WorldWideScience

Sample records for americium selenides

  1. Formation of copper-indium-selenide and/or copper-indium-gallium-selenide films from indium selenide and copper selenide precursors

    Science.gov (United States)

    Curtis, Calvin J.; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S.; Nekuda, Jennifer A.

    2011-11-15

    Liquid-based indium selenide and copper selenide precursors, including copper-organoselenides, particulate copper selenide suspensions, copper selenide ethylene diamine in liquid solvent, nanoparticulate indium selenide suspensions, and indium selenide ethylene diamine coordination compounds in solvent, are used to form crystalline copper-indium-selenide, and/or copper indium gallium selenide films (66) on substrates (52).

  2. Preparation of americium amalgam

    International Nuclear Information System (INIS)

    The authors describe a method for the electrochemical preparation of an americium amalgam from americium dioxide and americium 241 and 243 for use in determining the physicochemical properties of the alloy. Moessbauer spectra were made using neptunium dioxide, in the neptunium 237 form, as an absorber. Results show that electrolysis produces a homogeneous amalgam that gives an unoxidized product on vacuum distillation at 200 degrees C

  3. Americium recovery from reduction residues

    Science.gov (United States)

    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)

  4. Preparation of americium amalgam

    International Nuclear Information System (INIS)

    Using the method of NGR-spectroscopy with the aid of 241Am isotope chemical state of transuranium elements in the volume and on the surface of amalgams is studied. Amalgam preparation was realized in a simplified electrolytic cell. It is shown that in the process of amalgam preparation the first order of reaction as to actinide is observed; americium is distributed gradually over the volume and it is partially sorbed by the surface of glass capillary. NGR spectrum of dry residue after mercury distillation at 200 deg C points to the presence of americium-mercury intermetal compounds

  5. Chemistry of americium

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, W.W.

    1976-01-01

    Essential features of the descriptive chemistry of americium are reviewed. Chapter titles are: discovery, atomic and nuclear properties, collateral reading, production and uses, chemistry in aqueous solution, metal, alloys, and compounds, and, recovery, separation, purification. Author and subject indexes are included. (JCB)

  6. Americium-241 - ED 4308

    International Nuclear Information System (INIS)

    This sheet presents the characteristics of Americium-241, its origin, and its radio-physical and biological properties. It briefly describes its use in nuclear medicine. It indicates its dosimetric parameters for external exposure, cutaneous contamination, and internal exposure due to acute contamination or to chronic contamination. It indicates and comments the various exposure control techniques: ambient dose rate measurement, surface contamination measurement, atmosphere contamination. It addresses the means of protection: premise design, protection against external exposure and against internal exposure. It describes how areas are delimited and controlled within the premises: regulatory areas, controls to be performed. It addresses the personnel classification, training and medical survey. It addresses the issue of wastes and effluents. It briefly recalls the administrative procedures related to the authorization and declaration of possession and use of sealed and unsealed sources. It indicates regulatory aspects related to the road transport of Americium-241, describes what is to be done in case of incident or accident (for the different types of contamination or exposure)

  7. The Biokinetic Model of Americium

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    To improve in vivo measurements for detecting internal exposure from transuranium radio nuclides, such as neptunium, plutonium, americium, the bioknetic model was studied. According to ICRP report (1993, 1995, 1997) and other research, the

  8. Americium product solidification and disposal

    International Nuclear Information System (INIS)

    The americium product from the TRUEX processing plant needs to be converted into a form suitable for ultimate disposal. An evaluation of the disposal based on safety, number of process steps, demonstrated operability of the processes, production of low-level alpha waste streams, and simplicity of maintenance with low radiation exposures to personnel during maintenance, has been made. The best process is to load the americium on a cation exchange resin followed by calcination or oxidation of the resin after loading

  9. Science and Technology for Americium Transmutation

    International Nuclear Information System (INIS)

    Americium could be seen as the most troublesome element that is present in nuclear fuel. This thesis offers different points of view on the possibility of americium transmutation. The first point of view elaborates simulations of americium-bearing facilities, namely nuclear data, a popular computational code and modeling techniques. The second point of view is focused on practical usage of the simulations to examine upper limit of americium in a specific reactor

  10. Transmutation of Americium in Fast Neutron Facilities

    OpenAIRE

    Zhang, Youpeng

    2011-01-01

    In this thesis, the feasibility to use a medium sized sodium cooled fast reactor fully loaded with MOX fuel for efficient transmutation of americium is investigated by simulating the safety performance of a BN600-type fast reactor loaded with different fractions of americium in the fuel, using the safety parameters obtained with the SERPENT Monte Carlo code. The focus is on americium mainly due to its long-term contribution to the radiotoxicity of spent nuclear fuel and its deterioration on c...

  11. Production of americium isotopes in France

    International Nuclear Information System (INIS)

    The program of productions of americium 241 and 243 isotopes is based respectively on the retreatment of aged plutonium alloys or plutonium dioxide and on the treatment of plutonium targets irradiated either in CELESTIN reactors for Pu-Al alloys or OSIRIS reactor for plutonium 242 dioxide. All the operations, including americium final purifications, are carried out in hot cells equipped with remote manipulators. The chemical processes are based on the use of extraction chromatography with hydrophobic SiO2 impregnated with extracting agents. Plutonium targets and aged plutonium alloys are dissolved in nitric acid using conventional techniques while plutonium dioxide dissolutions are performed routine at 300 grams scale with electrogenerated silver II in 4M HNO3 at room temperature. The separation between plutonium and americium is performed by extraction of Pu(IV) either on TBP/SiO2 or TOAHNO3/SiO2 column. Americium recovery from waste streams rid of plutonium is realized by chromatographic extraction of Am(III) using mainly TBP and episodically DHDECMP as extractant. The final purification of both americium isotopes uses the selective extraction of Am(VI) on HDDiBMP/SiO2 column at 60 grams scale. Using the overall process a total amount of 1000 grams of americium 241 and 100 grams of americium 243 has been produced nowadays and the AmO2 final product indicates a purity better than 98.5%

  12. Study of americium sorption by humic acids

    International Nuclear Information System (INIS)

    The results of investigation of influence of the cation content and acidity of soil solution on americium sorption by the humic acids have been shown. The most influence on the interphase distribution coefficient in the system 'humic acid - model soil solution' is caused by the presence of the iron (III), calcium ions and acidity of the solution. The increase of the sodium ions concentration in the solution makes an insignificant impact on the americium sorption. (Authors)

  13. Spectrochemical analysis of curium and americium samples

    International Nuclear Information System (INIS)

    Spectrochemical procedures have been developed to determine impurities in americium and curium samples. The simultaneous separation of many impurity elements from the base material (americium and curium) is carried out with extraction and extraction-chromatographic methods using di-2-ethylhexylphosphoric acid. It is shown that part of the elements are separated with extraction or sorption of americium and curium; the other part with the Talspeak process. Two fractions in the extraction chromatography and three fractions in the extraction separation of americium and curium, containing impurities, are analyzed separately by a.c. or d.c. arc spectrography. To increase the sensitivity of the spectrographic analysis and accelerate the burn-up of impurities from the crater of the carbon electrode bismuth fluoride and sodium chloride were used as chemically active substances. The extraction of impurities from weighed quantities of americium and curium samples of 5 to 10 mg permits the lower limit of determined impurity concentrations to be extended to 1 x 10-4 to 5 x 10-3% m/m. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Kimball, David Bryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Skidmore, Bradley Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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.

  15. Pyrochemical technology of plutonium and americium preparation and purification

    International Nuclear Information System (INIS)

    Pyrochemical tecnology of metallic plutonium and americium preparation and purification is considered. Investigations into plutonium dioxide reduction up to metal; plutonium electrolytic refining in molten salts; plutonium extraction from the molten salts and preparation of americium dioxide and metallic americium from its tetrafluoride are described

  16. Formation of americium and europium humate complexes

    International Nuclear Information System (INIS)

    Binding constants of americium and europium with a humic acid were determined to study if complex formation of trivalent actinide-humates affects dissolved species of the actinides in hydrosphere. The purified humic acid was characterized by means of UV-vis, IR, and pH titration, indicating high carboxylate capacity and low aromaticity. Binding constants of americium and europium humates were determined at pH 4.6 and 6.0 by solvent extraction using 241Am or 152Eu as a tracer. The binding constants for americium-humate obtained preliminarily suggest that complexes with humic acid are not negligible in speciation of trivalent actinides in hydrosphere. The obtained binding constants were nearly identical with those determined previously by the same procedures, but with humic acids of different origin and compositions. (author)

  17. Preparation of americium source for smoke detector

    International Nuclear Information System (INIS)

    This report describes the method developed for the preparation of 241Am source for smoke detector. Americium was electrodeposited from iso-propyl alcohol medium on silver backing. Thin layer of gold (few hundred micro gram thick) was plated on the americium source to make it safe for handling. The thickness of plated gold was such that the alpha radiations from the 241Am source could escape out of the gold layer and cause ionisation in the surrounding air. The performance of the prepared sources were checked in a smoke detector and was found to be satisfactory and comparable to the imported sources. (author). 1 refs., 2 figs., 1 tab

  18. Recovery of americium-241 from raffinates of plutonium purification columns

    International Nuclear Information System (INIS)

    Recovery and purification of americium from ion exchange raffinates generated during purification of aged plutonium is described. The method consists of the following stages: (i) co-precipitation of americium with kilogramme quantities of rare earth oxalates, (ii) destruction of oxalate and removal of residual plutonium from nitric acid medium using anion exchange process, (iii) preliminary separation of americium making use of its preferential uptake on an anion exchange column from thiocyanate medium and (iv) extraction of americium and remaining rare earths into di-(2-ethyl hexyl) phosphoric acid followed by preferential back washing of americium by lactic acid medium containing DTPA. (author)

  19. Selenide isotope generator for the Galileo mission

    International Nuclear Information System (INIS)

    A significantly improved thermoelectric generator has been developed to provide electric power for NASA's Galileo Mission in 1982. Nominal power requirements for Galileo will be about 450 watts at BOL (Beginning of Life), and this will be furnished by two Selenide Isotope Generators (SIG) each powered by a Multi Hundred Watt (MHW) radioisotopic heat source. A Ground Demonstration System (GDS) of a nominal 100 w(e) features a 3M - produced selenide ring module around a shortened MHW-dimensioned electrical heat source, newly developed axially-grooved heat pipes on a disc-shaped radiator, and other innovations which will allow a full-sized generator's weight to be held at about 90 lbs

  20. Cybernetic prediction of selenide Chevreul's phases

    International Nuclear Information System (INIS)

    The method of training a computer is used to forecast the possibility for the formation of selenide Chevreul's phases of the Asub(x)Bsub(6)Sesub(8) composition (where A is any chemical element, B-Mo, Cr, W, Re). The peculiarities of applying cybernetic forecasting systems in inorganic chemistry are considered. The critical temperature of transfer into the superconducting state of some phases forecasted is estimated

  1. 1976 Hanford americium exposure incident: psychological aspects

    International Nuclear Information System (INIS)

    Accidents involving exposure to radiation or radioactive materials may involve an unusual degree of emotional trauma. Methods that may be employed in dealing with such trauma are discussed in relation to a specific accident in which a radiation worker was injured and seriously contaminated with americium-241

  2. Americium separations from high salt solutions

    International Nuclear Information System (INIS)

    Americium (III) exhibits an unexpectedly high affinity for anion-exchange material from the high-salt evaporator bottoms solutions--an effect which has not been duplicated using simple salt solutions. Similar behavior is observed for its lanthanide homologue, Nd(III), in complex evaporator bottoms surrogate solutions. There appears to be no single controlling factor--acid concentration, total nitrate concentration or solution ionic strength--which accounts for the approximately 2-fold increase in retention of the trivalent ions from complex solutions relative to simple solutions. Calculation of species activities (i.e., water, proton and nitrate) in such concentrated mixed salt solutions is difficult and of questionable accuracy, but it is likely that the answer to forcing formation of anionic nitrate complexes of americium lies in the relative activities of water and nitrate. From a practical viewpoint, the modest americium removal needs (ca. 50--75%) from nitric acid evaporator bottoms allow sufficient latitude for the use of non-optimized conditions such as running existing columns filled with older, well-used Reillex HPQ. Newer materials, such as HPQ-100 and the experimental bifunctional resins, which exhibit higher distribution coefficients, would allow for either increased Am removal or the use of smaller columns. It is also of interest that one of the experimental neutral-donor solid-support extractants, DHDECMP, exhibits a similarly high level of americium (total alpha) removal from EV bottoms and is much less sensitive to total acid content than commercially-available material

  3. Decontaminaion of metals containing plutonium and americium

    International Nuclear Information System (INIS)

    Melt-slagging (melt-refining) techniques were evaluated as a decontamination and consolidation step for metals contaminated with oxides of plutonium and americium. Experiments were performed in which mild steel, stainless steel, and nickel contaminated with oxides of plutonium and americium were melted in the presence of silicate slags of various compositions. The metal products were low in contamination, with the plutonium and americium strongly fractionated to the slags. Partition coefficients (plutonium in slag/plutonium in steel) of 7 x 106 were measured with boro-silicate slag and of 3 x 106 with calcium, magnesium silicate slag. Decontamination of metals containing as much as 14,000 ppM plutonium appears to be as efficient as for metals with plutonium levels of 400 ppM. Staged extraction, that is, a remelting of processed metal with clean slag, results in further decontamination of the metal. The second extraction is effective with either resistance-furnace melting or electric-arc melting. Slag adhering to the metal ingots and in defects within the ingots is in the important contributors to plutonium retained in processed metals. If these sources of plutonium are controlled, the melt-refining process can be used on a large scale to convert highly contaminated metals to homogeneous and compact forms with very low concentrations of plutonium and americium. A conceptual design of a melt-refining process to decontaminate plutonium- and americium-contaminated metals is described. The process includes single-stage refining of contaminated metals to produce a metal product which would have less than 10 nCi/g of TRU-element contamination. Two plant sizes were considered. The smaller conceptual plant processes 77 kg of metal per 8-h period and may be portable.The larger one processes 140 kg of metal per 8-h period, is stationary, and may be near te maximum size that is practical for a metal decontamination process

  4. One Pot Synthetic Method of New Keto Diphenyl Selenide Compounds

    OpenAIRE

    Youcef Mechehoud; Benayache, F.; Benayache, S.; Mosset, P.

    2010-01-01

    A series of hitherto unreported mono- and di-keto diphenyl selenides have been efficiently synthesized in high yields by treatment of diphenyl selenide (1) with appropriately substituted acyl chloride using anhydrous aluminum chloride as catalyst and methylene chloride as solvent. The structures of the synthesized compounds have been confirmed by elemental and spectral analysis.

  5. Status of Americium-241 recovery at Rocky Flats Plant

    International Nuclear Information System (INIS)

    This paper is presented in two parts: Part I, Molten Salt Extraction of Americium from Molten Plutonium Metal, and Part II, Aqueous Recovery of Americium from Extraction Salts. The Rocky Flats recovery process used for waste salts includes (1) dilute hydrochloric acid dissolution of residues; (2) cation exchange to convert from the chloride to the nitrate system and to remove gross amounts of monovalent impurities; (3) anion exchange separation of plutonium; (4) oxalate precipitation of americium; and (5) calcination of the oxalate at 6000C to yield americium oxide. The aqueous process portion describes attempts to improve the recovery of americium. The first part deals with modifications to the cation exchange step; the second describes development of a solvent extractions process that will recovery americium from residues containing aluminium as well as other common impurities. Results of laboratory work are described. 3 figures, 6 tables. (DP)

  6. Plutonium and americium in soil organic matter

    International Nuclear Information System (INIS)

    A gley soil from west Cumbria, with specific activities in its surface horizon of 5-10 kBq kg-1239,240Pu and comparable 241Am levels, has been used as a source of actinide-enriched organic fractions. Humic and fulvic acids were isolated by conventional alkali extraction and investigated by gel filtration, treatment with organic solvents and differential flocculation procedures. All these techniques are capable of resolving the organics into two or more fractions, with specific activities up to 80 kBq kg-239,240Pu. There is evidence for differentiation of plutonium and americium, with americium being concentrated, to some extent, in the lower molecular weight fractions from gel filtration. (author)

  7. Limiting pump intensity for sulfur-doped gallium selenide crystals

    International Nuclear Information System (INIS)

    High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium selenide)

  8. Incentives for transmutation of americium in thermal reactors

    International Nuclear Information System (INIS)

    This report describes possible benefits when americium is irradiated in a thermal reactor. If all plutonium is partitioned from spent fuel, americium is the main contributor to the radiotoxicity of spent fuel upto several thousands of years of storage. It is shown that americium can be transmuted to other nuclides upon irradiation in a thermal reactor, leading to a 50% reduction of the radiotoxicity of neptunium, which can be an important contributor to the dose due to leakage of nuclides after one million years of storage. The radiotoxicity of americium can be reduced considerably after irradiation for 3 to 6 years in a thermal reactor with thermal neutron flux of 1014 cm-2s-1. The strongly α and neutron emitting transmutation products can most probably not be recycled again, so a transmutation process is suggested in which americium is irradiated for 3 to 6 years and then put to final storage. It is shown that the radiotoxicity of the transmuation products after a storage time of about one hundred years can be considerably reduced compared to the radiotoxicity of the initial americium. The same holds for the α activity and heat emission of the transmutation products. Because plutonium in spent fuel contributes for about 80% to the radiotoxicity upto 105 years of storage, recycling and transmutation of plutonium has first priority. Transmutation of americium is only meaningful when the radiotoxicity of plutonium is reduced far below the radiotoxicity of americium. (orig.)

  9. Americium transfer studies using hollow fiber/extractant membranes

    International Nuclear Information System (INIS)

    Americium can be removed from low acid/high nitrate feeds using hollow fiber membrane modules. Americium can be concentrated in the stripping solution. (Maximum observed concentration was a factor of 3.1). Accurel hollow fibers are less prone to leakage problems

  10. Improved thermoelectric performance of Nb-doped lead selenide

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yemao; Chen, Zhen; Xin, Caini [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Pei, Yanzhong [School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Zhou, Min, E-mail: mzhou@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Huang, Rongjin [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Li, Laifeng, E-mail: laifengli@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-05

    Highlights: • Thermoelectric performance of Nb-doped lead selenide was investigated. • Higher Seebeck coefficient was obtained in Nb-doped lead selenide. • The grain sizes are about 100-300 nm according to SEM. • There is little lattice thermal conductivity decrease. - Abstract: In present work, niobium is used as donor impurity in lead selenide to increase carrier concentration. Thermoelectric transport properties of n-type Pb{sub 1.04−x}Nb{sub x}Se are investigated from room temperature to 673 K. Higher Seebeck coefficient is reached by Nb-doping in lead selenide compared to other dopants. The Seebeck coefficient enhancement comes from band modification by Nb-doping, which results in the density of states effective mass increase. With the Seebeck coefficient enhancement, the dimensionless figure of merit ZT reaches ∼1.1 at 673 K.

  11. Electronic structure of compressed americium metal

    Czech Academy of Sciences Publication Activity Database

    Kolorenč, Jindřich; Shick, Alexander; Caciuffo, R.

    Cambridge: Cambridge University Press,, 2012 - (Anderson, D.; Boot, C.; Burns, P.), s. 177-182. (Materials Research Society Symposium Proceedings. 1444). ISBN 978-1-60511-421-7. ISSN 0272-9172. [2012 MRS Spring Meeting. Sacramento (CA), 09.04.2012-13.04.2012] R&D Projects: GA ČR(CZ) GAP204/10/0330; GA AV ČR IAA100100912 Institutional research plan: CEZ:AV0Z10100520 Keywords : americium * X-ray spectroscopy * LDA+DMFT Subject RIV: BM - Solid Matter Physics ; Magnetism http://journals.cambridge.org/article_S1946427412009463

  12. Electrochemical oxidation of americium in nitric medium: study of reaction mechanisms; Oxydation de l'americium par voie electrochimique: etude des mecanismes

    Energy Technology Data Exchange (ETDEWEB)

    Picart, S.; Chartier, D.; Donnet, L.; Adnet, J.M. [CEA Valrho, (DCC/DRRV/SPHA), 30 - Marcoule (France)

    2000-07-01

    One alternative selected by the CEA for partitioning minor actinides from aqueous solutions containing fission products is the selective extraction of oxidized americium. This is the SESAME process (Selective Extraction and Separation of Americium by Means of Electrolysis) aimed to convert americium to oxidation state (VI) and then extract it with a specific extractant of high valences. This paper presents the study of the electrochemical oxidation of americium in nitric medium which represents an important stage of the process. The reaction can be divided into two main steps: oxidation of americium (III) to americium (IV), and then of americium (IV) to americium (VI). For the first oxidation step, a ligand L is needed to stabilize the intermediate species americium (IV) which disproportionates in its free form into americium (III) and (V). Phospho-tungstate or silico-tungstate are appropriate ligands because they are stable in concentrated nitric acid and show a great affinity for metallic cations at oxidation state (IV) (Table 1 lists the stability constants of americium (IV) complexes). The presence of the lacunary poly-anion lowers the potential of the americium (IV) / americium (Ill) redox pair (see Figure 5 for the diagram of the apparent formal potential of americium versus ligand concentration). This makes it thermodynamically possible to oxidize americium (III) into americium (IV) at the anode of an electrolyzer in nitric acid. For the second oxidation step, a strong oxidant redox mediator, like silver (II), is needed to convert complexed americium at oxidation state (IV) to oxidation state (V). The AmVL complex is then hydrolyzed to yield americyle (V) aqua ion. A spectroscopic Raman study with {sup 18}O labeled species showed that the oxygen atoms of the americyle moiety came from water. This indicates that water hydrolyzes the americium (V) complex to produce americyle (V) aqua ion, AmO{sub 2}{sup +}. This cation reacts with silver (Il) to give

  13. Modelling of americium stripping in the EXAm process

    International Nuclear Information System (INIS)

    The EXAm process aims at recovering americium alone contained in the PUREX raffinate. The americium stripping model has been revised to take into account a change of stripping aqueous phase and up-to-date experimental results conducted within DRCP to improve knowledge about complexes. This work represents a first approximation at modelling americium stripping. The modelling work has led to synthesize the knowledge on chemical phenomenology and adopt assumptions that best reflect experimental results. The modelling has been implemented in PAREX code in order to simulate this step to prepare and understand tests to be carried out in mixer settlers. (authors)

  14. Higher Americium Oxidation State Research Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Law, Jack D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Goff, George S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lumetta, Gregg J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinkov, Sergey I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shehee, Thomas C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hobbs, David T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    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

  15. Superconductivity in alkali metal intercalated iron selenides.

    Science.gov (United States)

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  16. Amphoteric properties of gold in zinc selenide

    International Nuclear Information System (INIS)

    Hall effect, electric conductivity, and charge carriers mobility in n-ZnSe single crystals doped with gold during the process of a long-term high-temperature annealing in Zn+Au melt with various Au contents were investigated in the temperature range from 77 to 300 K. It has been established that, at low gold concentration, Au atoms form mainly donor-type interstitial Aui defects. The increase of Au concentration in Zn+Au melt leads to the formation of both simple AuZn defects and associative acceptors (AuZn-Aui) (AuZn-DZn), and (AuZn-VSe). These defects determine electrical properties of the crystals and they are responsible for the complex structure of excitonic and impurity radiation spectra. The influence of dopant concentration on both electrical and luminescent properties of n-ZnSe:Zn:Au crystals is investigated. The observed variations of electrical and luminescent properties are due to amphoteric properties of gold impurity in zinc selenide

  17. Superconductivity in alkali metal intercalated iron selenides

    Science.gov (United States)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  18. Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors

    International Nuclear Information System (INIS)

    Luminescent quantum dots were synthesized using bacterially derived selenide (SeII−) as the precursor. Biogenic SeII− was produced by the reduction of SeIV by Veillonella atypica and compared directly against borohydride-reduced SeIV for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII− formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII− included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII− is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, ‘green’ synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams. (paper)

  19. Mixed chelation therapy for removal of plutonium and americium

    International Nuclear Information System (INIS)

    Iron-binding compounds, 2,3-dihydroxybenzoic acid (DHBA), 2-hydroxybenzoic acid (HBA), and 2-(acetyloxy)benzoic acid (ABA), were tested for their ability to remove americium and plutonium from rats following intraperitioneal injection of the radionuclides as citrates (pH 5). Treatments, 2 mmol/kg, were given on days 3, 6, 10, 12 and 14 following the actinide injection. DHBA and HBA caused about a 20% decrease in liver retention of americium compared to the control value, and DHB caused a similar effect for plutonium. The above agents, co-administered with 0.5 mmol polyaminopolycarboxylic acid (PAPCA)-type chelons, did not change tissue retention of americium and plutonium from that due to the PAPCAs alone. Administration of americium and plutonium to the same rats is useful for studying removal agents since the two actinides behave independently in their biological disposition and response to removal

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Americium/Curium Disposition Life Cycle Planning Study

    International Nuclear Information System (INIS)

    At the request of the Department of Energy Savannah River Office (DOE- SR), Westinghouse Savannah River Company (WSRC) evaluated concepts to complete disposition of Americium and Curium (Am/Cm) bearing materials currently located at the Savannah River Site (SRS)

  2. Gamma-sources on the basis of metallic americium-241

    International Nuclear Information System (INIS)

    A batch of gamma-radiation sources has been manufactured from metallic americium-241 of isotopic purity, its activity varying from 0.08 to 0.93 GBq. The cores of the sources are high-purity americium metal condensate on a tantalum or stainless steel substrate prepared by thermal decomposition of 241Pu-241Am alloy in a high vacuum. 7 refs., 1 tab

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

    International Nuclear Information System (INIS)

    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

  4. 1976 Hanford americium-exposure incident: external decontamination procedures

    International Nuclear Information System (INIS)

    An accident resulted in the deposition on an injured workman's skin surfaces, in acid-burned areas and in lacerations, of something in excess of 6 mCi americium-241. The external decontamination procedures used, the change in americium content of the skin during the course of treatment, and some of the unusual problems encountered from the extrusion of foreign material and flaking of skin and scar tissue are described

  5. Electrochemical oxidation of americium in nitric medium: study of reaction mechanisms

    International Nuclear Information System (INIS)

    One alternative selected by the CEA for partitioning minor actinides from aqueous solutions containing fission products is the selective extraction of oxidized americium. This is the SESAME process (Selective Extraction and Separation of Americium by Means of Electrolysis) aimed to convert americium to oxidation state (VI) and then extract it with a specific extractant of high valences. This paper presents the study of the electrochemical oxidation of americium in nitric medium which represents an important stage of the process. The reaction can be divided into two main steps: oxidation of americium (III) to americium (IV), and then of americium (IV) to americium (VI). For the first oxidation step, a ligand L is needed to stabilize the intermediate species americium (IV) which disproportionates in its free form into americium (III) and (V). Phospho-tungstate or silico-tungstate are appropriate ligands because they are stable in concentrated nitric acid and show a great affinity for metallic cations at oxidation state (IV) (Table 1 lists the stability constants of americium (IV) complexes). The presence of the lacunary poly-anion lowers the potential of the americium (IV) / americium (Ill) redox pair (see Figure 5 for the diagram of the apparent formal potential of americium versus ligand concentration). This makes it thermodynamically possible to oxidize americium (III) into americium (IV) at the anode of an electrolyzer in nitric acid. For the second oxidation step, a strong oxidant redox mediator, like silver (II), is needed to convert complexed americium at oxidation state (IV) to oxidation state (V). The AmVL complex is then hydrolyzed to yield americyle (V) aqua ion. A spectroscopic Raman study with 18O labeled species showed that the oxygen atoms of the americyle moiety came from water. This indicates that water hydrolyzes the americium (V) complex to produce americyle (V) aqua ion, AmO2+. This cation reacts with silver (Il) to give americyle (VI) ion. Figure

  6. Complexation of americium with humic acid

    International Nuclear Information System (INIS)

    As a part of the interlaboratory comparison exercise for the complexation of humic acid and colloid generation (COCO-Club activities) in the CEC project MIRAGE-II, the complexation of americium with humic acid has been studied in our laboratory. Two humic acids were used for the study: Aldrich-HA(H+) which is a reference humic acid of the COCO-Club and Bradford-HA(H+) from Lake Bradford, Florida. A wide concentration range of humic acid and different ratios of Am to humic acid have been investigated between pH 5 and 6 with the ionic strength of 0.1 M and 1.0 M. The complexation has been studied by UV-spectroscopy, Laser-induced Photoacoustic Spectroscopy (LPAS) and ultrafiltration. LPAS is used for the submicromolar concentration range where the sensitivity of UV spectroscopy is not accessible. Ultrafiltration is used for low Am to humic acid ratios where both spectroscopic methods are not applicable. Varying the humic acid concentration over three orders of magnitude, only a 1:1 type of binding is observed. No significant variation of the stability constant is found in the investigated range of pH and ionic strength. However, the precipitation tendency and the loading capacity of humic acid are found to depend sensitively on pH and ionic strength. The complexation study provides a deep insight into the influence of humic acid on the migration behaviour of fission products and actinides in the geosphere. (orig.)

  7. Analysis of BWR lattices to recycle americium

    International Nuclear Information System (INIS)

    This study was carried out to assess the ability to eliminate meaningful quantities of americium in a primarily thermal neutron flux by 'spiking' modern BWR fuel with this minor actinide (MA). The studies carried out so far include the simulation of modern 10 x 10 BWR lattices employing the Westinghouse lattice physics code PHOENIX-4 alongside validation studies using MCNP5 models of the same lattices that were spatially depleted via the MONTEBURNS code coupling to ORIGEN. When considering the total inventory of minor actinides in Am-spiked pins, excluding isotopes of uranium and plutonium, the results indicate that a reduction of approximately 50% or more in the total mass inventory of these minor actinides is viable within the selected pins. Therefore, these preliminary results have encouraged the extension of this work to the development of improved lattice designs to help optimize the transmutation rates as well as absolute MA inventory reductions. The ultimate goal being to design batches of these advanced BWR bundles alongside multi-cycle core reload strategies. (authors)

  8. Applicability of insoluble tannin to treatment of waste containing americium

    International Nuclear Information System (INIS)

    The applicability of insoluble tannin adsorbent to the treatment of aqueous waste contaminated with americium has been investigated. Insoluble tannin is considered highly applicable because it consists of only carbon, hydrogen and oxygen and so its volume can be easily reduced by incineration. This report describes measurements of the americium distribution coefficient in low concentration nitric acid. The americium distribution coefficients were found to decrease with increasing concentration of nitric acid and sodium nitrate, and with increasing temperature. At 25 C in 2.0 x 10-3 M HNO3, the distribution coefficient was found to be 2000 ml g-1. The adsorption capacity was determined by column experiments using europium as a simulant of americium, and found to be 7 x 10-3 mmol g-1-dried tannin in 0.01 M HNO3 at 25 C, which corresponds to approximately 1.7 mg-241Am/g-adsorbent(dried). The prospect of applying the adsorbent to the treatment of aqueous waste contaminated with americium appears promising. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Salvage of plutonium-and americium-contaminated metals

    International Nuclear Information System (INIS)

    Melt-slagging techniques were evaluated as a decontamination and consolidation step for metals contaminated with oxides of plutonium and americium. Experiments were performed in which mild steel, stainless steel, and nickel metals contaminated with oxides of plutonium and americium were melted in the presence of silicate slags of various compositions. The metal products were low in contamination, with the plutonium and americium strongly fractionated to the slags. Partition coefficients (plutonium in slag/plutonium in steel) of 7*10/sup 6/ with borosilicate slag and 3*10/sup 6/ for calcium, magnesium silicate slag were measured. Decontamination of metals containing as much as 14,000 p.p.m. plutonium appears to be as efficient as that of metals with plutonium levels of 400 p.p.m. Staged extraction, that is, a remelting of processed metal with clean slag, results in further decontamination of the metal. 10 refs

  11. Uptake of americium-241 by algae and bacteria

    International Nuclear Information System (INIS)

    The uptake of americium by three algae, scenedesmus obliquus, selenastrum capricomutum and chlorella pyrenosdosa and a bacterium aeromonas hydrophila was studied. Live and fixed cells of each algal species and live bacterial cells were used. it is shown that algae and bacteria concentrate americium 241 to a high degree which makes them important links in the biomagnification phenomenon which may ultimately lead to a human hazard and be potentially important in recycling Am 241 in the water column and mobilization from sediments. Chemical fixation of algal cells caused increased uptake which indicated that uptake is by passive diffusion and probably due to chemical alteration of surface binding sites. (U.K.)

  12. Americium incineration by recycling in target rods using coated particles

    International Nuclear Information System (INIS)

    This paper proposes a type of target rod based on the use of coated particles, for an efficient incineration of americium in nuclear reactors. The analysis takes advantage of the experience gained in the past from long duration irradiation without damage of coated particles with plutonium oxide kernels. A conservative theoretical evaluation of the gas pressure inside the coated particles at the end of irradiation allows comparing the well known conditions of the plutonium oxide particles which were successfully irradiated to high burn-up, with a preliminary design of americium oxide particles. (authors)

  13. Mechanochemical synthesis of nanocrystalline lead selenide. Industrial approach

    Energy Technology Data Exchange (ETDEWEB)

    Achimovicova, Marcela; Balaz, Peter [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Geotechnics; Durisin, Juraj [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Materials Research; Daneu, Nina [Josef Stefan Institute, Ljubljana (Slovenia). Dept. for Nanostructured Materials; Kovac, Juraj; Satka, Alexander [Slovak Univ. of Technology and International Laser Centre, Bratislava (Slovakia). Dept. of Microelectronics; Feldhoff, Armin [Leibniz Univ. Hannover (Germany). Inst. fuer Physikalische Chemie und Elektrochemie; Gock, Eberhard [Technical Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. of Mineral and Waste Processing and Dumping Technology

    2011-04-15

    Mechanochemical synthesis of lead selenide PbSe nanoparticles was performed by high-energy milling of lead and selenium powder in a laboratory planetary ball mill and in an industrial eccentric vibratory mill. Structural properties of the synthesized lead selenide were characterized using X-ray diffraction that confirmed crystalline nature of PbSe nanoparticles. The average size of PbSe crystallites of 37 nm was calculated from X-ray diffraction data using the Williamson-Hall method. The methods of particle size distribution analysis, specific surface area measurement, scanning electron microscopy and transmission electron microscopy were used for characterization of surface, mean particle size, and morphology of PbSe. An application of industrial mill verified a possibility of the synthesis of a narrow bandgap semiconductor PbSe at ambient temperature and in a relatively short reaction time. (orig.)

  14. Strukturelle und kinetische Charakterisierung von Ruthenium-Selenid Katalysatoren

    OpenAIRE

    Racz, Alexander

    2011-01-01

    Die Arbeit befasst sich mit Kohlenstoff-geträgerten Ruthenium-Selenid (RuSex) Katalysatoren für die kathodische Sauerstoffreduktion in Methanol-Brennstoffzellen. Ziel dieser Arbeit war es, RuSex/C Katalysatoren zu synthetisieren, welche eine vergleichbare elektrochemische Aktivität wie kommerzielle Pt/C Katalysatoren aufweisen. Neben der Optimierung der Synthese stand die elektrochemische Charakterisierung der Katalysatoren im Hinblick auf die elektrochemisch aktive Oberfläche, sowie deren Ak...

  15. Long-term physical ageing in vitreous arsenic selenides

    International Nuclear Information System (INIS)

    Effects of long-term physical aging (approx 20 years) studied in vitreous arsenic selenides using differential scanning calorimetry are compared with conventional short-term physical aging (up to 1 year). It is shown that these effects differ not only by their amplitudes but also by compositional dependences. These results clearly testify in a favour of a sufficient difference in microstructural origin for short- and long-term physical aging in chalcogenide glasses

  16. Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

    KAUST Repository

    Xia, Chuan

    2015-11-05

    Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

  17. Synthesis of cadmium selenide colloidal quantum dots in aquatic medium

    International Nuclear Information System (INIS)

    Cadmium selenide nanocrystals were prepared in water phase through facile wet chemistry technique with thioglycolic acid (TGA) acting as capping agent. Structures were characterized using X-ray diffraction (XRD), UV-vis absorption and photoluminescence spectroscopies. Depending on synthesis conditions nanoparticles exhibit photoluminescence with maximum in the region of 580 – 680 nm. Influence of technological parameters and component concentrations on nanocrystals average size and properties was studied

  18. Coulometric titration at low temperatures-nonstoichiometric silver selenide

    OpenAIRE

    Beck, Gesa K.; Janek, Jürgen

    2003-01-01

    A modified coulometric titration technique is described for the investigation of nonstoichiometric phases at low temperatures. It allows to obtain titration curves at temperatures where the conventional coulometric titration technique fails because of too small chemical diffusion coefficients of the mobile component. This method for indirect coulometric titration is applied to silver selenide between -100 and 100 °C. The titration curves are analyzed on the basis of a defect chemical model an...

  19. Raman study of gallium selenide single crystal oxidation

    Directory of Open Access Journals (Sweden)

    O.A. Balitskii

    2001-06-01

    Full Text Available The Raman investigations on thermally oxidized gallium selenide were conducted. It was established that the oxidation of the GaSe involves the formation of a-modification of Ga2Se3 at the temperature up to 450 °C. The Ga-(O2 complexes are also detected at this temperature but the formation of crystalline gallium oxide takes place at the temperature of 800°C

  20. 1976 Hanford americium exposure incident: overview and perspective

    International Nuclear Information System (INIS)

    Salient features of the 1976 Hanford americium exposure incident are discussed. Comparisons are made with previous human and animal exposure data, and conclusions drawn relative to the injured workman, to health physics practices, and to the adequacy of current exposure limits

  1. Americium retention by the smectite hectorite

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Clay minerals may play an important role in a high level nuclear waste disposal site. Smectites may be major components of backfill material used to enhance the retention properties of engineered barriers. Furthermore, they have also been detected in the alteration layer of nuclear waste glass corroded in laboratory experiments. For example, the smectite hectorite (Na0.33[Mg2.67Li0.33Si4O10(OH)2]) was identified as phase forming upon waste matrix dissolution and subsequent reprecipitation. Smectites are known to be highly reactive with respect to cations in aqueous systems. Several distinct molecular scale binding mechanisms may operate, but the most effective retention may occur by incorporation in the bulk structure, especially if a (meta)stable solid solution forms. Investigations showed the possibility to incorporate Lu(III) in a clay-like octahedral site in hectorite by coprecipitation. Furthermore, luminescence studies on hectorite synthesized in the presence of Cm(III) or Eu(III) were consistent with an incorporation in the bulk structure. However, structural data such as coordination numbers and bond lengths are still missing for the actinides. In the present study, Am(III) was coprecipitated with and adsorbed on hectorite to decipher the actual retention mechanism(s). Hectorite was synthesized in the presence of Am(III) (sample AmCopHec) from an Am-containing brucite precursor phase. Briefly, brucite was freshly precipitated in the presence of Am(III) (Am:Mg molar ratio of 1:1175) and washed. The resulting sol was aged in a tightly closed vessel in the presence of LiF and silica sol for several days at 90 C. Separately, an Am-containing brucite phase (sample AmCopBru) was prepared under identical conditions as described above, and the americium aqua ions were adsorbed on hectorite (m/V = 2 g/L, [Am(III)]tot = 105 μmol/L, 0.5 mol/L NaClO4, pH = 6.4(1), sample AmSorbHec) and used as reference samples. X

  2. Synthesis and characterization of uranium-americium mixed oxides

    International Nuclear Information System (INIS)

    Americium isotopes represent a significant part of high-level and long-lived nuclear waste in spent fuels. Among the envisaged reprocessing scenarios, their transmutation in fast neutron reactors using uranium-americium mixed-oxide pellets (U1-xAmxO2±δ) is a promising option which would help decrease the ecological footprint of ultimate waste repository sites. In this context, this thesis is dedicated to the study of such compounds over a wide range of americium contents (7.5 at.% ≤ Am/(U+Am) ≤ 70 at.%), with an emphasis on their fabrication from single-oxide precursors and the assessment of their structural and thermodynamic stabilities, also taking self-irradiation effects into account. Results highlight the main influence of americium reduction to Am(+III), not only on the mechanisms of solid-state formation of the U1-xAmxO2±δ solid solution, but also on the stabilization of oxidized uranium cations and the formation of defects in the oxygen sublattice such as vacancies and cub-octahedral clusters. In addition, the data acquired concerning the stability of U1-xAmxO2±δ compounds (existence of a miscibility gap, vaporization behavior) were compared to calculations based on new thermodynamic modelling of the U-Am-O ternary system. Finally, α-self-irradiation-induced structural effects on U1-xAmxO2±δ compounds were analyzed using XRD, XAS and TEM, allowing the influence of americium content on the structural swelling to be studied as well as the description of the evolution of radiation-induced structural defects. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    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.

  4. Sodium selenide toxicity is mediated by O2-dependent DNA breaks.

    Directory of Open Access Journals (Sweden)

    Gérald Peyroche

    Full Text Available Hydrogen selenide is a recurrent metabolite of selenium compounds. However, few experiments studied the direct link between this toxic agent and cell death. To address this question, we first screened a systematic collection of Saccharomyces cerevisiae haploid knockout strains for sensitivity to sodium selenide, a donor for hydrogen selenide (H(2Se/HSe(-/Se(2-. Among the genes whose deletion caused hypersensitivity, homologous recombination and DNA damage checkpoint genes were over-represented, suggesting that DNA double-strand breaks are a dominant cause of hydrogen selenide toxicity. Consistent with this hypothesis, treatment of S. cerevisiae cells with sodium selenide triggered G2/M checkpoint activation and induced in vivo chromosome fragmentation. In vitro, sodium selenide directly induced DNA phosphodiester-bond breaks via an O(2-dependent reaction. The reaction was inhibited by mannitol, a hydroxyl radical quencher, but not by superoxide dismutase or catalase, strongly suggesting the involvement of hydroxyl radicals and ruling out participations of superoxide anions or hydrogen peroxide. The (•OH signature could indeed be detected by electron spin resonance upon exposure of a solution of sodium selenide to O(2. Finally we showed that, in vivo, toxicity strictly depended on the presence of O(2. Therefore, by combining genome-wide and biochemical approaches, we demonstrated that, in yeast cells, hydrogen selenide induces toxic DNA breaks through an O(2-dependent radical-based mechanism.

  5. Liquid-liquid extraction separation and determination of plutonium and americium

    International Nuclear Information System (INIS)

    A procedure is described for the determination of plutonium and americium after their initial separation on barium sulfate. The barium sulfate is dissolved in perchloric acid and the antinides and lanthanides are extracted into bis(2-ethylhexyl)phosphoric acid (HDEHP). Americium along with other tervalent actinides and lanthanides is stripped from HDEHP with nitric acid. The lanthanides are removed on a column of HDEHP supported on Teflon powder, and the americium and other tervalent actinides are electrodeposited for their determination by α spectrometry. The plutonium is stripped with nitric acid after reduction to the tervalent state with 2,5-di-tert-butylhydroquinone and electrodeposited for α spectrometry. Decontamination factors for plutonium and americium from each other and from other α emitters are 104 to 105. Two hours are required for the liquid-liquid extraction separations of plutonium and americium from eight samples. Recoveries of americium and plutonium through the HDEHP separatons are 99% and 95%, respectively

  6. Calculational study on irradiation of americium fuel samples in the Petten High Flux Reactor

    International Nuclear Information System (INIS)

    A calculational study on the irradiation of americium samples in the Petten High Flux Reactor (HFR) has been performed. This has been done in the framework of the international EFTTRA cooperation. For several reasons the americium in the samples is supposed to be diluted with a neutron inert matrix, but the main reason is to limit the power density in the sample. The low americium nuclide density in the sample (10 weight % americium oxide) leads to a low radial dependence of the burnup. Three different calculational methods have been used to calculate the burnup in the americium sample: Two-dimensional calculations with WIMS-6, one-dimensional calculations with WIMS-6, and one-dimensional calculations with SCALE. The results of the different methods agree fairly well. It is concluded that the radiotoxicity of the americium sample can be reduced upon irradiation in our scenario. This is especially the case for the radiotoxicity between 100 and 1000 years after storage. (orig.)

  7. Double-Diffusive Convection During Growth of Halides and Selenides

    Science.gov (United States)

    Singh, N. B.; Su, Ching-Hua; Duval, Walter M. B.

    2015-01-01

    Heavy metal halides and selenides have unique properties which make them excellent materials for chemical, biological and radiological sensors. Recently it has been shown that selenohalides are even better materials than halides or selenides for gamma-ray detection. These materials also meet the strong needs of a wide band imaging technology to cover ultra-violet (UV), midwave infrared wavelength (MWIR) to very long wavelength infrared (VLWIR) region for hyperspectral imager components such as etalon filters and acousto-optic tunable filters (AO). In fact AOTF based imagers based on these materials have some superiority than imagers based on liquid crystals, FTIR, Fabry-Perot, grating, etalon, electro-optic modulation, piezoelectric and several other concepts. For example, broadband spectral and imagers have problems of processing large amount of information during real-time observation. Acousto-Optic Tunable Filter (AOTF) imagers are being developed to fill the need of reducing processing time of data, low cost operation and key to achieving the goal of covering long-wave infrared (LWIR). At the present time spectral imaging systems are based on the use of diffraction gratings are typically used in a pushbroom or whiskbroom mode. They are mostly used in systems and acquire large amounts of hyperspectral data that is processed off-line later. In contrast, acousto-optic tunable filter spectral imagers require very little image processing, providing new strategies for object recognition and tracking. They are ideally suited for tactical situations requiring immediate real-time image processing. But the performance of these imagers depends on the quality and homogeneity of acousto-optic materials. In addition for many systems requirements are so demanding that crystals up to sizes of 10 cm length are desired. We have studied several selenides and halide crystals for laser and AO imagers for MWIR and LWIR wavelength regions. We have grown and fabricated crystals of

  8. Neptunium and americium control for international non-proliferation regime

    International Nuclear Information System (INIS)

    It was decided in the IAEA Board of Governors Meeting held in Sept. 1999 that Neptunium and Americium could be diverted for manufacturing nuclear weapon or explosives, so that appropriate measures should be taken for the prevention of proliferation of these materials. It is expected to take relatively long time for settling down the aligned system dealing with the above materials because the present regulatory statement was prepared on the basis of voluntary offers from the States concerned. The necessity of preventive measures is being convinced among Member States, but it would not be easy to take voluntary participation in detail because of their respective interests. It is expected that this paper could contribute to the effective response as to the international commitments as well as for protecting the domestic nuclear industry and R and D area through analysis on the IAEA's approach on Neptunium and Americium

  9. Thermophysical properties of americium-containing barium plutonate

    International Nuclear Information System (INIS)

    Polycrystalline specimens of americium-containing barium plutonate have been prepared by mixing the appropriate amounts of (Pu0.91Am0.09)O2 and BaCO3 powders followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. Elastic moduli were determined from longitudinal and shear sound velocities. Debye temperature was also determined from sound velocities and lattice parameter measurements. Thermal conductivity was calculated from measured density at room temperature, literature values of heat capacity and thermal diffusivity measured by laser flash method in vacuum. Thermal conductivity of americium-containing barium plutonate was roughly independent of temperature and registered almost the same magnitude as that of BaPuO3 and BaUO3. (author)

  10. 1976 Hanford americium-exposure incident: decontamination and treatment facility

    International Nuclear Information System (INIS)

    An injured worker, contaminated with over 6 mCi of americium-241, required special treatment and housing for 4 months. This paper is a description of the design and management of the facility in which most of the treatment and housing occurred. The problems associated with contamination control, waste handling, supplies, and radiological concerns during the two-stage transfer of the patient from a controlled situation to his normal living environment are discussed in detail

  11. Recycling heterogeneous americium targets in a boiling water reactor

    International Nuclear Information System (INIS)

    One of the limiting contributors to the heat load constraint for a long term spent fuel repository is the decay of americium-241. A possible option to reduce the heat load produced by Am-241 is to eliminate it via transmutation in a light water reactor thermal neutron environment, in particular, by taking advantage of the large thermal fission cross section of Am-242 and Am-242m. In this study we employ lattice loading optimization techniques to define the loadings and arrangements of fuel pins with blended americium and uranium oxide in boiling water reactor bundles, specifically, by defining the incineration of pre-loaded americium as an objective function to maximize americium transmutation. Subsequently, the viability of these optimized lattices is tested by assembling them into bundles with Am-spiked fuel pins and by loading these bundles into realistic three-dimensional BWR core-wide simulations that model multiple reload cycles and observe standard operational constraints. These simulations are possible via our collaboration with the Westinghouse Electric Co. which facilitates the use of industrial-caliber design tools such as the PHOENIX-4/POLCA-7 sequence and the Core Master 2 GUI work environment for fuel management. The resulting analysis confirms the ability to axially uniformly eliminating roughly 90% of the pre-loaded inventory of recycled Am-241 in BWR bundles with heterogeneous target pins. This high level of incineration was achieved within three to four 18-month operational cycles, which is equivalent to a typical in-core residence time of a BWR bundle.

  12. Ingestion Pathway Transfer Factors for Plutonium and Americium

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Gut uptake factors for plutonium, americium and curium

    International Nuclear Information System (INIS)

    Data on estimates of the absorption of plutonium, americium and curium from the human gut based on measurements of uptake in other mammalian species are reviewed. It is proposed that for all adult members of the public ingesting low concentrations of plutonium in food and water, 0.05% would be an appropriate value of absorption except when the conditions of exposure are known and a lower value can be justified. For dietary intakes of americium and curium, the available data do not warrant a change from the ICRP value of 0.05%. For newborn children ingesting americium, curium and soluble forms of plutonium, a value of 1% absorption is proposed for the first 3 months of life during which the infant is maintained on a milk diet. It is proposed that a value of 0.5% should be used for the first year of life to take account of the gradual maturation of the gut. In considering the ingestion of insoluble oxides of plutonium by infants, it is proposed that absorption is taken as 0.1% for the first 3 months and 0.05% for the first year. (author)

  14. Lithium insertion in indium selenide films: application to microbatteries

    Energy Technology Data Exchange (ETDEWEB)

    Julien, C. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Khelfa, A. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Benramdane, N. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Guesdon, J.P. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Dzwonkowski, P. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Samaras, I. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France)); Balkanski, M. (Lab. de Physique des Solides, Univ. Pierre et Marie Curie, 75 Paris (France))

    1994-04-10

    Indium selenide films are formed on silica slides and silicon wafers using a flash evaporation technique in which the material source stoichiometry is modified to obtain In[sub p]Se[sub q] films with various compositions. The structural and optical properties of indium selenide films are reported. These characterizations have shown that, using different growth conditions, either single phases, such as InSe, In[sub 4]Se[sub 3] or In[sub 2]Se[sub 3], are formed or a mixture of these compounds is present in the film structure. The products are examined by X-ray diffraction, and Raman and IR spectroscopies. The electrochemical properties of lithium-intercalated films are presented. It is observed that the morphology and stoichiometry play an important role in the lithium insertion process. The thermodynamics and kinetics of the insertion reaction are reported. Li/Li[sup +]-borate glass/InSe microbatteries have been built, and their characteristics are reported and discussed using a Butler-Volmer relationship. (orig.)

  15. Airborne plutonium-239 and americium-241 concentrations measured from the 125-meter Hanford Meteorological Tower

    International Nuclear Information System (INIS)

    Airborne plutonium-239 and americium-241 concentrations and fluxes were measured at six heights from 1.9 to 122 m on the Hanford meteorological tower. The data show that plutonium-239 was transported on nonrespirable and small particles at all heights. Airborne americium-241 concentrations on small particles were maximum at the 91 m height

  16. Effect of 241-americium on bone marrow stroma

    International Nuclear Information System (INIS)

    The regulation of haemopoiesis occurs via complex interactions between the stroma and the haemopoietic cells. An attempt to further clarifying the mechanisms and the exact role of the stroma in the regulation was made in a study. Results revealed that the murine bone marrow stromal cells are highly radiosensitive after injection with 241-americium and can thus be considered as a target population after internal contamination. In addition, observations are made which may be important for risk estimation for the developing animal and during pregnancy. Contamination in utero and by lactation shows persistent damage up to 1 year after contamination at an average annual dose of 5 cGy. (author)

  17. Recovery of americium-241 from aged plutonium metal

    International Nuclear Information System (INIS)

    After separation and purification, both actinides were precipitated as oxalates and calcined. A large-scale process was developed using dissolution, separation, purification, precipitation, and calcination. Efforts were made to control corrosion, to avoid product contamination, to keep the volume of process and waste solutions manageable, and to denitrate solutions with formic acid. The Multipurpose Processing Facility (MPPF), designed for recovery of transplutonium isotopes, was used for the first time for the precipitation and calcination of americium. Also, for the first time,, large-scale formic acid denitration was performed in a canyon vessel at SRP

  18. Polystyrene-supported Benzyl Selenide: An Efficient Reagent for Highly Stereocontrolled Synthesis of Substituted Olefins

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Polystyrene-supported benzyl selenide has been prepared. This novel reagent was treated with LDA to produce a selenium stabilized carbanion, which reacted with alkyl halide, followed by selenoxide syn-elimination, to give substituted olefins stereospecificly.

  19. Preferential decorporation of americium by pulmonary administration of DTPA dry powder after inhalation of aged PuO2 containing americium in rats

    International Nuclear Information System (INIS)

    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 diethylenetriaminepentaacetic 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. (authors)

  20. Manipulation of cadmium selenide nanorods with an atomic force microscope

    International Nuclear Information System (INIS)

    We have used an atomic force microscope (AFM) to manipulate and study ligand-capped cadmium selenide nanorods deposited on highly oriented pyrolitic graphite (HOPG). The AFM tip was used to manipulate (i.e., translate and rotate) the nanorods by applying a force perpendicular to the nanorod axis. The manipulation result was shown to depend on the point of impact of the AFM tip with the nanorod and whether the nanorod had been manipulated previously. Forces applied parallel to the nanorod axis, however, did not give rise to manipulation. These results are interpreted by considering the atomic-scale interactions of the HOPG substrate with the organic ligands surrounding the nanorods. The vertical deflection of the cantilever was recorded during manipulation and was combined with a model in order to estimate the value of the horizontal force between the tip and nanorod during manipulation. This horizontal force is estimated to be on the order of a few tens of nN.

  1. Selenide isotope generator for the Galileo mission. Reliability program plan

    International Nuclear Information System (INIS)

    The reliability program plan for the Selenide Isotope Generator (SIG) program is presented. It delineates the specific tasks that will be accomplished by Teledyne Energy Systems and its suppliers during design, development, fabrication and test of deliverable Radioisotopic Thermoelectric Generators (RTG), Electrical Heated Thermoelectric Generators (ETG) and associated Ground Support Equipment (GSE). The Plan is formulated in general accordance with procedures specified in DOE Reliability Engineering Program Requirements Publication No. SNS-2, dated June 17, 1974. The Reliability Program Plan presented herein defines the total reliability effort without further reference to Government Specifications. The reliability tasks to be accomplished are delineated herein and become the basis for contract compliance to the extent specified in the SIG contract Statement of Work

  2. Selenide isotope generator for the Galileo Mission. Program final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-06-01

    This final report for the Selenide Isotope Generator for the Galileo Mission (SIG/GM) documents the work performed by Teledyne Energy Systems (TES) under US Department of Energy (DOE) Contract No. DE-AC01-78ET33009 (formerly ET-78-C-01-2865) during the period April 10, 1978 to June 30, 1979. Because of technical difficulties with the thermoelectric converter being developed by the 3M Company under separate DOE contract, a Stop Work Order, dated January 29, 1979, was issued by DOE. The TES effort up to the receipt of the Stop Work Order as well as limited technical activities up to the contract conclusion on June 30, 1979 are reported.

  3. Hollow Cobalt Selenide Microspheres: Synthesis and Application as Anode Materials for Na-Ion Batteries.

    Science.gov (United States)

    Ko, You Na; Choi, Seung Ho; Kang, Yun Chan

    2016-03-16

    The electrochemical properties of hollow cobalt oxide and cobalt selenide microspheres are studied for the first time as anode materials for Na-ion batteries. Hollow cobalt oxide microspheres prepared by one-pot spray pyrolysis are transformed into hollow cobalt selenide microspheres by a simple selenization process using hydrogen selenide gas. Ultrafine nanocrystals of Co3O4 microspheres are preserved in the cobalt selenide microspheres selenized at 300 °C. The initial discharge capacities for the Co3O4 and cobalt selenide microspheres selenized at 300 and 400 °C are 727, 595, and 586 mA h g(-1), respectively, at a current density of 500 mA g(-1). The discharge capacities after 40 cycles for the same samples are 348, 467, and 251 mA h g(-1), respectively, and their capacity retentions measured from the second cycle onward are 66, 91, and 50%, respectively. The hollow cobalt selenide microspheres have better rate performances than the hollow cobalt oxide microspheres. PMID:26918934

  4. Analytical performance of radiochemical method for americium determination in urine

    International Nuclear Information System (INIS)

    This paper presents an analytical method developed and adapted for separation and analysis of Plutonium (Pu) isotopes and Americium (Am) in urine samples. The proposed method will attend the demand of internal exposure monitoring program for workers involved mainly with dismantling rods and radioactive smoke detectors. In this experimental procedure four steps are involved as preparation of samples, sequential radiochemical separation, preparation of the source for electroplating and quantification by alpha spectrometry. In the first stage of radiochemical separation, plutonium is conventionally isolated employing the anion exchange technique. Americium isolation is achieved sequentially by chromatographic extraction (Tru.spec column) from the load and rinse solutions coming from the anion exchange column. The 243Am tracer is added into the sample as chemical yield monitors and to correct the results improving the precision and accuracy. The mean recovery obtained is 60%, and the detection limit for 24h urine sample is 1.0 mBq L-1 in accordance with the literature. Based in the preliminary results, the method is appropriate to be used in monitoring programme of workers with a potential risk of internal contamination. (author)

  5. Placental transfer of americium and plutonium in mice

    International Nuclear Information System (INIS)

    Actinide element release to the environment and subsequent transfer through food chains to pregnant women may present a radiation hazard to fetuses in utero. To measure americium incorporation, four groups of pregnant mice were intravenously dosed with four concentrations of 243Am citrate in late pregnancy. Concentrations of 243Am in fetuses, placentas, and maternal femur, liver, carcass and pelt were determined 48 hr after injection. Doses were chosen so that the number of atoms of 243Am in each injected dose was equal to the number of atoms of 239Pu used in an earlier study of transplacental movement. Results indicate that, atom for atom, americium is incorporated into fetal tissue in lesser amounts (10-25 times) than is plutonium when intravenously administered to pregnant mice in equal atom amounts. Tissue analyses indicated that, at low dose levels, the average fraction of the dose incorporated into the fetuses decreased as the dose to the pregnant mouse was increased. A similar pattern was noted for placentas and maternal femurs. Data indicate that one must make extrapolations from low dose data only to make reasonable and realistic estimates of the transplacental movement and fetal incorporation of environmental levels of actinide elements in man and other species. (author)

  6. Development of separation techniques of americium from reprocessing solution

    International Nuclear Information System (INIS)

    Americium(Am) and neptunium(Np) finally transfer to the waste stream in the current PUREX reprocessing process. As an option, some methods have been developed to recover Am and Np from the waste stream to decrease long-term toxicity of the high level waste. The most stable valence state of Am is III, but TBP (tri-n-butyl phosphate) which is an extractant used in the PUREX reprocessing does not extract Am(III). Therefore, some special extractants have been developed to recover Am(III). However, they also extract rare-earth elements(REs), which necessitates the separation process for Am from REs. We have been developing a separation process which consists of valence control of Am to the VI state and its extraction with TBP. This process allows Am recovery from reprocessing solution and Am separation from REs simultaneously. Americium(III) is oxidized to Am(VI) by electrochemical oxidation and chemical oxidation using peroxodisulfate ammonium and silver nitrate. The latter was adopted here because the chemical oxidation reaction proceeds faster than the electrochemical method. Reaction mechanisms of oxidation and extraction were investigated. Based on the mechanisms, we found that extraction efficiency could be improved and waste generation could be minimized. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  10. Removal of americium from effluent generated during the purification of plutonium by anion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, Donald M.; Pius, Illipparambil C.; Chaudhury, Satyajeet [Bhabha Atomic Research Centre, Mumbai (India). Fuel Chemistry Div.

    2015-07-01

    Studies have been carried out on removal of americium from the effluent generated during anion exchange purification of plutonium. Americium 241, generated by the beta decay of Plutonium-241, is the major source of a activity in this highly acidic effluent and its removal would render the waste easily disposable. A simple and effective co-precipitation method, using thorium oxalate has been investigated for the treatment of this alpha active aqueous waste. Experiments have been carried out to identify optimum conditions to obtain high percentage co-precipitation with minimum amount of co-precipitant. Efforts were carried out to correlate the optimum conditions of co-precipitation of americium obtained in these experiments with solubility of thorium oxalate and americium oxalate calculated from solubility products of these compounds, stability constants of thorium and americium oxalate complexes taken from literature. The saturation capacity of thorium oxalate for Am(III) was also calculated by analyzing the K{sub d} value data using Langmuir adsorption equation. The strong tendency of americium to get co-precipitated and the high capacity exhibited by thorium oxalate for the uptake of americium indicate feasibility of using this method for the treatment of anion exchange effluent.

  11. Removal of americium from effluent generated during the purification of plutonium by anion exchange

    International Nuclear Information System (INIS)

    Studies have been carried out on removal of americium from the effluent generated during anion exchange purification of plutonium. Americium 241, generated by the beta decay of Plutonium-241, is the major source of a activity in this highly acidic effluent and its removal would render the waste easily disposable. A simple and effective co-precipitation method, using thorium oxalate has been investigated for the treatment of this alpha active aqueous waste. Experiments have been carried out to identify optimum conditions to obtain high percentage co-precipitation with minimum amount of co-precipitant. Efforts were carried out to correlate the optimum conditions of co-precipitation of americium obtained in these experiments with solubility of thorium oxalate and americium oxalate calculated from solubility products of these compounds, stability constants of thorium and americium oxalate complexes taken from literature. The saturation capacity of thorium oxalate for Am(III) was also calculated by analyzing the Kd value data using Langmuir adsorption equation. The strong tendency of americium to get co-precipitated and the high capacity exhibited by thorium oxalate for the uptake of americium indicate feasibility of using this method for the treatment of anion exchange effluent.

  12. Selective leaching studies of deep-sea sediments loaded with americium, neptunium and plutonium

    International Nuclear Information System (INIS)

    A series of selective leaching experiments were undertaken to investigate the solid phase speciation and distribution of americium, neptunium and plutonium which had been experimentally loaded onto different marine sediment types. The chemical leaches employed showed rather poor selectivity but certain trends were evident. Adsorption was not by ion exchange. Americium showed a preferential affinity for carbonate and plutonium for organic matter. Neptunium appeared to have no preferential affinities. Americium was sorbed by acetic acid residues (CaCO3 removed) and by unleached carbonate-rich sediments with equal efficiency. This indicates that it is able to diversify its solid phase affinity/distribution depending upon which solid phases are available. (author)

  13. Solubility of americium collected on an aerosol filter

    International Nuclear Information System (INIS)

    Kinetics of dissolution of undefined americium aerosol in simulated serum ultrafiltrate was studied. 241Am was present in aerosol collected at a workplace, where an intake of 241Am had occurred formerly. Dissolution experiments in four parts of an aerosol filter were carried out either in ambient air or under CO2 and pH was kept within physiological range. Two?phase kinetics was found in both cases with dissolution half?times for rapid and slow phases ranging from 0.16 to 0.23 d and from 150 to 500 d, respectively. Regardless data dispersion, found half?times justify use of class M model in intake assessment. (author)

  14. The 1976 Hanford Americium Accident: Then and Now

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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. PMID:22827724

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

    International Nuclear Information System (INIS)

    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

  17. Pretreatment of americium/curium solutions for vitrification

    International Nuclear Information System (INIS)

    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

  18. Plutonium and americium in sediments of Lithuanian lakes

    International Nuclear Information System (INIS)

    The assessment of contribution of the global and the Chernobyl NPP (Nuclear Power Plant) accident plutonium and americium to plutonium pollution in sediments of Lithuanian lakes is presented. Theoretical evaluation of activity ratios of 238Pu/239+240Pu and 241Pu/239+240Pu in the reactor of unit 4 of the Chernobyl NPP before the accident was performed by means of the ORIGEN-ARP code from the SCALE 4.4A program package. Non-uniform distribution of radionuclides in depositions on the Lithuanian territory after nuclear weapon tests and the Chernobyl NPP accident is experimentally observed by measuring the lake sediment pollution with actinides. The activity concentration of sediments polluted with plutonium ranges from 2.0 ± 0.5 Bq/kg d.w. (dry weight) in Lake Asavelis to 14 ± 2 Bq/kg d.w. in Lake Juodis. The ratio of activity concentrations of plutonium isotopes 238Pu/239+240Pu measured by α-spectrometry in the 10-cm-thick upper layer of bottom sediment varies from 0.03 in Lake Juodis to 0.3 in Lake Zuvintas. The analysis of the ratio values shows that the deposition of the Chernobyl origin plutonium is prevailing in southern and south-western regions of Lithuania. Plutonium of nuclear weapon tests origin in sediments of lakes is observed on the whole territory of Lithuania, and it is especially distinct in central Lithuania. The americium activity due to 241Pu decay after the Chernobyl NPP accident and global depositions in bottom sediments of Lithuanian lakes has been evaluated to be from 0.9 to 5.7 Bq/kg. (author)

  19. Kinetic parameters of transformation of americium and plutonium physicochemical forms in podsol soils

    International Nuclear Information System (INIS)

    Kinetic parameters of transformation of americium and plutonium physicochemical forms have been estimated and the prognosis of fixing and remobilization of these nuclides in podsol soils have been made on that basis in the work. (authors)

  20. Calibration procedures for in vivo sodium iodide spectrometry of plutonium and americium in the human lung

    International Nuclear Information System (INIS)

    This paper describes the calibration techniques and associated error analysis for the in vivo measurement by NaI spectrometry of heavy elements in the lung, specifically plutonium and americium. A very brief description of the instrumentation system is included

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

    Science.gov (United States)

    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.

  2. Structure and photoluminescence of molybdenum selenide nanomaterials grown by hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Plasma Nanoscience Laboratories, Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, P. O. Box 218, Lindfield, NSW 2070 (Australia); Zhu, M.K. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Ostrikov, K., E-mail: kostya.ostrikov@qut.edu.au [Plasma Nanoscience Laboratories, Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, P. O. Box 218, Lindfield, NSW 2070 (Australia); Institute for Future Environments, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia); Shao, R.W.; Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China)

    2015-10-25

    Molybdenum selenide nanomaterials with different structures are synthesized on silicon substrates coated with gold films by hot filament chemical vapor deposition (HFCVD) in nitrogen environment, where molybdenum trioxide and selenium powders are used as source materials. The structure and composition of the synthesized molybdenum selenide nanomaterials are studied using field emission scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The results indicate that the structures of molybdenum selenide change from nanoflakes to nanoparticles with the increase of content of molybdenum trioxide precursor. The photoluminescence (PL) excitation using the 325 nm line of He–Cd laser as the excitation source generates green light with the wavelength of about 512–516 nm. The formation of molybdenum selenide nanomaterials is determined by the decomposition rates of molybdenum trioxide in HFCVD. The possible factors that affect the generation of green PL bands are analyzed. These outcomes of this work enrich our knowledge on the synthesis of transition metal dichalcogenides and contribute to the development of applications of these materials in optoelectronic devices. - Highlights: • Molybdenum selenide nanoflakes, nanoparticles and hybrids produced by HFCVD. • Uncommon MoO{sub 3} and Se precursor co-location and mixing and effective MoO{sub 3} decomposition. • Morphology change from nanoflakes to nanoparticles with higher ratio of MoO{sub 3} precursor. • Strong photoluminescence emission of green light with a wavelength of ∼512–516 nm.

  3. Structure and photoluminescence of molybdenum selenide nanomaterials grown by hot filament chemical vapor deposition

    International Nuclear Information System (INIS)

    Molybdenum selenide nanomaterials with different structures are synthesized on silicon substrates coated with gold films by hot filament chemical vapor deposition (HFCVD) in nitrogen environment, where molybdenum trioxide and selenium powders are used as source materials. The structure and composition of the synthesized molybdenum selenide nanomaterials are studied using field emission scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The results indicate that the structures of molybdenum selenide change from nanoflakes to nanoparticles with the increase of content of molybdenum trioxide precursor. The photoluminescence (PL) excitation using the 325 nm line of He–Cd laser as the excitation source generates green light with the wavelength of about 512–516 nm. The formation of molybdenum selenide nanomaterials is determined by the decomposition rates of molybdenum trioxide in HFCVD. The possible factors that affect the generation of green PL bands are analyzed. These outcomes of this work enrich our knowledge on the synthesis of transition metal dichalcogenides and contribute to the development of applications of these materials in optoelectronic devices. - Highlights: • Molybdenum selenide nanoflakes, nanoparticles and hybrids produced by HFCVD. • Uncommon MoO3 and Se precursor co-location and mixing and effective MoO3 decomposition. • Morphology change from nanoflakes to nanoparticles with higher ratio of MoO3 precursor. • Strong photoluminescence emission of green light with a wavelength of ∼512–516 nm

  4. Using different chemical methods for deposition of copper selenide thin films and comparison of their characterization.

    Science.gov (United States)

    Güzeldir, Betül; Sağlam, Mustafa

    2015-11-01

    Different chemical methods such as Successive Ionic Layer Adsorption and Reaction (SILAR), spin coating and spray pyrolysis methods were used to deposite of copper selenide thin films on the glass substrates. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) spectroscopy and UV-vis spectrophotometry. The XRD and SEM studies showed that all the films exhibit polycrystalline nature and crystallinity of copper selenide thin films prepared with spray pyrolysis greater than spin coating and SILAR methods. From SEM and AFM images, it was observed copper selenide films were uniform on the glass substrates without any visible cracks or pores. The EDX spectra showed that the expected elements exist in the thin films. Optical absorption studies showed that the band gaps of copper selenide thin films were in the range 2.84-2.93 eV depending on different chemical methods. The refractive index (n), optical static and high frequency dielectric constants (ε0, ε∞) values were calculated by using the energy bandgap values for each deposition method. The obtained results from different chemical methods revealed that the spray pyrolysis technique is the best chemical deposition method to fabricate copper selenide thin films. This absolute advantage was lead to play key roles on performance and efficiency electrochromic and photovoltaic devices. PMID:26037495

  5. Magnetic properties of Cr telluride-selenide alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mankovsky, Sergey; Polesya, Svetlana; Ebert, Hubert [Dept. Chemie und Biochemie, Universitaet Muenchen, Butenandtstr. 5-13, D-81377 Muenchen (Germany); Huang, Zhong-Le; Bensch, Wolfgang [Institute for Anorganic Chemistry, Olshausenstr. 40, D-24098, Kiel (Germany)

    2007-07-01

    Results of a theoretical study of the magnetic properties of Cr telluride-selenide alloys having trigonal crystal structure are presented in comparison with experimental results. Both ground state and temperature-dependent magnetic properties of Cr{sub 1-{delta}}Te and Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} (with ratio {alpha}:{beta}=7:1,6:2,5:3) have been investigated in a wide region of chromium content. For the alloys Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} a transition to the state with antiferromagnetic order in a fully occupied sub-lattice and with no order in a partially occupied sub-lattice was obtained. For the alloys Li{sub x}Cr{sub 0.5}Ti{sub 0.75}Se{sub 2}, a non-monotonic dependence of structural and magnetic properties have been found upon increase of Li concentration x, that is in agreement with experimental results. The ground state properties have been studied on the basis of electronic structure calculations using the Korringa-Kohn-Rostoker (KKR) band structure method combined with the CPA alloy theory. Using Monte Carlo simulations we obtained the magnetic configuration at T=0 K and studied the magnetic properties at T>0 K as well. The required exchange coupling parameters were obtained from our ab-initio electronic structure calculations.

  6. A magnetic x-ray diffraction investigation of gadolinium selenide

    Energy Technology Data Exchange (ETDEWEB)

    Costa, M.M.R.; Almeida, M.J.M. de [Departamento de Fisica, Universidade de Coimbra, Coimbra (Portugal); Nuttall, W.J.; Stirling, W.G. [Department of Physics, Keele University, Keele, Staffs (United Kingdom); Tang, C.C. [Daresbury Laboratory, Warrington, Cheshire (United Kingdom); Forsyth, J.B. [Rutherford Appleton Laboratory, Chilton, Oxon (United Kingdom); Cooper, M.J. [Department of Physics, University of Warwick, Coventry (United Kingdom)

    1996-04-01

    A single-crystal synchrotron radiation study of gadolinium selenide has been made in the temperature range 15-100 K. GdSe has the rocksalt structure and becomes antiferromagnetic below a reported Neel temperature of 65 K. At 15 K, magnetic reflections are observed at G+T with modulation wavevector T={l_brace}1/2:1/2:1/2{r_brace} propagating from reciprocal lattice point G. This is achieved by exploiting the resonant enhancement in the vicinity of the Gd L{sub II} and L{sub III} edges. Similar enhancements are observed at the two edges, with the maximum effect occurring approximately 3 eV above the absorption edge. The temperature dependence of the intensity of the magnetic reflections indicates a Neel temperature of 63(1) K. These measurements, together with high-resolution studies of the fundamental reflections (T=0), contribute further evidence of magnetic or structural changes in the sample at 37(1) K. Our observations are discussed and compared with previous x-ray diffraction and magnetic susceptibility measurements. (author)

  7. Distribution of uranium, americium and plutonium in the biomass of freshwater macrophytes

    Energy Technology Data Exchange (ETDEWEB)

    Zotina, T.A.; Kalacheva, G.S.; Bolsunovsky, A.YA. [Institute of Biophysics SB RAS, Akademgorodok, Krasnoyarsk (Russian Federation)

    2010-07-01

    Accumulation of uranium ({sup 238}U), americium ({sup 241}Am) and plutonium ({sup 242}Pu) and their distribution in cell compartments and biochemical components of the biomass of aquatic plants Elodea canadensis, Ceratophyllum demersum, Myrioplyllum spicatum and aquatic moss Fontinalis antipyretica have been investigated in laboratory batch experiments. Isotopes of uranium, americium and plutonium taken up from the water by Elodea canadensis apical shoots were mainly absorbed by cell walls, plasmalemma and organelles. A small portion of isotopes (about 6-13 %) could be dissolved in cytoplasm. The major portion (76-92 %) of americium was bound to cell wall cellulose-like polysaccharides of Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum and Fontinalis antipyretica, 8-23 % of americium activity was registered in the fraction of proteins and carbohydrates, and just a small portion (< 1%) in lipid fraction. The distribution of plutonium in the biomass fraction of Elodea was similar to that of americium. Hence, americium and plutonium had the highest affinity to cellulose-like polysaccharides in Elodea biomass. Distribution of uranium in the biomass of Elodea differed essentially from that of transuranium elements: a considerable portion of uranium was recorded in the fraction of protein and carbohydrates (51 %). From our data we can assume that uranium has higher affinity to carbohydrates than proteins. (authors)

  8. Separation of curium and americium microquantities by chromatographic method with introduction of separating ions. 2. Effect of cadmium ion quantity and method of it introduction in the system on efficiency of curium and americium separation

    International Nuclear Information System (INIS)

    Effect of fractionating cadmium ion and a method of it introduction in the system on efficiency of separation of curium and americium with the use of NTA solutions as an eluent is investigated. It is established that in contrast to mutual sorption of curium, americium and cadmium their selective sorption contributes more complete separation of curium and americium. It is shown that growth of quantity of introduced cadmium increased efficiency of separation. Elution rate not products effect on separation process

  9. Atomic force microscopy study of thermal stability of silver selenide thin films grown on silicon

    International Nuclear Information System (INIS)

    Silver selenide thin films were grown on silicon substrates by the solid-state reaction of sequentially deposited Se and Ag films of suitable thickness. Transmission electron microscopy and particle-induced X-ray emission studies of the as-deposited films showed the formation of single phase polycrystalline silver selenide from the reaction of Ag and Se films. Atomic force microscopy images of the as-deposited and films annealed at different temperatures in argon showed the film morphology to evolve into an agglomerated state with annealing temperature. The results indicate that when annealed above 473 K, silver selenide films on silicon become unstable and agglomerate through holes generated at grain boundaries

  10. Two-dimensional tin selenide nanostructures for flexible all-solid-state supercapacitors.

    Science.gov (United States)

    Zhang, Chunli; Yin, Huanhuan; Han, Min; Dai, Zhihui; Pang, Huan; Zheng, Yulin; Lan, Ya-Qian; Bao, Jianchun; Zhu, Jianmin

    2014-04-22

    Due to their unique electronic and optoelectronic properties, tin selenide nanostructures show great promise for applications in energy storage and photovoltaic devices. Despite the great progress that has been achieved, the phase-controlled synthesis of two-dimensional (2D) tin selenide nanostructures remains a challenge, and their use in supercapacitors has not been explored. In this paper, 2D tin selenide nanostructures, including pure SnSe2 nanodisks (NDs), mixed-phase SnSe-SnSe2 NDs, and pure SnSe nanosheets (NSs), have been synthesized by reacting SnCl2 and trioctylphosphine (TOP)-Se with borane-tert-butylamine complex (BTBC) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone. Utilizing the interplay of TOP and BTBC and changing only the amount of BTBC, the phase-controlled synthesis of 2D tin selenide nanostructures is realized for the first time. Phase-dependent pseudocapacitive behavior is observed for the resulting 2D nanostructures. The specific capacitances of pure SnSe2 NDs (168 F g(-1)) and SnSe NSs (228 F g(-1)) are much higher than those of other reported materials (e.g., graphene-Mn3O4 nanorods and TiN mesoporous spheres); thus, these tin selenide materials were used to fabricate flexible, all-solid-state supercapacitors. Devices fabricated with these two tin selenide materials exhibited high areal capacitances, good cycling stabilities, excellent flexibilities, and desirable mechanical stabilities, which were comparable to or better than those reported recently for other solid-state devices based on graphene and 3D GeSe2 nanostructures. Additionally, the rate capability of the SnSe2 NDs device was much better than that of the SnSe NS device, indicating that SnSe2 NDs are promising active materials for use in high-performance, flexible, all-solid-state supercapacitors. PMID:24601530

  11. Effect of He+ irradiation on the optical properties of vacuum evaporated silver indium selenide thin films

    International Nuclear Information System (INIS)

    We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The samples were subjected to the irradiation of 1.26 M eV He+ ion. The effect of irradiation on the optical properties has been investigated for different fluencies of He+. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. It is observed that the band gap of silver indium selenide thin films decreases gradually from 1.17 to 0.82 eV with ion fluency.

  12. Spray pyrolysis deposited tin selenide thin films for thermoelectric applications

    International Nuclear Information System (INIS)

    Tin selenide thin films were prepared by spray pyrolysis technique using tin (II) chloride and selenourea as a precursor compounds using Se:Sn atomic ratio of 1:1 in the starting solution onto glass substrates. Deposition process was carried out in the substrate temperature range of 250 °C–400 °C using 1 ml/min flow rate. The films were investigated using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, optical absorption and thermoelectric studies. The X-ray diffraction patterns suggest that the major phase is hexagonal-SnSe2 was present when the deposition was carried out in 275–375 °C temperature range, while for the films deposited in the below and above to this range, Sn and Se precipitates into some impure and mixed phase. Raman scattering analysis allowed the assignment of peaks at ∼180 cm−1 to the hexagonal-SnSe2 phase. The optical absorption study shows that the direct band gap of the film decreases with increase in substrate temperature and increasing crystallite size. The thermo-electrical measurements have shown n-type conductivity in as deposited films and the magnitude of thermo EMF for films has been found to be increasing with increasing deposition temperature, except for 350 °C sample. 350 °C deposited samples shows enhance thermoelectric value as compared to other samples. Thermoelectric study reveal that although sample deposited between 275 °C and 375 °C are structurally same but 350 °C sample is thermoelectrically best. - Highlights: • Influence of substrate temperature on the deposition of SnSe has been shown. • Seebeck measurements at 275°C–375 °C confirms n-type conductivity. • Higher seebeck coefficient has been observed at 350 °C deposited film. • Decrease in band gap was observed on increasing Tsub and size of the crystallites

  13. Photoconductivity in reactively evaporated copper indium selenide thin films

    International Nuclear Information System (INIS)

    Copper indium selenide thin films of composition CuInSe2 with thickness of the order of 130 nm are deposited on glass substrate at a temperature of 423 ±5 K and pressure of 10−5 mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%), Indium (99.999%) and Selenium (99.99%) as the elemental starting materials. X-ray diffraction (XRD) studies shows that the films are polycrystalline in nature having preferred orientation of grains along the (112) plane. The structural type of the film is found to be tetragonal with particle size of the order of 32 nm. The structural parameters such as lattice constant, particle size, dislocation density, number of crystallites per unit area and strain in the film are also evaluated. The surface morphology of CuInSe2 films are studied using 2D and 3D atomic force microscopy to estimate the grain size and surface roughness respectively. Analysis of the absorption spectrum of the film recorded using UV-Vis-NIR Spectrophotometer in the wavelength range from 2500 nm to cutoff revealed that the film possess a direct allowed transition with a band gap of 1.05 eV and a high value of absorption coefficient (α) of 106 cm−1 at 570 nm. Photoconductivity at room temperature is measured after illuminating the film with an FSH lamp (82 V, 300 W). Optical absorption studies in conjunction with the good photoconductivity of the prepared p-type CuInSe2 thin films indicate its suitability in photovoltaic applications

  14. Americium(3) solvent extraction by oxides of dialkyl(diaryl)[dialkylcarbamoylmethyl]phosphines (CMPO) from perchloric acid solutions

    International Nuclear Information System (INIS)

    Extraction of americium(3) from perchloric acid solutions by CMPO was investigated. It is shown that americium(3) is much more effectively extracted from perchloric acid solutions, than from nitric acid ones, and increase in americium distribution coefficient depends considerably on reagent nature. As a consequence, anomalous aryl effect increases significantly in perchloric acid solutions. The value of anomalous aryl effect depends directly on stoichiometry of extracted complexes in nitric acid and perchloric acid media. Conditions for extractional concentration of americium up to the 100-fold one with small reagent consumption were suggested

  15. Extraction of Americium(III) by diglycolamides in ionic liquids

    International Nuclear Information System (INIS)

    In the present work, the extraction behavior of Am(lII) in the three isomeric DGAs, TODGA, DEHDODGA and TEHDGA in two ionic liquids, 1-butyl-3-methylimidazolium bis(triflouromethane sulphonyl)imide (C4mimNTf2) and 1-butyl-1-methylpyrrolidinium bis(triflouromethanesulphonyl)imide (C4mpyNTf2) is compared. The distribution ratio of americium was determined at various acidities ranging from 1M to 8M. The distribution values were found to decrease with increase in aqueous phase acidity upto 3M. The DAm values then marginally increased with increase of acidity from 3 to 4M followed by a decrease in distribution values. The distribution ratio obtained for various DGAs followed the order TEHDGA < TODGA < DEHDODGA at aqueous phase acidities ranging from 1-4 M. When the aqueous nitric acid concentration was higher than 4M, the distribution values followed the order DEHDODGA < TEHDGA < TODGA. The anomalous behaviour of unsymmetrical diglycolamide in ionic liquid medium was investigated by IR spectroscopy. The study revealed that the unprotonated fraction of DGA (i.e. the free DGA) increased in the order TEHDGA < TODGA < DEHDODGA, which seems to be responsible for the observed anomalous extraction trend in DEHDODGA in ionic liquid medium

  16. Extraction of americium and europium by CMPO-substituted adamantylcalixarenes

    International Nuclear Information System (INIS)

    Eight p-adamantylcalix[4]arene derivatives, bearing four CMPO-like functions [-(CH2)n-NH-C(O)-CH2-P(O)Ph2] at the wide (4a,b, n = 0, 1) or narrow (5a-c and 6a-c, n = 2-4) rims were synthesized for the first time. Studies of the extraction of americium(III) and europium(III) from 3 M HNO3 solutions to organic phases (dichloromethane, m-nitro-trifluoromethylbenzene) showed: (i) The extraction ability for all the adamantylcalixarene ligands is much better than for their monomeric analogues -N-(1-adamantyl)-, N-(1-adamantylmethyl)- and N,N-(dibutyl)carbamoylmethyldiphenylphosphine oxides 7a, 7b, 8; (ii) The extraction percentage increases strongly with increasing length of the spacer for all types of ligands 4-6, and best extraction results were found for 4b (n = 1) and 5c (n = 4); (iii) The separation coefficient DAm/DEu for the investigated compounds did not exceed 2, which is close to the narrow rim CMPO calixarenes, studied earlier; (iv) Variation of the spacer length between CMPO groups attached to the 1,3- and 2,4-positions of the calixarene platform in 6 did not lead to appreciably improved extractants, neither with respect to the extraction abilities (D) nor to the selectivities (DAm/DEu). (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrova, M., E-mail: maka-alexandrova@rambler.r [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Rozhko, T. [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Vydryakova, G. [Institute of Biophysics SB RAS, Akademgorodok 50, 660036 Krasnoyarsk (Russian Federation); Kudryasheva, N. [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Institute of Biophysics SB RAS, Akademgorodok 50, 660036 Krasnoyarsk (Russian Federation)

    2011-04-15

    The effect of americium-241 ({sup 241}Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of {sup 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 {sup o}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 {sup 241}Am is discussed. The effect of {sup 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 {sup 241}Am solutions was demonstrated; and the similarity of {sup 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. - Highlights: {yields} Am-241 in water solutions (A = 0.16-6.7 kBq/L) suppresses bacterial growth.{yields} Am-241 (A = 0.16-6.7 kBq/L) stimulate bacterial luminescence. {yields} Peroxides, secondary radiolysis products, cause increase of bacterial luminescence.

  18. Polystyrene-supported Selenides and Selenoxide:Versatile Routes to Synthesize Allylic Alcohols

    Institute of Scientific and Technical Information of China (English)

    Wei Ming XU; You Chu ZHANG; Xian HUANG

    2003-01-01

    Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, followed by selenoxide syn-elimination and [2,3] sigmatropic rearrangement respectively to give Z-allylic alcohols stereoselectively.

  19. Effect of sulfur doping on thermoelectric properties of tin selenide – A first principles study

    International Nuclear Information System (INIS)

    In this work we present the thermoelectric properties of tin selenide (SnSe) and sulfur doped tin selenide(SnSe(1-x)Sx, x= 0.125 and 0.25) obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BOLTZTRAP code using the constant relaxation time approximation at three different temperatures 300, 600 and 800 K. Seebeck coefficient (S) was found to decrease with increasing temperature, electrical conductivity (σ/τ) was almost constant in the entire temperature range and thermal conductivity (κ/τ) increased with increasing temperature for all samples. Sulfur doped samples showed enhanced seebeck coefficient, decreased thermal conductivity and decreased electrical conductivity at all temperatures. At 300 K, S increased from 1500 µV/K(SnSe) to 1720μV/K(SnSe0.75S0.25), thermal conductivity decreased from 5 × 1015 W/mKs(SnSe) to 3 × 1015 W/mKs(SnSe0.75S0.25), electrical conductivity decreased from 7 × 1020/Ωms(SnSe) to 5 × 1020 /Ωms(SnSe0.75S0.25). These calculations show that sulfur doped tin selenide exhibit better thermoelectric properties than undoped tin selenide

  20. Formation of Silver Selenide Layers on Polyamide 6 Films by the Use of Potassium Selenotrithionate

    Directory of Open Access Journals (Sweden)

    Remigijus IVANAUSKAS

    2011-11-01

    Full Text Available A polyamide 6 films if treated with the potassium selenotrithionate, K2SeS2O6, solution in hydrochloric acid, absorbs selenium the form of selenotrithionate anion, SeS2O62-, and the anions decompose in polymer with time. Further interaction of selenized PA films with AgNO3 solution (10 min, 80 °C leads to the formation of silver selenide layers on the polymer surface. The mechanism of formation of silver selenide layers on PA 6 films was proposed. The chemical analyzes show that the concentrations of silver and selenium in polyamide 6 film increase when increase the duration of polymer seleniumization. The molar ratio of Ag/Se in the layers of silver selenide on polyamide films varied from 0.57 : 1 to 0.7 : 1. The X-ray diffraction analysis confirmed the formation of silver selenide layers with elemental selenium in the surface of polyamide 6. The phases of orthorhombic naumannite - Ag2Se (24-1041 and monoclinic selenium - Se8 (71-528 were identified in the formed layers.http://dx.doi.org/10.5755/j01.ms.17.4.775

  1. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    International Nuclear Information System (INIS)

    Highlights: ► Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ► The fabricated white LEDs show good white balance. ► CdSe QDs present well green to yellow band luminescence. ► CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de l’Éclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors

  2. The bulk modulus of cubic spinel selenides: an experimental and theoretical study

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, Leif; Olsen, J.S.;

    2009-01-01

    It is argued that mainly the selenium sublattice determines the overall compressibility of the cubic spinel selenides, AB2Se4, and that the bulk modulus for these compounds is about 100GPa. The hypothesis is supported by experiments using high-pressure X-ray diffraction and synchrotron radiation...

  3. Spray pyrolysis deposited tin selenide thin films for thermoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Anwar, Sharmistha; Gowthamaraju, S.; Mishra, B.K.; Singh, S.K.; Shahid, Anwar, E-mail: shahidanwr@gmail.com

    2015-03-01

    Tin selenide thin films were prepared by spray pyrolysis technique using tin (II) chloride and selenourea as a precursor compounds using Se:Sn atomic ratio of 1:1 in the starting solution onto glass substrates. Deposition process was carried out in the substrate temperature range of 250 °C–400 °C using 1 ml/min flow rate. The films were investigated using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, optical absorption and thermoelectric studies. The X-ray diffraction patterns suggest that the major phase is hexagonal-SnSe{sub 2} was present when the deposition was carried out in 275–375 °C temperature range, while for the films deposited in the below and above to this range, Sn and Se precipitates into some impure and mixed phase. Raman scattering analysis allowed the assignment of peaks at ∼180 cm{sup −1} to the hexagonal-SnSe{sub 2} phase. The optical absorption study shows that the direct band gap of the film decreases with increase in substrate temperature and increasing crystallite size. The thermo-electrical measurements have shown n-type conductivity in as deposited films and the magnitude of thermo EMF for films has been found to be increasing with increasing deposition temperature, except for 350 °C sample. 350 °C deposited samples shows enhance thermoelectric value as compared to other samples. Thermoelectric study reveal that although sample deposited between 275 °C and 375 °C are structurally same but 350 °C sample is thermoelectrically best. - Highlights: • Influence of substrate temperature on the deposition of SnSe has been shown. • Seebeck measurements at 275°C–375 °C confirms n-type conductivity. • Higher seebeck coefficient has been observed at 350 °C deposited film. • Decrease in band gap was observed on increasing Tsub and size of the crystallites.

  4. Formation of Cadmium Selenide Layers on the Polyamide Film Surface by Sorption-Diffusion Method

    Directory of Open Access Journals (Sweden)

    Neringa Petrašauskienė

    2015-03-01

    Full Text Available The layers containing cadmium selenide, CdxSe,were formed on the surface of semihydrophilic polymer – polyamide 6 (PA using acidified 0.10 mol/dm3 solution of potassium selenotrithionate, K2SeS2O6,as precursor of selenium. The concentration of sorbed selenium (at 60 oC increases with the increase of the duration of PA treatment in K2SeS2O6solution. The cadmium selenide containing layers are formed on the surface of PA after the treatment of seleniumized polymer with cadmium acetate, (Cd(CH3COO2·2H2O, solution (60–80 oC:the anions SeS2O62– containing selenium atoms of low oxidation state react with the cadmium(II ions. The conditions of a polymer initial seleniumization and of seleniumized PA treatment with cadmium acetate solution determine the concentration of cadmium and the composition of chalcogenide layer. The concentration of cadmium in the chalcogenide layer increases with the increase of initial chalcogenization duration only up to about 2 h and the temperature of selenotrithionate solution. The results of XPS and XRD confirmed the formation of cadmium selenide layers on the surface of PA. XRD patterns study of not earlier studied CdSe layers on PA showed their phase composition of two cadmium selenides phases – Zinc blende (cubic CdSe,wurtzite (hexagonal CdSe and cadmium(II hydroxide, Cd(OH2. Accordingly data of XRD and XPS analysis the macrostructure and composition ofCuSe layers depends on the conditions of these layers formation. The data determined enable formation of the layers of cadmium selenide on the surface of PA by thesorption-diffusion method using the solution of potassium selenotrithionate as a precursor of selenium.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5097

  5. Separation and determination of americium in low-level alkaline waste of NPP origin

    Science.gov (United States)

    Todorov, B.; Djingova, R.; Nikiforova, A.

    2006-01-01

    The aim of this work is to develop a short and cost-saving procedure for the determination of 241Am in sludge sample of the alkaline low-level radioactive waste (LL LRAW) collected from Nuclear Power Plant “Kozloduy”. The determination of americium was a part of a complex analytical approach, where group actinide separation was achieved. An anion exchange was used for separation of americium from uranium, plutonium and iron. For the separation of americium extraction with diethylhexyl phosphoric acid (DEHPA) was studied. The final radioactive samples were prepared by micro co-precipitation with NdF3, counted by alpha and gamma spectrometry. The procedure takes 2 hours. The recovery yield of the procedure amounts to (95 ± 1.5)% and the detection limit is 53 mBq/kg 241Am (t=150 000 s). The analytical procedure was applied for actual liquid wastes and results were compared to standard procedure.

  6. Americium 241 in vegetation of natural biocenoses and agrocenoses on Belarus territories contaminated with Chernobyl fall-out

    International Nuclear Information System (INIS)

    As a result of beta-decay of plutonium 241 the content of americium 241 increases progressively in soils, contaminated with Chernobyl trans uranium elements. Americium 241 displayed higher (0,5 - 1,5-fold) biological mobility than isotopes of plutonium 239, 240. Activity of americium 241 in surface phyto mass of wild and cultural plants varies from 0,04 to 5,9 Bq/kg of dry weight. Americium 241 contribution to the total trans uranium elements contamination of plants made up 60 - 80% in 1996 - 1998. Investigation of trials from the areas adjacent to the 30-km zone showed that mobility of americium 241 and plutonium was 5 - 15 times as high as in the zone

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

    International Nuclear Information System (INIS)

    The biodistribution of plutonium and americium has been studied in a rat model after inhalation of two PuO2 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 PuO2 with a higher proportion of americium shows an accelerated transfer of activity from lungs to blood as compared to PuO2 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 PuO2 powders with a higher dissolution rate for both plutonium and americium being obtained for the PuO2 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 PuO2 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. (authors)

  8. Determination of trace concentration of uranium in americium oxide samples by ICP-AES

    International Nuclear Information System (INIS)

    A solvent extraction method has been developed for the determination of uranium (200-2000 ppm) in americium oxide samples. The method involves the quantitative separation of uranium from americium matrix using mixed solvent comprising 1.1M tri-n-butyl phosphate (TBP) +1% trialkyl phosphine oxide (TRPO) + 0.3 M tertiary butyl hydroquinone (TBHQ) in n-dodecane. Uranium from the organic is stripped into the aqueous phase with 0.8 M oxalic acid and determined by ICP-AES. The reliability of the method was ascertained by analytical recovery, which is found to be nearly 100%. (author)

  9. Adsorption-desorption characteristics of plutonium and americium with sediment particles in the estuarine environment: studies using plutonium-237 and americium-241

    International Nuclear Information System (INIS)

    The particle formation of plutonium and americium, their adsorption onto fresh water sediments and the desorption from the sediments in sea water were studied in the Laboratory under simulated river-estuary conditions, using γ-emitting plutonium-237 and americium-241. The results of the experiments show that the particle formation of plutonium depends on its valence states, on pH and on the salinity of the medium. For river water at pH4, some 25%, 20% and 30% of the added 237Pu was in particulate form, larger than 0.45 μm, for Pu (III), Pu (IV) and Pu (VI), respectively, while 65%, 90% and 50% of the respective valence states was associated with particles at pH 8. In sea water the general pattern remains similar, although Pu (VI) is more soluble in sea water owing to higher ligand concentrations for carbonate and bicarbonate complexes. The pH-dependency of particle formation of Am (III) is more steep than that of plutonium and seems to be influenced by colloidal substances occurring in the experimental media. The adsorption-desorption characteristics of plutonium and americium with the sediment in river water as well as sea water reflect the characteristics of their particle formation, being dependent upon such properties as valence states, the pH and salinity of the medium. A sewage effluent added to the media has small but measurable effects on the adsorption-desorption processes of plutonium. (author)

  10. Impact of ionic liquids on europium and americium extraction by an upper rim phosphorylated calixarene

    International Nuclear Information System (INIS)

    The solvent extraction of europium and americium using the calixarene 5,11,17,23-tetrakis[dipropylphosphinylmethyl] 25,26,27,28-tetrapropoxycalix[4]arene (conical conformation) in the presence of ionic liquids with different natures was studied. It was shown that upper rim phosphorylated calixarene is able to extract europium and americium from nitric acid to dichloroethane by forming a 1:1 complex without the addition of ionic liquids. The distribution coefficients of americium are higher than those of europium in this case, but the isolation degrees of both elements are insufficient for this system to be useful in extraction technologies. The addition of the ionic liquid trihexyl(tetradecyl)phosphonium hexafluorophosphate increases the europium distribution coefficient by values ranging from twofold to more than two orders of magnitude at ionic liquid concentrations of 1 and 50 %, respectively. The values of the distribution coefficients for americium are increased by approximately 25-fold after a 50 % addition of the ionic liquid. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Speciation and bioavailability of plutonium and americium in the Irish Sea and other marine ecosystems

    International Nuclear Information System (INIS)

    Since the late 1960s, the Irish Sea has become a repository for a variety of radio-elements originating mainly in discharges from the British Nuclear Fuels (BNF) plc. Sellafield reprocessing complex located on the Cumbrian coast. In particular, transuranium nuclides such as plutonium, americium and curium (the main constituents of the α-emitting discharges) have become incorporated into every marine compartment by a variety of mechanisms, many of which are not well understood. Although extensive studies have been carried out in the near-field (eastern Irish Sea, especially in the vicinity of the discharge point and collateral muddy sediments), comparatively little had been done to assess the long-term behaviour and bioavailability of plutonium and americium in the far-field, e.g., the western Irish Sea, prior to the present study. In this dissertation, the results of an extensive research programme, undertaken in order to improve and refine our understanding of the behaviour of plutonium and americium in the marine environment, are presented. Specifically, the thesis details the results of (and conclusions deduced from) a series of experiments in which the physical and chemical speciation, colloidal association, mobility and bioavailability of plutonium and americium were examined in diverse environments including the Irish Sea and the Mediterranean. (author)

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    extractions. The degree of readsorption in dynamic and conventional batch extraction systems are 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...

  14. Extraction chromatographic recovery of americium from acidic raffinate solutions using CMPO adsorbed on Chromosorb-102

    International Nuclear Information System (INIS)

    Microgram amounts of americium have been separated and purified from large amounts of uranium present in effluent solutions resulting from the anion-exchange columns during the purification and recovery of plutonium by using TBP extraction followed by extraction chromatography using CMPO adsorbed on Chromosorb-102. (author). 4 refs., 1 tab

  15. Cesium-137 and americium-241 distribution by granulometric fractions of soil at Azgir test site grounds

    International Nuclear Information System (INIS)

    In measurements of radionuclide specific content in surface soil layer of contaminated territories it is important to determine in what agglomerations of soil particles there is the highest radionuclide concentration. For this purpose granulometric composition of soil at Azgir test site was studied and cesium-137 and americium-241 distribution by soil fractions was researched. (author)

  16. Development of analytical methods for the separation of plutonium, americium, curium and neptunium from environmental samples

    OpenAIRE

    Salminen, Susanna

    2009-01-01

    In this work, separation methods have been developed for the analysis of anthropogenic transuranium elements plutonium, americium, curium and neptunium from environmental samples contaminated by global nuclear weapons testing and the Chernobyl accident. The analytical methods utilized in this study are based on extraction chromatography. Highly varying atmospheric plutonium isotope concentrations and activity ratios were found at both Kurchatov (Kazakhstan), near the former Semipalatinsk...

  17. Determination of specific activity of americium and plutonium in selected environmental samples

    International Nuclear Information System (INIS)

    The aim of this work was development of method for determination of americium and plutonium in environmental samples. Developed method was evaluated on soil samples and after they was applied on selected samples of fishes (smoked mackerel, herring and fillet from Alaska hake). The method for separation of americium is based on liquid separation with Aliquate-336, precipitation with oxalic acid and using of chromatographic material TRU-SpecTM.The intervals of radiochemical yields were from 13.0% to 80.9% for plutonium-236 and from 10.5% to 100% for americium-241. Determined specific activities of plutonium-239,240 were from (2.3 ± 1.4) mBq/kg to (82 ± 29) mBq/kg, the specific activities of plutonium-238 were from (14.2 ± 3.7) mBq/kg to (708 ± 86) mBq/kg. The specific activities of americium-241 were from (1.4 ± 0.9) mBq/kg to (3360 ± 210) mBq/kg. The fishes from Baltic Sea as well as from North Sea show highest specific activities then fresh-water fishes from Slovakia. Therefore the monitoring of alpha radionuclides in foods imported from territories with nuclear testing is recommended

  18. Application of hollow fiber supported liquid membrane for the separation of americium from the analytical waste

    International Nuclear Information System (INIS)

    Americium from analytical solid waste containing U and metallic impurities was separated using hollow fiber supported liquid membrane (HFSLM) technique impregnated with DHOA-TODGA from nitric acid medium. An aliquot of 5 g of the solid waste containing Am (19.95 mg) as minor actinide and of U (2,588 mg), Fe (1,360 mg), Ca (1,810 mg) and Na (3,130 mg) as major impurities was processed. The feed solution obtained after the dissolution of the residue in ∼4 M HNO3 was passed through HFSLM module. In the first stage using 1 M DHOA-dodecane was used for the separation of Am from other impurities. Though, majority of the elements were separated in this cycle, Ca was co extracted along with the americium. CMPO extraction chromatographic technique was used for further separation of americium from Ca. Significant decontamination factors were achieved in this three step separation process with respect to U, Fe, Na and Ca with ∼77 % recovery of americium. (author)

  19. Determination of α-emitters (plutonium, americium, curium ...) in feces and urine ashes

    International Nuclear Information System (INIS)

    A description is given of the methods used to determine a number of radionuclides to be found in feces and urine, and obtain samples thin enough for counting and α-spectrometry. These methods can be applied to plutonium, americium and curium especially

  20. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    International Nuclear Information System (INIS)

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2-xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells

  1. Functional metal sulfides and selenides for the removal of hazardous dyes from Water.

    Science.gov (United States)

    Shamraiz, Umair; Hussain, Raja Azadar; Badshah, Amin; Raza, Bareera; Saba, Sonia

    2016-06-01

    Water contamination by organic dyes, is among the most alarming threats to healthy green environment. Complete removal of organic dyes is necessary to make water healthy for drinking, cooking, and for other useful aspects. Recently use of nanotechnology for removing organic dyes, became fruitful because of high surface to volume ratio and adsorption properties. Among these materials, metal chalcogenides emerge as new class of active materials for water purification. In this review article, we gathered information related to sulfide and selenide based nanomaterials which include metal sulfides and selenides, their binary composites, and use of different capping agents and dopants for enhancing photocatalysis. We have discussed in detail, about adsorption power of different dyes, relative percentage degradation, reaction time and concentration. PMID:27010842

  2. Upper Limits to Americium Concentration in Medium Size Sodium Cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.P.; Wallenius, J. [Royal Institute of Technology (KTH), AlbaNova University Centre, S-106 91, Stockholm (Sweden)

    2009-06-15

    The fastest way to realize transmutation of minor actinides would be using existing reactor types, adding some proper modifications to allow for insertion of MA in the fuel. According to calculations by Fazio and co-workers, the consumption rate of TRU in a low conversion ratio fast reactor may reach 70-75 % of that of an ADS with uranium free fuel [1]. However, americium introduction brings a negative influence on several safety parameters such as {beta}{sub eff}, Doppler coefficient, coolant temperature coefficient and void worth. Therefore the upper limit of americium that can be included into the fuel needs to be carefully evaluated. In this paper, fast reactor fuels with various minor actinide fractions are loaded into a SAS4A model of the semi-commercial BN600 reactor. Unprotected loss of flow (ULOF) and transient over power (UTOP) accidents are modelled using safety parameters obtained from Monte Carlo simulations as well as from the deterministic calculations published by Fazio et al. Applying the latter parameters (obtained with VARI3D), the upper limit to MA concentration in the fuel of a medium sized SFR of BN-600 type appears at 12%, corresponding to 8% of americium. We note however that the Doppler constants displayed by Fazio et al for MA concentrations above 10% have a considerably larger magnitude than those obtained with MCNP. Applying the safety parameters obtained with Monte Carlo simulations and updated nuclear data evaluations, we find that the upper limit to the americium concentration allowing to survive a ULOF is about half of that inferred by the use of parameters from VARI-3D. Since such a difference has a major impact on the predicted americium transmutation capability of SFR, it is of high priority to analyse the reasons for the apparent discrepancies. We note here that the major contribution to the Doppler feedback comes from capture resonance in U-238 and Pu-240 residing below the sodium scattering resonance located at 3 keV, and that

  3. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    OpenAIRE

    Rodriguez-Torres, Marcos R.; Velez, Christian; Zayas, Beatriz; Rivera, Osvaldo; Arslan, Zikri; Gonzalez-Vega, Maxine N.; Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo; Primera-Pedrozo, Oliva M.

    2015-01-01

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, ...

  4. Enhancement of thermoelectric figure-of-merit by resonant states of aluminium doping in lead selenide

    OpenAIRE

    Zhang, Qinyong; Wang, Hui; Liu, Weishu; Wang, Hengzhi; Yu, Bo; Zhang, Qian; Tian, Zhiting; Lee, Sangyeop; Esfarjani, Keivan; Chen, Gang; Ren, Zhifeng; Ni, George Wei

    2011-01-01

    By adding aluminium (Al) into lead selenide (PbSe), we successfully prepared n-type PbSe thermoelectric materials with a figure-of-merit (ZT) of 1.3 at 850 K. Such a high ZT is achieved by a combination of high Seebeck coefficient caused by very possibly the resonant states in the conduction band created by Al dopant and low thermal conductivity from nanosized phonon scattering centers.

  5. Lattice Dynamics at Zone-Center of Sulphide and Selenide Spinels

    Institute of Scientific and Technical Information of China (English)

    A.K. Kushwaha

    2008-01-01

    A rigid-ion model is used to calculate the force constants and effective dynamical charges of sulphide and selenide spinels. The Raman and infrared phonon modes of normal cubic sulphide spinels MCr2S4 (M=Mn, Co, Fe, Hg, Zn, and Cd) and selenide spinels MCr2Se4 (M=Hg, Zn, and Cd) are calculated at the first Brillouin zone-centre using above model. The significant outcome of the present work is (I) the interatomic interaction between Cr-S (Se) dominates over the Cr-S(Se) and S-S(Se-Se) type of interatomic interactions, (ii) the effective dynamical charges of the bivalent metal ions are nearly zero, and (ⅲ) the selenide spinels are less ionic than the sulphide spinels and the ionicity decreases as MnCr2S4 FeCr2S4 CoCr2S4 > and CdCr2C4 > ZnCr2C4 > HgCr2C4 (C=S and Se). The zone-center phonon frequencies, calculated using these parameters, are found to be in very good agreement with the observed results.

  6. Effect of bone-status on retention and distribution of americium-241 in bones of small rodents

    International Nuclear Information System (INIS)

    Forced physical exercise before and after application of americium-241 resulted in only small changes in bone-structure and behaviour of the radionuclide in bone. Feeding of a low phosphorus or low calcium diet resulted in an increased excretion of americium from bone, whereby Zn-DTPA as chelating agent removed an additional fraction of the radionuclide from bone. Low calcium diet and simultaneous continuous infusion of pharmacological doses of vitamin D-hormones didn't increase the excretion of americium more than the low calcium diet alone. (orig.)

  7. Interaction and diffusion transport of americium in soils

    International Nuclear Information System (INIS)

    The final disposal of High Level Radioactive Wastes (HLRW) is based on its long-term storage in underground facilities located in geological stable sites with a multi-barrier system, the so called Deep Geological Repositories (DGR), that will keep HLRW confined for >10.000 years. After this period of time, leachates rich in long-live radioisotopes might escape from DGR and start to transport towards the biosphere. There is still a lack of information concerning the interaction and transport in soils of some radionuclides present in HLRW, especially for radionuclides that present a high sorption, such as americium (Am). Having reliable information about the mobility of radionuclides in soils is crucial in order to develop risk assessment models and to take proper decisions in case of soil contamination. The aim of the present work was, by means of laboratory scale experiments, to study the interaction and, for first time, to evaluate the diffusion transport of 241Am in soils. The 241Am interaction in soils was assessed by applying sorption batch assays to 20 soil samples with contrasted edaphic properties which allowed us to quantify the solid-liquid distribution coefficient (Kd) and desorption percentage. Kd (Am) values ranged from 103 to 105 L kg-1 and desorption percentages were always less than 2% which denoted a high capacity of the soil to incorporate the Am and a low reversibility of the sorption process. The influence of soil properties in 241Am interaction was studied by means of multiple linear and multivariate regressions. Although a single correlation between Kd (Am) values and a soil property was not found, the main properties affecting 241Am interaction in soils were soil pH, carbonate and organic matter contents in the soil. Finally, additional batch assays at different controlled pH were done to study Am sorption as a function of the contact solution pH. A variation of the Am sorption capacity was observed in all soils due to the dissolution of soil

  8. Interaction and diffusion transport of americium in soils

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Marti i Franques 1-11, 08028, Barcelona (Spain)

    2014-07-01

    The final disposal of High Level Radioactive Wastes (HLRW) is based on its long-term storage in underground facilities located in geological stable sites with a multi-barrier system, the so called Deep Geological Repositories (DGR), that will keep HLRW confined for >10.000 years. After this period of time, leachates rich in long-live radioisotopes might escape from DGR and start to transport towards the biosphere. There is still a lack of information concerning the interaction and transport in soils of some radionuclides present in HLRW, especially for radionuclides that present a high sorption, such as americium (Am). Having reliable information about the mobility of radionuclides in soils is crucial in order to develop risk assessment models and to take proper decisions in case of soil contamination. The aim of the present work was, by means of laboratory scale experiments, to study the interaction and, for first time, to evaluate the diffusion transport of {sup 241}Am in soils. The {sup 241}Am interaction in soils was assessed by applying sorption batch assays to 20 soil samples with contrasted edaphic properties which allowed us to quantify the solid-liquid distribution coefficient (K{sub d}) and desorption percentage. K{sub d} (Am) values ranged from 10{sup 3} to 10{sup 5} L kg{sup -1} and desorption percentages were always less than 2% which denoted a high capacity of the soil to incorporate the Am and a low reversibility of the sorption process. The influence of soil properties in {sup 241}Am interaction was studied by means of multiple linear and multivariate regressions. Although a single correlation between K{sub d} (Am) values and a soil property was not found, the main properties affecting {sup 241}Am interaction in soils were soil pH, carbonate and organic matter contents in the soil. Finally, additional batch assays at different controlled pH were done to study Am sorption as a function of the contact solution pH. A variation of the Am sorption

  9. SKIN DOSIMETRY IN CONDITIONS OF ITS CONSTANT SURFACE CONTAMINATION WITH SOLUTIONS OF PLUTONIUM-239 AND AMERICIUM-241

    Directory of Open Access Journals (Sweden)

    E. B. Ershov

    2012-01-01

    Full Text Available The article considers, on the basis of experimental data, the issue of assessing dose burdens to the skin basal layer in conditions of its permanent contamination with solutions of plutonium-239 and americium-241 and subsequent decontamination.

  10. Metabolism of americium-241 in man: an unusual case of internal contamination of a child and his father

    International Nuclear Information System (INIS)

    The metabolism of americium-241 was studied during an 8-yr period of an adult male and his son who, at the ages of 50 and 4, respectively, were accidentally and unknowingly contaminated within their home by means of inhalation. Chelation therapy with Na3(Ca-DTPA) was more effective in enhancing the removal of americium-241 from the child than from his father

  11. Influence of biofilms on migration of uranium, americium and europium in the environment; Einfluss von Biofilmen auf das Migrationsverhalten von Uran, Americium und Europium in der Umwelt

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Nils; Zirnstein, Isabel; Arnold, Thuro

    2015-07-01

    The report on the influence of biofilms on migration of uranium, americium and europium in the environment deals with the contamination problems of uranium mines such as SDAG WISMUT in Saxonia and Thuringia. In mine waters microorganisms form a complex microbiological biocoenosis in spite of low pH values and high heavy metal concentrations including high uranium concentrations. The analyses used microbiological methods like confocal laser scanning microscopy and molecular-biological techniques. The interactions of microorganism with fluorescent radioactive heavy metal ions were performed with TRLFS (time resolved laser-induced fluorescence spectroscopy).

  12. Liquid-liquid extraction separation and sequential determination of plutonium and americium in environmental samples by alpha-spectrometry

    International Nuclear Information System (INIS)

    A procedure is described by which plutonium and americium can be determined in environmental samples. The sample is leached with nitric acid and hydrogen peroxide, and the two elements are co-precipitated with ferric hydroxide and calcium oxalate. The calcium oxalate is incinerated at 4500 and the ash is dissolved in nitric acid. Plutonium is extracted with tri-n-octylamine solution in xylene from 4M nitric acid and stripped with ammonium iodide/hydrochloric acid. Americium is extracted with thenoyltrifluoroacetone solution in xylene at pH 4 together with rare-earth elements and stripped with 1M nitric acid. Americium and the rare-earth elements thus separated are sorbed on Dowex 1 x 4 resin from 1M nitric acid in 93% methanol, the rare-earth elements are eluted with 0.1M hydrochloric acid/0.5M ammonium thiocyanate/80% methanol and the americium is finally eluted with 1.5M hydrochloric acid in 86% methanol. Plutonium and americium in each fraction are electro-deposited and determined by alpha-spectrometry. Overall average recoveries are 81% for plutonium and 59% for americium. (author)

  13. Electrodeposition of americium on a liquid cadmium cathode from a molten salt bath

    International Nuclear Information System (INIS)

    A high-activity experiment involving the electrode position of americium on a liquid cadmium cathode from a LiCl-KCl eutectic with about 3 g of AmO2 was conducted in a shielded cell in the ATALANTE complex. After describing the electrolyzer and the experimental conditions, the authors discuss the preparation of the LiCl-KCl-AmCl3 solution and briefly review its electrochemical properties. It was clearly confirmed that Am(III) reduction on an inert solid cathode occurs in two steps forming Am(II) before Am(0), whereas only one reduction step was observed on liquid cadmium. The main results of this study concern americium electrode position on the liquid cadmium cathode (recovery yields, current densities, problems encountered). The solvent properties of cadmium for actinide/lanthanide separation are discussed. (authors)

  14. Experimental Insight into the Radiation Resistance of Zirconia-Based Americium Ceramics

    International Nuclear Information System (INIS)

    Our works shows that the americium pyrochlore 241Am2Zr2O7 undergoes a phase transition to a defect-fluorite structure along with an unusual volume contraction when subjected to internal radiation from α-emitting actinides. Disorder relaxation proceeds through the simultaneous formation of cation anti sites and oxygen Frenkel pairs. X-ray absorption spectroscopy at the Am-LII and the Zr-K edges reveals that Am-O polyhedra show an increasing disorder with increasing exposure. In contrast, the Zr-O polyhedral units remain highly ordered, while rotating along edges and corners, thereby reducing the structural strain imposed by the growing disorder around americium. We believe it is this particular property of the compound that provides the remarkable resistance to radiation (≥9.4 * 1018) α-decay events g-1 or 0.80 dpa). (authors)

  15. Influence of some organic additives on the extractive separation of americium(III) by sulfoxides

    International Nuclear Information System (INIS)

    The solvent extraction behavior of americium(III) from aqueous nitrate media by two long-chain aliphatic sulfoxides has been examined systematically in the presence of several water-miscible organic solvents to study their possible synergistic effect on metal ion extraction. Methanol, ethanol, n- and isopropanol, n-butanol, dioxane, acetone, as well as acetonitrile, were employed as the organic component of the mixed (polar) phase. These additives affected the extraction to varying degrees. Extractability of Am increased 5 to 10-fold with increasing concentration of some of these additives, with the maximum enhancement being observed in the presence of acetone or acetonitrile. However, alcohols are generally very poor in this respect. Possible reasons for such behavior are briefly discussed. The distribution of several common contaminants was also investigated at the optimum condition for americium extraction

  16. Transmutation of americium and curium incorporated in zirconia-based host materials

    International Nuclear Information System (INIS)

    Presented are studies involving the incorporation of americium and curium in zirconia-based materials. First explored was the pseudo ternary system AmO2-ZrO2-Y2O3. It was determined that selected Y-CSZ materials can incorporate significant quantities of americium oxide and remain cubic single-phase. The cell parameters of these fluorite-type products were established to be linear with the AmO2 content. The Cm2O3-ZrO2 system was also investigated. It was found that at 25 mol% of CmO1.5, the Cm(III) stabilized zirconia in its cubic form (a = 5.21 ±0.01 Angstrom). At higher and lower concentrations, diphasic materials were encountered. At 50 mol% of CmO1.5, a pyrochlore oxide - Cm2Zr2O7 - is formed (a = 10.63 ±0.02 Angstrom). (author)

  17. Americium and samarium determination in aqueous solutions after separation by cation-exchange

    International Nuclear Information System (INIS)

    The concentration of trivalent americium and samarium in aqueous samples has been determined by means of alpha-radiometry and UV-Vis photometry, respectively, after chemical separation and pre-concentration of the elements by cation-exchange using Chelex-100 resin. Method calibration was performed using americium (241Am) and samarium standard solutions and resulted in a high chemical recovery for cation-exchange. Regarding, the effect of physicochemical parameters (e.g. pH, salinity, competitive cations and colloidal species) on the separation recovery of the trivalent elements from aqueous solutions by cation-exchange has also been investigated. The investigation was performed to evaluate the applicability of cation-exchange as separation and pre-concentration method prior to the quantitative analysis of trivalent f-elements in water samples, and has shown that the method could be successfully applied to waters with relatively low dissolved solid content. (author)

  18. Analysis of americium-beryllium neutron source composition using the FRAM code

    Energy Technology Data Exchange (ETDEWEB)

    Hypes, P. A. (Philip A.); Bracken, D. S. (David S.); Sampson, Thomas E.; Taylor, W. A. (Wayne A.)

    2002-01-01

    The FRAM code was originally developed to analyze high-resolution gamma spectra from plutonium items. Its capabilities have since been expanded to include analysis of uranium spectra. The flexibility of the software also enables a capable spectroscopist to use FRAM to analyze spectra in which neither plutonium nor uranium is present in significant amounts. This paper documents the use of FRAM to determine the {sup 239}Pu/{sup 241}Am, {sup 243}Am/{sup 241}Am, {sup 237}Np/{sup 241}Am, and {sup 239}Np/{sup 241}Am ratios in americium-beryllium neutron sources. The effective specific power of each neutron source was calculated from the ratios determined by FRAM in order to determine the americium mass of each of these neutron sources using calorimetric assay. We will also discuss the use of FRAM for the general case of isotopic analysis of nonplutonium, nonuranium items.

  19. Influence of environmental factors on the gastrointestinal absorption of plutonium and americium

    International Nuclear Information System (INIS)

    The absorption of plutonium and americium from the gastrointestinal tract was studied, using adult hamsters and rabbits. Both actinides were administered as inorganic compounds, as organic complexes with naturally occurring chelating agents, and in a biologically incorporated form in liver tissues. The absorption of the tetravalent and hexavalent forms of plutonium were compared and the effect of protracted administration at very low concentrations was investigated. In addition, plutonium uptake from contaminated sediments and grass, collected near a nuclear-fuel reprocessing plant, was measured. The results of these studies suggest that chronic exposure of man to plutonium and americium in food and water will not lead to any substantial increase in their gastrointestinal absorption above the values currently recommended by the International Commission on Radiological Protection to define the occupational exposure of workers

  20. Contemporary state of plutonium and americium in the soils of Palesse state radiation-ecological reserve

    International Nuclear Information System (INIS)

    Full text: At present, the most important alpha-emitting radionuclides of Chernobyl origin are Pu 238, Pu 239, Pu 240 and Am 241. They are classified as the most dangerous group of radionuclides in view of the long half-lives and high radiotoxicity. The main part of alpha-emitted radionuclides is located within the Palesse State Radiation-Ecological Reserve. One of the most important factors determining the radioecological situation in the contaminated ecosystems is the physicochemical forms of radionuclides in a soil medium. Radionuclide species determine the radionuclide entrance into the soil solutions, their redistribution in soil profiles and the 'soil - plant' and the 'soil - surface, ground or underground water' systems as well as spreading beyond the contaminated area. The present work is devoted to investigation of state and migration ability of plutonium and americium in soils of the Palesse state radiation-ecological reserve after more than 20 years from the Chernobyl accident. The objects of investigation were mineral and organic soils sampled in 2008 with the step of 5 cm to the depth of 25-30 cm. The forms of plutonium and americium distinguishing by association with the different components of soil and by potential for migration in the soil medium were studied using the method of sequential selective extraction according to the modified Tessier scheme. Activities of Pu 238, Pu 239, Pu 240 and Am 241 in the samples were determined by the method of radiochemical analysis with alpha-spectrometer radionuclide identification. The dominant part of plutonium and americium in the soils is in immobile forms. Nowadays, radionuclide portions in water soluble and reversibly bound forms do not exceed 9.4 % of radionuclide content in the soil. In mineral soil samples, the radionuclide portions in these fractions exceed the corresponding portions in organic ones. In both mineral and organic soils, the portions of mobile americium are higher than plutonium. The

  1. Standard test method for quantitative determination of americium 241 in plutonium by Gamma-Ray spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1994-01-01

    1.1 This test method covers the quantitative determination of americium 241 by gamma-ray spectrometry in plutonium nitrate solution samples that do not contain significant amounts of radioactive fission products or other high specific activity gamma-ray emitters. 1.2 This test method can be used to determine the americium 241 in samples of plutonium metal, oxide and other solid forms, when the solid is appropriately sampled and dissolved. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  2. Fabrication of neptunium, plutonium, americium and curium metals for fuel research

    International Nuclear Information System (INIS)

    The techniques for the fabrication of actinide metals; neptunium, americium and curium called as minor actinides, and plutonium, are surveied in a viewpoint of the preparation of starting materials for fuel property measurements. In this report, the processes of the conversion to metals, purification et al. are reviewed. The concept related to the apparatus design is also proposed and the considerable subjects are discussed. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Adam C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Belooussova, Olga N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hetrick, Lucas Duane [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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.

  4. Fabrication of uranium–americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    International Nuclear Information System (INIS)

    Highlights: • Dust free process for (U,Am)O2 transmutation target fabrication. • Synthesis of U0.9Am0.1O2 mixed oxide microspheres from ion exchange resin. • Fabrication of dense U0.9Am0.1O2 pellet with 95% TD from mixed oxide microspheres. - Abstract: 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

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

    International Nuclear Information System (INIS)

    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 220C, 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 900C 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 220C 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

  6. Bidentate organophosphorus extraction of americium and plutonium from Hanford Plutonium Reclamation Facility waste

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, W.W.

    1974-09-01

    Applicability of bidentate organiphosphorus reagents to recovery of americium and plutonium from Hanford's Plutonium Reclamation Facility acid (approx. 2M HNO/sub 3/) waste stream (CAW solution) was studied. A solvent extraction process which employs a 30% DHDECMP (dihexyl-N, N-diethylcarbamylmethylene phosphonate)-CCl/sub 4/ extractant was devised and successfully tested in mixer-settler runs with actual CAW solution. Substitution of DHDECMP for DBBP eliminates the need to perform careful neutralization of unbuffered CAW soluton and increases overall americium recovery from the present 60 to 80% level to greater than or equal to 90%. Disadvantages to such substitution include the high cost (approx. $50/liter) of DHDECMP and the need to purify it (by acid (6M HCl) hydrolysis and alkaline washing) from small amounts of an unidentified impurity which prevents stripping of americium with dilute HNO/sub 3/. Distribution data obtained in this study confirm Siddall's earlier contention that bidentate organophosphorus regents can be used to remove actinides from concentrated high-level Purex process acid waste; a conceptual flowsheet for such an extraction process is given.

  7. Selective recovery of americium alone from PUREX or COEXTM raffinate by the EXAm process

    International Nuclear Information System (INIS)

    Americium is the main contributor to the long-term radiotoxicity and to the heat generation of glasses used for the HLW conditioning. To decrease both impact on the ultimate waste and to avoid the difficult recycling of curium, the CEA has developed the EXAm process for the the separation and the recovery of the sole americium directly from PUREX or COEXTM raffinates. The principle of the EXAm process is to extract americium and light lanthanides from high nitric acid media, leaving curium and heavy lanthanides in the raffinate. A water-soluble amide molecule, TEDGA, is added in aqueous phase to increase Am/Cm and Am/heavy lanthanides selectivity, because of the preferential complexation of curium and heavy lanthanides by this diglycolamide. Many experimental data have been acquired mainly at the extraction-scrubbing step (Am/Cm separation) and were used for the development of a phenomenological model implemented in the PAREX process simulation code. The scientific feasibility demonstration of the EXAm process was then performed on a genuine PUREX raffinate in Atalante CBP hot cell in 2010. (author)

  8. Uptake and effects of americium-241 on a brackish-water amphipod

    International Nuclear Information System (INIS)

    The present paper reports the results of experimental work undertaken using the brackish-water amphipod Gammarus duebeni duebeni and the transuranium nuclide americium-241. Data on the accumulation of this actinide showed that the larger fraction of the total body burden is associated with the exoskeleton. It was found that the body burden remained constant in the range pH 8.0-6.5 even though the water concentration changed markedly. It would thus appear that the concept of a concentration factor should be re-examined and it is proposed that a factor should be defined in terms of environmental and chemical parameters which represent the bioavailable fraction of the actinide. The effect of americium on survival and moulting was studied at two activity concentrations; the dose rates and absorbed doses under the experimental conditions employed have been estimated. The differences in survival rates between the control and irradiated groups were statistically analyzed and the significant difference at the higher concentration is believed to be due to a synergism between physiological stress and radiotoxicity of americium rather than the chemical toxicity of the element. (orig.)

  9. Selenide and telluride glasses for mid-infrared bio-sensing

    Science.gov (United States)

    Cui, Shuo; Chahal, Radwan; Shpotyuk, Yaroslav; Boussard, Catherine; Lucas, Jacques; Charpentier, Frederic; Tariel, Hugues; Loréal, Olivier; Nazabal, Virginie; Sire, Olivier; Monbet, Valérie; Yang, Zhiyong; Lucas, Pierre; Bureau, Bruno

    2014-02-01

    Fiber Evanescent Wave Spectroscopy (FEWS) is an efficient way to collect optical spectra in situ, in real time and even, hopefully, in vivo. Thanks to selenide glass fibers, it is possible to get such spectra over the whole mid-infrared range from 2 to 12 μm. This working window gives access to the fundamental vibration band of most of biological molecules. Moreover selenide glasses are stable and easy to handle, and it is possible to shape the fiber and create a tapered sensing head to drastically increase the sensitivity. Within the past decades, numerous multi-disciplinary studies have been conducted in collaboration with the City Hospital of Rennes. Clinical trials have provided very promising results in biology and medicine which have led to the creation in 2011 of the DIAFIR Company dedicated to the commercialization of fiber-based infrared biosensors. In addition, new glasses based on tellurium only have been recently developed, initially in the framework of the Darwin mission led by the European Space Agency (ESA). These glasses transmit light further into the far-infrared and could also be very useful for medical applications in the near future. Indeed, they permit to reach the vibrational bands of biomolecules laying from 12 to 16 μm where selenide glasses do not transmit light anymore. However, while Se is a very good glass former, telluride glasses tend to crystallize easily due to the metallic nature of Te bonds. Hence, further work is under way to stabilize the glass composition for fibers drawing and to lower the optical losses for improving their sensitivity as bio-sensors.

  10. Effect of He{sup +} irradiation on the optical properties of vacuum evaporated silver indium selenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh Kumar, M.C., E-mail: santhoshmc@yahoo.co [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620 015 (India); Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682 022 (India)

    2010-04-09

    We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The samples were subjected to the irradiation of 1.26 M eV He{sup +} ion. The effect of irradiation on the optical properties has been investigated for different fluencies of He{sup +}. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. It is observed that the band gap of silver indium selenide thin films decreases gradually from 1.17 to 0.82 eV with ion fluency.

  11. TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

    International Nuclear Information System (INIS)

    Highlights: • Ag2Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag2Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag2Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphine (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag2Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag2Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the structure of the PVP/Ag2Se

  12. TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

    Energy Technology Data Exchange (ETDEWEB)

    More, D.S. [Department of Chemistry, Faculty of Applied and Computer Sciences, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Moloto, M.J., E-mail: makwenam@vut.ac.za [Department of Chemistry, Faculty of Applied and Computer Sciences, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Moloto, N. [School of Chemistry, Faculty of Science, University of the Witwatersrand, Private Bag 3, Johannesburg 2050 (South Africa); Matabola, K.P. [Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg 2125 South Africa (South Africa)

    2015-05-15

    Highlights: • Ag{sub 2}Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag{sub 2}Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag{sub 2}Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphine (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag{sub 2}Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag{sub 2}Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the

  13. Analysis on the Performance of Copper Indium Gallium Selenide (CIGS) Based Photovoltaic Thermal

    OpenAIRE

    Zulkepli Afzam; Yong Lim Wei; Taib Mohd Yusof; Azran Zafri; Basrawi Firdaus

    2016-01-01

    This paper deals with the efficiency improvement of Copper Indium Gallium Selenide (CIGS) Photovoltaic (PV) and also solar thermal collector. Photovoltaic thermal (PV/T) can improve overall efficiency for PV and also solve the problem of limited roof space at urban area. Objective of this study is to clarify the effect of mass flow rate on the efficiency of the PV/T system. A CIGS solar cell is used with rated output power 65 W and 1.18 m2 of area. 4 set of experiments were carried out, which...

  14. Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

    KAUST Repository

    Lee, Kyu-Sung

    2011-12-01

    We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

  15. Polarity and structure peculiarities of trialkylphosphine oxides, sulfides, selenides and tellurides

    International Nuclear Information System (INIS)

    Using the quantum-chemical calculations structural characteristics of trialkylphosphine oxides, sulfates, selenides and tellurides (Alk3P=X; X O, S, Se, Te) are obtained, which are in good agreement with literature X-ray structural analysis and gas-phase electron diffraction data. The P=X bonds polarity is determined in the framework of vector-additive scheme on the base of experimental data on components dipole moments and using different base series of molecules geometry parameters. It is shown that increasing of bond moment P=X in the X = O, S, Se, Te series takes place through dipole length increasing

  16. Structural, optical and electrical properties of chemically deposited copper selenide films

    Indian Academy of Sciences (India)

    R H Bari; V Ganesan; S Potadar; L A Patil

    2009-02-01

    Stoichiometric and nonstoichiometric thin films of copper selenide have been prepared by chemical bath deposition technique at temperature below 60°C on glass substrate. The effect of nonstoichiometry on the optical, electrical and structural properties of the film was studied. The bandgap energy was observed to increase with the increase in at % of copper in composition. The grain size was also observed to increase with the decrease of at % of copper in composition. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), absorption spectroscopy, and AFM. The results are discussed and interpreted.

  17. Solution-Liquid-Solid Synthesis of Hexagonal Nickel Selenide Nanowire Arrays with a Nonmetal Catalyst.

    Science.gov (United States)

    Xu, Kun; Ding, Hui; Jia, Kaicheng; Lu, Xiuli; Chen, Pengzuo; Zhou, Tianpei; Cheng, Han; Liu, Si; Wu, Changzheng; Xie, Yi

    2016-01-26

    Inorganic nanowire arrays hold great promise for next-generation energy storage and conversion devices. Understanding the growth mechanism of nanowire arrays is of considerable interest for expanding the range of applications. Herein, we report the solution-liquid-solid (SLS) synthesis of hexagonal nickel selenide nanowires by using a nonmetal molecular crystal (selenium) as catalyst, which successfully brings SLS into the realm of conventional low-temperature solution synthesis. As a proof-of-concept application, the NiSe nanowire array was used as a catalyst for electrochemical water oxidation. This approach offers a new possibility to design arrays of inorganic nanowires. PMID:26695560

  18. Electrical properties of silver selenide thin films prepared by reactive evaporation

    Indian Academy of Sciences (India)

    M C Santhosh Kumar; B Pradeep

    2002-10-01

    The electrical properties of silver selenide thin films prepared by reactive evaporation have been studied. Samples show a polymorphic phase transition at a temperature of 403 ± 2 K. Hall effect study shows that it has a mobility of 2000 cm2V–1s–1 and carrier concentration of 1018 cm–3 at room temperature. The carriers are of -type. X-ray diffraction study indicates that the as-prepared films are polycrystalline in nature. The lattice parameters were found to be = 4.353 Å, = 6.929 Å and = 7.805 Å.

  19. About the reaction between uranium-americium mixed oxides and sodium

    International Nuclear Information System (INIS)

    The recycling and fission of the highly toxic minor actinides neptunium and americium is only possible in a liquid metal cooled fast breeder reactor, for nuclear physical reasons. The present work is part of a research program dealing with the fuel-coolant interaction. Fuel pellets with equal parts of americium and uranium and varying oxygen-metal ratio were investigated. A behaviour comparable to that of uranium-plutonium mixed oxides was suggested as a first approach. The reaction of sodium with (U0.5Am0.5)O2-x results in a complete desintegration of the sintered pellet whereas (U, Pu)O2-x pellets show a small increase in volume. A first explanation of the strong reaction of uranium-americium mixed oxides compared to (U, Pu)O2-x or (U, Np)O2-x could be provided by the less negative oxygen potential of the former. Ternary and polynary oxides which are possible products of the fuel-coolant reaction were prepared and characterised by X-ray diffraction. Their oxygen potentials were measured using a solid state e.m.f. cell. Neither Na2AmO3 nor Na3AmO4 can coexist with sodium metal. The measured ΔGO2 values of the Am(IV) and Am (V)-compounds are much higher than those of the sodium uranates(VI) or sodium neptunates(VI). Only Na2O seems to be likely as product of the fuel-coolant interactions. It could be determined in reacted samples by X-ray diffraction. The relatively high oxygen potentials of (U0.5Am0.5)O2-x that are responsible for the reaction could be explained by a binding model which is based on an americium valency state of + 3 and U5+. The existence of both valency states could be proved by XPS measurements. Due to the similar behaviour of neptunium and uranium the problems that are expected for the recycling of Np are much smaller than for americium

  20. Compatibility of Pt-3008 with selected components of the selenide isotope generator system

    International Nuclear Information System (INIS)

    The first in a new generation of radioisotopic thermoelectric generators being built by Teledyne Energy Systems and designated the Selenide Isotope Generator has thermoelectric materials that can be degraded by reaction with O2, H2O, CO, and other gases. Consequently, for at least the first ground demonstration system a protective xenon atmosphere will be maintained over the thermoelectrics. The high-temperature portion of the atmosphere-retaining structure will be fabricated from the alloy Pt-3008 (Pt--30 wt % Rh--8 wt % W), which was developed at Oak Ridge National Laboratory. For this application Pt-3008 must be compatible with the various insulations and thermoelectric materials. A study of the compatibility of Pt-3008 with these materials and showed that Pt-3008 was embrittled after exposure to some of the insulations that were not adequately outgassed and by one of the thermoelectric materials (Cu2Se) in some of the isothermal tests. It is believed that Pt-3008 will be compatible with the Selenide Isotope Generator materials when they are well outgassed and under the temperature gradient conditions of the operating system

  1. Asymmetric supercapacitors with metal-like ternary selenides and porous graphene electrodes

    KAUST Repository

    Xia, Chuan

    2016-04-14

    Asymmetric supercapacitors provide a promising approach to fabricate capacitive energy storage devices with high energy and power densities. In this work, asymmetric supercapacitors with excellent performance have been fabricated using ternary (Ni, Co)0.85Se on carbon fabric as bind-free positive electrode and porous free-standing graphene films as negative electrode. Owing to their metal-like conductivity (~1.67×106 S m−1), significant electrochemical activity, and superhydrophilic nature, our nanostructured ternary nickel cobalt selenides result in a much higher areal capacitance (2.33 F cm−2 at 4 mA cm−2), better rate performance and cycling stability than their binary selenide equivalents, and other ternary oxides and chalcogenides. Those hybrid supercapacitors can afford impressive areal capacitance and stack capacitance of 529.3 mF cm−2 and 6330 mF cm−3 at 1 mA cm−2, respectively. More impressively, our optimized asymmetric device operating at 1.8 V delivers a very high stack energy density of 2.85 mWh cm−3 at a stack power density of 10.76 mW cm−3, as well as 85% capacitance retention after 10,000 continuous charge-discharge cycles. Even at a high stack power density of 1173 mW cm−3, this device still deliveries a stack energy density of 1.19 mWh cm−3, superior to most of the reported supercapacitors.

  2. Photoluminescence of Nitrogen-Doped Zinc Selenide by Photo-Assisted Mocvd.

    Science.gov (United States)

    Gillespie, Paul Matthew

    Zinc selenide is a wide band-gap (2.67 eV) II -VI compound semiconductor with potential use as a blue electro-optic device material. Problems with obtaining suitable p-type conductivity have limited device development. Zinc selenide epitaxial films, doped with nitrogen from NH _3, have been grown on gallium arsenide substrates by laser-assisted metal organic chemical vapor deposition (MOCVD). The effect of nitrogen doping was investigated with and without direct surface irradiation incident on the surface from a broad-band light source. Low temperature (8 K) photoluminescence spectroscopy has confirmed the incorporation of nitrogen as a shallow acceptor by the presence of acceptor-bound-excitons and associated donor -acceptor-pair recombination emissions. The MOCVD growth parameters have been optimized based on the presence of characteristic features in the photoluminescence spectra. Growth rate mechanisms have been proposed for both laser-assisted MOCVD and direct-irradiation MOCVD. Simultaneous interaction of the two photo-assisted techniques show that direct irradiation of the surface does not enhance the growth rate under the laser-assisted condition. This confirms that direct surface irradiation growth mechanisms involve the interaction of photo-generated carriers with alkyl groups from the precursors.

  3. Transparent metal selenide alloy counter electrodes for high-efficiency bifacial dye-sensitized solar cells.

    Science.gov (United States)

    Duan, Yanyan; Tang, Qunwei; Liu, Juan; He, Benlin; Yu, Liangmin

    2014-12-22

    The exploration of cost-effective and transparent counter electrodes (CEs) is a persistent objective in the development of bifacial dye-sensitized solar cells (DSSCs). Transparent counter electrodes based on binary-alloy metal selenides (M-Se; M=Co, Ni, Cu, Fe, Ru) are now obtained by a mild, solution-based method and employed in efficient bifacial DSSCs. Owing to superior charge-transfer ability for the I(-) /I3 (-) redox couple, electrocatalytic activity toward I3 (-) reduction, and optical transparency, the bifacial DSSCs with CEs consisting of a metal selenide alloy yield front and rear efficiencies of 8.30 % and 4.63 % for Co0.85 Se, 7.85 % and 4.37 % for Ni0.85 Se, 6.43 % and 4.24 % for Cu0.50 Se, 7.64 % and 5.05 % for FeSe, and 9.22 % and 5.90 % for Ru0.33 Se in comparison with 6.18 % and 3.56 % for a cell with an electrode based on pristine platinum, respectively. Moreover, fast activity onset, high multiple start/stop capability, and relatively good stability demonstrate that these new electrodes should find applications in solar panels. PMID:25358619

  4. From zinc selenate to zinc selenide nano structures synthesized by reduction process

    International Nuclear Information System (INIS)

    One-dimensional nano structure materials are very attractive because of their electronic and optical properties depending on their size. It is well known that properties of material can be tuned by reducing size to nano scale because at the small sizes, that they behave differently with its bulk materials and the band gap will control by the size. The tunability of the band gap makes nano structured materials useful for many applications. As one of the wide band gaps semiconductor compounds, zinc selenide (ZnSe) nano structures (nanoparticles, nano wires, nano rods) have received much attention for the application in optoelectronic devices, such as blue laser diode, light emitting diodes, solar cells and IR optical windows. In this study, ZnSe nano structures have been synthesized by reduction process of zinc selenate using hydrazine hydrate (N2H4.2H2O). The reductive agent of hydrazine hydrate was added to the starting materials of zinc selenate were heat treated at 500 degree Celsius for 1 hour under argon flow to form one-dimensional nano structures. The SEM and TEM images show the formation of nano composite-like structure, which some small nano bar and nano pellets stick to the rod. The x-ray diffraction and elemental composition analysis confirm the formation of mixture zinc oxide and zinc selenide phases. (author)

  5. Methylselenol formed by spontaneous methylation of selenide is a superior selenium substrate to the thioredoxin and glutaredoxin systems.

    Directory of Open Access Journals (Sweden)

    Aristi P Fernandes

    Full Text Available Naturally occurring selenium compounds like selenite and selenodiglutathione are metabolized to selenide in plants and animals. This highly reactive form of selenium can undergo methylation and form monomethylated and multimethylated species. These redox active selenium metabolites are of particular biological and pharmacological interest since they are potent inducers of apoptosis in cancer cells. The mammalian thioredoxin and glutaredoxin systems efficiently reduce selenite and selenodiglutathione to selenide. The reactions are non-stoichiometric aerobically due to redox cycling of selenide with oxygen and thiols. Using LDI-MS, we identified that the addition of S-adenosylmethionine (SAM to the reactions formed methylselenol. This metabolite was a superior substrate to both the thioredoxin and glutaredoxin systems increasing the velocities of the nonstoichiometric redox cycles three-fold. In vitro cell experiments demonstrated that the presence of SAM increased the cytotoxicity of selenite and selenodiglutathione, which could neither be explained by altered selenium uptake nor impaired extra-cellular redox environment, previously shown to be highly important to selenite uptake and cytotoxicity. Our data suggest that selenide and SAM react spontaneously forming methylselenol, a highly nucleophilic and cytotoxic agent, with important physiological and pharmacological implications for the highly interesting anticancer effects of selenium.

  6. Formation of Cadmium Selenide Containing Layers on the Polyamide Film Surface by the Use of Potassium Selenotrithionate

    Directory of Open Access Journals (Sweden)

    Neringa PETRASAUSKIENE

    2015-05-01

    Full Text Available The layers containing cadmium selenide, CdxSe, were formed on the surface of semi hydrophilic polymer – polyamide 6 (PA for the first time by sorption-diffusion method using acidified solution of potassium selenotrithionate, K2SeS2O6, as a precursor of selenium. The concentration of sorbed selenium increases with the increase of the duration of PA treatment in K2SeS2O6 solution. The cadmium selenide containing layers form on the surface of PA after the treatment of seleniumized polymer with cadmium acetate, Cd(CH3COO2·2H2O, solution: the anions SeS2O62– containing selenium atoms of low oxidation state react with the cadmium(II ions. The conditions of a polymer initial seleniumization and of seleniumized PA treatment with cadmium acetate solution determine the concentration of cadmium and the composition of chalcogenide layer. The concentration of cadmium in the chalcogenide layer increases with the increase of initial chalcogenization duration only up to about 2 h and the temperature of selenotrithionate solution. XRD confirmed the formation of cadmium selenide containing layers on the surface of PA. The results of XPS and XRD patterns study of not earlier studied CdSe containing layers on PA showed their phase composition of two cadmium selenide phases – zinc blende (cubic CdSe, wurtzite (hexagonal CdSe, cadmium(II oxide, CdO, and cadmium(II hydroxide, Cd(OH2. Accordingly data of XRD and XPS analysis the composition of CdSe containing layers depends on the conditions of these layers formation. The data determined enable formation of the layers containing cadmium selenide on the surface of PA by the sorption-diffusion method using the solution of potassium selenotrithionate as a precursor of selenium.

  7. Americium(3) coordination chemistry: An unexplored diversity of structure and bonding

    Energy Technology Data Exchange (ETDEWEB)

    Fedosseev, A.M.; Grigoriev, M.S.; Budantseva, N.A. [A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Moscow (Russian Federation); Guillaumont, D.; Den Auwer, Ch.; Moisy, Ph. [CEA Marcoule, Nuclear Energy Division, RadioChemistry and Processes Department, 30 (France); Le Naour, C.; Simoni, E. [CNRS, University Paris-11 Orsay, IPN, 91 - Orsay (France)

    2010-06-15

    The comparison of the physicochemical behavior of the actinides with that of the lanthanides can be justified by the analogy of their electronic structure, as each of the series is made up of elements corresponding to the filling of a given (n)f atomic shell. However relatively few points of comparison are available, given the lack of available structure for trans-plutonium(III) elements and the additional difficulty of stabilizing coordination complexes of uranium(III) to plutonium(III). This contribution is a focal point of trans-plutonium(III) chemistry and, more specifically, of some americium compounds that have been recently synthesized, all related with hard acid oxygen donor ligands that may be involved in the reprocessing chain of nuclear fuel. After a brief review of the solid hydrates and aquo species for the lanthanide and actinide families, we discuss two types of ligands that have in common three carboxylic groups, namely the amino-tri-acetic acid and the citric acid anions. The additional roles of the nitrogen atom for the first one and of the hydroxy function for the second one are discussed. Accordingly, five new complexes with either americium or lanthanides elements are described: [Co(NH{sub 3}){sub 6}][M(NTA){sub 2}(H{sub 2}O)].8H{sub 2}O with M Nd, Yb and Am, and [Co(NH{sub 3}){sub 6}]{sub 2}K[M{sub 3}(Cit){sub 4}(H{sub 2}O){sub 3}].18H{sub 2}O with Nd and Am cations. In all cases the americium complexes are isostructural with their lanthanide equivalents. (authors)

  8. Americium(3) coordination chemistry: An unexplored diversity of structure and bonding

    International Nuclear Information System (INIS)

    The comparison of the physicochemical behavior of the actinides with that of the lanthanides can be justified by the analogy of their electronic structure, as each of the series is made up of elements corresponding to the filling of a given (n)f atomic shell. However relatively few points of comparison are available, given the lack of available structure for trans-plutonium(III) elements and the additional difficulty of stabilizing coordination complexes of uranium(III) to plutonium(III). This contribution is a focal point of trans-plutonium(III) chemistry and, more specifically, of some americium compounds that have been recently synthesized, all related with hard acid oxygen donor ligands that may be involved in the reprocessing chain of nuclear fuel. After a brief review of the solid hydrates and aquo species for the lanthanide and actinide families, we discuss two types of ligands that have in common three carboxylic groups, namely the amino-tri-acetic acid and the citric acid anions. The additional roles of the nitrogen atom for the first one and of the hydroxy function for the second one are discussed. Accordingly, five new complexes with either americium or lanthanides elements are described: [Co(NH3)6][M(NTA)2(H2O)].8H2O with M Nd, Yb and Am, and [Co(NH3)6]2K[M3(Cit)4(H2O)3].18H2O with Nd and Am cations. In all cases the americium complexes are isostructural with their lanthanide equivalents. (authors)

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

    Science.gov (United States)

    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

  10. Fabrication of uranium–americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    Energy Technology Data Exchange (ETDEWEB)

    Remy, E. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Picart, S., E-mail: sebastien.picart@cea.fr [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Delahaye, T. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Jobelin, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Lebreton, F.; Horlait, D. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Bisel, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Blanchart, P. [Heterogeneous Materials Research Group, Centre Européen de la Céramique, F-87068 Limoges (France); Ayral, A. [Institut Européen des Membranes, CNRS-ENSCM-UM2, CC47, University Montpellier 2, F-34095 Montpellier cedex 5 (France)

    2014-10-15

    Highlights: • Dust free process for (U,Am)O{sub 2} transmutation target fabrication. • Synthesis of U{sub 0.9}Am{sub 0.1}O{sub 2} mixed oxide microspheres from ion exchange resin. • Fabrication of dense U{sub 0.9}Am{sub 0.1}O{sub 2} pellet with 95% TD from mixed oxide microspheres. - Abstract: 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 U{sub 0.9}Am{sub 0.1}O{sub 2±δ} is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U{sub 0.9}Am{sub 0.1}O{sub 2±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.

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

    International Nuclear Information System (INIS)

    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 (III 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

  12. Recovery of Americium-241 from lightning rod by the method of chemical treatment

    International Nuclear Information System (INIS)

    About 95% of the lightning rods installed in the Peruvian territory have set in their structures, pose small amounts of radioactive sources such as Americium-241 (241Am), fewer and Radium 226 (226Ra) these are alpha emitters and have a half life of 432 years and 1600 years respectively. In this paper describes the recovery of radioactive sources of 241Am radioactive lightning rods using the conventional chemical treatment method using agents and acids to break down the slides. The 241Am recovered was as excitation source and alpha particle generator for analysing samples by X Ray Fluorescence, for fixing the stainless steel 241Am technique was used electrodeposition. (author)

  13. Report of scouting study on precipitation of strontium, plutonium, and americium from Hanford complexant concentrate waste

    International Nuclear Information System (INIS)

    A laboratory scouting test was conducted of precipitation methods for reducing the solubility of radionuclides in complexant concentrate (CC) waste solution. The results show that addition of strontium nitrate solution is effective in reducing the liquid phase activity of 90Sr (Strontium) in CC waste from tank 107-AN by 94% when the total strontium concentration is adjusted to 0.1 M. Addition of ferric nitrate solution effective in reducing the 241Am (Americium) activity in CC waste by 96% under the conditions described in the report. Ferric nitrate was also marginally effective in reducing the solubility of 239/240Pu (Plutonium) in CC waste

  14. Plutonium and americium in arctic waters, the North Sea and Scottish and Irish coastal zones

    DEFF Research Database (Denmark)

    Hallstadius, L.; Aarkrog, Asker; Dahlgaard, Henning;

    1986-01-01

    Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were...... plutonium from the latter to Spitsbergen waters. Fallout plutonium in Arctic waters has a residence time of the order of several years, while for Pu from Sellafield we estimate mean residence times of 11–15 months in Scottish waters and, tentatively, 1·5-3 y during transport from the North Channel (north...

  15. Americium and curium heterogeneous transmutation in moderated S/ A in the framework of CNE scenarios studies

    International Nuclear Information System (INIS)

    This paper presents the transmutation of Americium and Curium in a heterogeneous mode in the framework of the 1991 French Law concerning waste management. Two scenarios with moderated targets are presented: a 100% frit reactor (EFR) scenario multi-recycling Pu+Np with targets of Am+Cm placed in core and a mixed PWR (UOX fuel) and fast reactor (50% of EFR) multi-recycling Pu+Np and containing targets in core and in the blanket region. The design of the target is based on classical fast fuel S/A technology (pins, spacer wires,...) and should reach the goal of 90% fission rate. (authors)

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

    Science.gov (United States)

    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. Purification of used scintillation liquids containing the alpha emitters americium and plutonium

    International Nuclear Information System (INIS)

    In Sweden, alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. Therefore, in this work, a method for a purification of alpha active scintillation cocktails was developed. Until today (March, 2013) more than 20 L of scintillation liquids have successfully been purified from americium and plutonium. The products of the process are a solid fraction that can be sent to final storage and a practically non-radioactive liquid fraction that can be sent to municipal incineration. (author)

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

    International Nuclear Information System (INIS)

    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

  19. Plutonium and americium in arctic waters, the North Sea and Scottish and Irish coastal zones

    DEFF Research Database (Denmark)

    Hallstadius, L.; Aarkrog, Asker; Dahlgaard, Henning; Holm, E.; Boelskifte, S.; Duniec, S.; Persson, B.

    1986-01-01

    Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were...... plutonium from the latter to Spitsbergen waters. Fallout plutonium in Arctic waters has a residence time of the order of several years, while for Pu from Sellafield we estimate mean residence times of 11–15 months in Scottish waters and, tentatively, 1·5-3 y during transport from the North Channel (north of...

  20. Influence of biofilms on migration of uranium, americium and europium in the environment

    International Nuclear Information System (INIS)

    The report on the influence of biofilms on migration of uranium, americium and europium in the environment deals with the contamination problems of uranium mines such as SDAG WISMUT in Saxonia and Thuringia. In mine waters microorganisms form a complex microbiological biocoenosis in spite of low pH values and high heavy metal concentrations including high uranium concentrations. The analyses used microbiological methods like confocal laser scanning microscopy and molecular-biological techniques. The interactions of microorganism with fluorescent radioactive heavy metal ions were performed with TRLFS (time resolved laser-induced fluorescence spectroscopy).

  1. Colloidally stable selenium@copper selenide core@shell nanoparticles as selenium source for manufacturing of copper-indium-selenide solar cells.

    Science.gov (United States)

    Dong, Hailong; Quintilla, Aina; Cemernjak, Marco; Popescu, Radian; Gerthsen, Dagmar; Ahlswede, Erik; Feldmann, Claus

    2014-02-01

    Selenium nanoparticles with diameters of 100-400nm are prepared via hydrazine-driven reduction of selenious acid. The as-prepared amorphous, red selenium (a-Se) particles were neither a stable phase nor were they colloidally stable. Due to phase transition to crystalline (trigonal), grey selenium (t-Se) at or even below room temperature, the particles merged rapidly and recrystallized as micronsized crystal needles. As a consequence, such Se particles were not suited for layer deposition and as a precursor to manufacture thin-film CIS (copper indium selenide/CuInSe2) solar cells. To overcome this restriction, Se@CuSe core@shell particles are presented here. For these Se@CuSe core@shell nanoparticles, the phase transition a-Se→t-Se is shifted to temperatures higher than 100°C. Moreover, a spherical shape of the particles is retained even after phase transition. Composition and structure of the Se@CuSe core@shell nanostructure are evidenced by electron microscopy (SEM/STEM), DLS, XRD, FT-IR and line-scan EDXS. As a conceptual study, the newly formed Se@CuSe core@shell nanostructures with CuSe acting as a protecting layer to increase the phase-transition temperature and to improve the colloidal stability were used as a selenium precursor for manufacturing of thin-film CIS solar cells and already lead to conversion efficiencies up to 3%. PMID:24267336

  2. Numerical simulation for concentration profiles of americium and lanthanides in the CMPO-TBP solvent extraction system

    International Nuclear Information System (INIS)

    A numerical simulation code is developed to predict the extraction behavior of americium and lanthanides in the TRUEX (TRansUranium EXtraction)process. This code gives the concentration profiles of the components at steady state. The stage efficiency is included in this code as a parameter in order to simulate the extraction behavior of the components accurately. Concentration profiles of americium and typical lanthanides in some counter current experiments are calculated by means of the present code. The calculated concentration profiles are compared with the experimental results. The efficiency value for the mixer-settlers, which gives good agreement between the calculated and the experimental profiles, is evaluated. (author)

  3. Numerical simulation for concentration profiles of americium and lanthanides in the CMPO-TBP solvent extraction system

    International Nuclear Information System (INIS)

    A numerical simulation code for the TRUEX (TRansUranium EXtraction) process is developed to predict the extraction behavior of americium and lanthanides. This code gives the concentrations of the components at the steady state of the TRUEX process. The stage efficiency is applied to this code in order to simulate the extraction behavior of the components accurately. Concentration profiles of americium and typical lanthanides in some counter current experiments are calculated by means of the present code. The calculated profiles are compared with the experimental ones. The efficiency value for the mixer-settlers, which gives the best agreement between the two profiles, is investigated

  4. Study of the extraction and the purification of americium and trivalent actinides contained in effluents with supported liquid membranes

    International Nuclear Information System (INIS)

    The supported liquid membrane technique is studied and developed for americium recovery from uranium or plutonium matrices and decontamination of liquid radioactive wastes. First tests on uranium-nickel solutions with a flat membrane showed the easiness of the operation and the efficiency of the process. Acid-resistant (10 N), interchangeable elements with hollow fibers, are developed and also a computerized automatic device. The different tests on americium solutions demonstrate the feasibility and the reliability of the system. Influence of various parameters on transfer kinetics is investigated

  5. Experimental and in situ investigations on americium, curium and plutonium behaviour in marine benthic species: transfer from water or sediments

    International Nuclear Information System (INIS)

    The tranfer of transuranic elements -americium, curium and plutonium- from the sediments containing them to some marine benthic species (endofauna and epifauna) was studied with a twofold approach - laboratory and in-situ investigation. The experimental investigations, divided into three parts, made it possible to specify concentration factors (F.C.), transfer factors (F.T.) and to understand the process involved for 5 benthic species. The result were refined by an in-situ study that brought new data on the marine distribution of the transuranic elements released by the La Hague plant. Finally, the localization of americium and plutonium in the tissues and cells of these species was determined by autoradiography

  6. Reduction of Diaryldiselenides by System of Cp2TiCl2/ BuiMgBr/ THF and Its Application in Synthesis of Unsymmetrical Diaryl Selenides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Reduction of diaryldiselenides by the system of Cp2TiCl2/BuiMgBr/THF gave the nucleophilic arylselenium complex. They reacted with diaryl iodonium salts to afford unsymmetrical diaryl selenides in high yields.

  7. Kinetics of growth and crystal structure of cadmium selenide films during vacuum condensation

    International Nuclear Information System (INIS)

    The growth and crystal structure of cadmium selenide films on mica are studied by electron-microscopic and electron-diffraction methods. The film condensation was carried out in wide temperature ranges of sublayers and densities of falling molecular flows. It is found that to describe the film nucleation processes in the first approximation the atomistic Wolton-Rodin method may be applied. Calculated is a number of atoms in the critical nucleus and energy nucleation parameters: activation energies of nucleation energies of adsorption and surface diffusion. It is shown that the crystal structure of thick films may be determined by the correlation of areas occupied by each type of particles up to the coalescence moment, and by the kinetics of autoepitaxial growth (depending on the mica type)

  8. A Rapid and Cost-Effective Laser Based Synthesis of High Purity Cadmium Selenide Quantum Dots.

    Science.gov (United States)

    Gondall, M A; Qahtan, Talal F; Dastageer, M A; Yamani, Z H; Anjum, D H

    2016-01-01

    A rapid and cost effective method is developed to synthesize high purity cadmium Selenide (CdSe) quantum dots in acetone medium using second harmonic of Nd:YAG nanosecond pulsed laser of 532 nm wavelength. The thermal agglomeration due the nanosecond pulse duration of the laser was successfully eliminated by using unfocussed laser beam and thereby providing a favorable conditions for the synthesis of quantum dots having the grain size of 3 nm. The morphological and optical characterizations like XRD, HRTEM, optical absorption of the synthesized CdSe quantum dots, reveal that the material possesses the similar characteristics of the one synthesized through cumbersome wet chemical methods. Relative to the CdSe bulk material, the synthesized CdSe quantum dots showed a blue shift in the measured band gap energy from near infrared spectral region to visible region, making this material very attractive for many solar energy harvesting applications like photo-catalysis and solar cells. PMID:27398538

  9. Photo-induced cooperative covalent-bond switching in amorphous arsenic selenide

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, O [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-290031 (Ukraine); Balitska, V [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-290031 (Ukraine); Filipecki, J [Institute of Physics of Jan Dlugosz University, 13/15, Al. Armii Krajowej, Czestochowa, PL-42201 (Poland)

    2005-01-01

    A microstructural mechanism of photoinduced transformations in amorphous arsenic selenide films was studied with IR Fourier-spectroscopy technique in 300-100 cm{sup -1} region. It was shown that stage of irreversible photostructural changes was connected with cooperative process of coordination defect formation accompanied by homopolar chemical bonds switching in heteropolar ones. On the contrary, reversible photoinduced effects were caused by heteropolar chemical bonds switching in homopolar ones, as well as additional channel of bridge heteropolar bonds switching in short-layer ones. The both processes were associated with formation of anomalously coordinated defect pairs and accompanying atomic displacements at the level of medium-range ordering. The developed mathematical simulation procedure testified in a favour of defect-related origin of the reversible photo-thermallyinduced transformations, since their kinetics corresponded to known stretched-exponential dependence, tending to bimolecular behaviour rather then to single-exponential one.

  10. Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, M; Golovchak, R; Kozdras, A; Shpotyuk, O, E-mail: shpotyuk@novas.lviv.ua

    2010-11-15

    Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in As{sub x}Se{sub 100-x} (10 {<=} x {<=} 42) and As{sub x}S{sub 100-x} (30 {<=} x {<=} 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy As{sub x}S{sub 100-x} within 30 {<=} x < 40 range, while As{sub x}Se{sub 100-x} glasses from the same compositional interval do not show any measurable changes in DSC curves after {gamma}-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of {gamma}-induced excitations within sulfur-based network in comparison with selenium-based one.

  11. Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

    International Nuclear Information System (INIS)

    Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in AsxSe100-x (10 ≤ x ≤ 42) and AsxS100-x (30 ≤ x ≤ 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy AsxS100-x within 30 ≤ x xSe100-x glasses from the same compositional interval do not show any measurable changes in DSC curves after γ-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of γ-induced excitations within sulfur-based network in comparison with selenium-based one.

  12. Searching for new thermoelectric materials: some examples among oxides, sulfides and selenides

    International Nuclear Information System (INIS)

    Different families of thermoelectric materials have been investigated since the discovery of thermoelectric effects in the mid-19th century, materials mostly belonging to the family of degenerate semi-conductors. In the last 20 years, new thermoelectric materials have been investigated following different theoretical proposals, showing that nanostructuration, electronic correlations and complex crystallographic structures (low dimensional structures, large number of atoms per lattice, presence of ‘rattlers’…) could enhance the thermoelectric properties by enhancing the Seebeck coefficient and/or reducing the thermal conductivity. In this review, the different strategies used to optimize the thermoelectric properties of oxides and chalcogenides will be presented, starting with a review on thermoelectric oxides. The thermoelectric properties of sulfides and selenides will then be discussed, focusing on layered materials and low dimensional structures (TiS2 and pseudo-hollandites). Some sulfides with promising ZT values will also be presented (tetrahedrites and chalcopyrites). (topical review)

  13. Effect of cadmium selenide quantum dots on the dielectric and physical parameters of ferroelectric liquid crystal

    International Nuclear Information System (INIS)

    The effect of cadmium selenide quantum dots (CdSe QDs) on the dielectric relaxation and material constants of a ferroelectric liquid crystal (FLC) has been investigated. Along with the characteristic Goldstone mode, a new relaxation mode has been induced in the FLC material due to the presence of CdSe QDs. This new relaxation mode is strongly dependent on the concentration of CdSe QDs but is found to be independent of the external bias voltage and temperature. The material constants have also been modified remarkably due to the presence of CdSe QDs. The appearance of this new relaxation phenomenon has been attributed to the concentration dependent interaction between CdSe QDs and FLC molecules.

  14. Synthesis and characterization of lead selenide nanocrystal quantum dots and wires.

    Science.gov (United States)

    Seo, Weonsik; Yun, Ju-Hyung; Park, Yun Chang; Han, Chang-Soo; Lee, Jihye; Jeong, Sohee

    2011-05-01

    Lead chalcogenide nanocrystalline materials offer possibilities of improving the efficiency of various optoelectric/thermoelectric applications, especially in solar cells, by generating more carriers with incoming photons, or by extending the bandgap toward the infra-red region. In this work, we suggest the synthetic approach of creating extended PbSe structures which shows better performances when incorporated into an electric device. Firstly, we synthesized monodisperse cubic-structured single-crystalline lead selenide nanocrystal quantum dots using lead acetate and oleic acid in non-coordinating solvent without additional surfactants. Also, single-crystal cubic PbSe nanowires were synthesized in a mixture of surfactants such as trioctylphosphine and phenyl ether. Morphologies of wires and dots were precisely controlled via reaction temperature and the surface ligands. Phenyl ether was found to facilitate the oriented attachment. Further, current-voltage characteristics of drop-casted 2D arrays of nanocrystalline materials were examined. PMID:21780455

  15. Searching for new thermoelectric materials: some examples among oxides, sulfides and selenides

    Science.gov (United States)

    Hébert, S.; Berthebaud, D.; Daou, R.; Bréard, Y.; Pelloquin, D.; Guilmeau, E.; Gascoin, F.; Lebedev, O.; Maignan, A.

    2016-01-01

    Different families of thermoelectric materials have been investigated since the discovery of thermoelectric effects in the mid-19th century, materials mostly belonging to the family of degenerate semi-conductors. In the last 20 years, new thermoelectric materials have been investigated following different theoretical proposals, showing that nanostructuration, electronic correlations and complex crystallographic structures (low dimensional structures, large number of atoms per lattice, presence of ‘rattlers’…) could enhance the thermoelectric properties by enhancing the Seebeck coefficient and/or reducing the thermal conductivity. In this review, the different strategies used to optimize the thermoelectric properties of oxides and chalcogenides will be presented, starting with a review on thermoelectric oxides. The thermoelectric properties of sulfides and selenides will then be discussed, focusing on layered materials and low dimensional structures (TiS2 and pseudo-hollandites). Some sulfides with promising ZT values will also be presented (tetrahedrites and chalcopyrites).

  16. Structural, morphological and optical properties of nanocrystalline cadmium selenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khomane, A.S., E-mail: ashok_khomane@rediffmail.co [Department of Chemistry, Government Rajaram College, S.U. Road, Vidyanagar, Kolhapur 416004, Maharashtra (India)

    2010-09-17

    Research highlights: {yields} CdSe thin films deposited first time by using malic acid as a complexing agent. {yields} The film samples were characterized by XRD, SEM, UV-vis-NIR spectroscopy and TEP techniques. {yields} Nanocrystalline CdSe film can be synthesized at room temperature. - Abstract: Nanocrystalline cadmium selenide thin films have been deposited on non-conducting glass substrates. The film samples were characterized by XRD, SEM, UV-vis-NIR reflection/absorption spectroscopy and TEP techniques. The annealed film samples showed a crystalline nature with a cubic crystal structure. The optical analysis showed direct band to band type of transition. The band gap of film sample was found to be in the order of 1.7 eV. The electrical conductivity of the film sample was found to be in the order of 10{sup -6} ({Omega} cm){sup -1}. TEP measurements show n-type of conductivity.

  17. Surface structure and optical property of amorphous carbon nanotubes hybridized with cadmium selenide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Kim Han, E-mail: kimhan8419@gmail.com; Johan, Mohd Rafie [University of Malaya, Nanomaterials Engineering Research Group, Advanced Materials Research Laboratory, Department of Mechanical Engineering (Malaysia)

    2013-09-15

    Amorphous carbon nanotubes ({alpha}-CNTs) were synthesized by a chemical reaction between ferrocene and ammonium chloride at low temperature. The as-synthesized {alpha}-CNTs were then hybridized with cadmium selenide quantum dots (CdSe QDs) through a simple chemical process. Raman spectra reveal the amorphous nature of the {alpha}-CNTs surface. X-ray diffraction pattern confirmed the amorphous phase of carbon and the formation of CdSe QDs crystalline phase. Field emission scanning electron microscopy and transmission electron microscopy (TEM and HRTEM) indicate that the successfully formed hybridized {alpha}-CNTs-CdSe QDs possess an average outer diameter in the range of 110-130 nm. The CdSe QDs fall in the size range of 15-40 nm. UV-visible spectroscopy showed quantum confinement effect due to the attachment of CdSe QDs on the surface of {alpha}-CNTs.

  18. Bifacial quantum dot-sensitized solar cells with transparent cobalt selenide counter electrodes

    Science.gov (United States)

    Ma, Chunqing; Tang, Qunwei; Zhao, Zhiyuan; Hou, Mengjin; Chen, Yuran; He, Benlin; Yu, Liangmin

    2015-03-01

    Elevation of power conversion efficiency and reduction of electricity-generation cost have been two persistent objectives for quantum dot-sensitized solar cells (QDSSCs). Here we report a bifacial QDSSC structure having impressive power conversion efficiencies of 2.11% and 1.28% for front and rear irradiations, respectively. The device comprises a CdS-sensitized TiO2 anode, a transparent cobalt selenide (Co-Se) counter electrode (CE), and a liquid electrolyte containing S2-/Sn2- redox couples. Due to high optical transparency of the binary Co-Se alloy CE, incident light can penetrate the QDSSC from either front or rear side for electron excitation. A fast start-up and modest photocurrent stability are determined in the bifacial QDSSCs due to the high electron transfer kinetics in CdS-sensitized TiO2 photoanode and electrocatalytic kinetics in Co-Se CE.

  19. The role of isomorphous substitutions in natural selenides belonging to the pyrite group

    Energy Technology Data Exchange (ETDEWEB)

    Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it; Cipriani, Curzio [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Pratesi, Giovanni [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Trosti-Ferroni, Renza [Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy)

    2008-07-14

    The present paper reports chemical and structural data of selenide minerals belonging to the pyrite group. Eighteen samples of minerals in this group with variable chemical composition (7 samples of penroseite, NiSe{sub 2}; 10 samples of krutaite, CuSe{sub 2}; 1 sample of trogtalite, CoSe{sub 2}) were studied by means of X-ray single-crystal diffraction and electron microprobe. On the basis of information gained from the chemical characterization, we can conclude that a complete solid solution between NiSe{sub 2} and CuSe{sub 2} exists in nature with the absence of pure end-members. Although verified only for the Ni-rich members, we also infer a solid solution between NiSe{sub 2} and CoSe{sub 2}. The unit-cell parameters were modeled using a multiple regression method as a function of the Co, Ni, and Cu contents.

  20. Photo-induced cooperative covalent-bond switching in amorphous arsenic selenide

    International Nuclear Information System (INIS)

    A microstructural mechanism of photoinduced transformations in amorphous arsenic selenide films was studied with IR Fourier-spectroscopy technique in 300-100 cm-1 region. It was shown that stage of irreversible photostructural changes was connected with cooperative process of coordination defect formation accompanied by homopolar chemical bonds switching in heteropolar ones. On the contrary, reversible photoinduced effects were caused by heteropolar chemical bonds switching in homopolar ones, as well as additional channel of bridge heteropolar bonds switching in short-layer ones. The both processes were associated with formation of anomalously coordinated defect pairs and accompanying atomic displacements at the level of medium-range ordering. The developed mathematical simulation procedure testified in a favour of defect-related origin of the reversible photo-thermallyinduced transformations, since their kinetics corresponded to known stretched-exponential dependence, tending to bimolecular behaviour rather then to single-exponential one

  1. Effect of capping agents on optical and antibacterial properties of cadmium selenide quantum dots

    Indian Academy of Sciences (India)

    Deepika; Rakesh Dhar; Suman Singh; Atul Kumar

    2015-09-01

    Cadmium selenide quantum dots (CdSe QDs) were synthesized in aqueous phase by the freezing temperature injection technique using different capping agents (viz. thioglycolic acid, 1-thioglycerol, L-cysteine). Absorption spectra of CdSe QDs exhibited a blue shift as compared to its bulk counterpart, which is an indication of quantum confinement effect. The photoluminescence spectra of CdSe QDs confirmed that the particles are poly-dispersed and possess enhanced luminescent property, depending upon the chemical nature of capping agents. The QDs have been characterized by Fourier-transform infrared spectroscopy, atomic absorption spectroscopy and transmission electron microscopy. Further, antimicrobial activity of as-prepared QDs has also been investigated using the disk diffusion method.

  2. Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts.

    Science.gov (United States)

    Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

    2013-10-21

    Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields. PMID:24056899

  3. Transparent nickel selenide alloy counter electrodes for bifacial dye-sensitized solar cells exceeding 10% efficiency

    Science.gov (United States)

    Duan, Yanyan; Tang, Qunwei; He, Benlin; Li, Ru; Yu, Liangmin

    2014-10-01

    In the current work, we report a series of bifacial dye-sensitized solar cells (DSSCs) that provide power conversion efficiencies of more than 10% from bifacial irradiation. The device comprises an N719-sensitized TiO2 anode, a transparent nickel selenide (Ni-Se) alloy counter electrode (CE), and liquid electrolyte containing I-/I3- redox couples. Because of the high optical transparency, electron conduction ability, electrocatalytic activity of Ni-Se CEs, as well as dye illumination, electron excitation and power conversion efficiency have been remarkably enhanced. Results indicate that incident light from a transparent CE has a compensation effect to the light from the anode. The impressive efficiency along with simple preparation of the cost-effective Ni-Se alloy CEs highlights the potential application of bifacial illumination technique in robust DSSCs.In the current work, we report a series of bifacial dye-sensitized solar cells (DSSCs) that provide power conversion efficiencies of more than 10% from bifacial irradiation. The device comprises an N719-sensitized TiO2 anode, a transparent nickel selenide (Ni-Se) alloy counter electrode (CE), and liquid electrolyte containing I-/I3- redox couples. Because of the high optical transparency, electron conduction ability, electrocatalytic activity of Ni-Se CEs, as well as dye illumination, electron excitation and power conversion efficiency have been remarkably enhanced. Results indicate that incident light from a transparent CE has a compensation effect to the light from the anode. The impressive efficiency along with simple preparation of the cost-effective Ni-Se alloy CEs highlights the potential application of bifacial illumination technique in robust DSSCs. Electronic supplementary information (ESI) available: Schematic diagram, repeated J-V curves, CV curves of Ni0.85Se electrode at various scan rates, relationship between peak current density and square root of scan rates. See DOI: 10.1039/c4nr03900a

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

    International Nuclear Information System (INIS)

    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

  5. Transfer of radiocaesium, plutonium and americium to sheep after ingestion of contaminated soil

    International Nuclear Information System (INIS)

    A dual isotope method has been used to study the transfer of 137Cs, 239/240Pu and 241Am to sheep following ingestion of contaminated soil. Two soils were used; an alluvial gley contaminated by Sellafield discharges, and an organic soil, artificially contaminated in a lysimeter. Values of the true absorption coefficient of radiocaesium of 0.19 +/- 0.03 and 0.03 +/- 0.01 respectively were obtained for these soils. This implies an availability factor for soil-associated radiocaesium of up to about 20 pc compared to radiocaesium ingested in soluble form. The absorption of plutonium and americium was not significantly different for the two soils tested. Absorption of both plutonium and americium was in the range 10-5 - 10-4, with mean values of 7 x 10-5 and 4 x 10-5 obtained respectively. These values imply availability factors of around 10 pc, compared to the value of 5 x 10-4 recommended by ICRP for plutonium ingested in a comparatively available form. These results are compared with estimates of availability made using an in-vitro approach

  6. Transfer of radiocaesium, plutonium and americium to sheep after ingestion of contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, A.I.; Weekes, T.E.C. [Newcastle upon Tyne Univ. (United Kingdom). Dept. of Biological and Nutritional Sciences; Rimmer, D.L. [Newcastle upon Tyne Univ. (United Kingdom). Dept. of Agricultural and Environmental Science; Green, N.; Wilkins, B.T. [National Radiological Protection Board, Chilton (United Kingdom)

    1997-12-31

    A dual isotope method has been used to study the transfer of {sup 137}Cs, {sup 239/240}Pu and {sup 241}Am to sheep following ingestion of contaminated soil. Two soils were used; an alluvial gley contaminated by Sellafield discharges, and an organic soil, artificially contaminated in a lysimeter. Values of the true absorption coefficient of radiocaesium of 0.19 +/- 0.03 and 0.03 +/- 0.01 respectively were obtained for these soils. This implies an availability factor for soil-associated radiocaesium of up to about 20 pc compared to radiocaesium ingested in soluble form. The absorption of plutonium and americium was not significantly different for the two soils tested. Absorption of both plutonium and americium was in the range 10{sup -5} - 10{sup -4}, with mean values of 7 x 10{sup -5} and 4 x 10{sup -5} obtained respectively. These values imply availability factors of around 10 pc, compared to the value of 5 x 10{sup -4} recommended by ICRP for plutonium ingested in a comparatively available form. These results are compared with estimates of availability made using an in-vitro approach

  7. Americium and europium extraction from carbonate solutions by 1-phenyl-3-methyl-4-benzoylpyrazolone -5

    International Nuclear Information System (INIS)

    Trivalent TPEs and REEs are extractable from carbonate solutions by 1-pheny-3-methyl-4-benzoylpyrazolone-5 (PMBP). The effect of concentration of KHCO3 and K2CO3, extractant, metal, and other factors on the extent of extraction of the elements has been clarified. The kinetics of extraction of the elements from carbonate solutions has been studied. It has been shown that in the KHCO3 concentration range 0.2-2.0 M americium and europium are extracted by PMBP solutions in different diluents with distribution coefficients lying within n x 102-n x 103. From K2CO3 solutions the elements are extracted better by PMBP solutions in methyl isobutyl ketone (MIBK). It has been shown that metal concentration in the range 1x10-5. 5x10-3 g-ion x liter-1 does not affect extraction (log E = 3). Extracts based on PMBP with a metal content higher than 5x10-3g-ion x liter-1 were obtained by absolute concentrating method and were used for the study of 13C NMR spectra. The composition of thecompounds extracted by PMBP from carbonate solutions was determined by 13C NMR spectroscopy and extraction. The conditions of europium and americium reextraction from extracts based on PMBP by complexones, their mixtures with alkalis and other substances were studied. The scopes for using the system PMBP-carbonate solutions to separate and concentrate TPEs and REEs has been examined

  8. Evaluation of americium-241 toxicity influence on the microbial growth of organic wastes

    International Nuclear Information System (INIS)

    Available in abstract form only. Full text of publication follows: Since the licenses for using radioactive sources in radioactive lightning rods were lifted by the Brazilian national nuclear authority, in 1989, the radioactive devices have been replaced by Franklin type and collected as radioactive waste. However, only 20 percent of the estimated total number of installed rods was delivered to Brazilian Nuclear Commission. This situation causes concern, due to, first, the possibility of the rods being disposed as domestic waste, and second, the americium, the most commonly employed radionuclide, is classified as a high-toxicity element. In the present study, Am-241 migration experiments were performed by a lysimeter system, in order to evaluate the risk of contamination caused by radioactive lightning rods disposed as a common solid waste. Besides the risk evaluation, it is important to know the mechanism of the Am-241 release or retention in waste as well as its influence in the waste decomposition processes. Many factors are involved, but microorganisms present in the waste play an important role in its degradation, which control the physical and chemical processes. The objective of this work was to evaluate the Am-241 influence on the microbial population by counting number of cells in lysimeters leachate. Preliminary results suggest that americium may influence significantly the bacteria growth in organic waste, evidenced by culture under aerobiosis and an-aerobiosis and the antimicrobial resistance test. (authors)

  9. Contribution to the prediction of americium, plutonium and neptunium behaviour in the geosphere: chemical data

    International Nuclear Information System (INIS)

    An exhaustive bibliographic review on hydrolysis of americium gives the stability constants, at zero ionic strength. No evidence of Am(OH)4- formation was found by solubility studies up to pH 2 (CO3)3 characterised by its X-ray diffraction pattern is studied at a high ionic strength. All the published results on Am in carbonate media are reinterpreted using these stability constants (Am-OH-CO3 complexes are not needed). No evidence of Am(CO3)45- formation was found by spectrophotometry up to 3M. Literature results are used to determine the formal redox potentials at pH = 9.4 and to calculate the formation constants, at zero ionic strength. The formation of complexes between americium and humic materials (purified fulvic and humic acids) has been studied by a spectrophotometric technique. The results are interpreted by the formation of a 1:1 complexe. Solubility of the solid PuO2(CO3) is measured in bicarbonate media at high ionic strength, to obtain the solubility product and formation constants of the PuO2(CO3)i2-2i complexes

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

    International Nuclear Information System (INIS)

    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. (authors)

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

    International Nuclear Information System (INIS)

    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)

  12. Effects of Hanford high-level waste components on sorption of cobalt, strontium, neptunium, plutonium, and americium on Hanford sediments

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, C H; Barney, G S

    1983-03-01

    To judge the feasibility of continued storage of high-level waste solutions in existing tanks, effects of chemical waste components on the sorption of hazardous radioelements were determined. Experiments identified the effects of 12 Hanford high-level waste-solution components on the sorption of cobalt, strontium, neptunium, plutonium, and americium on 3 Hanford 200 Area sediments. The degree of sorption of strontium, neptunium, plutonium, and americium on two Hanford sediments was then quantified in terms of the concentrations of the influential waste components. Preliminary information on the influence of the waste components on radioelement solubility was gathered. Of the 12 Hanford waste-solution components studied, the most influential on radioelement sorption were NaOH, NaAlO/sub 2/, HEDTA, and EDTA. The chelating complexants, HEDTA and EDTA, generally decreased sorption by complexation of the radioelement metal ions. The components NaOH and NaAlO/sub 2/ decreased neptunium and plutonium sorption and increased cobalt sorption. Americium sorption was increased by NaOH. The three Hanford sediments' radioelement sorption behaviors were similar, implying that their sorption reactions were also similar. Sorption prediction equations were generated for strontium, neptunium, plutonium, and americium sorption reactions on two Hanford sediments. The equations yielded values of the distribution coefficient, K/sub d/, as quadratic functions of waste-component concentrations and showed that postulated radioelement migration rates through Hanford sediment could change by factors of 13 to 40 by changes in Hanford waste composition.

  13. Effects of Hanford high-level waste components on sorption of cobalt, strontium, neptunium, plutonium, and americium on Hanford sediments

    International Nuclear Information System (INIS)

    To judge the feasibility of continued storage of high-level waste solutions in existing tanks, effects of chemical waste components on the sorption of hazardous radioelements were determined. Experiments identified the effects of 12 Hanford high-level waste-solution components on the sorption of cobalt, strontium, neptunium, plutonium, and americium on 3 Hanford 200 Area sediments. The degree of sorption of strontium, neptunium, plutonium, and americium on two Hanford sediments was then quantified in terms of the concentrations of the influential waste components. Preliminary information on the influence of the waste components on radioelement solubility was gathered. Of the 12 Hanford waste-solution components studied, the most influential on radioelement sorption were NaOH, NaAlO2, HEDTA, and EDTA. The chelating complexants, HEDTA and EDTA, generally decreased sorption by complexation of the radioelement metal ions. The components NaOH and NaAlO2 decreased neptunium and plutonium sorption and increased cobalt sorption. Americium sorption was increased by NaOH. The three Hanford sediments' radioelement sorption behaviors were similar, implying that their sorption reactions were also similar. Sorption prediction equations were generated for strontium, neptunium, plutonium, and americium sorption reactions on two Hanford sediments. The equations yielded values of the distribution coefficient, K/sub d/, as quadratic functions of waste-component concentrations and showed that postulated radioelement migration rates through Hanford sediment could change by factors of 13 to 40 by changes in Hanford waste composition

  14. Anomalous aryl strengthening of americium and europium complexes during extraction by alkylenediphosphine dioxides from perchloric acid media

    International Nuclear Information System (INIS)

    Extraction of americium and europium from perchlorate environments by solutions of three types of methylenediphosphine dioxides, namely (C6H5)P(O)(CH2)sub(n)(O)P(C6H5)2, (C6H5)2P(O)CH2(O)P(C8H17)2 and (C8H17)2P(O)(CH2)sub(n)(O)P(C8H17)2 has been studied (n is 1 or 2 ) The diluents used have been dichlorethane and chloroform. In perchlorate environments the distribuiton coefficients of americium and europium have proved to be by about 3 orders of magnitude higher than in nitric acid environments, i.e. in perchlorate media the complexes are far more stable. Separation coefficients of americium and REE in perchloric acid soutions are much higher than in nitrate environments. The average value of Am/Eu separation coeffecient at 1-5 M acidity was about 6 (with dichlorethane as diluent) or about 7 (with chloroform as diluent). The complexes essentially exist as trisolvated. Americium complexes display anomalous stability increase upon being diluted: by about 2 orders of magnitude with dichlorethane and by up to 3 orders of magnitude with chloroform used as diluent

  15. Investigations of neutron characteristics for salt blanket models; integral fission cross section measurements of neptunium, plutonium, americium and curium isotopes

    International Nuclear Information System (INIS)

    Neutron characteristics of salt blanket micromodels containing eutectic mixtures of sodium, zirconium, and uranium fluorides were measured on FKBN-2M, BIGR and MAKET facilities. The effective fission cross sections of neptunium, plutonium, americium, and curium isotopes were measured on the neutron spectra formed by micromodels. (author)

  16. The distribution of plutonium-239 and americium-241 in the Syrian hamster following its intravenous administration as citrate

    International Nuclear Information System (INIS)

    Actinide distribution in various tissues and the skeleton of hamsters by liquid scintillation counting or isotope dilution. For plutonium 57% of activity was concentrated in the skeleton and more than 90% in the liver and skeleton after seven days. For americium the liver retained more than 50% of total activity and 25% was excreted in urine within seven days. (U.K.)

  17. One-Step Synthesis of Colloidal Quantum Dots of Iron Selenide Exhibiting Narrow Range Fluorescence in the Green Region

    International Nuclear Information System (INIS)

    The instantaneous isolation of green fluorescent colloidal quantum dots of iron selenide capped with biocompatible oleic acid is reported in this study. These iron-containing quantum dots also serve as a safe alternative to the conventionally used metal-chalcogenide systems in which the heavy metal component is usually toxic. The isolated colored colloidal solutions exhibited intense green fluorescence on exposure to ultraviolet light, which was also confirmed by photoluminescence spectroscopy. The isolated product was subjected to dynamic light scattering and transmission electron microscopy, and the particles were found to exhibit spherical morphology with an average diameter of 6-8 nm, confirming the isolation of quantum dots. The isolated iron selenide quantum dots have promising potential towards bioimaging and sensing, due to the biocompatible coating of oleic acid and iron, which also allows possibility of further chemical derivatization.

  18. SIMS study of effect of Cr adhesion layer on the thermal stability of silver selenide thin films on Si

    International Nuclear Information System (INIS)

    Effect of heat treatment on silver selenide films grown from diffusion-reaction of Ag and Se films on Cr-buffered Si substrates was investigated up to 400 deg. C. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the films. XRD patterns of the films showed stress assisted change in preferential orientation of the films upon annealing: the films annealed at 200 deg. C exhibited a strong orientation along (2 0 0) plane, which changed to (0 1 3) after annealing at 300 and 400 deg. C. Dynamic SIMS measurements showed that Cr is confined to the interface and that there is no diffusion of Cr into silver selenide

  19. Application of ion-exchange chromatography to eliminate the curium from americium by his determination by the method of liquid scintillation spectrometry

    International Nuclear Information System (INIS)

    The aim of this work is to eliminate curium in determining of americium by the method of liquid scintillation spectrometry. The paper introduces a method that has been done to eliminate curium from americium by determining of americium with liquid scintillation spectrometry method. In the research we used ion-exchange chromatography and ion-exchange sorbents DOWEX. We also observed the effect of geometry organization of column on the separation course. Resources for alpha spectrometry were prepared by micro-precipitation with neodymium chloride. High radiochemical yields were achieved, but separation did not take place according to a pre-separation scheme. (authors)

  20. The Short Series of the Oxygen-Poor Lanthanide Oxide Selenides M10OSe14 with M = La–Nd

    Directory of Open Access Journals (Sweden)

    Frank A. Weber

    2012-08-01

    Full Text Available Single crystals and phase pure samples of oxygen-poor ternary lanthanide oxide selenides with the composition M10OSe14 (M = La–Nd; tetragonal, I41/acd; a = 1592.0–1559.8 pm, c = 2106.5–2062.9 pm could be obtained by reacting the corresponding metals, selenium and selenium dioxide as oxygen source. Their crystal structures are isotypic with Pr10OS14 and thus contain isolated [OM4]10+ tetrahedra (d(O2––M3+ = 243–248 pm embedded in a complex anionic {[M6Se14]10–} lanthanide selenide matrix (d(M3+–Se2– = 288–358 pm. All three crystallographically independent M3+ cations exhibit eight contacts to chalcogenide anions (O2– and/or Se2– resulting in the formation of bicapped trigonal prismatic coordination polyhedra. The optical band gaps of the oxide selenides M10OSe14 amount to values between 1.89 and 2.04 eV indicating wide band-gap semiconductors.

  1. Purification of scintillation cocktails containing the alpha emitters americium and plutonium

    International Nuclear Information System (INIS)

    One efficient way of measuring alpha emitters is by the usage of liquid scintillation counting (LSC). A liquid sample is placed in a vial containing a scintillation cocktail. The alpha particles excite electrons in the surrounding liquid, and when they are de-excited photons are emitted. The photons are detected and the activity can be quantified. LSC has a high efficiency for alpha radiation and is therefore a fast and easy way for measuring alpha emitting samples. One drawback is that it does not differentiate very well between alpha energies; measurements of for example curium and plutonium simultaneously are impossible and demand other techniques. Another drawback is the production of a liquid alpha active waste. In Sweden alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. If, however, the activity of the liquids could be reduced by precipitation of the actinides, it would be possible to send away the liquid samples to municipal incineration. In this work a method for a purification of alpha active scintillation cocktails was developed. The method was first tried on a lab scale, and then scaled up. Until today (March, 2013) more than 20 liters of scintillation liquids have successfully been purified from americium and plutonium at Chalmers University of Technology in Sweden. The four scintillation cocktails used were Emulsifier Safe®, Hionic-Fluor®, Ultima Gold AB® and Ultima Gold XR®. The scintillation cocktails could all be purified from americium with higher yield than 95%. The yield was kept when the liquids were mixed. Also plutonium could be precipitated with a yield over 95% in all cocktails except in Hionic-Fluor® (>55%). However, that liquid in particular could be purified (>95%) by mixing it with the three other cocktails. Up-scaling was performed to a batch size of 6-8 L of scintillation cocktail. In neither the americium nor the plutonium system, adverse effects of increasing the

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

    Science.gov (United States)

    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.

  3. Recovery of plutonium and americium from chloride salt wastes by solvent extraction

    International Nuclear Information System (INIS)

    Plutonium and americium can be recovered from aqueous waste solutions containing a mixture of HCl and chloride salt wastes by the coupling of two solvent extraction systems: tributyl phosphate (TBP) in tetrachloroethylene (TCE) and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) in TCE. In the flowsheet developed, the salt wastes are dissolved in HCl, the Pu(III) is oxidized to the IV state with NaClO2 and recovered in the TBP-TCE cycle, and the Am is then removed from the resultant raffinate by the CMPO-TCE cycle. The consequences of the feed solution composition and extraction behavior of these species on the process flowsheet design, the Pu-product purity, and the decontamination of the aqueous raffinate from transuranic elements are discussed. 16 refs., 6 figs

  4. Recovery of plutonium and americium from chloride salt wastes by solvent extraction

    International Nuclear Information System (INIS)

    Plutonium and americium can be recovered from aqueous waste solutions containing a mixture of HCl and chloride salt wastes by the coupling of two solvent extraction systems: tributyl phosphate (TBP) in tetrachloroethylene (TCE) and octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) in TCE. In the flowsheet developed, the salt wastes are dissolved in HCl, the Pu(III) is oxidized to the IV state with NaClO2 and recovered in the TBP-TCE cycle, and the Am is then removed from the resultant raffinate by the CMPO-TCE cycle. The consequences of the feed solution composition and extraction behavior of these species on the process flowsheet design, the Pu-product purity, and the decontamination of the aqueous raffinate from transuranic elements are discussed

  5. The uptake of plutonium-239, 240, americium-241, strontium-90 into plants

    International Nuclear Information System (INIS)

    This report describes the results of measurements on the uptake of plutonium, americium, strontium-90 and caesium-137 into peas, beet, oats, sweet corn, tomatoes and vegetable marrow grown in tubs containing radioactively-contaminated silts. The silts had been taken from an area of West Cumbria commonly referred to as the Ravenglass estuary. The experiments are categorised as being carried out under non-standard conditions because of the manner in which the radioactivity came to be incorporated into the growth medium. The growth medium was representative of conditions which could arise when the estuarine silt moves inland under the influence of wind and tide and mixes with the adjacent farm land. The silt had been contaminated by radioactive effluents from the nuclear fuels reprocessing plant at Sellafield and this contamination had been brought about by natural means. (Auth.)

  6. Mutual separation of americium(III) and europium(III) using glycolamic acid and thioglycolamic acid

    International Nuclear Information System (INIS)

    The extractants, bis(2-ethylhexyl)diglycolamicacid (HDEHDGA) and bis(2-ethylhexy)thiodiglycolamic acid (HDEHSDGA) were synthesized and characterized by 1H and 13C NMR, mass and IR spectroscopy. The extraction behaviour of (152+154)Eu(III) and 241Am(III) from nitric acid medium by a solution of HDEHDGA (or HDEHSDGA) in n-dodecane (n-DD) was studied for the mutual separation of actinides and lanthanides. The effect of various parameters such as the pH, concentrations of HDEHDGA, HDEHSDGA, sodium nitrate, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and diethylenetriaminepentaacetic acid (DTPA) on the separation factor (SF) of americium(III) over europium(III) and vice versa was studied, and the conditions needed for the preferential separation were optimised. The results show that HDEHDGA exhibits higher extraction for (152+154)Eu(III) and HDEHSDGA shows the superior selectivity for 241Am(III). (orig.)

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

    International Nuclear Information System (INIS)

    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 241Am. 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. 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

  8. Comparative study of plutonium and americium bioaccumulation from two marine sediments contaminated in the natural environment

    International Nuclear Information System (INIS)

    Plutonium and americium sediment-animal transfer was studied under controlled laboratory conditions by exposure of the benthic polychaete Nereis diversicolor (O. F. Mueller) to marine sediments contaminated by a nuclear bomb accident (near Thule, Greenland) and nuclear weapons testing (Enewetak Atoll). In both sediment regimes, the bioavailability of plutonium and 241Am was low, with specific activity in the tissues 241Am occurred and 241Am uptake from the Thule sediment was enhanced compared to that from lagoon sediments of Enewetak Atoll. Autoradiography studies indicated the presence of hot particles of plutonium in the sediments. The results highlight the importance of purging animals of their gut contents in order to obtain accurate estimates of transuranic transfer from ingested sediments into tissue. It is further suggested that enhanced transuranic uptake by some benthic species could arise from ingestion of highly activity particles and organic-rich detritus present in the sediments. (author)

  9. A thermodynamic study of actinide oxide targets/fuels for americium transmutation

    International Nuclear Information System (INIS)

    A thermodynamic study was performed on the systems Am-O, AmOx-MgO, AmOx-MgAl2O4, Pu-Mg-O and U-Mg-O. Both experimental work (X-ray analyses, oxygen potential measurements etc.) and calculations on the phase diagrams involved were made. The reaction between americium oxide and spinel is expected to form the compound AmAlO3. Isothermal sections have been calculated for AmOx-(MgO, Al2O3), Pu-Mg-O and U-Mg-O at 2000 K using the software package ''Thermo-Calc''. Thermodynamic equilibrium data were used to predict the behaviour of actinide oxides in a reactor. The implication of the results for the technological application is discussed, with emphasis on the effects of the high oxygen potential of AmO2 as compared to the conventional fuel, i.e. UO2. (author)

  10. EURADOS action for determination of americium in skull measures in vivo and Monte Carlo simulation

    International Nuclear Information System (INIS)

    From the Group of WG7 internal dosimetry of the EURADOS Organization (European Radiation Dosimetry group, e.V.) which It coordinates CIEMAT, international action for the vivo measurement of americium has been conducted in three mannequins type skull with detectors of Germanium by gamma spectrometry and simulation by Monte Carlo methods. Such action has been raised as two separate exercises, with the participation of institutions in Europe, America and Asia. Other actions similar precede this vivo intercomparison of measurement and modeling Monte Carlo1. The preliminary results and associated findings are presented in this work. The laboratory of the body radioactivity (CRC) of service counter of dosimetry staff internal (DPI) of the CIEMAT, it has been one of the participants in vivo measures exercise. On the other hand part, the Group of numerical dosimetry of CIEMAT is participant of the Monte Carlo2 simulation exercise. (Author)

  11. Ab initio modelling of the behaviour of helium in americium and plutonium oxides

    International Nuclear Information System (INIS)

    By means of an ab initio plane wave pseudo potential method, plutonium dioxide and americium dioxide are modelled, and the behaviour of helium in both these materials is studied. We first show that a pseudo potential approach in the Generalized Gradient Approximation (GGA) can satisfactorily describe the cohesive properties of PuO2 and AmO2. We then calculate the formation energies of point defects (vacancies and interstitials), as well as the incorporation and solution energies of helium in PuO2 and AmO2. The results are discussed according to the incorporation site of the gas atom in the lattice and to the stoichiometry of PuO2±x and AmO2±x. (authors)

  12. Removal of plutonium and americium from hydrochloric acid waste stream using extraction chromatography

    International Nuclear Information System (INIS)

    Extraction chromatography is under development as a method to lower actinide activity levels in hydrochloric acid (HCl) effluent streams. Successful application of this technique would allow recycle of the largest portion of HCl, while lowering the quantity and improving the form of solid waste generated. The extraction of plutonium and americium from HCl solutions was examined for several commercial and similar laboratory-produced resins coated with n-octyl(phenyl)-N,N-diisobutylcarbamoylmethyphosphine oxide (CMPO) and either tributyl phosphate (TBP), or diamyl amylphosphonate (DAAP). Distribution coefficients for Pu and Am were measured by contact studies in hydrochloric acid solutions over the range of 0.1 - 10.0 N HCl, whole varying REDOX conditions, actinide loading levels, and contact time intervals. Significant differences in the actinide distribution coefficients, and in the kinetics of actinide removal were observed as a function of resin formulation. The usefulness of these resins for actinide removal from HCl effluent streams is discussed

  13. Complex formation of trivalent americium with salicylic acid at very low concentrations

    International Nuclear Information System (INIS)

    For the first time, the complexation of americium(III) with salicylic acid was studied at trace metal concentrations using a 2.0 m Long Path Flow Cell for UV-vis spectroscopy. The detection limit of Am(III) in aqueous solution at pH 3.0 was found to be 5 x 10-9 M. Two Am(III)-salicylate complexes were formed at pH 5.0 in 0.1 M NaClO4, indicated by a clear red shift of the absorption maximum. The absorption spectra obtained from spectrophotometric titration were analyzed by means of factor analysis and complex stabilities were calculated to be log β110 = 2.56 ± 0.08 and log β120 = 3.93 ± 0.19. (author)

  14. Standard practice for The separation of americium from plutonium by ion exchange

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This practice describes the use of an ion exchange technique to separate plutonium from solutions containing low concentrations of americium prior to measurement of the 241Am by gamma counting. 1.2 This practice covers the removal of plutonium, but not all the other radioactive isotopes that may interfere in the determination of 241Am. 1.3 This practice can be used when 241Am is to be determined in samples in which the plutonium is in the form of metal, oxide, or other solid provided that the solid is appropriately sampled and dissolved (See Test Methods C758, C759, and C1168). 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  16. Plutonium and americium concentrations and vertical profiles in some Italian mosses used as bioindicators

    International Nuclear Information System (INIS)

    We have examined the uptake of actinide elements Am and Pu by different species of lichen and moss collected in two locations (Urbino, Central Italy; Alps region, North-east Italy). Plutonium and americium were separated and determined by extraction chromatography, electrodeposition and alpha-spectrometry. This paper summarizes our results with a special emphasis on the vertical profiles of these actinides in two different species of mosses. Several 1-2 cm depth sections were obtained and dated by 210Pb method. A typical peak for 239,240Pu and 241Am was found in the very old moss species ('Sphagnum Compactum') at a depth corresponding to the period 1960-1970 which was the period characterized by the maximum nuclear weapon tests. In a younger moss species ('Neckeria Crispa') no peak was observed and the regression curves showed that Am is more mobile than 239,240Pu and 238Pu. (author)

  17. Development of the data base for a degradation model of a selenide RTG

    International Nuclear Information System (INIS)

    A new class of high temperature thermoelectric materials composed of copper, silver and selenium for the p-type and gadolinium-selenium for the n-type has been developed by the 3M Company, who also assembles the thermopile. The use of these materials for space applications (commonly referred to as the selenides) is being actively pursued by the Teledyne Corporation, under the sponsorship of ERDA. Application of this new generation of thermoelectric generators as the primary power source for unmanned spaceflight missions is under consideration by JPL. The viability of a radioisotope thermoelectric generator (RTG) strongly depends upon the long-term electrical, thermal and dimensional stability of this newly developed TPM-217 thermoelectric material. To determine independently this material's time and temperature dependent stability parameters is the goal of an extensive experimental and analytical project conducted at JPL. To realize this goal, a threefold approach is being used: (1) to determine if, and at what rate, the thermal conductance of the TPM material changes, (2) to investigate the long-term stability of the material's Seebeck voltage and electrical resistivity under current and temperature gradient conditions, and (3) to ascertain the physical behavior and compatibility of the material with surrounding insulation at elevated temperatures

  18. Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

    Science.gov (United States)

    Bercegol, Adrien; Chacko, Binoy; Klenk, Reiner; Lauermann, Iver; Lux-Steiner, Martha Ch.; Liero, Matthias

    2016-04-01

    For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoretical outlook is made using three-dimensional simulations to investigate the effect of point-contact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality, and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95%, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

  19. Highly efficient copper-zinc-tin-selenide (CZTSe) solar cells by electrodeposition.

    Science.gov (United States)

    Jeon, Jong-Ok; Lee, Kee Doo; Seul Oh, Lee; Seo, Se-Won; Lee, Doh-Kwon; Kim, Honggon; Jeong, Jeung-hyun; Ko, Min Jae; Kim, BongSoo; Son, Hae Jung; Kim, Jin Young

    2014-04-01

    Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties. PMID:24692285

  20. Multifunctional Bismuth Selenide Nanocomposites for Antitumor Thermo-Chemotherapy and Imaging.

    Science.gov (United States)

    Li, Zhenglin; Hu, Ying; Howard, Kenneth A; Jiang, Tingting; Fan, Xuelei; Miao, Zhaohua; Sun, Ye; Besenbacher, Flemming; Yu, Miao

    2016-01-26

    To integrate real-time monitoring and therapeutic functions into a single nanoagent, we have designed and synthesized a drug-delivery platform based on a polydopamine(PDA)/human serum albumin (HSA)/doxorubicin (DOX) coated bismuth selenide (Bi2Se3) nanoparticle (NP). The resultant product exhibits high stability and biocompatibility both in vitro and in vivo. In addition to the excellent capability for both X-ray computed tomography (CT) and infrared thermal imaging, the NPs possess strong near-infrared (NIR) absorbance, and high capability and stability of photothermal conversion for efficient photothermal therapy (PTT) applications. Furthermore, a bimodal on-demand pH/photothermal-sensitive drug release has been achieved, resulting in a significant chemotherapeutic effect. Most importantly, the tumor-growth inhibition ratio achieved from thermo-chemotherapy of the Bi2Se3@PDA/DOX/HSA NPs was 92.6%, in comparison to the chemotherapy (27.8%) or PTT (73.6%) alone, showing a superior synergistic therapeutic effect. In addition, there is no noticeable toxicity induced by the NPs in vivo. This multifunctional platform is, therefore, promising for effective, safe and precise antitumor treatment and may stimulate interest in further exploration of drug loading on Bi2Se3 and other competent PTT agents combined with in situ imaging for biomedical applications. PMID:26655250

  1. Light-emitting diodes made from cadmium selenide nanocrystals and a semiconducting polymer

    Science.gov (United States)

    Colvin, V. L.; Schlamp, M. C.; Alivisatos, A. P.

    1994-08-01

    ELECTROLUMINESCENT devices have been developed recently that are based on new materials such as porous silicon1 and semiconducting polymers2,3. By taking advantage of developments in the preparation and characterization of direct-gap semiconductor nanocrystals4-6, and of electroluminescent polymers7, we have now constructed a hybrid organic/inorganic electroluminescent device. Light emission arises from the recombination of holes injected into a layer of semiconducting p-paraphenylene vinylene (PPV)8-10 with electrons injected into a multilayer film of cadmium selenide nanocrystals. Close matching of the emitting layer of nanocrystals with the work function of the metal contact leads to an operating voltage11 of only 4V. At low voltages emission from the CdSe layer occurs. Because of the quantum size effect19-24 the colour of this emission can be varied from red to yellow by changing the nanocrystal size. At higher voltages green emission from the polymer layer predominates. Thus this device has a degree of voltage tunability of colour.

  2. Synthesis of Co-Electrospun Lead Selenide Nanostructures within Anatase Titania Nanotubes for Advanced Photovoltaics

    Directory of Open Access Journals (Sweden)

    Evan K. Wujcik

    2015-06-01

    Full Text Available Inorganic nano-scale heterostructures have many advantages over hybrid organic-inorganic dye-sensitized solar cells (DSSC or Grätzel cells, including their resistance to photo-bleaching, thermal stability, large specific surface areas, and general robustness. This study presents a first-of-its-kind low-cost all-inorganic lead selenide-anatase titania (PbSe/TiO2 nanotube heterostructure material for photovoltaic applications. Herein, PbSe nanostructures have been co-electrospun within a hollow TiO2 nanotube with high connectivity for highly efficient charge carrier flow and electron-hole pair separation. This material has been characterized by transmission electron microscopy (TEM, electron diffraction, energy dispersive X-ray spectroscopy (EDX to show the morphology and material composition of the synthesized nanocomposite. Photovoltaic characterization has shown this newly synthesized proof-of-concept material can easily produce a photocurrent under solar illumination, and, with further refinement, could reveal a new direction in photovoltaic materials.

  3. New route for preparation of luminescent mercaptoethanoate capped cadmium selenide quantum dots

    Indian Academy of Sciences (India)

    Manoj E Wankhede; Shaukatali N Inamdar; Aparna Deshpande; Aniket R Thete; Renu Pasricha; Sulabha K Kulkarni; Santosh K Haram

    2008-06-01

    We report a synthesis of cadmium selenide quantum dots (Q-CdSe) by refluxing a mixture of cadmium acetate, selenium powder, sodium sulfite and 2-mercaptoethanol in N,N′-dimethyl formamide (DMF)/water solution. X-ray and electron diffractions suggest the formation of hexagonal phase of size quantized CdSe. Based on TEM analysis, the formation of nanoparticles with an average diameter of 3.5 ± 0.5 nm is inferred. Their sols in DMF and dimethyl sulphoxide (DMSO) gave characteristic absorption peaks at 300 nm and 327 nm, which is attributed to the formation of high quality, size quantized CdSe particles. Extracted particles from the sol were readily redispersed in DMF and DMSO, which were diluted further with water without losing their optical and colloidal properties. FTIR spectroscopy suggested the formation of 2-mercaptoethanol thiolate on the particle surface, with free –OH groups available for linkage. Sols in DMSO and their solutions in water displayed an intense photoluminescence (PL).

  4. Bifacial dye-sensitized solar cells with transparent cobalt selenide alloy counter electrodes

    Science.gov (United States)

    Duan, Yanyan; Tang, Qunwei; He, Benlin; Zhao, Zhiyuan; Zhu, Ling; Yu, Liangmin

    2015-06-01

    High power conversion efficiency and cost-effectiveness are two persistent objectives for dye-sensitized solar cell (DSSC). Electricity generation from either front or rear side of a bifacial DSSC has been considered as a facile avenue of bringing down the cost of solar-to-electric conversion. Therefore, the fabrication of a transparent counter electrode (CE) with a high electrocatalytic activity is a prerequisite to realize this goal. We present here the feasibility of utilizing transparent cobalt selenide (Co-Se) binary alloy counter electrode for bifacial DSSC application, in which binary Co-Se alloy electrode is synthesized by a mild solution strategy and the cell device is irradiated by either front or rear side. Due to the high optical transparency, charge-transfer ability, and electrocatalytic activity, maximum front and rear efficiencies of 8.30% and 4.63% are recorded under simulated air mass 1.5 (AM1.5) irradiation, respectively. The impressive efficiency along with fast start-up, multiple start capability, and simple preparation highlights the potential application of cost-effective and transparent Co-Se alloy CE in robust bifacial DSSCs.

  5. DFT Study on the Carrier Concentration and Temperature-Dependent Thermoelectric Properties of Antimony Selenide

    Directory of Open Access Journals (Sweden)

    Aditya Jayaraman

    2016-01-01

    Full Text Available We present the thermoelectric properties of Antimony Selenide (Sb2Se3 obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BoltzTrap code using the constant relaxation time (τ approximation at three different temperatures 300 K, 600 K, and 800 K. Seebeck coefficient (S was found to decrease with increasing temperature, electrical conductivity (σ/τ was almost constant in the entire temperature range, and electronic thermal conductivity (κ/τ increased with increasing temperature. With increase in temperature S decreased from 1870 μV/K (at 300 K to 719 μV/K (at 800 K, electronic thermal conductivity increased from 1.56 × 1015 W/m K s (at 300 K to 3.92 × 1015 W/m K s (at 800 K, and electrical conductivity decreased from 22 × 1019/Ω m s (at 300 K to 20 × 1019/Ω m s (at 800 K. The thermoelectric properties were also calculated for different hole concentrations and the optimum concentration for a good thermoelectric performance over a large range of temperatures (from 300 K to 1000 K was found for hole concentration around 1019 cm−3.

  6. Femtosecond Transient Absorption Studies in Cadmium Selenide Nanocrystal Thin Films Prepared by Chemical Bath Deposition Method

    Directory of Open Access Journals (Sweden)

    M. C. Rath

    2007-01-01

    Full Text Available Dynamics of photo-excited carrier relaxation processes in cadmium selenide nanocrystal thin films prepared by chemical bath deposition method have been studied by nondegenerate femtosecond transient pump-probe spectroscopy. The carriers were generated by exciting at 400 nm laser light and monitored by several other wavelengths. The induced absorption followed by a fast bleach recovery observed near and above the bandgap indicates that the photo-excited carriers (electrons are first trapped by the available traps and then the trapped electrons absorb the probe light to show a delayed absorption process. The transient decay kinetics was found to be multiexponential in nature. The short time constant, <1 picosecond, was attributed to the trapping of electrons by the surface and/or deep traps and the long time constant, ≥20 picoseconds, was due to the recombination of the trapped carriers. A very little difference in the relaxation processes was observed in the samples prepared at bath temperatures from 25∘C to 60∘C.

  7. A new wide band gap thermoelectric quaternary selenide Cu2MgSnSe4

    Science.gov (United States)

    Pavan Kumar, V.; Guilmeau, Emmanuel; Raveau, Bernard; Caignaert, Vincent; Varadaraju, U. V.

    2015-10-01

    Cu2MgSnSe4 based compounds composed of high earth abundant elements have been identified to exhibit good thermoelectric performance in the mid-temperature range. The pristine phase shows a band gap of 1.7 eV, which is slightly higher than similar ternary and quaternary copper based stannite compounds. Cu2MgSnSe4 crystallizes in the tetragonal I 4 ¯ 2m space group. Substitution of In at Sn site tends to decrease the tetragonal distortion toward the cubic symmetry. The electrical and thermal transport properties of Cu and In-doped Cu2MgSnSe4 in the temperature range of 300 K-700 K are studied. The substitution of In3+ for Sn4+ and Cu2+ for Mg2+ induces charge carriers as holes, which in turn lead to improvement in thermoelectric efficiency. The role of mass fluctuations and structural disorder in the evolution of the thermal conductivity of the doped selenides is discussed. A maximum ZT of 0.42 is attained for Cu2MgSn0.925In0.075Se4 around 700 K, and this value is comparable to that of Cu2ZnSnSe4.

  8. Noncentrosymmetric selenide Ba4Ga4GeSe12: Synthesis, structure, and optical properties

    Science.gov (United States)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Lin, Xinsong; Yao, Jiyong; Mar, Arthur

    2016-09-01

    The selenide Ba4Ga4GeSe12, synthesized by reaction of BaSe, Ga2Se3, and GeSe2 at 1173 K, adopts a noncentrosymmetric tetragonal structure (space group P 4 bar21 c , Z=2, a=13.5468(4) Å, c=6.4915(2) Å) consisting of a three-dimensional network built from two types of corner-sharing MSe4 tetrahedra, with Ba cations occupying the intervening voids. It is isostructural to Pb4Ga4GeS12, Pb4Ga4GeSe12, and Ba4Ga4SnSe12, but differs subtly in site ordering. Structural refinements and bond valence sum analysis suggest partial disorder manifested by mixing of 0.75 Ga and 0.25 Ge within one tetrahedral site, and occupation of exclusively Ga within the other tetrahedral site. The optical band gap of 2.18(2) eV, measured from the UV/VIS/NIR diffuse reflectance spectrum, agrees with a calculated gap of 2.35 eV between valence and conduction bands and is consistent with the orange-yellow color of the crystals. Nonlinear optical measurements on powder samples revealed a weak second harmonic generation signal using 2.09 μm as the fundamental laser wavelength.

  9. Ab-Initio Computations of Electronic and Related Properties of cubic Lithium Selenide (Li2Se)

    Science.gov (United States)

    Goita, Abdoulaye; Nwigboji, Ifeanyi H.; Malozovsky, Yuriy; Bagayoko, Diola

    We present theoretical predictions, from ab-initio, self-consistent calculations, of electronic and related properties of cubic lithium selenide (Li2Se). We employed a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). We performed the computations following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Our results include electronic energies, total and partial densities of states, effective masses, and the bulk modulus. The theoretical equilibrium lattice constant is 5.882 Å. We found cubic Li2Se to have a direct band gap of 4.363 eV (prediction), at Γ. This gap is 4.065 eV for a room temperature lattice constant of 6.017 Å. The calculated bulk modulus is 31.377 GPa. Acknowledgments: This work was funded in part by the National Science Foundation (NSF) and the Louisiana Board of Regents, through LASiGMA [Award Nos. EPS- 1003897, NSF (2010-15)-RII-SUBR] and NSF HRD-1002541, the US Department of Energy - National, Nuclear Security Administration (NNSA) (Award No. DE- NA0002630), LaSPACE, and LONI-SUBR.

  10. Layered bismuth selenide utilized as hole transporting layer for highly stable organic photovoltaics

    KAUST Repository

    Yuan, Zhongcheng

    2015-11-01

    Abstract Layered bismuth selenide (L-Bi2Se3) nanoplates were implemented as hole transporting layers (HTLs) for inverted organic solar cells. Device based on L-Bi2Se3 showed increasing power conversion efficiency (PCE) during ambient condition storage process. A PCE of 4.37% was finally obtained after 5 days storage, which outperformed the ones with evaporated-MoO3 using poly(3-hexylthiophene) (P3HT) as donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor. The improved device efficiency can be attributed to the high conductivity and increasing work function of L-Bi2Se3. The work function of L-Bi2Se3 increased with the storage time in ambient condition due to the oxygen atom doping. Ultraviolet photoelectron spectroscopy and high resolution X-ray photoelectron spectroscopy were conducted to verify the increased work function, which originated from the p-type doping process. The device based on L-Bi2Se3 exhibited excellent stability in ambient condition up to 4 months, which was much improved compared to the device based on traditional HTLs. © 2015 Elsevier B.V.

  11. An electrochemical oxidation process of Am (III) into Am (VI) used to separate the americium of spent fuels reprocessing solutions

    International Nuclear Information System (INIS)

    The aim of this invention is to oxidize by an electrochemical process Am (III) to Am (VI). This process can be used to separate the americium of spent fuels reprocessing solutions. The method consists to add to the aqueous nitric solution containing Am (III) an heteropolyanion able to complex the americium (as for instance the potassium tungstophosphate) and the Ag (II) ion. The Ag (II) ion oxidizes the Am (III) and is reduced into an Ag (I) ion. It is then regenerated by the electrolysis of the solution. After the oxidation of Am (III) into Am (VI), this last ion can be extracted by an adapted organic solvent. With this electrochemical method a yield of 100% Am (VI) is obtained in half a hour. (O.M.). 5 refs., 5 figs., 2 tabs

  12. Separation of oxidized americium from lanthanides by use of pillared metal(IV) phosphate-phosphonate hybrid materials

    International Nuclear Information System (INIS)

    Closing the nuclear fuel cycle in the US poses many challenges, one of which is found in the waste streams, which contain both trivalent lanthanides and actinides. The separation of americium from the raffinate will dramatically reduce the long-term radiotoxicity of the waste. The sorption of americium in both the tri- and pentavalent oxidation states was observed for four M(IV) phosphate-phosphonate ion exchange materials in nitric acid at pH 2. High selectivity was observed for reduced Am(III) with Kd values ca. 6 x 105 mL/g, while the Kd values for Am(V) were much lower. A new method of synthesizing and stabilizing AmO2+ to yield a lifetime of at least 24 h in acidic media using a combination of sodium persulfate and calcium hypochlorite will be described.

  13. Effects of impurities on the size and form of crystals of thorium and americium oxalates and oxides

    International Nuclear Information System (INIS)

    The influence of impurity salts and certain surfactants on the shape and size of thorium and americium oxalate crystals, as well as crystals of their dioxides, prepared at thermolysis of oxalate precipitates, has been investigated. It is shown that during thorium oxalate deposition from solutions, containing 0.8 mol/l thorium and 2 mol/l nitric acid at 96 deg C in the presence of ammonium salts or surfactants larger and monodisperse crystals are grown than in the absence of the above-mentioned substances. Addition of ammonium nitrate in the amount of 0.6 mol/l to solution containing 7.6x10-3 mol/l of americium dioxide particles coincides with the shape of oxalate crystals but their size is reduced by (20-25)% as compared with the initial ones

  14. Combined radiochemical procedure for determination of plutonium, americium and strontium-90 in the soil samples from SNTS

    International Nuclear Information System (INIS)

    The results of combined radiochemical procedure for the determination of plutonium, americium and 90Sr (via measurement of 90Y) in the soil samples from SNTS (Semipalatinsk Nuclear Test Site) are presented. The processes of co-precipitation of these nuclides with calcium fluoride in the strong acid solutions have been investigated. The conditions for simultaneous separation of americium and yttrium using extraction chromatography have been studied. It follows from analyses of real soil samples that the procedure developed provides the chemical recovery of plutonium and yttrium in the range of 50-95 % and 60-95 %, respectively. The execution of the procedure requires 3.5 working days including a sample decomposition study. (author)

  15. Extraction of americium(III) from nitric acid medium by CMPO-TBP extractants in ionic liquid diluent

    International Nuclear Information System (INIS)

    Extraction of americium(III) from nitric acid medium by a solution of tri-n-butylphosphate (TBP) and n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) in room temperature ionic liquid, l-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (bmimNTf2), was studied and the results were compared with that obtained with CMPO-TBP in n-doddecane (n-DD). The distribution ratio of 241Am(III) in TBP-CMPO/bmimNTf2 was measured as a function of various parameters such as concentrations of nitric acid, CMPO, bmimNO3, NaNO3 and TBP and temperature. Remarkably large distribution ratios were observed for the extraction of americium(III) when bmimNTf2 acted as diluent and the extraction was insignificant in the absence of CMPO. The stoichiometry of metal-solvate in organic phase was determined by the slope analysis of extraction data and it indicated the formation of 1:3 (Am: CMPO) complex in organic phase. Viscosity of TBP-CMPO/bmimNTf2 at various temperatures and enthalpy change accompanied by the extraction of americium(III) were determined and reported in this paper. (orig.)

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

    Science.gov (United States)

    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.

  17. Consideration of the effect of lymph-node deposition upon the measurement of plutonium and americium in the lungs

    International Nuclear Information System (INIS)

    Measurement of an inhaled radionuclide by external photon counting includes quantities which may be contained in lymph nodes, as well as quantities in the lungs. An overestimate of the lung burden can result, if a portion of the radionuclide were present in the lymph nodes. This problem is analyzed with respect to the measurement of inhaled plutonium containing plutonium-241 and americium-241, when americium-241 has been used as a tracer for the plutonium. Equations are derived which yield the amounts of americium and of plutonium in the lungs and in the lymph nodes as a function of time after exposure and for various translocation and retention parameters. Count histories (count profiles) of actual exposure cases are compared with calculated count profiles in order to gain insight into possible values of the translocation and retention parameters. Comparison is also made with calculated count profiles using values of translocation and retention parameters recommended by the International Commission on Radiological Protection (ICRP) for use with the Task Group Lung Model. The magnitude of the possible overestimate (error factor) was calculated for combinations o

  18. HELIOS: the new design of the irradiation of U-free fuels for americium transmutation

    Energy Technology Data Exchange (ETDEWEB)

    D' Agata, E. [European Commission, Joint Research Centre, Institute for Energy, P.O. Box 2, 1755 ZG Petten (Netherlands); Klaassen, F.; Sciolla, C. [Nuclear Research and Consultancy Group, Dept. Life Cycle and Innovations, P.O. Box 25 1755 ZG Petten (Netherlands); Fernandez-Carretero, A. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Bonnerot, J.M. [Commissariat a l' Energie Atomique, DEC/SESC/LC2I CEA-Cadarache, 13108 St. Paul lez Durance Cedex (France)

    2009-06-15

    Americium is one of the radioactive elements that mostly contribute to the radiotoxicity of the nuclear spent fuel. Transmutation of long-lived nuclides like Americium is an option for the reduction of the mass, the radiotoxicity and the decay heat of nuclear waste. The HELIOS irradiation experiment is the last evolution in a series of experiments on americium transmutation. The previous experiments, EFTTRA-T4 and T4bis, have shown that the release or trapping of helium is the key issue for the design of such kind of target. In fact, the production of helium, which is characteristic of {sup 241}Am transmutation, is quite significant. The experiment is carried out in the framework of the 4-year project EUROTRANS of the EURATOM 6. Framework Programme (FP6). Therefore, the main objective of the HELIOS experiment is to study the in-pile behaviour of U-free fuels such as CerCer (Pu, Am, Zr)O{sub 2} and Am{sub 2}Zr{sub 2}O{sub 7}+MgO or CerMet (Pu, Am)O{sub 2}+Mo in order to gain knowledge on the role of the fuel microstructure and of the temperature on the gas release and on the fuel swelling. The experiment was planned to be conducted in the HFR (High Flux Reactor) in Petten (The Netherlands) starting the first quarter of 2007. Because of the innovative aspects of the fuel, the fabrication has had some delays as well as the final safety analyses of the original design showed some unexpected deviation. Besides, the HFR reactor has been unavailable since August 2008. Due to the reasons described above, the experiment has been postponed. HELIOS should start in the first quarter of 2009 and will last 300 full power days. The paper will cover the description of the new design of the irradiation experiment HELIOS. The experiment has been split in two parts (HELIOS1 and HELIOS2) which will be irradiated together. Moreover, due to the high temperature achieved in cladding and to the high amount of helium produced during transmutation the experiment previously designed for a

  19. Uptake of americium-241 by plants from contaminated Chernobyl exclusive zone test site soils

    International Nuclear Information System (INIS)

    Americium-241 was found to accumulate in soils and biological objects of the environment. Its concentration has increased many times after the Chernobyl disaster and can be expected to increase about 40 times in the future. This research concentrated on the contaminated exclusive Chernobyl zone polluted by trace radionuclides, their behavior and accumulation by various plant species. Special attention is devoted to the bioavailability of 241Am to the plants Galium rivale, G. tinctorium, G. aparine, G. intermedium, Berteroa incana, Artemisia absinthium, A. vulgaris, Centaurea borysthenica, C. arenaria, Cirsium arvense, Succissa pratensis, Solidago virgaurea, Linaria vulgaris, Lepidium ruderale, Stenactis annua, Veronica maxima, Verbascum lychnitis, Euphorbia cyparissias, Genista tinctoria, Erigeron canadensis, Oenothera biennis, Betula pendula and Quercus robur, which were collected from the Chernobyl, Kopachi, and Yanov districts. The plant samples of Oenothera biennis, Betula pendula and Quercus robur were collected from the Yanov district, where the soil contamination by 241Am and 137Cs was at the level of 660 and 27 MBq/m2, respectively. Gamma spectroscopy and radiochemical methods were used to estimate the activity concentration of 137Cs, 90Sr, 238Pu, 239+240Pu, 241Am. The radionuclides were measured in the dry green mass of the plant samples and in the dry soils. The contamination of the Oenothera biennis, Betula pendula and Quercus robur samples by 137Cs was (5.8±1,5)x106, (7.4±1.1)x105, and (2.6±0.2)x106 Bq/kg dry mass, respectively, and contamination by 241Am was 47±5, 45±3 and 3.2±0.2 Bq/kg, respectively. The soil-to-plant transfer ratio for 137Cs ranged lay within the interval of 0.2 to 0.03 Bq/kg : Bq/m2, the the transfer ratio for 241Am did not exceed 7x10-5 Bq/kg : Bq/m2. The coefficient of the relative contents of the 241Am/239+240Pu radionuclides in the various plant samples varied from 3.2 to 8.3, while for soil from the Yanov district this

  20. Anomalous aryl strengthening of complexes at americium and europium extraction with alkylenediphospine dioxide from perchloric media

    International Nuclear Information System (INIS)

    Studied was the extraction of americium(3) and europium(3) from perchlorate solutions(0.001 M) with dioxides of alkylenediphosphines of three types: aryl Ph2P(O)CH2(O)PPh2(briefly 4P), and Ph2P(O)(CH2)2(O)PPh2, mixed Ph2P(O)CH2(O)P(C8H17)2 (or 2Ph2Oct) and alkyl (C8H17)2P(O)CH2(O)P(C8H17)2 (or 4 Oct). Trisolvates of MeS3x(ClO4)3 are predominantly formed but americium disolvates are also present upon dilution with dichloroethane. For 4Ph,2Ph2Oct and 4 Oct the concentration is, respectively, 1015, 2x1014, and 1013; for disolvates by 4 orders of magnitude lower which is, nevertheless, by 2 orders of magnitude higher than for nitric acid solutions. The separation coefficient of β Am/Eu for 4Ph attains 6-8. As in the case of nitrate solutions, an anomalous aryl strengthening of the complexes is observed: an increase in the distribution coefficients and extraction constants in the series of 4 Oct - 2Ph 2 Oct - 4Ph, in spite of the introduction of electronegative aryl substituents into the dioxide molecule, which reduce electron density on oxygen atoms and basicity of dioxides. In contrast to nitric acid solutions, observed is a nonlinear effect of a change in basicity on extraction properties upon dilution with dichloroethane (dioxide of 2Ph2 Oct does not occupy an intermediate position but is close to 4Ph). Upon dilution with chloroform the dependence is linear and anomalous effect rises due to a different nature of interactions of dioxides with chloroform. When the bridge increases up to ethylene, an anomalous strengthening of the complexes disappears. However, the distribution coefficients upon extraction with alkyl dioxide are considerably lower, which can be explained by a stronger extraction of perchloric acid

  1. Self-standing nanoribbons of antimony selenide and antimony sulfide with well-defined size and band gap

    Energy Technology Data Exchange (ETDEWEB)

    Vadapoo, Rajasekarakumar; Krishnan, Sridevi; Yilmaz, Hulusi [Department of Physics, University of Puerto Rico, San Juan, PR 00936 (Puerto Rico); Marin, Carlos [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States)

    2011-04-29

    Sub-10 nm semiconducting nanostructures are crucial for the realization of nanoscale devices. Fabrication of nanostructures at this scale with homogeneous properties is challenging. Using ab initio calculations, we show that self-standing ribbons of antimony selenide and antimony sulfide of width 1.1 nm exhibit well-defined bandgaps of 1.66 and 2.16 eV, respectively. Molecular dynamics studies show that these ribbons are stable at 500 K. The one-dimensional (1D) heterostructure of these nanoribbons (Sb{sub 2}Se{sub 3}/Sb{sub 2}S{sub 3}) along the [001] direction shows a straddling type behavior.

  2. The Non-Isotypical Nitride Selenides Dy3NSe3 and Ho3NSe3: Chains and Dimers

    OpenAIRE

    Lissner, Falk; Schleid, Thomas

    2009-01-01

    Abstract The non-isotypical lanthanoid(III) nitride selenides M3NSe3 of dysprosium (Dy3NSe3) and holmium (Ho3NSe3) are formed by the reaction of the respective rare-earth metal (M = Dy and Ho) with sodium azide (NaN3), selenium and an excess of iodine at 900 ?C from torch-sealed evacuated silica ampoules within seven days. Dy3NSe3 crystallizes orthorhombically (a = 1245.38(9), b = 393.69(3), c = 1303.74(9) pm) in space group Pnma with Z = 4, whereas monoclinic Ho3NSe3 (a = 1152.93(...

  3. Vacancies ordered in screw form (VOSF) and layered indium selenide thin film deposition by laser back ablation

    International Nuclear Information System (INIS)

    Indium selenide thin films are important due to their applications in non-volatile memory and solar cells. In this work, we present an initial study of a new application of deposition-site selective laser back ablation (LBA) for making thin films of In2Se3. Invacuo annealing and subsequent characterization of the films by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that control of substrate temperature during deposition and post-deposition annealing temperature is critical in determining the phase and composition of the films. The initial laser fluence and target film thickness determine the amount of material deposited onto the substrate.

  4. Fluorescence imaging technology (FI) for high-throughput screening of selenide-modified nano-TiO2 catalysts.

    Science.gov (United States)

    Wang, Liping; Lee, Jianchao; Zhang, Meijuan; Duan, Qiannan; Zhang, Jiarui; Qi, Hailang

    2016-02-18

    A high-throughput screening (HTS) method based on fluorescence imaging (FI) was implemented to evaluate the catalytic performance of selenide-modified nano-TiO2. Chemical ink-jet printing (IJP) technology was reformed to fabricate a catalyst library comprising 1405 (Ni(a)Cu(b)Cd(c)Ce(d)In(e)Y(f))Se(x)/TiO2 (M6Se/Ti) composite photocatalysts. Nineteen M6Se/Tis were screened out from the 1405 candidates efficiently. PMID:26777131

  5. Analysis on the Performance of Copper Indium Gallium Selenide (CIGS Based Photovoltaic Thermal

    Directory of Open Access Journals (Sweden)

    Zulkepli Afzam

    2016-01-01

    Full Text Available This paper deals with the efficiency improvement of Copper Indium Gallium Selenide (CIGS Photovoltaic (PV and also solar thermal collector. Photovoltaic thermal (PV/T can improve overall efficiency for PV and also solve the problem of limited roof space at urban area. Objective of this study is to clarify the effect of mass flow rate on the efficiency of the PV/T system. A CIGS solar cell is used with rated output power 65 W and 1.18 m2 of area. 4 set of experiments were carried out, which were: thermal collector with 0.12 kg/s flow rate, PV/T with 0.12 kg/s flow rate, PV/T with 0.09 kg/s flow rate and PV. It was found that PV/T with 0.12 kg/s flow rate had the highest electrical efficiency, 2.92 %. PV/T with 0.09 kg/s flow rate had the lowest electrical efficiency, 2.68 %. It also had 2 % higher overall efficiency. The efficiency gained is low due to several factors. The rated output power of the PV is low for the area of 1.18 m2. The packing factor of the PV also need to be considered as it may not be operated at the optimal packing factor. Furthermore, aluminium sheet of the PV may affect the PV temperature due to high thermal conductivity. Further study on more values of mass flow rate and also other parameters that affect the efficiency of the PV/T is necessary.

  6. Formation of dimethyl selenide and trimethylselenonium from selenobetaine in the rat

    International Nuclear Information System (INIS)

    The 24-h respiratory excretion of dimethyl selenide (DMSe) and urinary excretion of trimethylselenonium (TMSe) were studied in adult male rats injected with 2 mg Se/kg as selenobetaine [(CH3)2Se+CH2COOH] or its methyl ester, labeled with 75Se and 14C. The DMSe was trapped by means of 20% benzyl chloride in xylene. TMSe was measured by cation exchange high performance liquid chromatography. There was extensive respiratory excretion of DMSe from selenobetaine methyl ester (about 50% of the dose) and from selenobetaine (about 25%). About 12% of the dose was converted to TMSe for both compounds. When the Se-methyl carbons were labeled with 14C and the selenium with 75Se, doubly labeled DMSe and TMSe were formed; the 14C/75Se ratio in DMSe formed from selenobetaine methyl ester was almost unchanged from that administered, and the ratio in TMSe was only slightly lower than in DMSe. In contrast to its ester, doubly labeled selenobetaine yielded DMSe having a lower 14C/75Se ratio (approximately one-half of that administered) and a further decrease was observed between DMSe and TMSe. These data indicate that the (CH3)2Se moiety in selenobetaine methyl ester undergoes facile release to form DMSe, which is directly methylated to form TMSe. Selenobetaine, however, appears to lose a methyl group prior to scission of the Se-CH2COOH bond. The results with selenobetaine also suggest that TMSe generated metabolically is not inert, and can undergo demethylation followed by remethylation; confirmatory evidence for this metabolic instability is provided by the exhalation of [75Se]DMSe after the direct administration of [75Se]TMSe. When [75Se]selenobetaine or its ester was given with the methylene carbon in the acetic acid molabeled with 14C, only 75Se was present in the DMSe and TMSe

  7. Exploring the doping effects of copper on thermoelectric properties of lead selenide

    Science.gov (United States)

    Gayner, Chhatrasal; Sharma, Raghunandan; Mallik, Iram; Das, Malay K.; Kar, Kamal K.

    2016-07-01

    In this work, we have explored the effect of dopant concentration (copper (Cu)) on the thermoelectric performance of Cu doped lead selenide (Pb1‑x Cu x Se (0  ⩽  x  ⩽  0.1)). With increasing the dopant concentration, sign inversion of majority charge carriers takes place for x  ⩾  0.04 due to the donor behaviour of Cu in the P-type pristine PbSe. The room temperature Seebeck coefficients of Pb1‑x Cu x Se with x  =  0.01, 0.02, 0.04, 0.06 and 0.08 are observed to be 233, 337, ‑473.7, ‑392.5 and  ‑257.6 μV K‑1, respectively as compared to that of 186.4 μV K‑1 of the pristine PbSe. This increment in Seebeck coefficient is the result of low carrier concentration and is not related to the resonance states created by Cu dopant. At room temperature, the lattice thermal conductivity of pristine PbSe is 0.52 W m‑1 K‑1 while for Cu doped PbSe, it varies from 0.8 to 1.1 W m‑1 K‑1. Finally, with ZT of ~0.59 and power factor of ~700 at 500 K, Pb0.98Cu0.02Se exhibits the highest thermoelectric performance among the studied Pb1‑x Cu x Se systems. Owing to the high ZT and power factor, a single thermoelement of Pb0.98Cu0.02Se exhibits thermovoltage of  >100 mV at a temperature gradient of 200 °C.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Horlait, Denis; Lebreton, Florent [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze (France); Gauthé, Aurélie [CEA, DEN, DRCP/SERA/LCAR, 30207 Bagnols-sur-Cèze (France); Caisso, Marie [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze (France); Arab-Chapelet, Bénédicte; Picart, Sébastien [CEA, DEN, DRCP/SERA/LCAR, 30207 Bagnols-sur-Cèze (France); Delahaye, Thibaud, E-mail: thibaud.delahaye@cea.fr [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze (France)

    2014-01-15

    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 U{sub 0.85}Am{sub 0.15}O{sub 2±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.

  10. Influence of organic additives on the colour reaction between trivalent americium and arsenazo III

    International Nuclear Information System (INIS)

    The colour reaction of Am(III) with arsenazo III in several hydroorganic media has been examined systematically on the addition of certain polar water-miscible organic solvents in the course of a search for improved and simple spectrophotometric methods for the estimation of americium. Addition of these substances resulted in the stabilization of colour and brought about a drastic enhancement in the absorbance values. The organic additives studied include acetone, acetonitrile, dimethylformamide, dioxane and ethanol. Among the many solvents tested, alcohol and dioxane proved to be the most effective, the highest sensitivity is obtained by using a 60% dioxane-ethanol (1:1) mixture. The apparent molar absorptivity based on Am content is 184616+-9931 mol-1 cm-1 at 655 nm which is about 3 times higher than that attained for the reaction in aqueous medium (65178+-1243). Moreover, this is the highest value reported as yet for its determination. Beer's law is obeyed both in mixed and aqueous media. The effects of some experimental variables on colour development have also been studied to optimize the conditions for the assay of Am. (author)

  11. Speciation and bioavailability of Americium-241 in the fresh water environment

    International Nuclear Information System (INIS)

    Due to its anthropogenic origin, the transuranic americium 241 confronts physiologists with the intriguing question, which mechanisms are involved in the incorporation or elimination of such artificial elements in biological cycles. The investigations on the speciation and bioavailability of 241Am in the freshwater environment aim to establish a relation between the behavior of 241Am in freshwater ecosystems and its availability for biota. In the limnic environment, most often characterized by a high organic load and a low conductivity, the effect of complexation of 241Am with humic acids and competition with trivalent cations such as A1 and Fe, were proven to be significant on the speciation of 241Am. Based on the registration of the 241Am uptake by a large number of freshwater organisms, the crayfish Astacus leptodactylus Eschscholtz was chosen to study the whole-body uptake of 241Am, its corresponding organ distribution and its retention in the animal. The share of external fixation and ingestion in the global uptake, and the effect of speciation on it, were studied more carefully. Other aspects in this physiological part were: the kinetics of 241Am in the hemolymph and the hepatopancreas, and its subcellular distribution in the digestive gland. Finally, by comparing the physiology of 241Am with some other metals (240Pu, 64Cu, 198Au) with analogous or contradictional properties, we tried to find out whether the behavior of 241Am in organisms can be explained from its chemical characteristics

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Determination of plutonium americium and curium in soil samples by solvent extraction with trioctylphosphine oxide

    International Nuclear Information System (INIS)

    A method of Pu, Am and Cm determination in soil samples, which was developed for analyzing samples from territories subjected to radioactive contamination as a result of the Chernobyl accident is described. After preliminary treatment the samples were leached by solution of 7 mol/l HNO23+0.3 mol/l KBrO3 during heating. Pu was isolated by extraction with 0.05 mol TOPO from 7 mol/l HNO3. 144Ce and partially remaining in water phase isotopes of Zr, U and Th were isolated in an extraction-chromatographic column with TOPO and PbO2. Then Am and Cm were extracted by 0.2 mol/l TOPO from solution 1 mol/l HLact+0.07 mol/l DTPA+1 mol/l Al(NO3)3. Alpha-activity of both extracted products was determined in liquid scintillation counter. Chemical yield of plutonium counted to 85±10%, that of americium and curium -75±10%. 17 refs

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

    International Nuclear Information System (INIS)

    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 μCi) 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 μrem) 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 μSv (0.0006 to 8 mrem) to total body and from 0.06 to 800 μSv 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

  15. NMR Evidence for the 8.5 K Phase Transition in Americium Dioxide

    Science.gov (United States)

    Tokunaga, Yo; Nishi, Tsuyoshi; Kambe, Shinsaku; Nakada, Masami; Itoh, Akinori; Homma, Yoshiya; Sakai, Hironori; Chudo, Hiroyuki

    2010-05-01

    We report here the first NMR study of americium dioxide (AmO2). More than 30 years ago, a phase transition was suggested to occur in this compound at 8.5 K based on magnetic susceptibility data, while no evidence had been obtained from microscopic measurements. We have prepared a powder sample of 243AmO2 containing 90 at. % 17O and have performed 17O NMR at temperatures ranging from 1.5 to 200 K. After a sudden drop of the 17O NMR signal intensity below 8.5 K, at 1.5 K we have observed an extremely broad spectrum covering a range of ˜14 kOe in applied field. These data provide the first microscopic evidence for a phase transition as a bulk property in this system. In addition, the 17O NMR spectrum has been found to split into two peaks in the paramagnetic state, an effect which has not been reported for actinide dioxides studied up to now. We suggest that the splitting is induced by self-radiation damage from the alpha decay of 243Am.

  16. Study of biosorbents application on the treatment of radioactive liquid wastes with americium-241

    International Nuclear Information System (INIS)

    The use of nuclear energy for many different purposes has been intensified and highlighted by the benefits that it provides. Medical diagnosis and therapy, agriculture, industry and electricity generation are examples of its application. However, nuclear energy generates radioactive wastes that require suitable treatment ensuring life and environmental safety. Biosorption and bioaccumulation represent an emergent alternative for the treatment of radioactive liquid wastes, providing volume reduction and physical state change. This work aimed to study biosorbents for the treatment of radioactive liquid wastes contaminated with americium-241 in order to reduce the volume and change the physical state from liquid to solid. The biosorbents evaluated were Saccharomyces cerevisiae immobilized in calcium alginate beads, inactivated and free cells of Saccharomyces cerevisiae, calcium alginate beads, Bacillus subtilis, Cupriavidus metallidurans and Ochrobactrum anthropi. The results were quite satisfactory, achieving 100% in some cases. The technique presented in this work may be useful and viable for implementing at the Waste Management Laboratory of IPEN - CNEN/SP in short term, since it is an easy and low cost method. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

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

    2014-09-01

    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. PMID:25126837

  19. Comparative study of plutonium and americium bioaccumulation from two marine sediments contaminated in the natural environment

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, T.F.; Smith, J.D. (Melbourne Univ., Parkville (Australia). Dept. of Inorganic Chemistry); Fowler, S.W.; LaRosa, J.; Holm, E. (International Atomic Energy Agency, Monaco-Ville (Monaco). Lab. of Marine Radioactivity); Aarkrog, A.; Dahlgaard, H. (Risoe National Lab., Roskilde (Denmark))

    1991-01-01

    Plutonium and americium sediment-animal transfer was studied under controlled laboratory conditions by exposure of the benthic polychaete Nereis diversicolor (O. F. Mueller) to marine sediments contaminated by a nuclear bomb accident (near Thule, Greenland) and nuclear weapons testing (Enewetak Atoll). In both sediment regimes, the bioavailability of plutonium and {sup 241}Am was low, with specific activity in the tissues <1% (dry wt) than in the sediments. Over the first three months, a slight preference in transfer of plutonium over {sup 241}Am occurred and {sup 241}Am uptake from the Thule sediment was enhanced compared to that from lagoon sediments of Enewetak Atoll. Autoradiography studies indicated the presence of hot particles of plutonium in the sediments. The results highlight the importance of purging animals of their gut contents in order to obtain accurate estimates of transuranic transfer from ingested sediments into tissue. It is further suggested that enhanced transuranic uptake by some benthic species could arise from ingestion of highly activity particles and organic-rich detritus present in the sediments. (author).

  20. Growth and evaluation of nonlinear optical crystals for laser applications: Lithium borate, barium borate and silver gallium selenide

    Science.gov (United States)

    Feigelson, Robert S.; Route, Roger K.

    1994-12-01

    This report summarizes a four year program on the development of high efficiency nonlinear optical materials. Major achievements were the development of effective top-seeded solution growth techniques for beta-barium borate (BBO) and lithium triborate (LBO). BBO crystals were also grown for the first time in the US by the direct melt growth technique, a metastable method that leads to significantly higher growth rates than the commercial solution-growth technique. High quality crystals were made available for optical property determinations and nonlinear optical device development at government and commercial laboratories. Additional accomplishments involved development of an optimum heat-treatment technology for eliminating optical scattering centers from as-grown crystals of silver gallium selenide. Cooperative programs were carried out with NRL to quantify the effects of intrinsic and extrinsic defects on residual absorption. It was discovered that silver gallium selenide and silver gallium sulfide crystals grown from silver-rich solutions are free of anomolous absorption in the 2 micron waveband which is currently the major problem limiting generation of high intensity, tunable 3-5 micron radiation by OPO methods using these materials. A new nonlinear optical material, (La,Gd)Sc3(BO3)4 has been identified for future study.

  1. Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

    Science.gov (United States)

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Leisch, Jennifer; Taylor, Matthew; Stanbery, Billy J.

    2011-09-20

    Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

  2. A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers

    NARCIS (Netherlands)

    Xu, M.; Wachters, A.J.H.; Deelen, J. van; Mourad, M.C.D.; Buskens, P.J.P.

    2014-01-01

    We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIG

  3. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Torres, Marcos R. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Velez, Christian; Zayas, Beatriz [Universidad Metropolitana, ChemTox Laboratory, School of Environmental Affairs (United States); Rivera, Osvaldo [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Arslan, Zikri [Jackson State University, Department of Chemistry (United States); Gonzalez-Vega, Maxine N. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo [University of Puerto Rico, Molecular Science Research Center (United States); Primera-Pedrozo, Oliva M., E-mail: oprimera1@suagm.edu [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States)

    2015-06-15

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd{sup 2+}]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to

  4. Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

    International Nuclear Information System (INIS)

    Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd2+]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate

  5. Use of radioisotopes in the study of tetracycline analytical application. Extraction of compounds formed between tetracycline and neptunium and americium elements

    International Nuclear Information System (INIS)

    The behavior of tetracycline as complexing agent, in solvent extraction studies of neptunium and americium, using benzyl alcohol as the organic phase, is presented. By using radioactive tracers of 239Np and 241Am the extraction percent of these elements were determined as a function of pH in the absence and in the presence of several masking agents. The influence of shaking time and the use of different types of supporting eletrolytes upon the extraction behavior was also studied. The extraction curves obtained using EDTA as masking agent show that tetracycline can be used for neptunium and americium separation. In this condition neptunium is extracted into the organic phase and americium remains in the aqueous phase. (Author)

  6. Sorption of plutonium and americium on repository, backfill and geological materials relevant to the JNFL low-level radioactive waste repository at Rokkasho-Mura

    International Nuclear Information System (INIS)

    An integrated program of batch sorption experiments and mathematical modeling has been carried out to study the sorption of plutonium and americium on a series of repository, backfill and geological materials relevant to the JNFL low-level radioactive waste repository at Rokkasho-Mura. The sorption of plutonium and americium on samples of concrete, mortar, sand/bentonite, tuff, sandstone and cover soil has been investigated. In addition, specimens of bitumen, cation and anion exchange resins, and polyester were chemically degraded. The resulting degradation product solutions, alongside solutions of humic and isosaccharinic acids were used to study the effects on plutonium sorption onto concrete, sand/bentonite and sandstone. The sorption behavior of plutonium and americium has been modeled using the geochemical speciation program HARPHRQ in conjunction with the HATCHES database

  7. Biosorption of Americium-242 by saccharomyces cerevisiae: preliminary evaluation and mechanism

    International Nuclear Information System (INIS)

    As an important radioisotope in nuclear industry and other fields, americium-241 is one of the most serious contamination concerns duo to its high radiation toxicity and long half-life. In this experiment, the biosorption of 241Am from solution by a fungus, Saccharomyces cerevisiae (S. cerevisiae), and the effects of various experimental conditions on the biosorption and the mechanism were explored. The preliminary results showed that S. cerevisiae is a very efficient biosorbent. An average of more than 99% of the total 241Am could be removed by S. cerevisiae of 2.1g/L (dry weight) from 241Am solutions of 2.22MBq/L -555 MBq/L (Co). The adsorption equilibrium was achieved within 1 hour and the optimum pH ranged 1-3. The culture times of more than 16 hours were suitable and the efficient adsorption of 241Am by the S. cerevisiae could be noted. The biosorption of 241Am by the decomposed cell wall, protoplasm or cell membrane of S. cerevisiae was same efficient as by the intact fungus, but the some components of S. cerevisiae, such as protein and acylation group had obvious effect on adsorption. When the concentrations of coexistent Eu3+, Nd3+ were 100 times more than that of 241Am, the adsorption rates would drop to 65%. However, most of the investigated acidic ions have no significant influence on the 241Am adsorption but minute change of pH value, while the saturated EDTA can strong inhibit the biosorption of 241Am.. (authors)

  8. Characterization of uranium, plutonium, neptunium, and americium in HLW supernate for LLW certification

    International Nuclear Information System (INIS)

    The 1S Manual requires that High Level Waste (HLW) implement a waste certification program prior to sending waste packages to the E-Area vaults. To support the waste certification plan, the HLW supernate inventory of uranium, plutonium, neptunium and americium have been characterized. This characterization is based on the chemical, isotopic and radiological properties of these elements in HLW supernate. This report uses process knowledge, solubility data, isotopic inventory data and sample data to determine if any isotopes of the aforementioned elements will exceed the minimum reportable quantity (MRQ) for waste packages contaminated with HLW supernate. If the MRQ can be exceeded for a particular nuclide, then a method for estimating the waste package content is provided. Waste packages contaminated from HLW supernate do not contain sufficient U-233, U-234, U-235, U-236, U-238, Pu-239, Pu-240, Pu-241, Pu-242 or Am-241 to warrant separate reporting on the shipping manifest. Calculations show that, on average, more than 100 gallons of supernate is required to exceed the PAC (package acceptance criteria) for each of these nuclides. Thus it is highly unlikely that the PAC would be exceeded for these nuclides and unlikely that the MRQ would be exceeded. These nuclides should be manifested as zero for waste packages contaminated with HLW supernate. The only actinide isotopes that may exceed the MRQ are Np-237 and Pu-238. The recommended method to calculate the amount of these two isotopes in waste packages contaminated with HLW supernate is to ratio them to the measured Cs-137 activity

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

    International Nuclear Information System (INIS)

    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 bio-effects. Radiat. Prot. Dosim. 105(1-4), 185-187 (2003)] and the long-term follow-up of cases of inhalation intake [Malatova, I., Foltanova, S., Beckova, V., Filgas, R., Pospisilova, H. and Hoelgye, 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. (authors)

  10. The treatment of liquid radioactive waste containing Americium by using a cation exchange method

    International Nuclear Information System (INIS)

    A research in the treatment of a liquid radioactive waste containing americium has been done. The liquid radioactive waste used in this research was standard solution of U dan Ce with the initial activity of 100 ppm. The experimental investigation is aimed at a study of the effects of the waste pH, the column dimension of IR-120 cation exchanger which is expressed as L/D, the flow rate of a liquid waste and the influence of thiocyanate as a complex agent against the efficiency of a decontamination for uranium and cerium element. The experiment was done by passing downward the feed of uranium and cerium solution into an IR-120 type of cation exchanger with the L/D of 11.37. From the experimental parameters done in this research where the influence of waste pH was varied from 3 - 8, the geometric column (L/D) 11.37, the liquid flow rate was from 2.5 - 10 ml/m and the thiocyanate concentration was between 100 ppm-500 ppm can be concluded that the optimum operational condition for the ion exchange achieved were the waste pH for uranium = 4 and the waste pH for cerium = 6, the flow rate = 2.5 ml/men. From the given maximum value of DF for uranium = 24 (DE = 95.83%) and of DF for cerium = 40 (DE = 97.5%), it can also be concluded that this investigation is to be continued in order that the greater value of DF/DE can be achieved

  11. A study of plutonium and americium concentrations in seaspray on the southern Scottish coast

    International Nuclear Information System (INIS)

    Seaspray and seawater have been collected from the southern Scottish coast and, for comparison, Cumbria in northwest England during 1989 and 1991. The occurrence of sea-to-land transfer of the actinides plutonium and americium in seaspray was observed on these coasts using muslin screens (a semi-quantitative technique most efficient for collecting large spray droplets) and high volume conventional air samplers. The actinides and fine particulate in the spray were present in relatively higher concentrations than measured in the adjacent seawater, i.e. the spray was enriched in particulate actinides. The net efficiency of the muslim screens in collecting airborne plutonium isotopes and 241Am generally appeared to be about 20%. A review of earlier published concentrations of 239+240Pu and 241Am measured in aerosol and deposition for over a year several tens of metres inland was carried out. This suggested that airborne activities are up to a factor of 5 times higher in Cumbria than southern Scotland. However, neither the new data collected in 1989 and 1991 nor this older data suggests any enhancement of seaspray actinide enrichment in southern Scotland compared to Cumbria. This finding contrasts with earlier, more limited, comparisons that have been carried out which suggested such a difference. There is clear evidence of considerable localised spatial and temporal variability in aerosol actinide enrichment over the beaches in both areas. Enrichments varies between 20 and 500 relative to the adjacent surf zone waters. However, the average enrichment in spray based on the continuous measurements made further inland is likely to be at the lower end of this range. (author)

  12. Reduction of. systematic error of In-vivo measurement of americium 241 activity in the skull

    International Nuclear Information System (INIS)

    Excretion analysis and in vivo measuring methods are used for estimation of internal contamination by 241Am. In vivo measurements of the lung are suitable in short time after time of intake when the way of the intake is inhalation. In vivo measurements of the activity in the liver or in the skeleton could be performed at a later time. Detection of radionuclide activity in the liver is quite difficult because it is necessary to distinguish liver activity from the activity of surrounding tissues i.e. lung and skeleton. The skull or knees are the most suitable., for activity assessment in the skeleton. The skull is the most appropriate for measurements because it represents about 15% of total skeleton mass and contributions to measured activity of surrounding tissues are small. Americium activity in the skull could be measured with different instrumentation and in various geometries. Setting of two semiconductors detectors placed 3 cm over temporal region of the skull is used in NRPI. Calibration of the system was done by several head phantoms, in this process was observed that detection efficiencies depend on size of the phantoms. The aim of the paper is to express character of the efficiency as function of the size of skull in order to obtain more accurate value of the activity and decrees its uncertainty. Simulations of head by simplified geometric shapes, i.e. spheres and rotary ellipsoids, is in coherence with phantoms of big size (UCIN, BPAM-0001), but for small phantoms occurred quite serious discrepancy. Activity of real cases determined by calibration with phantom BPAM-0001 (reference phantom) is reduced from 9 to 44 %, when eq. 2 is used and relative uncertainty is reduced from 32% to maximum 12%. (authors)

  13. Transport of plutonium, americium, and curium from soils into plants by roots

    International Nuclear Information System (INIS)

    For assessing the dose from radionuclides in agricultural products by ingestion it is necessary to know the soil to plant transfer factors. The literature was entirely investigated, in order to judge the size of the soil to plant transfer factors. In total, 92 publications - from 1948 to 1978 -have been evaluated. As result, transfer factors from 10-9 to 10-3 have been found for Plutonium, and from 10-6 to 1 for Americium. For Curium only few data are available in literature. The considerable variation of the measured transfer factors is based on the dependence of these transfer factors from the ion exchange capacity of soils, from the amount of organic materials, from the pH-value, and from the mode of contamination. There are, in any case, contradictory data, although there has been detected a dependence of the transfer factors from these parameters. Chelating agenst increase the transfer factors to approximately 1300. As well, fertilizers have an influence on the size of the transfer factors - however, the relationships have been scarcely investigated. The distribution of actinides within the individual parts of plants has been investigated. The highest concentrations are in the roots; in the plant parts above ground the concentration of actinides decreases considerably. The most inferior transfer factors were measured for the respective seed or fruits. The soil to plant transfer factors of actinides are more dependend on the age of the plants within one growing period. At the beginning of the period, the transfer factor is considerably higher than at the end of this period. With respect to plants with a growing period of several years, correlations are unknown. (orig.)

  14. Inert matrices, uranium-free plutonium fuels and americium targets. Synthesis of CAPRA, SPIN and EFTTRA studies

    International Nuclear Information System (INIS)

    A first selection of inert-matrix materials, actinide support alone (Pu and Am based), and compound materials, U free plutonium burning fuels and heterogeneous americium targets are discussed. Basic properties, fabrication, and reprocessing studies, European in-pile and out-of-pile tests, performed recently in the framework of CAPRA, SPIN and EFTTRA programs, are reviewed here. Taking into account these studies and on the bases of the different requirements to be met in each of the fuels and targets, a number of materials have been selected as 'promising candidates'. Trends for further research on these materials are established. (author)

  15. Final Report on the Demonstration of Disposal of Americium and Curium Legacy Material Through the High Level Waste System

    International Nuclear Information System (INIS)

    This report provides the results of experimental demonstrations related to processing of a legacy solution containing americium and curium through the High Level Waste (HLW) system. The testing included eight experiments covering the baseline, mitigation, and enhanced nitrate processing studies. In general, each experiment studied the mixtures generated over a period of time to emulate the lifecycle of actual sludge in the High Level Waste system. While the data in previous reports remain valid, this report supercedes all the previous reports and provides a collective overview of the work

  16. Effect of a long-term release of plutonium and americium into an estuarine and coastal sea ecosystem

    International Nuclear Information System (INIS)

    This paper discusses the general problem of speciation of plutonium and americium in aquatic ecosystems and the implications relative to their fate in those systems. The following conclusions were reached: several oxidation states of plutonium coexist in the natural environment; the effect of environmental changes such as pH and Esub(h) values and complexes are probably the cause of these various oxidation states; a clearer definition of the 'concentration factor' should be given in view of the important role the sediments play in supplying plutonium for transfer through the food web. (author)

  17. Microstructure and elemental distribution of americium-containing MOX fuel under the short-term irradiation tests

    International Nuclear Information System (INIS)

    In order to investigate the effect of americium addition to MOX fuels on the irradiation behavior, the 'Am-1' program is being conducted in JAEA. The Am-1 program consists of two short-term irradiation tests of 10-minute and 24-hour irradiations and a steady-state irradiation test. The short-term irradiation tests were successfully completed and the post irradiation examinations (PIEs) are in progress. The PIEs for Am-containing MOX fuels focused on the microstructural evolution and redistribution behavior of Am at the initial stage of irradiation and the results to date are reported. (author)

  18. Evolution of the chemical bonding nature and electrode activity of indium selenide upon the composite formation with graphene nanosheets

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: • In4Se2.85@graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In4Se2.85 is notably changed upon the composite formation with graphene. • In4Se2.85@graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In4Se2.85@graphene and In4Se2.85@carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In4Se2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In4Se2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In4Se2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In4Se2.85. Both the nanocomposites of In4Se2.85@graphene and In4Se2.85@carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In4Se2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In4Se2.85@graphene nanocomposite is superior to that of the In4Se2.85@carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In4Se2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence on the chemical bonds and electrode activity of indium

  19. Development of a methodology for the determination of americium and thorium by ICP-AES and their inter-element effect

    International Nuclear Information System (INIS)

    Due to the scarcity of good quality uranium resources, the growth of nuclear technology in India is dependent on the utilization of the vast thorium resources. Therefore, Advance Heavy Water Reactor is going to acquire significant role in the scenario of Indian nuclear technology, where (Th, Pu)O2 will be utilized as fuel in the outermost ring of the reactor core. This will lead to a complex matrix containing thorium as well as americium, which is formed due to β-decay of plutonium. The amount of americium is dependent on the burn up and the storage time of the Pu based fuels. In the present case, attempt was made to develop a method for the determination of americium as well as thorium by ICP-AES. Two emission lines of americium were identified and calibration curves were established for determination of americium. Though the detection limit of 283.236 nm line (5 ng mL-1) of americium was found to be better than that of 408.930 nm (11 ng mL-1), the former line is significantly interfered by large amount of thorium. Three analytical lines (i.e. 283.242, 283.730 and 401.913 nm) of thorium were identified and calibration curves were established along with their detection limits. It was observed that 283.242 and 401.913 nm line are having similar detection limits (18 and 13 ng mL-1, respectively) which are better than that of 283.730 nm (60 ng mL-1). This can be attributed to the high background of 283.273 nm channel of thorium. The spectral interference study revealed that even small amount of americium has significant contribution on 283.242 nm channel of thorium while the other two channels remain practically unaffected. Considering both these facts, spectral interference and analytical performance (detection limits and sensitivity), it was concluded that 401.913 nm line is the best analytical line out of the three lines for determination of thorium in presence of americium. (author)

  20. Post-test analysis of components from selenide isotope generator modules M-7, M-15, and M-18

    International Nuclear Information System (INIS)

    Several critical components removed from SIG (Selenide Isotope Generator) thermoelectric modules M-7, M-15C, M-15D, and M-18 were examined. These modules failed to show the predicted stability and conversion efficiency. Understanding the degradation and identifying means for preventing it necessitated detailed post-test examinations of key parts in the modules. Steel springs, which provided pressure for contacts at the hot and cold ends of P- or N-legs, relaxed more than expected. Beryllium oxide insulators had dark deposits that caused electrical shorts. The GdSe149 N-leg exhibited cracking. The (Cu,Ag)2Se P-leg lost weight or sublimed excessively in module M-7 and more than expected in the other modules

  1. Post-test analysis of components from selenide isotope generator modules M-7, M-15, and M-18

    Energy Technology Data Exchange (ETDEWEB)

    Wei, G.C.; Keiser, J.R.; Crouse, R.S.; Allen, M.D.; Schaffhauser, A.C.

    1979-05-01

    Several critical components removed from SIG (Selenide Isotope Generator) thermoelectric modules M-7, M-15C, M-15D, and M-18 were examined. These modules failed to show the predicted stability and conversion efficiency. Understanding the degradation and identifying means for preventing it necessitated detailed post-test examinations of key parts in the modules. Steel springs, which provided pressure for contacts at the hot and cold ends of P- or N-legs, relaxed more than expected. Beryllium oxide insulators had dark deposits that caused electrical shorts. The GdSe/sub 1/ /sub 49/ N-leg exhibited cracking. The (Cu,Ag)/sub 2/Se P-leg lost weight or sublimed excessively in module M-7 and more than expected in the other modules.

  2. A novel polysaccharide isolated from mulberry fruits (Murus alba L.) and its selenide derivative: structural characterization and biological activities.

    Science.gov (United States)

    Chen, Chun; Zhang, Bin; Fu, Xiong; Liu, Rui Hai

    2016-06-15

    A novel polysaccharide (MFP3P) was isolated from Murus alba L. through the hot water extraction method followed by chromatographic purification. The chemical structure of MFP3P was elucidated by acid hydrolysis, Smith degradation and methylation analysis, along with FT-IR, GC-MS, (1)H and (13)C NMR spectroscopy. Its morphological properties were further characterized by SEM and AFM. The selenide of the polysaccharide (MFP3P-Se) was obtained by the Na2SeO3/BaCl2 method. The antioxidant properties showed that MFP3P-Se exhibited higher peroxy radical-scavenging capacity than MFP3P in vitro. Moreover, MFP3P-Se had more significant hypoglycemic effects than MFP3P through promoting pancreatic cell proliferation and increasing glucose metabolism and insulin secretion. PMID:27241036

  3. Cuprous Iodide Catalyzed Synthesis of Diaryl Selenide and Telluride from Organoboronic Acids with Diphenyl Diselenide and Ditelluride

    Institute of Scientific and Technical Information of China (English)

    WANG,Lei; WANG,Min; YAN,Jin-Can; LI,Pin-Hua

    2004-01-01

    @@ Organoselenium and tellurium compounds have received much attention not only as synthetic reagents or intermediates in organic synthesis but also as promising donor molecules for conductive materials.[1] A number of synthetic methods have been reported to prepare organoselenium and tellurium derivatives. A convenient and general method to introduce a selenium or tellurium moiety into organic molecules is the reaction of a metal selenolate or tellurolate with appropriate electrophiles such as organic halides, acyl chlorides, epoxides, and α, β-enones.[2] However, it is difficult to synthesize the unsymmetrical diarylselenides and tellurides through the reaction of selenide anion with organic halides because of the less reactivity of aryl halides. To accomplish this purpose, the reaction (iodobenzene with phenylselenol)was generally carried out in the presence of catalysts, ligands and strong bases. But, the reaction needs longer time to accomplish and form the products in moderate yields.

  4. Effect of radiolysis on leachability of plutonium and americium from 76-101 glass. [Glass containing 2 mole % plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Nash, K.L.; Fried, S.; Friedman, A.M.; Susak, N.; Rickert, P.; Sullivan, J.C.; Karim, D.P.; Lam, D.J.

    1982-01-01

    One aspect of the leachability of actinide-bearing glass which has not been adequately addressed is the effect of radiolysis of the system (glass-water) on the amount of actinides liberated from the glass. In the present study, we have investigated the leaching of plutonium and americium from 76-101 glass samples (containing 2 mole % plutonium) in the presence of a one megaRad/hour gamma-radiation field. The presence of the radiation field was found to increase the leaching rate of both plutonium and americium by a factor of five. Speciation studies of the plutonium in the leachate indicate that the plutonium is present predominantly in the higher oxidation states, Pu(V) and Pu(VI) and that it is significantly associated with colloidal particles. Examination of the glass surfaces with x-ray photoemission spectroscopy, XPS, both before and after leaching was carried out; these studies showed lower surface concentrations of plutonium in the samples of glass leached in the radiation field. 1 figure, 3 tables.

  5. Osteosarcoma induction by plutonium-239, americium-241 and neptunium-237 : the problem of deriving risk estimates for man

    International Nuclear Information System (INIS)

    Spontaneous bone cancer (osteosarcoma) represents only about 0.3% of all human cancers, but is well known to be inducible in humans by internal contamination with radium-226 and radium-224. plutonium-239, americium-241 and neptunium-237 form, or will form, the principal long-lived alpha particle emitting components of high activity waste and burnt-up nuclear fuel elements. These three nuclides deposit extensively in human bone and although, fortunately, no case of a human osteosarcoma induced by any of these nuclides is known, evidence from animal studies suggests that all three are more effective than radium-226 in inducing osteosarcoma. The assumption that the ratio of the risk factors, the number of osteosarcoma expected per 10000 person/animal Gy, for radium-226 and any other bone-seeking alpha-emitter will be independent of animal species has formed the basis of all the important studies of the radiotoxicity of actinide nuclides in experimental animals. The aim of this communication is to review the risk factors which may be calculated from the various animal studies carried out over the last thirty years with plutonium-237, americium-241 and neptunium-237 and to consider the problems which may arise in extrapolating these risk factors to homo sapiens

  6. Plutonium and americium in Arctic waters, the North Sea and Scottish and Irish coastal zones (in Fucus, Mytilus and Patella)

    International Nuclear Information System (INIS)

    Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were collected from the Irish coast in 1983. Fallout is found to dominate as a source of 239+240Pu north of latitude 650N, while for 238Pu a substantial fraction originates from European nuclear fuel reprocessing facilities. The 238Pu/239+240Pu isotope ratio provides clear evidence of the transport of effluent plutonium from the latter to Spitsbergen waters. Fallout plutonium in Arctic waters has a residence time of the order of several years, while for Pu from Sellafield we estimate mean residence times of 11-15 months in Scottish waters and, tentatively, 1.5-3 y during transport from the North Channel (north of the Irish Sea) to Spitsbergen. 241Am found in Arctic waters probably originates from the decay of fallout 241Pu and, like Pu, tentatively has a residence time of the order of several years. Americium from Sellafield has an estimated mean residence time of 4-6 months in Scottish waters. (author)

  7. Experimental Study on Behavior of Americium in Pyrochemical Process of Nitride Fuel Cycle

    International Nuclear Information System (INIS)

    R and D on the transmutation of long-lived minor actinides (MA) by the accelerator-driven system (ADS) using nitride fuels is underway at JAEA. In regard to reprocessing technology, pyrochemical process has several advantages in case of treating spent fuel with large decay heat and fast neutron emission, and recovering highly enriched N-15. In the pyrochemical reprocessing, plutonium and MA are dissolved in LiCl-KCl eutectic melts and selectively recovered into liquid cadmium (Cd) cathode by molten salt electrorefining. The electrochemical behavior in LiCl-KCl eutectic melts and the subsequent nitride formation behavior of plutonium and MA recovered in liquid Cd cathode are investigated. In this paper, recent results on electrochemical study of americium (Am) on electrolyses of AmN in LiCl-KCl eutectic melts and nitride formation of Am recovered in the liquid Cd cathode are presented. Electrochemical behavior of Am on anodic dissolution of AmN and recovery of Am into a liquid Cd cathode by electrolyses in LiCl-KCl eutectic melts was investigated by transient electrochemical techniques. The formal standard potential of Am(III)/Am(0) obtained with the liquid Cd electrode is more positive than that calculated for the solid metal electrode. The potential shift is considered to be attributed to the lowering of the activity of Am by the formation of the intermetallic compound with Cd. Potentiostatic electrolyses of AmN in LiCl-KCl eutectic melts containing AmCl3 at 773 K were carried out. Nitrogen gas generated by the anodic dissolution of AmN was observed, and the current efficiency was obtained from the ratio of the amount of released nitrogen gas and the passed electric charge to be 20 - 28 %. Am was recovered as Am-Cd alloy in the liquid Cd cathode, in which AmCd6 type phase was identified besides Cd phase. The recovered Am was converted to AmN by the nitridation-distillation combined method, in which the Am-Cd alloy was heated in nitrogen gas stream at 973 K. These

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

    International Nuclear Information System (INIS)

    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. (author)

  9. Crystal and electronic structures of two new iron selenides: Ba4Fe3Se10 and BaFe2Se4

    International Nuclear Information System (INIS)

    The new ternary selenides, Ba4Fe3Se10 and BaFe2Se4, were synthesized from a reaction of appropriate amounts of elements at high temperature in a silica sealed tube, and their structures were resolved using X-ray single crystal diffraction. BaFe2Se4 crystallizes in the tetragonal space group I4/m with a=8.008(9) Å and c=5.483(3) Å as cell parameters. It is a new compound with a structure isotypical to the sulfide BaFe2S4 which belongs to the infinitely adaptive structures series Ba1+xFe2S4. The second compound, Ba4Fe3Se10, crystallizes in the monoclinic space group P21/n with a=8.8593(1) Å, b=8.8073(1) Å, c=12.2724(1) Å and β=109.037(6)° as cell parameters. It exhibits an original structure with a new type of iron selenide polyhedra. These data were consistent with the powder X-ray diffraction and TEM analyses. Their electronic structures point towards metallicity and electronic correlations for both selenides. - Graphical abstract: Experimental [010] oriented ED pattern and corresponding HREM image of Ba4Fe3Se10. Image calculated with a focus and thickness to 15nm and 8 nm respectively is inserted. Bright contrasts are correlated to Se rows belonging to FeSe3(Se2)2−–FeSe6–FeSe3(Se2)2− trimers. The corresponding structure projection is also shown. - Highlights: • Two new barium iron selenide compounds. • An original structure type Ba4Fe3Se10. • Electronic structure calculations

  10. Synthesis and characterization of (Ni1-xCox)Se2 based ternary selenides as electrocatalyst for triiodide reduction in dye-sensitized solar cells

    Science.gov (United States)

    Theerthagiri, J.; Senthil, R. A.; Buraidah, M. H.; Raghavender, M.; Madhavan, J.; Arof, A. K.

    2016-06-01

    Ternary metal selenides of (Ni1-xCox)Se2 with 0≤x≤1 were synthesized by using one-step hydrothermal reduction route. The synthesized metal selenides were utilized as an efficient, low-cost platinum free counter electrode for dye-sensitized solar cells. The cyclic voltammetry and electrochemical impedance spectroscopy studies revealed that the Ni0.5Co0.5Se2 counter electrode exhibited higher electrocatalytic activity and lower charge transfer resistance at the counter electrode/electrolyte interface than the other compositions for reduction of triiodide to iodide. Ternary selenides of Ni0.5Co0.5Se2 offer a synergistic effect to the electrocatalytic activity for the reduction of triiodide that might be due to an increase in active catalytic sites and small charge transfer resistance. The DSSC with Ni0.5Co0.5Se2 counter electrode achieved a high power conversion efficiency of 6.02%, which is comparable with that of conventional platinum counter electrode (6.11%). This present investigation demonstrates the potential application of Ni0.5Co0.5Se2 as counter electrode in dye-sensitized solar cells.

  11. Investigation of deep level defects in epitaxial semiconducting zinc sulpho-selenide. Progress report, 15 June 1979-14 June 1980

    International Nuclear Information System (INIS)

    In an effort to understand the defect structure of the ternary II-VI compound zinc sulpho-selenide, the binary compound zinc selenide was investigated. Thin single crystalline films of zinc selenide were heteroepitaxially grown on (100) GaAs. Epitaxial layers from 5 to 50 microns thick could be readily grown using a chemical vapor transport technique. The layers had an excellent morphology with few stacking faults and hillocks. Detailed epitaxial growth kinetics were examined as a function of temperature and reactant concentration. It was found that hydrogen flow rate, source and substrate temperature affect the growth rate of the epitaxial films. Au - ZnSe Schottky barrier diodes and ZnSe - GaAs n-p heterojunctions were prepared from the epitaxial layers. Current-voltage characteristics were measured on both types of diodes. From capacitance-voltage measurements the residual doping density of the epitaxial layers were found to be of the order of 1014 - 1015 cm-3. Finally, we have begun to measure the deep level spectrum of both the Schottky barrier diodes and the heterojunctions. Deep level transient spectroscopy appears to be well suited for determining trapping states in ZnSe provided the material has a low enough resistivity

  12. Chemical behaviour of trivalent and pentavalent americium in saline NaCl-solutions. Studies of transferability of laboratory data to natural conditions. Interim report. Reported period: 1.2.1993-31.12.1993; Chemisches Verhalten von drei- und fuenfwertigem Americium in Salinen NaCl-Loesungen. Untersuchung der Uebertragbarkeit von Labordaten auf natuerliche Verhaeltnisse. Zwischenbericht. Berichtszeitraum 1.2.1993-31.12.1993

    Energy Technology Data Exchange (ETDEWEB)

    Runde, W.; Kim, J.I.

    1994-09-15

    In order to clarify the chemical behaviour of Americium in saline aqueous systems relevant for final storage this study deals with the chemical reactions of trivalent and pentavalent Americium in NaCl-solutions under the influence of radiolysis from its own alpha radiation. The focus of the study was on investigating the geologically relevant reactions, such as hydrolysis or carbonate- and chloride complexing in solid-liquid equilibriums. Comprehensive measurements on solubility and spectroscopic studies in NaCl-solutions were carried out in a CO{sub 2}-free atmosphere and 10{sup -2} atm CO{sub 2} partial pressure. Identification and characterisation of the AM (III) and AM(V) solid phases were supplemented by structural research with the chemically analogue EU (III) and Np(V) compounds. The alpha-radiation induced radiolysis in saline NaCl solutions and the redox behaviour of Americium which was influenced thereby were spectroscopically quantified. (orig.) [Deutsch] Zur Klaerung des chemischen Verhaltens von Americium in endlagerrelevanten salinen aquatischen Systemen befasst sich die vorliegende Arbeit mit den chemischen Reaktionen des drei- und fuenfwertigen Americiums in NaCl-Loesungen unter dem Einfluss der Radiolyse durch die eigene {alpha}-Strahlung. Der Schwerpunkt dieser Arbeit lag auf der Untersuchung der geologisch relevanten Reaktionen, wie Hydrolyse sowie Carbonat- und Chloridkomplexierung in fest-fluessig Gleichgewichtssystemen. Hierzu wurden umfassende Loeslichkeitsmessungen und spektroskopische Untersuchungen in NaCl-Loesungen, sowohl unter CO{sub 2}-freier Atmosphaere als auch unter 10{sup -2} atm CO{sub 2}-Partialdruck, durchgefuehrt. Die Identifizierung und Charakterisierung der Am(III)- und Am(V)-Festphasen wurde ergaenzt durch strukturelle Untersuchungen mit den chemisch analogen Eu(III)- und Np(V)-Verbindungen. Die von der {alpha}-Strahlung induzierte Radiolyse in salinen NaCl-Loesungen und das dadurch beeinflusste Redoxverhalten von Americium

  13. Influence of an alkoxy group on bis-triazinyl-pyridines for selective extraction of americium(III)

    International Nuclear Information System (INIS)

    The extraction of americium(III), curium(III), and lanthanides(III) from nitric acid by 2,6-bis-(5,6-dimethyl-[1,2,4]-triazin-3-yl)-pyridine and 2,6-bis-(5,6-dimethyl-[1,2,4]-triazin- 3-yl)-4-methoxy-pyridine was studied. The physico-chemical properties of these ligands, such as the protonation and complexation constants, were also determined to describe the influence of different substituent groups. The selectivity of substituted-BTP was confirmed both in complexation and in solvent extraction experiments. The presence of an alkoxy-group in position 4 of the pyridine decreases the BTP selectivity. Influence of a long alkyl chain on protonation and complexation constants was also studied with 2,6-bis-(5,6-dimethyl-[1,2,4]- triazin-3-yl)-4-dodecyloxy-pyridine. (authors)

  14. Solvent extraction of europium and americium into phenyltrifluoromethyl sulfone by using synergistic mixture of hydrogen dicarbollylcobaltate and 'classical' CMPO

    International Nuclear Information System (INIS)

    Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of octyl-phenyl-N,N-diisobutylcarbamoylmethyl phosphine oxide ('classical' CMPO, L) has been investigated. The equilibrium data have been explained assuming that the complexes HL+, HL2+, ML23+, ML33+ and ML43+ (M3+ Eu3+, Am3+) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in FS 13 saturated with water have been determined. It was found that the stability constants of the corresponding complexes EuLn3+ and AmLn3+, where n 2, 3, 4 and L is 'classical' CMPO, in water-saturated FS 13 are comparable. (author)

  15. Recovery, purification and concentration of plutonium and americium from the aqueous wastes discharged in the reprocessing process studies

    International Nuclear Information System (INIS)

    For recovering and purifying plutonium and americium from the aqueous wastes occurring in the process studies on reprocessing, a standard procedure has been established for use in the laboratory works, through the preliminary tests of the precipitation as hydroxides and the anion exchange in nitrate media. The procedure was proven in the treatment of actual wastes, of which the results were contributed to determine the process conditions in the plutonium purification and product concentration of the JAERI Reprocessing Test Plant. The preliminary tests also include washing of U and Am recovery from the anion-exchanger in nitrate media, direct ion-exchange recovery of Pu from the TBP phase and elution of Am from the cation-exchanger. (auth.)

  16. Plutonium and americium in fish, shellfish and seaweed in the Irish environment and their contribution to dose

    International Nuclear Information System (INIS)

    Plutonium and americium activity concentrations in fish and shellfish landed in Ireland in the period 1988 to 1997 are presented. Activity concentrations in fish are low and often below detection limits, while those in mussels and oysters sampled on the northeast coast show no significant signs of decline. The estimated doses to hypothetical typical and heavy seafood consumers remain below 1 μSv yr-1 (committed effective dose).Plutonium activity concentrations measured in Fucus vesiculosus around the Irish coastline have not fallen appreciably in the ten year period between 1986 and 1996. Furthermore, the mean 238Pu/239,240Pu ratio of 0.17±0.05 in Fucus vesiculosus from the west coast of Ireland demonstrates the increasing significance of Sellafield-derived plutonium in those waters. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  17. The bone volume effect on the dosimetry of plutonium-239 and americium-241 in the skeleton of man and baboon

    International Nuclear Information System (INIS)

    Studies were undertaken using bone removed from young adult baboons, which had been contaminated with plutonium-239 at various times prior to sacrifice, and human bone from adult male (USTR Case 246), who had received an internal deposition of americium-241 as a result of a glove-box explosion 11 years prior to his death. The baboon bone was supplied by the CEA, France, and the human bone by the United States Transuranium registry. The bone samples, examined by qualitative and quantitative autoradiography with CR 39 detectors, demonstrated the rapid redistribution of bone surface-seeking radionuclides in younger primates due to growth and the slower, bone turnover driven redistribution in the adult human bone. In both species, primary and secondary surface deposits of radionuclide remained conspicious despite bone activity; true volumization of radionuclide was seldom seen. The dosimetric implications of these findings are discussed. (author) 21 refs.; 6 figs.; 4 tabs

  18. Iron selenide films by aerosol assisted chemical vapor deposition from single source organometallic precursor in the presence of surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Raja Azadar [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Badshah, Amin, E-mail: aminbadshah@yahoo.com [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Younis, Adnan [School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia); Khan, Malik Dilshad [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Akhtar, Javeed [Department of Physics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, Islamabad (Pakistan)

    2014-09-30

    This article presents the synthesis and characterization (multinuclear nuclear magnetic resonance, Fourier transform infrared spectroscopy, carbon–hydrogen–nitrogen–sulfur analyzer, atomic absorption spectrometry and thermogravimetric analysis) of a single source organometallic precursor namely 1-acetyl-3-(4-ferrocenylphenyl)selenourea for the fabrication of iron selenide (FeSe) films on glass substrates using aerosol assisted chemical vapor deposition (AACVD). The changes in the morphologies of the films have been monitored by the use of two different surfactants i.e. triton X-100 and tetraoctylphosphonium bromide during AACVD. The role of surfactant has been evaluated by examining the interaction of the surfactants with the precursor by using UV–vis spectroscopy and cyclic voltammetry. The fabricated FeSe films have been characterized with powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. - Highlights: • Ferrocene incorporated selenourea (FIS) has been synthesized and characterized. • FeSe thin films have been fabricated from FIS. • Mechanism of film growth was studied with cyclic voltammetry and UV–vis spectroscopy.

  19. Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

    International Nuclear Information System (INIS)

    This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 2250C without any signs of thermal performance degradation

  20. Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors

    Science.gov (United States)

    Wang, Qisi; Park, J. T.; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J. W.; Ivanov, A.; Chi, Songxue; Matsuda, M.; Cao, Huibo; Birgeneau, R. J.; Efremov, D. V.; Zhao, Jun

    2016-05-01

    An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s -wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s± or d -wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in Tc in the S-doped iron selenide superconductors KxFe2 -y(Se1-zSz) 2 . We show that a rather sharp magnetic resonant mode well below the superconducting gap (2 Δ ) in the undoped sample (z =0 ) is replaced by a broad hump structure above 2 Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

  1. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

    Science.gov (United States)

    Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

    2016-02-01

    Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. PMID:26615488

  2. Structural and Optical Studies of 100 MeV Ni+7 Irradiated Cadmium Selenide Thin Films

    Directory of Open Access Journals (Sweden)

    Rajesh Singh

    2015-10-01

    Full Text Available The effect of irradiation with Swift (100 MeV Ni+ 7 ions on the structural and optical properties of Cadmium Selenide (CdSe thin films have been investigated at different fluencies in the range of 1  1011-1  1013 ions/cm – 2. The CdSe films on glass substrates were prepared by thermal evaporation. The structural and optical changes with respect to increasing fluence were observed by the means of X-ray diffraction (XRD, UV-VIS and Raman spectroscopy. After irradiating the films with Ni+ 7 ions XRD show the increased in peak intensity and crystallite size with increasing fluence. The UV-VIS-IR spectroscopy revealed that there is decrease in band gap energy of the films after irradiation with increasing fluencies. Raman spectrum for as deposited and irradiated films show two peak, one at 209 cm – 1 and at 410 cm – 1 which is assigned to the longitudinal optical (LO phonon mode.

  3. Influence of growth and photocatalytic properties of copper selenide (CuSe) nanoparticles using reflux condensation method

    International Nuclear Information System (INIS)

    Influence of reaction conditions on the synthesis of copper selenide (CuSe) nanoparticles and their photo degradation activity is studied. Nearly monodispersed uniform size (23–44 nm) nanoparticles are synthesized by varying the reaction conditions using reflux condensation method. The obtained nanoparticles are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and UV–visible absorption spectroscopy. The X-ray diffraction analysis of the sample shows the formation of nanoparticles with hexagonal CuSe structure. The result indicates that on increasing the reaction time from 4 to 12 h, the particle size decreases from 44 to 23 nm, but an increase in the reaction temperature increases the particle size. The calculated band gap Eg is ranging from 2.34 to 3.05 eV which is blue shifted from the bulk CuSe (2.2 eV). The photocatalytic degradation efficiency of the CuSe nanoparticles on two organic dyes Methylene blue (MB) and Rhodamine-B (RhB) in aqueous solution under UV region is calculated as 76 and 87% respectively.

  4. Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

    Energy Technology Data Exchange (ETDEWEB)

    Strazza, N.P.

    1979-06-30

    This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 225/sup 0/C without any signs of thermal performance degradation. (TFD)

  5. Highly Efficient Copper-Indium-Selenide Quantum Dot Solar Cells: Suppression of Carrier Recombination by Controlled ZnS Overlayers.

    Science.gov (United States)

    Kim, Jae-Yup; Yang, Jiwoong; Yu, Jung Ho; Baek, Woonhyuk; Lee, Chul-Ho; Son, Hae Jung; Hyeon, Taeghwan; Ko, Min Jae

    2015-11-24

    Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date. PMID:26431392

  6. Production of no-carrier-added radiobromine. new nickel selenide target and optimized separation by dry distillation

    Energy Technology Data Exchange (ETDEWEB)

    Breunig, Katharina; Spahn, Ingo; Spellerberg, Stefan; Coenen, Heinz H. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM), Nuklearchemie (INM-5)

    2015-07-01

    Nickel(II) selenide (NiSe) was investigated as a new high-current target material for cyclotron production of radiobromine, as it contains a higher amount of selenium and has a lower melting point than the widely used Cu{sub 2}Se. Using a slanted target system, NiSe was successfully tested up to beam currents of 16 μA so far. With regard to the isolation of no-carrier-added (n.c.a.) radiobromide from the target material, an improved dry distillation device with high yields of 76%-86% was developed. The implementation of a special custom-made quartz funnel decreased the dead volume of the apparatus and a quartz capillary for trapping the radiobromine allowed to concentrate the radioactivity in a small volume of less than 100 μL of 0.1 M NaOH, ready for immediate subsequent radiosyntheses. Thus, the new apparatus improves the handling of the isolation procedure and the radioactive product. The radiochemical purity of the resulting solution of n.c.a. [*Br]bromide was verified by radio-IC where no other species were detected.

  7. Temperature anomaly of the coefficient of ultrasonic absorption by electrons of hybridized states of cobalt impurities in mercury selenide

    Science.gov (United States)

    Zhevstovskikh, I. V.; Okulov, V. I.; Gudkov, V. V.; Mayakin, V. Yu.; Sarychev, M. N.; Andriichuk, M. D.; Paranchich, L. D.

    2015-05-01

    The effects of the interaction of ultrasound with donor d electrons of cobalt impurity atoms at low concentrations in mercury selenide crystals have been investigated. The temperature dependences of the electronic contribution to the absorption coefficient at a frequency of 53 MHz in crystals with cobalt concentrations from 1018 to 1020 cm-3 and in the undoped crystal have been observed experimentally. It has been found that crystals with impurities are characterized by an anomalous nonmonotonic temperature dependence of the absorption coefficient of the slow transverse wave in a narrow temperature range near 10 K. A smooth monotonic temperature dependence has been observed for longitudinal and fast transverse waves. Based on the developed theoretical interpretation, it has been established that the anomaly in the temperature dependence of the absorption coefficient of a slow transverse wave is associated with the hybridization of impurity d states in the conduction band of the crystal. A comparison of the theoretical and experimental dependences has made it possible to determine the parameters characterizing the hybridized electronic states.

  8. Iron selenide films by aerosol assisted chemical vapor deposition from single source organometallic precursor in the presence of surfactants

    International Nuclear Information System (INIS)

    This article presents the synthesis and characterization (multinuclear nuclear magnetic resonance, Fourier transform infrared spectroscopy, carbon–hydrogen–nitrogen–sulfur analyzer, atomic absorption spectrometry and thermogravimetric analysis) of a single source organometallic precursor namely 1-acetyl-3-(4-ferrocenylphenyl)selenourea for the fabrication of iron selenide (FeSe) films on glass substrates using aerosol assisted chemical vapor deposition (AACVD). The changes in the morphologies of the films have been monitored by the use of two different surfactants i.e. triton X-100 and tetraoctylphosphonium bromide during AACVD. The role of surfactant has been evaluated by examining the interaction of the surfactants with the precursor by using UV–vis spectroscopy and cyclic voltammetry. The fabricated FeSe films have been characterized with powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. - Highlights: • Ferrocene incorporated selenourea (FIS) has been synthesized and characterized. • FeSe thin films have been fabricated from FIS. • Mechanism of film growth was studied with cyclic voltammetry and UV–vis spectroscopy

  9. Loading of atorvastatin and linezolid in β-cyclodextrin-conjugated cadmium selenide/silica nanoparticles: A spectroscopic study.

    Science.gov (United States)

    Antony, Eva Janet; Shibu, Abhishek; Ramasamy, Sivaraj; Paulraj, Mosae Selvakumar; Enoch, Israel V M V

    2016-08-01

    The preparation of β-cyclodextrin-conjugated cadmium selenide-silica nanoparticles, the loading of two drugs viz., Atorvastatin and linezolid in the cyclodextrin cavity, and the fluorescence energy transfer between CdSe/SiO2 nanoparticles and the drugs encapsulated in the cyclodextrin cavity are reported in this paper. IR spectroscopy, X-ray diffractometry, transmission electron microscopy, and particle size analysis by light-scattering experiment were used as the tools of characterizing the size and the crystal system of the nanoparticles. The nanoparticles fall under hexagonal system. The silica-shell containing CdSe nanoparticles were functionalized by reaction with aminoethylamino-β-cyclodextrin. Fluorescence spectra of the nanoparticles in their free and drug-encapsulated forms were studied. The FÖrster distances between the encapsulated drugs and the CdSe nanoparticles are below 3nm. The change in the FÖrster resonance energy parameters under physiological conditions may aid in tracking the release of drugs from the cavity of the cyclodextrin. PMID:27157743

  10. Syntheses and characterization of two new selenides Ba5Al2Se8 and Ba5Ga2Se8

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Research highlights: → Two new compounds Ba5M2Se8 (M = Al, Ga) have been synthesized for the first time. → The crystal structures contain isolated MSe4 tetrahedra separated by Ba atoms. → The measured optical band gap is 2.51(2) eV for Ba5Ga2Se8. → The Ba 5d orbitals were found to have significant contribution to the energy bands around Fermi level. - Abstract: Two new barium selenides Ba5Al2Se8 and Ba5Ga2Se8 have been synthesized by solid-state reactions. The structures of Ba5Ga2Se8 and Ba5Al2Se8 were determined by single-crystal X-ray diffraction method and the Rietveld method, respectively. The two isostructural compounds crystallize in space group Cmca of the orthorhombic system with isolated MSe4 (M = Al, Ga) tetrahedra separated by Ba atoms. The optical band gap of 2.51(2) eV for Ba5Ga2Se8 was deduced from the diffuse reflectance spectrum. Band structure calculation indicates that Ba5Ga2Se8 is a direct-gap semiconductor. The valence band maximum is dominated by Se 4p orbitals, while the Ba 5d orbitals have the largest contribution to bottom of the conduction band.

  11. Production of no-carrier-added radiobromine. new nickel selenide target and optimized separation by dry distillation

    International Nuclear Information System (INIS)

    Nickel(II) selenide (NiSe) was investigated as a new high-current target material for cyclotron production of radiobromine, as it contains a higher amount of selenium and has a lower melting point than the widely used Cu2Se. Using a slanted target system, NiSe was successfully tested up to beam currents of 16 μA so far. With regard to the isolation of no-carrier-added (n.c.a.) radiobromide from the target material, an improved dry distillation device with high yields of 76%-86% was developed. The implementation of a special custom-made quartz funnel decreased the dead volume of the apparatus and a quartz capillary for trapping the radiobromine allowed to concentrate the radioactivity in a small volume of less than 100 μL of 0.1 M NaOH, ready for immediate subsequent radiosyntheses. Thus, the new apparatus improves the handling of the isolation procedure and the radioactive product. The radiochemical purity of the resulting solution of n.c.a. [*Br]bromide was verified by radio-IC where no other species were detected.

  12. An approach to global rovibrational analysis based on anharmonic ladder operators: Application to Hydrogen Selenide (H280Se)

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic diagram of a bent triatomic molecule, depicting the atom numbering, and molecular axis system. An algebraic approach to perform global rovibrational analysis is presented. Highlights: ► Novel approach for a global rovibrational analysis of polyatomic molecules spectra. ► One-dimensional vibron model limit combined with rotational degrees of freedom. ► Phase space Hamiltonian written in terms of anharmonic ladder operators. ► Algebraic calculations performed with a symmetry-adapted rovibrational basis. ► Description of the rovibrational spectrum of H2Se in the ground electronic state. - Abstract: An algebraic approach to perform global rovibrational analysis of molecular spectra is presented. The approach combines the one-dimensional limit of the vibron model with rotational degrees of freedom. The model is based on the expression of the phase space Hamiltonian in terms of anharmonic ladder operators and the use of a symmetry-adapted basis set given by the linear combination of products of local vibrational and rotational wavefunctions. As an example we model the rovibrational spectra of a bent triatomic molecule, providing a global analysis for vibrational bands up to polyad 12 and Jmax = 5 of Hydrogen Selenide (H2Se). Satisfactory fits of vibrational and rovibrational energies are obtained. A prediction of 2579 rovibrational energies up to J ⩽ 5 and polyad 12 for the 140 lowest vibrational bands is also obtained. A possible extension of the model to reach spectroscopic quality results in larger molecular systems is also given.

  13. Digital radiology using active matrix readout of amorphous selenium: radiation hardness of cadmium selenide thin film transistors.

    Science.gov (United States)

    Zhao, W; Waechter, D; Rowlands, J A

    1998-04-01

    A flat-panel x-ray imaging detector using active matrix readout of amorphous selenium (a-Se) is being investigated for digital radiography and fluoroscopy. The active matrix consists of a two-dimensional array of thin film transistors (TFTs). Radiation penetrating through the a-Se layer will interact with the TFTs and it is important to ensure that radiation induced changes will not affect the operation of the x-ray imaging detector. The methodology of the present work is to investigate the effects of radiation on the characteristic curves of the TFTs using individual TFT samples made with cadmium selenide (CdSe) semiconductor. Four characteristic parameters, i.e., threshold voltage, subthreshold swing, field effect mobility, and leakage current, were examined. This choice of parameters was based on the well established radiation damage mechanisms for crystalline silicon metal-oxide-semiconductor field-effect transistors (MOSFETs), which have a similar principle of operation as CdSe TFTs. It was found that radiation had no measurable effect on the leakage current and the field effect mobility. However, radiation shifted the threshold voltage and increased the subthreshold swing. But even the estimated lifetime dose (50 Gy) of a diagnostic radiation detector will not affect the normal operation of an active matrix x-ray detector made with CdSe TFTs. The mechanisms of the effects of radiation will be discussed and compared with those for MOSFETs and hydrogenated amorphous silicon (a-Si:H) TFTs. PMID:9571621

  14. Pulsed voltage deposited lead selenide thin film as efficient counter electrode for quantum-dot-sensitized solar cells

    Science.gov (United States)

    Jin, Bin Bin; Wang, Ye Feng; Wang, Xue Qing; Zeng, Jing Hui

    2016-04-01

    Lead selenide (PbSe) thin films were deposited on fluorine doped tin oxide (FTO) glass by a facile one-step pulse voltage electrodeposition method, and used as counter electrode (CE) in CdS/CdSe quantum dot-sensitized solar cells (QDSSCs). A power conversion efficiency of 4.67% is received for the CdS/CdSe co-sensitized solar cells, which is much better than that of 2.39% received using Pt CEs. The enhanced performance is attributed to the extended absorption in the near infrared region, superior electrocatalytic activity and p-type conductivity with a reflection of the incident light at the back electrode in addition. The physical and chemical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), reflectance spectra, electrochemical impedance spectroscopy (EIS) and Tafel polarization measurements. The present work provides a facile pathway to an efficient CE in the QDSSCs.

  15. Thin-film copper indium gallium selenide solar cell based on low-temperature all-printing process.

    Science.gov (United States)

    Singh, Manjeet; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-09-24

    In the solar cell field, development of simple, low-cost, and low-temperature fabrication processes has become an important trend for energy-saving and environmental issues. Copper indium gallium selenide (CIGS) solar cells have attracted much attention due to the high absorption coefficient, tunable band gap energy, and high efficiency. However, vacuum and high-temperature processing in fabrication of solar cells have limited the applications. There is a strong need to develop simple and scalable methods. In this work, a CIGS solar cell based on all printing steps and low-temperature annealing is developed. CIGS absorber thin film is deposited by using dodecylamine-stabilized CIGS nanoparticle ink followed by printing buffer layer. Silver nanowire (AgNW) ink and sol-gel-derived ZnO precursor solution are used to prepare a highly conductive window layer ZnO/[AgNW/ZnO] electrode with a printing method that achieves 16 Ω/sq sheet resistance and 94% transparency. A CIGS solar cell based on all printing processes exhibits efficiency of 1.6% with open circuit voltage of 0.48 V, short circuit current density of 9.7 mA/cm(2), and fill factor of 0.34 for 200 nm thick CIGS film, fabricated under ambient conditions and annealed at 250 °C. PMID:25180569

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

    Science.gov (United States)

    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.

  17. Stability of penta- and hexavalent americium in the solutions of sodium peroxydisulfate and sodium bromate at intensive internal α-irradiation

    International Nuclear Information System (INIS)

    The spectrometric method has been used for studying the dependence of the rates of radiolytic reduction of Am(5) and (6) on the initial concentration of sodium persulfate and bromate, Am(5) and (6), acidity, and the dose rate of inner alpha-irradiation of the solutions. The high dose rates of inner alpha-irradiation of solutions (up to 3.25x1021 eV/lxmin-250Ci/l) have been attained with the aid of curium isotopes. The stability of americium (6) ions towards the action of ionizing radiation in solutions of sodium persulfate and bromate has been shown to be considerable lower than that of americium (5). The chemical difference has been shown in radiolytic behaviour between Am(5) and Am(6) ions in solutions of sodium persulfate and bromate. The equations have been derived showing the dependence of the rates of Am(6) and Am(5) reduction of different variables

  18. A Density Functional Study of Atomic Hydrogen and Oxygen Chemisorption on the Relaxed (0001) Surface of Double Hexagonal Close Packed Americium

    OpenAIRE

    Dholabhai, P. P.; Atta-Fynn, R.; A.K. Ray

    2009-01-01

    Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption energies were optimized with respect to the distance of the adatom from the relaxed surface for three adsorption sites, namely top, bridge, and hollow hcp sites, the adlayer str...

  19. Distribution, retention and dosimetry of plutonium and americium in the rat, dog and monkey after inhalation of an industrial-mixed uranium and plutonium oxide aerosol

    International Nuclear Information System (INIS)

    This study provides information on patterns of radiation dose in laboratory animals after inhalation exposure to an aerosol of one form of mixed uranium and plutonium oxide. The aerosol contained a mixture of UO2 and 750 deg C heat-treated PuO2 obtained from the ball milling operation in a mixed-oxide fuel fabrication process. Americium-241 from the decay of 241Pu was also present in the PuO2 matrix. Fischer-344 rats, Beagle dogs, and Cynomolgus and Rhesus monkeys inhaled aerosols re-generated from dry mixed oxide powders with particle size distribution characteristics similar to those observed in samples collected at the industrial site. Clearance from the lung and distribution in other tissues of the plutonium from this UO2 + PuO2 admixture was similar to what has been observed for PuO2 from laboratory-produced aerosols. The UO2-PuO2 aerosol was relatively insoluble in the lungs of all species. Monkeys and rats cleared plutonium and americium from their lungs faster than dogs. Very little plutonium or americium translocated within the first 2 yr after exposure to tissues other than tracheobronchial lymph nodes. The greater accumulation of plutonium and americium in the tracheobronchial lymph nodes of dogs as compared to monkeys and rats combined with the more rapid initial clearance of these radionuclides from the lungs of rats and monkeys suggests that errors could result from using data from a single animal species to estimate risk to humans from inhalation of these industrial aerosols. (author)

  20. Experimental study of Americium-241 biokinetics in Homarus Gammarus lobster. Analysis of the accumulation and detoxication mechanisms at the sub-cellular level

    International Nuclear Information System (INIS)

    The Americium 241 radioelement accumulation and elimination rate and mechanisms in the lobster organism have been experimentally studied; incorporation and detoxification capacities of each organ are evaluated. The existence of various biological compartments is shown; the major role of the digestive gland in accumulation of the radioelement, its distribution towards the various organs, and its resorption is comprehensively described, with an analysis at the subcellular and molecular levels. 401 p., 65 fig., 43 tab., 428 ref

  1. Obtenção de filmes espessos de seleneto de cobre sobre carbono vítreo, ouro, titânio e cobre Obtaining copper selenide thick films on vitreous carbon, gold, titanium and copper

    Directory of Open Access Journals (Sweden)

    Adriano César Rabelo

    2007-04-01

    Full Text Available Copper selenide (berzelianite films were prepared on the title substrates using the chemical bath deposition technique (CBD. Film composition was determined by energy dispersion of x-rays. The kinetics of film growth is parabolic and film adherence limits the film thickness. On titanium, copper selenide forms islands that do not completely cover the surface, unless the substrate is prepared with a tin oxide layer; film composition also depends on the titanium oxide layer. On vitreous carbon, CBD and mechanical immobilization techniques lead to films with similar resistances for the electron transfer across the film/substrate interface. On gold, composition studies revealed that film composition is always the same if the pH is in the range from 8 to 12, in contrast to films prepared by an ion-ion combination route. On copper, a new procedure for obtaining copper selenide films as thick as 5 µm has been developed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Prieur, D., E-mail: dam.prieur@gmail.com [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Lebreton, F. [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze cedex (France); Martin, P.M. [CEA, DEN, DEC/SESC/LLCC, 13108 Saint-Paul-Lez-Durance cedex (France); Caisso, M. [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze cedex (France); Butzbach, R. [Helmholtz Zentrum Dresden Rossendorf (HZDR), Institute of Radiochemistry, P.O. Box 10119, 01314 Dresden (Germany); Somers, J. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Delahaye, T. [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze cedex (France)

    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.

  3. An experimental study of americium-241 biokinetics in the Lobster Homarus Gammarus. Analysis of the accumulation/storage and detoxification processes at the subcellular level

    International Nuclear Information System (INIS)

    An experimental study of americium-241 kinetics has been conducted in the lobster Homarus gammmarus. The investigations were conducted at all the levels from the whole body to the subcellular and molecular levels. The animals were contaminated by a single or chronic ingestion of 241 Am labelled mussels. Assessments of accumulation, elimination and distribution of the radionuclide were established on organisms kept in the laboratory; they made it possible to demonstrate the importance of the digestive gland in the radionuclide transfer pathways. The preliminary results led to structural then ultrastructural investigations of the digestive gland in association with radioautographic studies and cellular extractions methods. Four cellular types were demonstrated, only two of them being implied in the radionuclide retention, the former being responsible for americium intake and the latter for its long-term retention. By means of biochemical techniques, subcellular accumulation was studied and the organelles implied in the nuclide retention were specified. Finally, a method of cellular nuclei dissociation was developed; it made it possible to analyse the molecular nature of americium ligands and to demonstrate the function of the protein nuclear matrix in the nuclide retention

  4. A new method for the determination of plutonium and americium using high pressure microwave digestion and alpha-spectrometry or ICP-SMS

    International Nuclear Information System (INIS)

    Plutonium and americium are radionuclides particularly difficult to measure in environmental samples because they are a-emitters and therefore necessitate a careful separation before any measurement, either using radiometric methods or ICP-SMS. Recent developments in extraction chromatography resins such as EichromR TRU and TEVA have resolved many of the analytical problems but drawbacks such as low recovery and spectral interferences still occasionally occur. Here, we report on the use of the new EichromR DGA resin in association with TEVA resin and high pressure microwave acid leaching for the sequential determination of plutonium and americium in environmental samples. The method results in average recoveries of 83 ± 15% for plutonium and 73 ± 22% for americium (n = 60), and a less than 10% deviation from reference values of four IAEA reference materials and three samples from intercomparisons exercises. The method is also suitable for measuring 239Pu in water samples at the μBq/l level, if ICP-SMS is used for the measurement. (author)

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

    International Nuclear Information System (INIS)

    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. - Graphical abstract: Formation of (UIV/V,AmIII)O2 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. • UV and AmIII are formed in equimolar proportions

  6. Preliminary results from uranium/americium affinity studies under experimental conditions for cesium removal from NPP ''Kozloduy'' simulated wastes solutions

    International Nuclear Information System (INIS)

    We use the approach described by Westinghouse Savannah River Company using ammonium molybdophosphate (AMP) to remove elevated concentrations of radioactive cesium to facilitate handling waste samples from NPP Kozloduy. Preliminary series of tests were carried out to determine the exact conditions for sufficient cesium removal from five simulated waste solutions with concentrations of compounds, whose complexing power complicates any subsequent processing. Simulated wastes solutions contain high concentrations of nitrates, borates, H2C2O4, ethylenediaminetetraacetate (EDTA) and Citric acid, according to the composition of the real waste from the NPP. On this basis a laboratory treatment protocol was created. This experiment is a preparation for the analysis of real waste samples. In this sense the results are preliminary. Unwanted removal of non-cesium radioactive species from simulated waste solutions was studied with gamma spectrometry with the aim to find a compromise between on the one hand the AMP effectiveness and on the other hand unwanted affinity to AMP of Uranium and Americium. Success for the treatment protocol is defined by proving minimal uptake of U and Am, while at the same time demonstrating good removal effectiveness through the use of AMP. Uptake of U and Am were determined as influenced by oxidizing agents at nitric acid concentrations, proposed by Savannah River National laboratory. It was found that AMP does not significantly remove U and Am when concentration of oxidizing agents is more than 0.1M for simulated waste solutions and for contact times inherent in laboratory treatment protocol. Uranium and Americium affinity under experimental conditions for cesium removal were evaluated from gamma spectrometric data. Results are given for the model experiment and an approach for the real waste analysis is chosen. Under our experimental conditions simulated wastes solutions showed minimal affinity to AMP when U and Am are most probably in the

  7. Exploring the electronic structure and optical properties of the quaternary selenide compound, Ba4Ga4SnSe12: For photovoltaic applications

    International Nuclear Information System (INIS)

    Due to huge demand on discovering new materials for energy, we used first-principle calculations to explore the electronic structure and optical properties of a recent quaternary selenide, namely Ba4Ga4SnSe12. The electronic structure and the optical properties of Ba4Ga4SnSe12 were calculated through a reliable approach of Engle Vosko-GGA (EV-GGA). We found that Ba4Ga4SnSe12 has a direct band gap of 2.14 eV positioned at Γ. Acquiring the fundamental characteristics of Ba4Ga4SnSe12, we studied the linear optical properties like dielectric function in the energy range of 0–14 eV. From the dielectric function we noticed a weak directional anisotropy for the two components. The absorption spectrum indicates the possibility of greater multiple direct and indirect inter-band transitions in the visible regions and shows similar behavior with experimental spectrum. Ba4Ga4SnSe12 can be used as shielding material from UV radiations. Present study predicts that the Ba4Ga4SnSe12 is promising for photovoltaic applications due to their high absorption of solar radiations and photoconductivity in the visible range. - Graphical abstract: Interesting quaternary selenide compound, Ba4Ga4SnSe12, for photovoltaic applications. - Highlights: • Ba4Ga4SnSe12 is a quaternary selenide designed for PV and thermoelectric. • Ba4Ga4SnSe12 has a direct band gap of 2.14 eV. • Ba4Ga4SnSe12, has a maximum reflectivity in the visible and UV regions

  8. Thin film metallic glass as a diffusion barrier for copper indium gallium selenide solar cell on stainless steel substrate: A feasibility study

    Science.gov (United States)

    Diyatmika, Wahyu; Xue, Lingjun; Lin, Tai-Nan; Chang, Chia-wen; Chu, Jinn P.

    2016-08-01

    The feasibility of using Zr53.5Cu29.1Al6.5Ni10.9 thin-film metallic glass (TFMG) as a diffusion barrier for copper indium gallium selenide (CIGS) solar cells on stainless steel (SS) is investigated. The detrimental Fe diffusion from SS into CIGS is found to be effectively hindered by the introduction of a 70-nm-thick TFMG barrier; the cell performance is thus improved. Compared with the 2.73% of CIGS on bare SS, a higher efficiency of 5.25% is obtained for the cell with the Zr52Cu32Al9Ni7 TFMG barrier.

  9. Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

    Science.gov (United States)

    Sandoval-Paz, M. G.; Rodríguez, C. A.; Porcile-Saavedra, P. F.; Trejo-Cruz, C.

    2016-07-01

    Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films.

  10. The stability domain of the selenide kesterite photovoltaic materials and NMR investigation of the Cu/Zn disorder in Cu2ZnSnSe4 (CZTSe).

    Science.gov (United States)

    Choubrac, Léo; Lafond, Alain; Paris, Michaël; Guillot-Deudon, Catherine; Jobic, Stéphane

    2015-06-21

    Bulk compounds, prepared via the ceramic route, related to Cu2ZnSnSe4 (CZTSe), a material considered for use in photovoltaic devices, were investigated using NMR spectroscopy, electron-probe microanalyses and X-ray diffraction. These materials adopt the kesterite structure regardless of the Cu and Zn contents. It is also shown that the stability domain of the copper-poor quaternary phases is wider for selenide derivatives than for sulphides. Finally, the Cu/Zn disorder level in CZTSe is found to be higher when the samples are quenched, which is reminiscent of the behaviour of the parent sulphide compounds CZTS. PMID:25990030

  11. Polyamide–thallium selenide composite materials via temperature and pH controlled adsorption–diffusion method

    Energy Technology Data Exchange (ETDEWEB)

    Ivanauskas, Remigijus; Samardokas, Linas [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu str. 19, Kaunas LT-50254 (Lithuania); Mikolajunas, Marius; Virzonis, Darius [Department of Technology, Kaunas University of Technology, Panevezys Faculty, Daukanto 12, 35212 Panevezys (Lithuania); Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

    2014-10-30

    Graphical abstract: Single phase polyamide–thallium selenide hybrid functional materials were synthesized for solar energy conversion. - Highlights: • Thallium selenide–polyamide composite materials surfaces synthesized. • Mixed phase composition confirmed by XRD. • Increased temperature resulted in a denser surface packing. • Urbach energies correlated with AFM showing decreased structural disorder. • Annealing in N{sub 2} at 100 °C yielded a single TlSe phase. - Abstract: Composite materials based on III–VI elements are promising in designing efficient photoelectronic devices, such as thin film organic–inorganic solar cells. In this work, TlSe composite materials were synthesized on a model polymer polyamide using temperature and pH controlled adsorption–diffusion method via (a) selenization followed by (b) the exposure to the group III metal (Tl) salt solution and their surface morphological, chemical and crystalline phase information was determined with particular focus on their corresponding structure–optical property relationship. XRD analysis yielded a complex crystalline phase distribution which correlated well with the optical and surface morphological properties measured. pH 11.3 and 80 °C yielded well defined, low structural disorder composite material surface. After annealing in N{sub 2} at 100 °C, polycrystalline PA-Tl{sub x}Se{sub y} composite materials yielded a single TlSe phase due to the enhanced diffusion and reaction of thallium ions into the polymer. The method described here can be used to synthesize variety of binary III–VI compounds diffused into the polymer at relatively low temperatures and low overall cost, thus providing for a flexible synthesis route for novel composite solar energy harvesting materials.

  12. Polyamide–thallium selenide composite materials via temperature and pH controlled adsorption–diffusion method

    International Nuclear Information System (INIS)

    Graphical abstract: Single phase polyamide–thallium selenide hybrid functional materials were synthesized for solar energy conversion. - Highlights: • Thallium selenide–polyamide composite materials surfaces synthesized. • Mixed phase composition confirmed by XRD. • Increased temperature resulted in a denser surface packing. • Urbach energies correlated with AFM showing decreased structural disorder. • Annealing in N2 at 100 °C yielded a single TlSe phase. - Abstract: Composite materials based on III–VI elements are promising in designing efficient photoelectronic devices, such as thin film organic–inorganic solar cells. In this work, TlSe composite materials were synthesized on a model polymer polyamide using temperature and pH controlled adsorption–diffusion method via (a) selenization followed by (b) the exposure to the group III metal (Tl) salt solution and their surface morphological, chemical and crystalline phase information was determined with particular focus on their corresponding structure–optical property relationship. XRD analysis yielded a complex crystalline phase distribution which correlated well with the optical and surface morphological properties measured. pH 11.3 and 80 °C yielded well defined, low structural disorder composite material surface. After annealing in N2 at 100 °C, polycrystalline PA-TlxSey composite materials yielded a single TlSe phase due to the enhanced diffusion and reaction of thallium ions into the polymer. The method described here can be used to synthesize variety of binary III–VI compounds diffused into the polymer at relatively low temperatures and low overall cost, thus providing for a flexible synthesis route for novel composite solar energy harvesting materials

  13. Characteristics of plutonium and americium contamination at the former U.K. atomic weapons test ranges at Maralinga and Emu

    Energy Technology Data Exchange (ETDEWEB)

    Burns, P.A.; Cooper, M.B.; Lokan, K.H.; Wilks, M.J.; Williams, G.A. [Australian Radiation Lab., Melbourne, VIC (Australia)

    1995-11-01

    Physico-chemical studies on environmental plutonium are described, which provide data integral to an assessment of dose for the inhalation of artificial actinides by Australian Aborigines living a semi-traditional lifestyle at Maralinga and Emu, sites of U.K. atomic weapons tests between 1953 and 1963. The most significant area, from a radiological perspective, is the area contaminated by plutonium in a series of ``one point`` safety trials in which large quantities of plutonium were dispersed explosively at a location known as Taranaki. The activity distribution of plutonium and americium with particle size is quite different from the mass distribution, as a considerably higher proportion of the activity is contained in the finer (inhalable) fraction than of the mass. Except in areas which were disturbed through ploughing during a cleanup in 1967, most the activity remains in the top 1 cm of the surface. Much of the activity is in particulate form, even at distances > 20 km from the firing sites, and discrete particles have been located even at distances beyond 100 km. Data are presented which permit the assessment of annual committed doses through the inhalation pathway, for Aborigines living a semi-traditional lifestyle in the areas affected by the Taranaki firings in particular. (author).

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

    International Nuclear Information System (INIS)

    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 241Am(III) and 238Pu(III)/(IV) at pH 4 to 6 and ionic strengths of 0.1 to 4

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

    International Nuclear Information System (INIS)

    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.

  16. Use of radioanalytical methods for determination of uranium, neptunium, plutonium, americium and curium isotopes in radioactive wastes

    International Nuclear Information System (INIS)

    Activated charcoal is a common type of radioactive waste that contains high concentrations of fission and activation products. The management of this waste includes its characterization aiming the determination and quantification of the specific radionuclides including those known as Difficult-to-Measure Radionuclides (RDM). The analysis of the RDM's generally involves complex radiochemical analysis for purification and separation of the radionuclides, which are expensive and time-consuming. The objective of this work was to define a methodology for sequential analysis of the isotopes of uranium, neptunium, plutonium, americium and curium present in a type of radioactive waste, evaluating chemical yield, analysis of time spent, amount of secondary waste generated and cost. Three methodologies were compared and validated that employ ion exchange (TI + EC), extraction chromatography (EC) and extraction with polymers (ECP). The waste chosen was the activated charcoal from the purification system of primary circuit water cooling the reactor IEA-R1. The charcoal samples were dissolved by acid digestion followed by purification and separation of isotopes with ion exchange resins, extraction and chromatographic extraction polymers. Isotopes were analyzed on an alpha spectrometer, equipped with surface barrier detectors. The chemical yields were satisfactory for the methods TI + EC and EC. ECP method was comparable with those methods only for uranium. Statistical analysis as well the analysis of time spent, amount of secondary waste generated and cost revealed that EC method is the most effective for identifying and quantifying U, Np, Pu, Am and Cm present in charcoal. (author)

  17. Use of radioactive methods for determination of uranium, neptunium, plutonium, americium and curium isotopes in waste radioactive

    International Nuclear Information System (INIS)

    Activated charcoal is a common type of radioactive waste that contains high concentrations of fission and activation products. The management of this waste includes its characterization aiming the determination and quantification of the specific radionuclides including those known as Difficult-to-Measure Radionuclides (RDM). The analysis of the RDM's generally involves complex radiochemical analysis for purification and separation of the radionuclides, which are expensive and time-consuming. The objective of this work was to define a methodology for sequential analysis of the isotopes of uranium, neptunium, plutonium, americium and curium present in a type of radioactive waste, evaluating chemical yield, analysis of time spent, amount of secondary waste generated and cost. Three methodologies were compared and validated that employ ion exchange (TI+EC), extraction chromatography (EC) and extraction with polymers (ECP). The waste chosen was the activated charcoal from the purification system of primary circuit water cooling the reactor IEA-R1. The charcoal samples were dissolved by acid digestion followed by purification and separation of isotopes with ion exchange resins, extraction and chromatographic extraction polymers. Isotopes were analyzed on an alpha spectrometer, equipped with surface barrier detectors. The chemical yields were satisfactory for the methods TI+EC and EC. ECP method was comparable with those methods only for uranium. Statistical analysis as well the analysis of time spent, amount of secondary waste generated and cost revealed that EC method is the most effective for identifying and quantifying U, Np, Pu, Am and Cm present in charcoal. (author)

  18. Migration of the fission products strontium, technetium, iodine, cesium, and the actinides neptunium, plutonium, americium in granitic rock

    International Nuclear Information System (INIS)

    Rock samples were taken from drilling cores in granitic and granodioritic rock, and small (2x2x2 cm) rock tablets from the drilling cores were exposed to a groundwater solution containing one of the studied elements at race levels. The concentration of the element versus penetration depth in the rock tablet was measured radiometrically. The sorption on the mineral faces and the migration into the rock was studied, by an autoradiographic technique. The cationic fission products strontium and cesium had apparent diffusivities of 10-13-10-14 m2/s. They migrate mainly in fissures or filled fractures containing e.g., calcite, epidote or chlorite or in veins with hgih capacity minerals (e.g. biotite). The anionic fission products iodine and technetium had apparent diffusivities of about 10-14 m2/s. These species migrate along mineral boundaries and in open fractures and to a minor extent in high capacity mineral veins. The migration of the actinides neptunium, plutonium and americium is very slow (in the mm-range after 2-3 years contact time). The apparent diffusivities were about 10-15 m2/s. The actinide migration into the rock was largely confined to fissures. (orig./HP)

  19. Distribution of plutonium, americium, and several rare earth fission product elements between liquid cadmium and LiCl-KCl eutectic

    International Nuclear Information System (INIS)

    Separation factors were measured that describe the partition between molten cadmium and molten LiCl-KCl eutectic of plutonium, americium, praseodymium, neodymium, cerium, lanthanum, gadolinium, dysprosium, and yttrium. The temperature range was 753-788 K, and the range of concentrations was that allowed by the sensitivity of the chemical analysis methods. Mean separation factors were derived for Am-Pu, Nd-Am, Nd-Pu, Nd-Pr, Gd-La, Dy-La, La-Ce, La-Nd, Y-La, and Y-Nd. Where previously published data were available, agreement was good. For convenience, the following series of separation factors relative to plutonium was derived by combining the measured separation factors: Pu, 1.00 (basis); Am, 1.54; Pr, 22.0; Nd, 23.4; Ce, 26; La, 70; Gd, 77; Dy, 270; Y, 3000. These data are used in calculating the distribution of the actinide and rare earth elements in the prochemical reprocessing of spent fuel from the Integral Fast Reactor. (orig.)

  20. Characteristics of plutonium and americium contamination at the former U.K. atomic weapons test ranges at Maralinga and Emu

    International Nuclear Information System (INIS)

    Physico-chemical studies on environmental plutonium are described, which provide data integral to an assessment of dose for the inhalation of artificial actinides by Australian Aborigines living a semi-traditional lifestyle at Maralinga and Emu, sites of U.K. atomic weapons tests between 1953 and 1963. The most significant area, from a radiological perspective, is the area contaminated by plutonium in a series of ''one point'' safety trials in which large quantities of plutonium were dispersed explosively at a location known as Taranaki. The activity distribution of plutonium and americium with particle size is quite different from the mass distribution, as a considerably higher proportion of the activity is contained in the finer (inhalable) fraction than of the mass. Except in areas which were disturbed through ploughing during a cleanup in 1967, most the activity remains in the top 1 cm of the surface. Much of the activity is in particulate form, even at distances > 20 km from the firing sites, and discrete particles have been located even at distances beyond 100 km. Data are presented which permit the assessment of annual committed doses through the inhalation pathway, for Aborigines living a semi-traditional lifestyle in the areas affected by the Taranaki firings in particular. (author)

  1. Measured solubilities and speciations of neptunium, plutonium, and americium in a typical groundwater (J-13) from the Yucca Mountain region

    International Nuclear Information System (INIS)

    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 237NpO2+, 239Pu4+, 241Am3+/Nd3+, and 243Am3+ 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

  2. Non-Stoichiometric Amorphous Indium Selenide Thin Films as a Buffer Layer for CIGS Solar Cells with Various Temperatures in Rapid Thermal Annealing.

    Science.gov (United States)

    Yoo, Myoung Han; Kim, Nam-Hoon

    2016-05-01

    The conventional structure of most of copper indium gallium diselenide (Culn(1-x)Ga(x)Se2, CIGS) solar cells includes a CdS thin film as a buffer layer. Cd-free buffer layers have attracted great interest for use in photovoltaic applications to avoid the use of hazardous and toxic materials. The RF magnetron sputtering method was used with an InSe2 compound target to prepare the indium selenide precursor. Rapid thermal annealing (RTA) was conducted in ambient N2 gas to control the concentration of volatile Se from the precursor with a change in temperature. The nature of the RTA-treated indium selenide thin films remained amorphous under annealing temperatures of ≤ 700 degrees C. The Se concentration of the RTA-treated specimens demonstrated an opposite trend to the annealing temperature. The optical transmittance and band gap energies were 75.33% and 2.451-3.085 eV, respectively, and thus were suitable for the buffer layer. As the annealing temperature increased, the resistivity decreased by an order-of-magnitude from 10(4) to 10(1) Ω-cm. At lower Se concentrations, the conductivity abruptly changed from p-type to n-type without crystallite formation in the amorphous phase, with the carrier concentration in the order of 10(17) cm(-3). PMID:27483873

  3. The new mineral species brodtkorbite, Cu2HgSe2, and the associated selenide assemblage from Tuminico, Sierra de Cacho, La Rioja, Argentina

    International Nuclear Information System (INIS)

    Brodtkorbite, ideally Cu2HgSe2, a new mineral species, occurs in a telethermal selenide vein-type assemblage at the Tuminico Ia selenium deposit, Sierra de Cacho (Sierra de Umango) district, La Rioja, Argentina. The selenide assemblage also contains berzelianite, bellidoite, cadmoselite (mercurian, cuprian), chameanite, crookesite, eskebornite, eucairite, ferroselite, hakite, klockmannite, a luanheite-type phase, trogtalite-krutaite, tiemannite, tyrrellite, umangite and uraninite. Minor constituents are undefined phases that belong to the Cd-(Cu)-Hg-Se and (Co,Ni,Cu)-As-Se systems. The selenides occur as veinlets, as impregnations and as massive ores in calcite veins, and are hosted by altered (hematite-stained) amphibolites of the Sierra de Pampeanas, the Precambrian basement of the Precordillera terrane. Brodtkorbite was observed as anhedral grains; they range in size from 10 X 20 up to 50 X 100 μm and as aggregates of composite grains up to 150 X 250 μm, commonly intergrown with berzelianite, tiemannite and (rarely) umangite and clausthalite. The mineral is dark grey, opaque, has a metallic luster, and a dark grey streak. VHN10 ranges from 91.4 to 131 (mean 118) kg/mm2, which corresponds to a calculated Mohs hardness of about 2 1/2 to 3. The density is 7.77 g/cm3 and was calculated for the ideal formula with Z = 2, In plane-polarized reflected light, the mineral is white, is weakly to moderately pleochroic from pinkish to bluish white, and lacks internal reflections. It has a weak to strong bireflectance; the anisotropy is weak to strong with rotation tints from mauve-grey to yellowish grey. The reflectance spectra and color values in air and in oil are tabulated. The chemical composition, which was obtained with an electron microprobe, shows very little variation within individual grains and between grains. The average composition is: Cu 26.2, Hg 40.7, Se 32.9, total 99.8 wt%. This leads to an empirical formula (total atoms = 5) of Cu2.00Hg0.98Se2

  4. a Study of Volatile Precursors for the Growth of Cadmium Sulphide and Cadmium Selenide by Metal Organic Chemical Vapour Deposition.

    Science.gov (United States)

    Beer, Michael P.

    Available from UMI in association with The British Library. The wide-band-gap semiconductors, cadmium sulphide and cadmium selenide, may be grown by Metal Organic Chemical Vapour Deposition (MOCVD). This method typically involves the reaction of gaseous streams of Me_2 Cd and H_2Y (Y = S, Se) over a heated substrate (usually gallium arsenide) on which the desired compound is grown as an epitaxial layer. Unfortunately, the precursors start to react in the cold zone of the reactor, that is before they reach the heated substrate. This problem is known as prereaction. The problem of prereaction is partially reduced by the use of adducts of dimethyl cadmium in place of the free dialkyl compound although the mechanism by which such adducts block prereaction is unknown. Accordingly, a study of adducts of dimethyl cadmium was undertaken with a view to determining their properties in all phases. The adduct of Me_2Cd with 2,2^ '-bipyridyl was found to be monomeric in the solid state while that with 1,4-dioxane, a volatile compound used for prereaction reduction, was found to be polymeric. A study of adducts in the gas phase using mass spectrometry and gas phase Fourier transform infrared spectroscopy gave no evidence to suggest there is any gas phase association between 1,4-dioxane and dimethyl cadmium. With the 2,2 ^'-bipyridyl adduct some evidence for partial retention of coordinate bonds upon sublimation was obtained. The solid adduct of Me _2Cd with N,N,N^' ,N^'-tetramethylethylenediamine (TMEDA) was prepared as it was hoped that the flexibility of the aliphatic Lewis base would permit the formation of an adduct containing strong co-ordinate bonds which would remain intact upon sublimation. Using gas phase electron diffraction, the structure of the adduct of Me_2Cd and TMEDA was determined. It was shown to exist in the gas phase purely as the associated monomeric species. The adduct was then employed for the growth of CdS and CdSe in an industrial MOCVD apparatus. The

  5. The role of natural organic matter in the migration behaviour of americium in the Boom Clay - Part 1: migration experiments

    International Nuclear Information System (INIS)

    Full text of publication follows: In demonstrating the suitability of Boom Clay as reference site for studying the disposal of radioactive waste, the role of the relatively high amount of Natural Organic Matter (NOM) present in the Boom Clay on the mobility of critical radionuclides needs to be investigated thoroughly. It is generally accepted that trivalent actinides and lanthanides form strong complexes with humic substances. Complexation of these trivalent radionuclides with NOM present in the Boom Clay may therefore have two opposite effects. If complexed by the aqueous phase NOM (the mobile NOM), the radionuclide transport will be governed by the mobility of these dissolved radionuclide- NOM species. If complexed by the solid phase NOM (the immobile NOM) the migration will be retarded. One of the aims of the EC projects TRANCOM-Clay and TRANCOM-II was to investigate the role of mobile NOM as radionuclide carrier in order to develop a conceptual model for inclusion in a performance assessment (PA) model. The migration behaviour of Americium (used as an analogue for the critical radionuclide Pu) was investigated by complexing 241Am with radiolabelled (14C-labelled) NOM before passing through undisturbed Boom Clay cores contained in columns. The use of two different radionuclides, allows the migration behaviour of both the NOM and the Am to be followed. The results of the migration experiments showed that the Am-NOM complexes dissociated when they came into contact with Boom Clay and that the bulk of Am became immobilised (either as Am complexed to immobile NOM or sorbed to the mineral phase). Only a small percentage of the complex persisted as 'stabilised' Am-OM complex which exhibited slow dissociation kinetics upon moving through the Boom Clay. When the applied radionuclide source also contains Am in the form of an inorganic solid phase (when Am is applied above the solubility limit), a continuous source of Am exists to form 'temporarily stabilised' Am

  6. Molten salt extraction (MSE) of americium from plutonium metal in CaCl2-KCl-PuCl3 and CaCl2-PuCl3 salt systems

    International Nuclear Information System (INIS)

    Molten salt extraction (MSE) of americium-241 from reactor-grade plutonium has been developed using plutonium trichloride salt in stationary furnaces. Batch runs with oxidized and oxide-free metal have been conducted at temperature ranges between 750 and 945C, and plutonium trichloride concentrations from one to one hundred mole percent. Salt-to-metal ratios of 0.10, 0.15, and 0 30 were examined. The solvent salt was either eutectic 74 mole percent CaCl2 endash 26 mole percent KCl or pure CaCl2. Evidence of trivalent product americium, and effects of temperature, salt-to-metal ratio, and oxide contamination on the americium extraction efficiency are given. 24 refs, 20 figs, 13 tabs

  7. Plutonium, americium and radiocaesium in the marine environment close to the Vandellos I nuclear power plant before decommissioning

    International Nuclear Information System (INIS)

    The Vandellos nuclear power plant (NPP), releasing low-level radioactive liquid waste to the Mediterranean Sea, is the first to be decommissioned in Spain, after an incident which occurred in 1989. The presence, distribution and uptake of various artificial radionuclides (radiocaesium, plutonium and americium) in the environment close to the plant were studied in seawater, bottom sediments and biota, including Posidonia oceanica, fish, crustaceans and molluscs. Seawater, sediments and Posidonia oceanica showed enhanced levels in the close vicinity of the NPP, although the effect was restricted to its near environment. Maximum concentrations in seawater were 11.6±0.5 Bq m-3 and 16.9±1.2 mBq m-3 for 137Cs and 239,240Pu, respectively. When sediment concentrations were normalized to excess 210Pb, they showed both the short-distance transport of artificial radionuclides from the Vandellos plant and the long-distance transport of 137Cs from the Asco NPP. Posidonia oceanica showed the presence of various gamma-emitters attributed to the impact of the Chernobyl accident, on which the effect of the NPP was superimposed. Seawater, sediment and Posidonia oceanica collected near the plant also showed an enhancement of the plutonium isotopic ratio above the fallout value. The uptake of these radionuclides by marine organisms was detectable but limited. Pelagic fish showed relatively higher 137Cs concentrations and only in the case of demersal fish was the plutonium isotopic ratio increased. The reported levels constitute a set of baseline values against which the impact of the decommissioning operations of the Vandellos I NPP can be studied

  8. Determination by gamma-ray spectrometry of the plutonium and americium content of the Pu/Am separation scraps. Application to molten salts; Determination par spectrometrie gamma de la teneur en plutonium et en americium de produits issus de separation Pu/Am. Application aux bains de sels

    Energy Technology Data Exchange (ETDEWEB)

    Godot, A. [CEA Valduc, Dept. de Traitement des Materiaux Nucleaires, 21 - Is-sur-Tille (France); Perot, B. [CEA Cadarache, Dept. de Technologie Nucleaire, Service de Modelisation des Transferts et Mesures Nucleaires, 13 - Saint-Paul-lez-Durance (France)

    2005-07-01

    Within the framework of plutonium recycling operations in CEA Valduc (France), americium is extracted from molten plutonium metal into a molten salt during an electrolysis process. The scraps (spent salt, cathode, and crucible) contain extracted americium and a part of plutonium. Nuclear material management requires a very accurate determination of the plutonium content. Gamma-ray spectroscopy is performed on Molten Salt Extraction (MSE) scraps located inside the glove box, in order to assess the plutonium and americium contents. The measurement accuracy is influenced by the device geometry, nuclear instrumentation, screens located between the sample and the detector, counting statistics and matrix attenuation, self-absorption within the spent salt being very important. The purpose of this study is to validate the 'infinite energy extrapolation' method employed to correct for self-attenuation, and to detect any potential bias. We present a numerical study performed with the MCNP computer code to identify the most influential parameters and some suggestions to improve the measurement accuracy. A final uncertainty of approximately 40% is achieved on the plutonium mass. (authors)

  9. Recovery of plutonium and americium from laboratory acidic waste solutions using tri-n-octylamine and octylphenyl-N-N- diisobutylcarbamoylmethylphosphine oxide.

    Science.gov (United States)

    Michael, K M; Rizvi, G H; Mathur, J N; Kapoor, S C; Ramanujam, A; Iyer, R H

    1997-11-01

    Plutonium from acidic waste solutions has been recovered quantitatively using tri-n-octylamine (TnOA) in xylene and americium using a mixture of octylphenyl-N-N- diisobutylcarbamoylmethylphosphine oxide (CMPO) and TBP in dodecane by extraction and extraction chromatographic methods. The Pu ( IV ) TnOA species extracted into the organic phase from higher nitric acid concentrations has been confirmed as (R(3)NH)(2)Pu(NO(3))(6) (where R(3)N = TnOA by employing slope analysis as well as spectrophotometric studies. PMID:18966958

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

    DEFF Research Database (Denmark)

    Verma, Ashok K.; Modak, P.; Sharma, Surinder M.;

    2013-01-01

    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...... 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 respectiveU and α parameters. Low binding-energy peaks in the...

  11. Dissertation on the computer-based exploitation of a coincidence multi parametric recording. Application to the study of the disintegration scheme of Americium 241

    International Nuclear Information System (INIS)

    After having presented the meaning of disintegration scheme (alpha and gamma emissions, internal conversion, mean lifetime), the author highlights the benefits of the use of multi-parametric chain for the recording of correlated parameters, and of the use of a computer for the analysis of bi-parametric information based on contour lines. Using the example of Americium 241, the author shows how these information are obtained (alpha and gamma spectrometry, time measurement), how they are chosen, coded, analysed and stored, and then processed by contour lines

  12. Uptake of curium (244Cm) by five benthic marine species (Arenicola marina, Cerastoderma edule, Corophium volutator, Nereis diversicolor and Scrobicularia plana): comparison with americium and plutonium

    International Nuclear Information System (INIS)

    Curium (244Cm) uptake from contaminated sea water was studied in five benthic marine species: two bivalve molluscs (Scrobicularia plana and Cerastoderma edule), two polychaete annelids (Arenicola marina and Nereis diversicolor) and one amphidpod crustacean (Corophium volutator). The concentrations in the whole organisms relative to the concentration in the sea water (concentration factors) were: 700 for the amphipods (after 11 d of accumulation), 140 for the cockles (after 28 d), 80 for the scrobicularia (after 23d) and approx. 30 for the two annelids (after > 20 d). All species except S. plana accumulated americium and curium similarly; S. plana accumulated similar amounts of curium and plutonium. (author)

  13. Uptake of curium (/sup 244/Cm) by five benthic marine species (Arenicola marina, Cerastoderma edule, Corophium volutator, Nereis diversicolor and Scrobicularia plana): comparison with americium and plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Miramand, P.; Germain, P.; Arzur, J.C.

    1987-01-01

    Curium (/sup 244/Cm) uptake from contaminated sea water was studied in five benthic marine species: two bivalve molluscs (Scrobicularia plana and Cerastoderma edule), two polychaete annelids (Arenicola marina and Nereis diversicolor) and one amphidpod crustacean (Corophium volutator). The concentrations in the whole organisms relative to the concentration in the sea water (concentration factors) were: 700 for the amphipods (after 11 d of accumulation), 140 for the cockles (after 28 d), 80 for the scrobicularia (after 23d) and approx. 30 for the two annelids (after > 20 d). All species except S. plana accumulated americium and curium similarly; S. plana accumulated similar amounts of curium and plutonium.

  14. Design and fabrication of anti-reflection coating on Gallium Phosphide, Zinc Selenide and Zinc Sulfide substrates for visible and infrared application

    Czech Academy of Sciences Publication Activity Database

    Vápenka, David; Václavík, Jan; Mokrý, Pavel

    Cedex: EDP Sciences, 2013 - (Šulc, M.; Kopecký, V.; Lédl, V.; Melich, R.; Skeren, M.), s. 00029. (Book Series: EPJ Web of Conferences. 48). ISSN 2100-014X. [OaM 2012 International Conference on Optics and Measurement. Liberec (CZ), 16.10.2012-18.10.2012] R&D Projects: GA MŠk(CZ) OE10003; GA MŠk(CZ) ED2.1.00/03.0079 Institutional support: RVO:61389021 Keywords : gallium phosphide * zinc selenide * zinc sulfide Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://www.epj-conferences.org/articles/epjconf/pdf/2013/09/epjconf_OAM2012_00029.pdf

  15. Investigation of solubility of cesium, strontium, barium, rare-earth, uranium and americium fluorides in acid nitrosyl fluoride (NOFx3HF)

    International Nuclear Information System (INIS)

    Solubility of Am and other elements, which are fission products, in acid nitrosylfluoride has been studied. Cesium fluoride has maximum solubility; uranium tetrafluoride is also noticeably soluble; americium trifluoride is practically insoluble; fluorides of rare earth elements are slightly soluble in NOFx3HF. Analysis of the solid phase obtained after treating the mixture of the above fluorides with acid nitrosylfluoride has shown that cesium fluoride reacts with NOFx3HF with the formation of an acid salt (CsFxHF), whereas fluorides of alkaline and rare earth elements remain unchanged. The behaviour of a mixture of cesium, barium, and lanthanum fluorides in the process of three-multiple treating with acid nitrosylfluoride has been studied. It is shown that more than 98% of cesium fluoride and 5% of barium fluoride pass into the mother liquor while lanthanum fluoride remains completely in the solid phase. The data on americium fluoride solubility in acid nitrosylfluoride have indicated that it behaves in the same way as fluorides of rare earth elements; it is practically insoluble in HOFx3HF

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

    International Nuclear Information System (INIS)

    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

  17. Tellurides, selenides and Bi-mineral assemblages from the Río Narcea Gold Belt, Asturias, Spain: genetic implications in Cu-Au and Au skarns

    Science.gov (United States)

    Cepedal, A.; Fuertes-Fuente, M.; Martín-Izard, A.; González-Nistal, S.; Rodríguez-Pevida, L.

    2006-07-01

    Gold ores in skarns from the Río Narcea Gold Belt are associated with Bi-Te(-Se)-bearing minerals. These mineral assemblages have been used to compare two different skarns from this belt, a Cu-Au skarn (calcic and magnesian) from the El Valle deposit, and a Au-reduced calcic skarn from the Ortosa deposit. In the former, gold mineralization occurs associated with Cu-(Fe)-sulfides (chalcopyrite, bornite, chalcocite-digenite), commonly in the presence of magnetite. Gold occurs mainly as native gold and electrum. Au-tellurides (petzite, sylvanite, calaverite) are locally present; other tellurides are hessite, clausthalite and coloradoite. The Bi-bearing minerals related to gold are Bi-sulfosalts (wittichenite, emplectite, aikinite, bismuthinite), native bismuth, and Bi-tellurides and selenides (tetradymite, kawazulite, tsumoite). The speciation of Bi-tellurides with Bi/Te(Se + S) ≤ 1, the presence of magnetite and the abundance of precious metal tellurides and clausthalite indicate fO2 conditions within the magnetite stability field that locally overlap the magnetite-hematite buffer. In Ortosa deposit, gold essentially occurs as native gold and maldonite and is commonly related to pyrrhotite and to the replacement of löllingite by arsenopyrite, indicating lower fO2 conditions for gold mineralization than those for El Valle deposit. This fact is confirmed by the speciation of Bi-tellurides and selenides (hedleyite, joséite-B, joséite-A, ikunolite-laitakarite) with Bi/Te(+ Se + S) ≥ 1.

  18. Inhaled americium dioxide

    International Nuclear Information System (INIS)

    This project includes experiments to determine the effects of Zn-DTPA therapy on the retention, translocation and biological effects of inhaled 241AmO2. Beagle dogs that received inhalation exposure to 241AmO2 developed leukopenia, clincial chemistry changes associated with hepatocellular damage, and were euthanized due to respiratory insufficiency caused by radiation pneumonitis 120 to 131 days after pulmonary deposition of 22 to 65 μCi 241Am. Another group of dogs that received inhalation exposure to 241AmO2 and were treated daily with Zn-DTPA had initial pulmonary deposition of 19 to 26 μCi 241Am. These dogs did not develop respiratory insufficiency, and hematologic and clinical chemistry changes were less severe than in the non-DTPA-treated dogs

  19. Partitioning studies in China and the separation of americium and fission product rare earths with dialkyl phosphinic acid and its thio-substituted derivatives

    International Nuclear Information System (INIS)

    Studies on the TRPO extractions process for recovering actinides from highly active waste (HAW) and its application to the pretreatment of Chinese HAW are described. The removal of Sr by di-cyclohexyl 18 crown 6 and the removal of Cs by spherical titanium ferrous hexa-cyanate from acidic waste are also described. Results of the extraction of trivalent americium and fission product rare earths (FPREs) by dialkyl-phosphinic, dialkyl-mono-thio-phosphinic and dialkyl-di-thio-phosphinic acids are reported. Dialkyl-thio-phosphinic acid (commercial product Cyanex 301, alkyl =2, 4, 4-methyl-pentyl) shows very high selectivity towards Am. Using 1M Cyanex 301 -kerosene as extractant, 99.9 % Am can be separated from 0.5M(Pr+Nd)(NO3)3 solution with 3-4 extraction stages and 3-4 scrubbing stages. (authors)

  20. Theoretical and experimental study of the bio-geochemical behaviour of americium 241 in simplified rhizosphere conditions. Application to a calcareous agricultural soil

    International Nuclear Information System (INIS)

    Americium 241, is one of the most radio-toxic contaminant produced during the nuclear fuel cycle. It can be found in all environmental compartments, in particular the soils. The main goals of this study are to identify, quantify and model the effect of the main factors controlling the mobility of 241Am in the rhizosphere and the agricultural soils. The physico-chemical parameters of the soil and of the soil solution, the potential role of microorganisms on the sorption-desorption processes, and the speciation of americium in solution have been more particularly studied. 241Am remobilization has been studied at the laboratory using leaching experiments performed in controlled conditions on reworked calcareous soils artificially contaminated with 241Am. The soil samples have been washed out in different hydrodynamic conditions by solutions with various compositions. The eluted solution has been analyzed (pH, conductivity, ionic composition, Fetot, organic acids, 241Am) and its bacterial biomass content too. The overall results indicate that 241Am remobilization is contrasted and strongly linked with the condition under study (pH, ionic strength, glucose and/or citrate concentration). Therefore, a solution in equilibrium with the soil or containing small exudate concentrations (10-4 M) re-mobilizes only a very small part of the americium fixed on the solid phase. The desorption of 241Am corresponds to a solid/liquid coefficient of partition (Kd) of about 105 L.kg-1. A significant addition of glucose induces an important dissolution of soil carbonates by the indirect action of microorganisms, but does not significantly favor the 241Am remobilization. On the other hand, the presence of strong citrate concentrations (≥ 10-2 M) allows 300 to 10000 time greater re-mobilizations by the complexing of 241Am released after the dissolution of the carrying phases. Finally, the colloidal transport of 241Am has been systematically observed in a limited but significant extend and

  1. An evaluation of the VM/VF ratio to standard UO2 and MOX fuel with 4,5% enrichment and 1% of americium insertion

    International Nuclear Information System (INIS)

    A growing interest exists in the development of techniques for burning and transmuting minor actinides. Some indicate the possibility of differentiated burnup when studying different VM/VF. The VM/VF ratio, moderator volume/fuel volume, is directly related with the value obtained for the multiplication factor k. There is a VM/VF for which k is maximum, and this is directly related with the fuel composition. This work is a study to find a better value of VM/VF, using the WIMS-D5 code, considering a UO2 fuel and a MOX fuel, with 1% Americium insertion. The following parameters were appraised: spectrum hardening, boron worth, and reactivity temperature coefficients. (author)

  2. Recovery of Americium-241 from lightning rod by the method of chemical treatment; Recuperacion del Americio-241 provenientes de los pararrayos por el metodo de tratamiento quimico

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, W.H., E-mail: wcruz@ipen.gob.pe [Instituto Peruano de Energia Nuclear (GRRA/IPEN), Lima (Peru). Division de Gestion de Residuos Radiactivos

    2013-07-01

    About 95% of the lightning rods installed in the Peruvian territory have set in their structures, pose small amounts of radioactive sources such as Americium-241 ({sup 241}Am), fewer and Radium 226 ({sup 226}Ra) these are alpha emitters and have a half life of 432 years and 1600 years respectively. In this paper describes the recovery of radioactive sources of {sup 241}Am radioactive lightning rods using the conventional chemical treatment method using agents and acids to break down the slides. The {sup 241}Am recovered was as excitation source and alpha particle generator for analysing samples by X Ray Fluorescence, for fixing the stainless steel {sup 241}Am technique was used electrodeposition. (author)

  3. Preliminary application of 241-Americium calcaneus bone mineral density measurement in osteoporosis. Comparison with double X-ray densitometry of the lumber spine

    International Nuclear Information System (INIS)

    Bone mineral density (BMD) of calcaneus in 54 normals, 45 Osteoporosis, 25 suspected osteoporosis and 16 other non-osteoporosis patients, a total of 140 cases were measured by HUAKE (HK-1) 241-Americium BMD absorpmetry, among them 43 were compared with that of lumber spine (L2 - L4) measured by Lunar Corporation's Expert-XL absorpmeter. BMD of normal group of calcaneus was (409.8 +- 79.4) mg/cm2. The BMD were decreased slowly with the increasing age. The BMD of osteoporosis, suspected osteoporosis and non-osteoporosis group were 230.3 +- 62.3, 395.7 +- 57.4 and 363.3 +- 51.9 mg/cm2 respectively. The BMD of osteoporosis group was much lower than that of normal group, and also lower than that of the other two groups, among 26 patients (57.78%) had bone fracture, all was in accordance with the clinical diagnosis of osteoporosis. The BMD of suspected osteoporosis and non-osteoporosis had no significant difference with normal group. The coefficient variation (CV) of BMD in repeated measurement in calcaneus of 4 participants was less than 1.2%. The correlative coefficient (r) between BMD of calcaneus and lumber spine (L2 - L4) group was 0.6824. The correlative coefficient of normal young adult-matched percentage and T value in 2 groups were 0.6863 and 0.6755 respectively, whereas aged-matched percentage, Z value were 0.4614 and 0.5009 respectively. In conclusion 241-Americium calcaneus BMD absorpmetry has the advantage of low price, easy to operate, reliable and valuable in diagnosis osteoporosis. The correlations of calcaneus and lumber spine BMD, normal young adult-matched percentage and T value were rather good

  4. Safe handling of kilogram amounts of fuel-grade plutonium and of gram amounts of plutonium-238, americium-241 and curium-244

    International Nuclear Information System (INIS)

    During the past 10 years about 600 glove-boxes have been installed at the Institute for Transuranium Elements at Karlsruhe. About 80% of these glove-boxes have been designed and equipped for handling 100-g to 1-kg amounts of 239Pu containing 8-12% 240Pu (low-exposure plutonium). A small proportion of the glove-boxes is equipped with additional shielding in the form of lead sheet or lead glass for work with recycled plutonium. In these glove-boxes gram-amounts of 241Am have also been handled for preparation of Al-Am targets using tongs and additional shielding inside the glove-boxes themselves. Water- and lead-shielded glove-boxes equipped with telemanipulators have been installed for routine work with gram-amounts of 241Am, 243Am and 244Cm. A prediction of the expected radiation dose for the personnel is difficult and only valid for a preparation procedure with well-defined preparation steps, owing to the fact that gamma dose-rates depend strongly upon proximity and source seize. Gamma radiation dose measurements during non-routine work for 241Am target preparation showed that handling of gram amounts leads to a rather high irradiation dose for the personnel, despite lead or steel glove-box shielding and shielding within the glove-boxes. A direct glove-hand to americium contact must be avoided. For all glove-handling of materials with gamma radiation an irradiation control of the forearms of the personnel by, for example, thermoluminescence dosimeters is necessary. Routine handling of americium and curium should be executed with master-slave equipment behind neutron and gamma shielding. (author)

  5. Cadmium telluride (CdTe) and cadmium selenide (CdSe) leaching behavior and surface chemistry in response to pH and O2.

    Science.gov (United States)

    Zeng, Chao; Ramos-Ruiz, Adriana; Field, Jim A; Sierra-Alvarez, Reyes

    2015-05-01

    Cadmium telluride (CdTe) and cadmium selenide (CdSe) are increasingly being applied in photovoltaic solar cells and electronic components. A major concern is the public health and ecological risks associated with the potential release of toxic cadmium, tellurium, and/or selenium species. In this study, different tests were applied to investigate the leaching behavior of CdTe and CdSe in solutions simulating landfill leachate. CdTe showed a comparatively high leaching potential. In the Toxicity Characteristic Leaching Procedure (TCLP) and Waste Extraction Test (WET), the concentrations of cadmium released from CdTe were about 1500 and 260 times higher than the regulatory limit (1 mg/L). In contrast, CdSe was relatively stable and dissolved selenium in both leaching tests was below the regulatory limit (1 mg/L). Nonetheless, the regulatory limit for cadmium was exceeded by 5- to 6- fold in both tests. Experiments performed under different pH and redox conditions confirmed a marked enhancement in CdTe and CdSe dissolution both at acidic pH and under aerobic conditions. These findings are in agreement with thermodynamic predictions. Taken as a whole, the results indicate that recycling of decommissioned CdTe-containing devices is desirable to prevent the potential environmental release of toxic cadmium and tellurium in municipal landfills. PMID:25710599

  6. Synthesis, characterization and electrochemical characterization of lead selenide sub-micron particles capped with a benzoate ligand and prepared at different temperatures

    International Nuclear Information System (INIS)

    Semiconductor materials offer several potential benefits as active elements in the development of harvesting-energy conversion technologies. In particular, lead selenide (PbSe) semiconductors have been used and proposed to design solar energy harvesting devices, IR sensors, FET devices, etc. Lead salts have drawn particular attention from the applied and fundamental research communities due to their exceptionally strong quantum confinement effects. Several syntheses of PbSe have been proposed using long chain surfactants to allow the formation of particles and nanoparticles. Here we present a synthesis using benzoic acid as the capping ligand in ambient atmosphere. Although the particles are not in nanometric size, we compare the crystal structure (using x-ray powder diffraction data), the near infrared and mid-infrared absorption properties of PbSe using oleic acid as the capping ligand with PbSe using benzoic acid as the capping ligand. The new synthetized particles were shown to have similar crystal structure and absorb light in the near infrared region at 1410 nm. We also performed cyclic voltammetry of these particles drop-casted in the surface of a glassy carbon electrode. The particles showed electrochemical behavior with an oxidation peak near (−402 ± 5 mV) versus Ag/AgCl reference electrode. The particles seem to form a polymeric film at the surface of a glassy carbon electrode. (paper)

  7. Electronic characterization of defects in narrow gap semiconductors: Comparison of electronic energy levels and formation energies in mercury cadmium telluride, mercury zinc telluride, and mercury zinc selenide

    Science.gov (United States)

    Patterson, James D.; Li, Wei-Gang

    1995-01-01

    The project has evolved to that of using Green's functions to predict properties of deep defects in narrow gap materials. Deep defects are now defined as originating from short range potentials and are often located near the middle of the energy gap. They are important because they affect the lifetime of charge carriers and hence the switching time of transistors. We are now moving into the arena of predicting formation energies of deep defects. This will also allow us to make predictions about the relative concentrations of the defects that could be expected at a given temperature. The narrow gap materials mercury cadmium telluride (MCT), mercury zinc telluride (MZT), and mercury zinc selenide (MZS) are of interest to NASA because they have commercial value for infrared detecting materials, and because there is a good possibility that they can be grown better in a microgravity environment. The uniform growth of these crystals on earth is difficult because of convection (caused by solute depletion just ahead of the growing interface, and also due to thermal gradients). In general it is very difficult to grow crystals with both radial and axial homogeneity.

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

    Science.gov (United States)

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

    2016-03-01

    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. PMID:26907589

  9. 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

    International Nuclear Information System (INIS)

    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 241Am, 239,240Pu and 238U concentrations in well waters within the study area are in the range 0.04-87 mBq dm-3, 0.7-99 mBq dm-3, and 74-213 mBq dm-3, respectively, and for 241Am and 239,240Pu 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 0.01 mBq dm-3, 0.08 mBq dm-3 and 0.32 mBq dm-3 for 241Am, 239,240Pu and 238U, respectively. The 235U/238U 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 11-42 μSv (mean 21 μSv). Presently, the ground water feeding these wells would not appear to be contaminated with radioactivity from past

  10. Crystal and electronic structures of two new iron selenides: Ba{sub 4}Fe{sub 3}Se{sub 10} and BaFe{sub 2}Se{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Berthebaud, David, E-mail: david.berthebaud@ensicaen.fr [CNRS CRISMAT UMR6508, 6 Boulevard du Maréchal Juin, F-14050 CAEN Cedex 4 (France); Perez, Olivier [CNRS CRISMAT UMR6508, 6 Boulevard du Maréchal Juin, F-14050 CAEN Cedex 4 (France); Tobola, Janusz [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Pelloquin, Denis; Maignan, Antoine [CNRS CRISMAT UMR6508, 6 Boulevard du Maréchal Juin, F-14050 CAEN Cedex 4 (France)

    2015-10-15

    The new ternary selenides, Ba{sub 4}Fe{sub 3}Se{sub 10} and BaFe{sub 2}Se{sub 4,} were synthesized from a reaction of appropriate amounts of elements at high temperature in a silica sealed tube, and their structures were resolved using X-ray single crystal diffraction. BaFe{sub 2}Se{sub 4} crystallizes in the tetragonal space group I4/m with a=8.008(9) Å and c=5.483(3) Å as cell parameters. It is a new compound with a structure isotypical to the sulfide BaFe{sub 2}S{sub 4} which belongs to the infinitely adaptive structures series Ba{sub 1+x}Fe{sub 2}S{sub 4}. The second compound, Ba{sub 4}Fe{sub 3}Se{sub 10}, crystallizes in the monoclinic space group P2{sub 1}/n with a=8.8593(1) Å, b=8.8073(1) Å, c=12.2724(1) Å and β=109.037(6)° as cell parameters. It exhibits an original structure with a new type of iron selenide polyhedra. These data were consistent with the powder X-ray diffraction and TEM analyses. Their electronic structures point towards metallicity and electronic correlations for both selenides. - Graphical abstract: Experimental [010] oriented ED pattern and corresponding HREM image of Ba{sub 4}Fe{sub 3}Se{sub 10}. Image calculated with a focus and thickness to 15nm and 8 nm respectively is inserted. Bright contrasts are correlated to Se rows belonging to FeSe{sub 3}(Se{sub 2}){sup 2−}–FeSe{sub 6}–FeSe{sub 3}(Se{sub 2}){sup 2−} trimers. The corresponding structure projection is also shown. - Highlights: • Two new barium iron selenide compounds. • An original structure type Ba4Fe3Se10. • Electronic structure calculations.

  11. Microbial toxicity of ionic species leached from the II-VI semiconductor materials, cadmium telluride (CdTe) and cadmium selenide (CdSe).

    Science.gov (United States)

    Ramos-Ruiz, Adriana; Zeng, Chao; Sierra-Alvarez, Reyes; Teixeira, Luiz H; Field, Jim A

    2016-11-01

    This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox(®) test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC50) values obtained of 8.6 mg L(-1) for both cadmium and tellurite, 10.2 mg L(-1) for tellurate, and 24.1 mg L(-1) for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC50 values of 2.9 and 18.0 mg L(-1), respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox(®) analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L(-1), respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity. PMID:27494313

  12. The presence of mercury selenide in various tissues of the striped dolphin: evidence from μ-XRF-XRD and XAFS analyses.

    Science.gov (United States)

    Nakazawa, Emiko; Ikemoto, Tokutaka; Hokura, Akiko; Terada, Yasuko; Kunito, Takashi; Tanabe, Shinsuke; Nakai, Izumi

    2011-07-01

    Marine mammals accumulate mercury in their tissues at high concentration and detoxify by forming mercury selenide (HgSe, tiemannite) mainly in the liver. We investigated the possibility of formation of HgSe in various tissues (liver, kidney, lung, spleen, pancreas, muscle and brain) other than the liver of the striped dolphin (Stenella coeruleoalba). We applied a combination method of micro-X-ray fluorescence (μ-XRF) imaging and micro-X-ray diffraction (μ-XRD) using a synchrotron radiation X-ray microbeam to analyze the tissue samples directly with minimal sample preparation. By this method, many accumulation points for Hg and Se on a micron scale were found in thin sections of the spleen and liver tissue and consequently, the XRF spectra and the XRD pattern of the hot spots confirmed the presence of tiemannite, HgSe. On the other hand, the insoluble fractions after enzyme digestion of the nuclear and mitochondrial fractions of all tissues were subjected to X-ray absorption fine structure (XAFS) analysis. XAFS analysis confirmed the presence of HgSe in all the tissues examined (liver, kidney, lung, spleen, pancreas, muscle and brain) of the striped dolphin. The presence of HgSe in all the tissues examined suggests that Se would be involved in the detoxification process of Hg in various tissues other than the liver. This contribution seems to be large especially in the liver and spleen but relatively small in the kidney, pancreas and brain, because the proportion of insoluble fraction containing HgSe was lower in these tissues (25 to 46%). This is the first report on the presence of tiemannite HgSe in various tissues of marine mammals. PMID:21468440

  13. Determination of the some electronic parameters of nanostructure copper selenide and Cu/Cu3Se2/n-GaAs/In structure

    International Nuclear Information System (INIS)

    Highlights: • Introducing to a new degree of freedom in the control of effective barrier height by using Cu. • We want to experimentally observe whether or not the diode continues the ideality in the temperature range of 60–400 K. • We have modified the Richardson’s plot using the temperature dependent values of effective area of the patches. - Abstract: The nanostructure copper selenide thin film has been grown on n-type gallium arsenide substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) method. The film has been characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) measurements. X-ray diffraction analysis of the film confirms a polycrystalline with preferred orientation. The AFM and SEM micrographs of the film reveal smooth and uniform surface pattern without any dark pits, pinholes and microcracks. The Cu/Cu3Se2/n-GaAs/In structure has been thermally formed in evaporating system after the SILAR process. The electrical analysis of Cu/Cu3Se2/n-GaAs/In structure has been investigated by means of current–voltage (I–V) measurements in the temperature range of 60–400 K in dark conditions. The values of barrier height (BH) and ideality factor (n) ranged from 0.21 eV and 4.97 (60 K) to 0.83 eV and 1.14 (400 K), respectively. In the calculations, the electrical parameters of the experimental forward bias I–V characteristics of the Cu/Cu3Se2/n-GaAs/In with the homogeneity in the 60–400 K range have been explained by means of the thermionic emission (TE), considering Gaussian distribution (GD) of BH with linear bias dependence

  14. Electronic Characterization of Defects in Narrow Gap Semiconductors-Comparison of Electronic Energy Levels and Formation Energies in Mercury Cadmium Telluride, Mercury Zinc Telluride, and Mercury Zinc Selenide

    Science.gov (United States)

    Patterson, James D.

    1996-01-01

    We have used a Green's function technique to calculate the energy levels and formation energy of deep defects in the narrow gap semiconductors mercury cadmium telluride (MCT), mercury zinc telluride (MZT) and mercury zinc selenide (MZS). The formation energy is calculated from the difference between the total energy with an impurity cluster and the total energy for the perfect crystal. Substitutional (including antisite), interstitial (self and foreign), and vacancy deep defects are considered. Relaxation effects are calculated (with molecular dynamics). By use of a pseudopotential, we generalize the ideal vacancy model so as to be able to consider relaxation for vacancies. Different charge states are considered and the charged state energy shift (as computed by a modified Haldane-Anderson model) can be twice that due to relaxation. Different charged states for vacancies were not calculated to have much effect on the formation energy. For all cases we find deep defects in the energy gap only for cation site s-like orbitals or anion site p-like orbitals, and for the substitutional case only the latter are appreciably effected by relaxation. For most cases for MCT, MZT, MZS, we consider x (the concentration of Cd or Zn) in the range appropriate for a band gap of 0.1 eV. For defect energy levels, the absolute accuracy of our results is limited, but the precision is good, and hence chemical trends are accurately predicted. For the same reason, defect formation energies are more accurately predicted than energy level position. We attempt, in Appendix B, to calculate vacancy formation energies using relatively simple chemical bonding ideas due to Harrison. However, these results are only marginally accurate for estimating vacancy binding energies. Appendix C lists all written reports and publications produced for the grant. We include abstracts and a complete paper that summarizes our work which is not yet available.

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

    International Nuclear Information System (INIS)

    The paper presents a new sampling method for studying in-body radioactive contamination by bone-seeking radionuclides such as 90Sr, 239+240Pu, 238Pu, 241Am 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 238Pu 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 90Sr in-body contamination studies in general public. - Highlights: → Surgery for joint replacement as novel sampling method for studying in-body radioactive contamination. → Proposed way of sampling is not causing ethic doubts. → It is a convenient way of collecting human bone samples from global population. → The applied analytical radiochemical procedure for bone matrix is described in details. → The opposite patient age correlations trends were found for 90Sr (negative) and Pu, Am (positive).

  16. The estimation of reactions of hematopoietic systems of organisms to the effect, caused by americium and plutonium, of nuclear industry workers

    Energy Technology Data Exchange (ETDEWEB)

    Gasteva, G. N.; Ivanova, T. A.; Gordeeva, A. A.; Suvorova, L. A.; Molokanov, A. A.; Badine, I.

    2004-07-01

    Object of research are the workers having in an organism radioactive substance (Am-241 and Pu-239). The purpose of work was the estimation of reaction hemopoietic systems of an organism on influence of americium and plutonium at workers of the nuclear industry. At the surveyed contingent of persons the determined effects caused by total influence Am-241 and Pu-239 are ascertained; chronic radiation disease with development, besides diffusive a pneumoscleoris and a chronic toxic-chemical radiating bronchitis, reactions of system of blood, jet hepatopathy which frequency accrued with increase doses loadings and essentially did not depend on age. In peripheral blood on the foreground jet changes act: hyperglobulia, the tendency to neutrophilus leukocytosis, monocytosis, increase ESR, decrease (reduction ?/G of factor reflecting weight and processing of defeat bronchus and pulmonary of system. Stable downstroke in number thrombocytes and reticulocytes in peripheral blood, their direct dependence on a doze of an irradiation, reflect hypoplastic a background hemogenesis, caused by long influence incorporatedin a bone and a bone brain of radioactive substances. At cytologic research punctate a bone brain jet changes which are expressed in increase of functional activity erythro-and myelopoiesiscome to light and provide compensatory reaction of peripheral blood. At histologic research of a bone brain and a bone fabric attributes of development atrophic process which is expressed in reduction of volume parenchyma a bone brain (a fatty atrophy) and dysplasia to a bone fabric are observed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mietelski, Jerzy W., E-mail: jerzy.mietelski@ifj.edu.pl [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Cracow (Poland); Golec, Edward B. [Traumatology and Orthopaedic Clinic, 5th Military Clinical Hospital and Polyclinic, Independent Public Healthcare Facility, Wroclawska 1-3, 30-901 Cracow (Poland); Orthopaedic Rehabilitation Department, Chair of Clinical Rehabilitation, Faculty of Motor of the Bronislaw Czech' s Academy of Physical Education, Cracow (Poland); Department of Physical Therapy Basics, Faculty of Physical Therapy, Administration College, Bielsko-Biala (Poland); Tomankiewicz, Ewa [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Cracow (Poland); Golec, Joanna [Orthopaedic Rehabilitation Department, Chair of Clinical Rehabilitation, Faculty of Motor of the Bronislaw Czech' s Academy of Physical Education, Cracow (Poland); Physical Therapy Department, Institute of Physical Therapy, Faculty of Heath Science, Jagiellonian University, Medical College, Cracow (Poland); Nowak, Sebastian [Traumatology and Orthopaedic Clinic, 5th Military Clinical Hospital and Polyclinic, Independent Public Healthcare Facility, Wroclawska 1-3, 30-901 Cracow (Poland); Orthopaedic Rehabilitation Department, Chair of Clinical Rehabilitation, Faculty of Motor of the Bronislaw Czech' s Academy of Physical Education, Cracow (Poland); Szczygiel, Elzbieta [Physical Therapy Department, Institute of Physical Therapy, Faculty of Heath Science, Jagiellonian University, Medical College, Cracow (Poland); Brudecki, Kamil [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Cracow (Poland)

    2011-06-15

    The paper presents a new sampling method for studying in-body radioactive contamination by bone-seeking radionuclides such as {sup 90}Sr, {sup 239+240}Pu, {sup 238}Pu, {sup 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 {sup 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 {sup 90}Sr in-body contamination studies in general public. - Highlights: > Surgery for joint replacement as novel sampling method for studying in-body radioactive contamination. > Proposed way of sampling is not causing ethic doubts. > It is a convenient way of collecting human bone samples from global population. > The applied analytical radiochemical procedure for bone matrix is described in details. > The opposite patient age correlations trends were found for 90Sr (negative) and Pu, Am (positive).

  18. The recycling of the actinides neptunium, americium and curium in a fast power reactor to reduce the long term activity in a final store

    International Nuclear Information System (INIS)

    The starting point for the considerations and calculations given in this dissertation is the inevitable production of radioactive materials in the use of nuclear energy, which creates a considerable potential danger in a final store for a very long period. As one possibility of alleviating this problem, a concept for recycling the waste actinides neptunium, americium and curium was proposed. The waste actinides are separated in the reprocessing of burnt-up fuel elements and reach a further irradiation circuit. There they pass through the stages 'manufacture of irradiation elements', 'use in a fast power reactor' and reprocessing of irradiation elements' several times. In each irradiation and subsequent storage, about 17% of the waste actinides are removed by fission or by conversion into nuclides which can be reused as fuel, so that during the life of 40 years of the fast recycling reacor, the waste actinides can be reduced in mass by one half. In order to determine this mass reduction effect, a model calculation was developed, which includes the representation of the neutron physics and thermal properties of the reactor core and the storage and reprocessing of the irradiation elements. (orig./RB)

  19. Actinide and lanthanum accumulation by immobilized cells of a citrobacter sp. and application to the decontamination of solutions containing americium and plutonium

    International Nuclear Information System (INIS)

    Phosphatase-mediated metal bioaccumulation by a Citrobacter sp. underlies a bioprocess for the removal of heavy metals from solution, as cell-bound metal phosphate. Deposition of uranyl ion indicated a role in the biotechnological removal of americium and plutonium from wastes generated from the nuclear fuel cycle. Preliminary studies suggested a recalcitrance of tetravalent species of U(IV), Th(IV) and Zr(IV) and, by implication, Pu(IV), probably attributable to the stability of metal-ligand complexes in solution. Trials with the trivalent model, La(III), indicated probable bioaccumulation of Pu(III) and Am(III), which was confirmed by the removal of 241Am by cells immobilized in a cartridge incorporated into a flow supplemented with Am. Pu(V) and Pu(IV) wastes may be treatable via prior reduction to Pu(III), with simultaneous removal of the latter with the co-contaminant Am(III). An oxidative route, to Pu(VI), with desolubilization as HPuO2PO4 was also considered, but experiments using the analogous U(VI) (uranyl ion) demonstrated a greater efficiency of M(III) removal. Initial experiments utilized polyacrylamide gel-immobilized cells. 241Am removal also occurred with Citrobacter sp. immobilized as biofilm on reticulated foam supports, more amenable to large-scale processes

  20. Characterization of americium(III) and lanthanide(III) complexes in mixed solvent extraction systems containing a malonamide and a dialkyl-phosphoric acid

    International Nuclear Information System (INIS)

    In order to further reduce toxicity of nuclear waste, the French Commissariat a l'energie atomique et aux energies alternatives (CEA) is developing processes that allow separation of minor actinides from fission products. The DIAMEX (Diamide extraction) - SANEX (Selective actinide extraction) process is based on a mixture of two organic extractants: a malonamide, the N,N'-dimethyl-N,N'-dioctyl-hexyl-ethoxy-malonamide (DMDOHEMA) and a dialkyl-phosphoric acid, the di(2-ethylhexyl)phosphoric acid (HDEHP), dissolved in an alkane. The mechanisms of its extraction process are still not completely understood. Various complementary analytical techniques were used to identify and characterize americium(III) and lanthanide(III) metallic complexes formed in the organic phase after solvent extraction (UV-Visible, Infrared, NMR and Time Resolved Laser-Induced Fluorescence spectroscopy, as well as Electro-spray Ionization Mass Spectrometry). These speciation studies were performed under a variety of experimental conditions (influence of the extractants concentration, acidity of the aqueous phase..) and mixed species including the two extractants were observed. (authors)

  1. Extraction and chromatographic separation and concentration of plutonium and americium from natural matrices. Author-review of dissertation submitted for fulfillment of the scientific degree 'Philosophiae doctor' (PhD.)

    International Nuclear Information System (INIS)

    We followed the optimization of separation progress of americium (241Am) from environmental samples - soil from surroundings nuclear power plant Jaslovske Bohunice, in our work. Selection and optimization of separation progresses had to verify the condition for preparation of samples on spectral measurement with coprecipitation of americium or plutonium with NdF3 (undesirable presence of calcium, magnesium, lanthanides) and condition of spectral purity (spectral overlapping 228Th, 238Pu, 241Am and 222Rn of energy). Very important step was the realization of existing goal and learn suitable isolation techniques of plutonium. We are choosing technique separation of plutonium base upon amine liquid extraction, for a digest consider qualitative quantitative factor of separation. Extraction reagent has been Aliquat-336, which extracts nitric complex of plutonium [Pu(NO3)62-] from 7-8 M solution HNO3. Use method separate off quantitative the plutonium, thorium and uranium from americium. Background sample formed the sample of soil from surroundings Velke Kostolany. Real samples were sampling from surroundings of pollute river Dudvah. Average value mass activities of 239,240Pu in the background sample had value 0.28 ± 0.10 Bq · kg-1. Value mass activities of 239,240Pu in sample from surroundings river Dudvah were in the range (0,6 - 39.4) Bq · kg-1. Methodical side separation of americium we step by step by using ion exchange methods, liquid extraction with extraction reagent TOPO, or combination of them and extraction chromatography with TOPO. We find out: (a) on exchange procedure are suitable on obtainable basis extract tracer of radionuclide, also is very up to time. Optimal method was indicate techniques using the formation of rhodanide complex of americium, with following adsorption on stark acidity anionic exchanger (lanthanides were non-absorbing); (b) t liquid extraction formed emulsion, the third phase on the interface of phases. If we treat the molar of

  2. Optical phonons in nanostructured thin films composed by zincblende zinc selenide quantum dots in strong size-quantization regime: Competition between phonon confinement and strain-related effects

    International Nuclear Information System (INIS)

    Raman scattering in combination with optical spectroscopy and structural studies by X-ray diffraction was employed to investigate the phonon confinement and strain-induced effects in 3D assemblies of variable-size zincblende ZnSe quantum dots close packed in thin film form. Nanostructured thin films were synthesized by colloidal chemical approach, while tuning of the nanocrystal size was enabled by post-deposition thermal annealing treatment. In-depth insights into the factors governing the observed trends of the position and half-width of the 1LO band as a function of the average QD size were gained. The overall shifts in the position of 1LO band were found to result from an intricate compromise between the influence of phonon confinement and lattice strain-induced effects. Both contributions were quantitatively and exactly modeled. Accurate assignments of the bands due to surface optical (SO) modes as well as of the theoretically forbidden transverse optical (TO) modes were provided, on the basis of reliable physical models (such as the dielectric continuum model of Ruppin and Englman). The size-dependence of the ratio of intensities of the TO and LO modes was studied and discussed as well. Relaxation time characterizing the phonon decay processes in as-deposited samples was found to be approximately 0.38 ps, while upon post-deposition annealing already at 200 °C it increases to about 0.50 ps. Both of these values are, however, significantly smaller than those characteristic for a macrocrystalline ZnSe sample. - Graphical abstract: Optical phonons in nanostructured thin films composed by zincblende zinc selenide quantum dots in strong size-quantization regime: competition between phonon confinement and strain-related effects. - Highlights: • Phonon confinement vs. strain-induced effects in ZnSe 3D QD assemblies were studied. • Shifts of the 1LO band result from an intricate compromise between the two effects. • SO and theoretically forbidden TO modes were

  3. The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium

    Energy Technology Data Exchange (ETDEWEB)

    Ketelaer, Jens

    2010-06-14

    The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium: Nuclear masses are an important quantity to study nuclear structure since they reflect the sum of all nucleonic interactions. Many experimental possibilities exist to precisely measure masses, out of which the Penning trap is the tool to reach the highest precision. Moreover, absolute mass measurements can be performed using carbon, the atomic-mass standard, as a reference. The new double-Penning trap mass spectrometer TRIGA-TRAP has been installed and commissioned within this thesis work, which is the very first experimental setup of this kind located at a nuclear reactor. New technical developments have been carried out such as a reliable non-resonant laser ablation ion source for the production of carbon cluster ions and are still continued, like a non-destructive ion detection technique for single-ion measurements. Neutron-rich fission products will be available by the reactor that are important for nuclear astrophysics, especially the r-process. Prior to the on-line coupling to the reactor, TRIGA-TRAP already performed off-line mass measurements on stable and long-lived isotopes and will continue this program. The main focus within this thesis was on certain rare-earth nuclides in the well-established region of deformation around N {proportional_to} 90. Another field of interest are mass measurements on actinoids to test mass models and to provide direct links to the mass standard. Within this thesis, the mass of {sup 241}Am could be measured directly for the first time. (orig.)

  4. 6,6 '-bis (5,5,8,8-tetramethyl-5,6,7,8-tetra-hydro-benzo 1,2,4 triazine-3-yl) 2,2 ' bipyridine, an effective extracting agent for the separation of americium(III) and curium(III) from the lanthanides

    International Nuclear Information System (INIS)

    The extraction of americium(III), curium(III), and the lanthanides(III) from nitric acid by 6,6'- bis (5,5,8,8-tetramethyl-5,6,7,8-tetra-hydro-benzo[1,2,4]triazine-3-yl)-[2,2'] bipyridine (CyMe4-BTBP) has been studied. Since the extraction kinetics were slow, N,N'-dimethyl-N,N'-di-octyl-2-(2-hexyl-oxy-ethyl)malonamide (DMDOHEMA) was added as a phase transfer reagent. With a mixture of 0.01 M CyMe4-BTBP + 0.25 M DMDOHEMA in n -octanol, extraction equilibrium was reached within 5 min of mixing. At a nitric acid concentration of 1 M, an americium(III) distribution ratio of approx. 10 was achieved. Americium(III)/lanthanide(III) separation factors between 50 (dysprosium) and 1500 (lanthanum) were obtained. Whereas americium(III) and curium(III) were extracted as di-solvates, the stoichiometries of the lanthanide(III) complexes were not identified unambiguously, owing to the presence of DMDOHEMA. In the absence of DMDOHEMA, both americium(III) and europium(III) were extracted as di-solvates. Back-extraction with 0.1 M nitric acid was thermodynamically possible but rather slow. Using a buffered glycolate solution of pH=4, an americium(III) distribution ratio of 0.01 was obtained within 5 min of mixing. There was no evidence of degradation of the extractant, for example, the extraction performance of CyMe4-BTBP during hydrolysis with 1 M nitric acid did not change over a two month contact. (authors)

  5. Thermodynamic parameters of MeO2+ + H+ reversible MeO22+ + 1/2 H2 reaction for americium and neptunium ions in solution of potassium phosphotungstates

    International Nuclear Information System (INIS)

    Formal oxidation potentials of MeO22+-MeO2+ pair are measured for americium and neptunium ions in solutions of potassium phosphotungstates in 23-51 deg C temperature range at solution pH values equal to 1.0 and 4.0 by differential coulopotentiometric and potentiometric methods. Based on the data obtained Gibbs energy change values; enthalpies and enthropies for MeO2+ + H+ ↔ MeO22+ + 1/2H2 reaction are calculated

  6. Study on the Synthesis Processing and Content Determination of Corn Silk Polysaccharide Selenide%硒化玉米须多糖的工艺条件及硒含量测定研究

    Institute of Scientific and Technical Information of China (English)

    侯巍; 朱小庆; 楚婧; 高金波

    2012-01-01

    OBJECTIVE Using the polysaccharide from corn silk as the raw material, to study the selenizing process with sodium selenite. METHODS Selenizing conditions were established by single factor and orthogonal design; determining content of polysaccharide selenide by Se( IV )-KSCN-MV extraction spectrophotometry; characterizing the structure of polysaccharide selenide by IR. RESULTS The optimal conditions were: 70 ℃ reaction temperature, 8 hours reaction time, mass ratio of com silk polysaccharide to sodium selenite 1 : 1.2, 0.3% HNO3 of volume fraction. The average content of selenium in corn silk polysaccharide was over 3.17 mg·g‐1 and average yield was 35.72%. IR results showed that corn silk polysaccharide contained Se=O and Se-C. CONCLUSION Corn silk polysaccharide selenide is successfully synthesized and the study provides the foundation for further study and exploiting for corn silk.%目的 以玉米须多糖为原料,用亚硒酸钠进行玉米须多糖的硒化研究.方法 利用单因素和正交试验确立硒化的最佳工艺条件;利用硒-硫氰酸钾-甲基紫萃取光度法测定硒多糖中的硒含量,并通过红外光谱对硒多糖进行了初步表征.结果 最佳工艺条件为反应温度70℃,反应时间8h,玉米须多糖与亚硒酸钠质量比为1∶1.2,硝酸体积分数为0.3%,玉米须硒多糖中硒含量为3.17 mg·g-1,平均收率为35.72%.红外光谱显示:玉米须硒多糖中含有Se=O键和Se-C键.结论 利用该工艺成功合成了玉米须硒多糖,为玉米须的开发和利用奠定基础.

  7. Characteristics of some selenides and the physical-chemical condition of selenides and tellurides in the Jílové gold metallogenic concentration area,Czech Republic%捷克Jílové金矿集区中硒矿物的特征与硒化物-碲化物的形成物理化学条件

    Institute of Scientific and Technical Information of China (English)

    刘家军; 杨隆勃; 翟德高; 吴杰

    2013-01-01

    the Middle Ages. The important gold de-posits include the Pepf, Bohuliby, Radlik and Rotlev. They exist mainly in the Upper Proterozoic volcano-sed-iment of the Stechovice Group and the granodiorite of the Central Bohemian Pluton. There are three types of gold mineralization in the Jilovegold metallogenic concentration area: veins, stockworks, impregnation. Up to now, more than 70 minerals have been identified. They include not only sulfides and sulfosalts of Cu,Pb,Zn, Fe, As,Mo,Bi, Hg, Au, and Ag-bearing minerals,a variety of oxide,hydroxide, sulfate,carbonate, tungstate and silicate minerals but also telluride,halide, and native metals. Examination of ores by optical microscope, electron probe,X-ray surface scanning,has revealed that there are some selenides in the deposits. The diversity of mineral species in the ores and the occurrence of visible native gold minerals are the outstanding features of the gold deposit. Generally speaking, the more robust correlation is with the chalcogenidic environment and, in most cases, the lesser correlation with specific minerals. Therefore, the highly enrichment of selenide and telluride in the deposits is very characteristic, reflecting a specific condition of their formation. In the early stage of mineralization, f(Se2), f(Te2) and f(O2) are relatively low while f(S2) is relatively high, with f(S2)/f(Se2)>1 and f(S2>/f(Te2)>1. In this circumstance, sulfur would be precipitated as sulfides while selenium and tellurium would tend to be trapped in the sulfides as isomorphous admixture. Therefore, the min-erals are characterized by the association of pyrite, marcasite, pyrrhotite, arsenopyrite, chalcopyrite, galenite, sphalerite and so on. In the late stage of mineralization, f(Se2), f(Te2), and f(O2) are relatively high while f(S2) is relatively low, with f(S2)/f(Se2)<1 and f(S2)/f(Te2)<1. In the main stage of mineralization, f(Se2 )/f(S2), f(Te2 )/f(S2) and f(O2) would increase with the precipitation of sulfides, which would

  8. Update of JAEA-TDB. Additional selection of thermodynamic data for solid and gaseous phases on nickel, selenium, zirconium, technetium, thorium, uranium, neptunium plutonium and americium, update of thermodynamic data on iodine, and some modifications

    International Nuclear Information System (INIS)

    We additionally selected thermodynamic data for solid and gaseous phases of nickel, selenium, zirconium, technetium, thorium, uranium, neptunium, plutonium and americium to our thermodynamic database JAEA-TDB for geological disposal of radioactive waste of high-level and TRU wastes. We thermodynamically obtained equilibrium constant from addition and subtraction of Gibbs free energy of formation on nickel, selenium, zirconium, technetium, thorium, uranium, neptunium plutonium and americium, which were selected in the Thermochemical Database Project by the Nuclear Energy Agency in the Organisation for Economic Co-operation and Development. Furthermore, we collected and updated thermodynamic data on iodine, changed master species of technetium(IV), and added thermodynamic data on selenium due to improving reliability of the thermodynamic database. We prepared text files of the updated thermodynamic database (JAEA-TDB) for geochemical calculation programs of PHREEQC, EQ3/6 and Geochemist's Workbench. These text files are contained in the attached CD-ROM and will be available on our Website (http://migrationdb.jaea.go.jp/). (author)

  9. Impact of the cation distribution homogeneity on the americium oxidation state in the U{sub 0.54}Pu{sub 0.45}Am{sub 0.01}O{sub 2−x} mixed oxide

    Energy Technology Data Exchange (ETDEWEB)

    Vauchy, Romain [CEA, DEN, DEC, Centre d’études nucléaires de Cadarache, Saint Paul Lez Durance 13108 (France); Robisson, Anne-Charlotte, E-mail: anne-charlotte.robisson@cea.fr [CEA, DEN, DEC, Centre d’études nucléaires de Cadarache, Saint Paul Lez Durance 13108 (France); Martin, Philippe M.; Belin, Renaud C.; Aufore, Laurence [CEA, DEN, DEC, Centre d’études nucléaires de Cadarache, Saint Paul Lez Durance 13108 (France); Scheinost, Andreas C. [Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Radiochemistry, P.O. Box 510119, 01314 Dresden, Germany and Rossendorf Beamline at ESRF, BP 220, F-38043 Grenoble (France); Hodaj, Fiqiri [Science et Ingénierie des Matériaux et Procédés (SIMaP, associé au CNRS UMR 5266 – UJF/INP-Grenoble), Domaine Universitaire, 1130 rue de la piscine, BP 75, 38402 Saint Martin d’Hères (France)

    2015-01-15

    The impact of the cation distribution homogeneity of the U{sub 0.54}Pu{sub 0.45}Am{sub 0.01}O{sub 2−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{sup −} decay of {sup 241}Pu. 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.

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

    Science.gov (United States)

    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.

  11. Fabrication of targets for transmutation of americium : synthesis of inertial matrix by sol-gel method. Procedure study on the infiltration of a radioactive solutions

    International Nuclear Information System (INIS)

    addition a new and unexpected phase formed by the reaction of americium with spinel during the high temperature synthesis process has been identified. This new phase could provide a unique menas to stabilise Am in one particular oxidation state. (Author)

  12. Sorption and diffusion of cobalt, nickel, strontium, iodine, cesium and americium in natural fissure surfaces and drill core cups studied by autoradiography, 3

    International Nuclear Information System (INIS)

    This report summarizes the studies on sorption and diffusion of Cs, Sr, Co, Ni, Am and I in common rocks in Finnish bedrock carried out in laboratory experiments. Samples used in these studies were sections of drill cores containing filled and unfilled natural fracture surfaces and drill cores with a diamond drilled longitudinal cavity in the middle of the sample (drill core cups). Samples originated from the two nuclear power plant sites in Finland: tonalite and mica gneiss from Olkiluoto in Eurajoki and rapakivi granite from Haestholmen in Loviisa. The water used in the experiments was synthetic groundwater spiked at a time with one of the radionuclides: Cs-134, Sr-90, Co-60, Ni-63, Am-241 and I-125. Contact times from one week to one year were used to evaluate time dependence of diffusion. An autoradiographic method was used for determination of the penetration depths and diffusion pathways of elements. For determination of diffusion coefficients a quantitative computerized autoradiographic method was used to get the concentration profiles of the radionuclides in the drill cores. Sorption on natural fracture surfaces was more effective than on freshly drilled core samples. Filling materials on natural fracture surfaces, except calcite, increased sorption. The distribution coefficients for drill core cups were about the same as those for unfilled natural fracture surfaces after a contact time of one week and the sorption tendency of radionuclides was: Ka(Cs) > Ka(Co) > Ka(Am) > Ka(Ni) > Ka(Sr) > Ka(I). Radionuclides were observed to penetrate into fissures of the rock matrix and high-capacity minerals. Strontium was found as far as 35 mm in a filled natural fracture surface sample of rapakivi granite after a contact time of one year. The corresponding values were 3.0 mm for cesium, 2.1 mm for cobalt and 2.6 mm for nickel. For americium no diffusion could be observed (a-values for strontium was 6.6 x 10-16-1.1 x 10-13 m2/s, for cesium 4.7 x 10-16-7.2 x 10-15 m2/s

  13. Separation by sequential chromatography of americium, plutonium and neptunium elements: application to the study of trans-uranian elements migration in a European lacustrine system

    International Nuclear Information System (INIS)

    The nuclear tests carried out in the atmosphere in the Sixties, the accidents and in particular that to the power station of Chernobyl in 1986, were at the origin of the dispersion of a significant quantity of transuranic elements and fission products. The study of a lake system, such that of the Blelham Tarn in Great Britain, presented in this memory, can bring interesting answers to the problems of management of the environment. The determination of the radionuclides in sediment cores made it possible not only to establish the history of the depositions and consequently the origin of the radionuclides, but also to evaluate the various transfers which took place according to the parameters of the site and the properties of the elements. The studied transuranic elements are plutonium 238, 239-240, americium 241 and neptunium 237. Alpha emitting radionuclides, their determination requires complex radiochemical separations. A method was worked out to successively separate the three radioelements by using a same chromatographic column. Cesium 137 is the studied fission product, its determination is done by direct Gamma spectrometry. Lead 210, natural radionuclide, whose atmospheric flow can be supposed constant. makes it possible to obtain a chronology of the various events. The detailed vertical study of sediment cores showed that the accumulation mode of the studied elements is the same one and that the methods of dating converge. The cesium, more mobile than transuranic elements in the atmosphere, was detected in the 1963 and 1986 fallout whereas an activity out of transuranic elements appears only for the 1963 fallout. The activity of the 1963 cesium fallout is of the same order of magnitude as that of 1986. The calculation of the diffusion coefficients of the elements in the sediments shows an increased migration of cesium compared to transuranic elements. An inventory on the whole of the lake made it possible to note that the atmospheric fallout constitute the

  14. Americium behaviour in plastic vessels

    Energy Technology Data Exchange (ETDEWEB)

    Legarda, F.; Herranz, M. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Idoeta, R., E-mail: raquel.idoeta@ehu.e [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Abelairas, A. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain)

    2010-07-15

    The adsorption of {sup 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 {sup 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 {sup 241}Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.

  15. Americium behaviour in plastic vessels

    International Nuclear Information System (INIS)

    The adsorption of 241Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of 241Am 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 241Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.

  16. EURADOS action for determination of americium in skull measures in vivo and Monte Carlo simulation; Accion EURADOS para la determinacion de americio en craneo mediante medidas in-vivo y simulacion Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Ponte, M. A.; Navarro Amaro, J. F.; Perez Lopez, B.; Navarro Bravo, T.; Nogueira, P.; Vrba, T.

    2013-07-01

    From the Group of WG7 internal dosimetry of the EURADOS Organization (European Radiation Dosimetry group, e.V.) which It coordinates CIEMAT, international action for the vivo measurement of americium has been conducted in three mannequins type skull with detectors of Germanium by gamma spectrometry and simulation by Monte Carlo methods. Such action has been raised as two separate exercises, with the participation of institutions in Europe, America and Asia. Other actions similar precede this vivo intercomparison of measurement and modeling Monte Carlo1. The preliminary results and associated findings are presented in this work. The laboratory of the body radioactivity (CRC) of service counter of dosimetry staff internal (DPI) of the CIEMAT, it has been one of the participants in vivo measures exercise. On the other hand part, the Group of numerical dosimetry of CIEMAT is participant of the Monte Carlo2 simulation exercise. (Author)

  17. Critical and shielding parametric studies with the Monte Carlo code TRIPOLI to identify the key points to take into account during the transportation of blanket assemblies with high ratio of americium

    International Nuclear Information System (INIS)

    In the framework of French research program on Generation IV sodium cooled fast reactor, one possible option consists in burning minor actinides in this kind of Advanced Sodium Technological Reactor. Two types of transmutation mode are studied in the world : the homogeneous mode of transmutation where actinides are scattered with very low enrichment ratio in fissile assemblies and the heterogeneous mode where fissile core is surrounded by blanket assemblies filled with minor actinides with ratio of incorporated actinides up to 20%. Depending on which element is considered to be burnt and on its content, these minor actinides contents imply constraints on assemblies' transportation between Nuclear Power Plants and fuel cycle facilities. In this study, we present some academic studies in order to identify some key constraints linked to the residual power and neutron/gamma load of such kind of blanket assemblies. To simplify the approach, we considered a modeling of a 'model cask' dedicated to the transportation of a unique irradiated blanket assembly loaded with 20% of Americium and basically inspired from an existent cask designed initially for the damaged fissile Superphenix assembly transport. Thermal calculations performed with EDF-SYRTHES code have shown that due to thermal limitations on cladding temperature, the decay time to be considered before transportation is 20 years. This study is based on explicit 3D representations of the cask and the contained blanket assembly with the Monte Carlo code TRIPOLI/JEFF3.1.1 library and concludes that after such a decay time, the transportation of a unique Americium radial blanket is feasible only if the design of our model cask is modified in order to comply with the dose limitation criterion. (author)

  18. Improving the efficiency of copper indium gallium (Di-selenide (CIGS solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    Directory of Open Access Journals (Sweden)

    M. Burghoorn

    2014-12-01

    Full Text Available Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (Jsc and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-selenide (CIGS solar cells is also optically advantageous. Here, we experimentally demonstrate that the Jsc and efficiency of CIGS solar cells with an absorber layer thickness (dCIGS of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (nresist = 1.792 vs. nAZO = 1.913 at 633 nm to avoid large optical losses at the resist-AZO interface. On average, Jsc increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%. No trend towards a larger relative increase in Jsc with decreasing dCIGS was observed. Ergo, the increase in Jsc can be fully explained by the reduction in reflection, and we did not observe any increase in Jsc based on an increased photon path length.

  19. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Burghoorn, M.; Kniknie, B.; Deelen, J. van; Ee, R. van [The Netherlands Organisation for Applied Scientific Research (TNO), De Rondom 1, 5612 AP, Eindhoven (Netherlands); Xu, M. [The Netherlands Organisation for Applied Scientific Research (TNO), De Rondom 1, 5612 AP, Eindhoven (Netherlands); Delft University of Technology, Optics Group, Van der Waalsweg 8, 2628 CH, Delft (Netherlands); Vroon, Z. [The Netherlands Organisation for Applied Scientific Research (TNO), De Rondom 1, 5612 AP, Eindhoven (Netherlands); Zuyd Hogeschool, Nieuw Eyckholt 300, 6419 DJ, Heerlen (Netherlands); Belt, R. van de [Kriya Materials BV, Urmonderbaan 22, 6167 RD, Geleen (Netherlands); Buskens, P., E-mail: pascal.buskens@tno.nl, E-mail: buskens@dwi.rwth-aachen.de [The Netherlands Organisation for Applied Scientific Research (TNO), De Rondom 1, 5612 AP, Eindhoven (Netherlands); DWI – Leibniz Institute for Interactive Materials, Forckenbeckstrasse 50, 52056, Aachen (Germany)

    2014-12-15

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (J{sub sc}) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the J{sub sc} and efficiency of CIGS solar cells with an absorber layer thickness (d{sub CIGS}) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (n{sub resist} = 1.792 vs. n{sub AZO} = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, J{sub sc} increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in J{sub sc} with decreasing d{sub CIGS} was observed. Ergo, the increase in J{sub sc} can be fully explained by the reduction in reflection, and we did not observe any increase in J{sub sc} based on an increased photon path length.

  20. Thermodynamics of extraction of plutonium(IV) and americium(III) in polyethylene glycol (PEG) and (NH4)2SO4 based aqueous biphasic system (ABS) using 18-crown-6

    International Nuclear Information System (INIS)

    Extraction of plutonium(IV) and americium(III) using PEG-2000/(NH4)2SO4 (40% w/w of each) aqueous biphasic system (ABS) with 18-crown-6 (18-C-6) was studied at four different temperatures in the range of 288 to 318 K. The species extracted are identified to be [Pu.2(18-C-6)](SO4)2 and [Am.2(18-C-6)](SO4)1.5 for Pu(IV) and Am(III), respectively, by the slope ratio method. The thermodynamic parameters evaluated at 298 K by the temperature coefficient approach show that the reaction is favoured by decrease of enthalpy and counteracted by decrease in entropy in the case of Pu(IV) as well as Am(III). The large decrease in the enthalpy observed indicates that there is direct bonding of crown ether to the central metal atom i.e. the formation of inner sphere complex for both Pu(IV) and Am(III) and is similar to that reported previously for Pu(VI). The order of equilibrium constant K and ΔG value is Pu(IV) > Pu(VI) > Am(III) and this is in accordance with the axial charge experienced by the incoming ligand. (orig.)

  1. Use of radioactive methods for determination of uranium, neptunium, plutonium, americium and curium isotopes in waste radioactive; Utilizacao de metodos radioanaliticos para determinacao de isotopos de uranio, netunio, plutonio, americio e curio em rejeitos radioativos

    Energy Technology Data Exchange (ETDEWEB)

    Geraldo, Bianca

    2012-07-01

    Activated charcoal is a common type of radioactive waste that contains high concentrations of fission and activation products. The management of this waste includes its characterization aiming the determination and quantification of the specific radionuclides including those known as Difficult-to-Measure Radionuclides (RDM). The analysis of the RDM's generally involves complex radiochemical analysis for purification and separation of the radionuclides, which are expensive and time-consuming. The objective of this work was to define a methodology for sequential analysis of the isotopes of uranium, neptunium, plutonium, americium and curium present in a type of radioactive waste, evaluating chemical yield, analysis of time spent, amount of secondary waste generated and cost. Three methodologies were compared and validated that employ ion exchange (TI+EC), extraction chromatography (EC) and extraction with polymers (ECP). The waste chosen was the activated charcoal from the purification system of primary circuit water cooling the reactor IEA-R1. The charcoal samples were dissolved by acid digestion followed by purification and separation of isotopes with ion exchange resins, extraction and chromatographic extraction polymers. Isotopes were analyzed on an alpha spectrometer, equipped with surface barrier detectors. The chemical yields were satisfactory for the methods TI+EC and EC. ECP method was comparable with those methods only for uranium. Statistical analysis as well the analysis of time spent, amount of secondary waste generated and cost revealed that EC method is the most effective for identifying and quantifying U, Np, Pu, Am and Cm present in charcoal. (author)

  2. Solubility and speciation studies of waste radionuclides pertinent to geologic disposal at Yucca Mountain: Results on neptunium, plutonium and americium in J-13 groundwater; Letter report (R707): Reporting period, October 1, 1985--September 30, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Nitsche, H.; Standifer, E.M.; Lee, S.C.; Gatti, R.C.; Tucker, D.B.

    1988-01-01

    We have studied the solubilities of neptunium, plutonium, and americium in J-13 groundwater from Yucca Mountain (Nevada) at three temperatures and hydrogen ion concentrations. They are 25{degree}, 60{degree}C, and 90{degree}C and pH 5.9, 7.0, and 8.5. The results for 25{degree}C are from a study which we did during FY 1984. We included these previous results in the tables to give more information on the solubility temperature dependence; they were, however, done at only one pH (7.0). The solubilities were studied from oversaturation. The nuclides were added at the beginning of each experiment as NpO{sub 2}{sup +}, Pu{sup 4+}, and Am{sup 3+}. The neptunium solubility decreased with increasing temperature and with increasing pH. The soluble neptunium did not change oxidation state at steady state. The pentavalent neptunium was increasingly complexed by carbonate with increasing pH. All solids were crystalline and contained carbonate, except the solid formed at 90{degree}C and pH 5.9. We identified this solid as crystalline Np{sub 2}P{sub 5}. The 25{degree}C, pH 7 solid was Na{sub 3}NpO{sub 2}(CO{sub 3}){sub 2} {center_dot} nH{sub 2}O. Plutonium concentrations decreased with increasing temperature and showed no trend with pH. Pu(V) and Pu(VI) were the dominant oxidation states in the supernatant solution; as the amount of Pu(V) increased with pH, Pu(VI) decreed. The steady-state solids were mostly amorphous, although some contained a crystalline component. They contained Pu(IV) polymer and unknown carbonates.

  3. Optimization and photophysics of cadmium selenide nanoparticles

    International Nuclear Information System (INIS)

    CdSe nanocrystallites of different sizes were prepared in polyvinyl alcohol (PVA) photopolymer films. Particle sizes were optimized by variation in the Cd to Se ions ratio up to 16:1 as well as doping in PVA. X-ray diffraction shows that the degree of crystallinity of PVA was found to decrease due to doping with CdSe NPs and having a cubic unit cell. The UV-vis absorption spectra for the CdSe NPs in both solutions and PVA films showed blue shifts with increasing the ratio of Cd ion leading to the decrease of the particle size. The photoluminescence spectra resulting from 441.5 nm He-Cd excitation of CdSe NPs in PVA show the same behavior of absorption spectra. A blue shift in most of the FT-IR and FT-Raman bands of PVA was observed due to the interaction between PVA and CdSe NPs, which increase by decreasing the particle size. The conductivity of PVA was found to increase by decreasing the particle size of CdSe NPs

  4. Antimony selenide thin-film solar cells

    Science.gov (United States)

    Zeng, Kai; Xue, Ding-Jiang; Tang, Jiang

    2016-06-01

    Due to their promising applications in low-cost, flexible and high-efficiency photovoltaics, there has been a booming exploration of thin-film solar cells using new absorber materials such as Sb2Se3, SnS, FeS2, CuSbS2 and CuSbSe2. Among them, Sb2Se3-based solar cells are a viable prospect because of their suitable band gap, high absorption coefficient, excellent electronic properties, non-toxicity, low cost, earth-abundant constituents, and intrinsically benign grain boundaries, if suitably oriented. This review surveys the recent development of Sb2Se3-based solar cells with special emphasis on the material and optoelectronic properties of Sb2Se3, the solution-based and vacuum-based fabrication process and the recent progress of Sb2Se3-sensitized and Sb2Se3 thin-film solar cells. A brief overview further addresses some of the future challenges to achieve low-cost, environmentally-friendly and high-efficiency Sb2Se3 solar cells.

  5. Lead selenide quantum dot polymer nanocomposites

    International Nuclear Information System (INIS)

    Optical absorption and fluorescence properties of PbSe quantum dots (QDs) in an Angstrom Bond AB9093 epoxy polymer matrix to form a nanocomposite were investigated. To the authors’ knowledge, this is the first reported use of AB9093 as a QD matrix material and it was shown to out-perform the more common poly(methyl methacrylate) matrix in terms of preserving the optical properties of the QD, resulting in the first reported quantum yield (QY) for PbSe QDs in a polymer matrix, 26%. The 1-s first excitonic absorption peak of the QDs in a polymer matrix red shifted 65 nm in wavelength compared to QDs in a hexane solution, while the emission peak in the polymer matrix red shifted by 38 nm. The fluorescence QY dropped from 55% in hexane to 26% in the polymer matrix. A time resolved fluorescence study of the QDs showed single exponential lifetimes of 2.34 and 1.34 μs in toluene solution and the polymer matrix respectively. (paper)

  6. The proliferation potential of neptunium and americium

    International Nuclear Information System (INIS)

    It is recognized that some trans-uranic elements other than plutonium, in particular Np and Am, if will be available in sufficient quantities, could be used for nuclear explosive devices. The spent fuel has been accumulating in number of nuclear power plant and operation of large scale commercial reprocessing plants. However, these materials are not covered by the definition of special fissionable material in the Agency Statute. At the time when the Statute was adopted, the availability of meaningful quantities of separated Np and Am was remote and they were not included in the definition of special fissionable material. Then, IAEA Board decided a measure for control of Np and Am on September 1999. This report contains the control method and the characteristic of Np and Am for using domestic nuclear industries, and it can be useful for understanding how to report and account of Np and Am. (author)

  7. The proliferation potential of neptunium and americium

    Energy Technology Data Exchange (ETDEWEB)

    An, J. S.; Shin, J. S.; Kim, J. S.; Kwack, E. H.; Kim, B. K

    2000-05-01

    It is recognized that some trans-uranic elements other than plutonium, in particular Np and Am, if will be available in sufficient quantities, could be used for nuclear explosive devices. The spent fuel has been accumulating in number of nuclear power plant and operation of large scale commercial reprocessing plants. However, these materials are not covered by the definition of special fissionable material in the Agency Statute. At the time when the Statute was adopted, the availability of meaningful quantities of separated Np and Am was remote and they were not included in the definition of special fissionable material. Then, IAEA Board decided a measure for control of Np and Am on September 1999. This report contains the control method and the characteristic of Np and Am for using domestic nuclear industries, and it can be useful for understanding how to report and account of Np and Am. (author)

  8. Evaluation of neutron data for americium-241

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, V.M.; Sukhovitskij, E.Sh.; Porodzinskij, Yu.V.; Klepatskij, A.B.; Morogovskij, G.B. [Radiation Physics and Chemistry Problems Inst., Minsk-Sosny (Belarus)

    1997-03-01

    The evaluation of neutron data for {sup 241}Am is made in the energy region from 10{sup -5} eV up to 20 MeV. The results of the evaluation are compiled in the ENDF/B-VI format. This work is performed under the Project Agreement CIS-03-95 with the International Science and Technology Center (Moscow). The Financing Party for the Project is Japan. The evaluation was requested by Y. Kikuchi (JAERI). (author). 60 refs.

  9. Recovery of americium by extraction chromatographic technique

    International Nuclear Information System (INIS)

    Acidic liquid waste (raffinate) was generated during continuous solvent extraction runs carried out in a countercurrent mode for the extraction of U(VI) and Pu(IV) by tri-isoamyl phosphate (TiAP) using an ejector mixer-settler. It contained Am (III) with a concentration of about 0.3 mg/mL in 1.6 M HNO3, over a volume of 2 liters. The objective of the present study was to develop a procedure for the recovery of Am from acidic solution and concentrate in a small volume. The compound, octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) was studied in detail for the extraction of actinides. Extraction chromatography is an important separation technique and is used for the recovery of various radionuclides

  10. Migration study of americium in porous medium

    International Nuclear Information System (INIS)

    Migration experiments of 241Am3+ had been performed by a column system, to investigate migration behavior of 241Am through a column packed porous sedimentary materials: a coastal sandy soil and a reddish soil. Most 241Am loaded into the column packed the reddish soil sorbed on the influent edge of the column. In the case of the sandy soil, however, considerable amount of 241Am was passed through the column. This shows that there is colloidal 241Am species which may move without effective interaction with the sandy soil. Such a migration behavior of colloidal 241Am in the sandy soil column could be evaluated by a sorption model based on filtration theory. Sorption mechanisms of 241Am on the sedimentary materials were examined by a chemical extraction method, for 241Am sorbed on the sandy soil and the reddish soil at any sections in the column. The 241Am sorbed on the reddish soil was mainly controlled by a reversible ion exchange reaction. On the other hand, the 241Am sorbed on the sandy soil ws controlled by irreversible reactions, such as the selective chemical sorptions onto Fe and Mn oxyhydroxide/oxide. The experimental results support that the migration of 241Am in the reddish soil layer can be estimated by using the Kd, whereas that in the sandy soil can not be explained by the Kd concept. (author)

  11. Fabrication of targets for transmutation of americium : synthesis of inertial matrix by sol-gel method. Procedure study on the infiltration of a radioactive solutions; Fabricacion de blancos para la transmutacion de americio: sintesis de matrices inertes por el metodo sol-gel. Estudio del procedimiento de infiltracion de disoluciones radiactivas

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Carretero, A. [Universidad Complutense de Madrid (Spain)

    2002-07-01

    made. In addition a new and unexpected phase formed by the reaction of americium with spinel during the high temperature synthesis process has been identified. This new phase could provide a unique menas to stabilise Am in one particular oxidation state. (Author)

  12. Preparation and superconductivity of iron selenide thin films.

    Science.gov (United States)

    Han, Y; Li, W Y; Cao, L X; Zhang, S; Xu, B; Zhao, B R

    2009-06-10

    FeSe(x) (x = 0.80,0.84,0.88,0.92) thin films were prepared on SrTiO(3)(001)(STO), (La,Sr)(Al,Ta)O(3)(001) (LSAT), and LaAlO(3)(001) (LAO) substrates by a pulsed laser deposition method. All of the thin films show single-phase and c-axis oriented epitaxial growth, and are superconducting. Among them, the FeSe(0.88) thin films show a T(c,onset) of 11.8 K and a T(c,0) of 3.4 K. The upper critical magnetic field is estimated to be 14.0 T. PMID:21825594

  13. Preparation and superconductivity of iron selenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Han, Y; Li, W Y; Cao, L X; Zhang, S; Xu, B; Zhao, B R [National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China)], E-mail: lxcao@aphy.iphy.ac.cn

    2009-06-10

    FeSe{sub x} (x = 0.80,0.84,0.88,0.92) thin films were prepared on SrTiO{sub 3}(001)(STO), (La,Sr)(Al,Ta)O{sub 3}(001) (LSAT), and LaAlO{sub 3}(001) (LAO) substrates by a pulsed laser deposition method. All of the thin films show single-phase and c-axis oriented epitaxial growth, and are superconducting. Among them, the FeSe{sub 0.88} thin films show a T{sub c,onset} of 11.8 K and a T{sub c,0} of 3.4 K. The upper critical magnetic field is estimated to be 14.0 T.

  14. Preparation and superconductivity of iron selenide thin films

    OpenAIRE

    Han, Y.; Li, W. Y.; Cao, L. X.; S. Zhang; Xu, B; Zhao, B. R.

    2009-01-01

    FeSex (x = 0.80, 0.84, 0.88, 0.92) thin films were prepared on SrTiO3(001) (STO), (La,Sr)(Al,Ta)O3(001) (LSAT), and LaAlO3(001) (LAO) substrates by pulsed laser deposition method. All thin films show single-phase and c-axis oriented epitaxial growth, and are superconducting. Among them, the FeSe0.88 thin films show Tc, onset of 11.8 K and Tc, 0 of 3.4 K. The upper critical magnetic field is estimated to be 14.0 T.

  15. Reversibility windows in selenide-based chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, O. [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska Street, Lviv, UA 79031 (Ukraine); Institute of Physics of Jan Dlugosz University, 13/15, al. Armii Krajowej, Czestochowa, PL 42200 (Poland); Hyla, M. [Institute of Physics of Jan Dlugosz University, 13/15, al. Armii Krajowej, Czestochowa, PL 42200 (Poland); Boyko, V. [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska Street, Lviv, UA 79031 (Ukraine); Lviv National Polytechnic University, 12, Bandera Street, Lviv, UA 79013 (Ukraine); Golovchak, R. [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska Street, Lviv, UA 79031 (Ukraine)], E-mail: golovchak@novas.lviv.ua

    2008-10-01

    A simple route for the estimation of the reversibility windows in the sense of non-ageing ability is developed for chalcogenide glasses obeying '8-N' rule at the example of As-Se, Ge-Se and Ge-As-Se glass systems. The low limit of their reversibility windows is determined at the average coordination number Z=2.4 in full agreement with rigidity percolation theory, while the upper limit is shown to be related to the glass preparation conditions and samples prehistory.

  16. Peculiarities of Ga and Te incorporation in glassy arsenic selenides

    OpenAIRE

    Golovchak, Roman; Shpotyuk, Yaroslav; Thomas, C M; Nazabal, Virginie; Boussard-Plédel, Catherine; Bureau, Bruno; Jain, Himanshu

    2015-01-01

    Effect of simultaneous Ga and Te addition on the structure of As2Se3 glasses is studied using X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) and Raman techniques. It is shown that most of As, Se and Te atoms build a covalent network according to their main valences. Three-fold coordinated As atoms form pyramidal structural units, which are connected via bridges of two-fold coordinated chalcogen atoms (Se, Te). On the other hand, coordination of Ga in ...

  17. Ab initio transport across bismuth selenide surface barriers

    KAUST Repository

    Narayan, Awadhesh

    2014-11-24

    © 2014 American Physical Society. We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi2Se3(111) topological surface states by means of large-scale ab initio transport simulations. Our results demonstrate the suppression of perfect backscattering, while all other scattering processes, which do not entail a complete spin and momentum reversal, are allowed. Furthermore, we find that the spin of the surface state develops an out-of-plane component as it traverses the barrier. Our calculations reveal the existence of quasibound states in the vicinity of the surface barriers, which appear in the form of an enhanced density of states in the energy window corresponding to the topological state. For double barriers we demonstrate the formation of quantum well states. To complement our first-principles results we construct a two-dimensional low-energy effective model and illustrate its shortcomings. Our findings are discussed in the context of a number of recent experimental works.

  18. Bath parameter dependence of chemically deposited Copper Selenide thin film

    International Nuclear Information System (INIS)

    In this article, a low cost chemical bath deposition (CBD) technique has been used for the preparation Of Cu2-xSe thin films on to glass substrate. Different thin fms (0.2-0.6/μm) were prepared by adjusting the bath parameter like concentration of ammonia, deposition time, temperature of the solution, and the ratios of the mixing composition between copper and selenium in the reaction bath. From these studies, it reveals that at low concentration of ammonia or TEA, the terminal thicknesses of the films are less, which gradually increases with the increase of concentrations and then drop down at still higher concentrations. It has been found that completing the Cu2+ ions with EA first, and then addition of ammonia yields better results than the reverse process. The film thickness increases with the decrease of value x of Cu2-xSe. (author)

  19. Electrolytically deposited Cadmium Selenide Films for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Palaiologopoulou M. D.

    2012-10-01

    Full Text Available CdSe films were electrodeposited on pure nickel substrates. The nickel substrate was polished to a mirror finish by Al2O3 paste, etched in 10% HCl solution for 40 s and rinsed thoroughly by de-ionized water. The deposition bath contained solutions with excessive Cd2+ (0.2M from CdSO4 and small amounts of SeO2 (1x10-3 M. The pH of the bath was adjusted to a value of 2.2 at RT by adding 10% H2SO4. The bath was first thermostated at the required temperature, which varied from 55°C to 65°C. Plating was accomplished at deposition potential 1000 mV (vs. Hg/Hg2SO4. The films formed had a uniform thickness and it was found to be approximately 2.0 μm thick (for 20 min electrodeposition process. The produced CdSe films were characterized by X-Ray diffraction and SEM. The induced semiconductor doping effect by thermal annealing in pure dry nitrogen gas was also investigated. Gold contacts were placed on top of the CdSe films, either by evaporation, or mechanically. Depending on the deposition parameters the electrical characteristics of the Ni/CdSe/Au structures may exhibit rectification properties. The optical excitation of the structure was investigated for various CdSe thicknesses.

  20. Synthesis, characterization, and electrical properties studies of cadmium selenide nanoparticle

    Science.gov (United States)

    Seoudi, R.; Elokr, M. M.; Shabaka, A. A.; Sobhi, A.

    2008-01-01

    A new solvothermal route was used for the preparation of CdSe nanoparticles at 160 °C for 10 h using ethylenediamine as a solvent. X-ray powder diffraction and transmission electron microscope were employed to characterize the size, morphology, and crystalline structure of the as-prepared sample. The formation process was discussed and it revealed a uniform hexagonal shape of CdSe nanoparticle with good dispersion, with an average size of 35 nm. Fourier transform infrared and ultraviolet-visible spectroscopies were used to follow the reaction and to determine the optical band gap. DC and AC electrical conductivities were studied and the activation energies were determined as well as the conduction mechanism. The results indicated that CdSe behaves as a semiconducting material. The dielectric properties were measured as a function of temperature at different frequencies ranging from 100 Hz to 100 kHz. The increase of the dielectric constant with increasing temperature was discussed on the basis of increasing polarizability, while its decrease with increasing frequency is attributed to the dielectric dispersion.

  1. Synthesis, characterization, and electrical properties studies of cadmium selenide nanoparticle

    International Nuclear Information System (INIS)

    A new solvothermal route was used for the preparation of CdSe nanoparticles at 160 deg. C for 10 h using ethylenediamine as a solvent. X-ray powder diffraction and transmission electron microscope were employed to characterize the size, morphology, and crystalline structure of the as-prepared sample. The formation process was discussed and it revealed a uniform hexagonal shape of CdSe nanoparticle with good dispersion, with an average size of 35 nm. Fourier transform infrared and ultraviolet-visible spectroscopies were used to follow the reaction and to determine the optical band gap. DC and AC electrical conductivities were studied and the activation energies were determined as well as the conduction mechanism. The results indicated that CdSe behaves as a semiconducting material. The dielectric properties were measured as a function of temperature at different frequencies ranging from 100 Hz to 100 kHz. The increase of the dielectric constant with increasing temperature was discussed on the basis of increasing polarizability, while its decrease with increasing frequency is attributed to the dielectric dispersion

  2. Selenide isotope generator for the Galileo Mission: safety test plan

    International Nuclear Information System (INIS)

    The intent of this safety test plan is to outline particular kinds of safety tests designed to produce information which would be useful in the safety analysis process. The program deals primarily with the response of the RTG to accident environments; accordingly two criteria were established: (1) safety tests should be performed for environments which are the most critical in terms of risk contribution; and (2) tests should be formulated to determine failure conditions for critical heat source components rather than observe heat source response in reference accident environments. To satisfy criterion 1. results of a recent safety study were used to rank various accidents in terms of expected source terms. Six kinds of tests were then proposed which would provide information meeting the second criterion

  3. Optical Properties of Nanoscale Bismuth Selenide and Its Heterocrystals

    Science.gov (United States)

    Vargas, Anthony

    Over the past 12 years since the groundbreaking work on graphene, the field of 2D layered materials has grown by leaps and bounds as more materials are theoretically predicted and experimentically verified. These materials and their unique electronic, optical, and mechanical properties have inspired the scientific community to explore and investigate novel, fundamental physical phenomena as well create and refine technological devices which leverage the host of unique benefits which these materials possess. In the past few years, this burgeoning field has heavily moved towards combining layers of various materials into novel heterostructures. These heterostructures are an exciting area of research because of the plethora of exciting possibilities and results which arise due to the large number of heterostructure combinations and configurations. Particularly, the research into the optical properties of these layered materials and their heterostructures under confinement provides another exciting avenue for developing optoelectric devices. In this dissertation, I present work on the synthesis of Bi2Se 3 nanostructures via chemical vapor deposition (CVD) and the study of the optical properties of these nanostructures and their heterostructures with MoS2. The bulk of the current published work on Bi2Se 3 has focused on the exotic topological properties of its surface states, both interesting fundamental physics purposes as well as for studying avenues for spintronics. In contrast, the work presented here focuses on studying the optical properties of Bi2Se3 nanostructures and how these properties evolve when subjected to confinement. Specifically, the absorbance of singlecrystal Bi2Se3 with sizes tailored down to a few nanometers in diameter and a few quintuple layers (QLs) in thickness. We find a dramatically large bandgap, Eg ≥ 2.5 eV, in the smallest particles which is much higher than that seen in 1QL measurements taken with ARPES. Additionally, utilizing photoluminescence (PL) measurements of CVD-grown Bi 2Se3 nanoplates with few QL thickness and effective diameters in the tens of nanometers, Bi2Se3 nanoplatelets show a strong PL response with photon energies, Eph, in the ˜2.1-2.3 eV region. Annealing of these samples at 200?C for 4 hours increases the PL intensity by a factor of 2.4 to 3 for nanoscale Bi2Se3. Furthermore, this work investigates the synthesis of the novel Bi2Se3-MoS 2 heterocrystal that arises from epitaxial growth of Bi2Se 3 on MoS2 substrates. These heterocrystals consist of n layers of Bi2Se3 perfectly rotationally-aligned epitaxially with the monolayer MoS2 substrate. Investigation into these heterocystals produced results which include 100% PL-suppression of the MoS2 PL response, precisely tunable band-gap ranging from 1.1eV ? 0.75 eV, and a spectacular wide-band enhancement of photo-absorption over nearly the entire solar spectral wavelengths. Finally, a simple laser-treatment appears to dramatically reverse these changes, attributed to breakdown of the rotational congruency between the MoS2 and Bi2Se3 layers. These heterocrystals have immense potentials for novel physics and applications in nanoelectronics, optoelectronics and energy sciences at the atomically-thin scale.

  4. Selenide isotope generator for the Galileo mission. GDS disassembly report

    International Nuclear Information System (INIS)

    The GDS-1 was disassembled to determine the cause for the rapid degradation of the output power. Unfortunately, it was not possible to relate the observations to direct causes for the degradation. However, some positive statements can be made which have an impact on the flight program. First, the outgassing and gas management techniques were shown to be adequate to maintain clean conditions within the generator. Second, the non-modular components within the generator including the receptacles on the housing were not affected by the thermal environment during operation of GDS-1. Third, a significant amount of sublimation of the P-legs has occurred during the relatively short life of 2000 + hours as shown by the bullet nosing of the legs and deposits on the cold end hardware. The fact that the generator atmosphere was not 100% xenon may have some bearing on this observation but the statement is still accurate. Fourth, all exposed N-legs display cracks and/or chips. Fifth, a great deal of misalignment of both N and P-legs was seen both visually and with radiographs. Although no definite conclusions can be made concerning the cause for the rapid degradation of performance, several of the observed conditions within the module could possibly contribute to that fact. They are: cracks in N-legs (increased resistance); deposits on edges of BeO discs (shorting of thermoelectric circuit); and bullet nosing of P-legs (increased resistance). It remains to be shown if any of these effects or the follower hangup described earlier contributed to the poor performance of GDS-1 or if another effect as yet unknown was the important factor

  5. Short-range order of germanium selenide glass

    Indian Academy of Sciences (India)

    A H Moharram

    2015-02-01

    Chalcogenide Ge20Se80 glass was prepared using the melt-quench technique. The radial distribution function is obtained from X-ray diffraction data in the scattering vector interval 0.28 ≤ ≤ 6.87 Å-1. ReverseMonte Carlo (RMC) simulations are useful to compute the partial pair distribution functions, $\\text{g}_{ij} (r)$, partial structure factors, $S_{ij} (K)$, and total structure factor. Values of $r_{1}/r_{2}$ ratio and bond angle () indicate that Ge(Se1/2)4 tetrahedra units connected by chains of the chalcogen atoms are present. The partial structure factors have shown that homopolar Ge–Ge and Se–Se bonds are behind the appearance of the first sharp diffraction peak (FSDP) in the total structure factor. Tetrahedral Ge(Se1/2)4 structural units connected by Se–Se chains have been confirmed by the simulated values of the partial coordination numbers and bond angle distributions. Finally, Raman spectra measurements have strongly supported the conclusions obtained either from the calculated Fourier data or from RMC simulations.

  6. MEASUREMENT OF NANOMETER SCALE CADMIUM SELENIDE NANOCRYSTALS AND CLUSTER MOLECULES

    Institute of Scientific and Technical Information of China (English)

    Jeffrey Yang

    2003-01-01

    High performance Dynamic Light Scattering (DLS) has been used to determine the hydrodynamic diameters of CdSe nanocrystals as well as CdSe cluster molecules in a size range of 1 to 10 nm (Eichh(o)fer et al., 2001).The method enables the determination of their particle size, including their ligand shells, in solution. The results are consistent with the blue shift of the absorption bands, as well as Transmission Electron Microscope (TEM) experiments.The sizes of the cluster molecules were estimated from space filling models constructed from the results of a single crystal X-ray structure determination. DLS gave comparable results for the size of both types of compound, indicating that it is potentially an important additional measurement technique to TEM, which uses harsh measurement conditions,and to powder X-ray diffraction, which is difficult to interpret below 5 nm.

  7. Potentiometric titration of excess cadmium in cadmium selenide

    International Nuclear Information System (INIS)

    A simple and rapid potentiometric technique for determining excess cadmium in CdSe has been developed. Reaction with AgNO3 is used for sample treatment. Silver, formed in the AgNO3 reaction with excess Cd is determined with the help of KI. When using the given method of analysis the relative standard deviation is equal to 0.08-0.21. The real detection limit of excess cadmium is 9x10-7 g

  8. Plutonium and americium behavior in coral atoll environments

    International Nuclear Information System (INIS)

    Inventories of 239+240Pu and 241Am greatly in excess of global fallout levels persist in the benthic environments of Bikini and Enewetak Atolls. Quantities of 239+240Pu and lesser amounts of 241Am are continuously mobilizing from these sedimentary reservoirs. The amount of 239+240Pu mobilized to solution at any time represents 0.08 to 0.09% of the sediment inventories to a depth of 16 cm. The mobilized 239+240Pu has solute-like characteristics and different valence states coexist in solution - the largest fraction of the soluble plutonium is in an oxidized form (+V,VI). The adsorption of plutonium to sediments is not completely reversible because of changes that occur in the relative amounts of the mixed oxidation states in solution with time. Further, any characteristics of 239+240Pu described at one location may not necessarily be relevant in describing its behavior elsewhere following mobilization and migration. The relative amounts of 241Am to 239+240Pu in the sedimentary deposits at Enewetak and Bikini may be altered in future years because of mobilization and radiological decay. Mobilization of 239+240Pu is not a process unique to these atolls, and quantities in solution derived from sedimentary deposits can be found at other global sites. These studies in the equatorial Pacific have significance in assessing the long-term behavior of the transuranics in any marine environment. 22 references, 1 figure, 13 tables

  9. Complex formation of americium (III) with humic acid

    International Nuclear Information System (INIS)

    The presence of humic substances in natural waters will modify the migration behavior of actinides in the geosphere due to the strong reaction properties of these ligands with actinides. Therefore, the possible reactions of humic acid with actinides have been studied widely in recent years. The complex formation of Am (III) with humic acid is studied with solvent extraction technique in this paper. The experiments are performed in the pH range from 4.0 to 8.0 in 0.1 M NaClO4 solution at ambient temperature. Experimental results show that the complex formation constants of Am (III) with humic acid are varied with the variation of pH value in solution. 1:2 complex is obtained in the experiments and the complex formation constants determined at each pH are: lgβ1=6.56±0.05, lgβ2=10.77±0.31 at pH=4.0; lgβ1=7.94±0.11, lgβ2=11.80±0.21 at pH=5.0; lgβ1=10.74±0.28, lgβ2=12.88±0.49 at pH=6.0; lgβ1=12.85±0.30, lgβ2=14.80±0.62 at pH=7.0; lgβ1=14.88±0.48, lgβ2=15.65±0.69 at pH=8.0, respectively. The dependence of the complex of the complex formation constant on pH is: lgβ1=2.16(±0.98)pH-2.34(±1.03), lgβ2=1.28(±1.04)pH+5.52(±1.21), respectively. (author)

  10. Europium (III) and americium (III) stability constants with humic acid

    International Nuclear Information System (INIS)

    The stability constants for tracer concentrations of Eu(III) and Am(III) complexes with a humic acid extracted from a lake-bottom sediment were measured using a solvent extraction system. The organic extractant was di(2-ethylhexyl)-phosphoric acid in toluene while the humate aqueous phase had a constant ionic strength of 0.1 M (NaClO4). Aqueous humic acid concentrations were monitored by measuring uv-visible absorbances at approx.= 380 nm. The total carboxylate capacity of the humic acid was determined by direct potentiometric titration to be 3.86 +- 0.03 meq/g. The humic acid displayed typical characteristics of a polyelectrolyte - the apparent pKsub(a), as well as the calculated metal ion stability constants increased as the degree of ionization (α) increased. The binding data required a fit of two stability constants, β1 and β2, such that for Eu, log β1 = 8.86 α + 4.39, log β2 = 3.55 α + 11.06 while for Am, log β1 = 10.58 α + 3.84, log β2 = 5.32 α + 10.42. With hydroxide, carbonate, and humate as competing ligands, the humate complex associated with the β1 constant is calculated to be the dominant species for the trivalent actinides and lanthanides under conditions present in natural waters. (orig.)

  11. complex formation of americium (III) with humic acid

    International Nuclear Information System (INIS)

    The presence of humic substances in natural waters will modify the migration behavior of actinides in the geosphere due to the strong reaction properties of these ligands with actinides. Therefore, the possible reactions of humic acid with actinides have been studied widely in recent years. The complex formation of Am(III) with humic acid is studied with solvent extraction technique. The experiments are performed in the pH range from 4.0 to 8.0 in 0.1 mol/kg NaClO4 solution at ambient temperature. Experimental results show that the complex formation constants of Am(III) with humic acid are varied with the variation of pH value in solution. 1:2 complex is obtained in the experiments and the complex formation constants determined at each pH are: lgβ1 = 6.56 +- 0.05, lgβ2 = 10.77 +- 0.31 at pH 4.0. lgβ1 = 7.94 +- 0.11, lgβ2 = 11.80 +- 0.21 at pH = 5.0. lgβ1 = 10.74 +- 0.28, lgβ2 = 12.88 +- 0.49 at pH = 6.0. lgβ1 = 12.85 +- 0.30, lgβ2 = 14.80 +- 0.62 at pH = 7.0. lgβ1 = 14.88 +- 0.48, lgβ2 = 15.65 +- 0.69 at pH = 8.0, respectively. The dependence of the complex formation constant on pH is: lgβ1 = 2.16 (+-0.98)pH-2.34(+-0.93),lgβ2 1.28(+-1.04)pH+5.52(+-1.21), respectively

  12. Further Studies of Plutonium and Americium at Thule, Greenland

    DEFF Research Database (Denmark)

    Aarkrog, Asker; Dahlgaard, Henning; Nilsson, Karen Kristina;

    1984-01-01

    Eleven years after the accidental loss of nuclear weapons in 1968, the fourth scientific expedition to Thule occurred. The estimated inventory of 1 TBq 239,240Pu in the marine sediments was unchanged when compared with the estimate based on the 1974 data. Plutonium from the accident had moved...

  13. 'Americium(III)/trivalent lanthanides' separation using organothiophosphinic acids

    International Nuclear Information System (INIS)

    The present paper describes the extraction of neodymium and other lanthanides by saponified Cyanex 301 acid. The saponification of commercial Cyanex 301 acid favoured the extraction of macro concentrations of neodymium from sodium nitrate aqueous solutions (pHeq ∼ 4). The amount of lanthanide extracted in the organic phase always reached the third of the initial concentration of saponified Cyanex 301 acid, which assumed a cation exchange mechanism to occur during the extraction. No nitrate anion took part in the complex formation. This paper also compares the abilities of purified Cyanex 301, Cyanex 302 and Cyanex 272 acids to extract and separate 241Am(III) from 152Eu(III). Very high separation factors S.F.Am/Eu were observed in the case of purified Cyanex 301 acid. Finally some studies are presented herein using tri-n-butylphosphate (TBP) as a synergistic extractant with Cyanex 301 acid to separate actinides from trivalent lanthanide. (author)

  14. `Americium(III)/trivalent lanthanides` separation using organothiophosphinic acids

    Energy Technology Data Exchange (ETDEWEB)

    Hill, C.; Madic, C.; Baron, P. [CEA Marcoule, 30 - Bagnols-sur-Ceze (France); Ozawa, Masaki; Tanaka, Yasumasa

    1997-12-31

    The present paper describes the extraction of neodymium and other lanthanides by saponified Cyanex 301 acid. The saponification of commercial Cyanex 301 acid favoured the extraction of macro concentrations of neodymium from sodium nitrate aqueous solutions (pH{sub eq} {approx} 4). The amount of lanthanide extracted in the organic phase always reached the third of the initial concentration of saponified Cyanex 301 acid, which assumed a cation exchange mechanism to occur during the extraction. No nitrate anion took part in the complex formation. This paper also compares the abilities of purified Cyanex 301, Cyanex 302 and Cyanex 272 acids to extract and separate {sup 241}Am(III) from {sup 152}Eu(III). Very high separation factors S.F.{sub Am/Eu} were observed in the case of purified Cyanex 301 acid. Finally some studies are presented herein using tri-n-butylphosphate (TBP) as a synergistic extractant with Cyanex 301 acid to separate actinides from trivalent lanthanide. (author)

  15. Preparation of americium targets for nuclear chemistry experiments at DANCE

    International Nuclear Information System (INIS)

    Using 1 gram of 241Am from LANL stocks, the purification steps required to obtain a solution of 241Am from the original material are described. Part of the purified solution was submitted for purity analysis by mass spectrometry, radiochemistry and trace metals analysis. The impurities were expected to be 239Pu and 237Np. A second fraction of this material was used for electroplating three samples onto titanium disks that were suitable for insertion into an instrument package to be placed into the DANCE detector. The purification methods used, the electroplating setup and the solutions to various problems that were encountered in making these targets are discussed. The analytical results are discussed as well as the yields from the electrodeposition process. Comparison of these yields with those from similar experiments utilizing 235U and 243Am are also discussed. (author)

  16. Recovery of neptunium, plutonium, and americium from highly active waste

    International Nuclear Information System (INIS)

    Trialkylphosphine oxides (TRPO) (alkyl is 6c-C8) were chosen as the extractant for the recovery of Np, Pu, and Am from highly active waste (HAW) because of its extraction ability, excellent solvent behavior, high radiolytic stability, and low cost. Process chemistry based on 30 vol % TRPO-kerosene as solvent is presented. Extraction of Am in the presence of macro amounts of neodymium, adjustment of Np valence by electrolytic reduction, selective stripping of actinides from loaded organic phase, and loading capacity of the solvent are included. Process parameters of multistage countercurrent extraction and stripping and the results of experimental verification are given. From HAW with ∼1 M nitric acid concentration, recovery of actinides is higher than 99.9%. The actinides extracted can be stripped out separately into Am, Np-Pu, and U fractions. The behavior of nonactinide HAW constituents, including Tc, is discussed

  17. Property Data for Simulated Americium/Curium Glasses

    International Nuclear Information System (INIS)

    The authors studied the properties of mixed lanthanide-alumino-borosilicate glasses. Fifty-five glasses were designed to augment a previous, Phase I, study by systematically varying the composition of Ln2O3 and the concentrations of Ln2O3, SiO2, B2O3, Al2O3, and SrO in glass. These glasses were designed and fabricated at the Savannah River Technology Center and tested at the Pacific Northwest National Laboratory. The properties measured include the high-temperature viscosity (η) as a function of temperature (T) and the liquidus temperature (TL) of Phase II test glasses

  18. The vapour pressure of americium(III) chloride

    International Nuclear Information System (INIS)

    Based on the method described by Fischer, an ultramicro-size appratus was developed for static determination of the saturation vapour pressure of highly radioactive materials. The apparatus was tested with MgCl2, MnCl2, HoCl3 and ScF3. The vapour pressure curves of MgCl2 and MnCl2 were in good agreement with other publications and thus proved the efficiency of the apparatus in spite of its difficulties of handling. The values measured for HoCl3 and ScF3 differed from those of earlier publications. However, these deviations have been observed before and may be the result of the different measuring principles of static and dynamic methods. For AmCl3, the following vapour pressure equation was established: log psub(Torr)=-(11826/T)+10.7. The thermodynamic parameters of the evaporation process were calculated on this basis, and the values for AmBr3 and PnCl3 were determined by extrapolation. (orig.)

  19. Pressure-induced americium valence fluctuations revealed by electrical resistivity

    Czech Academy of Sciences Publication Activity Database

    Kolomiets, A. V.; Griveau, J.C.; Heathman, S.; Shick, Alexander; Wastin, F.; Faure, P.; Klosek, V.; Genestier, C.; Baclet, N.; Havela, L.

    2008-01-01

    Roč. 82, č. 5 (2008), 57007/1-57007/5. ISSN 0295-5075 R&D Projects: GA MŠk OC 144; GA ČR GA202/07/0644 Grant ostatní: EU(XE) RITA-CT-2006-026176 Institutional research plan: CEZ:AV0Z10100520 Keywords : electrical conductivity * strong electron interactions * electronic structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.203, year: 2008

  20. 1976 Hanford americium-exposure incident: accident description

    International Nuclear Information System (INIS)

    An accident is described, involving the explosion of an ion-exchange column containing about 100 g of 241Am. A chemical operator was injured in this accident, receiving acid burns and superficial cuts on the upper part of his body. From 1 to 5 curies of 241Am is estimated to have been deposited on the injured worker and on his clothing

  1. Investigation of the retention and distribution of americium-241 in the baboon and the enhanced removal of americium-241 from the body by diethylenetriaminepentaacetic acid (DTPA)

    International Nuclear Information System (INIS)

    Experiments were performed to study the metabolism and distribution of intravenously administered 241Am in the adult and juvenile baboon; in addition, decorporation therapy using Na3-CaDTPA was performed on selected baboons to assess the efficacy of this drug in removing systemic burdens of 241Am from this primate species. Determination of the kinetics of 241Am was accomplished principally by in vivo methodologies and by radiochemical analysis of 241Am activity of biological material. The use of Na3-CaDTPA as a therapeutic agent for the removal of 241Am from the body proved to be an effective form of treatment in the case of early administration. (U.S.)

  2. Preparation of EuSe nanoparticles from Eu(III) complex containing selenides

    International Nuclear Information System (INIS)

    The EuSe nanoparticles were prepared by the thermal reduction of Europium nitrate with new organic selenium compound, tetraphenylphosphonium diphenylphosphinediselenide (PPh4)(Se2P(C6H5)2), for the first time. EuSe nanoparticles were identified by the X-ray diffraction (XRD), the transmission electron microscope (TEM) and the energy dispersive X-ray spectroscopy (EDX) measurements. The average size of the EuSe nanoparticles was found to be 19 nm. The energy gap in EuSe nanoparticles of 19 nm was estimated by edge of absorption band, giving the energy gap of 1.86 eV

  3. Selenide isotope generator for the Galileo Mission: SIG/Galileo hermetic receptable test program final report

    International Nuclear Information System (INIS)

    The purpose of the receptacle test program was to test various types of hermetically sealed electrical receptacles and to select one model as the spaceflight hardware item for SIG/Galileo thermoelectric generators. The design goal of the program was to qualify a hermetic seal integrity of less than or equal to 1 x 10-9 std cc He/sec -atm at 4000F (2040C) and verify a reliability of 0.95 at a 50% confidence level for a flight mission in excess of 7 years

  4. Electronic structure of germanium selenide investigated using ultra-violet photo-electron spectroscopy

    International Nuclear Information System (INIS)

    The valence band electronic structure of GeSe single crystals has been investigated using angle resolved photoemission spectroscopy (ARPES) and x-ray photoelectron spectroscopy. The experimentally observed bands from ARPES, match qualitatively with our LDA-based band structure calculations along the Γ–Z, Γ–Y and Γ–T symmetry directions. The valence band maximum occurs nearly midway along the Γ–Z direction, at a binding energy of −0.5 eV, substantiating the indirect band gap of GeSe. Non-dispersive features associated with surface states and indirect transitions have been observed. The difference in hybridization of Se and Ge 4p orbitals leads to the variation of dispersion along the three symmetry directions. The predominance of the Se 4pz orbitals, evidenced from theoretical calculations, may be the cause for highly dispersive bands along the Γ–T direction. Detailed electronic structure analysis reveals the significance of the cation–anion 4p orbitals hybridization in the valence band dispersion of IV–VI semiconductors. This is the first comprehensive report of the electronic structure of a GeSe single crystal using ARPES in conjugation with theoretical band structure analysis. (paper)

  5. Semiconductor Surface Structure Determination via Low Energy Positron Diffraction: Cleavage Faces of Cadmium-Selenide

    Science.gov (United States)

    Horsky, Thomas Neil

    Low energy positron diffraction (LEPD) is used to determine the surface structure of the wurtzite CdSe(1010) and CdSe(1120) cleavage faces. Low energy electron diffraction (LEED) is also performed, utilizing a beam optical system which produces both a e^+ and e ^- beam with the same phase-space characteristics, i.e. 1 mm-deg. Both e^+ and e^- measurements were collected from the same sample surface of each cleavage face, removing systematic errors from the comparison. Dynamical calculations were performed for both the LEPD and LEED using the R-factor methodology of Duke et al. For the (1010) surface, the calculations and analyses were performed at Brandeis via link to the John Von Neumann Supercomputer Center at Princeton, NJ. For the (1120) surface, the LEPD calculations and analysis was performed by Battelle Pacific Northwest Laboratories, while the LEED calculations were performed by Princeton University. Resulting surface structures for CdSe(1010) are in accord with the proposed reconstruction model of Wang and Duke, indicating a bond-length-conserving rotation of the surface dimer. The best-fit values of the bond-rotation angle omega are 15^circ +/- 5^circ as determined by LEPD and omega = 21.5^ circ +/- 4^ circ as determined by LEED. These values are in agreement with the predicted value of omega = 17^circ. For CdSe(1120), the best-fit LEPD results indicate an omega of 27^circ +/- 7^circ while preliminary LEED results indicate an omega of 35^circ +/- 5^circ. Both values for this previously undetermined surface are also in agreement with the theoretically predicted value of omega = 32^circ . These results serve to confirm a universal model of reconstruction which describes the surface structures of both the zincblende and wurtzite compound semiconductor cleavage faces.

  6. Surfactant-thermal syntheses, structures, and magnetic properties of Mn-Ge-sulfides/selenides

    KAUST Repository

    Zhang, Guodong

    2014-10-06

    Although either surfactants or amines have been investigated to direct the crystal growth of metal chalcogenides, the synergic effect of organic amines and surfactants to control the crystal growth has not been explored. In this report, several organic bases (hydrazine monohydrate, ethylenediamine (en), 1,2-propanediamine (1,2-dap), and 1,3-propanediamine (1,3-dap)) have been employed as structure-directing agents (SDAs) to prepare four novel chalcogenides (Mn3Ge2S7(NH3)4 (1), [Mn(en)2(H2O)][Mn(en)2MnGe3Se9] (2), (1,2-dapH)2{[Mn(1,2-dap)2]Ge2Se7} (3), and (1,3-dapH)(puH)MnGeSe4(4) (pu = propyleneurea) under surfactant media (PEG-400). These as-prepared new crystalline materials provide diverse metal coordination geometries, including MnS3N tetrahedra, MnGe2Se7 trimer, and MnGe3Se10 T2 cluster. Compounds 1-3 have been fully characterized by single-crystal X-ray diffraction (XRD), powder XRD, UV-vis spectra, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Moreover, magnetic measurements for compound 1 showed an obvious antiferromagnetic transition at ∼9 K. Our research not only enriches the structural chemistry of the transitional-metal/14/16 chalcogenides but also allows us to better understand the synergic effect of organic amines and surfactants on the crystallization of metal chalcogenides.

  7. Electronic structure and thermoelectric properties of bismuth telluride and bismuth selenide

    International Nuclear Information System (INIS)

    The electronic structures of the two thermoelectric materials Bi2Te3 and Bi2Se3 are studied using density-functional theory with the spin - orbit interaction included. The electron states in the gap region and the chemical bonding can be described in terms of ppσ interaction between the atomic p orbitals within the 'quintuple' layer. For Bi2Se3, we find both the valence-band maximum as well as the conduction-band minimum, each with a nearly isotropic effective mass, to occur at the zone centre in agreement with experimental results. For Bi2Te3, we find that the six valleys for the valence-band maximum are located in the mirror planes of the Brillouin zone and they have a highly anisotropic effective mass, leading to an agreement between the de Haas-van Alphen data for the p-doped samples and the calculated Fermi surface. The calculated conduction band, however, has only two minima, instead of the six minima indicated from earlier experiments. The calculated Seebeck coefficients for both p-type and n-type materials are in agreement with the experiments. (author)

  8. Synthesis and characterization of Fe doped cadmium selenide thin films by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in [Thin Film Physics Laboratory, Department of Physics, Electronics and Photonics, Rajarshi Shahu Mahavidyalaya, Latur 413 512, Maharashtra (India)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer Simple and inexpensive method to dope trivalent Fe in CdSe thin films. Black-Right-Pointing-Pointer Fe doped CdSe thin films are highly photosensitive. Black-Right-Pointing-Pointer AFM analysis shows uniform deposition of film over the entire substrate surface. Black-Right-Pointing-Pointer The band gap energy decreases from 1.74 to 1.65 eV with Fe doping. Black-Right-Pointing-Pointer Film resistivity decreases to 6.76 Multiplication-Sign 10{sup 4} {Omega}-cm with Fe doping in CdSe thin films. - Abstract: Undoped and Fe doped CdSe thin films have been deposited onto the amorphous and fluorine doped tin oxide coated glass substrates by spray pyrolysis. The Fe doping concentration has been optimized by photoelectrochemical (PEC) characterization technique. The structural, surface morphological, compositional, optical and electrical properties of undoped and Fe doped CdSe thin films have been studied. X-ray diffraction study reveals that the as deposited CdSe films possess hexagonal crystal structure with preferential orientation along (1 0 0) plane. AFM analysis shows uniform deposition of the film over the entire substrate surface with minimum surface roughness of 7.90 nm. Direct allowed type of transition with band gap decreasing from 1.74 to 1.65 eV with Fe doping has been observed. The activation energy of the films has been found to be in the range of 0.14-0.19 eV at low temperature and 0.27-0.44 eV at high temperature. Semi-conducting behavior has been observed from resistivity measurements. The thermoelectric power measurements reveal that the films are of n type.

  9. Optical and structural properties of indium doped bismuth selenide thin films

    Science.gov (United States)

    Pavagadhi, Himanshu; Vyas, S. M.; Patel, Piyush; Patel, Vimal; Patel, Jaydev; Jani, M. P.

    2015-08-01

    In: Bi2Se3 crystals were grown by Bridgman method at a growth velocity of 0.5cm/h with temperature gradient of 650 C/cm in our laboratory. The thin films of In:Bi2se3 were grown on amorphous substrate (glass) at a room temperature under a pressure of 10-4Pa by thermal evaporation technique. Thin film were deposited at various thicknesses and optical absorption spectrum of such thin films, obtain in wave no. range 300 to 2600 cm-1. The optical energy gap calculated from this data were found to be inverse function of square of thickness, particularly for thickness about 1800 Å or less. This dependence is explained in terms of quantum size effect. For thicker films, the bandgap is found to be independent of film thickness. For the surface stud of the as grown thin film by using AFM, which shows continuous film with some step height and surface roughness found in terms of few nm and particle size varies with respect to thickness.

  10. Liquid precursor for deposition of indium selenide and method of preparing the same

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-22

    Liquid precursors containing indium and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and method of depositing a liquid precursor on a substrate are also disclosed.

  11. Synthesis and evaluation of diaryl sulfides and diaryl selenide compounds for antitubulin and cytotoxic activity

    Science.gov (United States)

    dos Santos, Edson dos A.; Hamel, Ernest; Bai, Ruoli; Burnett, James C.; Tozatti, Camila Santos Suniga; Bogo, Danielle; Perdomo, Renata T.; Antunes, Alexandra M. M.; Marques, M. Matilde; Matos, Maria de F. C.; de Lima, Dênis P.

    2013-01-01

    We have devised a procedure for the synthesis of analogs of combretastatin A-4 (CA-4) containing sulfur and selenium atoms as spacer groups between the aromatic rings. CA-4 is well known for its potent activity as an inhibitor of tubulin polymerization, and its prodrugs combretastatin A-4 phosphate (CA-4P) and combretastatin A-1 phosphate (CA-1P) are being investigated as antitumor agents that cause tumor vascular collapse in addition to their activity as cytotoxic compounds. Here we report the preparation of two sulfur analogs and one selenium analog of CA-4. All synthesized compounds, as well as several synthetic intermediates, were evaluated for inhibition of tubulin polymerization and for cytotoxic activity in human cancer cells. Compounds 3 and 4 were active at nM concentration against MCF-7 breast cancer cells. As inhibitors of tubulin polymerization, both 3 and 4 were more active than CA-4 itself. In addition, 4 was the most active of these agents against 786, HT-29 and PC-3 cancer cells. Molecular modeling binding studies are also reported for compounds 1, 3, 4 and CA-4 to tubulin within the colchicine site. PMID:23810282

  12. Photoelectrochemical salt water splitting using ternary silver-tin-selenide photoelectrodes

    Science.gov (United States)

    Cheng, Kong-Wei; Wu, Yu-Hsiang; Chiu, Ting-Hsuan

    2016-03-01

    Ternary AgSnSe2 and Ag8SnSe6 semiconductor photoelectrodes are prepared on various substrates via the selenization of thermally evaporation of silver-tin metal precursors. The structural, optical and electrical properties of ternary AgSnSe2 and Ag8SnSe6 samples are investigated as a function of the [Ag]/[Ag + Sn] molar ratio in the metal precursors. X-ray diffraction patterns of samples show that the phases of samples change from cubic AgSnSe2 to cubic Ag8SnSe6 phase at a selenization temperature of 410 °C when the molar ratio of [Ag]/[Ag + Sn] in silver-tin metal precursors increase from 0.51 to 0.68. The images obtained from a field-emission scanning electron microscopy show that the surface microstructures of samples change from plate-like microstructures with some pinholes to polygonal microstructures with increasing [Ag]/[Ag + Sn] molar ratios in samples. The energy bang gaps, carrier concentrations and mobilities of the samples are in the ranges of 0.86-1.19 eV, 1.27 × 1011-2.39 × 1012 cm-3 and 238-655 cm2 V-1 s-1, respectively. The highest photo-enhanced current densities of the samples in aqueous Na2S + K2SO3 and NaCl solutions are 3.34 and 0.61 mA cm-2 at an applied voltage of 0 and + 0.4 V vs. an Ag/AgCl electrode under 100 mW cm-2 light illumination from a Xe lamp source, respectively.

  13. Synthesis, structure and electrical properties of a new tin vanadium selenide

    International Nuclear Information System (INIS)

    The turbostratically disordered misfit layer compound (SnSe)1.15VSe2 was synthesized and structurally characterized. Electrical transport measurements suggest this compound undergoes a charge or spin density wave (CDW or SDW) transition, which has not been observed in previous misfit layer compounds. The (SnSe)1.15VSe2 compound, created through the modulated elemental reactants technique, contains highly oriented intergrowths of SnSe bilayers and VSe2 structured Se–V–Se trilayers with abrupt interfaces between them perpendicular to the c-axis. X-ray diffraction data and transmission electron microscope images show that each constituent has in-plane crystallinity but that there is a random rotational disorder between the constituent layers. Temperature-dependent electrical resistivity data and Hall measurements are consistent with (SnSe)1.15VSe2 being a metal, however an abrupt increase in the resistivity occurs between 30 and 100 K. The carrier concentration decreases by approximately 1 carrier per vanadium atom during this temperature interval. - Graphical abstract: Turbostratically disordered (SnSe)1.15VSe2. - Highlights: • New compound (SnSe)1.15VSe2. • Turbostratic disorder. • Charge density wave at 100 K

  14. Physical ageing in the above-bandgap photoexposured glassy arsenic selenides

    Energy Technology Data Exchange (ETDEWEB)

    Kozdras, A [Faculty of Physics of Opole University of Technology, 75, Ozimska str., Opole, PL-45370 (Poland); Golovchak, R [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-79031 (Ukraine); Shpotyuk, O [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-79031 (Ukraine)

    2007-08-15

    Physical ageing induced by above-bandgap light illumination is studied in glassy As-Se using differential scanning calorimetry. It is shown that measurable effect like to known short-term physical ageing is observed only in Se-rich glasses. The kinetics of this effect is compared with that caused by natural storage in a dark.

  15. Step-wise kinetics of natural physical ageing in arsenic selenide glasses

    International Nuclear Information System (INIS)

    The long-term kinetics of physical ageing at ambient temperature is studied in Se-rich As-Se glasses using the conventional differential scanning calorimetry technique. It is analysed through the changes in the structural relaxation parameters occurring during the glass-to-supercooled liquid transition in the heating mode. Along with the time dependences of the glass transition temperature (Tg) and partial area (A) under the endothermic relaxation peak, the enthalpy losses (ΔH) and calculated fictive temperature (TF) are analysed as key parameters, characterizing the kinetics of physical ageing. The latter is shown to have step-wise character, revealing some kinds of subsequent plateaus and steep regions. A phenomenological description of physical ageing in the investigated glasses is proposed on the basis of an alignment-shrinkage mechanism and first-order kinetic equations.

  16. Cluster modeling of quasi-adaptive phases in vitreous germanium selenides

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, Oleh; Golovchak, Roman [Lviv Institute of Materials of SRC, Lviv 79031 (Ukraine); Institute of Physics, Jan Dlugosz University, Czestochowa 42201 (Poland); Boyko, Vitaliy [Lviv Polytechnic National University, Lviv 79013 (Ukraine); Kozyukhin, Sergei [Institute of General and Inorganic Chemistry of RAS, Leninsky Pr. 31, Moscow 199991 (Russian Federation)

    2010-04-15

    The developed cluster modeling approach based on ab-initio calculations with RHF/6-311G{sup *} basis set testifies absence of intermediate optimally-constrained phase in binary Ge{sub x} Se{sub 100-x} system within 20 {<=} x < 26 domain. It is shown, that character ''outrigger raft'' carcass is conserved for all glass compositions within expected reversibility window. Thus, the structure of binary Ge{sub x} Se{sub 100-x} glasses can be described in terms of ''chains crossing'' model in case of x < 12, mixed ''chains crossing'' and ''outrigger raft'' models in case of 12{<=}x< 20 and modified ''outrigger raft'' model in case of x {>=} 20. The expected reversibility window in binary Ge{sub x} Se{sub 100-x} glasses is shown to be only quasi-adaptive phase, based on ''outrigger raft'' structural motive with two edge- and four corner-sharing tetrahedra interconnected by optimally-constrained Ge-Se-Se-Ge bridges with extra Se atoms in ring-like configurations replaced Se-Se dimers. The results of quantum mechanics modeling are confirmed well by high-resolution X-ray photoelectron spectroscopy measurements in this system. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Study of Ga incorporation in glassy arsenic selenides by high-resolution XPS and EXAFS

    Energy Technology Data Exchange (ETDEWEB)

    Golovchak, R., E-mail: holovchakr@apsu.edu [Department of Physics and Astronomy, Austin Peay State University, Clarksville, Tennessee 37044 (United States); Shpotyuk, Ya. [Equipe Verres et Céramiques UMR-CNRS 6226, Université de Rennes 1, 35042 Rennes Cedex (France); Scientific Research Company “Carat”, 202, Stryjska Str., 79031 Lviv (Ukraine); Nazabal, V.; Boussard-Pledel, C.; Bureau, B. [Equipe Verres et Céramiques UMR-CNRS 6226, Université de Rennes 1, 35042 Rennes Cedex (France); Cebulski, J. [Center for Microelectronics and Nanotechnology, University of Rzeszow, 1, Pigonia Str., 35-310 Rzeszow (Poland); Jain, H. [Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, Pennsylvania 18015-3195 (United States)

    2015-05-14

    Effect of Ga addition on the structure of vitreous As{sub 2}Se{sub 3} is studied using high-resolution X-ray photoelectron spectroscopy and extended X-ray absorption fine structure techniques. The “8-N” rule is shown to be violated for Ga atoms and, possibly, for certain number of As atoms. On the contrary, Se keeps its 2-fold coordination according to “8-N” rule in the amorphous phase throughout all the compositions. Crystalline inclusions appear in the amorphous structure of the investigated glasses at Ga concentrations greater than 3 at. %. These inclusions are presumably associated with Ga{sub 2}Se{sub 3} crystallites and transition phases/defects formed at the boundaries of these crystallites and host amorphous matrix. The existence of Ga–As and Se–Se bonds in the samples with higher Ga content is supported by present studies.

  18. Step-wise kinetics of natural physical ageing in arsenic selenide glasses.

    Science.gov (United States)

    Golovchak, R; Kozdras, A; Balitska, V; Shpotyuk, O

    2012-12-19

    The long-term kinetics of physical ageing at ambient temperature is studied in Se-rich As-Se glasses using the conventional differential scanning calorimetry technique. It is analysed through the changes in the structural relaxation parameters occurring during the glass-to-supercooled liquid transition in the heating mode. Along with the time dependences of the glass transition temperature (T(g)) and partial area (A) under the endothermic relaxation peak, the enthalpy losses (ΔH) and calculated fictive temperature (T(F)) are analysed as key parameters, characterizing the kinetics of physical ageing. The latter is shown to have step-wise character, revealing some kinds of subsequent plateaus and steep regions. A phenomenological description of physical ageing in the investigated glasses is proposed on the basis of an alignment-shrinkage mechanism and first-order kinetic equations. PMID:23174805

  19. Study of Ga incorporation in glassy arsenic selenides by high-resolution XPS and EXAFS.

    Science.gov (United States)

    Golovchak, R; Shpotyuk, Ya; Nazabal, V; Boussard-Pledel, C; Bureau, B; Cebulski, J; Jain, H

    2015-05-14

    Effect of Ga addition on the structure of vitreous As2Se3 is studied using high-resolution X-ray photoelectron spectroscopy and extended X-ray absorption fine structure techniques. The "8-N" rule is shown to be violated for Ga atoms and, possibly, for certain number of As atoms. On the contrary, Se keeps its 2-fold coordination according to "8-N" rule in the amorphous phase throughout all the compositions. Crystalline inclusions appear in the amorphous structure of the investigated glasses at Ga concentrations greater than 3 at. %. These inclusions are presumably associated with Ga2Se3 crystallites and transition phases/defects formed at the boundaries of these crystallites and host amorphous matrix. The existence of Ga-As and Se-Se bonds in the samples with higher Ga content is supported by present studies. PMID:25978894

  20. Study of Ga incorporation in glassy arsenic selenides by high-resolution XPS and EXAFS

    International Nuclear Information System (INIS)

    Effect of Ga addition on the structure of vitreous As2Se3 is studied using high-resolution X-ray photoelectron spectroscopy and extended X-ray absorption fine structure techniques. The “8-N” rule is shown to be violated for Ga atoms and, possibly, for certain number of As atoms. On the contrary, Se keeps its 2-fold coordination according to “8-N” rule in the amorphous phase throughout all the compositions. Crystalline inclusions appear in the amorphous structure of the investigated glasses at Ga concentrations greater than 3 at. %. These inclusions are presumably associated with Ga2Se3 crystallites and transition phases/defects formed at the boundaries of these crystallites and host amorphous matrix. The existence of Ga–As and Se–Se bonds in the samples with higher Ga content is supported by present studies