and Cm in one step, since the lanthanides and curium do not have higher oxidation states as accessible. Two possible solid-liquid separation methods have been developed to address this difficult separation. Under acidic conditions using oxone or persulfate, the oxidation and retention of tracer Am in the aqueous phase has been observed with a separation factor of 11 ± 1. Most of these studies have been conducted using 237NpO2(NO3), 233UO2(NO3)2, 238Pu(NO3)4 and 241Am(NO3)3 at radiotracer concentrations. Lanthanides precipitate as the sodium or potassium europium double sulfate salt. Under basic conditions, ozone oxidation of Am(CO3)OH(s) solubilizes Am from a lanthanide carbonate hydroxide solid phase to the aqueous phase as the AmO2(CO3)34-or AmO2(CO3)35- species. For the ozone oxidation of the americium tracer a separation factor of 1.6 ± 0.8 and 47 ± 2 for the oxidation/separation in Na2CO3 and NaHCO3 respectively.

  11. Influence of dissolved organic substances in groundwater on sorption behavior of americium and neptunium

    SciTech Connect

    Boggs, S. Jr.; Seitz, M.G.

    1984-01-01

    Groundwaters typically contain dissolved organic carbon consisting largely of high molecular weight compounds of humic and fulvic acids. To evaluate whether these dissolved organic substances can enhance the tranport of radionuclides through the groundwater system, experiments were conducted to examine the sorption of americium and neptunium onto crushed basalt in the presence of dissolved humic- and fulvic-acid organic carbon introduced into synthetic groundwater. The partitioning experiments with synthetic groundwater show that increasing the concentration of either humic or fulvic acid in the water has a significant inhibiting effect on sorption of both americium and neptunium. At 22/sup 0/C, adsorption of these radionuclides, as measured by distribution ratios (the ratio of nuclide sorbed onto the solid to nuclide in solution at the end of the experiment), decreased by 25% to 50% by addition of as little as 1 mg/L dissolved organic carbon and by one to two orders of magnitude by addition of 100 to 200 mg/L dissolved organic carbon. Distribution ratios measured in solutions reacted at 90/sup 0/C similarly decreased with the addition of dissolved organic carbon but generally ranged from one to two orders of magnitude higher than those determined in the 22/sup 0/C experiment. These results suggest that organic carbon dissolved in deep groundwaters may significantly enhance the mobility of radionuclides of americium and neptunium. 23 references, 5 figures, 11 tables.

  12. Fabrication of uranium-americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    NASA Astrophysics Data System (ADS)

    Remy, E.; Picart, S.; Delahaye, T.; Jobelin, I.; Lebreton, F.; Horlait, D.; Bisel, I.; Blanchart, P.; Ayral, A.

    2014-10-01

    Mixed uranium-americium oxides are one of the materials envisaged for Americium Bearing Blankets dedicated to transmutation in fast neutron reactors. Recently, several processes have been developed in order to validate fabrication flowchart in terms of material specifications such as density and homogeneity but also to suggest simplifications for lowering industrial costs and hazards linked to dust generation of highly contaminating and irradiating compounds. This study deals with the application of an innovative route using mixed oxide microspheres obtained from metal loaded resin bead calcination, called Calcined Resin Microsphere Pelletization (CRMP). The synthesis of mixed oxide microsphere precursor of U0.9Am0.1O2±δ is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U0.9Am0.1O2±δ. The ceramic obtained was characterised and results showed that its microstructure is dense and homogeneous and its density attains 95% of the theoretical density. This study validates the scientific feasibility of the CRMP process applied to the fabrication of uranium and americium-containing materials.

  13. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    SciTech Connect

    Degueldre, Claude Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O₂ lattice in an irradiated (60 MW d kg⁻¹) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (~0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am³⁺ species within an [AmO₈]¹³⁻ coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix. - Graphical abstract: Americium LIII XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 μm×300 μm beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO₂ matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: • Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. • The americium redox state as determined from XAS data of irradiated fuel material was Am(III). • In the sample, the Am³⁺ face an AmO₈¹³⁻coordination environment in the (Pu,U)O₂ matrix. • The americium dioxide is reduced by the uranium dioxide matrix.

  14. Americium, plutonium and uranium contamination and speciation in well waters, streams and atomic lakes in the Sarzhal region of the Semipalatinsk Nuclear Test Site, Kazakhstan.

    PubMed

    León Vintró, L; Mitchell, P I; Omarova, A; Burkitbayev, M; Jiménez Nápoles, H; Priest, N D

    2009-04-01

    New data are reported on the concentrations, isotopic composition and speciation of americium, plutonium and uranium in surface and ground waters in the Sarzhal region of the Semipalatinsk Test Site, and an adjacent area including the settlement of Sarzhal. The data relate to filtered water and suspended particulate from (a) streams originating in the Degelen Mountains, (b) the Tel'kem 1 and Tel'kem 2 atomic craters, and (c) wells on farms located within the study area and at Sarzhal. The measurements show that (241)Am, (239,240)Pu and (238)U concentrations in well waters within the study area are in the range 0.04-87mBq dm(-3), 0.7-99mBq dm(-3), and 74-213mBq dm(-3), respectively, and for (241)Am and (239,240)Pu are elevated above the levels expected solely on the basis of global fallout. Concentrations in streams sourced in the Degelen Mountains are similar, while concentrations in the two water-filled atomic craters are somewhat higher. Suspended particulate concentrations in well waters vary considerably, though median values are very low, at 0.01mBq dm(-3), 0.08mBq dm(-3) and 0.32mBq dm(-3) for (241)Am, (239,240)Pu and (238)U, respectively. The (235)U/(238)U isotopic ratio in almost all well and stream waters is slightly elevated above the 'best estimate' value for natural uranium worldwide, suggesting that some of the uranium in these waters is of test-site provenance. Redox analysis shows that on average most of the plutonium present in the microfiltered fraction of these waters is in a chemically reduced form (mean 69%; 95% confidence interval 53-85%). In the case of the atomic craters, the proportion is even higher. As expected, all of the americium present appears to be in a reduced form. Calculations suggest that annual committed effective doses to individual adults arising from the daily ingestion of these well waters are in the range 11-42microSv (mean 21microSv). Presently, the ground water feeding these wells would not appear to be contaminated with

  15. Speciation of americium in seawater and accumulation in the marine sponge Aplysina cavernicola.

    PubMed

    Maloubier, Melody; Michel, Hervé; Solari, Pier Lorenzo; Moisy, Philippe; Tribalat, Marie-Aude; Oberhaensli, François R; Dechraoui Bottein, Marie Yasmine; Thomas, Olivier P; Monfort, Marguerite; Moulin, Christophe; Den Auwer, Christophe

    2015-12-21

    The fate of radionuclides in the environment is a cause of great concern for modern society, seen especially in 2011 after the Fukushima accident. Among the environmental compartments, seawater covers most of the earth's surface and may be directly or indirectly impacted. The interaction between radionuclides and the marine compartment is therefore essential for better understanding the transfer mechanisms from the hydrosphere to the biosphere. This information allows for the evaluation of the impact on humans via our interaction with the biotope that has been largely undocumented up to now. In this report, we attempt to make a link between the speciation of heavy elements in natural seawater and their uptake by a model marine organism. More specifically, because the interaction of actinides with marine invertebrates has been poorly studied, the accumulation in a representative member of the Mediterranean coralligenous habitat, the sponge Aplysina cavernicola, was investigated and its uptake curve exposed to a radiotracer (241)Am was estimated using a high-purity Ge gamma spectrometer. But in order to go beyond the phenomenological accumulation rate, the speciation of americium(III) in seawater must be assessed. The speciation of (241)Am (and natural europium as its chemically stable surrogate) in seawater was determined using a combination of different techniques: Time-Resolved Laser-Induced Fluorescence (TRLIF), Extended X-ray Absorption Fine Structure (EXAFS) at the LIII edge, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and the resulting data were compared with the speciation modeling. In seawater, the americium(III) complex (as well as the corresponding europium complex, although with conformational differences) was identified as a ternary sodium biscarbonato complex, whose formula can be tentatively written as NaAm(CO3)2·nH2O. It is therefore this chemical form of americium that is

  16. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids.

    PubMed

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-10-01

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater-bentonite-fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L(-1)) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10(-10) M (241)Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (k(f)) of 0.01-0.02 h(-1). Am recoveries in each column were 55-60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h(-1) in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. Our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long distance scales because

  17. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

    SciTech Connect

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-07-13

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater–bentonite–fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L–1) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10–10 M241Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (kf) of 0.01–0.02 h–1. Am recoveries in each column were 55–60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h–1 in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. As a result, our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill

  18. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

    DOE PAGES

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; ...

    2015-07-13

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater–bentonite–fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. Themore » colloidal suspension (100 mg L–1) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10–10 M241Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (kf) of 0.01–0.02 h–1. Am recoveries in each column were 55–60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h–1 in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. As a result, our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long

  19. Separation of Americium from Europium using Camphor-BisTriazinyl Pyridine: A Fundamental Study

    SciTech Connect

    Tevepaugh, Kayron N.; Carrick, Jesse D.; Tai, Serene; Coonce, Janet G.; Delmau, Lætitia H.; Ensor, Dale D.

    2015-10-27

    Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. We achieved selective extraction of americium from acidic solution (up to 2M HNO3) containing tenth molar quantities of lanthanides using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Our results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented.

  20. Separation of Americium from Europium using Camphor-BisTriazinyl Pyridine: A Fundamental Study

    DOE PAGES

    Tevepaugh, Kayron N.; Carrick, Jesse D.; Tai, Serene; ...

    2015-10-27

    Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. We achieved selective extraction of americium from acidic solution (up to 2M HNO3) containing tenth molar quantities of lanthanides using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Our results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented.

  1. Magnetic Polarization of the Americium J =0 Ground State in AmFe2

    NASA Astrophysics Data System (ADS)

    Magnani, N.; Caciuffo, R.; Wilhelm, F.; Colineau, E.; Eloirdi, R.; Griveau, J.-C.; Rusz, J.; Oppeneer, P. M.; Rogalev, A.; Lander, G. H.

    2015-03-01

    Trivalent americium has a nonmagnetic (J =0 ) ground state arising from the cancellation of the orbital and spin moments. However, magnetism can be induced by a large molecular field if Am3 + is embedded in a ferromagnetic matrix. Using the technique of x-ray magnetic circular dichroism, we show that this is the case in AmFe2 . Since ⟨Jz⟩=0 , the spin component is exactly twice as large as the orbital one, the total Am moment is opposite to that of Fe, and the magnetic dipole operator ⟨Tz⟩ can be determined directly; we discuss the progression of the latter across the actinide series.

  2. Synergistic extraction of europium and americium into nitrobenzene by using hydrogen dicarbollylcobaltate and dodecaethylene glycol.

    PubMed

    Makrlík, Emanuel; Vaňura, Petr; Selucký, Pavel

    2013-01-01

    Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of dodecaethylene glycol (DDEG, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, H2L2+, ML3+ and MH-1L2+ (M3+ = Eu3+, Am3+; L = DDEG) are extracted into the organic phase. The values of extraction and stability constants of the complex species in nitrobenzene saturated with water have been determined. It was found that in this nitrobenzene medium, the stability constant of the EuL3+ complex is comparable with that of AmL3+.

  3. Comparison of acid leachate and fusion methods to determine plutonium and americium in environmental samples

    SciTech Connect

    Smith, L.L.; Markun, F.; TenKate, T.

    1992-06-01

    The Analytical Chemistry Laboratory at Argonne National Laboratory performs radiochemical analyses for a wide variety of sites within the Department of Energy complex. Since the chemical history of the samples may vary drastically from site to site, the effectiveness of any analytical technique may also vary. This study compares a potassium fluoride-pyrosulfate fusion technique with an acid leachate method. Both normal and high-fired soils and vegetation samples were analyzed for both americium and plutonium. Results show both methods work well, except for plutonium in high-fired soils. Here the fusion method provides higher accuracy.

  4. Americium/europium separation by synergistic extraction mixtures of bis-tetrazolyl pyridines with chlorinated cobalt dicarbollide

    SciTech Connect

    Smirnov, I.V.; Babain, V.A.; Chirkov, A.V.

    2008-07-01

    Americium and europium extraction by synergistic mixtures of 2,6-bis(1-aryl-1 H-tetrazol-5-yl)pyridines (ATP) with chlorinated cobalt dicarbollide (CCD) in polar diluents from acidic media was studied. The effect of diluent, composition of aqueous phase, and substituent nature in the aryl ring of ATPs on the extraction efficiency and selectivity of americium and europium separation was investigated. The Am-Eu separation factor was close to 100 at the optimal ratio of ATPs:CCD {approx}1:1 in the synergistic mixture. High resistance of 2,6-bis-aryl-tetrazolyl pyridines to the action of acids and radiolysis was demonstrated. (authors)

  5. Human bones obtained from routine joint replacement surgery as a tool for studies of plutonium, americium and ⁹⁰Sr body-burden in general public.

    PubMed

    Mietelski, Jerzy W; Golec, Edward B; Tomankiewicz, Ewa; Golec, Joanna; Nowak, Sebastian; Szczygiel, Elżbieta; Brudecki, Kamil

    2011-06-01

    The paper presents a new sampling method for studying in-body radioactive contamination by bone-seeking radionuclides such as (90)Sr, (239+240)Pu, (238)Pu, (241)Am and selected gamma-emitters, in human bones. The presented results were obtained for samples retrieved from routine surgeries, namely knee or hip joints replacements with implants, performed on individuals from Southern Poland. This allowed to collect representative sets of general public samples. The applied analytical radiochemical procedure for bone matrix is described in details. Due to low concentrations of (238)Pu the ratio of Pu isotopes which might be used for Pu source identification is obtained only as upper limits other then global fallout (for example Chernobyl) origin of Pu. Calculated concentrations of radioisotopes are comparable to the existing data from post-mortem studies on human bones retrieved from autopsy or exhumations. Human bones removed during knee or hip joint surgery provide a simple and ethical way for obtaining samples for plutonium, americium and (90)Sr in-body contamination studies in general public. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Isotopic distributions, element ratios, and element mass fractions from enrichment-meter-type gamma-ray measurements of MOX

    SciTech Connect

    Close, D.A.; Parker, J.L.; Haycock, D.L. ); Dragnev, T. )

    1991-01-01

    The gamma-ray spectra from infinitely'' thick mixed oxide samples have been measured. The plutonium isotopics, the U/Pu ratio, the high-Z mass fractions (assuming only plutonium, uranium, and americium), and the low-Z mass fraction (assuming the matrix is only oxygen) can be determined by carefully analyzing the data. The results agree well with the chemical determination of these parameters. 8 refs., 3 figs., 3 tabs.

  7. Penetration and decontamination of americium-241 ex vivo using fresh and frozen pig skin.

    PubMed

    Tazrart, A; Bolzinger, M A; Moureau, A; Molina, T; Coudert, S; Angulo, J F; Briancon, S; Griffiths, N M

    2017-04-01

    Skin contamination is one of the most probable risks following major nuclear or radiological incidents. However, accidents involving skin contamination with radionuclides may occur in the nuclear industry, in research laboratories and in nuclear medicine departments. This work aims to measure the penetration of the radiological contaminant Americium ((241)Am) in fresh and frozen skin and to evaluate the distribution of the contamination in the skin. Decontamination tests were performed using water, Fuller's earth and diethylene triamine pentaacetic acid (DTPA), which is the recommended treatment in case of skin contamination with actinides such as plutonium or americium. To assess these parameters, we used the Franz cell diffusion system with full-thickness skin obtained from pigs' ears, representative of human skin. Solutions of (241)Am were deposited on the skin samples. The radioactivity content in each compartment and skin layers was measured after 24 h by liquid scintillation counting and alpha spectrophotometry. The Am cutaneous penetration to the receiver compartment is almost negligible in fresh and frozen skin. Multiple washings with water and DTPA recovered about 90% of the initial activity. The rest remains fixed mainly in the stratum corneum. Traces of activity were detected within the epidermis and dermis which is fixed and not accessible to the decontamination. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Solvent Extraction Separation of Trivalent Americium from Curium and the Lanthanides

    SciTech Connect

    Jensen, Mark P.; Chiarizia, Renato; Ulicki, Joseph S.; Spindler, Brian D.; Murphy, Daniel J.; Hossain, M; Roca-Sabio, Adrian; de Blas, Andres; Rodriguez-Blas, Teresa

    2015-01-01

    The sterically constrained, macrocyclic, aqueous soluble ligand N,N′-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H2BP18C6) was investigated for separating americium from curium and all the lanthanides by solvent extraction. Pairing H2BP18C6, which favors complexation of larger f-element cations, with acidic organophosphorus extractants that favor extraction of smaller f-element cations, such as bis-(2-ethylhexyl)phosphoric acid (HDEHP) or (2-ethylhexyl)phosphonic acid mono(2-ethylhexyl) ester (HEH[EHP]), created solvent extraction systems with good Cm/Am selectivity, excellent trans-lanthanide selectivity (Kex,Lu/Kex,La = 108), but poor selectivity for Am against the lightest lanthanides. However, using an organic phase containing both a neutral extractant, N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (TEHDGA), and HEH[EHP] enabled rejection of the lightest lanthanides during loading of the organic phase from aqueous nitric acid, eliminating their interference in the americium stripping stages. In addition, although it is a macrocyclic ligand, H2BP18C6 does not significantly impede the mass transfer kinetics of the HDEHP solvent extraction system

  9. Comparative skeletal distribution of americium and plutonium in man, monkey and baboon

    SciTech Connect

    Lynch, T.P.; Dagle, G.E.; Kathren, R.L.; McInroy, J.F.

    1988-10-01

    The skeletal distributions of americium and plutonium in four humans were compared with the skeletal distributions of these radioelements in baboons and monkeys. With respect to the skeletal distribution of these elements, excellent agreement was noted among the four human cases; americium data was available for all four cases and plutonium for three. The human case database was thus adequate for comparison with those of other primates. A statistically significant correlation was found between the /sup 241/Am and /sup 239/Pu + /sup 240/Pu skeletal distributions in the humans and those in non-human primates. Trabecular bone had the highest concentrations of /sup 241/Am and /sup 239 +240/Pu in man, baboon, and monkey. Scaling factors are proposed to convert the percentages of skeletal activity in animal bones to the corresponding percentages in the bones of the human skeleton. However, considerable variation was found between the humans and animals in the percentages of the skeletal activity found in the same bone. 12 refs., 7 tabs.

  10. An economic analysis of a light and heavy water moderated reactor synergy: burning americium using recycled uranium

    SciTech Connect

    Wojtaszek, D.; Edwards, G.

    2013-07-01

    An economic analysis is presented for a proposed synergistic system between 2 nuclear utilities, one operating light water reactors (LWR) and another running a fleet of heavy water moderated reactors (HWR). Americium is partitioned from LWR spent nuclear fuel (SNF) to be transmuted in HWRs, with a consequent averted disposal cost to the LWR operator. In return, reprocessed uranium (RU) is supplied to the HWRs in sufficient quantities to support their operation both as power generators and americium burners. Two simplifying assumptions have been made. First, the economic value of RU is a linear function of the cost of fresh natural uranium (NU), and secondly, plutonium recycling for a third utility running a mixed oxide (MOX) fuelled reactor fleet has been already taking place, so that the extra cost of americium recycling is manageable. We conclude that, in order for this scenario to be economically attractive to the LWR operator, the averted disposal cost due to partitioning americium from LWR spent fuel must exceed 214 dollars per kg, comparable to estimates of the permanent disposal cost of the high level waste (HLW) from reprocessing spent LWR fuel. (authors)

  11. Ditopic CMPO-pillar[5]arenes as unique receptors for efficient separation of americium(III) and europium(III).

    PubMed

    Fang, Yuyu; Yuan, Xiangyang; Wu, Lei; Peng, Zhiyong; Feng, Wen; Liu, Ning; Xu, Dingguo; Li, Shoujian; Sengupta, Arijit; Mohapatra, Prasanta K; Yuan, Lihua

    2015-03-11

    A unique host-guest recognition process involving a new class of homoditopic CMPO-pillar[5]arenes and lanthanides was revealed to proceed in a stepwise manner, and correlated with the efficient separation of americium(III) and europium(III) under acidic feed conditions.

  12. EURADOS intercomparison on measurements and Monte Carlo modelling for the assessment of americium in a USTUR leg phantom.

    PubMed

    Lopez, M A; Broggio, D; Capello, K; Cardenas-Mendez, E; El-Faramawy, N; Franck, D; James, A C; Kramer, G H; Lacerenza, G; Lynch, T P; Navarro, J F; Navarro, T; Perez, B; Rühm, W; Tolmachev, S Y; Weitzenegger, E

    2011-03-01

    A collaboration of the EURADOS working group on 'Internal Dosimetry' and the United States Transuranium and Uranium Registries (USTUR) has taken place to carry out an intercomparison on measurements and Monte Carlo modelling determining americium deposited in the bone of a USTUR leg phantom. Preliminary results and conclusions of this intercomparison exercise are presented here.

  13. Isotope ratio analysis of individual sub-micrometer plutonium particles with inductively coupled plasma mass spectrometry.

    PubMed

    Esaka, Fumitaka; Magara, Masaaki; Suzuki, Daisuke; Miyamoto, Yutaka; Lee, Chi-Gyu; Kimura, Takaumi

    2010-12-15

    Information on plutonium isotope ratios in individual particles is of great importance for nuclear safeguards, nuclear forensics and so on. Although secondary ion mass spectrometry (SIMS) is successfully utilized for the analysis of individual uranium particles, the isobaric interference of americium-241 to plutonium-241 makes difficult to obtain accurate isotope ratios in individual plutonium particles. In the present work, an analytical technique by a combination of chemical separation and inductively coupled plasma mass spectrometry (ICP-MS) is developed and applied to isotope ratio analysis of individual sub-micrometer plutonium particles. The ICP-MS results for individual plutonium particles prepared from a standard reference material (NBL SRM-947) indicate that the use of a desolvation system for sample introduction improves the precision of isotope ratios. In addition, the accuracy of the (241)Pu/(239)Pu isotope ratio is much improved, owing to the chemical separation of plutonium and americium. In conclusion, the performance of the proposed ICP-MS technique is sufficient for the analysis of individual plutonium particles.

  14. XRD monitoring of α self-irradiation in uranium-americium mixed oxides.

    PubMed

    Horlait, Denis; Lebreton, Florent; Roussel, Pascal; Delahaye, Thibaud

    2013-12-16

    The structural evolution under (241)Am self-irradiation of U(1-x)Am(x)O(2±δ) transmutation fuels (with x ≤ 0.5) was studied by X-ray diffraction (XRD). Samples first underwent a preliminary heat treatment performed under a reducing atmosphere (Ar/H2(4%)) aiming to recover the previously accumulated structural defects. Over all measurements (carried out over up to a full year and for integrated doses up to 1.5 × 10(18) α-decay events·g(-1)), only fluorite U(1-x)Am(x)O(2±δ) solid solutions were observed. Within a few days after the end of the heat treatment, each of the five studied samples was slowly oxidized as a consequence of their move to air atmosphere, which is evidenced by XRD by an initial sharp decrease of the unit cell parameter. For the compounds with x ≤ 0.15, this oxidation occurred without any phase transitions, but for U0.6Am0.4O(2±δ) and U0.5Am0.5O(2±δ), this process is accompanied by a transition from a first fluorite solid solution to a second oxidized one, as the latter is thermodynamically stable in ambient conditions. In the meantime and after the oxidation process, (241)Am α self-irradiation caused a structural swelling up to ∼0.8 vol %, independently of the sample composition. The kinetic constants of swelling were also determined by regression of experimental data and are, as expected, dependent on x and thus on the dose rate. The normalization of these kinetic constants by sample α-activity, however, leads to very close swelling rates among the samples. Finally, evolutions of microstrain and crystallite size were also monitored, but for the considered dose rates and cumulated doses, α self-irradiation was found, within the limits of the diffractometer used, to have almost no impact on these characteristics. Microstrain was found to be influenced instead by the americium content in the materials (i.e., by the impurities associated with americium starting material and the increase of cationic charge heterogeneity with

  15. Isotopic Biogeochemistry

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  16. Imitators of plutonium and americium in a mixed uranium- plutonium nitride fuel

    NASA Astrophysics Data System (ADS)

    Nikitin, S. N.; Shornikov, D. P.; Tarasov, B. A.; Baranov, V. G.; Burlakova, M. A.

    2016-04-01

    Uranium nitride and mix uranium nitride (U-Pu)N is most popular nuclear fuel for Russian Fast Breeder Reactor. The works in hot cells associated with the radiation exposure of personnel and methodological difficulties. To know the main physical-chemical properties of uranium-plutonium nitride it necessary research to hot cells. In this paper, based on an assessment of physicochemical and thermodynamic properties of selected simulators Pu and Am. Analogues of Pu is are Ce and Y, and analogues Am - Dy. The technique of obtaining a model nitride fuel based on lanthanides nitrides and UN. Hydrogenation-dehydrogenation- nitration method of derived powders nitrides uranium, cerium, yttrium and dysprosium, held their mixing, pressing and sintering, the samples obtained model nitride fuel with plutonium and americium imitation. According to the results of structural studies have shown that all the samples are solid solution nitrides rare earth (REE) elements in UN.

  17. Transportability Class of Americium in K Basin Sludge under Ambient and Hydrothermal Processing Conditions

    SciTech Connect

    Delegard, Calvin H.; Schmitt, Bruce E.; Schmidt, Andrew J.

    2006-08-01

    This report establishes the technical bases for using a ''slow uptake'' instead of a ''moderate uptake'' transportability class for americium-241 (241Am) for the K Basin Sludge Treatment Project (STP) dose consequence analysis. Slow uptake classes are used for most uranium and plutonium oxides. A moderate uptake class has been used in prior STP analyses for 241Am based on the properties of separated 241Am and its associated oxide. However, when 241Am exists as an ingrown progeny (and as a small mass fraction) within plutonium mixtures, it is appropriate to assign transportability factors of the predominant plutonium mixtures (typically slow) to the Am241. It is argued that the transportability factor for 241Am in sludge likewise should be slow because it exists as a small mass fraction as the ingrown progeny within the uranium oxide in sludge. In this report, the transportability class assignment for 241Am is underpinned with radiochemical characterization data on K Basin sludge and with studies conducted with other irradiated fuel exposed to elevated temperatures and conditions similar to the STP. Key findings and conclusions from evaluation of the characterization data and published literature are summarized here. Plutonium and 241Am make up very small fractions of the uranium within the K Basin sludge matrix. Plutonium is present at about 1 atom per 500 atoms of uranium and 241Am at about 1 atom per 19000 of uranium. Plutonium and americium are found to remain with uranium in the solid phase in all of the {approx}60 samples taken and analyzed from various sources of K Basin sludge. The uranium-specific concentrations of plutonium and americium also remain approximately constant over a uranium concentration range (in the dry sludge solids) from 0.2 to 94 wt%, a factor of {approx}460. This invariability demonstrates that 241Am does not partition from the uranium or plutonium fraction for any characterized sludge matrix. Most of the K Basin sludge characterization

  18. Magnetic polarization of the americium J=0 ground state in AmFe(2).

    PubMed

    Magnani, N; Caciuffo, R; Wilhelm, F; Colineau, E; Eloirdi, R; Griveau, J-C; Rusz, J; Oppeneer, P M; Rogalev, A; Lander, G H

    2015-03-06

    Trivalent americium has a nonmagnetic (J=0) ground state arising from the cancellation of the orbital and spin moments. However, magnetism can be induced by a large molecular field if Am^{3+} is embedded in a ferromagnetic matrix. Using the technique of x-ray magnetic circular dichroism, we show that this is the case in AmFe_{2}. Since ⟨J_{z}⟩=0, the spin component is exactly twice as large as the orbital one, the total Am moment is opposite to that of Fe, and the magnetic dipole operator ⟨T_{z}⟩ can be determined directly; we discuss the progression of the latter across the actinide series.

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

    SciTech Connect

    Holden, N.E.

    1985-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Holden, N. E.

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

  1. Evaluation of the readsorption of plutonium and americium in dynamic fractionations of environmental solid samples.

    PubMed

    Petersen, Roongrat; Hou, Xiaolin; Hansen, Elo Harald

    2008-07-01

    A dynamic extraction system exploiting sequential injection (SI) for sequential extractions incorporating a specially designed extraction column is developed to fractionate radionuclides in environmental solid samples such as soils and sediments. The extraction column can contain up to 5 g of a soil sample, and under optimal operational conditions it does not give rise to creation of back pressure. Attention has been placed on studies of the readsorption problems during sequential extraction using a modified Standards, Measurements and Testing (SM&T) scheme with four-step sequential extractions. The degree of readsorption in dynamic and conventional batch extraction systems is compared and evaluated by using a double-spiking technique. A high degree of readsorption of plutonium and americium (>75%) was observed in both systems, and they also exhibited similar distribution patterns of the two radionuclides. However, the dynamic system is fully automated, eliminates manual separations, significantly reduces the operational time required, and offers detailed kinetic information.

  2. The Role of Colloids in the Transport of Plutonium and Americium: Implications for

    SciTech Connect

    Kersting, A B

    2003-09-17

    Colloids are small particulates (ranging in size from 1 to 0.001 micron) composed of inorganic and organic material and found in all natural water. Due to their small size, they have the ability to remain suspended in water and transported. Small amounts of plutonium (Pu) and americium (Am) can adsorb (attach) to colloids, and/or form colloidal-sized polymers and migrate in water. At Rocky Flats Environmental Technology Site (RFETS) sedimentation and resuspension of particulates and colloids in surface waters represent the dominant process for Pu and Am migration. The amount of Pu and Am that can be transported at RFETS has been quantified in the Pathway Analysis Report. The Pathway Analysis Report shows that the two dominant pathways for Pu and Am transport at RFETS are air and surface water. Shallow groundwater and biological pathways are minor.

  3. Isotopic separation

    SciTech Connect

    Chen, C.

    1981-03-10

    Method and apparatus for separating isotopes in an isotopic mixture of atoms or molecules by increasing the mass differential among isotopic species. The mixture containing a particular isotope is selectively irradiated so as to selectively excite the isotope. This preferentially excited species is then reacted rapidly with an additional preselected radiation, an electron or another chemical species so as to form a product containing the specific isotope, but having a mass different than the original species initially containing the particular isotope. The product and the remaining balance of the mixture is then caused to flow through a device which separates the product from the mixture based upon the increased mass differential.

  4. High Purity Americium-241 for Fuel Cycle R&D Program

    SciTech Connect

    Dr. Paul A. Lessing

    2011-07-01

    Previously the U.S. Department of Energy released Am-241 for various applications such as smoke detectors and Am-Be neutron sources for oil wells. At this date there is a shortage of usable, higher purity Am-241 in metal and oxide form available in the United States. Recently, the limited source of Am-241 has been from Russia with production being contracted to existing customers. The shortage has resulted in the price per gram rising dramatically over the last few years. DOE-NE currently has need for high purity Am-241 metal and oxide to fabricate fuel pellets for reactor testing in the Fuel Cycle R&D program. All the available high purity americium has been gathered from within the DOE system of laboratories. However, this is only a fraction of the projected needs of FCRD over the next 10 years. Therefore, FCR&D has proposed extraction and purification concepts to extract Am-241 from a mixed AmO2-PuO2 feedstock stored at the Savannah River Site. The most simple extraction system is based upon high temperature reduction using lanthanum metal with concurrent evaporation and condensation to produce high purity Am metal. Metallic americium has over a four order of magnitude higher vapor pressure than plutonium. Results from small-scale reduction experiments are presented. These results confirm thermodynamic predictions that at 1000 deg C metallic lanthanum reduces both PuO2 and AmO2. Faster kinetics are expected for temperatures up to about 1500 deg C.

  5. Colloid-borne americium migration in Gorleben groundwater: significance of iron secondary phase transformation.

    PubMed

    Schäfer, Thorsten; Artinger, Robert; Dardenne, Kathy; Bauer, Andreas; Schuessler, Wolfram; Kim, Jae Il

    2003-04-15

    The mobility of actinides in natural water may be enhanced by colloid-mediated transport. In this context the reversibility of actinide colloid interaction is a key factor. Iron is an element that can generate colloids under conditions found in natural waters. In this paper, the impact of hematite and the low-crystalline precursor 2-line ferrihydrite on colloid-mediated transport of americium(III) is investigated. Am(III)-containing iron colloids are generated from two different approaches, namely contact between the two in aqueous solution or coprecipitation of Am(III) during iron colloid generation. Dissolved organic carbon (DOC), especially humic substances, has a strong influence on the stability of inorganic colloids. In addition, humic substances interfere in the distribution and kinetics of exchange between groundwater and sediments. Four groundwaters from the Gorleben aquifer system are used with DOC concentrations varying between 0.9 and 81.6 mgC/L together with Pleistocene Aeolian quartz sand from this site. Batch and column experiments are conducted under near-natural conditions (Ar + 1% CO2). To study the influence of kinetics, contact times up to one month are studied. The dynamic light-scattering investigations show that the colloidal stability of the 2-line ferrihydrite increases with increasing DOC concentration. The low-crystalline iron colloids have a marginal influence on the Am(III) transport due to reversibility of americium sorption. Contrary to this, the crystalline hematite generated from coprecipitation of Am(III) leads to an increase of unretarded colloid-mediated Am(III) transport up to a factor of almost five. Chemical characterization of these hematite colloids shows that Am(III) is structurally entrapped in the hematite. The distribution of Am(III) and 2-line ferrihydrite between groundwater and sand sediment remained in disequilibrium even after one month. This shows that the kinetics of Am(III) distribution between the different

  6. Aqueous complexes for efficient size-based separation of americium from curium.

    PubMed

    Jensen, Mark P; Chiarizia, Renato; Shkrob, Ilya A; Ulicki, Joseph S; Spindler, Brian D; Murphy, Daniel J; Hossain, Mahmun; Roca-Sabio, Adrián; Platas-Iglesias, Carlos; de Blas, Andrés; Rodríguez-Blas, Teresa

    2014-06-16

    Complexation of the adjacent actinide ions americium(III) and curium(III) by the ligand N,N'-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H2bp18c6) in aqueous solution was studied to quantify and characterize its americium/curium selectivity. Liquid-liquid extraction and spectrophotometric titration indicated the presence of both fully deprotonated and monoprotonated complexes, An(bp18c6)(+) and An(Hbp18c6)(2+) (An = Am or Cm), at the acidities that would be encountered when treating nuclear wastes. The stability constants of the complexes in 1 M NaNO3 determined using competitive complexation were log β101 = 15.49 ± 0.06 for Am and 14.88 ± 0.03 for Cm, indicating a reversal of the usual order of complex stability, where ligands bind the smaller Cm(III) ion more tightly than Am(III). The Am/Cm selectivity of bp18c6(2-) that is defined by the ratio of the Am and Cm stability constants (β101 Am/β101 Cm = 4.1) is the largest reported so far for binary An(III)-ligand complexes. Theoretical density functional theory calculations using the B3LYP functional suggest that the ligand's size-selectivity for larger 4f- and 5f-element cations arises from steric constraints in the crown ether ring. Enhanced 5f character in molecular orbitals involving actinide-nitrogen interactions is predicted to favor actinide(III) complexation by bp18c6(2-) over the complexation of similarly sized lanthanide(III) cations.

  7. Isotopic abundance measurements on solid nuclear-type samples by glow discharge mass spectrometry.

    PubMed

    Betti, M; Rasmussen, G; Koch, L

    1996-07-01

    A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopic measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern have been determined. Interferences arising from the matrix sample and the discharge gas (Ar) for each of these elements are discussed. The GDMS results are compared with those from Thermal Ionization Mass Spectrometry (TIMS). For boron and lithium at microg/g-ng/g levels, the two methods gave results in good agreement. In samples containing uranium the isotopic composition obtained by GDMS was in agreement with those from TIMS independently of the enrichment. Attempts for the determination of plutonium isotopic composition were also made. In this case, due to the interferences of uranium at mass 238 and americium at mass 241, the GDMS raw data are complementary with those values obtained from physical non-destructive techniques.

  8. Probing the 5f electrons: A relativistic DFT study of americium surfaces

    NASA Astrophysics Data System (ADS)

    Dholabhai, Pratik Pankajkumar

    complex nature of the transuranium actinides. The actinides are also characterized by the increasing prominence of relativistic effects and their study can, in fact, give us an in depth understanding of the role of relativity throughout the periodic table. Among the transuranium actinides, the unique electronic properties of the manmade Americium (Am) metal, which was first successfully synthesized and isolated at the wartime Metallurgical Laboratory, have received increased interests, from both scientific and technological points of view. Am occupies a central position in the actinide series in our understanding of the behavior of the 5f electrons. It is widely believed that the properties and the behavior of the 5f electrons change dramatically starting from somewhere between Pu and Am. As a result, a large number of experimental and theoretical works have been done in recent years to gain insight into the structural and electronic properties of Am. In this work, atomic hydrogen and oxygen, molecular hydrogen and oxygen and water adsorptions on the (0001) surface of double hexagonal closed packed americium have been studied at both non-spin-orbit coupling (NSO) and spin-orbit coupling (SO) using generalized gradient approximation to density functional theory using the Perdew-Burke-Ernzerhof (PBE) formulation for the exchange-correlation functional. For atomic and molecular adsorptions, various chemisorption sites such as, top(t1), bridge(b2) and hcp(h3) have been investigated. Details of energetics of the chemisorption process, such as chemisorption energies, adatom/admolecule separation distances and inter molecular distances will be presented. Magnetic moments are also calculated for bare americium and the chemisorbed system. Adsorption of molecular hydrogen and oxygen and possible dissociative adsorption on americium surface will be presented. The adsorbate-substrate interactions have been analyzed in detail using the partial charges inside the muffin-tin spheres

  9. The behaviour under irradiation of molybdenum matrix for inert matrix fuel containing americium oxide (CerMet concept)

    NASA Astrophysics Data System (ADS)

    D'Agata, E.; Knol, S.; Fedorov, A. V.; Fernandez, A.; Somers, J.; Klaassen, F.

    2015-10-01

    Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors or Accelerator Driven System (ADS, subcritical reactors dedicated to transmutation) of long-lived nuclides like 241Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. In order to safely burn americium in a fast reactor or ADS, it must be incorporated in a matrix that could be metallic (CerMet target) or ceramic (CerCer target). One of the most promising matrix to incorporate Am is molybdenum. In order to address the issues (swelling, stability under irradiation, gas retention and release) of using Mo as matrix to transmute Am, two irradiation experiments have been conducted recently at the High Flux Reactor (HFR) in Petten (The Netherland) namely HELIOS and BODEX. The BODEX experiment is a separate effect test, where the molybdenum behaviour is studied without the presence of fission products using 10B to ;produce; helium, the HELIOS experiment included a more representative fuel target with the presence of Am and fission product. This paper covers the results of Post Irradiation Examination (PIE) of the two irradiation experiments mentioned above where molybdenum behaviour has been deeply investigated as possible matrix to transmute americium (CerMet fuel target). The behaviour of molybdenum looks satisfying at operating temperature but at high temperature (above 1000 °C) more investigation should be performed.

  10. Vertical and horizontal fluxes of plutonium and americium in the western Mediterranean and the Strait of Gibraltar.

    PubMed

    León Vintró, L; Mitchell, P I; Condren, O M; Downes, A B; Papucci, C; Delfanti, R

    1999-09-30

    New data on the vertical distributions of plutonium and americium in the waters of the western Mediterranean and the Strait of Gibraltar are examined in terms of the processes governing their delivery to, transport in and removal from the water column within the basin. Residence times for plutonium and americium in surface waters of approximately 15 and approximately 3 years, respectively, are deduced, and it is shown that by the mid 1990s only approximately 35% of the 239,240Pu and approximately 5% of the 241Am deposited as weapons fallout still resided in the water column. Present 239,240Pu inventories in the water column and the underlying sediments are estimated to be approximately 25 TBq and approximately 40 TBq, respectively, which reconcile well with the time-integrated fallout deposition in this zone, taken to be approximately 69 TBq. The data show that there are significant net outward fluxes of plutonium and americium from the basin through the Strait of Gibraltar at the present time. These appear to be compensated by net inward fluxes of similar magnitude through the Strait of Sicily. Thus, the time-integrated fallout deposition in the western basin can be accounted for satisfactorily in terms of present water column and sediment inventories. Enhanced scavenging on the continental shelves, as evidenced by the appreciably higher transuranic concentrations in shelf sediments, supports this contention.

  11. Soil-plant transfer of plutonium and americium in contaminated regions of Belarus after the Chernobyl catastrophe.

    PubMed

    Sokolik, G A; Ovsiannikova, S V; Ivanova, T G; Leinova, S L

    2004-09-01

    Experimental data are presented for the soil to plant transfer of plutonium and americium into the main species of grass vegetation of Belarusian grasslands contaminated as a result of the Chernobyl catastrophe of 1986. The content of radionuclides in pore soil solutions and the total reserve of biologically available forms of plutonium and americium in rooting layers of different soil varieties have been established. The distribution coefficients of (239,240)Pu and 241Am between the solid phase and pore waters of soils have been evaluated. The migration ability and biological availability of radionuclides in soils with different structures of the absorbing complex have been analyzed for various landscape conditions. The dependence of soil to plant transfer of plutonium and americium on the content and composition of organic matter, and other characteristics of the soil complex has been studied. On the basis of these data, predictions of the contamination levels of the main grass species of natural and agricultural ecosystems by 241Am are presented.

  12. Americium and plutonium in water, biota, and sediment from the central Oregon coast

    SciTech Connect

    Nielsen, Reinald Dreas

    1982-06-01

    Plutonium-239, 240 and americium-241 were measured in the mussel Mytilus californianus from the region of Coos Bay, OR. The flesh of this species has a plutonium concentration of about 90 fCi/kg, and an Am-241/Pu-239, 240 ratio that is high relative to mixed fallout, ranging between two and three. Transuranic concentrations in sediment, unfiltered water, and filterable particulates were also measured; none of these materials has an Am/Pu ratio as greatly elevated as the mussels, and there is no apparent difference in the Am/Pu ratio of terrestrial runoff and coastal water. Sediment core profiles do not allow accumulation rates or depositional histories to be identified, but it does not appear that material characterized by a high Am/Pu ratio has ever been introduced to this estuary. Other bivalves (Tresus capax and Macoma nasuta) and a polychaete (Abarenicola sp.) do not have an elevated Am/Pu ratio, although the absolute activity of plutonium in the infaunal bivalves is roughly four times that in the mussels.

  13. In Vitro Dissolution Tests of Plutonium and Americium Containing Contamination Originating From ZPPR Fuel Plates

    SciTech Connect

    William F. Bauer; Brian K. Schuetz; Gary M. Huestis; Thomas B. Lints; Brian K. Harris; R. Duane Ball; Gracy Elias

    2012-09-01

    Assessing the extent of internal dose is of concern whenever workers are exposed to airborne radionuclides or other contaminants. Internal dose determinations depend upon a reasonable estimate of the expected biological half-life of the contaminants in the respiratory tract. One issue with refractory elements is determining the dissolution rate of the element. Actinides such as plutonium (Pu) and Americium (Am) tend to be very refractory and can have biological half-lives of tens of years. In the event of an exposure, the dissolution rates of the radionuclides of interest needs to be assessed in order to assign the proper internal dose estimates. During the November 2011 incident at the Idaho National Laboratory (INL) involving a ZPPR fuel plate, air filters in a constant air monitor (CAM) and a giraffe filter apparatus captured airborne particulate matter. These filters were used in dissolution rate experiments to determine the apparent dissolution half-life of Pu and Am in simulated biological fluids. This report describes these experiments and the results. The dissolution rates were found to follow a three term exponential decay equation. Differences were noted depending upon the nature of the biological fluid simulant. Overall, greater than 95% of the Pu and 93% of the Am were in a very slow dissolving component with dissolution half-lives of over 10 years.

  14. Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site.

    PubMed

    Ikeda-Ohno, Atsushi; Harrison, Jennifer J; Thiruvoth, Sangeeth; Wilsher, Kerry; Wong, Henri K Y; Johansen, Mathew P; Waite, T David; Payne, Timothy E

    2014-09-02

    During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed.

  15. Preparation of curium-americium oxide microspheres by resin-bead loading

    SciTech Connect

    Chattin, F.R.; Benker, D.E.; Lloyd, M.H.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1980-01-01

    Resin-bead loading and calcination techniques have been used to produce all curium and americium oxide feed material (about 2.2 kg) for HFIR targets since 1971. The process based on Dowex 50W resin has progressed from a series of test runs, through special production runs, into routine production in permanent equipment beginning in 1975. Key attributes of this process are its reliability, high yields, and ease of operation. The process is suited for remote operation in hot cells. Yields approaching 95% are routinely obtained and only one unacceptable product has been generated during routine production operations. There have been no problems in fabricating targets from this oxide or in the subsequent irradiation of these targets. The present scale of production of 150 to 250 g/y supplies the present need and is comparable with the level of other chemical process operations at TRU. Since the annual production is accomplished in two 8 to 12 day periods, there has been no reason to consider further scale-up. However, the rate of production could easily be doubled by simply adding a second set of calcination equipment.

  16. Development and Testing of an Americium/Lanthanide Separation Flowsheet Using Sodium Bismuthate

    SciTech Connect

    Jack Law; Bruce Mincher; Troy Garn; Mitchell Greenhalgh; Nicholas Schmitt; Veronica Rutledge

    2014-04-01

    The separation of Am from the lanthanides and curium is a key step in proposed advanced fuel cycle scenarios. The partitioning and transmutation of Am is desirable to minimize the long-term heat load of material interred in a future high-level waste repository. A separation process amenable to process scale-up remains elusive. Given only subtle chemistry differences within and between the ions of the trivalent actinide and lanthanide series this separation is challenging ; however, higher oxidation states of americium can be prepared using sodium bismuthate and separated via solvent extraction using diamylamylphosphonate (DAAP) extraction. Among the other trivalent metals only Ce is also oxidized and extracted. Due to the long-term instability of Am(VI) , the loaded organic phase is readily selectively stripped to partition the actinide to a new acidic aqueous phase. Batch extraction distribution ratio measurements were used to design a flowsheet to accomplish this separation. Additionally, crossflow filtration was investigated as a method to filter the bismuthate solids from the feed solution prior to extraction. Results of the filtration studies, flowsheet development work and flowsheet performance testing using a centrifugal contactor are detailed.

  17. Americium and curium total half-lives and for the spontaneous fission branch

    SciTech Connect

    Holden, N.E.

    1985-01-01

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

  18. Americium and trivalent Lanthanides incorporation in high-level waste glass-ceramics

    NASA Astrophysics Data System (ADS)

    Bardez-Giboire, Isabelle; Kidari, Abdessamad; Magnin, Magali; Dussossoy, Jean-Luc; Peuget, Sylvain; Caraballo, Richard; Tribet, Magaly; Doreau, Franck; Jégou, Christophe

    2017-08-01

    The incorporation and partitioning of americium and trivalent lanthanides were investigated in aluminoborosilicate glass-ceramics with apatite-like silicate crystals of general formula Ca2(Ln,Am)8(SiO4)6O2. A microstructural and structural study of two glass-ceramics containing Am2O3 - La2O3 or Nd2O3 - La2O3, respectively, was carried out by XRD, SEM/EDS and EMPA so as to assess a comparison of Lanthanides and Actinides partitioning into apatite crystals and residual glass. Moreover, Raman analyses of residual glasses were performed to compare the role of Am and Nd on the glassy structure. Results put forward that shape, composition, Ln/Am stoichiometry and cell parameters of apatite crystals of both (Am-La) and (Nd-La) glass-ceramics are very close. This paper thus shows similar results for (Am-La) and (Nd-La) glass-ceramics in terms of apatite/glass partitioning and in terms of structural role on glassy structure. It can be therefore put forward that Nd3+ and Am3+ behaviors are close, either in the glass or in the crystalline structure.

  19. Characterization of neutron calibration fields at the TINT's 50 Ci americium-241/beryllium neutron irradiator

    NASA Astrophysics Data System (ADS)

    Liamsuwan, T.; Channuie, J.; Ratanatongchai, W.

    2015-05-01

    Reliable measurement of neutron radiation is important for monitoring and protection in workplace where neutrons are present. Although Thailand has been familiar with applications of neutron sources and neutron beams for many decades, there is no calibration facility dedicated to neutron measuring devices available in the country. Recently, Thailand Institute of Nuclear Technology (TINT) has set up a multi-purpose irradiation facility equipped with a 50 Ci americium-241/beryllium neutron irradiator. The facility is planned to be used for research, nuclear analytical techniques and, among other applications, calibration of neutron measuring devices. In this work, the neutron calibration fields were investigated in terms of neutron energy spectra and dose equivalent rates using Monte Carlo simulations, an in-house developed neutron spectrometer and commercial survey meters. The characterized neutron fields can generate neutron dose equivalent rates ranging from 156 μSv/h to 3.5 mSv/h with nearly 100% of dose contributed by neutrons of energies larger than 0.01 MeV. The gamma contamination was less than 4.2-7.5% depending on the irradiation configuration. It is possible to use the described neutron fields for calibration test and routine quality assurance of neutron dose rate meters and passive dosemeters commonly used in radiation protection dosimetry.

  20. Americium-based oxides: Dense pellet fabrication from co-converted oxalates

    NASA Astrophysics Data System (ADS)

    Horlait, Denis; Lebreton, Florent; Gauthé, Aurélie; Caisso, Marie; Arab-Chapelet, Bénédicte; Picart, Sébastien; Delahaye, Thibaud

    2014-01-01

    Mixed oxides are used as nuclear fuels and are notably envisaged for future fuel cycles including plutonium and minor actinide recycling. In this context, processes are being developed for the fabrication of uranium-americium mixed-oxide compounds for transmutation. The purpose of these processes is not only the compliance with fuel specifications in terms of density and homogeneity, but also the simplification of the process for its industrialization as well as lowering dust generation. In this paper, the use of a U0.85Am0.15O2±δ powder synthesized by oxalate co-conversion as a precursor for dense fuel fabrications is assessed. This study notably focuses on sintering, which yielded pellets up to 96% of the theoretical density, taking advantage of the high reactivity and homogeneity of the powder. As-obtained pellets were further characterized to be compared to those obtained via processes based on the UMACS (Uranium Minor Actinide Conventional Sintering) process. This comparison highlights several advantages of co-converted powder as a precursor for simplified processes that generate little dust.

  1. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    NASA Astrophysics Data System (ADS)

    Degueldre, Claude; Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg-1) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (˜0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13- coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix.

  2. Assessment of radiation doses from residential smoke detectors that contain americium-241

    SciTech Connect

    O'Donnell, F.R.; Etnier, E.L.; Holton, G.A.; Travis, C.C.

    1981-10-01

    External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq (3 ..mu..Ci) americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv (0.4 prem) to 20 nSv (2 ..mu..rem) for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 ..mu..Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 ..mu..Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft/sup 2/).

  3. Isotope separation

    DOEpatents

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  4. Vitrification of F-area americium/curium: feasibility study and preliminary process recommendation

    SciTech Connect

    Ramsey, W.G.; Miller, D.; Minichan, R.; Coleman, L.; Schumacher, R.; Hardy, B.; Jones, R.

    1994-04-29

    Work was performed to identify a process to vitrify the contents of F- canyon Tank 17.1. Tank 17.1 contains the majority of americium (Am) and curium (Cm) contained in the DOE Complex. Oak Ridge National Laboratory (ORNL) has made a formal request for this material as fuel for production of Cf252 and other transplutonium actinides. The Am and Cm (and associated lanthanide fission products) are currently in nitric acid solution. Transportation of the intensely radioactive Am/Cm in liquid form is not considered possible. As a result, the material will either be solidified and shipped to ORNL or discarded to the Tank Farm. Nuclear Materials Processing Technology (NMPT), therefore, requested Defense Waste Processing Technology (DWPT) to determine if the Tank 17.1 material could be vitrified, and if it was vitrified could the americium and curium be successfully recovered. Research was performed to determine if the Tank 17.1 contents could indeed be mixed with glass formers and vitrified. Additional studies identified critical process parameters such as heat loading, melter requirements, off-gas evolution, etc. Discussions with NMPT personnel were initiated to determine existing facilities where this work could be accomplished safely. A process has been identified which will convert the Am/Cm material into approximately 300kg of glass. This will be done by initially removing the large quantities of transition metals and aluminum. Oxalic acid will be added to Tank 17.1 and the actinides and lanthanides will be precipitated as oxalates. The remaining aqueous fraction will be removed and the lanthanides and actinides will then be redissolved. The solution will be evaporated and steam stripped down to approximately 100g/I solids and 1N nitric acid prior to being transferred into a receipt/feed tank in the Multi- Purpose Processing Facility (MPPF - formerly Section 18 of F-Canyon). The Am/Cm solution will then be fed directly into a bushing melter. Glass beads will be added

  5. EFFECT OF COMPOSITION OF SELECTED GROUNDWATERS FROM THE BASIN AND RANGE PROVINCE ON PLUTONIUM, NEPTUNIUM, AND AMERICIUM SPECIATION.

    USGS Publications Warehouse

    Rees, Terry F.; Cleveland, Jess M.; Nash, Kenneth L.

    1984-01-01

    The speciation of plutonium, neptunium, and americium was determined in groundwaters from four sources in the Basin and Range Province: the lower carbonate aquifer, Nevada Test Site (NTS) (Crystal Pool); alluvial fill, Frenchman Flat, NTS (well 5C); Hualapai Valley, Arizona (Red Lake south well); and Tularosa Basin, New Mexico (Rentfrow well). The results were interpreted to indicate that plutonium and, to a lesser extent, neptunium are least soluble in reducing groundwaters containing a large concentration of sulfate ion and a small concentration of strongly complexing anions. The results further emphasize the desirability of including studies such as this among the other site-selection criteria for nuclear waste repositories.

  6. Americium/Lanthanide Separations in Alkaline Solutions for Advanced Nuclear Fuel Cycles

    SciTech Connect

    Goff, George S.; Long, Kristy Marie; Reilly, Sean D.; Jarvinen, Gordon D.; Runde, Wolfgang H.

    2012-06-11

    Project goals: Can used nuclear fuel be partitioned by dissolution in alkaline aqueous solution to give a solution of uranium, neptunium, plutonium, americium and curium and a filterable solid containing nearly all of the lanthanide fission products and certain other fission products? What is the chemistry of Am/Cm/Ln in oxidative carbonate solutions? Can higher oxidation states of Am be stabilized and exploited? Conclusions: Am(VI) is kinetically stable in 0.5-2.0 M carbonate solutions for hours. Aliquat 336 in toluene has been successfully shown to extract U(VI) and Pu(VI) from carbonate solutions. (Stepanov et al 2011). Higher carbonate concentration gives lower D, SF{sub U/Eu} for = 4 in 1 M K{sub 2}CO{sub 3}. Experiments with Am(VI) were unsuccessful due to reduction by the organics. Multiple sources of reducing organics...more optimization. Reduction experiments of Am(VI) in dodecane/octanol/Aliquat 336 show that after 5 minutes of contact, only 30-40% of the Am(VI) has been reduced. Long enough to perform an extraction. Shorter contact times, lower T, and lower Aliquat 336 concentration still did not result in any significant extraction of Am. Anion exchange experiments using a strong base anion exchanger show uptake of U(VI) with minimal uptake of Nd(III). Experiments with Am(VI) indicate Am sorption with a Kd of 9 (10 minute contact) but sorption mechanism is not yet understood. SF{sub U/Nd} for = 7 and SF{sub U/Eu} for = 19 after 24 hours in 1 M K{sub 2}CO{sub 3}.

  7. Sintering trials of analogues of americium oxides for radioisotope power systems

    NASA Astrophysics Data System (ADS)

    Watkinson, E. J.; Ambrosi, R. M.; Kramer, D. P.; Williams, H. R.; Reece, M. J.; Chen, K.; Sarsfield, M. J.; Barklay, C. D.; Fenwick, H.; Weston, D. P.; Stephenson, K.

    2017-08-01

    European Space Agency radioisotope power systems will use americium oxide as the heat source in pellet or disc form. The oxide form is yet to be decided. Sintering trials with CeO2 and Nd2O3 as analogues for AmO2 and Am2O3 were conducted. Spark plasma sintering (SPS) and cold-press-and-sinter methods were compared. Different sintering parameters and particle characteristics were investigated with commercial and synthesised powders. The synthesised powders contained lath-shaped particles, and batches with different particle sizes and specific surface areas were made and sintered. This is the first study in the public literature to report the sintering of lath-shaped CeO2. The targeted density range of 85-90% was met using both techniques. No ball-milling was required. Cold-pressing-and-sintering CeO2 produced intact discs. Large cracking was prevalent in the SPS discs. Some powders pressed more successfully than others. Powder morphology had a significant effect on the result but it was not possible to fully quantify the effects in this study. The cold-pressed-and-sintered CeO2 discs had comparable Vickers hardness values to a nuclear ceramic (UO2). The hardness values were greater than the spark plasma sintered CeO2 sample. Efforts to SPS near-net shaped pellets using CeO2 and Nd2O3 are reported. A follow on investigation was conducted to assess how the 85-90% T.D. target could be achieved. The aspect ratio impacts the sintering parameters and behaviour. The Vickers hardness of Nd2O3 is reported for the first time and compared to the results of sintered CeO2.

  8. Investigation of the neutron spectrum of americium-beryllium sources by Bonner sphere spectrometry

    NASA Astrophysics Data System (ADS)

    Bedogni, R.; Domingo, C.; Roberts, N.; Thomas, D. J.; Chiti, M.; Esposito, A.; Garcia, M. J.; Gentile, A.; Liu, Z. Z.; de-San-Pedro, M.

    2014-11-01

    Americium-beryllium neutron sources are certainly the most widely used in neutron dosimetry laboratories, basically due to their long half-life and their energy distribution, which covers the energy domain of interest for many applications in ambient and personal dosimetry. Nevertheless, the spectrum of this source depends on the materials and dimension of the capsule and on the amount and physical-chemical properties of the active material, thus affecting relevant quantities such as the spectrum-averaged fluence-to-dose equivalent conversion coefficient. A EURAMET (European Association of National Metrology Institutes) project (n. 1104) was initiated to experimentally investigate how the neutron spectrum changes for different source sizes and encapsulations with a view to providing improved data for a planned revision of the ISO 8529 Standard Series. The experimental campaign was carried out in the low scatter facility at NPL. Here three different Bonner sphere spectrometers, BSSs, were exposed to the neutron fields produced by three different neutron sources formats: one X3 capsule (1 Ci) and two X14 capsules (10 Ci and 15 Ci). The specific advantage of the BSS is the large sensitivity to low-energy neutrons (E<0.1 MeV) which is the component expected to be most affected by the capsule-to-capsule variations and the component which is least well known. This paper summarises the results of the campaign with emphasis on (1) estimating the low-energy component of the Am-Be neutron spectrum, according to the encapsulation type; (2) evaluating the coherence between the Bonner spheres data and the previous studies performed with high-resolution spectrometers but limited in energy to E>0.1 MeV; (3) understanding whether the ISO-recommended Am-Be spectrum needs to be amended, and for which source formats.

  9. Some elements for a revision of the americium reference biokinetic model.

    PubMed

    Blanchardon, E; Leggett, R W; Eckerman, K F

    2007-01-01

    The interpretation of individual activity measurement after a contamination by 241Am or its parent nuclide 241Pu is based on the reference americium (Am) biokinetic model published by the International Commission on Radiological Protection in 1993 [International Commission on Radiological Protection. Age-dependent doses to members of the public from intake of radionuclides: Part 2 Ingestion dose coefficients. ICRP Publication 67. Ann. ICRP 23(3/4) (1993)]. The authors analysed the new data about Am biokinetics reported afterwards to propose an update of the current model. The most interesting results, from the United States Transuranium and Uranium Registries post-mortem measurement database [Filipy, R. E. and Russel, J. J. The United States Transuranium and Uranium Registries as sources for actinide dosimetry and bioeffects. Radiat. Prot. Dosim. 105(1-4), 185-187 (2003)] and the long-term follow-up of cases of inhalation intake [Malátová, I., Foltánová, S., Becková, V., Filgas, R., Pospísilová, H. and Hölgye, Z. Assessment of occupational doses from internal contamination with 241Am. Radiat. Prot. Dosim. 105(1-4), 325-328 (2003)], seemed to show that the current model underestimates the retention in the massive soft tissues and overestimates the retention in the skeleton and the late urinary excretion. However, a critical review of the data demonstrated that all were not equally reliable and suggested that only a slight revision of the model, possibly involving a change in the balance of activity between massive soft tissues, cortical and trabecular bone surfaces, may be required.

  10. Americium and plutonium association with magnesium hydroxide colloids in alkaline nuclear industry process environments

    NASA Astrophysics Data System (ADS)

    Maher, Zoe; Ivanov, Peter; O'Brien, Luke; Sims, Howard; Taylor, Robin J.; Heath, Sarah L.; Livens, Francis R.; Goddard, David; Kellet, Simon; Rand, Peter; Bryan, Nick D.

    2016-01-01

    The behaviours of Pu, Am and colloids in feed solutions to the Site Ion-exchange Effluent Plant (SIXEP) at the Sellafield nuclear reprocessing site in the U.K. have been studied. For both Pu and Am, fractions were found to be associated with material in the colloidal size range, with ˜50% of the Pu in the range 1-200 nm. The concentration of soluble Pu (<1 nm) was ˜1 nM, which is very similar to the solubility limit for Pu(V). The soluble Am concentration was of the order of 10-11 M, which was below the solubility limit of americium hydroxide. The size, morphology and elemental composition of the particulates and colloids in the feed solutions were investigated. Magnesium is homogeneously distributed throughout the particles, whereas U, Si, Fe, and Ca were present in localised areas only. Amongst some heterogeneous material, particles were identified that were consistent with hydrotalcite. The distribution of 241Am(III) on brucite (magnesium hydroxide) colloids of different sizes was studied under alkaline conditions representative of nuclear fuel storage pond and effluent feed solution conditions. The morphology of the brucite particles in the bulk material observed by ESEM was predominantly hexagonal, while that of the carbonated brucite consisted of hexagonal species mixed with platelets. The association of 241Am(III) with the brucite colloids was studied by ultrafiltration coupled with gamma ray-spectrometry. For carbonate concentrations up to 10-3 M, the 241Am(III) was mainly associated with larger colloids (>300 kDa), and there was a shift from the smaller size fractions to the larger over a period of 6 months. At higher carbonate concentrations (10-2 M), the Am was predominantly detected in the true solution fraction (<3 kDa) and in smaller size colloidal fractions, in the range 3-100 kDa.

  11. Americium-Curium Stabilization - 5'' Cylindrical Induction Melter System Design Basis

    SciTech Connect

    Witt, D.C.

    1999-11-08

    Approximately 11,000 liters (3,600) gallons of solution containing isotopes of Am and Cm are currently stored in F-Canyon Tank 17.1. These isotopes were recovered during plutonium-242 production campaigns in the mid- and late-1970s. Experimental work for the project began in 1995 by the Savannah River Technology Center (SRTC). Details of the process are given in the various sections of this document.

  12. Swelling under irradiation of MgO pellets containing americium oxide: The ECRIX-H irradiation experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Béjaoui, S.; Hanifi, K.; Valot, Ch.; Loubet, L.

    2011-06-01

    The ECRIX-H irradiation experiment studied the behaviour of pellets containing americium dispersed in MgO. The purpose of the irradiation was to demonstrate the capacity of magnesia to provide an efficient support matrix. After fabrication, the sintered pellets contained 16.65 wt.% of Am microdispersed in the inert matrix. The ECRIX-H pellets were irradiated under a locally moderated neutron flux in the Phénix sodium-cooled fast reactor (SFR) for 318 Effective Full Power Days (EFPD). Post-test calculations indicated that the fission and transmutation rates of americium at the maximum flux plane reached 33.9% and 92.6% respectively at the end of the irradiation phase. The results of the post-irradiation examinations - both non-destructive and destructive - are discussed in this paper. These results indicate a satisfactory behaviour of the MgO matrix. Particularly, a moderate swelling occurs in the pellets under irradiation even with significant quantities of helium generated and at high transmutation rate.

  13. Temperature and concentration dependences of the electrical resistivity for alloys of plutonium with americium under normal conditions

    SciTech Connect

    Tsiovkin, Yu. Yu. Povzner, A. A.; Tsiovkina, L. Yu.; Dremov, V. V.; Kabirova, L. R.; Dyachenko, A. A.; Bystrushkin, V. B.; Ryabukhina, M. V.; Lukoyanov, A. V.; Shorikov, A. O.

    2010-01-15

    The temperature and concentration dependences of the electrical resistivity for alloys of americium with plutonium are analyzed in terms of the multiband conductivity model for binary disordered substitution-type alloys. For the case of high temperatures (T > {Theta}{sub D}, {Theta}{sub D} is the Debye temperature), a system of self-consistent equations of the coherent potential approximation has been derived for the scattering of conduction electrons by impurities and phonons without any constraints on the interaction intensity. The definitions of the shift and broadening operator for a single-electron level are used to show qualitatively and quantitatively that the pattern of the temperature dependence of the electrical resistivity for alloys is determined by the balance between the coherent and incoherent contributions to the electron-phonon scattering and that the interference conduction electron scattering mechanism can be the main cause of the negative temperature coefficient of resistivity observed in some alloys involving actinides. It is shown that the great values of the observed resistivity may be attributable to interband transitions of charge carriers and renormalization of their effective mass through strong s-d band hybridization. The concentration and temperature dependences of the resistivity for alloys of plutonium and americium calculated in terms of the derived conductivity model are compared with the available experimental data.

  14. Preconcentration of low levels of americium and plutonium from waste waters by synthetic water-soluble metal-binding polymers with ultrafiltration

    SciTech Connect

    Smith, B.F.; Gibson, R.R.; Jarvinen, G.D.; Robison, T.W.; Schroeder, N.C.; Stalnaker, N.D.

    1997-12-31

    A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method has been optimized to give over 90% recovery and accountability from actual waste water.

  15. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    PubMed

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±δ ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±δ phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD.

  16. Transuranium isotopes

    SciTech Connect

    Hoffman, D.C.

    1985-12-01

    The needs of the research community for the production of transuranium isotopes, the quantities required, the continuity of production desired, and what a new steady state neutron source would have to provide to satisfy these needs are discussed. Examples of past frontier research which need these isotopes as well as an outline of the proposed Large Einsteinium Activation Program, LEAP, which requires roughly ten times the current production of /sup 254/Es are given. 15 refs., 5 figs., 4 tabs.

  17. Isotopic Paleoclimatology

    NASA Astrophysics Data System (ADS)

    Bowen, R.

    Paleotemperature scales were calculated by H. C. Urey and others in the 1950s to assess past temperatures, and later work using the stable isotopes of oxygen, hydrogen, and carbon employed standards such as Peedee belemnite (PDB) and Standard Mean Ocean Water (SMOW). Subsequently, subjects as diverse as ice volume and paleotemperatures, oceanic ice and sediment cores, Pleistocene/Holocene climatic changes, and isotope chronostratigraphy extending back to the Precambrian were investigated.

  18. Isotopic chirality

    SciTech Connect

    Floss, H.G.

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  19. [Assessment of the distribution in the body and the dose on the respiratory tract and organs after single, short-term and long-term inhalation of americium-241].

    PubMed

    Malykhin, V M

    1991-04-01

    On the basis of comparison of publications on accidental human intake of americium-241 and animal experimental studies dosimetric characteristics were obtained reflecting the dynamics of accumulation, formation of the dose on the organs and parts of the respiratory tract, as well as of the 24-hour elimination from the organism of the mentioned radionuclide following single, short- and long-term administration of americium-241 from the air. Results were obtained with the use of computers for quantitative modelling of the most complete metabolic transport scheme of americium.

  20. Peculiar Behavior of (U,Am)O(2-δ) Compounds for High Americium Contents Evidenced by XRD, XAS, and Raman Spectroscopy.

    PubMed

    Lebreton, Florent; Horlait, Denis; Caraballo, Richard; Martin, Philippe M; Scheinost, Andreas C; Rossberg, Andre; Jégou, Christophe; Delahaye, Thibaud

    2015-10-19

    In U(1-x)Am(x)O(2±δ) compounds with low americium content (x ≤ 20 atom %) and oxygen-to-metal (O/M) ratios close to 2.0, Am(III+) cations are charge-balanced by an equivalent amount of U(V+) cations while the fluorite structure of pure U(IV+)O2 is maintained. Up to now, it is unknown whether this observation also holds for higher americium contents. In this study, we combined X-ray diffraction with Raman and X-ray absorption spectroscopies to investigate a U(0.5)Am(0.5)O(2±δ) compound. Our results indicate that americium is again only present as Am(III+), while U(V+) remains below the amount required for charge balance. Unlike lower americium contents, this leads to an overall oxygen hypostoichiometry with an average O/M ratio of 1.92(2). The cationic sublattice is only slightly affected by the coexistence of large amounts of reduced (Am(III+)) and oxidized (U(V+)) cations, whereas significant deviations from the fluorite structure are evidenced by both extended X-ray absorption fine structure and Raman spectroscopies in the oxygen sublattice, with the observation of both vacancies and interstitials, the latter being apparently consistent with the insertion of U6O12 cuboctahedral-type clusters (as observed in the U4O9 or U3O7 phases). These results thus highlight the specificities of uranium-americium mixed oxides, which behave more like trivalent lanthanide-doped UO2 than U(1-x)Pu(x)O(2±δ) MOX fuels.

  1. LIBS Spectral Data for a Mixed Actinide Fuel Pellet Containing Uranium, Plutonium, Neptunium and Americium

    SciTech Connect

    Judge, Elizabeth J.; Berg, John M.; Le, Loan A.; Lopez, Leon N.; Barefield, James E.

    2012-06-18

    Laser-induced breakdown spectroscopy (LIBS) was used to analyze a mixed actinide fuel pellet containing 75% UO{sub 2}/20% PuO{sub 2}/3% AmO{sub 2}/2% NpO{sub 2}. The preliminary data shown here is the first report of LIBS analysis of a mixed actinide fuel pellet, to the authors knowledge. The LIBS spectral data was acquired in a plutonium facility at Los Alamos National Laboratory where the sample was contained within a glove box. The initial installation of the glove box was not intended for complete ultraviolet (UV), visible (VIS) and near infrared (NIR) transmission, therefore the LIBS spectrum is truncated in the UV and NIR regions due to the optical transmission of the window port and filters that were installed. The optical collection of the emission from the LIBS plasma will be optimized in the future. However, the preliminary LIBS data acquired is worth reporting due to the uniqueness of the sample and spectral data. The analysis of several actinides in the presence of each other is an important feature of this analysis since traditional methods must chemically separate uranium, plutonium, neptunium, and americium prior to analysis. Due to the historic nature of the sample fuel pellet analyzed, the provided sample composition of 75% UO{sub 2}/20% PuO{sub 2}/3% AmO{sub 2}/2% NpO{sub 2} cannot be confirm without further analytical processing. Uranium, plutonium, and americium emission lines were abundant and easily assigned while neptunium was more difficult to identify. There may be several reasons for this observation, other than knowing the exact sample composition of the fuel pellet. First, the atomic emission wavelength resources for neptunium are limited and such techniques as hollow cathode discharge lamp have different dynamics than the plasma used in LIBS which results in different emission spectra. Secondly, due to the complex sample of four actinide elements, which all have very dense electronic energy levels, there may be reactions and

  2. Monte Carlo modelling for in vivo measurements of Americium in a knee voxel phantom: general criteria for an international comparison.

    PubMed

    Gómez-Ros, J M; de Carlan, L; Franck, D; Gualdrini, G; Lis, M; López, M A; Moraleda, M; Zankl, M

    2007-01-01

    The general criteria and the scientific approach adopted for an 'International comparison on Monte Carlo modelling for in vivo measurement of Americium in a knee phantom' that is being organised within the EU Coordination Action CONRAD (Coordinated Network for Radiation Dosimetry) are described her. Detection system and a knee voxel phantom based on a computerised axial tomography of the Spitz anthropometric knee phantom with a homogeneous distribution of 241Am in bone have been considered for the simulation of three specific situations: (a) a single Low Energy Germanium detector for a point 241Am source in air; (b) the calculation of photon fluence spectra in air around the voxel phantom; and (c) the calculation of the energy distribution of pulses and peak detection efficiency in the real detection system geometry.

  3. Novel Americium Treatment Process for Surface Water and Dust Suppression Water

    SciTech Connect

    Tiepel, E.W.; Pigeon, P.; Nesta, S.; Anderson, J.

    2006-07-01

    The Rocky Flats Environmental Technology Site (RFETS), a former nuclear weapons production plant, has been remediated under CERCLA and decommissioned to become a National Wildlife Refuge. The site conducted this cleanup effort under the Rocky Flats Cleanup Agreement (RFCA) that established limits for the discharge of surface and process waters from the site. At the end of 2004, while a number of process buildings were undergoing decommissioning, routine monitoring of a discharge pond (Pond A-4) containing approximately 28 million gallons of water was discovered to have been contaminated with a trace amount of Americium-241 (Am-241). While the amount of Am-241 in the pond waters was very low (0.5 - 0.7 pCi/l), it was above the established Colorado stream standard of 0.15 pCi/l for release to off site drainage waters. The rapid successful treatment of these waters to the regulatory limit was important to the site for two reasons. The first was that the pond was approaching its hold-up limit. Without rapid treatment and release of the Pond A-4 water, typical spring run-off would require water management actions to other drainages onsite or a mass shuttling of water for disposal. The second reason was that this type of contaminated water had not been treated to the stringent stream standard at Rocky Flats before. Technical challenges in treatment could translate to impacts on water and secondary waste management, and ultimately, cost impacts. All of the technical challenges and specific site criteria led to the conclusion that a different approach to the treatment of this problem was necessary and a crash treatability program to identify applicable treatment techniques was undertaken. The goal of this program was to develop treatment options that could be implemented very quickly and would result in the generation of no high volume secondary waste that would be costly to dispose. A novel chemical treatment system was developed and implemented at the RFETS to treat Am

  4. Thermodynamic Features of the Complexation of Neodymium(III) and Americium(III) by Lactate in Trifluoromethanesulfonate Media.

    SciTech Connect

    Peter R. Zalupski; Leigh R. Martin; Kenneth L. Nash

    2010-10-01

    The protonation of lactate has been studied in a variety of electrolyte solutions using microcalorimetry to reveal a distinct medium influence imposed on the thermochemistry of the investigated equilibrium. The thermochemistry of lactate protonation, when studied directly in 1.0 M sodium lactate, agreed well with the studies performed in trifluoromethanesulfonate (triflate). This thermodynamic agreement suggests that the physical chemistry of lactate in the solutions applicable to the TALSPEAK process – a solvent extraction method for separating trivalent actinides from trivalent lanthanides within the scope of used nuclear fuel processing efforts – may be simulated in triflate solutions. Potentiometry, spectrophotometry and microcalorimetry have been subsequently used to study the thermodynamic features of neodymium and americium complexation by lactate using triflate as a strong background electrolyte. Three successive mononuclear lactate complexes were identified for Nd(III) and Am(III). The stability constants for neodymium, log ß1 = 2.60 ± 0.01, log ß2 = 4.66 ± 0.02 and log ß3 = 5.6 ± 0.1, and for americium, log ß1 = 2.60 ± 0.06, log ß2 = 4.7 ± 0.1 and log ß3 = 6.2 ± 0.2, were found to closely agree with the thermodynamic studies reported in sodium perchlorate solutions. Consequently, the thermodynamic medium effect, imposed on the TALSPEAK-related solution equilibria by the presence of strong background electrolytes such as NaClO4 and NaNO3, do not significantly impact the speciation in solution.

  5. ISOTOPE SEPARATORS

    DOEpatents

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  6. Americium and plutonium separation by extraction chromatography for determination by accelerator mass spectrometry.

    PubMed

    Kazi, Zakir H; Cornett, Jack R; Zhao, Xaiolei; Kieser, Liam

    2014-06-04

    A simple method was developed to separate Pu and Am using single column extraction chromatography employing N,N,N',N'-tetra-n-octyldiglycolamide (DGA) resin. Isotope dilution measurements of Am and Pu were performed using accelerator mass spectrometry (AMS) and alpha spectrometry. For maximum adsorption Pu was stabilized in the tetra valent oxidation state in 8M HNO3 with 0.05 M NaNO2 before loading the sample onto the resin. Am(III) was adsorbed also onto the resin from concentrated HNO3, and desorbed with 0.1 M HCl while keeping the Pu adsorbed. The on-column reduction of Pu(IV) to Pu(III) with 0.02 M TiCl3 facilitated the complete desorption of Pu. Interferences (e.g. Ca(2+), Fe(3+)) were washed off from the resin bed with excess HNO3. Using NdF3, micro-precipitates of the separated isotopes were prepared for analysis by both AMS and alpha spectrometry. The recovery was 97.7±5.3% and 95.5±4.6% for (241)Am and (242)Pu respectively in reagents without a matrix. The recoveries of the same isotopes were 99.1±6.0 and 96.8±5.3% respectively in garden soil. The robustness of the method was validated using certified reference materials (IAEA 384 and IAEA 385). The measurements agree with the certified values over a range of about 1-100 Bq kg(-1). The single column separation of Pu and Am saves reagents, separation time, and cost.

  7. Selective separation of americium from europium using 2,9-bis(triazine)-1,10-phenanthrolines in ionic liquids: a new twist on an old story

    DOE PAGES

    Williams, Neil J.; Dehaudt, Jeremy; Bryantsev, Vyacheslav S.; ...

    2017-02-10

    Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, their limited solubility in traditional solvents remains a technological bottleneck. Here in this paper we report our recent work using a simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved in an ionic liquid (IL), demonstrating the efficacy of IL extraction systems for the selective separation of americium from europium, achieving separation factors in excess of 7500 and selectively removing up to 99% of the americium. Characterization of the coordination environment was performed using a combination ofmore » X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations.« less

  8. Selective separation of americium from europium using 2,9-bis(triazine)-1,10-phenanthrolines in ionic liquids: a new twist on an old story.

    PubMed

    Williams, Neil J; Dehaudt, Jérémy; Bryantsev, Vyacheslav S; Luo, Huimin; Abney, Carter W; Dai, Sheng

    2017-02-28

    Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, their limited solubility in traditional solvents remains a technological bottleneck. Herein we report our recent work using a simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved in an ionic liquid (IL), demonstrating the efficacy of IL extraction systems for the selective separation of americium from europium, achieving separation factors in excess of 7500 and selectively removing up to 99% of the americium. Characterization of the coordination environment was performed using a combination of X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations.

  9. Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium-americium mixed oxides

    NASA Astrophysics Data System (ADS)

    Prieur, D.; Lebreton, F.; Martin, P. M.; Caisso, M.; Butzbach, R.; Somers, J.; Delahaye, T.

    2015-10-01

    Uranium-americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U1-xAmxO2±δ samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U1-xAmxO2±δ leads to the formation of similar fluorite solid solution indicating the presence of Am+III and U+V in equimolar proportions.

  10. Concordant plutonium-241-americium-241 dating of environmental samples: results from forest fire ash

    SciTech Connect

    Goldstein, Steven J; Oldham, Warren J; Murrell, Michael T; Katzman, Danny

    2010-12-07

    We have measured the Pu, {sup 237}Np, {sup 241}Am, and {sup 151}Sm isotopic systematics for a set of forest fire ash samples from various locations in the western U.S. including Montana, Wyoming, Idaho, and New Mexico. The goal of this study is to develop a concordant {sup 241}Pu (t{sub 1/2} = 14.4 y)-{sup 241}Am dating method for environmental collections. Environmental samples often contain mixtures of components including global fallout. There are a number of approaches for subtracting the global fallout component for such samples. One approach is to use {sup 242}/{sup 239}Pu as a normalizing isotope ratio in a three-isotope plot, where this ratio for the nonglobal fallout component can be estimated or assumed to be small. This study investigates a new, complementary method of normalization using the long-lived fission product, {sup 151}Sm (t{sub 1/2} = 90 y). We find that forest fire ash concentrates actinides and fission products with {approx}1E10 atoms {sup 239}Pu/g and {approx}1E8 atoms {sup 151}Sm/g, allowing us to measure these nuclides by mass spectrometric (MIC-TIMS) and radiometric (liquid scintillation counting) methods. The forest fire ash samples are characterized by a western U.S. regional isotopic signature representing varying mixtures of global fallout with a local component from atmospheric testing of nuclear weapons at the Nevada Test Site (NTS). Our results also show that {sup 151}Sm is well correlated with the Pu nuclides in the forest fire ash, suggesting that these nuclides have similar geochemical behavior in the environment. Results of this correlation indicate that the {sup 151}Sm/{sup 239}Pu atom ratio for global fallout is {approx}0.164, in agreement with an independent estimate of 0.165 based on {sup 137}Cs fission yields for atmospheric weapons tests at the NTS. {sup 241}Pu-{sup 241}Am dating of the non-global fallout component in the forest fire ash samples yield ages in the late 1950's-early 1960's, consistent with a peak in NTS

  11. Assessment of Neptunium, Americium, and Curium in the Savannah River Site Environment

    SciTech Connect

    Carlton, W.H.

    1997-12-17

    A series of documents has been published in which the impact of various radionuclides released to the environment by Savannah River Site (SRS) operations has been assessed. The quantity released, the disposition of the radionuclides in the environment, and the dose to offsite individuals has been presented for activation products, carbon cesium, iodine, plutonium, selected fission products, strontium, technetium, tritium, uranium, and the noble gases. An assessment of the impact of nonradioactive mercury also has been published.This document assesses the impact of radioactive transuranics released from SRS facilities since the first reactor became operational late in 1953. The isotopes reported here are 239Np, 241Am, and 244Cm.

  12. Determining the americium transmutation rate and fission rate by post-irradiation examination within the scope of the ECRIX-H experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Pontillon, Y.; Esbelin, E.; Béjaoui, S.; Pasquet, B.; Bourdot, P.; Bonnerot, J. M.

    2013-09-01

    The ECRIX-H experiment aims to assess the feasibility of transmuting americium micro-dispersed in an inert magnesia matrix under a locally moderated neutron flux in the Phénix reactor. A first set of examinations demonstrated that pellet behaviour was satisfactory with moderate swelling at the end of the irradiation. Additional post-irradiation examinations needed to be conducted to confirm the high transmutation rate so as to definitively conclude on the success of the ECRIX-H experiment. This article presents and discusses the results of these new examinations. They confirm the satisfactory behaviour of the MgO matrix not only during the basic irradiation but also during post-irradiation thermal transients. These examinations also provide additional information on the behaviour of fission products both in the americium-based particles and in the MgO matrix. These results particularly validate the transmutation rate predicted by the calculation codes using several different analytical techniques. The fission rate is also determined. Moderate pellet swelling under irradiation (6.7 vol.%), while only 23% of the produced He and 4% of the fission gases were released from the fuel. No interaction between the pellets and the cladding. Formation of bubbles due to the precipitation of fission gases and He mainly in bubbles located inside the americium-based particles. These bubbles are the main cause of macroscopic swelling in the pellets. Well-crystallised structure of the MgO matrix which shows no amorphisation after irradiation despite the presence of fission products. The absence of any reaction of MgO with the americium-based phase, Formation of a PuO2-type crystalline phase from AmO1.62 particles following the Am transmutation process. A shielded electron probe micro-analyser (EPMA) 'CAMECA' Camebax equipped to collect and exploit the measurements using the 'SAMx' system. A Philips XL30 scanning electron microscope (SEM). Field acquisitions were performed thanks to

  13. Isotope materials availability and services for target production at the Oak Ridge National Laboratory

    SciTech Connect

    Ratledge, J.E.; Dahl, T.L.; Ottinger, C.L.; Aaron, W.S.; Adair, H.L.

    1986-01-01

    Materials available through the Isotope Distribution Program include separated stable isotopes, byproduct radiosotopes, and research quantities of source and special nuclear materials. Isotope products are routinely available in the forms listed in the product description section of the Isotopes Products and Services Catalog distributed by the Oak Ridge National Laboratory (ORNL). Different forms can be provided in some cases, usually at additional cost. Routinely available services include cyclotron target irradiations, fabrication of special physical forms, source encapsulation, ion implantation, and special purifications. Materials and services that are not offered as part of the routine distribution program may be made available from commercial sources in the United States. Specific forms of isotopic research materials include thin films and foils for use as accelerator targets, metal or other compounds in the form of bars or wires, and metal sheets. Methods of fabrication include evaporation, sputtering, rolling, electrolytic deposition, pressing, sintering, and casting. High-purity metal forms of plutonium, americium, and curium are prepared by vacuum reduction/distillation. Both fissionable and nonfissionable neutron dosimeters are prepared for determining the neutron energy spectra, flux, and fluence at various locations within a reactor. Details on what materials are available and how the materials and related services can be obtained from ORNL are described.

  14. Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

    SciTech Connect

    Prieur, D.; Lebreton, F.; Somers, J.; Delahaye, T.

    2015-10-15

    Uranium–americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U{sub 1−x}Am{sub x}O{sub 2±δ} samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U{sub 1−x}Am{sub x}O{sub 2±δ} leads to the formation of similar fluorite solid solution indicating the presence of Am{sup +III} and U{sup +V} in equimolar proportions. - Graphical abstract: Formation of (U{sup IV/V},Am{sup III})O{sup 2} solid solution by sol–gel and by powder metallurgy. - Highlights: • Uranium–americium mixed oxides were synthesized by sol–gel and powder metallurgy. • Fluorite solid solutions with similar local environment have been obtained. • U{sup V} and Am{sup III} are formed in equimolar proportions.

  15. Isotope fractionation

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    A rash of new controversy has emerged around the subject of mass-independent isotope fractionation effects, particularly in the case of the oxygen isotopes. To be sure, the controversy has been around for awhile, but it has been given new impetus by the results of a recent study by Mark H. Thiemens and John E. Heidenreich III of the University of California, San Diego (Science, March 4, 1983).Gustav Arrhenius has been trying to convince the planetary science community that chemical effects in isotope fractionation processes could explain observations in meteorites that appear to be outside of the traditionally understood mass-dependent fractionations (G. Arrhenius, J . L. McCrumb, and N. F. Friedman, Astrophys. Space Sci, 65, 297, 1974). Robert Clayton had made the basic observations of oxygen in carbonaceous chondrites that the slope of the δ17 versus δ18 line was 1 instead of the slope of ½ characteristic of terrestrial rocks and lunar samples (Ann. Rev. Nucl. Part. Sci., 28, 501, 1978). The mass-independent effects were ascribed to the apparent contribution of an ancient presolar system component of O16.

  16. Impact of environmental curium on plutonium migration and isotopic signatures.

    PubMed

    Kurosaki, Hiromu; Kaplan, Daniel I; Clark, Sue B

    2014-12-02

    Plutonium (Pu), americium (Am), and curium (Cm) activities were measured in sediments from a former radioactive waste disposal basin located on the Savannah River Site, South Carolina, and in subsurface aquifer sediments collected downgradient from the basin. In situ Kd values (Pu concentration ratio of sediment/groundwater) derived from this field data and previously reported groundwater concentration data compared well to laboratory Kd values reported in the literature. Pu isotopic signatures confirmed multiple sources of Pu contamination. The ratio of (240)Pu/(239)Pu was appreciably lower for sediment samples compared to the associated groundwater. This isotopic ratio difference may be explained by the following: (1) (240)Pu produced by decay of (244)Cm may exist predominantly in high oxidation states (Pu(V)O2(+) and Pu(VI)O2(2+)) compared to Pu derived from the disposed waste effluents, and (2) oxidized forms of Pu sorb less to sediments than reduced forms of Pu. Isotope-specific Kd values calculated from measured Pu activities in the sediments and groundwater indicated that (240)Pu, which is derived primarily from the decay of (244)Cm, had a value of 10 ± 2 mL g(-1), whereas (239)Pu originating from the waste effluents discharged at the site had a value of 101 ± 8 mL g(-1). One possible explanation for the isotope-specific sorption behavior is that (240)Pu likely existed in the weaker sorbing oxidation states, +5 or +6, than (239)Pu, which likely existed in the +3 or +4 oxidation states. Consequently, remediation strategies for radioactively contaminated systems must consider not only the discharged contaminants but also their decay products. In this case, mitigation of Cm as well as Pu will be required to completely address Pu migration from the source term.

  17. Intramolecular sensitization of americium luminescence in solution: Shining light on short-lived forbidden 5f transitions

    SciTech Connect

    Sturzbecher-Hoehne, M.; Yang, P.; D'Aleo, A.; Abergel, R. J.

    2016-03-10

    In this study, the photophysical properties and solution thermodynamics of water soluble trivalent americium (AmIII) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for AmIII, generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10–3 to 10–2%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of AmIII assigned to the 5D17F1 f–f transition was exploited to characterize the high proton-independent stability of the complex formed with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these AmIII complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.

  18. Intramolecular sensitization of americium luminescence in solution: Shining light on short-lived forbidden 5f transitions

    DOE PAGES

    Sturzbecher-Hoehne, M.; Yang, P.; D'Aleo, A.; ...

    2016-03-10

    In this study, the photophysical properties and solution thermodynamics of water soluble trivalent americium (AmIII) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for AmIII, generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10–3 to 10–2%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of AmIII assigned to the 5D1 → 7F1 f–f transition was exploited to characterize the high proton-independent stability of the complex formedmore » with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these AmIII complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.« less

  19. EURADOS INTERCOMPARISON ON MEASUREMENTS AND MONTE CARLO MODELLING FOR THE ASSESSMENT OF AMERICIUM IN A USTUR LEG PHANTOM

    SciTech Connect

    Lopez, M. A.; Broggio, D.; Capello, K.; Cardenas-Mendez, E.; El-Faramawy, N.; Franck, D.; James, Anthony C.; Kramer, Gary H.; Lacerenza, G.; Lynch, Timothy P.; Navarro, J. F.; Navarro, T.; Perez, B.; Ruhm, W.; Tolmachev, Sergei Y.; Weitzenegger, E.

    2011-03-01

    United States Transuranium and Uranium Registries (USTUR) Case 0102 was the first whole-body donation to the USTUR (1979), of a worker affected by a substantial accidental 241Am intake(1). Half of this man’s skeleton, encased in tissue-quivalent plastic, provides a unique human ‘phantom’ for calibrating in vivo counting systems. In this case, the 241Am skeletal activity was measured 25 y after the intake. Approximately 82 % of the 241Am remaining in the body was found in the bones and teeth. The241Am activity concentration throughout the skeleton (in all types of bone) was fairly uniform(2). A protocol has been proposed by a group of in vivo laboratories from Europe [CIEMAT-Spain, IRSN-France and Helmholtz Zentrum Mu¨nchen (HMGU)-Germany] and Canada (HML) participating in this DOS/USTUR intercomparison. The focus areas for the study included: (1) the efficiency pattern along the leg phantom using Germanium detectors (experimental and computational), (2) the comparison of Monte Carlo (MC) results with experimental values in counting efficiency data and (3) the inflence of americium distribution in the bone material (volume or surface).

  20. Intramolecular sensitization of americium luminescence in solution: shining light on short-lived forbidden 5f transitions.

    PubMed

    Sturzbecher-Hoehne, M; Yang, P; D'Aléo, A; Abergel, R J

    2016-06-14

    The photophysical properties and solution thermodynamics of water soluble trivalent americium (Am(III)) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for Am(III), generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10(-3) to 10(-2)%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of Am(III) assigned to the (5)D1 → (7)F1 f-f transition was exploited to characterize the high proton-independent stability of the complex formed with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these Am(III) complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.

  1. Treatment of human contamination with plutonium and americium: would orally administered Ca- or Zn-DTPA be effective?

    PubMed

    Taylor, David M; Hodgson, Susan A; Stradling, Neil

    2007-01-01

    Accidental or deliberate dispersion of plutonium (Pu) and americium (Am) into the public environment could contaminate large numbers of people by inhalation. If measures to reduce the internal dose are considered appropriate, oral administration of either calcium (Ca) or zinc (Zn) diethylenetriaminepenta-acetic acid (DTPA) would be the simplest treatment. Published experimental data from rats on the effects of oral DTPA on the retention of inhaled Pu and Am show that: (1) orally administered Zn-DTPA is as effective as repeated intravenous injection for the decorporation of Pu and Am inhaled as nitrates, although higher dosages are required; (2) oral Zn-DTPA appears to be an effective treatment for Am dioxide but not Pu dioxide; (3) maximum decorporation of Pu, by oral or intravenous administration, requires a large molar excess of Zn-DTPA over Pu (>1 x 10(6)); (4) neither oral nor injected Zn-DTPA are likely to be effective for Pu oxides, nor when Pu and Am nitrates are mixed with other dusts. It is concluded that oral administration of a simple aqueous solution of Zn-DTPA could be an important treatment in accident or emergency scenarios after intake of pure chemical forms of Pu and Am, which are highly or moderately soluble in biological fluids. However, more research is needed on the efficacy of treatment when these forms are mixed with other materials. Importantly, studies designed to increase the efficiency of uptake of DTPA from the gastrointestinal tract could appreciably reduce the dosage.

  2. Nano-cerium vanadate: a novel inorganic ion exchanger for removal of americium and uranium from simulated aqueous nuclear waste.

    PubMed

    Banerjee, Chayan; Dudwadkar, Nilesh; Tripathi, Subhash Chandra; Gandhi, Pritam Maniklal; Grover, Vinita; Kaushik, Chetan Prakash; Tyagi, Avesh Kumar

    2014-09-15

    Cerium vanadate nanopowders were synthesized by a facile low temperature co-precipitation method. The product was characterized by X-ray diffraction and transmission electron microscopy and found to consist of ∼25 nm spherical nanoparticles. The efficiency of these nanopowders for uptake of alpha-emitting radionuclides (233)U (4.82 MeV α) and (241)Am (5.49 MeV α, 60 keV γ) has been investigated. Thermodynamically and kinetically favorable uptake of these radionuclides resulted in their complete removal within 3h from aqueous acidic feed solutions. The uptake capacity was observed to increase with increase in pH as the zeta potential value decreased with the increase in pH but effect of ionic strength was insignificant. Little influence of the ions like Sr(2+), Ru(3+), Fe(3+), etc., in the uptake process indicated CeVO4 nanopowders to be amenable for practical applications. The isotherms indicated predominant uptake of the radioactive metal ions in the solid phase of the exchanger at lower feed concentrations and linear Kielland plots with positive slopes indicated favorable exchange of the metal ions with the nanopowder. Performance comparison with the other sorbents reported indicated excellent potential of nano-cerium vanadate for removing americium and uranium from large volumes of aqueous acidic solutions.

  3. Theoretical investigation of pressure-induced structural transitions in americium using GGA+U and hybrid density functional theory methods

    NASA Astrophysics Data System (ADS)

    Verma, Ashok K.; Modak, P.; Sharma, Surinder M.; Svane, A.; Christensen, N. E.; Sikka, S. K.

    2013-07-01

    First-principles calculations have been performed for americium (Am) metal using the generalized gradient approximation + orbital-dependent onsite Coulomb repulsion via Hubbard interaction (GGA+U) and hybrid density functional theory (HYB-DFT) methods to investigate various ground state properties and pressure-induced structural transitions. Both methods yield equilibrium volume and bulk modulus in good agreement with the experimental results. The GGA+spin orbit coupling+U method reproduced all structural transitions under pressure correctly, but the HYB-DFT method failed to reproduce the observed Am-I to Am-II transition. Good agreement was found between calculated and experimental equations of states for all phases, but the first three phases need larger U (α) parameters (where α represents the fraction of Hartree-Fock exchange energy replacing the DFT exchange energy) than the fourth phase in order to match the experimental data. Thus, neither the GGA+U nor the HYB-DFT methods are able to describe the energetics of Am metal properly in the entire pressure range from 0 GPa to 50 GPa with a single choice of their respective U and α parameters. Low binding-energy peaks in the experimental photoemission spectrum at ambient pressure relate, for some parameter choices, well to peak positions in the calculated density of states function of Am-I.

  4. Evaluation of synthetic water-soluble metal-binding polymers with ultrafiltration for selective concentration of americium and plutonium

    SciTech Connect

    Smith, B.F.; Gibson, R.R.; Jarvinen, G.D.; Jones, M.M.; Lu, M.T.; Robison, T.W.; Schroeder, N.C.; Stalnaker, N.

    1997-12-31

    Routine counting methods and ICP-MS are unable to directly measure the new US Department of Energy (DOE) regulatory level for discharge waters containing alpha-emitting radionuclides of 30 pCi/L total alpha or the 0.05 pCi/L regulatory level for Pu or Am activity required for surface waters at the Rocky Flats site by the State of Colorado. This inability indicates the need to develop rapid, reliable, and robust analytical techniques for measuring actinide metal ions, particularly americium and plutonium. Selective separation or preconcentration techniques would aid in this effort. Water-soluble metal-binding polymers in combination with ultrafiltration are shown to be an effective method for selectively removing dilute actinide ions from acidic solutions of high ionic strength. The actinide-binding properties of commercially available water-soluble polymers and several polymers which have been reported in the literature were evaluated. The functional groups incorporated in the polymers were pyrrolidone, amine, oxime, and carboxylic, phosphonic, or sulfonic acid. The polymer containing phosphonic acid groups gave the best results with high distribution coefficients and concentration factors for {sup 241}Am(III) and {sup 238}Pu(III)/(IV) at pH 4 to 6 and ionic strengths of 0.1 to 4.

  5. Chemical Speciation of Strontium, Americium, and Curium in High Level Waste: Predictive Modeling of Phase Partitioning During Tank Processing

    SciTech Connect

    Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.; Campbell, James A.

    1999-06-01

    In this research program, Pacific Northwest National Laboratory (PNNL) and Florida State University (FSU) are investigating the speciation of strontium and americium/curium in the presence of selected organic chelating agents (ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl) aethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), and iminodiacetic acid (IDA)) over ranges of hydroxide, carbonate, ionic strength, and competing metal ion concentrations present in high-level waste tanks. The project is composed of integrated research tasks that approach the problem of chemical speciation using macroscopic thermodynamic measurements of metal-ligand competition reactions, molecular modeling studies to identify structures or complexes of unusual stability, and mass spectrometry measurements of complex charge/mass ratio that can be applied to mixed metal-chelate systems. This fundamental information is then used to develop thermodynamic models, which allow the prediction of changes in chemical speciation and solubility that can occur in response to changes in tank processing conditions. In this way, we can develop new approaches that address fundamental problems in aqueous speciation and at the same time provide useful and practical information needed for tank processing.

  6. Highly enriched isotopes of uranium and transuranium elements for scientific investigation

    NASA Astrophysics Data System (ADS)

    Vesnovskii, Stanislav P.; Polynov, Vladimir N.

    1992-08-01

    The paper describes the production of highly enriched isotopes of uranium, plutonium, americium and curium by means of electromagnetic separation for scientific and applied research in physics, chemistry, geology and other fields. The equipment and radiochemical methods used allows to provide the isotopic pure samples in quantities sufficient to set up nuclear physics experiments, to produce reference materials and standard sources for calibration of radiometrical and mass spectrometrical equipment and for use in radionuclear metrology. For a series of nuclei unique characteristics of isotopic enrichment and radiochemical and chemical purity were achieved: 233U: 99.97%; 235U: 99.97%; 236U: 98.0%; 238U: 99.997%; 238Pu: 99.6%; 239Pu: 99.9977%; 240Pu: 99.9-100%; 241Pu: 96.998%; 242Pu: 97.8-99.96%; 244Pu: 96.7%; 241Am: 99.6%; 242mAm: 85.6%; 243Am: 99.2-99.94%; 243Cm: 99.99%; 245Cm: 99.998%; 246Cm: 99.8%; 247Cm: 90%; 248Cm: 97%. Methods of radiochemical and chemical separation, product certification, fabrication of special sources or targets and layers of highly enriched isotopes on various substrates are presented.

  7. Implications of Plutonium isotopic separation on closed fuel cycles and repository design

    SciTech Connect

    Forsberg, C.

    2013-07-01

    Advances in laser enrichment may enable relatively low-cost plutonium isotopic separation. This would have large impacts on LWR closed fuel cycles and waste management. If Pu-240 is removed before recycling plutonium as mixed oxide (MOX) fuel, it would dramatically reduce the buildup of higher plutonium isotopes, Americium, and Curium. Pu-240 is a fertile material and thus can be replaced by U-238. Eliminating the higher plutonium isotopes in MOX fuel increases the Doppler feedback, simplifies reactor control, and allows infinite recycle of MOX plutonium in LWRs. Eliminating fertile Pu-240 and Pu-242 reduces the plutonium content in MOX fuel and simplifies fabrication. Reducing production of Pu-241 reduces production of Am-241 - the primary heat generator in spent nuclear fuels after several decades. Reducing heat generating Am-241 would reduce repository cost and waste toxicity. Avoiding Am- 241 avoids its decay product Np-237, a nuclide that partly controls long-term oxidizing repository performance. Most of these benefits also apply to LWR plutonium recycled into fast reactors. There are benefits for plutonium isotopic separation in fast reactor fuel cycles (particularly removal of Pu-242) but the benefits are less. (author)

  8. Method for separating isotopes

    DOEpatents

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  9. Isotope separation by photochromatography

    DOEpatents

    Suslick, K.S.

    1975-10-03

    A photochromatographic method for isotope separation is described. An isotopically mixed molecular species is adsorbed on an adsorptive surface, and the adsorbed molecules are irradiated with radiation of a predetermined wavelength which will selectively excite desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thus separate them from the undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes. (BLM)

  10. Isotope separation by photochromatography

    DOEpatents

    Suslick, Kenneth S.

    1977-01-01

    An isotope separation method which comprises physically adsorbing an isotopically mixed molecular species on an adsorptive surface and irradiating the adsorbed molecules with radiation of a predetermined wavelength which will selectively excite a desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thereby separate them from the unexcited undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes.

  11. Decorporation of systemically distributed americium by a novel orally administered diethylenetriaminepentaacetic acid (DTPA) formulation in beagle dogs.

    PubMed

    Wilson, James P; Cobb, Ronald R; Dungan, Nathanael W; Matthews, Laura L; Eppler, Bärbel; Aiello, Kenneth V; Curtis, Shiro; Boger, Teannetta; Guilmette, Raymond A; Weber, Waylon; Doyle-Eisele, Melanie; Talton, James D

    2015-03-01

    Novel decorporation agents are being developed to protect against radiological accidents and terrorists attacks. Radioactive americium is a significant component of nuclear fallout. Removal of large radioactive materials, such as 241Am, from exposed persons is a subject of significant interest due to the hazards they pose. The objective of this study was to evaluate the dose-related efficacy of daily doses of NanoDTPA™ Capsules for decorporating Am administered intravenously as a soluble citrate complex to male and female beagle dogs. In addition, the efficacy of the NanoDTPA™ Capsules for decorporating 241Am was directly compared to intravenously administered saline and DTPA. Animals received a single IV administration of 241Am(III)-citrate on Day 0. One day after radionuclide administration, one of four different doses of NanoDTPA™ Capsules [1, 2, or 6 capsules d(-1) (30 mg, 60 mg, or 180 mg DTPA) or 2 capsules BID], IV Zn-DTPA (5 mg kg(-1) pentetate zinc trisodium) as a positive control, or IV saline as a placebo were administered. NanoDTPA™ Capsules, IV Zn-DTPA, or IV saline was administered on study days 1-14. Animals were euthanized on day 21. A full necropsy was conducted, and liver, spleen, kidneys, lungs and trachea, tracheobronchial lymph nodes (TBLN), muscle samples (right and left quadriceps), gastrointestinal (GI) tract (stomach plus esophagus, upper and lower intestine), gonads, two femurs, lumbar vertebrae (L1-L4), and all other soft tissue remains were collected. Urinary and fecal excretion profiles were increased approximately 10-fold compared to those for untreated animals. Tissue contents were decreased compared to untreated controls. In particular, liver content was decreased by approximately eightfold compared to untreated animals. The results from this study further demonstrate that oral NanoDTPA™ Capsules are equally efficient compared to IV Zn-DTPA in decorporation of actinides.

  12. Increased retention of americium in kidneys as compared with plutonium in an actinide wound contamination model in the rat.

    PubMed

    Griffiths, Nina M; Coudert, Sylvie; Molina, Thibaut; Wilk, Jean-Claude; Renault, Daniel; Berard, Philippe; Van der Meeren, Anne

    2014-11-01

    Americium-241 ((241)Am) presents a potential risk for nuclear industry workers associated with reactor decommissioning and aging combustible materials. The purpose of this study was to investigate Am renal retention after actinide contamination by wounding in the rat. Anesthetized rats were contaminated with Mixed Oxide (MOX) (7.1% Plutonium [Pu] by mass and containing 27% Am as % total alpha activity), Pu or Am nitrate following an incision wound of the hind leg. Times of euthanasia ranged from 2 hours to 5 months after contamination. Pu and Am levels were quantified following radiochemistry and alpha-spectrophotometry. Initial data show that over the experimental period the proportion of Am in kidneys as a fraction of total kidney alpha activity was elevated as compared to MOX powder indicating a specific retention in this organ. The percentage of Pu was similar to the powder. After MOX contamination, kidney to liver ratios appeared to increase more markedly for Am (from 0.2 at 7 days to 0.6 at 90 days) as compared with Pu (0.1 at 7 days to 0.2 at 90 days). In accordance with tissue actinide retention the dose from Am to the kidney increases with time. For comparison, the ratio of estimated equivalent doses due to Am to kidney is 1.5-fold greater than for Pu (around 90 versus 60 mSv). After actinide contamination of wounds, Am is concentrated in the kidneys as compared to Pu leading to potential exposure of renal tissue to both alpha particles and gamma radiation.

  13. Fabrication and characterization of U1-xAmxO2±δ compounds with high americium contents (x = 0.3, 0.4 and 0.5)

    NASA Astrophysics Data System (ADS)

    Lebreton, Florent; Horlait, Denis; Delahaye, Thibaud; Blanchart, Philippe

    2013-08-01

    Mixed uranium-americium oxides are considered promising compounds for americium transmutation in fast neutron reactors. A better understanding of these materials and of the U-Am-O phase diagram is, however, needed. Though many results in the literature describe U1-xAmxO2±δ (x ⩽ 0.2) compounds, very few studies concern higher Am contents. In this context, this article reports the fabrication method of U1-xAmxO2±δ (0.3 ⩽ x ⩽ 0.5) and their preliminary characterization, notably by X-ray diffraction.

  14. Management of Heavy Isotope in the DOE Complex

    SciTech Connect

    Canon, R.; Croff, A.; Boyd, L.

    2002-02-27

    cost to the user of obtaining newly produced material. The HIMG has also prepared issue papers on neptunium and americium/curium that identify the resources, potential uses, and disposal pathways for the materials across the DOE Complex. In the future the HIMG expects to comprehensively identify the status of the U.S. heavy isotope inventory, prepare additional issue papers and plans charting the future of this inventory, and to facilitate execution of the plan.

  15. Direct isotope ratio analysis of individual uranium-plutonium mixed particles with various U/Pu ratios by thermal ionization mass spectrometry.

    PubMed

    Suzuki, Daisuke; Esaka, Fumitaka; Miyamoto, Yutaka; Magara, Masaaki

    2015-02-01

    Uranium and plutonium isotope ratios in individual uranium-plutonium (U-Pu) mixed particles with various U/Pu atomic ratios were analyzed without prior chemical separation by thermal ionization mass spectrometry (TIMS). Prior to measurement, micron-sized particles with U/Pu ratios of 1, 5, 10, 18, and 70 were produced from uranium and plutonium certified reference materials. In the TIMS analysis, the peaks of americium, plutonium, and uranium ion signals were successfully separated by continuously increasing the evaporation filament current. Consequently, the uranium and plutonium isotope ratios, except the (238)Pu/(239)Pu ratio, were successfully determined for the particles at all U/Pu ratios. This indicates that TIMS direct analysis allows for the measurement of individual U-Pu mixed particles without prior chemical separation.

  16. RFNC-VNIIEF Capabilities to Production High Pure Isotopes for Scientific and Medical Applications

    SciTech Connect

    Vesnovskii, S. P.

    2002-02-26

    In the technical paper there is presented the information on the basic equipment and more than thirty-year experience of RFNC-VNIIEF activities in the sphere of producing highly enriched isotopes of actinide elements--thorium, uranium, neptunium, plutonium, americium and curium--for scientific researches and practical applications. Electromagnetic separator and radiochemical methods provide obtaining of superpure isotope samples for nuclear-physical radiometric and mass-spectrometric equipment, and also as tracers when analyzing environmental contamination. There are presented the structure of the laboratory occupied with these isotopes electromagnetic separation as well as the nomenclature and characteristics of the specimens supplied. There are stated science and engineering elaborations of technologies aimed at producing alpha-ray radiating radionuclides--thorium-229, thorium-228, actinium-225, radium-224--for the purpose of anti-cancer therapy using bismuth-212 and bismuth-213 produced by the specially developed generators. There are presented the basic directions of cooperation with other Russian Institutes in developing this promising line of conversion.

  17. Statistical clumped isotope signatures

    NASA Astrophysics Data System (ADS)

    Röckmann, Thomas; Popa, Maria Elena; Krol, Maarten; Hofmann, Magdalena

    2016-04-01

    High precision measurements of molecules containing more than one heavy isotope in environmental samples are becoming available with new instrumentation and may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk isotopic composition of the molecule, which for rare heavy isotopes is approximated by the arithmetic average of the isotope ratios of single substituted atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies when the indistinguishable atoms are from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule and these anomalies have to be taken into account in data interpretation. The size of the signal is closely related to the relative standard deviation of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules.

  18. METHOD OF ISOTOPE CONCENTRATION

    DOEpatents

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  19. Statistical clumped isotope signatures

    PubMed Central

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  20. Statistical clumped isotope signatures

    NASA Astrophysics Data System (ADS)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-08-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules.

  1. Cosmic ray isotopes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1973-01-01

    The isotopic composition of cosmic rays is studied in order to develop the relationship between cosmic rays and stellar processes. Cross section and model calculations are reported on isotopes of H, He, Be, Al and Fe. Satellite instrument measuring techniques separate only the isotopes of the lighter elements.

  2. Isotope reference materials

    USGS Publications Warehouse

    Coplen, Tyler B.

    2010-01-01

    Measurement of the same isotopically homogeneous sample by any laboratory worldwide should yield the same isotopic composition within analytical uncertainty. International distribution of light element isotopic reference materials by the International Atomic Energy Agency and the U.S. National Institute of Standards and Technology enable laboratories to achieve this goal.

  3. Generation of Radixenon Isotopes

    SciTech Connect

    McIntyre, Justin I.; Bowyer, Ted W.; Hayes, James C.; Heimbigner, Tom R.; Morris, Scott J.; Panisko, Mark E.; Pitts, W. K.; Pratt, Sharon L.; Reeder, Paul L.; Thomas, Charles W.

    2003-06-30

    Pacific Northwest National Laboratory has developed an automated system for separating Xe from air and can detect the following radioxenon isotopes, 131mXe, 133mXe, 133Xe, and 135Xe. This report details the techniques used to generate the various radioxenon isotopes that are used for the calibration of the detector as well as other isotopes that have the potential to interfere with the fission produced radioxenon isotopes. Fission production is covered first using highly enriched uranium followed by a description and results from an experiment to produce radioxenon isotopes from neutron activation of ambient xenon.

  4. ISOTOPE CONVERSION DEVICE

    DOEpatents

    Wigner, E.P.; Young, G.J.; Ohlinger, L.A.

    1957-12-01

    This patent relates to nuclear reactors of tbe type utilizing a liquid fuel and designed to convert a non-thermally fissionable isotope to a thermally fissionable isotope by neutron absorption. A tank containing a reactive composition of a thermally fissionable isotope dispersed in a liquid moderator is disposed within an outer tank containing a slurry of a non-thermally fissionable isotope convertible to a thermally fissionable isotope by neutron absorption. A control rod is used to control the chain reaction in the reactive composition and means are provided for circulating and cooling the reactive composition and slurry in separate circuits.

  5. Highly enriched isotope samples of uranium and transuranium elements for scientific investigation

    NASA Astrophysics Data System (ADS)

    Vesnovskii, Stanislav P.; Polynov, Vladimir N.; Danilin, Lev. D.

    1992-02-01

    The paper describes the production of highly enriched isotopes of uranium, plutonium, americium and curium by electromagnetic separation for scientific and applied researches in physics, chemistry, geology, medicine, biology and other fields. Using the equipment described, the isotopes are produced in quantities sufficient to set up nuclear physical experiments, to produce nuclear reference materials and standard sources for calibration of radiometrical and mass spectrometrical equipment, in radionuclide metrology, etc. For the following isotopes the indicated degrees of isotopic enrichment were achieved: 233U - 99.97%; 235U - 99.97%; 236U - 98.0%; 238U - 99.997%; 238Pu - 99.6%; 239Pu - 99.9977%; 240Pu - 99.9-100%; 241Pu - 96.998%; 242Pu - 97.8-99.96%; 244Pu - 96.7%; 241Am - 99.6%; 242Am - 73.6%; 243Am - 99.2-99.94%; 243Cm - 99.99%; 245Cm - 99.998%; 246Cm - 99.8%; 247Cm - 90%; 248Cm - 97%. Methods for preparing layers of highly enriched isotopes on various substances are presented: - electrochemical deposition of transuranic elements from aqueous-organic and organic media and vacuum spraying: - the method of foil and coating formation via compounds in the vapour phase; - the method of fabrication of layers of transuranic elements on superthin (1-2 μm) metal substrates with additional isolating polymer-metal coatings (0.2-0.4 μm), that substantially decrease material transfer from the active layer and increase safety of product handling.

  6. The structures of CyMe4-BTBP complexes of americium(iii) and europium(iii) in solvents used in solvent extraction, explaining their separation properties.

    PubMed

    Ekberg, Christian; Löfström-Engdahl, Elin; Aneheim, Emma; Foreman, Mark R StJ; Geist, Andreas; Lundberg, Daniel; Denecke, Melissa; Persson, Ingmar

    2015-11-14

    Separation of trivalent actinoid (An(iii)) and lanthanoid (Ln(iii)) ions is extremely challenging due to their similar ionic radii and chemical properties. Poly-aromatic nitrogen compounds acting as tetradentate chelating ligands to the metal ions in the extraction, have the ability to sufficiently separate An(iii) from Ln(iii). One of these compounds, 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzol[1,2,4]triazin-3-yl)[2,2]bipyridine, CyMe4-BTBP, has proven to be resistant towards acidic environments and strong radiation from radioactive decomposition. EXAFS studies of the dicomplexes of CyMe4-BTBP with americium(iii) and europium(iii) in nitrobenzene, cyclohexanone, 1-hexanol, 1-octanol and malonamide (DMDOHEMA) in 1-octanol have been carried out to get a deeper understanding of the parameters responsible for the separation. The predominating complexes independent of solvent used are [Am(CyMe4-BTBP)2(NO3)](2+) and [Eu(CyMe4-BTBP)2](3+), respectively, which are present as outer-sphere ion-pairs with nitrate ions in the studied solvents with low relative permittivity. The presence of a nitrate ion in the first coordination sphere of the americium(iii) complex compensates the charge density of the complex considerably in comparison when only outer-sphere ion-pairs are formed as for the [Eu(CyMe4-BTBP)2](3+) complex. The stability and solubility of a complex in a solvent with low relative permittivity increase with decreasing charge density. The [Am(CyMe4-BTBP)2(NO3)](2+) complex will therefore be increasingly soluble and stabilized over the [Eu(CyMe4-BTBP)2](3+) complex in solvents with decreasing relative permittivity of the solvent. The separation of americium(iii) from europium(iii) with CyMe4-BTBP as extraction agent will increase with decreasing relative permittivity of the solvent, and thereby also with decreasing solubility of CyMe4-BTBP. The choice of solvent is therefore a balance of a high separation factor and sufficient solubility of the CyMe4-BTBP

  7. On the stoichiometry and stability of americium(III) complexes with a hydrophilic SO3-Ph-BTP ligand, studied by liquid-liquid extraction.

    PubMed

    Steczek, Łukasz; Rejnis, Magdalena; Narbutt, Jerzy; Charbonnel, Marie-Christine; Moisy, Philippe

    1:1 and 1:2 complexes of americium(III) with a hydrophilic anionic SO3-Ph-BTP(4-) ligand were detected in acidic aqueous nitrate solutions by a solvent extraction method. The determined conditional stability constants of these complexes, logβ1 = 4.35 ± 0.07 and logβ2 = 7.67 ± 0.06, related to 1 M aqueous solutions, are much lower than the literature values for the analogous curium species, determined by TRLFS in very dilute aqueous solutions. There is also no evidence for the existence of the 1:3 Am(3+) complex similar to the reported curium(III) complex. A hypothesis has been formulated to explain these discrepancies. It suggests the necessity to carefully check the equilibria in each phase of solvent extraction systems containing two competing ligands-lipophilic and hydrophilic.

  8. Americium-241 Decorporation Model

    DTIC Science & Technology

    2014-10-01

    levels of exposure are required to reach doses that will induce acute effects in the lung such as radiation pneumonitis and fibrosis . The I50...compartments over time with and without treatment, excretion rates, and radiation doses to critical organs. Calculations from the model may be used to...foot2 (moment of inertia) 4.214 011 x E – 2 kilogram-meter2 (kg*m2) pound-mass/foot3 1.601 846 x E + 1 kilogram/m3 (kg/m3) rad ( radiation absorbed

  9. Hybrid isotope separation scheme

    DOEpatents

    Maya, J.

    1991-06-18

    A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus. 2 figures.

  10. Hybrid isotope separation scheme

    DOEpatents

    Maya, Jakob

    1991-01-01

    A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus.

  11. HYDROGEN ISOTOPE TARGETS

    DOEpatents

    Ashley, R.W.

    1958-08-12

    The design of targets for use in the investigation of nuclear reactions of hydrogen isotopes by bombardment with accelerated particles is described. The target con struction eomprises a backing disc of a metal selected from the group consisting of molybdenunn and tungsten, a eoating of condensed titaniunn on the dise, and a hydrogen isotope selected from the group consisting of deuterium and tritium absorbed in the coatiag. The proeess for preparing these hydrogen isotope targets is described.

  12. Discovery of the krypton isotopes

    SciTech Connect

    Heim, M.; Fritsch, A.; Schuh, A.; Shore, A.; Thoennessen, M.

    2010-07-15

    Thirty-two krypton isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  13. Intracellular Cadmium Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  14. (Carbon isotope fractionation inplants)

    SciTech Connect

    O'Leary, M.H.

    1990-01-01

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  15. Laser isotope separation

    DOEpatents

    Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.

    1975-11-26

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  16. Photochemical isotope separation

    DOEpatents

    Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

    1987-04-28

    A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

  17. Laser isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Boyer, Keith; Greiner, Norman R.

    1988-01-01

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  18. Photochemical isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1987-01-01

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  19. Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium-Plutonium-Americium U0.750Pu0.246Am0.004O2-x Mixed Oxides.

    PubMed

    Vauchy, Romain; Belin, Renaud C; Robisson, Anne-Charlotte; Lebreton, Florent; Aufore, Laurence; Scheinost, Andreas C; Martin, Philippe M

    2016-03-07

    Innovative americium-bearing uranium-plutonium mixed oxides U1-yPuyO2-x are envisioned as nuclear fuel for sodium-cooled fast neutron reactors (SFRs). The oxygen-to-metal (O/M) ratio, directly related to the oxidation state of cations, affects many of the fuel properties. Thus, a thorough knowledge of its variation with the sintering conditions is essential. The aim of this work is to follow the oxidation state of uranium, plutonium, and americium, and so the O/M ratio, in U0.750Pu0.246Am0.004O2-x samples sintered for 4 h at 2023 K in various Ar + 5% H2 + z vpm H2O (z = ∼ 15, ∼ 90, and ∼ 200) gas mixtures. The O/M ratios were determined by gravimetry, XAS, and XRD and evidenced a partial oxidation of the samples at room temperature. Finally, by comparing XANES and EXAFS results to that of a previous study, we demonstrate that the presence of uranium does not influence the interactions between americium and plutonium and that the differences in the O/M ratio between the investigated conditions is controlled by the reduction of plutonium. We also discuss the role of the homogeneity of cation distribution, as determined by EPMA, on the mechanisms involved in the reduction process.

  20. Meteoritic Sulfur Isotopic Analysis

    NASA Technical Reports Server (NTRS)

    Thiemens, Mark H.

    1996-01-01

    Funds were requested to continue our program in meteoritic sulfur isotopic analysis. We have recently detected a potential nucleosynthetic sulfur isotopic anomaly. We will search for potential carriers. The documentation of bulk systematics and the possible relation to nebular chemistry and oxygen isotopes will be explored. Analytical techniques for delta(sup 33), delta(sup 34)S, delta(sup 36)S isotopic analysis were improved. Analysis of sub milligram samples is now possible. A possible relation between sulfur isotopes and oxygen was detected, with similar group systematics noted, particularly in the case of aubrites, ureilites and entstatite chondrites. A possible nucleosynthetic excess S-33 has been noted in bulk ureilites and an oldhamite separate from Norton County. High energy proton (approximately 1 GeV) bombardments of iron foils were done to experimentally determine S-33, S-36 spallogenic yields for quantitation of isotopic measurements in iron meteorites. Techniques for measurement of mineral separates were perfected and an analysis program initiated. The systematic behavior of bulk sulfur isotopes will continue to be explored.

  1. Isotopically controlled semiconductors

    SciTech Connect

    Haller, Eugene E.

    2006-06-19

    The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

  2. ISOTOPE SEPARATING APPARATUS

    DOEpatents

    Kudravetz, M.K.; Greene, H.B.

    1958-09-16

    This patent relates to control systems for a calutron and, in particular, describes an electro-mechanical system for interrupting the collection of charged particles when the ratio between the two isotopes being receivcd deviates from a predetermined value. One embodiment of the invention includes means responsive to the ratio between two isotopes being received for opening a normally closed shutter over the receiver entrance when the isotope ratio is the desired value. In another form of the invention the collection operation is interrupted by changing the beam accelerating voltage to deflect the ion beam away from the receiver.

  3. Isotopically controlled semiconductors

    SciTech Connect

    Haller, E.E.

    2004-11-15

    A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

  4. Perchlorate Isotope Forensics

    SciTech Connect

    Bohlke, J. K.; Sturchio, N. C.; Gu, Baohua; Horita, Juske; Brown, Gilbert M; Jackson, W. Andrew; Batista, Jacimaria

    2006-01-01

    Perchlorate has been detected recently in a variety of soils, waters, plants, and food products at levels that may be detrimental to human health. These discoveries have generated considerable interest in perchlorate source identification. In this study, comprehensive stable isotope analyses ({sup 37}Cl/{sup 35}Cl and {sup 18}O/{sup 17}O/{sup 16}O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. In addition, isotopic analyses of perchlorate extracted from groundwater and surface water demonstrate the feasibility of identifying perchlorate sources in contaminated environments on the basis of this technique. Both natural and synthetic sources of perchlorate have been identified in water samples from some perchlorate occurrences in the United States by the isotopic method.

  5. Perchlorate isotope forensics

    USGS Publications Warehouse

    Böhlke, J.K.; Sturchio, N.C.; Gu, B.; Horita, J.; Brown, G.M.; Jackson, W.A.; Batista, J.; Hatzinger, P.B.

    2005-01-01

    Perchlorate has been detected recently in a variety of soils, waters, plants, and food products at levels that may be detrimental to human health. These discoveries have generated considerable interest in perchlorate source identification. In this study, comprehensive stable isotope analyses ( 37Cl/35Cl and 18O/17O/ 16O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. In addition, isotopic analyses of perchlorate extracted from groundwater and surface water demonstrate the feasibility of identifying perchlorate sources in contaminated environments on the basis of this technique. Both natural and synthetic sources of perchlorate have been identified in water samples from some perchlorate occurrences in the United States by the isotopic method. ?? 2005 American Chemical Society.

  6. Stable isotopes in mineralogy

    USGS Publications Warehouse

    O'Neil, J.R.

    1977-01-01

    Stable isotope fractionations between minerals are functions of the fundamental vibrational frequencies of the minerals and therefore bear on several topics of mineralogical interest. Isotopic compositions of the elements H, C, O, Si, and S can now be determined routinely in almost any mineral. A summary has been made of both published and new results of laboratory investigations, analyses of natural materials, and theoretical considerations which bear on the importance of temperature, pressure, chemical composition and crystal structure to the isotopic properties of minerals. It is shown that stable isotope studies can sometimes provide evidence for elucidating details of crystal structure and can be a powerful tool for use in tracing the reaction paths of mineralogical reactions. ?? 1977 Springer-Verlag.

  7. Americium-241 integral radiative capture cross section in over-moderated neutron spectrum from pile oscillator measurements in the Minerve reactor

    NASA Astrophysics Data System (ADS)

    Geslot, Benoit; Gruel, Adrien; Ros, Paul; Blaise, Patrick; Leconte, Pierre; Noguere, Gilles; Mathieu, Ludovic; Villamarin, David; Becares, Vicente; Plompen, Arjan; Kopecky, Stefan; Schillebeeckx, Peter

    2017-09-01

    An experimental program, called AMSTRAMGRAM, was recently conducted in the Minerve low power reactor operated by CEA Cadarache within the frame of the CHANDA initiative (Solving CHAllenges in Nuclear Data). Its aim was to measure the integral capture cross section of 241Am in the thermal domain. Motivation of this work is driven by large differences in this actinide thermal point reported by major nuclear data libraries. The AMSTRAMGRAM experiment, that made use of well characterized EC-JRC americium samples, was based on the oscillation technique commonly implemented in the Minerve reactor. First results are presented and discussed in this article. A preliminary calculation scheme was used to compare measured and calculated results. It is shown that this work confirms a bias previously observed with JEFF-3.1.1 (C/E-1 = -10.5 ± 2%). On the opposite, the experiment is in close agreement with 241Am thermal point reported in JEFF-3.2 (C/E-1 = 0.5 ± 2%).

  8. Characterization of pentavalent and hexavalent americium complexes in nitric acid using X-ray absorption fine structure spectroscopy and first-principles modeling

    SciTech Connect

    Riddle, Catherine; Czerwinski, Kenneth; Kim, Eunja; Paviet, Patricia; Weck, Philippe; Poineau, Frederic; Conradson, Steven

    2016-01-18

    We studied the speciation of pentavalent and hexavalent americium (Am) complexes in nitric acidicby X-ray absorption fine structure spectroscopy (XAFS), UV-visible spectroscopy, and density functional theory (DFT). Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) results were consistent with the presence of a mixture of AmO2+ and AmO22+ with only a small amount AmO2 present. The resulting average bond distances we found were 1.71 Å for Am=O and 2.44 Å for Am-O. All-electron scalar relativistic calculations were also carried out using DFT to predict the equilibrium geometries and properties of the AmO2+ and AmO22+ aquo complexes. Calculated bond distances for the Am(VI) complex are in reasonable agreement with EXAFS data and the computed energy gaps between frontier molecular orbitals suggest a slightly higher kinetic stability and chemical hardness of Am(VI) compared to Am(V).

  9. Characterization of pentavalent and hexavalent americium complexes in nitric acid using X-ray absorption fine structure spectroscopy and first-principles modeling

    DOE PAGES

    Riddle, Catherine; Czerwinski, Kenneth; Kim, Eunja; ...

    2016-01-18

    We studied the speciation of pentavalent and hexavalent americium (Am) complexes in nitric acidicby X-ray absorption fine structure spectroscopy (XAFS), UV-visible spectroscopy, and density functional theory (DFT). Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) results were consistent with the presence of a mixture of AmO2+ and AmO22+ with only a small amount AmO2 present. The resulting average bond distances we found were 1.71 Å for Am=O and 2.44 Å for Am-O. All-electron scalar relativistic calculations were also carried out using DFT to predict the equilibrium geometries and properties of the AmO2+ and AmO22+ aquomore » complexes. Calculated bond distances for the Am(VI) complex are in reasonable agreement with EXAFS data and the computed energy gaps between frontier molecular orbitals suggest a slightly higher kinetic stability and chemical hardness of Am(VI) compared to Am(V).« less

  10. Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution.

    SciTech Connect

    Bruce J. Mincher; Nicholas C. Schmitt

    2015-03-01

    The peroxydisulfate anion has long been used for the preparation of hexavalent americium (AmVI) from the normally stable AmIII valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (AmV) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of AmVI. Incomplete oxidation would be expected to leave residual AmIII, or to produce AmV in treated solutions. However, until recently, the use of peroxydisulfate as an AmV reagent has not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative AmV was prepared in an acidic solution and the UV/Vis extinction coefficients of the AmV 513 nm peak were measured over a range of nitric acid concentrations. The utility of AmV for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.

  11. Diluent and extractant effects on the enthalpy of extraction of uranium(VI) and americium(III) nitrates by trialkyl phosphates

    SciTech Connect

    Srinivasan, T.G.; Vasudeva Rao, P.R.; Sood, D.D.

    1998-11-01

    The effect of various diluents such as n-hexane, n-heptane n-octane, isooctane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-hexadecane, cyclohexane, benzene, toluene, p-xylene, mesitylene and o-dichlorobenzene on the enthalpy of extraction of uranyl nitrate by tri-n-amyl phosphate (TAP) over the temperature range 283 K--333 K has been studied. The results indicate that the enthalpy of extraction does not vary significantly with the diluents studied. Also enthalpies of extraction of uranyl nitrate and americium(III) nitrate by neutral organo phosphorous extractants such as tri-n-butyl phosphate (TBP), tri-n-amyl phosphate (TAP), tri-sec-butyl phosphate (TsBP), tri-isoamyl phosphate (TiAP) and tri-n-hexyl phosphate (THP) have been studied. An attempt has been made to explain the trends, on the basis of the nature of the solvate formed and the different terms which contribute to the overall enthalpy change.

  12. The design of a multisource americium-beryllium (Am-Be) neutron irradiation facility using MCNP for the neutronic performance calculation.

    PubMed

    Sogbadji, R B M; Abrefah, R G; Nyarko, B J B; Akaho, E H K; Odoi, H C; Attakorah-Birinkorang, S

    2014-08-01

    The americium-beryllium neutron irradiation facility at the National Nuclear Research Institute (NNRI), Ghana, was re-designed with four 20 Ci sources using Monte Carlo N-Particle (MCNP) code to investigate the maximum amount of flux that is produced by the combined sources. The results were compared with a single source Am-Be irradiation facility. The main objective was to enable us to harness the maximum amount of flux for the optimization of neutron activation analysis and to enable smaller sample sized samples to be irradiated. Using MCNP for the design construction and neutronic performance calculation, it was realized that the single-source Am-Be design produced a thermal neutron flux of (1.8±0.0007)×10(6) n/cm(2)s and the four-source Am-Be design produced a thermal neutron flux of (5.4±0.0007)×10(6) n/cm(2)s which is a factor of 3.5 fold increase compared to the single-source Am-Be design. The criticality effective, k(eff), of the single-source and the four-source Am-Be designs were found to be 0.00115±0.0008 and 0.00143±0.0008, respectively.

  13. Americium(III) capture using phosphonic acid-functionalized silicas with different mesoporous morphologies: adsorption behavior study and mechanism investigation by EXAFS/XPS.

    PubMed

    Zhang, Wen; He, Xihong; Ye, Gang; Yi, Rong; Chen, Jing

    2014-06-17

    Efficient capture of highly toxic radionuclides with long half-lives such as Americium-241 is crucial to prevent radionuclides from diffusing into the biosphere. To reach this purpose, three different types of mesoporous silicas functionalized with phosphonic acid ligands (SBA-POH, MCM-POH, and BPMO-POH) were synthesized via a facile procedure. The structure, surface chemistry, and micromorphology of the materials were fully characterized by (31)P/(13)C/(29)Si MAS NMR, XPS, and XRD analysis. Efficient adsorption of Am(III) was realized with a fast rate to reach equilibrium (within 10 min). Influences including structural parameters and functionalization degree on the adsorption behavior were investigated. Slope analysis of the equilibrium data suggested that the coordination with Am(III) involved the exchange of three protons. Moreover, extended X-ray absorption fine structure (EXAFS) analysis, in combination with XPS survey, was employed for an in-depth probe into the binding mechanism by using Eu(III) as a simulant due to its similar coordination behavior and benign property. The results showed three phosphonic acid ligands were coordinated to Eu(III) in bidentate fashion, and Eu(P(O)O)3(H2O) species were formed with the Eu-O coordination number of 7. These phosphonic acid-functionalized mesoporous silicas should be promising for the treatment of Am-containing radioactive liquid waste.

  14. Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution

    SciTech Connect

    Mincher, Bruce J.; Schmitt, Nicholas C.; Schuetz, Brian K.; Shehee, Thomas C.; Hobbs, David T.

    2015-03-11

    The peroxydisulfate anion has long been used for the preparation of hexavalent americium (AmVI) from the normally stable AmIII valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (AmV) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of AmVI. Incomplete oxidation would be expected to leave residual AmIII, or to produce AmV in treated solutions. However, until recently, the use of peroxydisulfate as an AmV reagent has not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative AmV was prepared in an acidic solution and the UV/Vis extinction coefficients of the AmV 513 nm peak were measured over a range of nitric acid concentrations. Furthermore, the utility of AmV for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.

  15. Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution

    DOE PAGES

    Mincher, Bruce J.; Schmitt, Nicholas C.; Schuetz, Brian K.; ...

    2015-03-11

    The peroxydisulfate anion has long been used for the preparation of hexavalent americium (AmVI) from the normally stable AmIII valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (AmV) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of AmVI. Incomplete oxidation would be expected to leave residual AmIII, or to produce AmV in treated solutions. However, until recently, the use of peroxydisulfate as an AmV reagent hasmore » not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative AmV was prepared in an acidic solution and the UV/Vis extinction coefficients of the AmV 513 nm peak were measured over a range of nitric acid concentrations. Furthermore, the utility of AmV for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.« less

  16. Fertilizer nitrogen isotope signatures.

    PubMed

    Bateman, Alison S; Kelly, Simon D

    2007-09-01

    There has been considerable recent interest in the potential application of nitrogen isotope analysis in discriminating between organically and conventionally grown crops. A prerequisite of this approach is that there is a difference in the nitrogen isotope compositions of the fertilizers used in organic and conventional agriculture. We report new measurements of delta15N values for synthetic nitrogen fertilizers and present a compilation of the new data with existing literature nitrogen isotope data. Nitrogen isotope values for fertilizers that may be permitted in organic cultivation systems are also reported (manures, composts, bloodmeal, bonemeal, hoof and horn, fishmeal and seaweed based fertilizers). The delta15N values of the synthetic fertilizers in the compiled dataset fall within a narrow range close to 0 per thousand with 80% of samples lying between-2 and 2 per thousand and 98.5% of the data having delta15N values of less than 4 per thousand (mean=0.2 per thousand n=153). The fertilizers that may be permitted in organic systems have a higher mean delta15N value of 8.5 per thousand and exhibit a broader range in delta15N values from 0.6 to 36.7 per thousand (n=83). The possible application of the nitrogen isotope approach in discriminating between organically and conventionally grown crops is discussed in light of the fertilizer data presented here and with regard to other factors that are also important in determining crop nitrogen isotope values.

  17. Laser Ablation Molecular Isotopic Spectrometry: Strontium and its isotopes

    NASA Astrophysics Data System (ADS)

    Mao, Xianglei; Bol'shakov, Alexander A.; Choi, Inhee; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman; Russo, Richard E.

    2011-11-01

    The experimental details are reported of Laser Ablation Molecular Isotopic Spectrometry (LAMIS) and its application for performing optical isotopic analysis of solid strontium-containing samples in ambient atmospheric air at normal pressure. The LAMIS detection method is described for strontium isotopes from samples of various chemical and isotopic compositions. The results demonstrate spectrally resolved measurements of the three individual 86Sr, 87Sr, and 88Sr isotopes that are quantified using multivariate calibration of spectra. The observed isotopic shifts are consistent with those calculated theoretically. The measured spectra of diatomic oxide and halides of strontium generated in laser ablation plasmas demonstrate the isotopic resolution and capability of LAMIS. In particular, emission spectra of SrO and SrF molecular radicals provided clean and well resolved spectral signatures for the naturally occurring strontium isotopes. A possibility is discussed of using LAMIS of strontium isotopes for radiogenic age determination.

  18. The isotopic distribution conundrum.

    PubMed

    Valkenborg, Dirk; Mertens, Inge; Lemière, Filip; Witters, Erwin; Burzykowski, Tomasz

    2012-01-01

    Although access to high-resolution mass spectrometry (MS), especially in the field of biomolecular MS, is becoming readily available due to recent advances in MS technology, the accompanied information on isotopic distribution in high-resolution spectra is not used at its full potential, mainly because of lack of knowledge and/or awareness. In this review, we give an insight into the practical problems related to calculating the isotopic distribution for large biomolecules, and present an overview of methods for the calculation of the isotopic distribution. We discuss the key events that triggered the development of various algorithms and explain the rationale of how and why the various isotopic-distribution calculations were performed. The review is focused around the developmental stages as briefly outlined below, starting with the first observation of an isotopic distribution. The observations of Beynon in the field of organic MS that chlorine appeared in a mass spectrum as two variants with odds 3:1 lie at the basis of the first wave of algorithms for the calculation of the isotopic distribution, based on the atomic composition of a molecule. From here on, we explain why more complex biomolecules such as peptides exhibit a highly complex isotope pattern when assayed by MS, and we discuss how combinatorial difficulties complicate the calculation of the isotopic distribution on computers. For this purpose, we highlight three methods, which were introduced in the 1980s. These are the stepwise procedure introduced by Kubinyi, the polynomial expansion from Brownawell and Fillippo, and the multinomial expansion from Yergey. The next development was instigated by Rockwood, who suggested to decompose the isotopic distribution in terms of their nucleon count instead of the exact mass. In this respect, we could claim that the term "aggregated" isotopic distribution is more appropriate. Due to the simplification of the isotopic distribution to its aggregated counterpart

  19. Oxygen Isotopes in Meteorites

    NASA Astrophysics Data System (ADS)

    Clayton, R. N.

    2003-12-01

    Oxygen isotope abundance variations in meteorites are very useful in elucidating chemical and physical processes that occurred during the formation of the solar system (Clayton, 1993). On Earth, the mean abundances of the three stable isotopes are 16O: 99.76%, 17O: 0.039%, and 18O: 0.202%. It is conventional to express variations in abundances of the isotopes in terms of isotopic ratios, relative to an arbitrary standard, called SMOW (for standard mean ocean water), as follows:The isotopic composition of any sample can then be represented by one point on a "three-isotope plot," a graph of δ17O versus δ18O. It will be seen that such plots are invaluable in interpreting meteoritic data. Figure 1 shows schematically the effect of various processes on an initial composition at the center of the diagram. Almost all terrestrial materials lie along a "fractionation" trend; most meteoritic materials lie near a line of "16O addition" (or subtraction). (4K)Figure 1. Schematic representation of various isotopic processes shown on an oxygen three-isotope plot. Almost all terrestrial materials plot along a line of "fractionation"; most primitive meteoritic materials plot near a line of "16O addition." The three isotopes of oxygen are produced by nucleosynthesis in stars, but by different nuclear processes in different stellar environments. The principal isotope, 16O, is a primary isotope (capable of being produced from hydrogen and helium alone), formed in massive stars (>10 solar masses), and ejected by supernova explosions. The two rare isotopes are secondary nuclei (produced in stars from nuclei formed in an earlier generation of stars), with 17O coming primarily from low- and intermediate-mass stars (<8 solar masses), and 18O coming primarily from high-mass stars (Prantzos et al., 1996). These differences in type of stellar source result in large observable variations in stellar isotopic abundances as functions of age, size, metallicity, and galactic location ( Prantzos

  20. Physicochemical isotope anomalies

    SciTech Connect

    Esat, T.M.

    1988-06-01

    Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {sup 26}Mg excesses and mass dependent fractionation. It is possible that the {sup 26}Mg excesses in interplanetary dust is related to sputtering by energetic solar-wind particles. The implication if the laboratory distillation and sputtering effects are discussed and contrasted with the anomalies in meteoritic inclusions the other extraterrestrial materials the authors have access to.

  1. Assessment of americium and curium transmutation in magnesia based targets in different spectral zones of an experimental accelerator driven system

    NASA Astrophysics Data System (ADS)

    Haeck, W.; Malambu, E.; Sobolev, V. P.; Aït Abderrahim, H.

    2006-06-01

    The potential to incinerate minor actinides (MA) in a sub-critical accelerator-driven system (ADS) is a subject of study in several countries where nuclear power plants are present. The performance of the MYRRHA experimental ADS, as to the transmutation of Am and Cm in the inert matrix fuel (IMF) samples consisting of 40 vol.% (Cm0.1Am0.5Pu0.4)O1.88 fuel and 60 vol.% MgO matrix with a density of 6.077 g cm-3 in three various spectrum regions, were analysed at the belgian nuclear research centre SCK · CEN. The irradiation period of 810 effective full power days (EFPD) followed by a storage period of 2 years was considered. The ALEPH code system currently under development at SCK · CEN was used to carry out this study. The total amount of MA is shown to decrease in all three considered cases. For Am, the decrease is the largest in the reflector (89% decrease) but at the cost of a net Cm production (92% increase). In the two other positions (inside the core region), 20-30% of Am has disappeared but with a lower production of Cm (between 7% and 11%). In the reflector, a significant build-up of long-lived 245Cm, 246Cm, 247Cm and 248Cm was also observed while the production of these isotopes is 10-1000 times smaller in the core. The reduction of the Pu content is also the highest in the reflector position (41%). In the other positions the incinerated amount of Pu is much smaller: 1-5%.

  2. Separation of sulfur isotopes

    DOEpatents

    DeWitt, Robert; Jepson, Bernhart E.; Schwind, Roger A.

    1976-06-22

    Sulfur isotopes are continuously separated and enriched using a closed loop reflux system wherein sulfur dioxide (SO.sub.2) is reacted with sodium hydroxide (NaOH) or the like to form sodium hydrogen sulfite (NaHSO.sub.3). Heavier sulfur isotopes are preferentially attracted to the NaHSO.sub.3, and subsequently reacted with sulfuric acid (H.sub.2 SO.sub.4) forming sodium hydrogen sulfate (NaHSO.sub.4) and SO.sub.2 gas which contains increased concentrations of the heavier sulfur isotopes. This heavy isotope enriched SO.sub.2 gas is subsequently separated and the NaHSO.sub.4 is reacted with NaOH to form sodium sulfate (Na.sub.2 SO.sub.4) which is subsequently decomposed in an electrodialysis unit to form the NaOH and H.sub.2 SO.sub.4 components which are used in the aforesaid reactions thereby effecting sulfur isotope separation and enrichment without objectionable loss of feed materials.

  3. Transportation of medical isotopes

    SciTech Connect

    Nielsen, D.L.

    1997-11-19

    A Draft Technical Information Document (HNF-1855) is being prepared to evaluate proposed interim tritium and medical isotope production at the Fast Flux Test Facility (FFTF). This assessment examines the potential health and safety impacts of transportation operations associated with the production of medical isotopes. Incident-free and accidental impacts are assessed using bounding source terms for the shipment of nonradiological target materials to the Hanford Site, the shipment of irradiated targets from the FFTF to the 325 Building, and the shipment of medical isotope products from the 325 Building to medical distributors. The health and safety consequences to workers and the public from the incident-free transportation of targets and isotope products would be within acceptable levels. For transportation accidents, risks to works and the public also would be within acceptable levels. This assessment is based on best information available at this time. As the medical isotope program matures, this analysis will be revised, if necessary, to support development of a final revision to the Technical Information Document.

  4. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    PubMed

    Yeung, Laurence Y; Ash, Jeanine L; Young, Edward D

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling.

  5. Isotope separation apparatus

    DOEpatents

    Arnush, Donald; MacKenzie, Kenneth R.; Wuerker, Ralph F.

    1980-01-01

    Isotope separation apparatus consisting of a plurality of cells disposed adjacent to each other in an evacuated container. A common magnetic field is established extending through all of the cells. A source of energetic electrons at one end of the container generates electrons which pass through the cells along the magnetic field lines. Each cell includes an array of collector plates arranged in parallel or in tandem within a common magnetic field. Sets of collector plates are disposed adjacent to each other in each cell. Means are provided for differentially energizing ions of a desired isotope by applying energy at the cyclotron resonant frequency of the desired isotope. As a result, the energized desired ions are preferentially collected by the collector plates.

  6. Atomic Weights and Isotopic Compositions

    National Institute of Standards and Technology Data Gateway

    SRD 144 Atomic Weights and Isotopic Compositions (Web, free access)   The atomic weights are available for elements 1 through 111, and isotopic compositions or abundances are given when appropriate.

  7. High Atomic Weight Isotope Separator.

    DTIC Science & Technology

    This patent discusses a method of separating one isotopic species of a given element from a mixture. Collisionless plasma instabilities slow down the ions and oppositely charged electrodes separate the isotopes.

  8. Complexation of lanthanides(III), americium(III), and uranium(VI) with bitopic N,O ligands: an experimental and theoretical study.

    PubMed

    Marie, Cécile; Miguirditchian, Manuel; Guillaumont, Dominique; Tosseng, Arnaud; Berthon, Claude; Guilbaud, Philippe; Duvail, Magali; Bisson, Julia; Guillaneux, Denis; Pipelier, Muriel; Dubreuil, Didier

    2011-07-18

    New functionalized terpyridine-diamide ligands were recently developed for the group actinide separation by solvent extraction. In order to acquire a better understanding of their coordination mode in solution, protonation and complexation of lanthanides(III), americium(III), and uranium(VI) with these bitopic N,O-bearing ligands were studied in homogeneous methanol/water conditions by experimental and theoretical approaches. UV-visible spectrophotometry was used to determine the protonation and stability constants of te-tpyda and dedp-tpyda. The conformations of free and protonated forms of te-tpyda were investigated using NMR and theoretical calculations. The introduction of amide functional groups on the terpyridine moiety improved the extracting properties of these new ligands by lowering their basicity and enhancing the stability of the corresponding 1:1 complexes with lanthanides(III). Coordination of these ligands was studied by density functional theory and molecular dynamics calculations, especially to evaluate potential participation of hard oxygen and soft nitrogen atoms in actinide coordination and to correlate with their affinity and selectivity. Two predominant inner-sphere coordination modes were found from the calculations: one mode where the cation is coordinated by the nitrogen atoms of the cavity and by the amide oxygen atoms and the other mode where the cation is only coordinated by the two amide oxygen atoms and by solvent molecules. Further simulations and analysis of UV-visible spectra using both coordination modes indicate that inner-sphere coordination with direct complexation of the three nitrogen and two oxygen atoms to the cation leads to the most likely species in a methanol/water solution.

  9. DEEP WATER ISOTOPIC CURRENT ANALYZER

    DOEpatents

    Johnston, W.H.

    1964-04-21

    A deepwater isotopic current analyzer, which employs radioactive isotopes for measurement of ocean currents at various levels beneath the sea, is described. The apparatus, which can determine the direction and velocity of liquid currents, comprises a shaft having a plurality of radiation detectors extending equidistant radially therefrom, means for releasing radioactive isotopes from the shaft, and means for determining the time required for the isotope to reach a particular detector. (AEC)

  10. Method for separating boron isotopes

    DOEpatents

    Rockwood, Stephen D.

    1978-01-01

    A method of separating boron isotopes .sup.10 B and .sup.11 B by laser-induced selective excitation and photodissociation of BCl.sub.3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub.3, thus effecting the desired separation of the boron isotopes.

  11. Uranium Isotopic Analysis with the FRAM Isotopic Analysis Code

    SciTech Connect

    Duc T. Vo; Thomas E. Sampson

    1999-05-01

    FRAM is the acronym for Fixed-energy Response-function Analysis with Multiple efficiency. This software was developed at Los Alamos National Laboratory originally for plutonium isotopic analysis. Later, it was adapted for uranium isotopic analysis in addition to plutonium. It is a code based on a self-calibration using several gamma-ray peaks for determining the isotopic ratios. The versatile-parameter database structure governs all facets of the data analysis. User editing of the parameter sets allows great flexibility in handling data with different isotopic distributions, interfering isotopes, and different acquisition parameters such as energy calibration and detector type.

  12. Forensic Stable Isotope Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  13. Sulfur isotopic data

    SciTech Connect

    Rye, R.O.

    1987-01-01

    Preliminary sulfur isotope data have been determined for samples of the Vermillion Creek coal bed and associated rocks in the Vermillion Creek basin and for samples of evaporites collected from Jurassic and Triassic formations that crop out in the nearby Uinta Mountains. The data are inconclusive, but it is likely that the sulfur in the coal was derived from the evaporites.

  14. Stable isotopic studies on chitin

    SciTech Connect

    Schimmelmann, A.

    1985-01-01

    Carbon, nitrogen, oxygen, and hydrogen stable isotope ratios of the poly-amino-sugar chitin isolated from exo-skeletons of 75 arthropod species collected in 59 locations were determined. The objectives were to understand the environmental, climatic, and biological influences on the isotope ratios and to develop a data base for interpreting isotope ratios of archaeological and fossil chitins. Measurements of stable isotope ratios in chitin isolates showed large variations which reflect intrinsic compositional and isotopic heterogeneities as well as differences caused by methods of preparation.

  15. Isotopic dependence of nuclear temperatures

    SciTech Connect

    Su Jun; Zhang Fengshou

    2011-09-15

    A systematic study of isotope temperatures has been presented for heavy-ion collisions at 600 MeV/nucleon via the isospin-dependent quantum molecular dynamics model in the company of the statistical decay model (GEMINI). We find that the isospin dependence of the isotope temperatures in multifragmentation is weak; however, this effect is still visible over a wide isotopic range. The isotope temperatures for the neutron-rich projectiles are larger than those for the neutron-poor projectiles. We also find that the isotope temperatures calculated by the model decrease with increasing nuclear mass.

  16. Determination of uranium isotopic composition and 236U content of soil samples and hot particles using inductively coupled plasma mass spectrometry.

    PubMed

    Boulyga, S F; Becker, J S

    2001-07-01

    As a result of the accident at the Chernobyl nuclear power plant (NPP) the environment was contaminated with spent nuclear fuel. The 236U isotope was used in this study to monitor the spent uranium from nuclear fallout in soil samples collected in the vicinity of the Chernobyl NPP. Nuclear track radiography was applied for the identification and extraction of hot radioactive particles from soil samples. A rapid and sensitive analytical procedure was developed for uranium isotopic ratio measurement in environmental samples based on double-focusing inductively coupled plasma mass spectrometry (DF-ICP-MS) with a MicroMist nebulizer and a direct injection high-efficiency nebulizer (DIHEN). The performance of the DF-ICP-MS with a quartz DIHEN and plasma shielded torch was studied. Overall detection efficiencies of 4 x 10(-4) and 10(-3) counts per atom were achieved for 238U in DF-ICP-QMS with the MicroMist nebulizer and DIHEN, respectively. The rate of formation of uranium hydride ions UH+/U+ was 1.2 x 10(-4) and 1.4 x 10(-4), respectively. The precision of short-term measurements of uranium isotopic ratios (n = 5) in 1 microg L(-1) NBS U-020 standard solution was 0.11% (238U/235U) and 1.4% (236U/238U) using a MicroMist nebulizer and 0.25% (235U/238U) and 1.9% (236U/P38U) using a DIHEN. The isotopic composition of all investigated Chernobyl soil samples differed from those of natural uranium; i.e. in these samples the 236U/238U ratio ranged from 10(-5) to 10(-3). Results obtained with ICP-MS, alpha- and gamma-spectrometry showed differences in the migration properties of spent uranium, plutonium, and americium. The isotopic ratio of uranium was also measured in hot particles extracted from soil samples.

  17. Water isotopes in desiccating lichens

    PubMed Central

    Cuntz, Matthias; Máguas, Cristina; Lakatos, Michael

    2009-01-01

    The stable isotopic composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in non-vascular, poikilohydric organisms such as lichens and bryophytes. To understand basic isotope exchange processes of non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrate with the isotopic composition of surrounding water vapour. A model was developed as a proof of concept that accounts for the specific water relations of these poikilohydric organisms. The approach incorporates first their variable thallus water potential and second a compartmentation of the thallus water into two isotopically distinct but connected water pools. Moreover, the results represent first steps towards the development of poikilohydric organisms as a recorder of ambient vapour isotopic composition. PMID:19888598

  18. Impact of the cation distribution homogeneity on the americium oxidation state in the U0.54Pu0.45Am0.01O2-x mixed oxide

    NASA Astrophysics Data System (ADS)

    Vauchy, Romain; Robisson, Anne-Charlotte; Martin, Philippe M.; Belin, Renaud C.; Aufore, Laurence; Scheinost, Andreas C.; Hodaj, Fiqiri

    2015-01-01

    The impact of the cation distribution homogeneity of the U0.54Pu0.45Am0.01O2-x mixed oxide on the americium oxidation state was studied by coupling X-ray diffraction (XRD), electron probe micro analysis (EPMA) and X-ray absorption spectroscopy (XAS). Oxygen-hypostoichiometric Am-bearing uranium-plutonium mixed oxide pellets were fabricated by two different co-milling based processes in order to obtain different cation distribution homogeneities. The americium was generated from β- decay of 241Pu. The XRD analysis of the obtained compounds did not reveal any structural difference between the samples. EPMA, however, revealed a high homogeneity in the cation distribution for one sample, and substantial heterogeneity of the U-Pu (so Am) distribution for the other. The difference in cation distribution was linked to a difference in Am chemistry as investigated by XAS, with Am being present at mixed +III/+IV oxidation state in the heterogeneous compound, whereas only Am(IV) was observed in the homogeneous compound. Previously reported discrepancies on Am oxidation states can hence be explained by cation distribution homogeneity effects.

  19. Iron isotope biosignatures

    NASA Technical Reports Server (NTRS)

    Beard, B. L.; Johnson, C. M.; Cox, L.; Sun, H.; Nealson, K. H.; Aguilar, C.

    1999-01-01

    The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.

  20. The oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Brown, B. Alex

    The properties of the oxygen isotopes provide diverse examples of progress made in experiments and theory. This chain of isotopes has been studied from beyond the proton drip line in 12O to beyond the neutron drip line in 25,26O. This short survey starts with the microscopic G matrix approach for 18O of Kuo and Brown in the 1960’s and shows how theory has evolved. The nuclear structure around the doubly-magic nucleus 24O is particularly simple in terms of the nuclear shell model. The nuclear structure around the doubly-magic nucleus 16O exhibits the coexistence of single-particle and collective structure.

  1. Iron isotope biosignatures.

    PubMed

    Beard, B L; Johnson, C M; Cox, L; Sun, H; Nealson, K H; Aguilar, C

    1999-09-17

    The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.

  2. New Isotope 263Hs

    SciTech Connect

    Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Dvorak, J.; Ellison, P.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Nitsche, H.

    2010-03-16

    A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].

  3. ISOTOPE SEPARATING APPARATUS CONTROL

    DOEpatents

    Barnes, S.W.

    1959-08-25

    An improved isotope separating apparatus of the electromagnetic type, commonly referred to as a calutron, is described. Improvements in detecting and maintaining optimum position and focus of the ion beam are given. The calutron collector is provided with an additional electrode insulated from and positioned between the collecting pockets. The ion beams are properly positioned and focused until the deionizing current which flows from ground to this additional electrode ts a minimum.

  4. Stable isotope laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Becker, J. F.; Yaldaei, Ramil; Mckay, Christopher P.

    1989-01-01

    Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

  5. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    SciTech Connect

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  6. Electrochemically controlled iron isotope fractionation

    NASA Astrophysics Data System (ADS)

    Black, Jay R.; Young, Edward D.; Kavner, Abby

    2010-02-01

    Variations in the stable isotope abundances of transition metals have been observed in the geologic record and trying to understand and reconstruct the physical/environmental conditions that produced these signatures is an area of active research. It is clear that changes in oxidation state lead to large fractionations of the stable isotopes of many transition metals such as iron, suggesting that transition metal stable isotope signatures could be used as a paleo-redox proxy. However, the factors contributing to these observed stable isotope variations are poorly understood. Here we investigate how the kinetics of iron redox electrochemistry generates isotope fractionation. Through a combination of electrodeposition experiments and modeling of electrochemical processes including mass-transport, we show that electron transfer reactions are the cause of a large isotope separation, while mass transport-limited supply of reactant to the electrode attenuates the observed isotopic fractionation. Furthermore, the stable isotope composition of electroplated transition metals can be tuned in the laboratory by controlling parameters such as solution chemistry, reaction overpotential, and solution convection. These methods are potentially useful for generating isotopically-marked metal surfaces for tracking and forensic purposes. In addition, our studies will help interpret stable isotope data in terms of identifying underlying electron transfer processes in laboratory and natural samples.

  7. Recovering Americium and Curium from Mark-42 Target Materials- New Processing Approaches to Enhance Separations and Integrate Waste Stream Disposition - 12228

    SciTech Connect

    Patton, Brad D.; Benker, Dennis; Collins, Emory D.; Mattus, Catherine H.; Robinson, Sharon M.; Wham, Robert M.

    2012-07-01

    Oak Ridge National Laboratory (ORNL) is investigating flowsheets to enhance processing efficiencies and to address waste streams associated with recovery of americium (Am) and curium (Cm) from Mark-42 (Mk-42) target materials stored at ORNL. The objective of this work was to identify the most effective flowsheet with which to process the 104 Mk-42 oxide capsules holding a total of 80 g of plutonium (Pu), 190 g of Cm, 480 g of Am, and 5 kg of lanthanide (Ln) oxides for the recovery and purification of the Am/Cm for future use as feedstock for heavy actinide production. Studies were also conducted to solidify the process flowsheet waste streams for disposal. ORNL is investigating flowsheets to enhance processing efficiencies and address waste streams associated with recovery of Am and Cm from Mk-42 target materials stored at ORNL. A series of small-scale runs are being performed to demonstrate an improved process to recover Am/Cm and to optimize the separations of Ln fission products from the Am/Cm constituents. The first of these runs has been completed using one of the Am/Cm/Ln oxide capsules stored at ORNL. The demonstration run showed promising results with a Ln DF of 40 for the Am/Cm product and an Am/Cm DF of 75 for the Ln product. In addition, the total losses of Am, Cm, and Ln to the waste solvents and raffinates were very low at <0.2%, 0.02%, and 0.04%, respectively. However, the Ln-actinide separation was less than desired. For future Reverse TALSPEAK demonstration runs, several parameters will be adjusted (flow rates, the ratio of scrub to strip stages, etc.) to improve the removal of Ln from the actinides. The next step will also include scale-up of the processing flowsheet to use more concentrated solutions (15 g/L Ln versus 5 g/L) and larger volumes and to recycle the HDEHP solvent. This should improve the overall processing efficiency and further reduce losses to waste streams. Studies have been performed with simulated wastes to develop solidification

  8. Laser isotope separation of erbium and other isotopes

    DOEpatents

    Haynam, Christopher A.; Worden, Earl F.

    1995-01-01

    Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of .sup.167 Er. The hyperfine structure of .sup.167 Er was used to find two three-step photoionization pathways having a common upper energy level.

  9. Laser isotope separation of erbium and other isotopes

    DOEpatents

    Haynam, C.A.; Worden, E.F.

    1995-08-22

    Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of {sup 167}Er. The hyperfine structure of {sup 167}Er was used to find two three-step photoionization pathways having a common upper energy level. 3 figs.

  10. Nickel isotopes and methanogens

    NASA Astrophysics Data System (ADS)

    Neubeck, A.; Ivarsson, M.

    2013-12-01

    Methanogens require Ni for their growth and as a consequence the microbial fractionation of Ni isotopes can be used as a biomarker for activity of methanogenic communities1. Anaerobic laboratory experiments was performed using methanogens to investigate methanogenic growth in a modified nutrient media2 with olivine Fo91 (5g/l) added as an additional mineral nutrient source and as the only H2 provider. One of the investigated methanogens showed an increased growth in the experiments with added olivine. There were also a close relationship between the mobilized Ni and the growth of the methanogen. Ni is an element that previously has been neglected in the study of fossilized microorganisms and their interaction with mineral substrates and, thus, there are no records or published data of Ni in association with microfossils. However, we have detected enrichments of Ni in fossilized microorganisms and ichno-fossils, respectively, from three separate locations. Ni is not present in the host rock in any of the samples. Thus, Ni is present in association with fossilized microorganisms from environments and more extensive analysis is required to understand the magnitude, uptake, preservation and fractionation of Ni in microfossils. In order to analyze Ni isotope fractionation from microbe-mineral interaction, we plan to use a high-resolution Laser-Ablation Time-of-Flight Mass Spectrometer (LMS)3. In situ profile ablation will provide detailed and localized data on fractionation patterns between microfossils and their host rock. Also, this technique will allow us to identify the change in Ni isotopic fractionation in rock samples caused by abiotic and biogenic processes in a faster and easier way and with less risk for contamination compared to the wet chemistry analyses of Ni isotopes. 1. Cameron, V., Vance, D., Archer, C. & House, C. H. A biomarker based on the stable isotopes of nickel. Proceedings of the National Academy of Sciences 106, 10944-10948 (2009). 2. Schn

  11. Laser Ablation Molecular Isotopic Spectrometry

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  12. Isotopic anomalies in extraterrestrial grains.

    PubMed

    Ireland, T R

    1996-03-01

    Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars.

  13. Stable isotope research pool inventory

    SciTech Connect

    Not Available

    1988-02-01

    This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high-abundance, naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56.

  14. Lunar Surface Stirling Power Systems Using Isotope Heat Sources

    NASA Technical Reports Server (NTRS)

    Schmitz, Paul C.; Penswick, L. Barry; Shaltens, Richard K.

    2010-01-01

    For many years, NASA has used the decay of plutonium-238 (Pu-238) (in the form of the General Purpose Heat Source (GPHS)) as a heat source for Radioisotope Thermoelectric Generators (RTGs), which have provided electrical power for many NASA missions. While RTGs have an impressive reliability record for the missions in which they have been used, their relatively low thermal to electric conversion efficiency and the scarcity of plutonium-238 (Pu-238) has led NASA to consider other power conversion technologies. NASA is considering returning both robotic and human missions to the lunar surface and, because of the long lunar nights (14.75 Earth days), isotope power systems are an attractive candidate to generate electrical power. NASA is currently developing the Advanced Stirling Radioisotope Generator (ASRG) as a candidate higher efficiency power system that produces greater than 160 W with two GPHS modules at the beginning of life (BOL) (32% efficiency). The ASRG uses the same Pu-238 GPHS modules, which are used in RTG, but by coupling them to a Stirling convertor provides a four-fold reduction in the number of GPHS modules. This study considers the use of americium-241 (Am-241) as a substitute for the Pu-238 in Stirling- convertor-based Radioisotope Power Systems (RPS) for power levels from tens of watts to 5 kWe. The Am-241 is used as a substitute for the Pu-238 in GPHS modules. Depending on power level, different Stirling heat input and removal systems are modeled. It was found that substituting Am-241 GPHS modules into the ASRG reduces power output by about one-fifth while maintaining approximately the same system mass. In order to obtain the nominal 160 W of electrical output of the Pu-238 ASRG requires 10 Am-241 GPHS modules. Higher power systems require changing from conductive coupling heat input and removal from the Stirling convertor to either pumped loops or heat pipes. Liquid metal pumped loops are considered as the primary heat transportation on the hot

  15. Metal Stable Isotopes in Paleoceanography

    NASA Astrophysics Data System (ADS)

    Anbar, Ariel D.; Rouxel, Olivier

    2007-05-01

    Considered esoteric only a few years ago, research into the stable isotope geochemistry of transition metals is moving into the geoscience mainstream. Although initial attention focused on the potential use of some of these nontraditional isotope systems as biosignatures, they are now emerging as powerful paleoceanographic proxies. In particular, the Fe and Mo isotope systems are providing information about changes in oxygenation and metal cycling in ancient oceans. Zn, Cu, Tl, and a number of other metals and metalloids also show promise. Here we review the basis of stable isotope fractionation as it applies to these elements, analytical considerations, and the current status and future prospects of this rapidly developing research area.

  16. Photonuclear Production of Medical Isotopes

    NASA Astrophysics Data System (ADS)

    Weinandt, Nick

    2011-10-01

    Every year, more than 20 million people in the United States receive a nuclear medicine procedure. Many of the isotopes needed for these procedures are under-produced. Suppliers of the isotopes are usually located outside the United States, which presents a problem when the desired isotopes have short half-lives. Linear accelerators were investigated as a possible method of meeting isotope demand. Linear accelerators are cheaper, safer, and have lower decommissioning costs compared to nuclear reactors. By using (γ,p) reactions, the desired isotope can be separated from the target material due to the different chemical nature of each isotope. Isotopes investigated were Cu-67, In-111, and Lu-111. Using the results the photon flux Monte Carlo simulations, the expected activity of isotopes can be calculated. After samples were irradiated, a high purity germanium detector and signal processing apparatus were used to count the samples. The activity at the time of irradiation stop was then calculated. The uses of medical isotopes will also be presented. Thanks to Idaho State University, the Idaho Accelerator Center, and the National Science Foundation for supporting the research.

  17. Isotope shifts and coulomb displacement energies in calcium isotopes

    NASA Astrophysics Data System (ADS)

    Caurier, E.; Poves, A.; Zuker, A.

    1980-10-01

    Isotope shifts, neutron-proton radii differences and Coulomb displacement energies are calculated for calcium isotopes A = 41 to 48. A simple parametrization of the core polarization terms of the effective force in the framework of the Isospin Projected Hartree-Fock (IPHF) method leads to good agreement between theory and experiment.

  18. Tellurium Stable Isotope Fractionation in Chondritic Meteorites

    NASA Astrophysics Data System (ADS)

    Fehr, M. A.; Hammond, S. J.; Parkinson, I. J.

    2014-09-01

    New Te double spike procedures were set up to obtain high-precision accurate Te stable isotope data. Tellurium stable isotope data for 16 chondrite falls are presented, providing evidence for significant Te stable isotope fractionation.

  19. ENVIRONMENTAL ISOTOPES FOR RESOLUTION OF HYDROLOGY PROBLEMS

    EPA Science Inventory

    The use of environmental isotopes as tracers in the hydrosphere is increasing as analytical instrumentation improves and more applications are discovered. There exists still misconceptions on the role of isotopes in resolving hydrology problems. Naturally occurring isotopes in th...

  20. ENVIRONMENTAL ISOTOPES FOR RESOLUTION OF HYDROLOGY PROBLEMS

    EPA Science Inventory

    The use of environmental isotopes as tracers in the hydrosphere is increasing as analytical instrumentation improves and more applications are discovered. There exists still misconceptions on the role of isotopes in resolving hydrology problems. Naturally occurring isotopes in th...

  1. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  2. ISOTOPE FRACTIONATION PROCESS

    DOEpatents

    Clewett, G.H.; Lee, DeW.A.

    1958-05-20

    A new method is described for isotopic enrichment of uranium. It has been found that when an aqueous acidic solution of ionic tetravalent uraniunn is contacted with chelate complexed tetravalent uranium, the U/sup 238/ preferentially concentrates in the complexed phase while U/sup 235/ concentrates in the ionic phase. The effect is enhanced when the chelate compound is water insoluble and is dissolved in a water-immiscible organic solvent. Cupferron is one of a number of sultable complexing agents, and chloroform is a suitable organic solvent.

  3. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  4. Mass-independent isotope effects.

    PubMed

    Buchachenko, Anatoly L

    2013-02-28

    Three fundamental properties of atomic nuclei-mass, spin (and related magnetic moment), and volume-are the source of isotope effects. The mostly deserved and popular, with almost hundred-year history, is the mass-dependent isotope effect. The first mass-independent isotope effect which chemically discriminates isotopes by their nuclear spins and nuclear magnetic moments rather than by their masses was detected in 1976. It was named as the magnetic isotope effect because it is controlled by magnetic interaction, i.e., electron-nuclear hyperfine coupling in the paramagnetic species, the reaction intermediates. The effect follows from the universal physical property of chemical reactions to conserve angular momentum (spin) of electrons and nuclei. It is now detected for oxygen, silicon, sulfur, germanium, tin, mercury, magnesium, calcium, zinc, and uranium in a great variety of chemical and biochemical reactions including those of medical and ecological importance. Another mass-independent isotope effect was detected in 1983 as a deviation of isotopic distribution in reaction products from that which would be expected from the mass-dependent isotope effect. On the physical basis, it is in fact a mass-dependent effect, but it surprisingly results in isotope fractionation which is incompatible with that predicted by traditional mass-dependent effects. It is supposed to be a function of dynamic parameters of reaction and energy relaxation in excited states of products. The third, nuclear volume mass-independent isotope effect is detected in the high-resolution atomic and molecular spectra and in the extraction processes, but there are no unambiguous indications of its importance as an isotope fractionation factor in chemical reactions.

  5. (Availability of isotopic materials)

    SciTech Connect

    Adair, H.L.

    1987-10-22

    The traveler visited several installations in Belgium, Germany, and England to meet with users of the enriched stable and radioactive materials provided by the ORNL Isotope Distribution Program (IDP). The purpose of the visits was to determine their future needs for the materials and services provided by the ORNL program and to update our existing or potential future customers on the materials and services presently available from the program. In Belgium and England, extreme interest was expressed among our customers and competitors about the status of the High Flux Isotope Reactor (HFIR) at ORNL. This related mainly to our ability to supply the radioisotopes Ir-192 and Gd-153. A number of concerns were expressed about our ability to provide various stable and radioactive materials. Particular concern was expressed about our present capability to supply enriched Kr-85. The traveler participated in an International Atomic Energy Agency (IAEA) specialists' meeting where the chief topic of discussion was the influence of target and sample properties on nuclear data measurements. At the end of this meeting, plans were formalized for a joint IAEA/International Nuclear Target Development Society (INTDS) meeting on sample fabrication and characterization to be held in Darmstadt, Federal Republic of Germany, in 1988. as President, the traveler conducted the 1987 INTDS Board meeting at the Central Bureau of Nuclear Measurements (CBNM). The major agenda items included the recent changes in the INTDS bylaws, guidelines for future hosts of INTDS meetings, and future directions the Society should take.

  6. Si Isotopes of Brownleeite

    NASA Technical Reports Server (NTRS)

    Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

    2010-01-01

    Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

  7. FRAM's Isotopic Uncertainty Analysis.

    SciTech Connect

    Vo, Duc T.

    2005-01-01

    The Fixed-Energy Response-Function Analysis with Multiple Efficiency (FRAM) code was developed at Los Alamos National Laboratory to measure the gamma-ray spectrometry of the isotopic composition of plutonium, uranium, and other actinides. They have studied and identified two different kinds of errors from FRAM analysis: random and systematic. The random errors come mainly from statistics and are easily determined. The systematic errors can come from a variety of sources and can be very difficult to determine. The authors carefully examined the FRAM analytical results of the archival plutonium data and of the data specifically acquired for this isotopic uncertainty analysis project, and found the relationship between the systematic errors and other parameters. They determined that the FRAM's systematic errors could be expressed as functions of the peak resolution and shape, region of analysis, and burnup (for plutonium) or enrichment (for uranium). All other parameters such as weight, matrix material, shape, size, container, electronics, detector, input rate, etc., contribute little to the systematic error or they contribute to the peak resolution and shape and then their contributions can be determined from the peak resolution and shape.

  8. Method of separating boron isotopes

    DOEpatents

    Jensen, R.J.; Thorne, J.M.; Cluff, C.L.

    1981-01-23

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)-dichloroborane as the feed material. The photolysis can readily by achieved with CO/sub 2/ laser radiation and using fluences significantly below those required to dissociate BCl/sub 3/.

  9. Method of separating boron isotopes

    DOEpatents

    Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

    1984-01-01

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

  10. Method of separating boron isotopes

    SciTech Connect

    Jensen, R.J.; Cluff, C.L.; Hayes, J.K.; Thorne, J.M.

    1984-05-08

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO/sub 2/ laser radiation and using fluences significantly below those required to dissociate BCl/sub 3/.

  11. Exotic Structure of Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Sagawa, Hiroyuki; Hagino, Kouichi

    2003-12-01

    Ground state properties of C isotopes, deformation and elecromagnetic moments, as well as electric dipole transition strength are investigated. We first study the ground state properties of C isotopes using a deformed Hartree-Fock (HF) + BCS model with Skyrme interactions. Isotope dependence of the deformation properties is investigated. Shallow deformation minima are found in several neutron-rich C isotopes. It is also shown that the deformation minima appear in both the oblate and the prolate sides in 17C and 19C having almost the same binding energies. Next, we carry out shell model calculations to study electromagnetic moments and electric dipole transitions of C isotopes. We point out the clear configuration dependence of the quadrupole and magnetic moments in the odd C isotopes, which will be useful to find out the deformation and spin-parities of the ground states of these nuclei. Electric dipole states of C isotopes are studied focusing on the interplay between low energy Pigmy strength and giant dipole resonances. Low peak energies, two-peak structure and large widths of the giant resonances show deformation effects. Calculated transition strength below dipole giant resonance in heavier C isotopes than 15C is found to exhaust 12 ~ 15% of the Thomas-Reiche-Kuhn sum rule value and 50 ~ 80% of the cluster sum rule value.

  12. Aleutian terranes from Nd isotopes

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Kay, S. M.; Rubenstone, J. L.

    1986-01-01

    Nd isotope ratios substantiate the identification of oceanic crustal terranes within the continental crustal basement of the Aleutian island arc. The oceanic terranes are exposed in the westernmost Aleutians, but to the east, they are completely buried by isotopically distinct arc-volcanic rocks. Analogous oceanic terranes may be important components of the terrane collages that comprise the continents.

  13. Calcium isotopes in wine

    NASA Astrophysics Data System (ADS)

    Holmden, C. E.

    2011-12-01

    The δ 44/40Ca values of bottled wine vary between -0.76% to -1.55% on the seawater scale and correlate weakly with inverse Ca concentration and Mg/Ca ratio, such that the lowest δ 44/40Ca values have the highest Ca concentrations and lowest Mg/Ca ratios. The correlation is notable in the sense that the measured wines include both whites and reds sampled from different wine growing regions of the world, and cover a wide range of quality. Trends among the data yield clues regarding the cause of the observed isotopic fractionation. White wines, and wines generally perceived to be of lower quality, have lower δ 44/40Ca values compared to red wines and wines of generally perceived higher quality. Quality was assessed qualitatively through sensory evaluation, price, and scores assigned by critics. The relationship between δ 44/40Ca and wine quality was most apparent when comparing wines of one varietal from one producer from the same growing region. In the vineyard, wine quality is related to factors such as the tonnage of the crop and the ripeness of the grapes at the time of harvesting, the thickness of the skins for reds, the age of the vines, as well as the place where the grapes were grown (terroir). Quality is also influenced by winemaking practices such as fermentation temperature, duration of skin contact, and barrel ageing. Accordingly, the relationship between δ 44/40Ca and wine quality may originate during grape ripening in the vineyard or during winemaking in the cellar. We tested the grape ripening hypothesis using Merlot grapes sampled from a vineyard in the Okanagan, British Columbia, using sugar content (degrees Brix) as an indicator of ripeness. The grapes were separated into pulp, skin, and pip fractions and were analyzed separately. Thus far, there is no clear evidence for a systematic change in δ 44/40Ca values associated with progressive ripening of grapes in the vineyard. On the day of harvesting, the δ 44/40Ca value of juice squeezed from

  14. Molybdenum Isotopes and Soil Processes

    NASA Astrophysics Data System (ADS)

    Siebert, C.; Pett-Ridge, J. C.; Halliday, A. N.; Burton, K. W.

    2011-12-01

    The oxygenation state of Earth's oceans is a driver of evolution and extinction events as well as climate change. In recent years stable isotope fractionation of redox sensitive elements such as molybdenum (Mo) have been used as quantitative tracers of past redox-conditions in a number of marine environments. However, little is known about the processes controlling the Mo isotope compositions of the riverine inputs to the oceans and their short- and long-term variations. Several recent studies [Archer & Vance, 2008; Pearce et al., 2010] have shown that many river waters have heavy Mo isotope compositions. In some terrestrial weathering environments dissolved Mo isotope compositions in rivers are controlled by the catchment lithology [Neubert et al., 2011]. However, many rivers show fractionation of Mo isotopes relative to their catchment lithology. Possible mechanisms causing this fractionation are chemical weathering and pedogenic processes. This study has investigated the behavior of Mo isotopes during weathering of basalt under different conditions. Results from oxic to reducing soil profiles in Hawaii show that redox conditions during soil formation can control Mo isotope compositions in soils. Reducing soil profiles have light isotope compositions whereas oxidizing profiles are heavy. This general isotope behavior is confirmed by results from soil profiles from Iceland. Here reducing layers within the profiles show marked negative isotope excursions. In oxic profiles a surprisingly strong interaction of Mo with organic matter can be observed producing significant Mo isotope fractionation. This behavior might explain long term retention of Mo in soils besides its high mobility in molybdate form. Mo associated with organic matter is bioavailable and essential for processes like nitrogen fixation. In addition, we observe that fractionation relative to the source rock is dependent on the degree of weathering, i.e. relatively un-weathered profiles do not show

  15. Correlated optical and isotopic nanoscopy

    PubMed Central

    Saka, Sinem K.; Vogts, Angela; Kröhnert, Katharina; Hillion, François; Rizzoli, Silvio O; Wessels, Johannes T.

    2014-01-01

    The isotopic composition of different materials can be imaged by secondary ion mass spectrometry. In biology, this method is mainly used to study cellular metabolism and turnover, by pulsing the cells with marker molecules such as amino acids labelled with stable isotopes (15N, 13C). The incorporation of the markers is then imaged with a lateral resolution that can surpass 100 nm. However, secondary ion mass spectrometry cannot identify specific subcellular structures like organelles, and needs to be correlated with a second technique, such as fluorescence imaging. Here, we present a method based on stimulated emission depletion microscopy that provides correlated optical and isotopic nanoscopy (COIN) images. We use this approach to study the protein turnover in different organelles from cultured hippocampal neurons. Correlated optical and isotopic nanoscopy can be applied to a variety of biological samples, and should therefore enable the investigation of the isotopic composition of many organelles and subcellular structures. PMID:24718107

  16. Ca isotope variations in Allende

    NASA Technical Reports Server (NTRS)

    Jungck, M. H. A.; Shimamura, T.; Lugmair, G. W.

    1984-01-01

    Ca-isotope measurements of Allende Ca-Al-rich inclusions (CAIs), together with those on an apatite-enriched fraction from Orgueil, indicate the existence of widespread excesses on the neutron-rich isotope Ca-48. Isotopic anomalies are noted in 7 out of 11 CAIs analyzed. This abundance of isotopic excesses places Ca alongside Ti and O, although no clear correlation has yet been found between Ca-48 and Ti-50, which are thought to be coproduced by neutron-rich nucleosynthetic processes within stars. It is suggested that the higher volatility of Ca, by comparison with Ti compounds, led to a variable dilution with isotopically normal Ca in vaporization and recondensation processes in stellar envelopes, the interstellar medium, and/or the solar nebula.

  17. Isotope separation by laser means

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1982-06-15

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  18. Americium behaviour in plastic vessels.

    PubMed

    Legarda, F; Herranz, M; Idoeta, R; Abelairas, A

    2010-01-01

    The adsorption of (241)Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of (241)Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of (241)Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification. Copyright 2009 Elsevier Ltd. All rights reserved.

  19. Phonon properties of americium phosphide

    SciTech Connect

    Arya, B. S.; Aynyas, Mahendra; Sanyal, S. P.

    2016-05-23

    Phonon properties of AmP have been studied by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, specific heat calculated from present model. The calculated phonon dispersion curves of AmP are presented follow the same trend as observed in uranium phosphide. We discuss the significance of this approach in predicting the phonon dispersion curves of these compounds and examine the role of electron-phonon interaction.

  20. Phonon properties of americium phosphide

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Sanyal, S. P.

    2016-05-01

    Phonon properties of AmP have been studied by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, specific heat calculated from present model. The calculated phonon dispersion curves of AmP are presented follow the same trend as observed in uranium phosphide. We discuss the significance of this approach in predicting the phonon dispersion curves of these compounds and examine the role of electron-phonon interaction.

  1. The unveiled states of americium

    NASA Astrophysics Data System (ADS)

    Still, Ben

    2017-02-01

    Made under a cloak of wartime secrecy, yet announced in the most public of ways -- a radioactive element that governments insist we take into our homes. Ben Still explains how element 95 is one of real contradiction.

  2. Cometary Isotopic Measurements

    NASA Astrophysics Data System (ADS)

    Bockelée-Morvan, Dominique; Calmonte, Ursina; Charnley, Steven; Duprat, Jean; Engrand, Cécile; Gicquel, Adeline; Hässig, Myrtha; Jehin, Emmanuël; Kawakita, Hideyo; Marty, Bernard; Milam, Stefanie; Morse, Andrew; Rousselot, Philippe; Sheridan, Simon; Wirström, Eva

    2015-12-01

    Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. We review here measurements acquired on the D/H, 14N/15N, 16O/18O, 12C/13C, and 32S/34S ratios in cometary grains and gases, and discuss their cosmogonic implications. The review includes analyses of potential cometary material available in collections on Earth, recent measurements achieved with the Herschel Space Observatory, large optical telescopes, and Rosetta, as well as recent results obtained from models of chemical-dynamical deuterium fractionation in the early solar nebula. Prospects for future measurements are presented.

  3. Carbon isotopes in comets

    NASA Technical Reports Server (NTRS)

    Wehinger, Peter A.

    1990-01-01

    The progress is reported of high resolution spectra of selected bright comets with the aim of determining the carbon isotope abundance ratio, C-12/C-13. The ratio was determined for various Solar System objects (in the atmospheres of the giant planets, meteorites, the Earth, and the solar photosphere), where the C-12/C-13 = 89/1. In the interstellar medium, optical and radio observations give a range of C-12/C-13 = 43-67/1 depending on the observing techniques used and the specific interstellar cloud observed. The echelle spectra is presented of the CN(0,0) violet system in three comets: P/Brorsen-Metcalf, C/Okazaki-Levy-Rudenko, and C/Austin. P/Brorsen-Metcalf has a period of 70 y (prograde) compared with P/Halley which is 76 y (retrograde). The similar periods made P/Brorsen-Metcalf of special interest for comparison with P/Halley.

  4. Container for hydrogen isotopes

    DOEpatents

    Solomon, David E.

    1977-01-01

    A container for the storage, shipping and dispensing of hydrogen isotopes such as hydrogen, deuterium, tritium, or mixtures of the same which has compactness, which is safe against fracture or accident, and which is reusable. The container consists of an outer housing with suitable inlet and outlet openings and electrical feed elements, the housing containing an activated sorber material in the form, for example, of titanium sponge or an activated zirconium aluminate cartridge. The gas to be stored is introduced into the chamber under conditions of heat and vacuum and will be retained in the sorber material. Subsequently, it may be released by heating the unit to drive off the stored gas at desired rates.

  5. New, heavy transuranium isotopes

    SciTech Connect

    Hulet, E.K.

    1990-10-22

    In this report, we offer our most recent results concerning the decay properties for five new isotopes of Md, No, Lr, and for {sup 258m}Md. In additions to these successful experiments, we have also conducted searches for {sup 263}(105), {sup 264}(105), {sup 272}(109), and superheavy elements from bombardments of {sup 254}Es with heavy ions. {sup 2} An exciting finding in the course of this work is a new fission phenomenon, which we have termed bidmodal fission''. This is described in a subsequent section. The final part summarizes our conclusions based on the unexpectedly long half-lives and surprising fission properties of the heaviest nuclei. 27 refs., 19 figs.

  6. Isotopic analysis of planetary solids

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Neuland, M.; Meyer, S.; Wurz, P.

    2013-09-01

    Isotopic analysis of planetary surfaces is of considerable interest for planetology. Studies of isotope composition can deliver information on radio-isotope chronology of planetary soil/regolith, an insight to processes that altered planetary surface (space weathering) or on possible biogenic processes that occurred or still occur on the planet. Mass spectrometry is a well-suited method that delivers accurate and precise isotope composition. Among other instruments (LAZMA and LAMS), the miniature laser ablation/ionisation mass analyser, LMS developed in Bern for in situ space research can be used to measure the elemental and isotopic composition of planetary solids. LMS support mass spectrometric investigation with a mass resolution of m/Δm≈500-1500, dynamic range of at least 8 decades and detection sensitivity of ~10 ppb. Current studies of various solid materials and standard reference materials show that isotope composition can be conducted with an accuracy and precision at per mill level if the isotope concentration exceeds 10-100 ppm. Implications of the studies for in situ application are discussed.

  7. Isotope effects in ESR spectroscopy.

    PubMed

    Stößer, Reinhard; Herrmann, Werner

    2013-06-07

    In order to present the relationship between ESR spectroscopy and isotope effects three levels are considered: (i) ESR spectroscopy is described on a general level up to the models for interpretation of the experimental spectra, which go beyond the usually used time and mass independent spin-Hamilton operator, (ii) the main characteristics of the generalized isotope effects are worked out, and finally (iii) the basic, mainly quantum mechanical effects are used to describe the coupling of electron spins with the degrees of freedom, which are accessible under the selected conditions, of the respective paramagnetic object under investigation. The ESR parameters and the respective models are formalized so far, that they include the time and mass depending influences and reflect the specific isotope effects. Relations will be established between the effects in ESR spectra to spin relaxation, to spin exchange, to the magnetic isotope effect, to the Jahn-Teller effects, as well as to the influence of zero-point vibrations. Examples will be presented which demonstrate the influence of isotopes as well as the kind of accessible information. It will be differentiated with respect to isotope effects in paramagnetic centres itself and in the respective matrices up to the technique of ESR imaging. It is shown that the use of isotope effects is indispensable in ESR spectroscopy.

  8. Microbes: Agents of Isotopic Change

    NASA Astrophysics Data System (ADS)

    Fogel, M. L.

    2012-12-01

    Microbes drive many of the important oxidation and reduction reactions on Earth; digest almost all forms of organic matter; and can serve as both primary and secondary producers. Because of their versatile biochemistry and physiology, they impart unique isotopic signatures to organic and inorganic materials, which have proven to be key measurements for understanding elemental cycling now and throughout Earth's history. Understanding microbial isotope fractionations in laboratory experiments has been important for interpreting isotopic patterns measured in natural settings. In fact, the pairing of simple experiment with natural observation has been the pathway for interpreting the fingerprint of microbial processes in ancient sediments and rocks. Examples of how key experiments have explained stable isotope fractionations by microbes and advanced the field of microbial ecology will be presented. Learning the isotopic signatures of Earth's microbes is a valuable exercise for predicting what isotopic signatures could be displayed by possible extant or extinct extraterrestrial life. Given the potential for discovery on Mars, Enceladus, and other solar system bodies, new methods and techniques for pinpointing what is unique about microbial isotope signatures is particularly relevant.

  9. Calcium isotopic compositions of chondrites

    NASA Astrophysics Data System (ADS)

    Huang, Shichun; Jacobsen, Stein B.

    2017-03-01

    We report mass-dependent and mass-independent Ca isotopic variations in nine chondrites from three groups: carbonaceous, ordinary and enstatite chondrites. There is about 0.25‰ per amu, i.e., ∼1‰ in 44Ca/40Ca, variation in chondrites: carbonaceous chondrites have the lightest Ca isotopes, enstatite chondrites have modeled bulk Earth like Ca isotopes, and ordinary chondrites are in between. The correlations between mass-dependent Ca isotopic variation and chemical variations in chondrites may reflect variable contributions from different endmembers, including refractory inclusions, in different chondrite groups. In detail, enstatite chondrites and the Earth share similar isotopic characteristics, but are very different in chemical compositions. At the ±1 and ±2 ε-unit levels, respectively, there is no measurable 40Ca or 43Ca anomaly in bulk chondrites. Carbonaceous chondrites show several ε-units of 48Ca excess. That is, Ca exhibits both mass-dependent and mass-independent isotopic variations in chondrites, similar to O isotopes. The 48Ca anomaly in bulk chondrites is positively correlated with 50Ti anomaly, but does not form simple correlation with 54Cr anomaly, implying multiple supernova sources for these neutron-rich isotopes in the Solar System. Finally, all meteorites with negative Δ17O have either 48Ca deficits (differentiated meteorites) or 48Ca excess (carbonaceous chondrites), implying that the Sun with a very negative Δ17O is probably also characterized by 48Ca anomaly compared to the Earth. CAIs cannot be taken as representative of the initial isotopic compositions of refractory elements like Ca for the Earth-Moon system.

  10. Carbon isotope geochemistry and geobiology

    NASA Technical Reports Server (NTRS)

    Desmarais, D.

    1985-01-01

    Carbon isotope fractionation values were used to understand the history of the biosphere. For example, plankton analyses confirmed that marine extinctions at the end of the Cretaceous period were indeed severe (see Hsu's article in Sundquist and Broeker, 1984). Variations in the isotopic compositions of carbonates and evaporitic sulfates during the Paleozoic reflect the relative abundances of euxinic (anoxic) marine environments and organic deposits from terrestrial flora. The carbon isotopic composition of Precambrian sediments suggest that the enzyme ribulose bisphosphate carboxylase has existed for perhaps 3.5 billion years.

  11. Neodymium isotopic variations in seawater

    NASA Technical Reports Server (NTRS)

    Piepgras, D. J.; Wasserburg, G. J.

    1980-01-01

    Direct measurement of the isotopic composition of Nd in the Atlantic agree with the Nd content in ferromanganese sediments and differ from the observed amounts in the Pacific samples. These data indicate the existence of distinctive differences in the isotopic composition of Nd in the waters of major oceans; the average values determined from seawater and ferromanganese sediments are considerably lower than in sources with oceanic mantle affinities showing that the REE in the oceans is dominated by continental sources. The Nd isotopic variations in seawater are applied to relate the residence time of Nd and mixing rates between the oceans.

  12. Stable isotopes in obesity research.

    PubMed

    Dolnikowski, Gregory G; Marsh, Julian B; Das, Sai Krupa; Welty, Francine K

    2005-01-01

    Obesity is recognized as a major public health problem. Obesity is a multifactorial disease and is often associated with a wide range of comorbidities including hypertension, non-insulin dependent (Type II) diabetes mellitus, and cardiovascular disease, all of which contribute to morbidity and mortality. This review deals with stable isotope mass spectrometric methods and the application of stable isotopes to metabolic studies of obesity. Body composition and total energy expenditure (TEE) can be measured by mass spectrometry using stable isotope labeled water, and the metabolism of protein, lipid, and carbohydrate can be measured using appropriate labeled tracer molecules.

  13. Compelling Research Opportunities using Isotopes

    SciTech Connect

    2009-04-23

    Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1) medicine

  14. Apparatus and process for separating hydrogen isotopes

    DOEpatents

    Heung, Leung K; Sessions, Henry T; Xiao, Xin

    2013-06-25

    The apparatus and process for separating hydrogen isotopes is provided using dual columns, each column having an opposite hydrogen isotopic effect such that when a hydrogen isotope mixture feedstock is cycled between the two respective columns, two different hydrogen isotopes are separated from the feedstock.

  15. Method for laser induced isotope enrichment

    DOEpatents

    Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

    2004-09-07

    Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

  16. Isotope separation using metallic vapor lasers

    NASA Technical Reports Server (NTRS)

    Russell, G. R.; Chen, C. J.; Harstad, K. G. (Inventor)

    1977-01-01

    The isotope U235 is separated from a gasified isotope mixture of U235 and U238 by selectively exciting the former from the ground state utilizing resonant absorption of radiation from precisely tuned lasers. The excited isotope is then selectively ionized by electron bombardment. It then is separated from the remaining isotope mixture by electromagnetic separation.

  17. Raman scattering method and apparatus for measuring isotope ratios and isotopic abundances

    DOEpatents

    Harney, Robert C.; Bloom, Stewart D.

    1978-01-01

    Raman scattering is used to measure isotope ratios and/or isotopic abundances. A beam of quasi-monochromatic photons is directed onto the sample to be analyzed, and the resulting Raman-scattered photons are detected and counted for each isotopic species of interest. These photon counts are treated mathematically to yield the desired isotope ratios or isotopic abundances.

  18. Lasers utilizing CO2 isotopes

    NASA Astrophysics Data System (ADS)

    Pechenin, Yu V.; Domanov, M. S.

    1980-08-01

    The lasing spectra and energy characteristics were investigated for lasers operating with the isotopes 12C16O2, 13C16O2, 12C18O2, and 12C16O18O. It was found that the output power of a laser utilizing the CO2 isotopes was determined by the content of a particular isotope in the carbon dioxide gas. For equal enrichments, all the isotopes investigated, with the exception of 12C16O18O, gave comparable output powers. The unsaturated gains were identical for the most intense transitions of the symmetric molecules; the gain was a factor of two less for the asymmetric molecule. The gain rose linearly with increasing enrichment. The ultimate specific power output, given by the product of the saturation power density and the gain, was practically independent of the enrichment.

  19. Isotopic Changes During Digestion: Protein

    NASA Astrophysics Data System (ADS)

    Tuross, N.

    2013-12-01

    Nutrient and hydrological inputs traverse a complicated route of pH, enzymatic and cellular processes in digestion in higher animals. The end products of digestion are the starting products for biosynthesis that are often used to interpret past life-ways. Using an artificial gut system, the isotopic changes (dD, d18O, d13C and d15N) of protein are documented. Three separate protein sources are subjected to the conditions, chemical and enzymatic, found in the stomach and upper small intestine with only a small shift in the oxygen isotopic composition of the proteins observed. Middle to lower small intestine parameters produced both greater isotopic effects and significantly lower molecular weight products. The role of the gastric enterocyte and the likely involvement of the internal milieu of this cell in the isotopic composition of amino acids that are transported to the liver are reported.

  20. Isotopic Analysis and Evolved Gases

    NASA Technical Reports Server (NTRS)

    Swindle, Timothy D.; Boynton, William V.; Chutjian, Ara; Hoffman, John H.; Jordan, Jim L.; Kargel, Jeffrey S.; McEntire, Richard W.; Nyquist, Larry

    1996-01-01

    Precise measurements of the chemical, elemental, and isotopic composition of planetary surface material and gases, and observed variations in these compositions, can contribute significantly to our knowledge of the source(s), ages, and evolution of solar system materials. The analyses discussed in this paper are mostly made by mass spectrometers or some other type of mass analyzer, and address three broad areas of interest: (1) atmospheric composition - isotopic, elemental, and molecular, (2) gases evolved from solids, and (3) solids. Current isotopic data on nine elements, mostly from in situ analysis, but also from meteorites and telescopic observations are summarized. Potential instruments for isotopic analysis of lunar, Martian, Venusian, Mercury, and Pluto surfaces, along with asteroid, cometary and icy satellites, surfaces are discussed.

  1. Isotopes on the TSCA Inventory

    EPA Pesticide Factsheets

    This document is to help the regulated community comply with the requirements of the Toxic Substances Control Act (TSCA) Section 5 Premanufacturing Notice (PMN) Program for chemical substances that contain deliberate isotopic modifications.

  2. Physics with isotopically controlled semiconductors

    SciTech Connect

    Haller, E. E.

    2010-07-15

    This paper is based on a tutorial presentation at the International Conference on Defects in Semiconductors (ICDS-25) held in Saint Petersburg, Russia in July 2009. The tutorial focused on a review of recent research involving isotopically controlled semiconductors. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, is the most prominent effect for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples.

  3. Stable isotope research pool inventory

    SciTech Connect

    Not Available

    1985-02-01

    This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for non-destructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, /sup 40/Ca and /sup 56/Fe. All request for the loan of samples should be submitted with a summary of the purpose of the loan to: Isotope Distribution Office, Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, Tennessee 37831. Requests from non-DOE contractors and from foreign institutions require DOE approval.

  4. Selective photoionisation of lutetium isotopes

    SciTech Connect

    D'yachkov, Aleksei B; Kovalevich, S K; Labozin, Valerii P; Mironov, Sergei M; Panchenko, Vladislav Ya; Firsov, Valerii A; Tsvetkov, G O; Shatalova, G G

    2012-10-31

    A three-stage laser photoionisation scheme intended for enriching the {sup 176}Lu isotope from natural lutetium was considered. An investigation was made of the hyperfine structure of the second excited state 5d6s7s {yields} {sup 4}D{sub 3/2} with an energy of 37194 cm{sup -1} and the autoionisation state with an energy of 53375 cm{sup -1} of the {sup 176}Lu and {sup 175}Lu isotopes. The total electron momentum of the autoionisation level and the constant A of hyperfine magnetic interaction were determined. Due to a small value of the isotopic shift between {sup 176}Lu and {sup 175}Lu, appreciable selectivity of their separation may be achieved with individual hyperfine structure components. The first tentative enrichment of the 176Lu isotope was performed to a concentration of 60 % - 70 %. (laser applications and other topics in quantum electronics)

  5. Novel hybrid isotope separation scheme and apparatus

    DOEpatents

    Maya, Jakob

    1991-01-01

    A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which the specific isotope is to be isolated, radiating the gas with frequencies characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photoionization reaction of the desired isotope, and collecting the specific isotope ion by suitable ion collection means.

  6. Novel hybrid isotope separation scheme and apparatus

    DOEpatents

    Maya, J.

    1991-06-18

    A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which the specific isotope is to be isolated, radiating the gas with frequencies characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photoionization reaction of the desired isotope, and collecting the specific isotope ion by suitable ion collection means. 3 figures.

  7. Isotope dilution mass spectrometry

    NASA Astrophysics Data System (ADS)

    Heumann, Klaus G.

    1992-09-01

    In the past isotope dilution mass spectrometry (IDMS) has usually been applied using the formation of positive thermal ions of metals. Especially in calibrating other analytical methods and for the certification of standard reference materials this type of IDMS became a routine method. Today, the progress in this field lies in the determination of ultra trace amounts of elements, e.g. of heavy metals in Antarctic ice and in aerosols in remote areas down to the sub-pg g-1 and sub-pg m-3 levels respectively, in the analysis of uranium and thorium at concentrations of a few pg g-1 in sputter targets for the production of micro- electronic devices or in the determination of sub-picogram amounts of230Th in corals for geochemical age determinations and of226Ra in rock samples. During the last few years negative thermal ionization IDMS has become a frequently used method. The determination of very small amounts of selenium and technetium as well as of other transition metals such as vanadium, chromium, molybdenum and tungsten are important examples in this field. Also the measurement of silicon in connection with a re-determination of Avogadro's number and osmium analyses for geological age determinations by the Re/Os method are of special interest. Inductively-coupled plasma mass spectrometry is increasingly being used for multi-element analyses by the isotope dilution technique. Determinations of heavy metals in samples of marine origin are representative examples for this type of multi-element analysis by IDMS. Gas chromatography-mass spectrometry systems have also been successfully applied after chelation of metals (for example Pt determination in clinical samples) or for the determination of volatile element species in the environment, e.g. dimethyl sulfide. However, IDMS--specially at low concentration levels in the environment--seems likely to be one of the most powerful analytical methods for speciation in the future. This has been shown, up to now, for species of

  8. Clumped isotope thermometry and catagenesis

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.; Clog, M. D.; Dallas, B.; Douglas, P. M.; Piasecki, A.; Sessions, A. L.; Stolper, D. A.

    2014-12-01

    Clumped- and site-specific isotopic compositions of organic compounds can constrain their formation temperatures, sources, and chemical reaction histories. The large number of isotopologues of organic molecules may allow for the isotopic composition of a single compound to illuminate many processes. For example, it is possible that clumping or site specific effects in different parts of the same molecule will differ in blocking temperature, such that a molecule's full isotopic structure could simultaneously constrain conditions of biosynthesis, catagenic 'cracking', and storage in the crust. Recent innovations in high-resolution mass spectrometry and methods of IR and NMR spectroscopy make it possible to explore these questions. Methane is the first organic molecule to have its clumped isotope geochemistry analyzed in a variety of natural environments and controlled experiments. Methane generated through catagenic cracking of kerogen and other organic matter forms in equilibrium with respect to isotopic clumping, and preserves that state through later storage or migration, up to temperatures of ~250 ˚C. This kinetic behavior permits a variety of useful geological applications. But it is unexpected because the bulk stable isotope composition of thermogenic methane is thought to reflect kinetic isotope effects on irreversible reactions. Our observations imply a new interpretation of the chemical physics of catagenic methane formation. Additional instrument and methods developments are currently extending the measurement of isotopic clumping and position specific effects to larger alkanes, other hydrocarbon compounds, and amino acids. These measurements will ultimately expand our capacity to understand the formational conditions and fates of organic molecules in high- and low-temperature environments through geological time.

  9. Isotope-Identifying neutron reflectometry

    SciTech Connect

    Nikitenko, Yu. V. Petrenko, A. V.; Gundorin, N. A.; Gledenov, Yu. M.; Aksenov, V. L.

    2015-07-15

    The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a noncollinear magnetic field and on nuclei of elements with spin, makes it possible to implement isotope-indentifying neutron reflectometry.

  10. Isotope separation apparatus and method

    DOEpatents

    Feldman, Barry J.

    1985-01-01

    The invention relates to an improved method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferably substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. Because the molecules in the beam occupy various degenerate energy levels, if the laser beam comprises chirped pulses comprising selected wavelengths, the laser beam will very efficiently excite substantially all unexcited molecules and will cause stimulated emission of substantially all excited molecules of a selected one of the isotopes in the beam which such pulses encounter. Excitation caused by first direction chirped pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning chirped pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement of essentially all the molecules containing the one isotope is accomplished by a large number of chirped pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam.

  11. Selected scientific topics of the 11th International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labeled Compounds.

    PubMed

    Atzrodt, Jens; Derdau, Volker

    2013-01-01

    This micro-review describes hot topics and new trends in isotope science discussed at the 11th International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labeled Compounds from a personal perspective.

  12. Electron linac for medical isotope production with improved energy efficiency and isotope recovery

    DOEpatents

    Noonan, John; Walters, Dean; Virgo, Matt; Lewellen, John

    2015-09-08

    A method and isotope linac system are provided for producing radio-isotopes and for recovering isotopes. The isotope linac is an energy recovery linac (ERL) with an electron beam being transmitted through an isotope-producing target. The electron beam energy is recollected and re-injected into an accelerating structure. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-x-ray converter.

  13. Isotopic fractionation by diffusion in groundwater

    NASA Astrophysics Data System (ADS)

    Labolle, Eric M.; Fogg, Graham E.; Eweis, Juana B.; Gravner, Janko; Leaist, Derek G.

    2008-07-01

    During the last decade, isotopic fractionation has gained acceptance as an indicator of microbiological and chemical transformations of contaminants in groundwater. These transformation processes typically favor isotopically light, compared to isotopically heavy, contaminants, resulting in enrichment of the latter in the residual aqueous phase. In these isotope applications, it has been generally presumed that physical transport processes in groundwater have a negligible effect on isotopic enrichment. It is well known, however, that aqueous phase diffusion generally proceeds faster for isotopically light, compared to isotopically heavy, solute molecules, often resulting in isotopic fractionation in groundwater. This paper considers the potential for isotopic fractionation during transport in groundwater resulting from minute isotopic effects on aqueous diffusion coefficients. Analyses of transport in heterogeneous systems delimit the viable range of isotopic fractionation by diffusion in groundwater. Results show that diffusion can result in similar degrees of depletion and enrichment of isotopically heavy solutes during transport in heterogeneous systems with significant diffusion rate-limited mass transfer between fast- and slow-flow zones. Additional analyses and examples explore conditions that attenuate the development of significant fractionation. Examples are presented for 13C methyl tertiary butyl ether and deuterated and nondeuterated isopropanol and tertiary butyl alcohol using aqueous diffusion coefficients measured by the Taylor dispersion method with refractive index profiling as a part of this study. Examples elucidate the potential for diffusive fractionation as a confounder in isotope applications and emphasize the importance of hydrogeologic analysis for assessing the role of diffusive fractionation in isotope applications at contaminant field sites.

  14. Calcium Isotope Analysis by Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Boulyga, S.; Richter, S.

    2010-12-01

    The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. This presentation discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. Additionally, the availability of Ca isotope reference materials will be discussed.

  15. Photodisintegration of Lithium Isotopes

    NASA Astrophysics Data System (ADS)

    Wurtz, Ward Andrew

    We have performed a measurement of the photodisintegration of the lithium isotopes, 6Li and 7Li, using a monochromatic, polarised photon beam and a segmented neutron detector array which covers approximately ¼ of 4pi srad. Using time-of-flight and scintillator light-output spectra we separate the data into individual reaction channels. This work is motivated by the need to compare with recent theoretical predictions and to provide data for future theoretical work. For the photodisintegration of 6Li we took data at 12 photon energies between 8 and 35 MeV. We describe the data using a model consisting of two-body reaction channels and obtain angular distributions and absolute cross sections for many of these reaction channels. We compare our results with a recent Lorentz integral transform calculation (Bacca et al. Phys. Rev. C 69, 057001 (2004)). Our results are in reasonable agreement with the calculation, in contradiction with previous experimental results. For the photodisintegration of 7Li, we took data at 9 photon energies between 10 and 35 MeV. We obtain cross sections for the reaction channel 7Li + gamma → n + 6 Li(g.s.) at all photon energies with angular distributions at all but the highest energy. We obtain angular distributions and total cross sections for reaction channels involving excited states of the daughter nucleus, 6Li, at select energies. We hope that these measurements will provide incentive for new theoretical calculations. We observe neutrons that can only be described by the reaction channel 7Li + gamma → n + 6Li(10.0) which necessitates an excited state of 6Li with excitation energy Ex = 10.0 +/- 0.5 MeV that is not in the standard tables of excited states. ii

  16. Isotope shifts in francium isotopes Fr-213206 and 221Fr

    NASA Astrophysics Data System (ADS)

    Collister, R.; Gwinner, G.; Tandecki, M.; Behr, J. A.; Pearson, M. R.; Zhang, J.; Orozco, L. A.; Aubin, S.; Gomez, E.; FrPNC Collaboration

    2014-11-01

    We present the isotope shifts of the 7 s1 /2 to 7 p1 /2 transition for francium isotopes 206 -213Fr with reference to 221Fr collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7 s1 /2 to 7 p3 /2 isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D1 and D2 transitions, of sufficient precision to differentiate between ab initio calculations.

  17. Selectivity of bis-triazinyl bipyridine ligands for americium(III) in Am/Eu separation by solvent extraction. Part 1. Quantum mechanical study on the structures of BTBP complexes and on the energy of the separation.

    PubMed

    Narbutt, Jerzy; Oziminski, Wojciech P

    2012-12-21

    Theoretical studies were carried out on two pairs of americium and europium complexes formed by tetra-N-dentate lipophilic BTBP ligands, neutral [ML(NO(3))(3)] and cationic [ML(2)](3+) where M = Am(III) or Eu(III), and L = 6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (C2-BTBP). Molecular structures of the complexes have been optimized at the B3LYP/6-31G(d) level and total energies of the complexes in various media were estimated using single point calculations performed at the B3LYP/6-311G(d,p) and MP2/6-311G(d,p) levels of theory. In the calculations americium and europium ions were treated using pseudo-relativistic Stuttgart-Dresden effective core potentials and the accompanying basis sets. Selectivity in solvent extraction separation of two metal ions is a co-operative function of contributions from all extractable metal complexes, which depend on physico-chemical properties of each individual complex and on its relative amount in the system. Semi-quantitative analysis of BTBP selectivity in the Am/Eu separation process, based on the contributions from the two pairs of Am(III) and Eu(III) complexes, has been carried out. To calculate the energy of Am/Eu separation, a model of the extraction process was used, consisting of complex formation in water and transfer of the formed complex to the organic phase. Under the assumptions discussed in the paper, this simple two-step model results in reliable values of the calculated differences in the energy changes for each pair of the Am/Eu complexes in both steps of the process. The greater thermodynamic stability (in water) of the Am-BTBP complexes, as compared with the analogous Eu species, caused by greater covalency of the Am-N than Eu-N bonds, is most likely the main reason for BTBP selectivity in the separation of the two metal ions. The other potential reason, i.e. differences in lipophilic properties of the analogous complexes of Am and Eu, is less important with regard to this selectivity.

  18. Isotopic Randomness and Maxwell's Demon

    NASA Astrophysics Data System (ADS)

    Berezin, Alexander A.

    2005-03-01

    Isotopic disorder in crystals can lead to suppression of thermal conductivity, mobility variations and (weak) Anderson localization on isotopic fluctuations. The latter (AAB, J.ChemPhys.1984) is akin to polaron effect (self-localization due polarization). Possibility of isotopic patterning (IP) increases near melting point (thermally activated isotopic hopping swaps). Crystal near melting threshold become “informationally sensitive” as if its IP is operated by some external Maxwell’s Demon, MD (AAB, URAM J, 2002). At this state short range (e.g. electrostatic inverse square) forces evolve into long-range interactions (due to divergence of order parameter) and information sensitivity can be further amplified by (say) a single fast electron (e.g. beta-particle from decay of 14-C or other radioactive isotope) which may result in cascade of impact ionization events and (short time-scale) enhancement of screening by impact-generated non-equilibrium (non-thermal) electrons. In this state informationally driven (MD-controlled) IP (Eccles effect) can result in decrease of positional entropy signifying emergence of physical complexity out of pure information, similar to peculiar “jinni effect” on closed time loops in relativistic cosmology (R.J.Gott, 2001) or Wheeler’s “it from bit” metaphor. By selecting special IP, MD modifies ergodicity principle in favor of info rich states.

  19. Isotope separation apparatus and method

    DOEpatents

    Cotter, Theodore P.

    1982-12-28

    The invention relates to a method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferable substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. The laser beam comprises .pi.-pulses of a selected wavelength which excite unexcited molecules, or cause stimulated emission of excited molecules of one of the isotopes. Excitation caused by first direction .pi.-pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning .pi.-pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement is accomplished by a large number of .pi.-pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam.

  20. Stable isotopes in tree rings

    NASA Astrophysics Data System (ADS)

    McCarroll, Danny; Loader, Neil J.

    2004-04-01

    Stable isotopes in tree rings could provide palaeoclimate reconstructions with perfect annual resolution and statistically defined confidence limits. Recent advances make the approach viable for non-specialist laboratories. The relevant literature is, however, spread across several disciplines, with common problems approached in different ways. Here we provide the first overview of isotope dendroclimatology, explaining the underlying theory and describing the steps taken in building and interpreting isotope chronologies. Stable carbon isotopes record the balance between stomatal conductance and photosynthetic rate, dominated at dry sites by relative humidity and soil water status and at moist sites by summer irradiance and temperature. Stable oxygen and hydrogen isotopic ratios record source water, which contains a temperature signal, and leaf transpiration, controlled dominantly by vapour pressure deficit. Variable exchange with xylem (source) water during wood synthesis determines the relative strength of the source water and leaf enrichment signals. Producing long Holocene chronologies will require a change in emphasis towards processing very large numbers of samples efficiently, whilst retaining analytical precision. A variety of sample preparation and data treatment protocols have been used, some of which have a deleterious effect on the palaeoclimate signal. These are reviewed and suggestions made for a more standardised approach.

  1. Photonuclear reactions on titanium isotopes

    SciTech Connect

    Belyshev, S. S.; Dzhilavyan, L. Z.; Ishkhanov, B. S.; Kapitonov, I. M.; Kuznetsov, A. A. Orlin, V. N.; Stopani, K. A.

    2015-03-15

    The photodisintegration of titanium isotopes in the giant-dipole-resonance energy region is studied by the photon-activation method. Bremsstrahlung photons whose spectrum has the endpoint energy of 55 MeV is used. The yields and integrated cross sections are determined for photoproton reactions on the titanium isotopes {sup 47,48,49,50}Ti. The respective experimental results are compared with their counterparts calculated on the basis of the TALYS code and a combined photonucleon-reaction model. The TALYS code disregards the isospin structure of the giant dipole resonance and is therefore unable to describe the yield of photoproton reactions on the heavy titanium isotopes {sup 49,50}Ti.

  2. Isotope specific arbitrary material sorter

    SciTech Connect

    Barty, Christopher P.J.

    2015-12-08

    A laser-based mono-energetic gamma-ray source is used to provide a rapid and unique, isotope specific method for sorting materials. The objects to be sorted are passed on a conveyor in front of a MEGa-ray beam which has been tuned to the nuclear resonance fluorescence transition of the desired material. As the material containing the desired isotope traverses the beam, a reduction in the transmitted MEGa-ray beam occurs. Alternately, the laser-based mono-energetic gamma-ray source is used to provide non-destructive and non-intrusive, quantitative determination of the absolute amount of a specific isotope contained within pipe as part of a moving fluid or quasi-fluid material stream.

  3. The terrestrial uranium isotope cycle.

    PubMed

    Andersen, Morten B; Elliott, Tim; Freymuth, Heye; Sims, Kenneth W W; Niu, Yaoling; Kelley, Katherine A

    2015-01-15

    Changing conditions on the Earth's surface can have a remarkable influence on the composition of its overwhelmingly more massive interior. The global distribution of uranium is a notable example. In early Earth history, the continental crust was enriched in uranium. Yet after the initial rise in atmospheric oxygen, about 2.4 billion years ago, the aqueous mobility of oxidized uranium resulted in its significant transport to the oceans and, ultimately, by means of subduction, back to the mantle. Here we explore the isotopic characteristics of this global uranium cycle. We show that the subducted flux of uranium is isotopically distinct, with high (238)U/(235)U ratios, as a result of alteration processes at the bottom of an oxic ocean. We also find that mid-ocean-ridge basalts (MORBs) have (238)U/(235)U ratios higher than does the bulk Earth, confirming the widespread pollution of the upper mantle with this recycled uranium. Although many ocean island basalts (OIBs) are argued to contain a recycled component, their uranium isotopic compositions do not differ from those of the bulk Earth. Because subducted uranium was probably isotopically unfractionated before full oceanic oxidation, about 600 million years ago, this observation reflects the greater antiquity of OIB sources. Elemental and isotope systematics of uranium in OIBs are strikingly consistent with previous OIB lead model ages, indicating that these mantle reservoirs formed between 2.4 and 1.8 billion years ago. In contrast, the uranium isotopic composition of MORB requires the convective stirring of recycled uranium throughout the upper mantle within the past 600 million years.

  4. The terrestrial uranium isotope cycle

    NASA Astrophysics Data System (ADS)

    Andersen, Morten B.; Elliott, Tim; Freymuth, Heye; Sims, Kenneth W. W.; Niu, Yaoling; Kelley, Katherine A.

    2015-01-01

    Changing conditions on the Earth's surface can have a remarkable influence on the composition of its overwhelmingly more massive interior. The global distribution of uranium is a notable example. In early Earth history, the continental crust was enriched in uranium. Yet after the initial rise in atmospheric oxygen, about 2.4 billion years ago, the aqueous mobility of oxidized uranium resulted in its significant transport to the oceans and, ultimately, by means of subduction, back to the mantle. Here we explore the isotopic characteristics of this global uranium cycle. We show that the subducted flux of uranium is isotopically distinct, with high 238U/235U ratios, as a result of alteration processes at the bottom of an oxic ocean. We also find that mid-ocean-ridge basalts (MORBs) have 238U/235U ratios higher than does the bulk Earth, confirming the widespread pollution of the upper mantle with this recycled uranium. Although many ocean island basalts (OIBs) are argued to contain a recycled component, their uranium isotopic compositions do not differ from those of the bulk Earth. Because subducted uranium was probably isotopically unfractionated before full oceanic oxidation, about 600 million years ago, this observation reflects the greater antiquity of OIB sources. Elemental and isotope systematics of uranium in OIBs are strikingly consistent with previous OIB lead model ages, indicating that these mantle reservoirs formed between 2.4 and 1.8 billion years ago. In contrast, the uranium isotopic composition of MORB requires the convective stirring of recycled uranium throughout the upper mantle within the past 600 million years.

  5. AVLIS enrichment of medical isotopes

    SciTech Connect

    Haynam, C.A.; Scheibner, K.F.; Stern, R.C.; Worden, E.F.

    1996-12-31

    Under the Sponsorship of the United states Enrichment Corporation (USEC), we are currently investigating the large scale separation of several isotopes of medical interest using atomic vapor isotope separation (AVLIS). This work includes analysis and experiments in the enrichment of thallium 203 as a precursor to the production of thallium 201 used in cardiac imaging following heart attacks, on the stripping of strontium 84 from natural strontium as precursor to the production of strontium 89, and on the stripping of lead 210 from lead used in integrated circuits to reduce the number of alpha particle induced logic errors.

  6. APPLICATIONS OF ENVIRONMENTAL ISOTOPES FOR WATERSHED INVESTIGATIONS

    EPA Science Inventory

    Environmental isotopes include naturally-occurring nuclides that can be applied as tracers within watersheds (Sidle, 1998). Recent advances in mass spectroscopy may supplant many traditional and costly hydrometric techniques. It is now possible, for example, to utilize isotopes a...

  7. Iron Isotope Systematics of Refractory Inclusions

    NASA Astrophysics Data System (ADS)

    Shollenberger, Q. R.; Brennecka, G. A.; Schuth, S.; Weyer, S.

    2016-08-01

    CAIs from CV3 and CK meteorites are investigated for their Fe isotopic compositions. Some CAIs show correlated mass-dependent and mass-independent Fe isotopic variations, indicating possible mixing between the original CAI Fe and the host rock.

  8. Feasibility of Isotopic Measurements: Graphite Isotopic Ratio Method

    SciTech Connect

    Wood, Thomas W.; Gerlach, David C.; Reid, Bruce D.; Morgan, W. C.

    2001-04-30

    This report addresses the feasibility of the laboratory measurements of isotopic ratios for selected trace constituents in irradiated nuclear-grade graphite, based on the results of a proof-of-principal experiment completed at Pacific Northwest National Laboratory (PNNL) in 1994. The estimation of graphite fluence through measurement of isotopic ratio changes in the impurity elements in the nuclear-grade graphite is referred to as the Graphite Isotope Ratio Method (GIRM). Combined with reactor core and fuel information, GIRM measurements can be employed to estimate cumulative materials production in graphite moderated reactors. This report documents the laboratory procedures and results from the initial measurements of irradiated graphite samples. The irradiated graphite samples were obtained from the C Reactor (one of several production reactors at Hanford) and from the French G-2 Reactor located at Marcoule. Analysis of the irradiated graphite samples indicated that replicable measurements of isotope ratios could be obtained from the fluence sensitive elements of Ti, Ca, Sr, and Ba. While these impurity elements are present in the nuclear-grade graphite in very low concentrations, measurement precision was typically on the order of a few tenths of a percent to just over 1 percent. Replicability of the measurements was also very good with measured values differing by less than 0.5 percent. The overall results of this initial proof-of-principal experiment are sufficiently encouraging that a demonstration of GIRM on a reactor scale basis is planned for FY-95.

  9. Online Catalog of Isotope Products from DOE's National Isotope Development Center

    DOE Data Explorer

    The National Isotope Development Center (NIDC) interfaces with the User Community and manages the coordination of isotope production across the facilities and business operations involved in the production, sale, and distribution of isotopes. A virtual center, the NIDC is funded by the Isotope Development and Production for Research and Applications (IDPRA) subprogram of the Office of Nuclear Physics in the U.S. Department of Energy Office of Science. The Isotope subprogram supports the production, and the development of production techniques of radioactive and stable isotopes that are in short supply for research and applications. Isotopes are high-priority commodities of strategic importance for the Nation and are essential for energy, medical, and national security applications and for basic research; a goal of the program is to make critical isotopes more readily available to meet domestic U.S. needs. This subprogram is steward of the Isotope Production Facility (IPF) at Los Alamos National Laboratory (LANL), the Brookhaven Linear Isotope Producer (BLIP) facility at BNL, and hot cell facilities for processing isotopes at ORNL, BNL and LANL. The subprogram also coordinates and supports isotope production at a suite of university, national laboratory, and commercial accelerator and reactor facilities throughout the Nation to promote a reliable supply of domestic isotopes. The National Isotope Development Center (NIDC) at ORNL coordinates isotope production across the many facilities and manages the business operations of the sale and distribution of isotopes.

  10. Magnesium isotope fractionation during continental weathering

    NASA Astrophysics Data System (ADS)

    Teng, F. Z.; Huang, K. J.; Li, W.; Liu, X. M.; Ma, L.

    2014-12-01

    Continental weathering links the atmosphere, hydrosphere and continents as it regulates the CO2 content of the atmosphere, shifts the composition of the continental crust from basaltic to andesitic, and ultimately controls the chemical composition of river waters and seawater. Magnesium is a water-soluble major element in the hydrosphere, continental crust and the mantle, and has three stable isotopes (24Mg, 25Mg and 26Mg). Studies of Mg isotopes during continental weathering may help to document the interactions between hydrosphere, crust and mantle. Previous studies have shown that the continental crust has a heterogeneous but on average heavier Mg isotopic composition than the mantle, whereas the hydrosphere is isotopically light. The complementary characteristics of Mg isotopic compositions between continental and hydrosphere have been attributed to continental weathering, with light Mg isotopes partitioned into water, leaving heavy Mg isotopes behind in the crustal residue. Here we summarize our studies of Mg isotope fractionation in four weathering profiles under various climate conditions. We show that large Mg isotope fractionation can occur during continental weathering. Although the weathered residue is usually enriched in heavier Mg isotopes than unaltered parent rocks, some heavily weathered products can be quite light in Mg isotopic composition. The complicated behaviors of Mg isotopes reflect different control factors during weathering such as parent rock lithology, primary mineral dissolution, secondary mineral formation, ion exchange, vegetation uptake etc. Though studies of natural samples can provide direct evidence on isotope fractionation, more well-controlled laboratory experiments on Mg isotope fractionation between fluids and minerals are needed in order to fully understand the behaviors of Mg isotopes during weathering, which ultimately lays the foundation for making Mg isotope geochemistry an important tool for studying different geological

  11. The separation of stable isotopes of carbon

    NASA Astrophysics Data System (ADS)

    Oziashvili, E. D.; Egiazarov, A. S.

    1989-04-01

    The present state of work on the separation of carbon isotopes by diffusion, fractional distillation, chemical isotopic exchange, and the selective excitation and dissociation of molecules in electrical discharges or in the field of laser radiation has been examined. The characteristics of new laboratory and industrial assemblies for separating carbon isotopes have been described. Promising directions of study aimed at developing effective technological processes for separating carbon isotopes have been noted. The bibliography contains 148 references.

  12. Measured solubilities and speciations of neptunium, plutonium, and americium in a typical groundwater (J-13) from the Yucca Mountain region; Milestone report 3010-WBS 1.2.3.4.1.3.1

    SciTech Connect

    Nitsche, H.; Gatti, R.C.; Standifer, E.M.

    1993-07-01

    Solubility and speciation data are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, {sup 241}Am{sup 3+}/Nd{sup 3+}, and {sup 243}Am{sup 3+} in J-13 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at three different temperatures (25{degree}, 60{degree}, and 90{degree}C) and pH values (5.9, 7.0, and 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations decreased with increasing temperature and showed no trend with pH. The americium solutions showed no clear solubility trend with increasing temperature and increasing pH.

  13. Measured solubilities and speciations from oversaturation experiments of neptunium, plutonium, and americium in UE-25p No. 1 well water from the Yucca Mountain region: Milestone report 3329-WBS1.2.3.4.1.3.1

    SciTech Connect

    Nitsche, H.; Roberts, K.; Prussin, T.; Mueller, A.; Becraft, K.; Keeney, D.; Carpenter, S.A.; Gatti, R.C.

    1994-04-01

    Solubility and speciation are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are a part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, and {sup 241}Am{sup 3+}/Nd{sup 3+} in a modified UE-25p No. 1 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at two different temperatures (25{degree} and 60{degree}C) and three pH values (6.0, 7.0, 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations significantly decreased with increasing temperature at pH 6 and 7. The concentration at pH 8.5 hardly decreased at all with increasing temperature. At both temperatures the concentrations were highest at pH 8.5, lowest at pH 7, and in between at pH 6. For the americium/neodymium solutions, the solubility decreased significantly with increasing temperature and increased somewhat with increasing pH.

  14. Dry phase reactor for generating medical isotopes

    DOEpatents

    Mackie, Thomas Rockwell; Heltemes, Thad Alexander

    2016-05-03

    An apparatus for generating medical isotopes provides for the irradiation of dry-phase, granular uranium compounds which are then dissolved in a solvent for separation of the medical isotope from the irradiated compound. Once the medical isotope is removed, the dissolved compound may be reconstituted in dry granular form for repeated irradiation.

  15. ICP-MS for isotope ratio measurement

    USDA-ARS?s Scientific Manuscript database

    The use of stable isotopes in mineral nutrition research has become a fundamental aspect of conducting this research. A gradual transition has occurred, now virtually complete, from radioactive isotope studies to those using stable isotopes. Although primarily used in human research, mineral stable ...

  16. Substitution of stable isotopes in Chlorella

    NASA Technical Reports Server (NTRS)

    Flaumenhaft, E.; Katz, J. J.; Uphaus, R. A.

    1969-01-01

    Replacement of biologically important isotopes in the alga Chlorella by corresponding heavier stable isotopes produces increasingly greater deviations from the normal cell size and changes the quality and distribution of certain cellular components. The usefulness of isotopically altered organisms increases interest in the study of such permuted organisms.

  17. Isotope Cancer Treatment Research at LANL

    ScienceCinema

    Weidner, John; Nortier, Meiring

    2016-07-12

    Los Alamos National Laboratory has produced medical isotopes for diagnostic and imaging purposes for more than 30 years. Now LANL researchers have branched out into isotope cancer treatment studies. New results show that an accelerator-based approach can produce clinical trial quantities of actinium-225, an isotope that has promise as a way to kill tumors without damaging surrounding healthy cells.

  18. Isotope Cancer Treatment Research at LANL

    SciTech Connect

    Weidner, John; Nortier, Meiring

    2012-04-11

    Los Alamos National Laboratory has produced medical isotopes for diagnostic and imaging purposes for more than 30 years. Now LANL researchers have branched out into isotope cancer treatment studies. New results show that an accelerator-based approach can produce clinical trial quantities of actinium-225, an isotope that has promise as a way to kill tumors without damaging surrounding healthy cells.

  19. Martian Volatiles and Isotopic Signatures

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    1997-01-01

    Data on martian volatiles gathered from Viking atmosphere measurements, modest groundbased spectra, shock-implanted atmospheric gases in martian (SNC) meteorites, trapped mantle gases in martian meteorites, and volatile-rich solid phases in martian meteorites, are presented. Atmospheric volatiles, surface volatiles, and isotopic chronologies are discussed, along with energetic particle interactions.

  20. Nuclear fission of Fm isotopes

    SciTech Connect

    Asano, T.; Wada, T.; Ohta, M.; Chiba, S.

    2010-06-01

    Multi-modal fission has been systematically investigated for the series of isotopes of Fm and Cf. The multi-dimensional Langevin-type stochastic differential equation is used for the dynamical calculation. The primary fission mode changes from mass-asymmetric fission to mass-symmetric fission with the increase of neutron numbers for both Fm and Cf cases.

  1. Isotope Harvesting Opportunities at FRIB

    NASA Astrophysics Data System (ADS)

    Morrissey, David

    2017-01-01

    The fragmentation of fast heavy ion beams now at the National Superconducting Cyclotron Laboratory (NSCL) and in the future at the Facility for Rare Isotope Beams (FRIB) under construction produce an unprecedentedly broad spectrum of radionuclides but only a small fraction are used in the on-line rare-isotope program. Projectile fragmentation facilities provide an electromagnetically purified beam of a single projectile fragment for nuclear physics experiments ranging from low energy astrophysics, through nuclear structure studies, to probing fundamental symmetries. By augmenting the NSCL and FRIB production facilities with complimentary collection and purification of discarded ions, called isotope harvesting with chemical purification, many other nuclides will become available for off-line experiments in parallel with the primary experiment. A growing user community has established a list of key target isotopes and is working with the FRIB design team to allow inclusion of necessary equipment in the future. An overview of the possibilities and the techniques will be presented in this talk. Supported by Office of Science, US DOE and Michigan State University.

  2. Bayesian stable isotope mixing models

    EPA Science Inventory

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...

  3. Isotope geochemistry in 1990s

    SciTech Connect

    Billo, S.M.

    1995-12-31

    The intense interest in radioactive minerals as a source of atomic energy, and their application in searching for ore deposits and also in gamma-ray and neutron logging oil wells, have opened new vistas in every science. Many minerals containing elements of high atomic weight are radioactive, and emit a radiation which affects a photographic plate and may be detected by means of a sensitive phosphorescent screen. Most of the elements as found in nature are a mixture of isotopes. isotopes are atoms of one element which have different masses. Uranium, thorium, potassium, and rubidium isotopes are also used to date minerals and rocks. Organic materials that have been in equilibrium with CO{sub 2}-photosynthetic cycle during the past 50,000 years are dated by carbon-14 method. The stable isotopes of H{sub 2}, C, N{sub 2}, O{sub 2}, and S are intimately associated with the atmosphere, hydrosphere, and lithosphere and are used in probing water resources.

  4. Progress in tropical isotope dendroclimatology

    NASA Astrophysics Data System (ADS)

    Evans, M. N.; Schrag, D. P.; Poussart, P. F.; Anchukaitis, K. J.

    2005-12-01

    The terrestrial tropics remain an important gap in the growing high resolution proxy network used to characterize the mean state and variability of the hydrological cycle. Here we review early efforts to develop a new class of proxy paleorainfall/humidity indicators using intraseasonal to interannual-resolution stable isotope data from tropical trees. The approach invokes a recently published model of oxygen isotopic composition of alpha-cellulose, rapid methods for cellulose extraction from raw wood, and continuous flow isotope ratio mass spectrometry to develop proxy chronological, rainfall and growth rate estimates from tropical trees, even those lacking annual rings. Isotopically-derived age models may be confirmed for modern intervals using trees of known age, radiocarbon measurements, direct measurements of tree diameter, and time series replication. Studies are now underway at a number of laboratories on samples from Costa Rica, northwestern coastal Peru, Indonesia, Thailand, New Guinea, Paraguay, Brazil, India, and the South American Altiplano. Improved sample extraction chemistry and online pyrolysis techniques should increase sample throughput, precision, and time series replication. Statistical calibration together with simple forward modeling based on the well-observed modern period can provide for objective interpretation of the data. Ultimately, replicated data series with well-defined uncertainties can be entered into multiproxy efforts to define aspects of tropical hydrological variability associated with ENSO, the meridional overturning circulation, and the monsoon systems.

  5. Bayesian stable isotope mixing models

    EPA Science Inventory

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...

  6. Isotope separation by laser technology

    NASA Astrophysics Data System (ADS)

    Stoll, Wolfgang

    2002-03-01

    Isotope separation processes operate on very small differences, given either by the Quotient of masses with the same number of electrons or by their mass difference. When separating isotopes of light elements in mass quantities, thermodynamic processes accounting for the quotient, either in diffusion, chemical reactivity or distillation are used. For heavy elements those quotients are very small. Therefore they need a large number of separation steps. Large plants with high energy consumption result from that. As uranium isotope separation is the most important industrial field, alternatives, taking account for the mass difference, as e.g. gas centrifuges, have been developed. They use only a fraction of the energy input, but need a very large number of machines, as the individual throughput is small. Since it was discovered, that molecules of high symmetry like Uranium-Hexafluoride as a deep-cooled gas stream can be ionized by multiple photon excitation, this process was studied in detail and in competition to the selective ionization of metal vapors, as already demonstrated with uranium. The paper reports about the principles of the laser excitation for both processes, the different laboratory scale and prototypical plants built, the difficulties with materials, as far as the metal vapor laser separation is concerned, and the difficulties experienced in the similarity in molecular spectra. An overview of the relative economic merits of the different processes and the auspices in a saturated market for uranium isotope separation, together with other potential markets for molecular laser separation, is contained in the conclusions.

  7. Isotopic Fractionation in Interstellar Chemistry

    NASA Technical Reports Server (NTRS)

    Charnley, Steven

    2009-01-01

    Isotopically fractionated material is found in many solar system objects, including meteorites and comets. It is thought, in some cases, to trace interstellar material that was incorporated into the solar sys tem without undergoing significant processing. In this poster, we sho w the results of several models of the nitrogen, oxygen, and carbon f ractionation in proto-stellar cores.

  8. A NICHE FOR ISOTOPIC ECOLOGY

    EPA Science Inventory

    Fifty years ago, GE Hutchinson defined the ecological niche as a hypervolume in n-dimensional space with environmental variables as axes. Ecologists have recently developed renewed interest in the concept, and technological advances now allow us to use stable isotope analyses to ...

  9. Oxygen isotope geochemistry of zircon

    NASA Astrophysics Data System (ADS)

    Valley, John W.; Chiarenzelli, Jeffrey R.; McLelland, James M.

    1994-09-01

    The high-temperature and small sample size of an I.R. laser system has allowed the first detailed study of oxygen isotope ratios in zircon. Low-magnetism zircons that have grown during metamorphism in the Adirondack Mts., N.Y. preserve primary delta (O-18) values and low magnetism igneous zircons are likewise primary, showing no significant affect due to subsequent granulite facies metamorphism. The measured fractionation between zircon and garnet is delta (Gt-Zrc) = 0.0 + or - 0.2/mil (1(sigma)) for most low-magnetism zircons in meta-igneous rocks. The consistency of this value indicates equilibration at temperatures of 700 - 1100 C and little or no change in the equilibrium fractionation over this temperature range. In contrast, detrital low-magnetism zircons in quartzite preserve igneous compositions, up to 4/mil out of equilibrium with host quartz, in spite of granulite facies metamorphism. The oxygen isotope composition of zircon can be linked to U-Pb ages and can `see through' metamorphism, providing a new tool for deciphering complex igneous, metamorphic and hydrothermal histories. Zircons separated by magnetic susceptibility show a consistent correlation. Low-magnetism zircons have the lowest uranium contents, the most concordant U-Pb isotopic compositions, and primary delta (O-18) values. In contrast, high-magnetism zircons are up to 2/mil lower in delta (O-18) than low-magnetism zircons from the same rock. The resetting of oxygen isotope ratios in high-magnetism zircons is caused by radiation damage which creates microfractures and enhances isotopic exchange. Zircons from the metamorphosed anorthosite-mangerite-charnocite-granite (AMCG) suite of adirondacks have previously been dated (1125-1157 Ma) and classified as igneous, metamorphic or disturbed based on their physical and U-Pb isotopic characteristics. Low-magnetism zircons from the AMCG suite have high, nearly constant values of delta (O-18) that average 8.1 + or - 0.4/mil(1 sigma) for samples

  10. Stable Isotope Analysis of Chlorate

    NASA Astrophysics Data System (ADS)

    Brundrett, M.; Jackson, W. A.; Sturchio, N. C.; Bohlke, J. K.; Hatzinger, P.

    2016-12-01

    Studies have confirmed the presence of chlorate (ClO3-) throughout terrestrial and extraterrestrial systems generally in excess of perchlorate (ClO4-) [1, 2]. ClO3- occurrence, production, and post depositional transformation has significant implications to our understanding of atmospheric Cl cycling and potential biogeochemical reactions on Earth and Mars. The isotopic composition of oxyanions can be used to evaluate their production mechanisms and post-depositional alteration [3, 4]. However, no information is available on the natural isotopic composition of ClO3-. The objective of this study was to develop a method to measure the stable isotope composition (δ18O, δ17O and δ37Cl) of ClO3- and to determine the isotopic composition of ClO3- in natural desert salt accumulations that have been studied previously for NO3- and ClO4- isotopic composition. The process of ClO3- purification and analysis of δ18O, δ 17O and δ37Cl is problematic but has recently been resolved by adapting previously published methods for ClO4-. Competitive anions (e.g. NO3-, Cl-, ClO4-, and SO4-2) are removed through a series of processes including biological reduction, solid phase extraction, and anion or cation exchange. Initial results for control samples treated with the above method have a maximum variation of ± 2 ‰. These methods are being applied to representative samples to determine if various sources of natural and synthetic ClO3- have distinctive isotopic compositions, as reported previously for ClO4- [3, 4]. Establishing the range of isotopic composition of natural ClO3- also could provide information about atmospheric ClO3- production mechanisms and post-depositional processing, with implications for the atmospheric chemistry of oxychlorine compounds and the global biogeochemical cycling of Cl. [1] Jackson et al. (2015) EPSL 430, 470-476. [2] Rao et al. (2010) ES&T 44, 8429-8434. [3] Jackson et al. (2010) ES&T 44, 4869-4876. [4] Bao and Gu (2004) ES&T 38, 5073-5077.

  11. Oxygen Isotopic Compositions of Fulgurites

    NASA Astrophysics Data System (ADS)

    Robert, F.; Javoy, M.

    1992-07-01

    Two occurrences of vitreous rocks (fulgurites) that have resulted from the fusion of Etnean lavas, have been ascribed to the result of lightning striking the basalts and melting fresh volcanic rocks [1]. Rapidly quenched melts appear as tubular cavities that preserve the path of the discharge. Glass droplets (D <= 500 micrometers) are always dispersed around the fused lava tube and show several petrographic similarities with chondrules found in ordinary chondrites (presence of melilite, radiating skeletal fassaite, etc). In this process, high temperatures (T>1800 K) have probably been reached during timescales <=10 sec. Because it has been suggested that lightning discharges may have played an important role in the formation of chondrules [2], we have analyzed the oxygen isotope compositions of these fulgurites (our experimental protocol is described elsewhere [3]). The glass (free from any contamination from the unmelted basalt) is 1.5o/oo depleted in ^18O relative to its measured initial isotopic composition (delta^18O = +5.6o/oo); most of the data define a mass-dependent fractionation relationship (i.e. delta^17O = 0.52 x delta^18O). Therefore the data clearly do not reproduce the oxygen isotope anomaly defined for meteorites, which has a slope of 1 in the diagram delta^17O versus delta^18O (i.e. delta^17O = 1.0 x delta^18O). Nevertheless, it should be noted that some glass samples scatter around this canonical value of 0.52 with minor departures from a purely mass-dependent fractionation. If these results are confirmed by additional determinations (now in progress) on the separated glassy droplets, the following conclusions can be proposed: 1) lightning discharges do not yield oxygen isotope anomalies similar to those measured in chondrules and 2) an isotope exchange between hot chondrules and their parent nebular gas--presumably "anomalous" in its oxygen isotopes-- seems difficult to achieve within the duration of the rapid cooling of the melt. This last point

  12. Calcium isotope analysis by mass spectrometry.

    PubMed

    Boulyga, Sergei F

    2010-01-01

    The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. The present article discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. In Sections 2 and 3, mass spectrometric methods applied to precise stable isotope analysis and to the determination of (41)Ca are described. Section 4 contains a short summary of selected applications, and includes tracer experiments and the potential use

  13. Uncertainty induced by chest wall thickness assessment methods on lung activity estimation for plutonium and americium: a large population-based study.

    PubMed

    Broggio, D; Lechaftois, X; Franck, D

    2015-03-01

    In vivo lung counting aims at assessing the retained activity in the lungs. The calibration factor relating the measured counts to the worker's specific retained lung activity can be obtained by several means and strongly depends on the chest wall thickness. Here we compare, for 374 male nuclear workers, the activity assessed with a reference protocol, where the material equivalent chest wall thickness is known from ultrasound measurements, with two other protocols. The counting system is an array of four germanium detectors.It is found that non site-specific equations for the assessment of the chest wall thickness induce large biases in the assessment of activity. For plutonium isotopes or (241)Am the proportion of workers for whom the retained activity is within ± 10% of the reference one is smaller than 10%.The use of site-specific equations raises this proportion to 20% and 58% for plutonium and (241)Am, respectively.Finally, for the studied population, when site-specific equations are used for the chest wall thickness, the standard uncertainties for the lung activity are 42% and 12.5%, for plutonium and (241)Am, respectively. Due to the relatively large size of the studied population, these values are a relatively robust estimate of the uncertainties due to the assessment of the chest wall thickness for the current practice at this site.

  14. A global Ge isotope budget

    NASA Astrophysics Data System (ADS)

    Baronas, J. Jotautas; Hammond, Douglas E.; McManus, James; Wheat, C. Geoffrey; Siebert, Christopher

    2017-04-01

    We present measurements of Ge isotope composition and ancillary data for samples of river water, low- and high-temperature hydrothermal fluids, and seawater. The dissolved δ74Ge composition of analyzed rivers ranges from 2.0 to 5.6‰, which is significantly heavier than previously determined values for silicate rocks (δ74Ge = 0.4-0.7‰, Escoube et al., Geostand. Geoanal. Res., 36(2), 2012) from which dissolved Ge is primarily derived. An observed negative correlation between riverine Ge/Si and δ74Ge signatures suggests that the primary δ74Ge fractionation mechanism during rock weathering is the preferential incorporation of light isotopes into secondary weathering products. High temperature (>150 °C) hydrothermal fluids analyzed in this study have δ74Ge of 0.7-1.6‰, most likely fractionated during fluid equilibration with quartz in the reaction zone. Low temperature (25-63 °C) hydrothermal fluids are heavier (δ74Ge between 2.9‰ and 4.1‰) and most likely fractionated during Ge precipitation with hydrothermal clays. Seawater from the open ocean has a δ74Gesw value of 3.2 ± 0.4‰, and is indistinguishable among the different ocean basins at the current level of precision. This value should be regulated over time by the isotopic balance of Ge sources and sinks, and a new compilation of these fluxes is presented, along with their estimated isotopic compositions. Assuming steady-state, non-opal Ge sequestration during sediment authigenesis likely involves isotopic fractionation Δ74Gesolid-solution that is -0.6 ± 1.8‰.

  15. Isotopic anomalies - Chemical memory of Galactic evolution

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.

    1988-01-01

    New mechanisms for the chemical memory of isotopic anomalies are proposed which are based on the temporal change during the chemical evolution of the Galaxy of the isotopic composition of the mean ejecta from stars. Because of the differing temporal evolution of primary and secondary products of nucleosynthesis, the isotopic composition of the bulk interstellar medium changes approximately linearly with time, and thus any dust component having an age different from that of average dust will be isotopically anomalous. Special attention is given to C, O, Mg, Si, and isotopically heavy average-stellar condensates of SiC.

  16. Isotopic Compositions of the Elements, 2001

    NASA Astrophysics Data System (ADS)

    Böhlke, J. K.; de Laeter, J. R.; De Bièvre, P.; Hidaka, H.; Peiser, H. S.; Rosman, K. J. R.; Taylor, P. D. P.

    2005-03-01

    The Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry completed its last review of the isotopic compositions of the elements as determined by isotope-ratio mass spectrometry in 2001. That review involved a critical evaluation of the published literature, element by element, and forms the basis of the table of the isotopic compositions of the elements (TICE) presented here. For each element, TICE includes evaluated data from the "best measurement" of the isotope abundances in a single sample, along with a set of representative isotope abundances and uncertainties that accommodate known variations in normal terrestrial materials. The representative isotope abundances and uncertainties generally are consistent with the standard atomic weight of the element Ar(E) and its uncertainty U[Ar(E)] recommended by CAWIA in 2001.

  17. Heavy atom isotope effects on enzymatic reactions

    NASA Astrophysics Data System (ADS)

    Paneth, Piotr

    1994-05-01

    The theory of isotope effects, which has proved to be extremely useful in providing geometrical details of transition states in a variety of chemical reactions, has recently found an application in studies of enzyme-catalyzed reactions. These reactions are multistep in nature with few steps being partially rate-limiting, thus interpretation of these isotope effects is more complex. The theoretical framework of heavy-atom isotope effects on enzymatic reactions is critically analyzed on the basis of recent results of: carbon kinetic isotope effects on carbonic anhydrase and catalytic antibodies; multiple carbon, deuterium isotope effects on reactions catalyzed by formate decarboxylase; oxygen isotope effects on binding processes in reactions catalyzed by pyruvate kinase; and equilibrium oxygen isotope effect on binding an inhibitor to lactate dehydrogenase. The advantages and disadvantages of reaction complexity in learning details of formal and molecular mechanisms are discussed in the examples of reactions catalyzed by phosphoenolpyruvate carboxylase, orotidine decarboxylase and glutamine synthetase.

  18. Measuring SNM Isotopic Distributions using FRAM

    SciTech Connect

    Geist, William H.

    2015-12-02

    The first group of slides provides background information on the isotopic composition of plutonium. It is shown that 240Pu is the critical isotope in neutron coincidence/multiplicity counting. Next, response function analysis to determine isotopic composition is discussed. The isotopic composition can be determined by measuring the net peak counts from each isotope and then taking the ratio of the counts for each isotope relative to the total counts for the element. Then FRAM (Fixed energy Response function Analysis with Multiple efficiencies) is explained. FRAM can control data acquisition, automatically analyze newly acquired data, analyze previously acquired data, provide information on the quality of the analysis, and facilitate analysis in unusual situations (non-standard energy calibrations, gamma rays from non-SNM isotopes, poor spectra (within limits)).

  19. Zinc isotopic compositions of breast cancer tissue.

    PubMed

    Larner, Fiona; Woodley, Laura N; Shousha, Sami; Moyes, Ashley; Humphreys-Williams, Emma; Strekopytov, Stanislav; Halliday, Alex N; Rehkämper, Mark; Coombes, R Charles

    2015-01-01

    An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.

  20. Isotopic compositions of the elements, 2001

    USGS Publications Warehouse

    Böhlke, J.K.; De Laeter, J. R.; De Bievre, P.; Hidaka, H.; Peiser, H.S.; Rosman, K.J.R.; Taylor, P.D.P.

    2005-01-01

    The Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry completed its last review of the isotopic compositions of the elements as determined by isotope-ratio mass spectrometry in 2001. That review involved a critical evaluation of the published literature, element by element, and forms the basis of the table of the isotopic compositions of the elements (TICE) presented here. For each element, TICE includes evaluated data from the "best measurement" of the isotope abundances in a single sample, along with a set of representative isotope abundances and uncertainties that accommodate known variations in normal terrestrial materials. The representative isotope abundances and uncertainties generally are consistent with the standard atomic weight of the element A r(E) and its uncertainty U[Ar(E)] recommended by CAWIA in 2001. ?? 2005 American Institute of Physics.

  1. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    SciTech Connect

    Nimz, G. J., LLNL

    1998-06-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

  2. Isotopic enrichment of uranium with respect to an isotope

    SciTech Connect

    Delvalle, P.

    1980-12-02

    A process for chemical enrichment of uranium with respect to a lighter one of its isotopes. The process consists in contacting uranium of valence state III and uranium of valence state IV, or a compound of uranium of valence state III and a different compound of uranium of valence state III. One of the phases which are contacted or the only phase is liquid. The system should be substantially free of elements which would cause uranium III to oxidize to valence IV.

  3. Strontium Isotopes and Magma Dynamics

    NASA Astrophysics Data System (ADS)

    Wolff, J. A.; Ellis, B. S.; Ramos, F. C.

    2010-12-01

    Over the past decade, it has become clear that volcanic rocks commonly exhibit internal heterogeneity in radiogenic isotopes. In particular, strontium isotopic disequilibrium between co-exisitng phenocrysts, between phenocrysts and matrix, and isotopic zoning within single crystals has been demonstrated in basalts, andesites, dacites, rhyolites and alkaline magmas; in some cases, the range in 87Sr/86Sr among different components in the same rock may equal or exceed the bulk-rock range seen in the entire formation, volcanic center, or province. High-temperature “Snake River type” rhyolites appear to be an exception. Despite the occurrence of Snake River Plain rhyolites in a region of isotopically highly variable crust and mantle, and significant differences from rhyolite unit to rhyolite unit, internally they are near-homogeneous in 87Sr/86Sr. Little or no zoning is found within feldspar phenocrysts, and feldspars within a single unit are tightly grouped. Some units show minor contrasts between phenocrysts and matrix. High temperature rhyolitic magmas possess a unique combination of temperature and melt viscosity. Although they are typically 200°C hotter than common rhyolites, the effect on visocity is offset by lower water contents (~2 wt%), hence their melt viscosities are in the same range as common, water-rich, cool rhyolites (105 - 106 Pa s). Yet magmatic temperatures are in the same range as basaltic andesites and andesites, consequently cation diffusion rates in feldspar are 2 - 3 orders of magnitude greater than in common rhyolites. We hypothesize that this combination of characteristics promotes Sr isotopic homogeneity: high melt viscosities tend to inhibit crystal transfer and mixing of isotopically distinct components on timescales shorter than those required for diffusive homogenization of Sr between phenocrysts and matrix (100 - 1000 years). This is not the case for most magmas, in which either crystal transfer is rapid (<< 100 years) due to low

  4. Laser ablation molecular isotopic spectrometry of carbon isotopes

    NASA Astrophysics Data System (ADS)

    Bol‧shakov, Alexander A.; Mao, Xianglei; Jain, Jinesh; McIntyre, Dustin L.; Russo, Richard E.

    2015-11-01

    Quantitative determination of carbon isotopes using Laser Ablation Molecular Isotopic Spectrometry (LAMIS) is described. Optical emission of diatomic molecules CN and C2 is used in these measurements. Two quantification approaches are presented: empirical calibration of spectra using a set of reference standards and numerical fitting of a simulated spectrum to the experimental one. Formation mechanisms of C2 and CN in laser ablation plasma are briefly reviewed to provide insights for implementation of LAMIS measurements. A simulated spectrum of the 12C2 Swan system was synthesized using four constituents within 473.5-476.5 nm. Simulation included three branches of 12C2 (1-0), branches R(0-0) and R(1-1), and branch P(9-8) of 12C2. Spectral positions of the tail lines in R(0-0) and R(1-1) were experimentally measured, since they were not accurately known before. The Swan band (1-0) of the isotopologue 13C12C was also simulated. Fitting to the experimental spectrum yielded the ratio 13C/12C = 1.08% in a good agreement with measurements by isotope ratio mass spectrometry. LAMIS promises to be useful in coal, oil and shale exploration, carbon sequestration monitoring, and agronomy studies.

  5. Lasers utilizing CO2 isotopes

    NASA Astrophysics Data System (ADS)

    Pechenin, Iu. V.; Domanov, M. S.

    1980-08-01

    The emission spectra and power characteristics of CW (C-12)(O-16)2, (C-13)(O-16)2, (C-12)(O-16)(O-18)2 and (C-12)(O-18) lasers are investigated. Laser output power is found to depend equally on the proportion of carbon and oxygen isotopes in the active medium for all isotopes except the asymmetrical (C-12)(O-16)(O-18), in which maximum output power is four to five times less due to the doubling of emission lines and limited enrichment caused by recombination into (C-12)(O-16)2 and (C-12)(O-18)2 molecules during discharge. The unsaturated gain is observed to increase linearly with enrichment, with that of nonsymmetrical molecules half that of the symmetrical molecules, while the maximum power output is independent of enrichment.

  6. Ternary Fission of CF Isotopes

    NASA Astrophysics Data System (ADS)

    Vermote, S.; Wagemans, C.; Serot, O.; Soldner, T.; Geltenbort, P.; Almahamid, I.; Lukens, W.; Floyd, J.

    2008-04-01

    During the last years, different Cm and Cf isotopes have been studied by our research group in the frame of a systematic investigation of gas emission characteristics in ternary fission. In this paper we report on the energy distribution and the emission probability of 3H, 4He and 6He particles emitted in neutron induced ternary fission of 249Cf and 251Cf. Both measurements were performed at the high flux reactor of the Institute Laue-Langevin (Grenoble, France), using suited ΔE-E telescope detectors, consisting of well-calibrated silicon surface barrier detectors. In this way, the available database can be expanded with new results for Z=98 isotopes, for which the information on neutron induced ternary fission is almost nonexistent. These measurements are important for the systematic investigation of gas emission characteristics in ternary fission.

  7. Interstellar Isotopes: Prospects with ALMA

    NASA Technical Reports Server (NTRS)

    Charnley Steven B.

    2010-01-01

    Cold molecular clouds are natural environments for the enrichment of interstellar molecules in the heavy isotopes of H, C, N and O. Anomalously fractionated isotopic material is found in many primitive Solar System objects, such as meteorites and comets, that may trace interstellar matter that was incorporated into the Solar Nebula without undergoing significant processing. Models of the fractionation chemistry of H, C, N and O in dense molecular clouds, particularly in cores where substantial freeze-out of molecules on to dust has occurred, make several predictions that can be tested in the near future by molecular line observations. The range of fractionation ratios expected in different interstellar molecules will be discussed and the capabilities of ALMA for testing these models (e.g. in observing doubly-substituted isotopologues) will be outlined.

  8. Isotopic variations in primitive meteorites

    NASA Astrophysics Data System (ADS)

    Clayton, R. N.

    1981-12-01

    Oxygen isotopic variations in carbonaceous chondrites and ordinary chondrites can each be interpreted as mixtures of two isotopically different reservoirs, one consisting of solids, enriched in O-16, the other of a gas, depleted in O-16 relative to terrestrial abundances. The data indicate a common source of the solids for each of the two classes of meteorites, but a different gas reservoir for each. These conditions might obtain in gaseous protoplanets. It is noted that radiogenic Mg-26 is variable in abundance among some classes of Allende inclusions, implying either nebular heterogeneity with respect to Al-26/Al-27 ratios or time differences of crystal formation. The presence of excess Ag-107 from decay of extinct Pd-107 corroborates the evidence from Mg-26 for a time interval of at most a few million years between the last nucleosynthetic event and the accretion of substantial bodies in the solar system.

  9. Interstellar Isotopes: Prospects with ALMA

    NASA Technical Reports Server (NTRS)

    Charnley Steven B.

    2010-01-01

    Cold molecular clouds are natural environments for the enrichment of interstellar molecules in the heavy isotopes of H, C, N and O. Anomalously fractionated isotopic material is found in many primitive Solar System objects, such as meteorites and comets, that may trace interstellar matter that was incorporated into the Solar Nebula without undergoing significant processing. Models of the fractionation chemistry of H, C, N and O in dense molecular clouds, particularly in cores where substantial freeze-out of molecules on to dust has occurred, make several predictions that can be tested in the near future by molecular line observations. The range of fractionation ratios expected in different interstellar molecules will be discussed and the capabilities of ALMA for testing these models (e.g. in observing doubly-substituted isotopologues) will be outlined.

  10. Isotopic ratios in planetary atmospheres.

    PubMed

    de Bergh, C

    1995-03-01

    Recent progress on measurements of isotopic ratios in planetary or satellite atmospheres include measurements of the D/H ratio in the methane of Uranus, Neptune and Titan and in the water of Mars and Venus. Implications of these measurements on our understanding of the formation and evolution of the planets and satellite are discussed. Our current knowledge of the carbon, nitrogen and oxygen isotopic ratios in the atmospheres of these planets, as well as on Jupiter and Saturn, is also reviewed. We finally show what progress can be expected in the very near future due to some new ground-based instrumentation particularly well suited to such studies, and to forthcoming space missions.

  11. Isotopic heterogeneity in volcanic rocks

    NASA Astrophysics Data System (ADS)

    Wolff, J. A.; Ramos, F. C.; Tollstrup, D. L.

    2003-04-01

    The growing microsample database on volcanic rocks is showing that isotopic disequilibrium between and among phenocryst phases, their melt inclusions, and groundmass is the rule rather than the exception. This applies even in cases of little or no petrographic evidence for disequilibrium. Erupted magmas must therefore be regarded, to some extent, as mechanical mixtures of isotopically distinct components assembled from different sources. The preservation of isotopic disequilibrium requires that the assembly takes place before diffusion can eradicate evidence of disequilibrium. For a wide range of magmas (mafic, intermediate and felsic, silica under- and oversaturated) from different volcano types (flood basalts, monogenetic cones, stratocones, silicic calderas) this timescale ranges from thousands of years down to one year or less, with no consistent pattern of mixing-to-eruption time vs. volcano or magma type. Among many issues arising from these findings, we note that estimation of magmatic temperatures from application of equilibrium thermodynamics to phenocryst assemblages in volcanic rocks should be approached with extreme caution. The isotope ratio variations observed among the components of a single volcanic rock sample, in most cases, indicate interaction between magma and the local wall-rock. This is consistent with the view that the vast majority of magmas undergo modification during transport through and residence within the crust. Three physical origins of heterogeneity have been proposed: melting of wallrock, magmatic recharge, and mixing of components within a magma chamber initially segregated into melt-rich and crystal-rich portions. Time constraints on preservation of disequilibrium imply either a causal link with eruption, or that these processes occur through the lifetime of a chamber.

  12. Isotope Labeling in Insect Cells

    PubMed Central

    Saxena, Krishna; Dutta, Arpana; Klein-Seetharaman, Judith

    2011-01-01

    Recent years have seen remarkable progress in applying nuclear magnetic resonance (NMR) spectroscopy to proteins that have traditionally been difficult to study due to issues with folding, posttranslational modification, and expression levels or combinations thereof. In particular, insect cells have proved useful in allowing large quantities of isotope-labeled, functional proteins to be obtained and purified to homogeneity, allowing study of their structures and dynamics by using NMR. Here, we provide protocols that have proven successful in such endeavors. PMID:22167667

  13. Analysis of hydrogen isotope mixtures

    DOEpatents

    Villa-Aleman, Eliel

    1994-01-01

    An apparatus and method for determining the concentrations of hydrogen isotopes in a sample. Hydrogen in the sample is separated from other elements using a filter selectively permeable to hydrogen. Then the hydrogen is condensed onto a cold finger or cryopump. The cold finger is rotated as pulsed laser energy vaporizes a portion of the condensed hydrogen, forming a packet of molecular hydrogen. The desorbed hydrogen is ionized and admitted into a mass spectrometer for analysis.

  14. Copper isotope signatures in modern marine sediments

    NASA Astrophysics Data System (ADS)

    Little, Susan H.; Vance, Derek; McManus, James; Severmann, Silke; Lyons, Timothy W.

    2017-09-01

    The development of metal stable isotopes as tools in paleoceanography requires a thorough understanding of their modern marine cycling. To date, no Cu isotope data has been published for modern sediments deposited under low oxygen conditions. We present data encompassing a broad spectrum of hydrographic and redox regimes, including continental margin and euxinic (sulphide-containing) settings. Taken together with previously published data from oxic settings, these data indicate that the modern oceanic sink for Cu has a surprisingly homogeneous isotopic composition of about +0.3‰ (δ65Cu, relative to NIST SRM976). We suggest that this signature reflects one of two specific water-column processes: (1) an equilibrium isotope fractionation between soluble, isotopically heavy, Cu complexed to strong organic ligands and an isotopically light pool sorbed to particles that deliver Cu to the sediment, or (2) an equilibrium isotope fractionation between the same isotopically heavy ligand-bound pool and the particle reactive free Cu2+ species, with the latter being scavenged by particulates and thereby delivered to the sediment. An output flux of about +0.3‰ into sediments is isotopically light relative to the known inputs to the ocean (at around +0.6‰) and the seawater value of +0.6 to +0.9‰, suggesting the presence of an as yet unidentified isotopically light source of Cu to the oceans. We hypothesize that this source may be hydrothermal, or may result from the partial dissolution of continentally derived particles.

  15. Comparative isotope ecology of African great apes.

    PubMed

    Oelze, Vicky M; Fahy, Geraldine; Hohmann, Gottfried; Robbins, Martha M; Leinert, Vera; Lee, Kevin; Eshuis, Henk; Seiler, Nicole; Wessling, Erin G; Head, Josephine; Boesch, Christophe; Kühl, Hjalmar S

    2016-12-01

    The isotope ecology of great apes is a useful reference for palaeodietary reconstructions in fossil hominins. As extant apes live in C3-dominated habitats, variation in isotope signatures is assumed to be low compared to hominoids exploiting C4-plant resources. However, isotopic differences between sites and between and within individuals are poorly understood due to the lack of vegetation baseline data. In this comparative study, we included all species of free-ranging African great apes (Pan troglodytes, Pan paniscus, Gorilla sp.). First, we explore differences in isotope baselines across different habitats and whether isotopic signatures in apes can be related to feeding niches (faunivory and folivory). Secondly, we illustrate how stable isotopic variations within African ape populations compare to other extant and extinct primates and discuss possible implications for dietary flexibility. Using 701 carbon and nitrogen isotope data points resulting from 148 sectioned hair samples and an additional collection of 189 fruit samples, we compare six different great ape sites. We investigate the relationship between vegetation baselines and climatic variables, and subsequently correct great ape isotope data to a standardized plant baseline from the respective sites. We obtained temporal isotopic profiles of individual animals by sectioning hair along its growth trajectory. Isotopic signatures of great apes differed between sites, mainly as vegetation isotope baselines were correlated with site-specific climatic conditions. We show that controlling for plant isotopic characteristics at a given site is essential for faunal data interpretation. While accounting for plant baseline effects, we found distinct isotopic profiles for each great ape population. Based on evidence from habituated groups and sympatric great ape species, these differences could possibly be related to faunivory and folivory. Dietary flexibility in apes varied, but temporal variation was overall

  16. Unusual mercury isotopic compositions in aqueous environment

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hintelmann, H.; Zheng, W.; Feng, X.; Cai, H.; Wang, Z.; Yuan, S.

    2014-12-01

    Preliminary studies have demonstrated both mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) of Hg isotopes in natural samples. Laboratory experiments showed that photochemical reduction of inorganic mercury (iHg) and methylmercury (MMHg) and liquid-vapour evaporation could produce MIF of odd Hg isotopes. This was thought to cause the MIF actually observed in aquatic organisms. Although isotopic measurements of Hg in aqueous environment would give direct evidence, little data was reported for surface water samples. Recent work reported, unexpectedly, positive MIF of odd Hg isotopes in both precipitation and ambient air, in contrast with the prediction of laboratory experiments and measurements of Hg accumulated in lichens . Intriguingly, MIF of even-mass Hg isotope (200Hg) was also recently determined in the atmosphere. In contrast with the now mainstream observation of odd Hg isotope anomaly that has several theoretical explanations, the hitherto mysterious even Hg isotope anomalies were neither reported in laboratory experiments, nor predicted by isotope fractionation mechanisms, highlighting the importance of further study on Hg isotopes in variable systems. Our measurements of lichens and lake water samples from different countries show for the first time significant Δ200Hg in surface terrestrial reservoirs, realizing a direct connection of even Hg isotope anomaly in the terrestrial reservoirs to the atmospheric deposition, and fulfilling the gap of Δ200Hg between the atmosphere and the terrestrial receptors. The specific odd Hg isotope compositions determined in lake waters also support the atmosphere contribution, and may be directly linked to the high Δ199Hg values largely determined and manifested on the top of aqueous food web. Our data show that the watershed Hg input is another contributing source, rather than the in-lake processes, to explain the lacustrine Hg isotope anomalies. Interestingly, lake sediments are isotopically

  17. Large Isotope Spectrometer for Astromag

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Klarmann, J.; Israel, M. H.; Garrard, T. L.; Mewaldt, R. A.; Stone, E. C.; Ormes, J. F.; Streitmatter, R. E.; Rasmussen, I. L.; Wiedenbeck, M. E.

    1990-01-01

    The Large Isotope Spectrometer for Astromag (LISA) is an experiment designed to measure the isotopic composition and energy spectra of cosmic rays for elements extending from beryllium through zinc. The overall objectives of this investigation are to study the origin and evolution of galactic matter; the acceleration, transport, and time scales of cosmic rays in the galaxy; and search for heavy antinuclei in the cosmic radiation. To achieve these objectives, the LISA experiment will make the first identifications of individual heavy cosmic ray isotopes in the energy range from about 2.5 to 4 GeV/n where relativistic time dilation effects enhance the abundances of radioactive clocks and where the effects of solar modulation and cross-section variations are minimized. It will extend high resolution measurements of individual element abundances and their energy spectra to energies of nearly 1 TeV/n, and has the potential for discovering heavy anti-nuclei which could not have been formed except in extragalactic sources.

  18. Isotope Fractionation During Microbial Metal Assimilation

    NASA Astrophysics Data System (ADS)

    Anbar, A.; Wasylenki, L.; Liermann, L.; Mathur, R.; Brantley, S.

    2006-12-01

    The possibility that metal stable isotopes record the influence of microbes on metal geochemical cycling has motivated much recent research on "non-traditional" stable isotopes, particularly Fe. The initial wave of research on biogenic metal isotope effects focused on Fe isotope fractionation during microbially-mediated dissimilatory reduction or oxidation of Fe. Although isotope variations arising from biogenic effects have been reported in laboratory systems it is difficult to ascribe comparable variations in nature to biology because of pervasive and significant abiotic fractionation. As an alternative approach, we are investigating isotope fractionation during microbial assimilation of transition metals. Assimilation occurs because a large number of metals are essential intracellular constituents. Although assimilatory isotope fractionation is not likely to be unique in direction or magnitude compared to other processes, the large number of elements potentially involved greatly broadens the number of elements that can be examined for biogenic isotope effects in materials of interest. This raises the possibility of multi- element isotope "fingerprints" of biological metal processing. In experiments with Azotobacter vinelandii, a nitrogen-fixing soil bacterium that does not use Fe or other metals in dissimilatory respiration, fractionation of both Fe and Mo isotopes are observed. The two systems exhibit opposite sense fractionation: preferential assimilation of heavy isotopes is observed for Fe, while Mo assimilation favors uptake of light isotopes. Rayleigh-type behavior is seen in both cases; α = 1.0011 and 0.9997, respectively. The Fe isotope results are most readily interpreted in terms of an equilibrium fractionation between inorganic Fe complexes and strongly bound Fe-siderophore complexes that are taken into the cell. In contrast, the Mo isotope results may reflect a kinetic isotope effect. However, it is alternatively possible that Mo isotope

  19. A novel methodology to investigate isotopic biosignatures

    NASA Astrophysics Data System (ADS)

    Horner, T. J.; Lee, R. B. Y.; Henderson, G. M.; Rickaby, R. E. M.

    2012-04-01

    An enduring goal of trace metal isotopic studies of Earth History is to find isotopic 'fingerprints' of life or of life's individual physiochemical processes. Generally, such signatures are sought by relating an isotopic effect observed in controlled laboratory conditions or a well-characterized environment to a more complex system or the geological record. However, such an approach is ultimately limited because life exerts numerous isotopic fractionations on any one element so it is hard to dissect the resultant net fractionation into its individual components. Further, different organisms, often with the same apparent cellular function, can express different isotopic fractionation factors. We have used a novel method to investigate the isotopic fractionation associated with a single physiological process-enzyme specific isotopic fractionation. We selected Cd isotopes since only one biological use of Cd is known, CdCA (a Cd/Zn carbonic anhydrase from the coastal diatom T. Weissflogii). Thus, our investigation can also inform the long standing mystery as to why this generally toxic element appears to have a nutrient-like dissolved isotopic and concentration profile in the oceans. We used the pET-15b plasmid to insert the CdCA gene into the E. coli genome. There is no known biochemical function for Cd in E. coli, making it an ideal vector for studying distinct physiological processes within a single organism. The uptake of Cd and associated isotopic fractionation was determined for both normal cells and those expressing CdCA. It was found that whole cells always exhibited a preference for the light isotopes of Cd, regardless of the expression of CdCA; adsorption of Cd to cell surfaces was not seen to cause isotopic fractionation. However, the cleaning procedure employed exerted a strong control on the observed isotopic composition of cells. Using existing protein purification techniques, we measured the Cd isotopic composition of different subcellular fractions of E

  20. Deformation properties of lead isotopes

    SciTech Connect

    Tolokonnikov, S. V.; Borzov, I. N.; Lutostansky, Yu. S.; Saperstein, E. E.

    2016-01-15

    The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF{sup 0} Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, {sup 180}Pb and {sup 184}Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF{sup 0} functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF{sup 0} functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron

  1. Stable Isotope Enrichment Capabilities at ORNL

    SciTech Connect

    Egle, Brian; Aaron, W Scott; Hart, Kevin J

    2013-01-01

    The Oak Ridge National Laboratory (ORNL) and the US Department of Energy Nuclear Physics Program have built a high-resolution Electromagnetic Isotope Separator (EMIS) as a prototype for reestablishing a US based enrichment capability for stable isotopes. ORNL has over 60 years of experience providing enriched stable isotopes and related technical services to the international accelerator target community, as well as medical, research, industrial, national security, and other communities. ORNL is investigating the combined use of electromagnetic and gas centrifuge isotope separation technologies to provide research quantities (milligram to several kilograms) of enriched stable isotopes. In preparation for implementing a larger scale production facility, a 10 mA high-resolution EMIS prototype has been built and tested. Initial testing of the device has simultaneously collected greater than 98% enriched samples of all the molybdenum isotopes from natural abundance feedstock.

  2. Possible isotopic fractionation effects in sputtered minerals

    NASA Technical Reports Server (NTRS)

    Haff, P. K.; Watson, C. C.; Tombrello, T. A.

    1980-01-01

    A model which makes definite predictions for the fractionation of isotopes in sputtered material is discussed. The fractionation patterns are nonlinear, and the pattern for a particular set of isotopes depends on the chemical matrix within which those isotopes are contained. Calculations are presented for all nonmonoisotopic elements contained in the minerals perovskite, anorthite, ackermanite, enstatite, and troilite. All isotopes are fractionated at the level of approximately 4-6 deg/o per atomic mass unit. Oxygen is always positively fractionated (heavier isotopes sputtered preferentially), and heavier elements are generally negatively fractioned (light isotopes sputtered preferentially). The value of Delta (O-18:O-16) is always less by about 1.8 deg/o than a linear extrapolation based upon the calculated delta (O-17:O-16) value would suggest. The phenomenon of both negative and positive fractionation patterns from a single target mineral are used to make an experimental test of the proposed model.

  3. Isotope Geochemistry for Comparative Planetology of Exoplanets

    NASA Technical Reports Server (NTRS)

    Mandt, K. E.; Atreya, S.; Luspay-Kuti, A.; Mousis, O.; Simon, A.; Hofstadter, M. D.

    2017-01-01

    Isotope geochemistry has played a critical role in understanding processes at work in and the history of solar system bodies. Application of these techniques to exoplanets would be revolutionary and would allow comparative planetology with the formation and evolution of exoplanet systems. The roadmap for comparative planetology of the origins and workings of exoplanets involves isotopic geochemistry efforts in three areas: (1) technology development to expand observations of the isotopic composition of solar system bodies and expand observations to isotopic composition of exoplanet atmospheres; (2) theoretical modeling of how isotopes fractionate and the role they play in evolution of exoplanetary systems, atmospheres, surfaces and interiors; and (3) laboratory studies to constrain isotopic fractionation due to processes at work throughout the solar system.

  4. Calcium and titanium isotopic fractionations during evaporation

    NASA Astrophysics Data System (ADS)

    Zhang, Junjun; Huang, Shichun; Davis, Andrew M.; Dauphas, Nicolas; Hashimoto, Akihiko; Jacobsen, Stein B.

    2014-09-01

    Isotope fractionations associated with high temperature evaporation provide important constraints on the physicochemical processes that affected planetary materials at the birth of the solar system. Previous evaporation experiments have focused on isotopic fractionation of moderately to highly volatile elements. Here, we investigate the isotope fractionation behavior of two highly refractory elements, calcium and titanium, during evaporation of perovskite (CaTiO3) in a vacuum furnace. In our experiments, isotope fractionation during evaporation follows the Rayleigh law, but not the commonly used exponential law, with the dominant evaporating species being Ca(g) and TiO2(g). If isotope fractionations in early solar system materials did follow the Rayleigh law, the common practice of using an exponential fractionation law to correct for mass-dependent fractionation in the study of mass-independent fractionations may introduce significant artificial isotope anomalies.

  5. Stable Isotope Signatures for Microbial Forensics

    SciTech Connect

    Kreuzer, Helen W.

    2012-01-03

    The isotopic distribution of the atoms composing the molecules of microorganisms is a function of the substrates used by the organisms. The stable isotope content of an organism is fixed so long as no further substrate consumption and biosynthesis occurs, while the radioactive isotopic content decays over time. The distribution of stable isotopes of C, N, O and H in heterotrophic microorganisms is a direct function of the culture medium, and therefore the stable isotope composition can be used to associate samples with potential culture media and also with one another. The 14C content depends upon the 14C content, and therefore the age, of the organic components of the culture medium, as well as on the age of the culture itself. Stable isotope signatures can thus be used for sample matching, to associate cultures with specific growth media, and to predict characteristics of growth media.

  6. Isotope exchange in oxide-containing catalyst

    NASA Technical Reports Server (NTRS)

    Brown, Kenneth G. (Inventor); Upchurch, Billy T. (Inventor); Hess, Robert V. (Inventor); Miller, Irvin M. (Inventor); Schryer, David R. (Inventor); Sidney, Barry D. (Inventor); Wood, George M. (Inventor); Hoyt, Ronald F. (Inventor)

    1989-01-01

    A method of exchanging rare-isotope oxygen for common-isotope oxygen in the top several layers of an oxide-containing catalyst is disclosed. A sample of an oxide-containing catalyst is exposed to a flowing stream of reducing gas in an inert carrier gas at a temperature suitable for the removal of the reactive common-isotope oxygen atoms from the surface layer or layers of the catalyst without damaging the catalyst structure. The reduction temperature must be higher than any at which the catalyst will subsequently operate. Sufficient reducing gas is used to allow removal of all the reactive common-isotope oxygen atoms in the top several layers of the catalyst. The catalyst is then reoxidized with the desired rare-isotope oxygen in sufficient quantity to replace all of the common-isotope oxygen that was removed.

  7. Isoscapes: Spatial Pattern in Isotopic Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Bowen, Gabriel J.

    2010-05-01

    Isotope ratios of actively cycled elements vary as a function of the biogeochemical processes in which they participate and the conditions under which those processes occur. The resultant spatiotemporal distribution of isotopes in environmental materials can be predicted using models of isotope-fractionating processes and data describing environmental conditions across space and time, and it has been termed an isoscape, or isotopic landscape. Analysis of isoscapes and comparison of isoscape predictions with observational data have been used to test biogeochemical models, calculate aerially integrated biogeochemical fluxes based on isotope mass balance, and determine spatial connectivity in biogeochemical, ecological, and anthropological systems. Isoscape models of varying quality are available for stable H, C, N, and O isotopes in a range of Earth surface systems, but significant opportunities exist to refine our understanding of biogeochemical cycles and our ability to predict isoscapes through the development of more mechanistic and more comprehensive isoscape models.

  8. Measuring In Vivo Ureagenesis With Stable Isotopes

    PubMed Central

    Yudkoff, Marc; Mew, Nicholas Ah; Daikhin, Yevgeny; Horyn, Oksana; Nissim, Ilana; Nissim, Itzhak; Payan, Irma; Tuchman, Mendel

    2010-01-01

    Stable isotopes have been an invaluable adjunct to biomedical research for more than 70 years. Indeed, the isotopic approach has revolutionized our understanding of metabolism, revealing it to be an intensely dynamic process characterized by an unending cycle of synthesis and degradation. Isotopic studies have taught us that the urea cycle is intrinsic to such dynamism, since it affords a capacious mechanism by which to eliminate waste nitrogen when rates of protein degradation (or dietary protein intake) are especially high. Isotopes have enabled an appreciation of the degree to which ureagenesis is compromised in patients with urea cycle defects. Indeed, isotopic studies of urea cycle flux correlate well with the severity of cognitive impairment in these patients. Finally, the use of isotopes affords an ideal tool with which to gauge the efficacy of therapeutic interventions to augment residual flux through the cycle. PMID:20338795

  9. Chemical production of chondrule oxygen isotopic composition

    NASA Technical Reports Server (NTRS)

    Thiemens, M. H.

    1994-01-01

    Defining the source of observed meteoritic O isotopic anomalies remains a fundamental challenge. The O isotopic composition of chondrules are particularly striking. There are at least three types of chemical processes that produce the isotopic compositions observed in chondrules and Ca-Al-rich inclusions (CAI's). The processes are rather general, viz, they require no specialized processes and the processes associated with chondrule production are likely to produce the observed compositions.

  10. Multiple linear regression for isotopic measurements

    NASA Astrophysics Data System (ADS)

    Garcia Alonso, J. I.

    2012-04-01

    There are two typical applications of isotopic measurements: the detection of natural variations in isotopic systems and the detection man-made variations using enriched isotopes as indicators. For both type of measurements accurate and precise isotope ratio measurements are required. For the so-called non-traditional stable isotopes, multicollector ICP-MS instruments are usually applied. In many cases, chemical separation procedures are required before accurate isotope measurements can be performed. The off-line separation of Rb and Sr or Nd and Sm is the classical procedure employed to eliminate isobaric interferences before multicollector ICP-MS measurement of Sr and Nd isotope ratios. Also, this procedure allows matrix separation for precise and accurate Sr and Nd isotope ratios to be obtained. In our laboratory we have evaluated the separation of Rb-Sr and Nd-Sm isobars by liquid chromatography and on-line multicollector ICP-MS detection. The combination of this chromatographic procedure with multiple linear regression of the raw chromatographic data resulted in Sr and Nd isotope ratios with precisions and accuracies typical of off-line sample preparation procedures. On the other hand, methods for the labelling of individual organisms (such as a given plant, fish or animal) are required for population studies. We have developed a dual isotope labelling procedure which can be unique for a given individual, can be inherited in living organisms and it is stable. The detection of the isotopic signature is based also on multiple linear regression. The labelling of fish and its detection in otoliths by Laser Ablation ICP-MS will be discussed using trout and salmon as examples. As a conclusion, isotope measurement procedures based on multiple linear regression can be a viable alternative in multicollector ICP-MS measurements.

  11. Quantitative Microbial Ecology through Stable Isotope Probing

    PubMed Central

    Mau, Rebecca L.; Schwartz, Egbert; Caporaso, J. Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J.; Liu, Cindy M.; McHugh, Theresa A.; Marks, Jane C.; Morrissey, Ember M.; Price, Lance B.

    2015-01-01

    Bacteria grow and transform elements at different rates, and as yet, quantifying this variation in the environment is difficult. Determining isotope enrichment with fine taxonomic resolution after exposure to isotope tracers could help, but there are few suitable techniques. We propose a modification to stable isotope probing (SIP) that enables the isotopic composition of DNA from individual bacterial taxa after exposure to isotope tracers to be determined. In our modification, after isopycnic centrifugation, DNA is collected in multiple density fractions, and each fraction is sequenced separately. Taxon-specific density curves are produced for labeled and nonlabeled treatments, from which the shift in density for each individual taxon in response to isotope labeling is calculated. Expressing each taxon's density shift relative to that taxon's density measured without isotope enrichment accounts for the influence of nucleic acid composition on density and isolates the influence of isotope tracer assimilation. The shift in density translates quantitatively to isotopic enrichment. Because this revision to SIP allows quantitative measurements of isotope enrichment, we propose to call it quantitative stable isotope probing (qSIP). We demonstrated qSIP using soil incubations, in which soil bacteria exhibited strong taxonomic variations in 18O and 13C composition after exposure to [18O]water or [13C]glucose. The addition of glucose increased the assimilation of 18O into DNA from [18O]water. However, the increase in 18O assimilation was greater than expected based on utilization of glucose-derived carbon alone, because the addition of glucose indirectly stimulated bacteria to utilize other substrates for growth. This example illustrates the benefit of a quantitative approach to stable isotope probing. PMID:26296731

  12. METHOD AND APPARATUS FOR COLLECTING ISOTOPES

    DOEpatents

    Leyshon, W.E.

    1957-08-01

    A method and apparatus for collecting isotopes having a high vapor pressure, such as isotopes of mercury, in a calutron are described. Heretofore, the collected material would vaporize and escape from the ion receiver as fast as it was received. By making the receiver of pure silver, the mercury isotopes form a nonvolatile amalgam with the silver at the water cooled temperature of the receiver, and the mercury is thus retained.

  13. Method for isotope separation by photodeflection

    DOEpatents

    Bernhardt, Anthony F.

    1977-01-01

    In the method of separating isotopes wherein a desired isotope species is selectively deflected out of a beam of mixed isotopes by irradiating the beam with a directed beam of light of narrowly defined frequency which is selectively absorbed by the desired species, the improvement comprising irradiating the deflected beam with light from other light sources whose frequencies are selected to cause the depopulation of any metastable excited states.

  14. Review of the magnetic isotope method for isotopic separation and enrichment

    SciTech Connect

    Turro, N.J.

    1985-01-01

    In the Progress Report of November 19, 1985 a detailed review of the theory of the magnetic isotope method for isotope separation and enrichment was presented. Here we present only the major qualitative features of the theory of the magnetic isotope effect, and we indicate how these aspects can be exploited to design experiments which demonstrate the feasibility and practicability of the magnetic isotope method.

  15. Carbon isotopic composition of Amazon shelf sediments

    SciTech Connect

    Showers, W.J.; Angle, D.G.; Nittrouer, C.A.; Demaster, D.J.

    1985-02-01

    The distribution of carbon isotopes in Amazon shelf sediment is controlled by the same processes that are forming the modern subaqueous delta. The terrestrial (-27 to -25 per thousand) isotopic carbon signal observed in surficial sediments near the river mouth extends over 400 km northwest along the shelf. Terrestrial carbon is associated with areas of rapid sediment accumulation (topset and foreset regions). A sharp boundary between terrestrial (-27 to -25 per thousand) and marine (-23 to -22 per thousand) isotopic carbon values in surficial sediments is associated with a change in depositional conditions (foreset to bottomset regions) and a decrease in sediment accumulation rate. POC water-column isotopic values (-27 per thousand) near the river mouth are similar to the underlying surficial-sediment TOC isotopic values, but POC water-column samples collected 20 km off the river mouth have marine carbon isotopic values (-22 to -19 per thousand) and differ from the underlying surficial-sediment TOC isotopic values. These water column observations are related to variations in turbidity and productivity. Down-core isotopic variation is only observed in cores taken in areas of lower sediment accumulation rates. These observations indicate that the organic carbon in Amazon shelf sediment is dominantly terrestrial in composition, and the location of deposition of this carbon is controlled by modern processes of sediment accumulation. The modern Amazon shelf is similar to large clinoform shale deposits of the Cretaceous in North America. Thus, the stratigraphic setting may help predict the isotopic variations of carbon in ancient deposits.

  16. THEORETICAL AND EXPERIMENTAL ASPECTS OF ISOTOPIC FRACTIONATION.

    USGS Publications Warehouse

    O'Neil, James R.

    1986-01-01

    Essential to the interpretation of natural variations of light stable isotope ratios is knowledge of the magnitude and temperature dependence of isotopic fractionation factors between the common minerals and fluids. These fractionation factors are obtained in three ways: (1) Semi-empirical calculations using spectroscopic data and the methods of statistical mechanics. (2) Laboratory calibration studies. (3) Measurements of natural samples whose formation conditions are well-known or highly constrained. In this chapter methods (1) and (2) are evaluated and a review is given of the present state of knowledge of the theory of isotopic fractionation and the fraction that influence the isotopic properties of minerals.

  17. Method for isotope enrichment by photoinduced chemiionization

    DOEpatents

    Dubrin, James W.

    1985-01-01

    Isotope enrichment, particularly .sup.235 U enrichment, is achieved by irradiating an isotopically mixed vapor feed with radiant energy at a wavelength or wavelengths chosen to selectively excite the species containing a desired isotope to a predetermined energy level. The vapor feed if simultaneously reacted with an atomic or molecular reactant species capable of preferentially transforming the excited species into an ionic product by a chemiionization reaction. The ionic product, enriched in the desired isotope, is electrostatically or electromagnetically extracted from the reaction system.

  18. Stable isotope labeling methods for DNA.

    PubMed

    Nelissen, Frank H T; Tessari, Marco; Wijmenga, Sybren S; Heus, Hans A

    2016-08-01

    NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Atom trap trace analysis of krypton isotopes

    SciTech Connect

    Bailey, K.; Chen, C. Y.; Du, X.; Li, Y. M.; Lu, Z.-T.; O'Connor, T. P.; Young, L.

    1999-11-17

    A new method of ultrasensitive isotope trace analysis has been developed. This method, based on the technique of laser manipulation of neutral atoms, has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton gas sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. This method is free of contamination from other isotopes and elements and can be applied to several different isotope tracers for a wide range of applications. The demonstrated detection efficiency is 1 x 10{sup {minus}7}. System improvements could increase the efficiency by many orders of magnitude.

  20. Adsorption and isotopic fractionation of Xe

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.

    1986-01-01

    A theoretical description of the mechanisms of isotopic fractionation arising during adsorption of noble gases in a Henry's Law pressure regime is given. Experimental data on the isotopic composition of Xe adsorbed on activated charcoal in the temperature range 220 K to 350 K are presented. Both theoretical considerations and the experimental data indicate that equilibrium adsorption does not significantly alter the isotopic structure of adsorbed structure of adsorbed noble gases. Therefore, if adsorption is responsible for the elemental noble gas pattern in meteorites and the earth, the heavy noble gas isotopic fractionation between them must have been produced prior to and by a different process than equilibrium adsorption.

  1. Adsorption and isotopic fractionation of Xe

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.

    1986-01-01

    A theoretical description of the mechanisms of isotopic fractionation arising during adsorption of noble gases in a Henry's Law pressure regime is given. Experimental data on the isotopic composition of Xe adsorbed on activated charcoal in the temperature range 220 K to 350 K are presented. Both theoretical considerations and the experimental data indicate that equilibrium adsorption does not significantly alter the isotopic structure of adsorbed structure of adsorbed noble gases. Therefore, if adsorption is responsible for the elemental noble gas pattern in meteorites and the earth, the heavy noble gas isotopic fractionation between them must have been produced prior to and by a different process than equilibrium adsorption.

  2. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Winschel, R.A.; Lancet, M.S.; Burke, F.P.

    1991-04-01

    This is the final report which was a thirty-four month project conducted to develop and demonstrate stable carbon isotope analysis as a method to quantitatively distinguish the source of carbon in products of coal/petroleum coprocessing. The work included assessing precision, accuracy, the range of application and the significance of selective isotopic fractionation effects. A method was devised to correct for selective isotopic fractionation errors. The method was demonstrated through application with samples from twelve continuous-unit coprocessing tests. A data base of carbon isotope analyses is appended. 21 refs.

  3. Oxygen isotopes in deep-sea spherules

    NASA Technical Reports Server (NTRS)

    Clayton, Robert N.; Mayeda, Toshiko K.; Brownlee, Donald E.

    1986-01-01

    Oxygen isotopic compositions have been measured on several size fractions of deep-sea spherules of extraterrestrial origin. The silicate spherules have an isotopic composition unlike that of any known macrometeorite. Their pre-terrestrial compositions may have been similar to those of C3 chondrites or the anhydrous component of C2 chondrites, the latter being preferred on chemical grounds. Metallic particles oxidize in the upper atmosphere, and sample a region for which no previous oxygen isotope data exist. This part of the atmosphere, above about 100 km, is apparently strongly enriched in the heavy isotopes of oxygen.

  4. Physics of a Rare Isotope Accelerator

    NASA Astrophysics Data System (ADS)

    Geesaman, D. F.; Gelbke, C. K.; Janssens, R. V. F.; Sherrill, B. M.

    2006-11-01

    Major progress in nuclear research and in observations of the cosmos has made it clear that critical issues in understanding the nucleus and astrophysical processes require abundant new sources of exotic nuclei, away from the realm of the stable ones. Recent advances in accelerator and isotope-production technology make access to these rare isotopes possible. This review examines the impact of the new reach in physics provided by a rare isotope accelerator in nuclear structure, astrophysics, and searches for physics beyond the standard model. We also touch briefly on some of the benefits of these isotopes for other important societal needs.

  5. Uranium isotopes fingerprint biotic reduction

    SciTech Connect

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J.; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-04-20

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. In addition, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.

  6. Uranium isotopes fingerprint biotic reduction

    DOE PAGES

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; ...

    2015-04-20

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U),more » i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. In addition, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.« less

  7. Uranium isotopes fingerprint biotic reduction

    PubMed Central

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J.; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-01-01

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. Additionally, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium. PMID:25902522

  8. Uranium isotopes fingerprint biotic reduction.

    PubMed

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-05-05

    Knowledge of paleo-redox conditions in the Earth's history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth's crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. Additionally, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.

  9. Hydrogen-isotope permeation barrier

    DOEpatents

    Maroni, Victor A.; Van Deventer, Erven H.

    1977-01-01

    A composite including a plurality of metal layers has a Cu-Al-Fe bronze layer and at least one outer layer of a heat and corrosion resistant metal alloy. The bronze layer is ordinarily intermediate two outer layers of metal such as austenitic stainless steel, nickel alloys or alloys of the refractory metals. The composite provides a barrier to hydrogen isotopes, particularly tritium that can reduce permeation by at least about 30 fold and possibly more below permeation through equal thicknesses of the outer layer material.

  10. Osmium isotopes and mantle convection.

    PubMed

    Hauri, Erik H

    2002-11-15

    The decay of (187)Re to (187)Os (with a half-life of 42 billion years) provides a unique isotopic fingerprint for tracing the evolution of crustal materials and mantle residues in the convecting mantle. Ancient subcontinental mantle lithosphere has uniquely low Re/Os and (187)Os/(188)Os ratios due to large-degree melt extraction, recording ancient melt-depletion events as old as 3.2 billion years. Partial melts have Re/Os ratios that are orders of magnitude higher than their sources, and the subduction of oceanic or continental crust introduces into the mantle materials that rapidly accumulate radiogenic (187)Os. Eclogites from the subcontinental lithosphere have extremely high (187)Os/(188)Os ratios, and record ages as old as the oldest peridotites. The data show a near-perfect partitioning of Re/Os and (187)Os/(188)Os ratios between peridotites (low) and eclogites (high). The convecting mantle retains a degree of Os-isotopic heterogeneity similar to the lithospheric mantle, although its amplitude is modulated by convective mixing. Abyssal peridotites from the ocean ridges have low Os isotope ratios, indicating that the upper mantle had undergone episodes of melt depletion prior to the most recent melting events to produce mid-ocean-ridge basalt. The amount of rhenium estimated to be depleted from the upper mantle is 10 times greater than the rhenium budget of the continental crust, requiring a separate reservoir to close the mass balance. A reservoir consisting of 5-10% of the mantle with a rhenium concentration similar to mid-ocean-ridge basalt would balance the rhenium depletion of the upper mantle. This reservoir most likely consists of mafic oceanic crust recycled into the mantle over Earth's history and provides the material that melts at oceanic hotspots to produce ocean-island basalts (OIBs). The ubiquity of high Os isotope ratios in OIB, coupled with other geochemical tracers, indicates that the mantle sources of hotspots contain significant quantities

  11. Coordination Modes of Americium in the Am2(C2O4)3(H2O)6·4H2O Oxalate: Synthesis, Crystal Structure, Spectroscopic Characterizations and Comparison in the M2(C2O4)3(H2O)6·nH2O (M = Ln, An) Series.

    PubMed

    Tamain, C; Arab-Chapelet, B; Rivenet, M; Legoff, X F; Loubert, G; Grandjean, S; Abraham, F

    2016-01-04

    Americium oxalate single crystals, Am2(C2O4)3(H2O)6·4H2O, were prepared by in situ oxalic acid generation by slow hydrolysis of the diester. Their structure was determined by single-crystal X-ray diffraction and was solved by the direct methods and Fourier difference techniques. The structure (space group P21/c, a = 11.184(4) Å, b = 9.489(4) Å, c = 10.234(4) Å, β = 114.308(8)°, Z = 2) consists of layers formed by six-membered rings of actinide metals connected through oxalate ions. The americium atoms are nine-coordinated by six oxygen atoms from three bidentate oxalate ligands and three water molecules. The distances within the coordination sphere as well as infrared and Raman spectra of several isostructural lanthanide (Ce(III), Pr(III), Nd(III), Sm(III), Gd(III)) and actinide (Pu(III), Am(III)) oxalates were compared to evaluate the similarities and the differences between the two series.

  12. New isotope {sup 263}Hs

    SciTech Connect

    Dragojevic, I.; Ellison, P. A.; Gates, J. M.; Nelson, S. L.; Nitsche, H.; Gregorich, K. E.; Dvorak, J.; Stavsetra, L.; Duellmann, Ch. E.

    2009-01-15

    A new isotope of Hs was produced in the reaction {sup 208}Pb({sup 56}Fe,n){sup 263}Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope {sup 263}Hs. The measured cross section was 21{sub -8.4}{sup +13} pb at 276.4 MeV lab frame center-of-target beam energy. {sup 263}Hs decays with a half-life of 0.74{sub -0.21}{sup +0.48} ms by {alpha}-decay and the measured {alpha}-particle energies are 10.57 {+-} 0.06, 10.72 {+-} 0.06, and 10.89 {+-} 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. SwiaPtecki et al., Phys. Rev. C 71, 014602 (2005)].

  13. Magnesium isotope geochemistry in arc volcanism.

    PubMed

    Teng, Fang-Zhen; Hu, Yan; Chauvel, Catherine

    2016-06-28

    Incorporation of subducted slab in arc volcanism plays an important role in producing the geochemical and isotopic variations in arc lavas. The mechanism and process by which the slab materials are incorporated, however, are still uncertain. Here, we report, to our knowledge, the first set of Mg isotopic data for a suite of arc lava samples from Martinique Island in the Lesser Antilles arc, which displays one of the most extreme geochemical and isotopic ranges, although the origin of this variability is still highly debated. We find the δ(26)Mg of the Martinique Island lavas varies from -0.25 to -0.10, in contrast to the narrow range that characterizes the mantle (-0.25 ± 0.04, 2 SD). These high δ(26)Mg values suggest the incorporation of isotopically heavy Mg from the subducted slab. The large contrast in MgO content between peridotite, basalt, and sediment makes direct mixing between sediment and peridotite, or assimilation by arc crust sediment, unlikely to be the main mechanism to modify Mg isotopes. Instead, the heavy Mg isotopic signature of the Martinique arc lavas requires that the overall composition of the mantle wedge is buffered and modified by the preferential addition of heavy Mg isotopes from fluids released from the altered subducted slab during fluid-mantle interaction. This, in turn, suggests transfer of a large amount of fluid-mobile elements from the subducting slab to the mantle wedge and makes Mg isotopes an excellent tracer of deep fluid migration.

  14. Uses of stable isotopes in fish ecology

    EPA Science Inventory

    Analyses of fish tissues (other than otoliths) for stable isotope ratios can provide substantial information on fish ecology, including physiological ecology. Stable isotopes of nitrogen and carbon frequently are used to determine the mix of diet sources for consumers. Stable i...

  15. Uses of stable isotopes in fish ecology

    EPA Science Inventory

    Analyses of fish tissues (other than otoliths) for stable isotope ratios can provide substantial information on fish ecology, including physiological ecology. Stable isotopes of nitrogen and carbon frequently are used to determine the mix of diet sources for consumers. Stable i...

  16. Isotope effect of mercury diffusion in air

    PubMed Central

    Koster van Groos, Paul G.; Esser, Bradley K.; Williams, Ross W.; Hunt, James R.

    2014-01-01

    Identifying and reducing impacts from mercury sources in the environment remains a considerable challenge and requires process based models to quantify mercury stocks and flows. The stable isotope composition of mercury in environmental samples can help address this challenge by serving as a tracer of specific sources and processes. Mercury isotope variations are small and result only from isotope fractionation during transport, equilibrium, and transformation processes. Because these processes occur in both industrial and environmental settings, knowledge of their associated isotope effects is required to interpret mercury isotope data. To improve the mechanistic modeling of mercury isotope effects during gas phase diffusion, an experimental program tested the applicability of kinetic gas theory. Gas-phase elemental mercury diffusion through small bore needles from finite sources demonstrated mass dependent diffusivities leading to isotope fractionation described by a Rayleigh distillation model. The measured relative atomic diffusivities among mercury isotopes in air are large and in agreement with kinetic gas theory. Mercury diffusion in air offers a reasonable explanation of recent field results reported in the literature. PMID:24364380

  17. Isotope Program Report June FY2016

    SciTech Connect

    Lewis, Jr, Benjamin E.; Egle, Brian

    2016-09-01

    Isotope Program Monthly Highlights are briefly described. These include data on isotopes shipped, updates on equipment fabrication and testing, a potential new approach for nondestructive measurement of the amount of Cf-252 deposited on a surface, and efforts to recover and purify uranium-234 obtained from old PuBe sources.

  18. Isotopic equilibrium between shells and their environement.

    PubMed

    Mook, W G; Vogel, J C

    1968-02-23

    The carbon-isotopic composition of shell carbonate is shown to be in isotopic equilibrium with bicarbonate dissolved in the water. By measurement of both 13C and 18O in a series of brackish-water shells a mean growth temperature can be deduced.

  19. Xenon Isotope Releases from Buried Transuranic Waste

    NASA Astrophysics Data System (ADS)

    Dresel, P. E.; Waichler, S. R.; Kennedy, B. M.; Hayes, J. C.; McIntyre, J. I.; Giles, J. R.; Sondrup, A. J.

    2004-12-01

    Xenon is an inert rare gas produced as a fission product in nuclear reactors and through spontaneous fission of some transuranic isotopes. Thus, xenon will be released from buried transuranic waste. Two complementary methods are used to measure xenon isotopes: radiometric analysis for short-lived radioxenon isotopes and mass spectrometry for detection of stable xenon isotopes. Initial measurements near disposal facilities at the U.S. Department of Energy's Hanford Site show radioxenon and stable xenon isotopic signatures that are indicative of transuranic waste. Radioxenon analysis has greater sensitivity due to the lower background concentrations and indicates spontaneous fission due to the short half life of the isotopes. Stable isotope ratios may be used to distinguish irradiated fuel sources from pure spontaneous fission sources and are not as dependent on rapid release from the waste form. The release rate is dependent on the type of waste and container integrity and is the greatest unknown in application of this technique. Numerical multi-phase transport modeling of burial grounds at the Idaho National Engineering and Environmental Laboratory indicates that, under generalized conditions, the radioxenon isotopes will diffuse away from the waste and be found in the soil cap and adjacent to the burial ground at levels many orders of magnitude above the detection limit.

  20. Isotope separation by selective photodissociation of glyoxal

    DOEpatents

    Marling, John B.

    1976-01-01

    Dissociation products, mainly formaldehyde and carbon monoxide, enriched in a desired isotope of carbon, oxygen, or hydrogen are obtained by the selective photodissociation of glyoxal wherein glyoxal is subjected to electromagnetic radiation of a predetermined wavelength such that photon absorption excites and induces dissociation of only those molecules of glyoxal containing the desired isotope.