Theoretical investigation of electronic structure, electric field gradients, and photoemission of PuCoGa.sub.5./sub. and PuRhGa.sub.5./sub. superconductors

Czech Academy of Sciences Publication Activity Database

Shick, Alexander; Rusz, Ján; Kolorenč, Jindřich; Oppeneer, P.M.; Havela, L.

2011-01-01

Roč. 83, č. 15 (2011), "155105-1"-"155105-7" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP204/10/0330; GA AV ČR IAA100100912 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetism * superconductivity * PuCoGa 5 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

Neutron diffraction study of δ-alloy Pu{sup 242}–Ga aging

Energy Technology Data Exchange (ETDEWEB)

Somenkov, V.A. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Blanter, M.S., E-mail: mike.blanter@gmail.com [Moscow State University of Instrumental Engineering and Information Science, Moscow (Russian Federation); Glazkov, V.P. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Laushkin, A.V.; Orlov, V.K. [JSC VNIINM n.a. A.A. Bochvar, Moscow (Russian Federation)

2014-09-15

In this paper, we report on a continuing neutron diffraction study of the mean-square atom displacements occurring during the long-term self-irradiation of a Pu–Ga alloy. The measurements were performed at room temperature using the sample based on the isotope Pu{sup 242} with low neutron absorption cross-section to which the short-lived isotope Pu{sup 238} (1.4 wt.%) was added to accelerate self-irradiation. We obtain the maximum self-irradiation equivalent time of 35.5 years, 12 years longer than in our previous papers. In the entire range of self-irradiation time a single fcc phase is preserved. It was found that after the two stages of change in the mean-square displacements we observed earlier (rapid growth up to ∼5–6 equivalent years and a slow decline in the range of ∼6–25 years), comes a stage of stabilization (after ∼25 years). The stabilization can be explained by the emergence of a balance between the formation of point defects and their absorption by helium bubbles and dislocation loops which accumulated over time.

Enhancement of relaxation rates in the normal state of superconductor PuRhGa5:NQR relaxation study

International Nuclear Information System (INIS)

Sakai, H.; Kambe, S.; Tokunaga, Y.; Fujimoto, T.; Walstedt, R.E.; Yasuoka, H.; Aoki, D.; Homma, Y.; Yamamoto, E.; Nakamura, A.; Shiokawa, Y.; Nakajima, K.; Arai, Y.; Matsuda, T.D.; Haga, Y.; Onuki, Y.

2007-01-01

The spin-lattice relaxation rates (1/T 1 ) have been measured under zero field using nuclear quadrupole resonance (NQR) lines in superconductor PuRhGa 5 and Pauli-paramagnet LuCoGa 5 . In the reference LuCoGa 5 with fully-occupied 4f shell, the 1/T 1 shows the constant behavior of (T 1 T) -1 =0.495+/-0.002(sK) -1 . On the other hand, in PuRhGa 5 , 1/T 1 is much larger than in LuCoGa 5 and the 1/T 1 ∝T behavior below ∼30K is seen, where its (T 1 T) -1 value is 3.27+/-0.005(sK) -1 . These results suggest a development of coherent Fermi liquid state incorporated with 5f electrons below ∼30K in PuRhGa 5

Lattice relaxation and the stability of plutonium-based alloys and intermetallics

International Nuclear Information System (INIS)

Becker, J.D.; Cox, L.; Wills, J.M.; Cooper, B.R.

1996-01-01

The topic of this study is the electronic structure of the compounds Pu 3 X [X = In, Ga, Al, or Tl], reported to have room temperature L1 2 structures. The measured Pu-Pu bond length in δ-phase Pu is 3.28 Angstrom. The Pu-Pu bond lengths in Pu 3 Ga and Pu 3 Al are 3.18 Angstrom. The similarity in bonding in Pu 3 Ga and Pu 3 Al is especially notable as the equilibrium atomic volume in Ga is 18% higher than that of Al. Likewise, in Pu 3 In and Pu 3 Tl the bond lengths are 3.33 Angstrom and 3.32 Angstrom, respectively, although the atomic volumes of In and Tl differ by 10%. The electronic mechanism by which the 8 stabilizers Al and Ga contract the Pu-Pu bonds and whereby In and Tl stretch them may relate the stability of pure Pu to that of the Pu 3 X compounds. For example, does the addition of Ga or Al shorten the bond length enough to make the close-packed Ll 2 structure more stable than does the addition of In or Tl? The incipient localization of the f electrons and the stabilization of open structures may be indicated through LDA total energies and densities of states

Characterization and technology of AlGaAs/GaAs phototransistor with double delta-doped base

International Nuclear Information System (INIS)

Radziewicz, D.; Sciana, B.; Pucicki, D.; Zborowska-Lindert, I.; Kovac, J.; Skriniarova, J.; Vincze, A.

2011-01-01

This work describes the fabrication and measurements of n-p-n AlGaAs/GaAs heterojunction phototransistor with double Zn-delta-doped 50 nm - thick GaAs base region. Parameters of the particular transistor epilayers were optimized by computer simulations using Silvaco Atlas program. (authors)

Above room-temperature ferromagnetism of Mn delta-doped GaN nanorods

International Nuclear Information System (INIS)

Lin, Y. T.; Wadekar, P. V.; Kao, H. S.; Chen, T. H.; Chen, Q. Y.; Tu, L. W.; Huang, H. C.; Ho, N. J.

2014-01-01

One-dimensional nitride based diluted magnetic semiconductors were grown by plasma-assisted molecular beam epitaxy. Delta-doping technique was adopted to dope GaN nanorods with Mn. The structural and magnetic properties were investigated. The GaMnN nanorods with a single crystalline structure and with Ga sites substituted by Mn atoms were verified by high-resolution x-ray diffraction and Raman scattering, respectively. Secondary phases were not observed by high-resolution x-ray diffraction and high-resolution transmission electron microscopy. In addition, the magnetic hysteresis curves show that the Mn delta-doped GaN nanorods are ferromagnetic above room temperature. The magnetization with magnetic field perpendicular to GaN c-axis saturates easier than the one with field parallel to GaN c-axis

Spin-polarized electron tunneling across a Si delta-doped GaMnAs/n-GaAs interface

DEFF Research Database (Denmark)

Andresen, S.E.; Sørensen, B.S.; Lindelof, P.E.

2003-01-01

Spin-polarized electron coupling across a Si delta-doped GaMnAs/n-GaAs interface was investigated. The injection of spin-polarized electrons was detected as circular polarized emission from a GaInAs/GaAs quantum well light emitting diode. The angular momentum selection rules were simplified...

{sup 137}Cs, {sup 239+240}Pu concentrations and the {sup 240}Pu/{sup 239}Pu atom ratio in a sediment core from the sub-aqueous delta of Yangtze River estuary

Energy Technology Data Exchange (ETDEWEB)

Pan, S.M., E-mail: span@nju.edu.cn [Key Lab of Ministry of Education of Coast and Island Development, Nanjing University, Nanjing 210093 (China); Tims, S.G. [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Liu, X.Y. [Key Lab of Ministry of Education of Coast and Island Development, Nanjing University, Nanjing 210093 (China); Fifield, L.K. [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

2011-10-15

A sediment core collected from the sub-aqueous delta of the Yangtze River estuary was subjected to analyses of {sup 137}Cs and plutonium (Pu) isotopes. The {sup 137}Cs was measured using {gamma}-spectrometry at the laboratories at the Nanjing University and Pu isotopes were determined with Accelerator Mass Spectrometry (AMS), measurements made at the Australian National University. The results show considerable structure in the depth concentration profiles of the {sup 137}Cs and {sup 239+240}Pu. The shape of the vertical {sup 137}Cs distribution in the sediment core was similar to that of the Pu. The maximum {sup 137}Cs and {sup 239+240}Pu concentrations were 16.21 {+-} 0.95 mBq/g and 0.716 {+-} 0.030 mBq/g, respectively, and appear at same depth. The average {sup 240}Pu/{sup 239}Pu atom ratio was 0.238 {+-} 0.007 in the sediment core, slightly higher than the average global fallout value. The changes in the {sup 240}Pu/{sup 239}Pu atom ratios in the sediment core indicate the presence of at least two different Pu sources, i.e., global fallout and another source, most likely close-in fallout from the Pacific Proving Grounds (PPG) in the Marshall Islands, and suggest the possibility that Pu isotopes are useful as a geochronological tool for coastal sediment studies. The {sup 137}Cs and {sup 239+240}Pu inventories were estimated to be 7100 {+-} 1200 Bq/m{sup 2} and 407 {+-} 27 Bq/m{sup 2}, respectively. Approximately 40% of the {sup 239+240}Pu inventory originated from the PPG close-in fallout and about 50% has derived from land-origin global fallout transported to the estuary by the river. This study confirms that AMS is a useful tool to measure {sup 240}Pu/{sup 239}Pu atom ratio and can provide valuable information on sedimentary processes in the coastal environment.

Photoreflectance study of InAs ultrathin layer embedded in Si-delta-doped GaAs/AlGaAs quantum wells

Energy Technology Data Exchange (ETDEWEB)

Dhifallah, I., E-mail: ines.dhifallah@gmail.co [Laboratoire de Photovoltaique, des Semiconducteurs et des Nanostructures, Centre de Recherche et des Technologies de l' energie, BP 95 Hammam-Lif 2050 (Tunisia); Daoudi, M.; Bardaoui, A. [Laboratoire de Photovoltaique, des Semiconducteurs et des Nanostructures, Centre de Recherche et des Technologies de l' energie, BP 95 Hammam-Lif 2050 (Tunisia); Eljani, B. [Unite de recherche sur les Hetero-Epitaxie et Applications, Faculte des Sciences de Monastir (Tunisia); Ouerghi, A. [Laboratoire de Photonique et de Nanostructures, CNRS Route de Nozay 91 46a0, Marcoussis (France); Chtourou, R. [Laboratoire de Photovoltaique, des Semiconducteurs et des Nanostructures, Centre de Recherche et des Technologies de l' energie, BP 95 Hammam-Lif 2050 (Tunisia)

2011-05-15

Photoreflectance and photoluminescence studies were performed to characterize InAs ultrathin layer embedded in Si-delta-doped GaAs/AlGaAs high electron mobility transistors. These structures were grown by Molecular Beam Epitaxy on (1 0 0) oriented GaAs substrates with different silicon-delta-doped layer densities. Interband energy transitions in the InAs ultrathin layer quantum well were observed below the GaAs band gap in the photoreflectance spectra, and assigned to electron-heavy-hole (E{sub e-hh}) and electron-light-hole (E{sub e-lh}) fundamental transitions. These transitions were shifted to lower energy with increasing silicon-{delta}-doping density. This effect is in good agreement with our theoretical results based on a self-consistent solution of the coupled Schroedinger and Poisson equations and was explained by increased escape of photogenerated carriers and enhanced Quantum Confined Stark Effect in the Si-delta-doped InAs/GaAs QW. In the photoreflectance spectra, not only the channel well interband energy transitions were observed, but also features associated with the GaAs and AlGaAs bulk layers located at about 1.427 and 1.8 eV, respectively. By analyzing the Franz-Keldysh Oscillations observed in the spectral characteristics of Si-{delta}-doped samples, we have determined the internal electric field introduced by ionized Si-{delta}-doped centers. We have observed an increase in the electric field in the InAs ultrathin layer with increasing silicon content. The results are explained in terms of doping dependent ionized impurities densities and surface charges. - Research highlights: {yields} Studying HEMTs structures with different silicon doping content. {yields} An increase of the electric field in the InAs layer with increasing Si content. {yields} The interband energy transitions in the HEMTs structures have been obtained from PR. {yields} Experimental and theoretical values of transitions energies were in good agreement.

Probing Magnetism in the Vortex Phase of PuCoGa_{5} by X-Ray Magnetic Circular Dichroism.

Science.gov (United States)

Magnani, N; Eloirdi, R; Wilhelm, F; Colineau, E; Griveau, J-C; Shick, A B; Lander, G H; Rogalev, A; Caciuffo, R

2017-10-13

We measure x-ray magnetic circular dichroism (XMCD) spectra at the Pu M_{4,5} absorption edges from a newly prepared high-quality single crystal of the heavy-fermion superconductor ^{242}PuCoGa_{5}, exhibiting a critical temperature T_{c}=18.7  K. The experiment probes the vortex phase below T_{c} and shows that an external magnetic field induces a Pu 5f magnetic moment at 2 K equal to the temperature-independent moment measured in the normal phase up to 300 K by a superconducting quantum interference device. This observation is in agreement with theoretical models claiming that the Pu atoms in PuCoGa_{5} have a nonmagnetic singlet ground state resulting from the hybridization of the conduction electrons with the intermediate-valence 5f electronic shell. Unexpectedly, XMCD spectra show that the orbital component of the 5f magnetic moment increases significantly between 30 and 2 K; the antiparallel spin component increases as well, leaving the total moment practically constant. We suggest that this indicates a low-temperature breakdown of the complete Kondo-like screening of the local 5f moment.

Overview of advanced technologies for stabilization of 238Pu-contaminated waste

International Nuclear Information System (INIS)

Ramsey, K.B.; Foltyn, E.M.; Heslop, J.M.

1998-02-01

This paper presents an overview of potential technologies for stabilization of 238 Pu-contaminated waste. Los Alamos National Laboratory (LANL) has processed 238 PuO 2 fuel into heat sources for space and terrestrial uses for the past several decades. The 88-year half-life of 238 Pu and thermal power of approximately 0.6 watts/gram make this isotope ideal for missions requiring many years of dependable service in inaccessible locations. However, the same characteristic which makes 238 Pu attractive for heat source applications, the high Curie content (17 Ci/gram versus 0.06 Ci/gram for 239 Pu ), makes disposal of 238 Pu-contaminated waste difficult. Specifically, the thermal load limit on drums destined for transport to the Waste Isolation Pilot Plant (WIPP), 0.23 gram per drum for combustible waste, is impossible to meet for nearly all 238 Pu-contaminated glovebox waste. Use of advanced waste treatment technologies including Molten Salt Oxidation (MSO) and aqueous chemical separation will eliminate the combustible matrix from 238 Pu-contaminated waste and recover kilogram quantities of 238 PuO 2 from the waste stream. A conceptual design of these advanced waste treatment technologies will be presented

Strong-coupling d-wave superconductivity in PuCoGa.sub.5./sub. probed by point-contact spectroscopy

Czech Academy of Sciences Publication Activity Database

Daghero, D.; Tortello, M.; Ummarino, G.A.; Griveau, J.C.; Colineau, E.; Eloirdi, R.; Shick, Alexander; Kolorenč, Jindřich; Lichtenstein, A.I.; Caciuffo, R.

2012-01-01

Roč. 3, Apr (2012), "786-1"-"786-8" ISSN 2041-1723 R&D Projects: GA ČR(CZ) GAP204/10/0330; GA AV ČR IAA100100912 Institutional research plan: CEZ:AV0Z10100520 Keywords : superconductivity * PuCoGa 5 * magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 10.015, year: 2012 http://www.nature.com/ncomms/journal/v3/n4/full/ncomms1785.html

Comparison of U-Pu-Mo, U-Pu-Nb, U-Pu-Ti and U-Pu-Zr alloys

International Nuclear Information System (INIS)

Boucher, R.; Barthelemy, P.

1964-01-01

The data concerning the U-Pu, U-Pu-Mo and U-Pu-Nb are recalled. The results obtained with U-Pu-Ti and U-Pu-Zr alloys containing 15-20 per cent Pu and 10 wt. per cent ternary element are reported. The transformation temperatures, the expansion coefficients, the nature of phases, the thermal cycling behaviour have been determined. A list of the principal properties of these different alloys is presented and the possibilities of their use as fast reactor's fuel element are considered. The U-Pu-Ti alloys seem to be quite promising: easiness of fabrication, large thermal stability, excellent behaviour in air, small quantity of zeta phase, temperature of solidus superior to 1100 deg. C. (authors) [fr

Microstructural analysis of the {delta} to {alpha}' phase transformation in plutonium alloys using X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Platteau, C; Ravat, B; Texier, G; Oudot, B; Delaunay, F, E-mail: brice.ravat@cea.fr [CEA Valduc 21120 Is sur Tille (France)

2010-03-15

The partial martensitic {delta}{yields}{alpha}' transformation in plutonium alloys is sensitive to chemical composition, sample thermal history, as well as crystalline defects. The present work investigates the {delta}-Pu phase microstructure before and after the martensitic transformation {delta}{yields}{delta}+{alpha}'. More precisely, microstructural modifications of the host {delta}-phase, resulting from the stress induced by a cell volume difference of 19% between the {delta} and {alpha}'-phases, were analysed. Microstructural information about crystallite size and microstrain of a highly homogenized Pu-Ga alloy was extracted from x-ray diffraction patterns using a three dimension crystallite size and microstrain model. This is available in Rietveld refinement software and consists in anisotropic broadening analysis of diffraction peaks. Crystallite size doesn't significantly change with the phase transformation contrary to microstrain that is multiplied, on average, by five. Furthermore, internal normal and shear microstress are multiplied, respectively, by 2 and 13 when {alpha}'-phase appears. Last, dislocation densities, calculated from crystallite size and microstrain, are compared to TEM results available in the literature.

Self-irradiation damage to the local structure of plutonium and plutonium intermetallics

Energy Technology Data Exchange (ETDEWEB)

Booth, C. H.; Jiang Yu; Medling, S. A. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Wang, D. L. [Nuclear Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Costello, A. L.; Schwartz, D. S.; Mitchell, J. N.; Tobash, P. H. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bauer, E. D. [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); McCall, S. K.; Wall, M. A.; Allen, P. G. [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2013-03-07

The effect of self-irradiation damage on the local structure of {delta}-Pu, PuAl{sub 2}, PuGa{sub 3}, and other Pu intermetallics has been determined for samples stored at room temperature using the extended x-ray absorption fine-structure (EXAFS) technique. These measurements indicate that the intermetallic samples damage at a similar rate as indicated in previous studies of PuCoGa{sub 5}. In contrast, {delta}-Pu data indicate a much slower damage accumulation rate. To explore the effect of storage temperature and possible room temperature annealing effects, we also collected EXAFS data on a {delta}-Pu sample that was held at less than 32 K for a two month period. This sample damaged much more quickly. In addition, the measurable damage was annealed out at above only 135 K. Data from samples of {delta}-Pu with different Ga concentrations and results on all samples collected from different absorption edges are also reported. These results are discussed in terms of the vibrational properties of the materials and the role of Ga in {delta}-Pu as a network former.

Determination of the stability constant for the Pu(IV)-dinitrato complex using UV-VIS spectrophotometry

International Nuclear Information System (INIS)

Smith, C.A.; Veirs, D.K.

1994-01-01

Efficiency of the anion exchange process for the separation of plutonium is critically dependent upon the formation of the specific Pu(IV) nitrate complexes. Previous work is ambiguous as to the identification of the principal Pu(IV)-nitrate species present in nitric acid solutions. In this work, the authors study the nitrate complexes within the inner coordination sphere of Pu(IV) using absorption spectroscopy (nitrates in the outer coordination sphere probably do not affect the Pu(IV) absorption spectrum). The authors show that the Pu(IV)-aquo and -dinitrato species are associated with major peaks in the absorption spectrum at 469 and 476 nm, respectively. Absorption data from solutions where the nitrate concentration is varied at constant ionic strength are used to calculate stability constants for the dinitrato species, β 2 . Calculation of the stability constant at zero ionic strength and ion interaction coefficients are discussed

Influence of the goethite (α-FeOOH) surface on the stability of distorted PuO{sub 2} and PuO{sub 2-x} phases

Energy Technology Data Exchange (ETDEWEB)

Taylor, Sandra D.; Becker, Udo [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Earth and Environmental Sciences; Powell, Brian A. [Clemson Univ., Anderson, SC (United States). Environmental Engineering and Earth Science Dept.

2016-07-01

Experiments by [Powell, B. A., Dai, Z. R., Zavarin, M., Zhao, P. H., Kersting, A. B.: Stabilization of plutonium nano-colloids by epitaxial distortion on mineral surfaces. Environ. Sci. Technol. 45, 2698 (2011).] deduced the heteroepitaxial growth of a bcc Pu{sub 4}O{sub 7} phase when sorbed onto goethite from d-spacing measurements obtained from selected-area electron diffraction (SAED) patterns. The structural and/or chemical modification of Pu(IV) oxide (PO) nanocolloids upon sorption to goethite, in turn, affects colloidal-transport of Pu in the subsurface. In this study, molecular simulations were applied to investigate mechanisms affecting the formation of non-fcc PO phases and to understand the influence of goethite in stabilizing the non-fcc PO phase. Analyses of the structure, chemistry, and formation energetics for several bulk PuO{sub 2} and PuO{sub 2-x} phases, using ab initio methods, show that the formation of a non-fcc PO can occur from the lattice distortion (LD) of fcc PuO{sub 2} upon sorption and formation of a PO-goethite interface. To strain and non-uniformly distort the PuO{sub 2} lattice to match that of the goethite substrate at ambient conditions would require 88 kJ/mol Pu{sub 4}O{sub 8}. The formation of a hypostoichiometric PuO{sub 2-x} phase, such as the experimentally-deduced bcc, Ia anti 3 Pu{sub 4}O{sub 7} phase, requires more O-poor conditions and/or high energetic inputs (> +365 kJ/mol Pu{sub 4}O{sub 7} at O-rich conditions). Empirical methods were also applied to study the effect of lattice distortion on sorption energetics and adsorbate particle growth using simple heterointerfaces between cubic salts, where KCl clusters (notated as KCl{sub LD}) of varying size and lattice mismatch (LM) were sorbed to a NaCl cluster. When the lattice of a KCl{sub LD} cluster has <15% LM with that of a NaCl substrate, the sorption of KCl{sub LD} onto NaCl is exothermic (<-80 kJ/mol) and the KCl{sub LD} cluster can reach sizes of ∝2-5 nm on the Na

Photoreflectance study of InAs ultrathin layer embedded in Si-delta-doped GaAs/AlGaAs quantum wells

International Nuclear Information System (INIS)

Dhifallah, I.; Daoudi, M.; Bardaoui, A.; Eljani, B.; Ouerghi, A.; Chtourou, R.

2011-01-01

Photoreflectance and photoluminescence studies were performed to characterize InAs ultrathin layer embedded in Si-delta-doped GaAs/AlGaAs high electron mobility transistors. These structures were grown by Molecular Beam Epitaxy on (1 0 0) oriented GaAs substrates with different silicon-delta-doped layer densities. Interband energy transitions in the InAs ultrathin layer quantum well were observed below the GaAs band gap in the photoreflectance spectra, and assigned to electron-heavy-hole (E e-hh ) and electron-light-hole (E e-lh ) fundamental transitions. These transitions were shifted to lower energy with increasing silicon-δ-doping density. This effect is in good agreement with our theoretical results based on a self-consistent solution of the coupled Schroedinger and Poisson equations and was explained by increased escape of photogenerated carriers and enhanced Quantum Confined Stark Effect in the Si-delta-doped InAs/GaAs QW. In the photoreflectance spectra, not only the channel well interband energy transitions were observed, but also features associated with the GaAs and AlGaAs bulk layers located at about 1.427 and 1.8 eV, respectively. By analyzing the Franz-Keldysh Oscillations observed in the spectral characteristics of Si-δ-doped samples, we have determined the internal electric field introduced by ionized Si-δ-doped centers. We have observed an increase in the electric field in the InAs ultrathin layer with increasing silicon content. The results are explained in terms of doping dependent ionized impurities densities and surface charges. - Research highlights: → Studying HEMTs structures with different silicon doping content. → An increase of the electric field in the InAs layer with increasing Si content. → The interband energy transitions in the HEMTs structures have been obtained from PR. → Experimental and theoretical values of transitions energies were in good agreement.

Comparison of U-Pu-Mo, U-Pu-Nb, U-Pu-Ti and U-Pu-Zr alloys; Comparaison des alliages U-Pu-Mo, U-Pu-Nb, U-Pu-Ti, U-Pu-Zr

Energy Technology Data Exchange (ETDEWEB)

Boucher, R; Barthelemy, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1964-07-01

The data concerning the U-Pu, U-Pu-Mo and U-Pu-Nb are recalled. The results obtained with U-Pu-Ti and U-Pu-Zr alloys containing 15-20 per cent Pu and 10 wt. per cent ternary element are reported. The transformation temperatures, the expansion coefficients, the nature of phases, the thermal cycling behaviour have been determined. A list of the principal properties of these different alloys is presented and the possibilities of their use as fast reactor's fuel element are considered. The U-Pu-Ti alloys seem to be quite promising: easiness of fabrication, large thermal stability, excellent behaviour in air, small quantity of zeta phase, temperature of solidus superior to 1100 deg. C. (authors) [French] On rappelle brievement les connaissances acquises sur les alliages U-Pu, U-Pu-Mo et U-Pu-Nb. On presente les resultats obtenus avec les alliages U-Pu-Ti et U-Pu-Zr pour des teneurs de 15 a 20 pour cent de plutonium et 10 pour cent en poids d'element ternaire. On a determine les temperatures de transformation, les coefficients de dilatation, la nature des phases, la conductibilite thermique a 20 deg. C, la tenue au cyclage thermique et diverses autres proprietes. Un tableau resume les principales proprietes des divers alliages. On considere les possibilites d'emploi de ces alliages comme combustibles de reacteur rapide. Les alliages U-Pu-Ti paraissent particulierement interessants: facilite d'elaboration, stabilite thermique etendue, tenue dans l'air excellente, faible quantite de la phase U-Pu zeta, temperature de fusion commencante superieure a 1100 deg. C. (auteurs)

Stabilizing And Packaging Pu Materials Per 3013 At SRS

International Nuclear Information System (INIS)

STEVE, HENSEL

2005-01-01

The Savannah River Site (SRS) began packaging Pu metals into 3013 containers in April, 2003 and oxides in October, 2003. A total of 919 outer 3013 containers were made in the FB-Line at SRS when stabilization and packaging was completed in January, 2005. Experiences, lessons learned, and an overview of packaging activities are presented

Thermophysical properties of solid and liquid pure and alloyed Pu: A review

Energy Technology Data Exchange (ETDEWEB)

Boivineau, M., E-mail: michel.boivineau@cea.f [CEA, Centre de Valduc, Departement de Recherches sur les Materiaux Nucleaires, F-21120 Is-sur-Tille (France)

2009-08-01

The thermophysical properties of both solid and liquid pure and alloyed plutonium have been investigated up to 4000 K by use of a resistive pulse heating technique, the so-called isobaric expansion experiment (IEX). Electrical resistivity, specific volume (density), latent heats of transformations, heat of fusion have been measured and extended in the whole liquid region. Additional static measurements have been also performed in order to determine the heat transport properties such as heat capacity, thermal diffusivity and thermal conductivity of plutonium alloys. After a first part devoted to additional results on pure Pu under rapid heating, this paper mostly deals with studies on different delta-stabilized Pu alloys in the high temperature range, particularly in the liquid state which is the principal originality of this work. In addition to the thermophysical data mentioned above, an attention is also paid onto sound velocity measurements on these alloys in the solid and liquid states. Hence, an anomalous behavior such as elastic softening is confirmed in the delta phase as already reported previously. Moreover, sound velocity and equation of state parameters (adiabatic and thermal bulk moduli, Grueneisen parameter, and specific heats ratio) have been investigated on liquid alloyed Pu. Such results confirm previous works on liquid pure Pu by presenting an atypical dual behavior of sound velocity, and are discussed in terms of delocalization process of the 5f electrons of both liquid pure and alloyed Pu.

Study of plutonium and its alloys with III B elements

International Nuclear Information System (INIS)

Robert, Gregory

2003-12-01

The objective of this research thesis is to understand phenomena which intervene in the delta phase stabilisation of plutonium alloys, and to build phase diagrams for PuAl, PuGa, and PuIn. After a presentation of some properties of plutonium and of its compounds, the author presents the adopted approach: the 'ab initio' approach to the fundamental state based on the density functional theory (DFT). Then, a numerical method used within the framework of the DFT is developed, and results obtained by using the developed code are presented for the different studied materials (Al, Ga, In, Pu). A gradient correction is applied to the alloys by using the Generalised Gradient Approximation (GGA) with spin polarisation. It allows the determination of the formation energy of compounds. Hybridisation effects between plutonium and delta-generating elements (Al, Ga, In) are assessed. A statistic approach (cluster variation method, CVM) is used to assess the influence of the chemical order at short distance on the stability of the fcc solid solution, and to obtain theoretical binary alloy diagrams

Redox thermodynamic data of plutonium in acidic and carbonate media. Pu(V) stability

International Nuclear Information System (INIS)

Capdevila, H.

1992-01-01

Pu redox equilibria are studied in acidic and carbonate media in this thesis, to build a thermodynamic data bank consistent with the TDB (NEA-OECD) one and in connection with radioactive waste disposal programs. Literature is discussed and reinterpreted. The experimental method is tested with Uranium preliminary measurements. The reversible redox potentials (PuO 2 + and Pu 4+ /Pu 3+ ) are measured using the cyclic voltametric technique in perchloric media at several ionic strengths (from 0.5 to 3M) and temperatures (from 0 to 70 deg C). The Specific Interaction Theory (SIT) is used to measured activity coefficients and to extrapolate data to the standard conditions. The potentials variations versus temperature are linear in first approximation: the entropy changes are found constant from 0 to 70 deg C and the heat capacity changes are within uncertainties. The standard constant of PuO 2 + disproportionation into PuO 2 2+ and Pu 3+ is deduced from spectrophotometric measurements performed in perchloric media around pH=1 where Pu 4+ hydrolysis is discussed. The Pu non-reversible standard potentials (PuO 2 2+ /Pu 4+ for instance) are then calculated and validated with a spectrophotometric study of Pu 4+ formation from PuO 2 2+ and Pu 3+ in a 1M perchloric acidic solution. The Pu(VI/V) redox potential, activity coefficients and entropies are measured using the same technique in concentrated carbonate media. The limiting complex standard formation constants and the redox potential shifts (between acidic and carbonate media) are then discussed among the U, Np, Pu and Am actinides. A spectrophotometric study of the equilibrium between the complexes with 5 and 4 carbonate ligands allowed to measure Pu(IV) limiting complex stability at several ionic strengths. (author). 26 tabs., 46 figs., 95 refs

InGaAs GRINSCH-SQW lasers with novel carbon delta doped contact layer

NARCIS (Netherlands)

Shu, Y.; Li, Gang; Tan, H.H.; Jagadish, C.; Karouta, F.

1996-01-01

In conclusion, we have demonstrated the use of novel carbon delta doped layers in the contact layer of InGaAs SQW GRINSCH lasers and compared with lasers consisting of Zn bulk doped contact layers. These carbon delta doped contact layer lasers are of interest for post growth tuning of the laser

Pb-210 and Pu-239,240 in nearshore Gulf of Mexico sediments

International Nuclear Information System (INIS)

Rotter, R.J.

1985-05-01

Pb-210, Ra-226, and Pu-239,240 activities were measured in nearshore Gulf of Mexico sediments. Sediment cores were collected from the Mississippi delta, and the western Gulf of Mexico shelf. Mississippi delta cores which exhibit significantly higher sedimentation rates show larger inventories of Pb-210. The measured Pu levels from the western shelf are lower than from the delta at comparable depths. In three of the western shelf cores, the observed Pu inventory is considerably less than predicted from atmospheric flux. Therefore, Pu is not being removed to the sediment, or is being released following deposition. A key difference between these isotopes is that Pu exists in a less particle-reactive state. The ratio of excess Pb-210 to Pu levels increases with water depth in the delta and the western shelf. Water depth acts as an integrator of depth-sensitive processes. Pu scavenging is more sensitive to these processes. A sub-surface Pu maximum has been observed. Excess Pb-210 and Pu levels correlate well with sedimentation rates. This suggests that particle flux is important in removal of Pb-210 and Pu to the sediment. The flux of Mn out of the sediment is correlated with inventory data, suggesting that redox cycling of Mn may play a role in increasing Pb-210 and Pu sediment inventories. It is unclear whether the effects of increased sedimentation rates and increased Mn fluxes can be evaluated independently. Mixing of surface sediment correlates with inventory data. Increased sediment mixing allows for additional scavenging of Pb-210 and Pu from overlying waters. Mixing of sediment at depths below the mixed surface layer may play a role in increasing sediment inventories of Pb-210 and Pu

Tides Stabilize Deltas until Humans Interfere

Science.gov (United States)

Hoitink, T.; Zheng Bing, W.; Vermeulen, B.; Huismans, Y.; Kastner, K.

2017-12-01

Despite global concerns about river delta degradation caused by extraction of natural resources, sediment retention by reservoirs and sea-level rise, human activity in the world's largest deltas intensifies. In this review, we argue that tides tend to stabilize deltas until humans interfere. Under natural circumstances, delta channels subject to tides are more stable than their fluvial-dominated counterparts. The oscillatory tidal flow counteracts the processes responsible for bank erosion, which explains why unprotected tidal channels migrate only slowly. Peak river discharges attenuate the tides, which creates storage space to accommodate the extra river discharge during extreme events and as a consequence, reduce flood risk. With stronger tides, the river discharge is being distributed more evenly over the various branches in a delta, preventing silting up of smaller channels. Human interference in deltas is massive. Storm surge barriers are constructed, new land is being reclaimed and large-scale sand excavation takes place, to collect building material. Evidence from deltas around the globe shows that in human-controlled deltas the tidal motion often plays a destabilizing role. In channels of the Rhine-Meuse Delta, some 100 scour holes are identified, which relates to the altered tidal motion after completion of a storm surge barrier. Sand mining has led to widespread river bank failures in the tidally-influenced Mekong Delta. The catastrophic flood event in the Gauges-Brahmaputra Delta by Cyclone Aila, which caused the inundation of an embanked polder area for over two years, was preceded by river bank erosion at the mouths of formal tidal channels that were blocked by the embankment. Efforts to predict the developments of degrading deltas are few. Existing delta models are capable of reproducing expanding deltas, which is essentially a matter of simulating the transport of sediment from source in a catchment to the sink in a delta. Processes of soil

Thermodynamic re-assessment of the Pu–U system and its application to the ternary Pu–U–Ga system

Energy Technology Data Exchange (ETDEWEB)

Perron, A., E-mail: perron1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Turchi, P.E.A.; Landa, A.; Söderlind, P. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Ravat, B.; Oudot, B.; Delaunay, F. [CEA-Centre de Valduc, 21120 Is sur Tille (France); Kurata, M. [JAEA, Nucl. Sci. and Engn. Directorate, Tokai, Ibaraki 3191195 (Japan)

2014-11-15

Highlights: • The ab initio aided CALPHAD assessment of the Pu–U system has been realized. • The Pu–U–Ga thermodynamic database has been developed. • The δ-phase (fcc) of the Pu–U–Ga system is stabilized by Ga. • The stability of the complex η and ζ phases is promoted by U in the Pu–U–Ga system. - Abstract: Phase diagram and thermodynamic properties of the Plutonium–Uranium (Pu–U) system have been successfully re-assessed using the CALPHAD method with input from ab initio electronic-structure calculations for the bcc phase (γ-U, ∊-Pu). Results and methodology are discussed and compared with previous assessments. In addition, the already assessed Pu–Ga (Gallium) and U–Ga data are combined to build the Pu–U–Ga thermodynamic database. The predictions made using this database indicate that a small amount of U impacts the (δ-Pu) Pu–Ga phase stability by precipitating the complicated η and ζ phases that exist in the Pu–U system. Finally, the present investigation provides guidelines for further experimental studies.

Channel stability in the Mackenzie Delta, NWT: 1992/93 update

Energy Technology Data Exchange (ETDEWEB)

Carson, M A

1992-12-01

An update is presented of a previous report on channel stability in the Mackenzie Delta, prepared as part of a program dealing with sediment-related aspects of northern hydrocarbon development. The report presents an overview of proprietary literature from industry in the 1970s dealing with channel stability in the outer delta, a review of work of the Geological Survey of Canada in 1990-91 dealing with channel stability at proposed pipeline crossings in the Niglintgak, Taglu and Swimming Point areas, and a search of Russian literature dealing with hydrothermal erosion. 45 refs., 46 figs.

Photoconductivity properties of {delta}-Si doped InGaAs quantum well

Energy Technology Data Exchange (ETDEWEB)

Campo, Junior, V Leira; Marega, Junior, E; Rossi, J C; Lubyshev, D I; Gonzalez Borrero, P P; Basmaji, P [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica

1996-12-31

Full text. The semiconductors thin films with doping level near Anderson transition have high photo sensitivity in the photo conductivity regime. The maximum sensitivity of these photodetectors occurs under illumination when the system transform from semi-insulating to semi-metal. The ratio between deep and shallow levels concentration in this case should be near the unity with a total impurity concentration near 10{sup 15} cm{sup -3}, that difficult to control at the bulk doping. The frequency response in these devices are limited by absorption thickness ({approx}500-300 nm). In present work we report the results of visible-infrared photo detector (PD) preparation by using molecular beam epitaxy. For development of frequency response and wavelength range increase to infrared area we use {delta}-doped In{sub 0.2} Ga{sub 0.8} As quantum well. The doping level in {delta}-Si layer on the middle of QW was 2 x 10{sup 12} cm{sup -3}, that was enough for shift of deep levels-shallow levels concentration ratio to anderson transition in the area near QW. At the illumination all photoexcited carriers was collected by QW. The deepness of photo sensitivity space area is limiters by few nanometers near the QW, that increase the frequency properties of PD. Photo current spectra show high sensibility ({Delta}) (R/R=15%) at cut-off frequency up 1.25 eV. This explain strong optical absorption by QW in the infrared area. The future work will focalized on introducing {delta}-doped In Ga As superlattice for linearization of PD spectrum characteristics. (author)

Dominant transverse-electric polarized emission from 298 nm MBE-grown AlN-delta-GaN quantum well ultraviolet light-emitting diodes

Science.gov (United States)

Liu, Cheng; Ooi, Yu Kee; Islam, S. M.; Xing, Huili Grace; Jena, Debdeep; Zhang, Jing

2017-02-01

III-nitride based ultraviolet (UV) light emitting diodes (LEDs) are of considerable interest in replacing gas lasers and mercury lamps for numerous applications. Specifically, AlGaN quantum well (QW) based LEDs have been developed extensively but the external quantum efficiencies of which remain less than 10% for wavelengths UV wavelengths is by the use of the AlGaN-delta-GaN QW where the insertion of the delta-GaN layer can ensure the dominant conduction band (C) - heavyhole (HH) transition, leading to large transverse-electric (TE) optical output. Here, we proposed and investigated the physics and polarization-dependent optical characterizations of AlN-delta- GaN QW UV LED at 300 nm. The LED structure is grown by Molecular Beam Epitaxy (MBE) where the delta-GaN layer is 3-4 monolayer (QW-like) sandwiched by 2.5-nm AlN sub-QW layers. The physics analysis shows that the use of AlN-delta-GaN QW ensures a larger separation between the top HH subband and lower-energy bands, and strongly localizes the electron and HH wave functions toward the QW center and hence resulting in 30-time enhancement in TEpolarized spontaneous emission rate, compared to that of a conventional Al0.35Ga0.65N QW. The polarization-dependent electroluminescence measurements confirm our theoretical analysis; a dominant TE-polarized emission was obtained at 298 nm with a minimum transverse-magnetic (TM) polarized emission, indicating the feasibility of high-efficiency TEpolarized UV emitters based on our proposed QW structure.

The history and source of particulate 137Cs and 239,240Pu deposition in sediments of the Ob River Delta, Siberia

International Nuclear Information System (INIS)

Sayles, F.L.; Livingston, H.D.; Panteleyev, G.P.

1997-01-01

This paper presents the first results of a project designed to examine the transfer of particle-associated artificial radionuclides down the Ob River in Siberia to its delta over the past 5 decades. The main sources include fallout from atmospheric nuclear weapons tests and weapons complexes and test sites of the Former Soviet Union in or near the Ob watershed. The approach is to measure the accumulation of the radionuclides in undisturbed delta sediments - obtaining a record of their deposition over time. These records were found in sediments of shallow lakes apart from, and connected to, the main channel. Sediment cores were collected in the summer of 1994 using a shallow draft catamaran to reach these lakes from a support ship in the main channel. Measurements are presented on the depth distributions of 137 Cs and Pu isotopes and their inventories in a series of dated sediment cores - including one from a location in the Taz Estuary (which does not receive Ob River sediments). Sediment dating was carried out using the excess 210 Pb technique. The results obtained are compared with known information on the temporal history of releases from the various sources and characteristics of the isotopic composition of the sources. The results show that good records of radionuclide deposition indicate that the major fraction of 137 Cs and Pu isotopes deposited in these delta sediments comes from atmospheric nuclear weapons test fallout - both delivered directly from the atmosphere and from downstream transport of watershed sediments. No more than 25% of the observed inventories could be derived from other sources

Novel barium triel/tetrelides with the Pu3Pd5 structure type

International Nuclear Information System (INIS)

Duerr, Ines; Schwarz, Michael; Wendorff, Marco; Roehr, Caroline

2010-01-01

A series of ternary barium triel(M III )/tetrel(M IV )-ides Ba 3 M x III M 5-x IV (M III =Ga,In;M IV =Si,Ge,Sn;x=0-0.7) has been prepared from melts of the elements. They all crystallize with the Pu 3 Pd 5 type structure (orthorhombic, space group Cmcm) exhibiting isolated M 5 clusters of slightly distorted nido shape (square pyramids). For the silicides, where the binary border compound Ba 3 Si 5 does not exist, the Pu 3 Pd 5 type is stabilized by substituting 0.7 Si atoms per formula unit against Ga (Ba 3 Ga 0.7 Si 4.3 :a=1024.82(1),b=856.58(1),c=1024.18(1) pm, R1=0.0220) or by a very small substitution of In (Ba 3 In 0.1 Si 4.9 :a=1017.8(2),b=852.5(2),c=1020.1(3) pm, R1=0.0406). A comparable situation is found for the corresponding germanides, where 0.7 atoms of In (Ba 3 In 0.7 Ge 4.3 :a=1051.3(2),b=864.05(14),c=1054.7(3) pm, R1=0.0248) or Ga (Ba 3 Ga x Ge 5-x :a=1035.1(1),b=861.5(1),c=1036.8(1) pm, R1=0.0148) are necessary to stabilize a Ge-rich compound of this structure type. For the stannides, the situation is somewhat different, because the binary phase Ba 3 Sn 5 itself forms the Pu 3 Pd 5 type. In this case, the structure type remains stable up to a Ga content of 0.5 Ga/f.u. (Ba 3 Ga 0.5 Sn 4.5 :a=1100.41(14),b=896.19(11),c=1111.82(14) pm, R1=0.0169) and also with a substantial In content (Ba 3 In x Sn 5-x :x∼0.9(1);a=1110.5(2),b=900.0(2),c=1120.7(2) pm, R1=0.0262). As the five-atom nido cluster requires only 24 valence electrons per formula unit according to Zintl and Wade, an excess of electrons would be assumed for the binary tetrelides such as Ba 3 Sn 5 (26 v.e./f.u.) that even the maximal amount of triel substitution 0.7 M III /f.u. attained in the title compounds cannot sufficiently compensate for. An assessment of the geometric influence of varied valence electron counts however, coupled with a detailed analysis of the calculated electron densities and the partial densities of states in the energy region above the pseudo band gap at 24 v

Andreev reflections at interfaces between delta-doped GaAs and superconducting Al films

DEFF Research Database (Denmark)

Taboryski, Rafael Jozef; Clausen, Thomas; Hansen, Jørn Bindslev

1996-01-01

By placing several Si delta-doped layers close to the surface of a GaAs molecular beam epitaxy-grown crystal, we achieve a compensation of the Schottky barrier and obtain a good Ohmic contact between an in situ deposited (without breaking the vacuum) Al metallization layer and a highly modulation...

Thermodynamics of the (Sm{sub 2}Fe{sub 17-x}Ga{sub x}+H{sub 2}) system

Energy Technology Data Exchange (ETDEWEB)

Kubis, M.; Handstein, A.; Gebel, B.; Gutfleisch, O.; Mueller, K.H.; Schultz, L. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany). Inst. fuer Metallische Werkstoffe

2000-08-10

Sm{sub 2}Fe{sub 17-x}Ga{sub x} samples (with x=0, 0.5, 1, and 2) were disproportionated into SmH{sub 2} and {alpha}-(Fe,Ga) by heating the samples in 4 MPa hydrogen up to 650 C. It was possible to disproportionate even the more stable compounds with a higher Ga content under these conditions. The recombination into the original 2:17 phase was carried out by annealing in low hydrogen pressures of 2.5, 12 and 60 kPa. The values of the hydride formation enthalpy, {delta}H, and of the change of entropy, {delta}S, for the Sm{sub 2}Fe{sub 17-x}Ga{sub x} compounds were obtained by using the Van't Hoff relation. It was found that the negative {delta}H increases monotonically from 141 to 229 kJ/mol H{sub 2} and the negative {delta}S increases monotonically from 112 to 258 J/Kmol H{sub 2} for x=0 to x=2, respectively. These results show that the higher stability for the compounds with increasing Ga content is mainly attributed to the increasing negative change of entropy -{delta}S and not, as expected before, to a decrease of -{delta}H. (orig.)

Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

Directory of Open Access Journals (Sweden)

Chen Qin

2013-01-01

Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

Stability Analysis and Stabilization of T-S Fuzzy Delta Operator Systems with Time-Varying Delay via an Input-Output Approach

Directory of Open Access Journals (Sweden)

Zhixiong Zhong

2013-01-01

Full Text Available The stability analysis and stabilization of Takagi-Sugeno (T-S fuzzy delta operator systems with time-varying delay are investigated via an input-output approach. A model transformation method is employed to approximate the time-varying delay. The original system is transformed into a feedback interconnection form which has a forward subsystem with constant delays and a feedback one with uncertainties. By applying the scaled small gain (SSG theorem to deal with this new system, and based on a Lyapunov Krasovskii functional (LKF in delta operator domain, less conservative stability analysis and stabilization conditions are obtained. Numerical examples are provided to illustrate the advantages of the proposed method.

Hydroxyurea reaction with HNO2 and Pu(III) stabilization

International Nuclear Information System (INIS)

Zhu Zhaowu; He Jianyu; Zhang Zefu; Zheng Weifang; Song Tianbao; Lin Min

2004-01-01

Reaction kinetics of hydroxyurea (HU) with HNO 2 in nitric acid solution is studied. The results show that the reaction rate follows the equation as: -dc(HNO 2 )/dt=k 0 c(HNO 2 )c 1.1 (HNO 3 ) c 0 (HU), where k 0 =(0.18±0.01)L 1.1 ·mol -1.1 ·s -1 at 10 degree C and c(HNO 2 )=5 mmol/L; the activation energy is deduced to be about 63 kJ/mol. The reaction appears zero order relative to HU. Kinetic study performed at various NaNO 3 solutions shows that salt ions have little effect on the reaction rate. Excess HU can stabilize Pu(III) well in nitric solutions

Reversed phase chromatographic behaviour of Pu (III), Pu (IV) and Pu (VI) in presence of α-hydroxyisobutyric acid

International Nuclear Information System (INIS)

Jaison, P.G.; Telmore, V.M.; Kumar, Pranaw

2016-01-01

Understanding the aqueous chemistry of plutonium is important in process conditions as well as in environmental conditions. Since plutonium possesses multiple oxidation states which can coexist in solution, a reliable method for the identification of these oxidation states is essential to understand its physical and chemical processes. The identification of plutonium oxidation states is conventionally determined through a series of liquid-liquid extraction procedures using selective extractants. Spectroscopic and laser based techniques also have been used for the identification of its oxidation state in solutions. Liquid chromatographic behavior of different oxidation states of Pu and other actinide ions is reported to correlate their retention behaviour with stability constants. Objective of the present work is to study the reversed phase chromatography behavior of the three oxidation states of plutonium viz. Pu(III), Pu(IV) and Pu(VI) in presence of á-hydroxyisobutyric acid (HIBA) as an eluent

Hydrostatic-pressure-induced GAMMA-X mixing in delta-doped Al{sub x}Ga{sub 1-x}As

Energy Technology Data Exchange (ETDEWEB)

Mora-Ramos, M E [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, CP 62209 Cuernavaca, MOR. (Mexico); Duque, C A, E-mail: memora@buzon.uaem.m [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia)

2009-05-01

The mixing between GAMMA and X points in the conduction band is known to manifest in GaAs/Al{sub x}Ga{sub 1-x}As heterostructures. Application of hydrostatic pressure leads to the variation of both the GAMMA- and X-energy gaps in such a way that around P = 39 kbar, the GaAs becomes an indirect gap one. Within a narrow interval of P around this value, both minima remain almost energetically aligned. Therefore, it can be expected that some kind of mixing between the states corresponding to the delta-quantum-wells formed at those points should manifest. In this work, we investigate the occurrence of GAMMA-X mixing induced by the application of hydrostatic pressure in n-type delta doped Al{sub x}Ga{sub 1-x}As, by means of a variational scheme that uses a 2x2 Hamiltonian with the off-diagonal element being a variational potential energy. Diagonal Schroedinger-like effective mass elements are written with potential functions given by the Thomas-Fermi approximation. The effect of the hydrostatic pressure is incorporated via the dependence on P of the different input parameters in the system: energy gaps, effective masses and dielectric constant. We report the variation of the ground state of the system as a function of P.

Electronic structure and nonmagnetic character of δ -Pu-Am alloys

Czech Academy of Sciences Publication Activity Database

Shick, Alexander; Havela, L.; Kolorenč, Jindřich; Drchal, Václav; Gouder, T.; Oppeneer, P.M.

2006-01-01

Roč. 73, č. 10 (2006), 104415/1-104415/4 ISSN 1098-0121 R&D Projects: GA AV ČR(CZ) IAA100100530; GA ČR(CZ) GA202/04/1103; GA ČR(CZ) GA202/04/1055 Institutional research plan: CEZ:AV0Z1010914 Keywords : fcc -Pu-Am alloys * electronic structure * localised moments Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.107, year: 2006

PDF analysis of PuAl alloys local structure

Energy Technology Data Exchange (ETDEWEB)

Platteau, C. [CEA Valduc, 21120 Is-sur-Tille (France)], E-mail: platteau.cyril@yahoo.fr; Bruckel, P.; Ravat, B.; Delaunay, F. [CEA Valduc, 21120 Is-sur-Tille (France)

2009-03-15

For understanding singular properties of plutonium, there is a need in studying the average and local atomic structure in Pu alloys. To study the local structure of the {delta} phase, a pair distribution function (PDF) analysis was done and has shown some significant differences with the average structure.

Effect of equilibration time on Pu desorption from goethite

International Nuclear Information System (INIS)

Wong, Jennifer C.; Powell, Brian A.; Zavarin, Mavrik; Begg, James D.; Kersting, Annie B.

2015-01-01

It has been suggested that strongly sorbing ions such as plutonium may become irreversibly bound to mineral surfaces over time which has implications for near- and far-field transport of Pu. Batch adsorption-desorption data were collected as a function of time and pH to study the surface stability of Pu on goethite. Pu(IV) was adsorbed to goethite over the pH range 4.2 to 6.6 for different periods of time (1, 6, 15, 34 and 116 d). Following adsorption, Pu was leached from the mineral surface with desferrioxamine B (DFOB), a complexant capable of effectively competing with the goethite surface for Pu. The amount of Pu desorbed from the goethite was found to vary as a function of the adsorption equilibration time, with less Pu removed from the goethite following longer adsorption periods. This effect was most pronounced at low pH. Logarithmic desorption distribution ratios for each adsorption equilibration time were fit to a pH-dependent model. Model slopes decreased between 1 and 116 d adsorption time, indicating that overall Pu(IV) surface stability on goethite surfaces becomes less dependent on pH with greater adsorption equilibration time. The combination of adsorption and desorption kinetic data suggest that non-redox aging processes affect Pu sorption behavior on goethite.

The 129iodine bomb pulse recorded in Mississippi River Delta sediments: results from isotopes of I, Pu, Cs, Pb, and C

Science.gov (United States)

Oktay, S. D.; Santschi, P. H.; Moran, J. E.; Sharma, P.

2000-03-01

129I ( t1/2 = 1.56 × 10 7 yr) has both natural as well as anthropogenic sources. Anthropogenic sources from nuclear reprocessing discharges and bomb test fallout have completely overwhelmed the natural signal on the surface of the earth in the last 50 years. However, the transfer functions in and out of environmental compartments are not well known due to temporal variations in the sources of 129I and to a lack of knowledge regarding the forms of iodine. From a vertical profile of 129I/ 127I ratios in sediments located in the Mississippi Delta region in approximately 60 meters water depth, the 129I input function to this region was reconstructed. Dates in the core were assigned based on the plutonium peak at 20 cm depth (assumed to have been deposited in 1963) and the excess 210Pb profile in the same depth interval, and below that, based on the steadily decreasing 240Pu/ 239Pu ratios from a ratio of 0.18 at 22 cm to 0.05 at 57 cm depth, the 1953 horizon. These low 240Pu/ 239Pu values are attributed to low yield, close-in, tropospherically transported bomb fallout produced from the Nevada test site in the early 1950s, which had a value of about 0.035, and strongly suggest a terrestrial source for Pu isotopes. 129I/ 127I ratios increased from 2 × 10 -10 at 3 cm to 4 × 10 -10 at 20 cm, and from there decreased monotonously to pre-anthropogenic values at 53 cm and below. 129I concentrations ranged from 8-13 × 10 6 atoms/g in the top 20 cm, and decreased to values of less than 1 × 10 6 atoms/g below 50 cm. Atom ratios of 129I/ 137Cs, decay corrected to 1962, the year of maximum radionuclide production, are about 0.3, very close to the production ratios of about 0.2 during atomic bomb tests. This evidence, combined with other observations, strongly suggests that 129I in Mississippi River Delta sediments originates from atomic bomb fallout eroded from soils of the Mississippi River drainage basin, with little alteration of the isotopic ratios during transport from

Thermodynamic stabilities of MO2+x(s) (M = U, Np, Pu and Am), pourbaix diagrams

International Nuclear Information System (INIS)

Vitorge, Pierre; Faure, Marie-Helene; Vercouter, Thomas; Capdevila, Helene; Maillard, Serge

2002-01-01

The experimental solubilities of the hydrated amorphous freshly precipitated M(OH) z (am) and MO 2 (OH) z (am) compounds are often used as an upper limit for the safety assessments of deep waste repositories, since these compounds slowly transform to less soluble ones, as typically M(OH) 4 (am) to MO 2 (cr). Solubility (vs. redox potential) at pH=8, and E-pH predominance diagrams are plotted in aqueous solutions at 25degC by using thermodynamic data recently selected by the NEA-TDB review, or estimated by using classical chemical analogies for the non-redox reactions. The solubilities and relative stabilities are also calculated for the MO 2+x (s) crystalline compounds of known stabilities: U 4 O 9 (s), U 3 O 7 (s), U 3 O 8 (s) and Np 2 O 5 (s) where 2+x = 2.25, 2.33, 2.67 and 2.5 respectively. The stabilities of the other MO 2+x (s) compounds are estimated by analogy: M 4 O 9 (s) (M=U, Np, Pu), M 3 O 7 (s) and M 3 O 8 (s) (M=U, Pu), and M 2 O 5 (s) (M=Np, Am) are predicted to be more stable (i.e. less soluble), than the amorphous hydroxides. However their precipitation have never been observed at room temperature possibly for kinetic reasons or difficulties in interpreting solubility experiments. (author)

Quantifying the importance of orbital over spin correlations in delta-Pu within density-functional theory

International Nuclear Information System (INIS)

Soderlind, P

2008-01-01

The electronic structure of plutonium is studied within the density-functional theory (DFT) model. Key features of the electronic structure are correctly modeled and bonding, total energy, and electron density of states are all consistent with measure data, although the prediction of magnetism is not consistent with many observations. Here we analyze the contributions to the electronic structure arising from spin polarization, orbital polarization, and spin-orbit interaction. These effects give rise to spin and orbital moments that are of nearly equal magnitude, but anti-parallel, suggesting a magnetic-moment cancellation with a zero total moment. Quantifying the spin versus orbital effects on the bonding, total energy, and electron spectra it becomes clear that the spin polarization is much less important than the orbital correlations. Consequently, a restricted DFT approach with a non-spin polarized electronic structure can produce reasonable equation-of-state and electron spectra for (delta)-Pu when the orbital effects are accounted for. Hence, we present two non-magnetic models. One in which the spin moment is canceled by the orbital moment and another in which the spin moment (and therefore the orbital moment) is restricted to zero

Redox potentials of PuO{sub 2}{sup 2+}/PuO{sub 2}{sup +} and Pu{sup 4+}/Pu{sup 3+} at different ionic strengths and temperatures; entropy and heat capacity; Potentiels Redox des couples PuO{sub 2}{sup 2+}/PuO{sub 2}{sup +} et Pu{sup 4+}/Pu{sup 3+} a force ionique et temperature variables. Entropie et capacite calorifique

Energy Technology Data Exchange (ETDEWEB)

Capdevila, H.; Vitorge, P.

1994-05-01

The reversible redox potentials of the Plutonium couples are measured by using cyclic voltammetry, in perchloric media at ionic strength, I from 0,5 M to 3M, and temperature, T, from 5 deg C to 65 deg C. At each T, experimental results, E(T,I), are extrapolated to I = O by applying the Specific Interaction Theory (S.I.T.) to get interaction coefficients, {Delta} is element of (T), and E(T,O) (e.g. standard potentials when T = 25 deg C). At T = 25 deg C the numerical values of the potentials of all the Pu couples are nearly the same. It is then not easy to detect a systematic error due to disproportionation or redox impurity. This can explain some discrepancy on numerical values already published. We finally propose ``recommended values`` of the reversible redox potentials. As a first approximation, the variations of these potentials seem to be quite linear versus temperature: entropy variation versus T is small. But taking into account heat capacity that is involved in the E(T,I) second order derivative, usually improves the fitting. A second order expansion of {epsilon}(T) and of the Debye Huckel term, D(T) are used to propose equations that account for simultaneous ionic strength and temperature influences on G, S, Cp, H, and lg K. These equations, in particular those modelling the ionic strength influence on {Delta}S, {Delta}Cp, and {Delta}H are first checked for published mean activity coefficients of HCI and NaCI. Small discrepancy between the numerical values of entropy changes of actinides redox couples, deduced from electrochemical and calorimetric techniques are discussed. (authors). 27 refs., 6 tabs., 10 figs.

Influence of Radiation Damage and Isochronal Annealing on the Magnetic Susceptibility of Pu1-xAmx Alloys

International Nuclear Information System (INIS)

McCall, Scott K.; Fluss, Michael J.; Chung, Brandon W.; Haire, Richard G.

2008-01-01

Results of radiation damage in Pu and Pu 1-x Am x alloys studied with magnetic susceptibility, χ(T), and resistivity are presented. Damage accumulated at low temperatures increases χ(T) for all measured alloys, with the trend generally enhanced as the lattice expands. There is a trend towards saturation observable in the damage induced magnetic susceptibility data. that is not evident in similar damage induced resistivity data taken on the same specimen. A comparison of isochronal annealing curves measured by both resistivity and magnetic susceptibility on a 4.3 at% Ga stabilized δ-Pu specimen show that Stage I annealing, where interstitials begin to move, is largely transparent to the magnetic measurement. This indicates that interstitials have little impact on the damage induced increase in the magnetic susceptibility. The isochronal annealing curves of the Pu 1-x Am x alloys do not show distinct annealing stages as expected for alloys. However, samples near 20% Am concentration show an unexpected increase in magnetization beginning when specimens are annealed to 35 K. This behavior is also reflected in a time dependent increase in the magnetic susceptibility of damaged specimens indicative of first order kinetics. These results suggest there may be a metastable phase induced by radiation damage and annealing in Pu 1-x Am x alloys. (authors)

High pressure study of Pu{sub 0.92}Am{sub 0.08} binary alloy

Energy Technology Data Exchange (ETDEWEB)

Klosek, V; Faure, P; Genestier, C [CEA, Valduc, F-21120 Is-sur-Tille (France); Griveau, J C; Wastin, F [European Commission JRC, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe (Germany); Baclet, N [CEA, DRT/DTMN, F-38054 Grenoble (France)], E-mail: vincent.klosek@cea.fr

2008-07-09

The phase transitions (by means of x-ray diffraction) and electrical resistivity of a Pu{sub 0.92}Am{sub 0.08} binary alloy were determined under pressure (up to 2 GPa). The evolution of atomic volume with pressure gives detailed information concerning the degree of localization of 5f electronic states and their delocalization process. A quasi-linear V = f(P) dependence reflects subtle modifications of the electronic structure when P increases. The electrical resistivity measurements reveal the very high stability of the {delta} phase for pressures less than 0.7 GPa, since no martensitic-like transformation occurs at low temperature. Remarkable electronic behaviours have also been observed. Finally, resistivity curves have shown the temperature dependence of the phase transformations together with unexpected kinetic effects.

Transuranium perrhenates: Np(IV), Pu(IV) and (III), Am (III)

International Nuclear Information System (INIS)

Silvestre, Jean-Paul; Freundlich, William; Pages, Monique

1977-01-01

Synthesis in aqueous solution and by solid state reactions, crystallographical characterization and study of the stability of some transuranium perrhenates: Asup(n+)(ReO 4 - )sub(n) (A=Np(IV), Pu(IV), Pu(III), Am(III) [fr

Site preference and phase stability of Ti doping Ni–Mn–Ga shape memory alloys from first-principles calculations

International Nuclear Information System (INIS)

Gao, Zhiyong; Chen, Baishu; Meng, Xianglong; Cai, Wei

2013-01-01

Highlights: •Site preference and phase stability of NiMnGaTi are studied by first-principles. •The Ti atoms prefer to occupy the Ga sites in the Ni 2 MnGa austenitic phase. •The phase stability becomes worse when Ga is replaced by Ti. •The phase stability is discussed based on the densities of states. -- Abstract: The effects of Ti content on martensitic transformation and phase stability of Ni 50 Mn 25 Ga 25−x Ti x shape memory alloys were investigated from first-principles calculations based on density functional theory. The formation energy results indicate that the added Ti preferentially occupies the Ga sites in Ni 2 MnGa alloy due to the lowest formation energy. The total energy difference between austenite and martensite increases with Ti alloying, being relevant to the experimentally reported changes in martensitic transformation temperature. The phase stability of Ni 50 Mn 25 Ga 25−x Ti x austenite decreases with increasing Ti content, which results from the reduced Ni 3d–Mn 3d hybridization when Ga is replaced by Ti

Solution species of 239Pu [V] in the environment

International Nuclear Information System (INIS)

Rai, D.; Serne, R.J.; Swanson, J.L.

1978-01-01

Information regarding the oxidation states of Pu in environmental samples is needed for estimating its migration through the geologic media. Thermodynamic data were used to develop stability fields for different Pu species. The data indicate that in the Eh-pH range of natural aqueous environments, the dominant species of Pu is likely to be Pu[V] in relatively oxidizing environments and Pu[III] in reducing environments. Because of the lack of methods of determining Pu[V] in environmental samples containing trace concentrations of Pu, Pu[V] has not been previously identified in these samples. Plutonium [VI] is generally assumed to be the dominant species in relatively oxidizing environments. However, a combination of solvent extraction and spectrophotometric techniques used in this study show that solutions (> 10 -5 4 M Pu) in equilibrium with 239 Pu[IV] hydroxide contain Pu[V], which is in agreement with the thermodynamic predictions. Although this method could not be used conclusively with the remaining solutions ( -5 4 M Pu) contacting 239 Pu[IV] hydroxide and 239 PuO 2 , the solvent extraction and Eh-pH results are similar for all the samples suggesting the strong possibility that all samples contain Pu[V]. Thus the possibility, ignored in the past, that Pu[V] may be the dominant species in relatively oxidizing environments should be considered

Biogeochemical Cycling and Environmental Stability of Pu Relevant to Long-Term Stewardship of DOE Sites

Energy Technology Data Exchange (ETDEWEB)

Francis, Arokiasamy J.; Santschi, Peter H.; Honeyman, Bruce D.

2005-06-01

The overall objective of this proposed research is to understand the biogeochemical cycling of Pu in environments of interest to long-term DOE stewardship issues. Central to Pu cycling (transport initiation to immobilization) is the role of microorganisms. The hypothesis underlying this proposal is that microbial activity is the causative agent in initiating the mobilization of Pu in near-surface environments: through the transformation of Pu associated with solid phases, production of extracellular polymeric substances (EPS) carrier phases, and the creation of microenvironments. Also, microbial processes are central to the immobilization of Pu species, through the metabolism of organically complexed Pu species and Pu associated with extracellular carrier phases and the creation of environments favorable for Pu transport retardation.

Biogeochemical Cycling and Environmental Stability of Pu Relevant to Long-Term Stewardship of DOE Sites

Energy Technology Data Exchange (ETDEWEB)

Honeyman, Bruce D.

2006-06-01

The overall objective of this proposed research is to understand the biogeochemical cycling of Pu in environments of interest to long-term DOE stewardship issues. Central to Pu cycling (transport initiation to immobilization) is the role of microorganisms. The hypothesis underlying this proposal is that microbial activity is the causative agent in initiating the mobilization of Pu in near-surface environments: through the transformation of Pu associated with solid phases, production of extracellular polymeric substances (EPS) carrier phases, and the creation of microenvironments. Also, microbial processes are central to the immobilization of Pu species, through the metabolism of organically complexed Pu species and Pu associated with extracellular carrier phases and the creation of environments favorable for Pu transport retardation.

Efficiency enhancement of InGaN/GaN light-emitting diodes with pin-doped GaN quantum barrier

International Nuclear Information System (INIS)

Sirkeli, Vadim P; Al-Daffaie, Shihab; Oprea, Ion; Küppers, Franko; Hartnagel, Hans L; Yilmazoglu, Oktay; Ong, Duu Sheng

2017-01-01

Blue InGaN/GaN light-emitting diodes with undoped, heavily Si-doped, Si delta-doped, heavily Mg-doped, Mg delta-doped, and Mg–Si pin-doped GaN barrier are investigated numerically. The simulation results demonstrate that the Mg–Si pin-doping in the GaN barrier effectively reduces the polarization-induced electric field between the InGaN well and the GaN barrier in the multiple quantum well, suppresses the quantum-confined Stark effect, and enhances the hole injection and electron confinement in the active region. For this light-emitting diode (LED) device structure, we found that the turn-on voltage is 2.8 V, peak light emission is at 415.3 nm, and internal quantum efficiency is 85.9% at 100 A cm −2 . It is established that the LED device with Mg–Si pin-doping in the GaN barrier has significantly improved efficiency and optical output power performance, and lower efficiency droop up to 400 A cm −2 compared with LED device structures with undoped or Si(Mg)-doped GaN barrier. (paper)

Experience on tangent delta norms adopted for repaired generator

International Nuclear Information System (INIS)

Misra, N.N.; Sood, D.K.

2005-01-01

The repair techniques of the generators are very crucial for avoiding prolonged forced outages. The crucial decisions based on sound knowledge and judgement becomes essential in many cases. The unit under discussions had failed on account of flash over in the Exciter end overhang windings. The failure resulted in damaged to the stator bars as well as generator core. The damaged end packets of the stator core were replaced at site. The total winding bars were removed from stator core and damaged bars were replaced with new bars. The rest of the bars were tested for tangent delta tests for reuse. Acceptance norms of 0.6% tip up from 0.2pu to 0.6pu of rated stator voltage were adopted. Some of the bars outside the acceptable limits of tangent delta were shifted close to neutral so that the standard norms of tan delta are met. This was felt necessary because lead-time for procurement of new bars was more than six months. The above-adopted norms for tangent delta will be of much use for the operating utilities. The unit under discussions was of 67.5 MW operating at 50 Hz, 0.85 pf lag and had logged 66160.46 operating hours before failure. (author)

Pu-239 and Pu-240 inventories and Pu-240/ Pu-239 atom ratios in the water column off Sanriku, Japan.

Science.gov (United States)

Yamada, Masatoshi; Zheng, Jian; Aono, Tatsuo

2013-04-01

A magnitude 9.0 earthquake and subsequent tsunami occurred in the Pacific Ocean off northern Honshu, Japan, on 11 March 2011 which caused severe damage to the Fukushima Dai-ichi Nuclear Power Plant. This accident has resulted in a substantial release of radioactive materials to the atmosphere and ocean, and has caused extensive contamination of the environment. However, no information is available on the amounts of radionuclides such as Pu isotopes released into the ocean at this time. Investigating the background baseline concentration and atom ratio of Pu isotopes in seawater is important for assessment of the possible contamination in the marine environment. Pu-239 (half-life: 24,100 years), Pu-240 (half-life: 6,560 years) and Pu-241 (half-life: 14.325 years) mainly have been released into the environment as the result of atmospheric nuclear weapons testing. The atom ratio of Pu-240/Pu-239 is a powerful fingerprint to identify the sources of Pu in the ocean. The Pu-239 and Pu-240 inventories and Pu-240/Pu-239 atom ratios in seawater samples collected in the western North Pacific off Sanriku before the accident at Fukushima Dai-ichi Nuclear Power Plant will provide useful background baseline data for understanding the process controlling Pu transport and for distinguishing additional Pu sources. Seawater samples were collected with acoustically triggered quadruple PVC sampling bottles during the KH-98-3 cruise of the R/V Hakuho-Maru. The Pu-240/Pu-239 atom ratios were measured with a double-focusing SF-ICP-MS, which was equipped with a guard electrode to eliminate secondary discharge in the plasma and to enhance overall sensitivity. The Pu-239 and Pu-240 concentrations were 2.07 and 1.67 mBq/m3 in the surface water, respectively, and increased with depth; a subsurface maximum was identified at 750 m depth, and the concentrations decreased with depth, then increased at the bottom layer. The total Pu-239+240 inventory in the entire water column (depth interval 0

Biosorption of 239Pu by immobilized sargassum fusiforme

International Nuclear Information System (INIS)

Liang Zhirong; Chen Qi; Wu Yusheng

2009-01-01

Sargassum fusiforme was immobilized with calcium alginates and its biosorption property to 239 Pu was studied by batch and column methods. Biosorption equilibrium time of immobilized Sargassum fusiforme biosorbent to 239 Pu is 120 min and biosorption efficiency is over 99.2% when the initial concentration of 239 Pu is 21.5 kBq/L and pH is 2.5-5.0. After five times repetition biosorption-desorption cycles biosorption efficiency is still over 98.0% when the velocity of flow is 2 ml/min in column experiment. Immobilized Sargassum fusiforme biosorbent is better to 239 Pu due to its better chemical stability, mechanical strength, lower cost, high biosorption efficiency and repeated biosorption-desorption cycles. (authors)

Improved stability and performance from sigma-delta modulators using 1-bit vector quantization

DEFF Research Database (Denmark)

Risbo, Lars

1993-01-01

A novel class of sigma-delta modulators is presented. The usual scalar 1-b quantizer in a sigma-delta modulator is replaced by a 1-b vector quantizer with a N-dimensional input state-vector from the linear feedback filter. Generally, the vector quantizer changes the nonlinear dynamics...... of the modulator, and a proper choice of vector quantizer can improve both system stability and coding performance. It is shown how to construct the vector quantizer in order to limit the excursions in state-space. The proposed method is demonstrated graphically for a simple second-order modulator...

Anaerobic Biotransformation and Mobility of Pu and Pu-EDTA

International Nuclear Information System (INIS)

Bolton, H. Jr.; Rai, D.; Xun, L.

2005-01-01

The complexation of radionuclides (e.g., plutonium (Pu) and 60 Co) by codisposed ethylenediaminetetraacetate (EDTA) has enhanced their transport in sediments at DOE sites. Our previous NABIR research investigated the aerobic biodegradation and biogeochemistry of Pu(IV)-EDTA. Plutonium(IV) forms stable complexes with EDTA under aerobic conditions and an aerobic EDTA degrading bacterium can degrade EDTA in the presence of Pu and decrease Pu mobility. However, our recent studies indicate that while Pu(IV)-EDTA is stable in simple aqueous systems, it is not stable in the presence of relatively soluble Fe(III) compounds (i.e., Fe(OH) 3 (s)--2-line ferrihydrite). Since most DOE sites have Fe(III) containing sediments, Pu(IV) in likely not the mobile form of Pu-EDTA in groundwater. The only other Pu-EDTA complex stable in groundwater relevant to DOE sites would be Pu(III)-EDTA, which only forms under anaerobic conditions. Research is therefore needed in this brand new project to investigate the biotransformation of Pu and Pu-EDTA under anaerobic conditions. The biotransformation of Pu and Pu-EDTA under various anaerobic regimes is poorly understood including the reduction kinetics of Pu(IV) to Pu(III) from soluble (Pu(IV)-EDTA) and insoluble Pu(IV) as PuO2(am) by metal reducing bacteria, the redox conditions required for this reduction, the strength of the Pu(III)-EDTA complex, how the Pu(III)-EDTA complex competes with other dominant anoxic soluble metals (e.g., Fe(II)), and the oxidation kinetics of Pu(III)-EDTA. Finally, the formation of a stable soluble Pu(III)-EDTA complex under anaerobic conditions would require degradation of the EDTA complex to limit Pu(III) transport in geologic environments. Anaerobic EDTA degrading microorganisms have not been isolated. These knowledge gaps preclude the development of a mechanistic understanding of how anaerobic conditions will influence Pu and Pu-EDTA fate and transport to assess, model, and design approaches to stop Pu

Pu speciation in actual and simulated aged wastes

Energy Technology Data Exchange (ETDEWEB)

Lezama-pacheco, Juan S [Los Alamos National Laboratory; Conradson, Steven D [Los Alamos National Laboratory

2008-01-01

X-ray Absorption Fine Structure Spectroscopy (XAFS) at the Pu L{sub II/III} edge was used to determine the speciation of this element in (1) Hanford Z-9 Pu crib samples, (2) deteriorated waste resins from a chloride process ion-exchange purification line, and (3) the sediments from two Waste Isolation Pilot Plant Liter Scale simulant brine systems. The Pu speciation in all of these samples except one is within the range previously displayed by PuO{sub 2+x-2y}(OH){sub y}{center_dot}zH{sub 2}O compounds, which is expected based on the putative thermodynamic stability of this system for Pu equilibrated with excess H{sub 2}O and O{sub 2} under environmental conditions. The primary exception was a near neutral brine experiment that displayed evidence for partial substitution of the normal O-based ligands with Cl{sup -} and a concomitant expansion of the Pu-Pu distance relative to the much more highly ordered Pu near neighbor shell in PuO{sub 2}. However, although the Pu speciation was not necessarily unusual, the Pu chemistry identified via the history of these samples did exhibit unexpected patterns, the most significant of which may be that the presence of the Pu(V)-oxo species may decrease rather than increase the overall solubility of these compounds. Several additional aspects of the Pu speciation have also not been previously observed in laboratory-based samples. The molecular environmental chemistry of Pu is therefore likely to be more complicated than would be predicted based solely on the behavior of PuO{sub 2} under laboratory conditions.

Core level photoelectron spectroscopy of LiGaS{sub 2} and Ga-S bonding in complex sulfides

Energy Technology Data Exchange (ETDEWEB)

Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.r [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, 13, Lavrentieva Ave., Novosibirsk 90, 630090 (Russian Federation); Isaenko, L.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Kesler, V.G. [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Lobanov, S.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

2010-05-14

The electronic parameters of the lithium thiogallate LiGaS{sub 2} have been evaluated by X-ray photoelectron spectroscopy (XPS). Spectral features of all constituent element core levels and Auger lines have been considered. The Ga-S bonding effects in Ga-bearing sulfide crystals have been discussed using binding energy difference {Delta}{sub 2p}(S-Ga) = BE(S 2p) - BE(Ga 3d) as a representative parameter to quantify the valence electron shift from gallium to sulfur atoms. The value {Delta}{sub 2p}(S-Ga) = 141.9 eV found for LiGaS{sub 2} is very close to that evaluated for AgGaS{sub 2}. This relation is an indicator of closely coincident ionicity of Ga-S bonds in LiGaS{sub 2} and AgGaS{sub 2}.

Pu Sorption, Desorption and Intrinsic Colloid Stability under Granitic Chemical Conditions

Energy Technology Data Exchange (ETDEWEB)

Zhao, Pihong [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dai, Zurong [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kersting, Annie B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-09-04

This progress report (M4FT-14LL0807031) describes research conducted at LLNL as part of the Crystalline Repository effort within the UFD program. Part I describes the dissolution kinetics of intrinsic Pu colloids synthesized in an alkaline solution. Part II describes the morphology and dissolution characteristics of various forms of Pu oxides prepared over a range of solution and temperature conditions. Proposed FY15 activities are identified.

Selfsimilar and fractal analysis of n-type delta-doped quasiregular GaAs quantum wells

International Nuclear Information System (INIS)

García-Cervantes, H.; Rodríguez-Vargas, I.

2014-01-01

We study the electronic structure of n-type delta-doped quantum wells in GaAs in which the multiple well system is built according to the Fibonacci sequence. The building blocks A and B correspond to delta-doped wells with impurities densities n 2DA and n 2DB , and the same well width. The Thomas-Fermi approximation, the semi-empirical sp 3 s* tight-binding model including spin, the Surface Green Function Matching method and the Transfer Matrix approach were implemented to obtain the confining potential, the electronic structure and the selfsimilarity of the spectrum. The fragmentation of the electronic spectra is observed whenever the building blocks A and B interact and it increases as the difference of impurities density between A and B increases as well. The wave function of the first sate of the fragmented bands presents critical characteristics, this is, it is not a localized state nor a extended one as well as it has selfsimilar features. So, the quasiregular characteristics are preserved irrespective of the complexity of the system and can affect the performance of devices based on these structures

Selfsimilar and fractal analysis of n-type delta-doped quasiregular GaAs quantum wells

Energy Technology Data Exchange (ETDEWEB)

García-Cervantes, H.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)

2014-05-15

We study the electronic structure of n-type delta-doped quantum wells in GaAs in which the multiple well system is built according to the Fibonacci sequence. The building blocks A and B correspond to delta-doped wells with impurities densities n{sub 2DA} and n{sub 2DB}, and the same well width. The Thomas-Fermi approximation, the semi-empirical sp{sub 3}s* tight-binding model including spin, the Surface Green Function Matching method and the Transfer Matrix approach were implemented to obtain the confining potential, the electronic structure and the selfsimilarity of the spectrum. The fragmentation of the electronic spectra is observed whenever the building blocks A and B interact and it increases as the difference of impurities density between A and B increases as well. The wave function of the first sate of the fragmented bands presents critical characteristics, this is, it is not a localized state nor a extended one as well as it has selfsimilar features. So, the quasiregular characteristics are preserved irrespective of the complexity of the system and can affect the performance of devices based on these structures.

Endohedral gallide cluster superconductors and superconductivity in ReGa5.

Science.gov (United States)

Xie, Weiwei; Luo, Huixia; Phelan, Brendan F; Klimczuk, Tomasz; Cevallos, Francois Alexandre; Cava, Robert Joseph

2015-12-22

We present transition metal-embedded (T@Gan) endohedral Ga-clusters as a favorable structural motif for superconductivity and develop empirical, molecule-based, electron counting rules that govern the hierarchical architectures that the clusters assume in binary phases. Among the binary T@Gan endohedral cluster systems, Mo8Ga41, Mo6Ga31, Rh2Ga9, and Ir2Ga9 are all previously known superconductors. The well-known exotic superconductor PuCoGa5 and related phases are also members of this endohedral gallide cluster family. We show that electron-deficient compounds like Mo8Ga41 prefer architectures with vertex-sharing gallium clusters, whereas electron-rich compounds, like PdGa5, prefer edge-sharing cluster architectures. The superconducting transition temperatures are highest for the electron-poor, corner-sharing architectures. Based on this analysis, the previously unknown endohedral cluster compound ReGa5 is postulated to exist at an intermediate electron count and a mix of corner sharing and edge sharing cluster architectures. The empirical prediction is shown to be correct and leads to the discovery of superconductivity in ReGa5. The Fermi levels for endohedral gallide cluster compounds are located in deep pseudogaps in the electronic densities of states, an important factor in determining their chemical stability, while at the same time limiting their superconducting transition temperatures.

Thermal stability study of Cr/Au contact formed on n-type Ga-polar GaN, N-polar GaN, and wet-etched N-polar GaN surfaces

International Nuclear Information System (INIS)

Choi, Yunju; Kim, Yangsoo; Ahn, Kwang-Soon; Kim, Hyunsoo

2014-01-01

Highlights: • The Cr/Au contact on n-type Ga-polar (0 0 0 1) GaN, N-polar (0 0 0 −1) GaN, and wet-etched N-polar GaN were investigated. • Thermal annealing led to a significant degradation of contact formed on N-polar n-GaN samples. • Contact degradation was shown to be closely related to the increase in the electrical resistivity of n-GaN. • Out-diffusion of Ga and N atoms was clearly observed in N-polar samples. - Abstract: The electrical characteristics and thermal stability of a Cr/Au contact formed on n-type Ga-polar (0 0 0 1) GaN, N-polar GaN, and wet-etched N-polar GaN were investigated. As-deposited Cr/Au showed a nearly ohmic contact behavior for all samples, i.e., the specific contact resistance was 3.2 × 10 −3 , 4.3 × 10 −4 , and 1.1 × 10 −3 Ω cm 2 for the Ga-polar, flat N-polar, and roughened N-polar samples, respectively. However, thermal annealing performed at 250 °C for 1 min in a N 2 ambient led to a significant degradation of contact, i.e., the contact resistance increased by 186, 3260, and 2030% after annealing for Ga-polar, flat N-polar, and roughened N-polar samples, respectively. This could be due to the different disruption degree of Cr/Au and GaN interface after annealing, i.e., the insignificant interfacial reaction occurred in the Ga-polar sample, while out-diffusion of Ga and N atoms was clearly observed in N-polar samples

Thermal stability study of Cr/Au contact formed on n-type Ga-polar GaN, N-polar GaN, and wet-etched N-polar GaN surfaces

Energy Technology Data Exchange (ETDEWEB)

Choi, Yunju [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Suncheon Center, Korea Basic Science Institute, Suncheon 540-742 (Korea, Republic of); Kim, Yangsoo [Suncheon Center, Korea Basic Science Institute, Suncheon 540-742 (Korea, Republic of); Ahn, Kwang-Soon, E-mail: kstheory@ynu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Kim, Hyunsoo, E-mail: hskim7@jbnu.ac.kr [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

2014-10-30

Highlights: • The Cr/Au contact on n-type Ga-polar (0 0 0 1) GaN, N-polar (0 0 0 −1) GaN, and wet-etched N-polar GaN were investigated. • Thermal annealing led to a significant degradation of contact formed on N-polar n-GaN samples. • Contact degradation was shown to be closely related to the increase in the electrical resistivity of n-GaN. • Out-diffusion of Ga and N atoms was clearly observed in N-polar samples. - Abstract: The electrical characteristics and thermal stability of a Cr/Au contact formed on n-type Ga-polar (0 0 0 1) GaN, N-polar GaN, and wet-etched N-polar GaN were investigated. As-deposited Cr/Au showed a nearly ohmic contact behavior for all samples, i.e., the specific contact resistance was 3.2 × 10{sup −3}, 4.3 × 10{sup −4}, and 1.1 × 10{sup −3} Ω cm{sup 2} for the Ga-polar, flat N-polar, and roughened N-polar samples, respectively. However, thermal annealing performed at 250 °C for 1 min in a N{sub 2} ambient led to a significant degradation of contact, i.e., the contact resistance increased by 186, 3260, and 2030% after annealing for Ga-polar, flat N-polar, and roughened N-polar samples, respectively. This could be due to the different disruption degree of Cr/Au and GaN interface after annealing, i.e., the insignificant interfacial reaction occurred in the Ga-polar sample, while out-diffusion of Ga and N atoms was clearly observed in N-polar samples.

{sup 239}Pu and {sup 240}Pu inventories and {sup 240}Pu/{sup 239}Pu atom ratios in the equatorial Pacific Ocean water column

Energy Technology Data Exchange (ETDEWEB)

Yamada, Masatoshi, E-mail: myamada@cc.hirosaki-u.ac.jp [Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori 036-8564 (Japan); Zheng, Jian [Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)

2012-07-15

The {sup 239+240}Pu concentrations and {sup 240}Pu/{sup 239}Pu atom ratios were determined by alpha spectrometry and inductively coupled plasma mass spectrometry for seawater samples from two stations, one at the equator and the other in the equatorial South Pacific. To better understand the fate of Pu isotopes, this study dealt with the contribution of the close-in fallout Pu from the Pacific Proving Grounds (PPG) in water columns of the Pacific Ocean. The {sup 239}Pu, {sup 240}Pu and {sup 239+240}Pu inventories over the depth interval 0-3000 m at the equator station were 10.4, 8.9 and 19.3 Bq m{sup -2}, respectively. Further, no noticeable difference was observed in {sup 239}Pu, {sup 240}Pu and {sup 239+240}Pu inventories over the depth interval 0-3000 m between the two stations. The total {sup 239+240}Pu inventories were significantly higher than the expected cumulative deposition density of global fallout. Water column {sup 239+240}Pu inventories measured in this study were lower than those reported for comparable stations in the Geochemical Ocean Sections Study, indicating that these inventories have been decreasing at average rates of 0.89 {+-} 0.07 and 0.16 {+-} 0.07 Bq m{sup -2} yr{sup -1} at the equator and equatorial South Pacific stations, respectively, from 1973 to 1990. The obtained {sup 240}Pu/{sup 239}Pu atom ratios were higher than the mean global fallout ratio of 0.18. These high atom ratios proved the existence of close-in tropospheric fallout Pu from the PPG in the Marshall Islands. The {sup 239+240}Pu inventories originating from the close-in fallout in the entire water column were estimated to be 11.1 Bq m{sup -2} at the equator station and 7.1 Bq m{sup -2} at the equatorial South Pacific Ocean station, and the relative percentages of close-in fallout Pu were 40% at the former and 34% at the latter. A significant amount of close-in fallout Pu originating from the PPG has been transported to deep layers below the 1000 m depth in the equatorial

A study of accelerated radiation damage effects in PuO{sub 2} and gadolinia-stabilized cubic zirconia, Zr{sub 0.79}Gd{sub 0.14}Pu{sub 0.07}O{sub 1.93}, doped with {sup 238}Pu

Energy Technology Data Exchange (ETDEWEB)

Burakov, B.E., E-mail: burakov@peterlink.ru [V.G. Khlopin Radium Institute, 28, 2-nd Murinskiy Ave., St. Petersburg, 194021 (Russian Federation); Yagovkina, M.A. [A.F. Ioffe Physical-Technical Institute, 26, Politekhnicheskaya, St. Petersburg, 194021 (Russian Federation)

2015-12-15

Polycrystalline samples of cubic zirconia, Zr{sub 0.79}Gd{sub 0.14}Pu{sub 0.07}O{sub 1.93}, doped with approximately 9.9 wt.% {sup 238}Pu, and PuO{sub 2} containing 11.0 wt. % {sup 238}Pu (and main isotope is {sup 239}Pu) have been repeatedly studied during many years by X-ray diffraction analysis. At a temperature of 25 °C the unit-cell parameter of PuO{sub 2} increases depending on accumulated dose, and is accompanied by decrease of coherent scattering region (CSR). Self-irradiation of Zr{sub 0.79}Gd{sub 0.14}Pu{sub 0.07}O{sub 1.93} is accompanied with repeated change of unit-cell parameter and CSR.

Charge distribution studies in the fast-neutron-induced fission of sup 2 sup 3 sup 2 Th, sup 2 sup 3 sup 8 U, sup 2 sup 4 sup 0 Pu and sup 2 sup 4 sup 4 Cm

CERN Document Server

Naik, H; Iyer, R H

2003-01-01

Charge distribution studies for heavy-mass fission products were carried out in the fast-neutron-induced fission of sup 2 sup 3 sup 2 Th, sup 2 sup 3 sup 8 U, sup 2 sup 4 sup 0 Pu and sup 2 sup 4 sup 4 Cm using radiochemical and gamma-ray spectrometric techniques. The width parameter(sigma sub Z /sigma sub A), the most probable charge/mass (Z sub P /A sub P), the charge polarization (DELTA Z) and the slope of charge polarization [ delta(DELTA Z)/delta A sup '] as a function of the fragment mass (A sup ') were deduced. The average charge dispersion parameter (left angle sigma sub Z right angle) and proton odd-even effect (delta sub p) were also obtained for these fissioning systems. The left angle sigma sub Z right angle and delta sub p values in the fissioning systems sup 2 sup 4 sup 1 Pu sup * and sup 2 sup 4 sup 5 Cm sup * were determined for the first time. The delta(DELTA Z)/delta A sup ' value is also determined for the first time in the fissioning systems sup 2 sup 3 sup 9 U sup * , sup 2 sup 4 sup 1 Pu...

Structural stability and elastic properties of L12 Co3(Ga,W) precipitate from first-principle calculations

International Nuclear Information System (INIS)

Yao Qiang; Zhu Yuhong; Wang Yan

2011-01-01

Ultrasoft pseudopotential within a generalized gradient approximation was employed to study the structural stability, electronic structure, and elastic properties of ternary Co 3 (Ga,W) precipitate. The Young's and shear moduli of the polycrystals containing the Co 3 (Ga,W) precipitate were calculated using the Voigt-Reuss-Hill averaging scheme. Results show that the stable ternary Co 3 (Ga,W) compound has the L1 2 structure, and is ductile in nature. The structural stability of the Co 3 (Ga,W) compound is discussed together with the calculated electronic structure.

Biodegradation of PuEDTA and Impacts on Pu Mobility

International Nuclear Information System (INIS)

Bolton, H. Jr.; Rai, D.; Xun, L.

2004-01-01

The contamination of many DOE sites by Pu presents a long-term problem because of its long half-life (240,000 yrs) and the low drinking water standard ( -12 M). EDTA was co-disposed with radionuclides (e.g., Pu, 60 Co), formed strong complexes, and enhanced radionuclide transport at several DOE sites. Biodegradation of EDTA should decrease Pu mobility. One objective of this project was to determine the biodegradation of EDTA in the presence of PuEDTA complexes. The aqueous system investigated at pH 7 (10 -4 M EDTA and 10 -6 M Pu) contained predominantly Pu(OH) 2 EDTA 2- . The EDTA was degraded at a faster rate in the presence of Pu. As the total concentration of both EDTA and PuEDTA decreased (i.e., 10 -5 M EDTA and 10 -7 M PuEDTA), the presence of Pu decreased the biodegradation rate of the EDTA. It is currently unclear why the concentration of Pu directly affects the increase/decrease in rate of EDTA biodegradation. The soluble Pu concentration decreased, in agreement with thermodynamic predictions, as the EDTA was biodegraded, indicating that biodegradation of EDTA will decrease Pu mobility when the Pu is initially present as Pu(IV)EDTA. A second objective was to investigate how the presence of competing metals, commonly encountered in geologic media, will influence the speciation and biodegradation of Pu(IV)-EDTA. Studies on the solubilities of Fe(OH) 3 (s) and of Fe(OH) 3 (s) plus PuO 2 (am) in the presence of EDTA and as a function of pH showed that Fe(III) out competes the Pu(IV) for the EDTA complex, thereby showing that Pu(IV) will not form stable complexes with EDTA for enhanced transport of Pu in Fe(III) dominated subsurface systems. A third objective is to investigate the genes and enzymes involved in EDTA biodegradation. BNC1 can use EDTA and another synthetic chelating agent nitrilotriacetate (NTA) as sole carbon and nitrogen sources. The same catabolic enzymes are responsible for both EDTA and NTA degradation except that additional enzymes are

Thermal stability studies on atomically clean and sulphur passivated InGaAs surfaces

Energy Technology Data Exchange (ETDEWEB)

Chauhan, Lalit; Hughes, Greg [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2013-03-15

High resolution synchrotron radiation core level photoemission measurements have been used to study the high temperature stability of sulphur passivated InGaAs surfaces and comparisons made with atomically clean surfaces subjected to the same annealing temperatures. Sulphur passivation of clean InGaAs surfaces prepared by the thermal removal of an arsenic capping layer was carried out using an in situ molecular sulphur treatment in ultra high vacuum. The elemental composition of the surfaces of these materials was measured at a series of annealing temperatures up to 530 C. Following a 480 C anneal In:Ga ratio was found to have dropped by 33% on sulphur passivated surface indicating a significant loss of indium, while no drop in indium signal was recorded at this temperature on the atomically InGaAs surface. No significant change in the As surface concentration was measured at this temperature. These results reflect the reduced thermal stability of the sulphur passivated InGaAs compared to the atomically clean surface which has implications for device fabrication. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Investigation of the oxidation states of Pu isotopes in a hydrochloric acid solution

Energy Technology Data Exchange (ETDEWEB)

Lee, M.H. [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, P. O. Box 105, Yuseong, Daejeon 305-353 (Korea, Republic of)], E-mail: mhlee@kaeri.re.kr; Kim, J.Y.; Kim, W.H.; Jung, E.C.; Jee, K.Y. [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, P. O. Box 105, Yuseong, Daejeon 305-353 (Korea, Republic of)

2008-12-15

The characteristics of the oxidation states of Pu in a hydrochloric acid solution were investigated and the results were applied to a separating of Pu isotopes from IAEA reference soils. The oxidation states of Pu(III) and Pu(IV) were prepared by adding hydroxylamine hydrochloride and sodium nitrite to a Pu stock solution, respectively. Also, the oxidation state of Pu(VI) was adjusted with concentrated HNO{sub 3} and HClO{sub 4}. The stability of the various oxidation states of plutonium in a HCl solution with elapsed time after preparation were found to be in the following order: Pu(III){approx}Pu(VI)>Pu(IV)>Pu(V). The chemical recoveries of Pu(IV) in a 9 M HCl solution with an anion exchange resin were similar to those of Pu(VI). This method for the determination of Pu isotopes with an anion exchange resin in a 9 M HCl medium was applied to IAEA reference soils where the activity concentrations of {sup 239,240}Pu and {sup 238}Pu in IAEA-375 and IAEA-326 were consistent with the reference values reported by the IAEA.

Interatomic potentials for PuC by Chen–Möbius multiple lattice inversion

International Nuclear Information System (INIS)

Huang, H.; Meng, D.Q.; Lai, X.C.; Li, G.; Long, Y.

2013-01-01

The atomic interactions of PuC with B1 structure were described by Chen–Möbius lattice inversion combined with first-principle calculations. In order to obtain the inversion potential parameters of PuC, three different structures including two virtual crystals were built and the Morse function plus a modified term was adopted to fit the pair-potential curves. The reliability of the inversion potential was tested by checking the stability of the transition of PuC from disordered to ordered state and comparing the calculated and experimental physical and thermal properties of PuC. All the results show that the inversion potential could give a stable and accurate description of the atomic interactions in PuC and the physical and thermal properties of PuC are well reproduced by the potential

Determination of plutonium isotopes (238Pu, 239Pu, 240Pu, 241Pu) in environmental samples using radiochemical separation combined with radiometric and mass spectrometric measurements.

Science.gov (United States)

Xu, Yihong; Qiao, Jixin; Hou, Xiaolin; Pan, Shaoming; Roos, Per

2014-02-01

This paper reports an analytical method for the determination of plutonium isotopes ((238)Pu, (239)Pu, (240)Pu, (241)Pu) in environmental samples using anion exchange chromatography in combination with extraction chromatography for chemical separation of Pu. Both radiometric methods (liquid scintillation counting and alpha spectrometry) and inductively coupled plasma mass spectrometry (ICP-MS) were applied for the measurement of plutonium isotopes. The decontamination factors for uranium were significantly improved up to 7.5 × 10(5) for 20 g soil compared to the level reported in the literature, this is critical for the measurement of plutonium isotopes using mass spectrometric technique. Although the chemical yield of Pu in the entire procedure is about 55%, the analytical results of IAEA soil 6 and IAEA-367 in this work are in a good agreement with the values reported in the literature or reference values, revealing that the developed method for plutonium determination in environmental samples is reliable. The measurement results of (239+240)Pu by alpha spectrometry agreed very well with the sum of (239)Pu and (240)Pu measured by ICP-MS. ICP-MS can not only measure (239)Pu and (240)Pu separately but also (241)Pu. However, it is impossible to measure (238)Pu using ICP-MS in environmental samples even a decontamination factor as high as 10(6) for uranium was obtained by chemical separation. © 2013 Elsevier B.V. All rights reserved.

Study of U - Pu - Fe alloys (Masurca critical experiment)

International Nuclear Information System (INIS)

Barthelemy, P.; Boucher, R.

1965-01-01

Three compositions have been studied: 73.5 U - 25 Pu - 1.5 Fe (weight %) 74 U - 25 Pu - 1 Fe 74.5 U - 25 Pu - 0.5 Fe Elaboration and Casting are easy. After two weeks in air 74.5 U - 25 Pu - 0.5 Fe alloys are reduced in powder. As-cast alloys containing 1 and 1,5% Fe are kept undamaged during several months. A rapid oxidisation of the alloys is however observed when the samples undergo the phase transformation (at 595 deg. C and 590 deg. C respectively). Ignition tests in the presence of air show that the oxidisation starts at about 250 deg. C and that the reaction does not spread. Ignition is not observed during heating from 20 to 660 deg. C. The transformation temperature, the melting temperature and the thermal expansion coefficients have been determined by dilatometry. Below the transformation temperature, the principal phases are U-Pu zeta and (U, Pu) 6 Fe. Thermal conductibility, Young modulus, density and heat of fusion have been measured. Compatibility tests show that between U-Pu-Fe and stainless steel a phase of (U, Pu) 6 Fe type is formed. The 74 U - 25 Pu - 1% Fe alloy seems to behave better than 73.5 U - 25 Pu - 1.5% Fe alloy because the (U, Pu) 6 Fe layer is two or three times smaller. Finally, the thermal stability has been studied with the 74 U - 25 Pu - 1% Fe alloy. A dilatometric anomaly (very weak expansion) occurs when the sample is heated above transformation temperature and cooled. But there is no anomaly by thermal cycling from 50 deg. C to 400 deg. C and there is no deterioration of alloys by heat treatments at 100 deg. C, 200 deg. C, 300 deg. C during 5 months under vacuum. (authors) [fr

Multi-isotopic determination of plutonium (239Pu, 240Pu, 241Pu and 242Pu) in marine sediments using sector-field inductively coupled plasma mass spectrometry.

Science.gov (United States)

Donard, O F X; Bruneau, F; Moldovan, M; Garraud, H; Epov, V N; Boust, D

2007-03-28

Among the transuranic elements present in the environment, plutonium isotopes are mainly attached to particles, and therefore they present a great interest for the study and modelling of particle transport in the marine environment. Except in the close vicinity of industrial sources, plutonium concentration in marine sediments is very low (from 10(-4) ng kg(-1) for (241)Pu to 10 ng kg(-1) for (239)Pu), and therefore the measurement of (238)Pu, (239)Pu, (240)Pu, (241)Pu and (242)Pu in sediments at such concentration level requires the use of very sensitive techniques. Moreover, sediment matrix contains huge amounts of mineral species, uranium and organic substances that must be removed before the determination of plutonium isotopes. Hence, an efficient sample preparation step is necessary prior to analysis. Within this work, a chemical procedure for the extraction, purification and pre-concentration of plutonium from marine sediments prior to sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) analysis has been optimized. The analytical method developed yields a pre-concentrated solution of plutonium from which (238)U and (241)Am have been removed, and which is suitable for the direct and simultaneous measurement of (239)Pu, (240)Pu, (241)Pu and (242)Pu by SF-ICP-MS.

Savannah River Laboratory monthly report: 238Pu fuel form processes

International Nuclear Information System (INIS)

1976-01-01

Progress in the Savannah River 238 Pu Fuel Form Program is discussed. Goals of the Savannah River Laboratory (SRL) program are to provide technical support for the transfer of the 238 Pu fuel form fabrication operations from Mound Laboratory to new facilities being built at the Savannah River Plant (SRP), to provide the technical basis for 238 Pu scrap recovery at SRP, and to assist in sustaining plant operations. During the period it was found that the density of hot-pressed 238 PuO 2 pellets decreased as the particle size of ball-milled powder decreased;the surface area of calcined 238 PuO 2 powder increased with increasing precipitation temperature and may be related to the variation in ball-milling response observed among different H Area B-Line batches; calcined PuO 2 produced by Pu(III) reverse-strike precipitation was directly fabricated into a pellet without ball milling, slugging, or sharding. The pellet had good appearance with acceptable density and dimensional stability, and heat transfer measurements and calculations showed that the use of hollow aluminum sleeves in the plutonium fuel fabrication (PuFF) storage vault reduced the temperature of shipping cans to 170 0 C and will reduce the temperature at the center of pure plutonium oxide (PPO) spheres to 580 0 C

Probing phonons in plutonium

International Nuclear Information System (INIS)

Wong, Joe; Krisch, M.; Farber, D.; Occelli, F.; Schwartz, A.; Chiang, T.C.; Wall, M.; Boro, C.; Xu, Ruqing

2010-01-01

Plutonium (Pu) is well known to have complex and unique physico-chemical properties. Notably, the pure metal exhibits six solid-state phase transformations with large volume expansions and contractions along the way to the liquid state: α → β → γ → (delta) → (delta)(prime) → (var e psilon) → liquid. Unalloyed Pu melts at a relatively low temperature ∼640 C to yield a higher density liquid than that of the solid from which it melts, (Figure 1). Detailed understanding of the properties of plutonium and plutonium-based alloys is critical for the safe handling, utilization, and long-term storage of these important, but highly toxic materials. However, both technical and and safety issues have made experimental observations extremely difficult. Phonon dispersion curves (PDCs) are key experimenta l data to the understanding of the basic properties of Pu materials such as: force constants, sound velocities, elastic constants, thermodynamics, phase stability, electron-phonon coupling, structural relaxation, etc. However, phonon dispersion curves (PDCs) in plutonium (Pu) and its alloys have defied measurement for the past few decades since the discovery of this element in 1941. This is due to a combination of the high thermal-neutron absorption cross section of plutonium and the inability to grow the large single crystals (with dimensions of a few millimeters) necessary for inelastic neutron scattering. Theoretical simulations of the Pu PDC continue to be hampered by the lack of suitable inter -atomic potentials. Thus, until recently the PDCs for Pu and its alloys have remained unknown experimentally and theoretically. The experimental limitations have recently been overcome by using a tightly focused undulator x-ray micro-beam scattered from single -grain domains in polycrystalline specimens. This experimental approach has been applied successfully to map the complete PDCs of an fcc d-Pu-Ga alloy using the high resolution inelastic x-ray scattering (HRIXS

Migration of plutonium from freshwater ecosystem at Hanford. [/sup 238/Pu, /sup 239/Pu, /sup 240/Pu

Energy Technology Data Exchange (ETDEWEB)

Emery, R. M.; Klopfer, D. C.; McShane, M. C.

1977-09-01

A reprocessing waste pond at Hanford has been inventoried to determine quantities of plutonium (Pu) that have been accumulated since its formation in 1944. Expressions of export were developed from these inventory data and from informed assumptions about the vectors which act to mobilize material containing Pu. This 14-acre pond provides a realistic illustration of the mobility of Pu in a lentic ecosystem. The ecological behavior of Pu in this pond is similar to that in other contaminated aquatic systems having widely differing limnological characteristics. Since its creation, this pond has received about one Ci of /sup 239/,/sup 240/Pu and /sup 238/Pu, most of which has been retained by its sediments. Submerged plants, mainly diatoms and Potamogeton, accumulate >95% of the Pu contained in biota. Emergent insects are the only direct biological route of export, mobilizing about 5 x 10/sup 3/ nCi of Pu annually, which is also the estimated maximum quantity of the Pu exported by waterfowl, birds and mammals collectively. There is no apparent significant export by wind, and it is not likely that Pu has migrated to the ground water below U-Pond via percolation. Although this pond has a rapid flushing rate, a eutrophic nutrient supply with a diverse biotic profile, and interacts with an active terrestrial environment, it appears to effectively bind Pu and prevent it from entering pathways to man and other life.

Nanoblast synthesis and consolidation of (La0.8Sr0.2)(Ga0.9Mg0.1)O(3-delta) under Spark plasma sintering conditions.

Science.gov (United States)

Vasylkiv, Oleg; Borodianska, Hanna; Badica, Petre; Zhen, Yongda; Tok, Alfred

2009-01-01

Four-cation nanograined strontium and magnesium doped lanthanum gallate (La0.8Sr0.2) (Ga0.9Mg0.1)O(3-delta) (LSGM) and its composite with 2 wt% of ceria (LSGM-Ce) were prepared. Morphologically homogeneous nanoreactors, i.e., complex intermediate metastable aggregates of desired composition were assembled by spray atomization technique, and subsequently loaded with nanoparticles of highly energetic C3H6N6O6. Rapid nanoblast calcination technique was applied and the final composition was synthesized within the preliminary localized volumes of each single nanoreactor on the first step of spark plasma treatment. Subsequent SPS consolidations of nanostructured extremely active LSGM and LSGM-Ce powders were achieved by rapid treatment under pressures of 90-110 MPa. This technique provided the heredity of the final structure of nanosize multimetal oxide, allowed the prevention of the uncontrolled agglomeration during multicomponent aggregates assembling, subsequent nanoblast calcination, and final ultra-rapid low-temperature SPS consolidation of nanostructured ceramics. LaSrGaMgCeO(3-delta) nanocrystalline powder consisting of approximately 11 nm crystallites was consolidated to LSGM-Ce nanoceramic with average grain size of approximately 14 nm by low-temperature SPS at 1250 degrees C. Our preliminary results indicate that nanostructured samples of (La0.8Sr0.2)(Ga0.9Mg0.1)O(3-delta) with 2 wt% of ceria composed of approximataley 14 nm grains can exhibit giant magnetoresistive effect in contrast to the usual paramagnetic properties measured on the samples with larger grain size.

Review of Calculations on Point Defect Properties in Delta-Pu

Energy Technology Data Exchange (ETDEWEB)

Allen, P. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wolfer, W. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-09-08

The results of theoretical predictions of properties for vacancies and self-interstitial atoms (SIA) in δ-Pu are presented and reviewed. Three methods have been used for these predictions, namely the modified embedded atom method (MEAM), density functional theory (DFT) with and without spin polarization, and continuum mechanics (CM) models adapted to plutonium. The properties considered are formation and migration energies, and relaxation volumes of vacancies and SIA. Predicted values vary considerably. Nevertheless, all three methods predict that the activation energy for self-diffusion by vacancies is of similar magnitude as the SIA formation energy. Furthermore, the absolute magnitudes of relaxation volumes for vacancies and SIA are also similar, indicating that there exist no large bias for radiation-induced void swelling.

Review of Calculations on Point Defect Properties in Delta-Pu

International Nuclear Information System (INIS)

Allen, P. G.; Wolfer, W. G.

2015-01-01

The results of theoretical predictions of properties for vacancies and self-interstitial atoms (SIA) in δ-Pu are presented and reviewed. Three methods have been used for these predictions, namely the modified embedded atom method (MEAM), density functional theory (DFT) with and without spin polarization, and continuum mechanics (CM) models adapted to plutonium. The properties considered are formation and migration energies, and relaxation volumes of vacancies and SIA. Predicted values vary considerably. Nevertheless, all three methods predict that the activation energy for self-diffusion by vacancies is of similar magnitude as the SIA formation energy. Furthermore, the absolute magnitudes of relaxation volumes for vacancies and SIA are also similar, indicating that there exist no large bias for radiation-induced void swelling.

11-year field study of Pu migration from Pu III, IV, and VI sources

International Nuclear Information System (INIS)

Kaplan, D.I.; Serkiz, S.M.; Demirkanli, D.I.; Gumapas, L.; Fjeld, R.A.; Molz, F.J.; Powell, B.A.

2005-01-01

Full text of publication follows: Understanding the processes controlling Pu mobility in the subsurface environment is important for estimating the amount of Pu waste that can be safely disposed in vadose zone burial sites. To study long-term Pu mobility, four 52-L lysimeters filled with sediment collected from the Savannah River Site near Aiken South Carolina were amended with well characterized solid Pu sources (Pu III Cl 3 , Pu IV (NO 3 ) 4 , Pu IV (C 2 O 4 ) 2 , and Pu VI O 2 (NO 3 ) 2 ) and left exposed to natural precipitation for 2 to 11 years. Pu oxidation state distribution in the Pu(III) and Pu(IV) lysimeters sediments (a red clayey sediment, pH = 6.3) were similar, consisting of 0% Pu(III), >92% Pu(IV), 1% Pu(V), 1% Pu(VI), and the remainder was a Pu polymer. These three lysimeters also had near identical sediment Pu concentration profiles, where >95% of the Pu remained within 1.25 cm of the source after 11 years; moving at an overall rate of 0.9 cm yr -1 . As expected, Pu moved more rapidly through the Pu(VI) lysimeter, at an overall rate of 12.5 cm yr -1 . Solute transport modeling of the sediment Pu concentration profile data in the Pu(VI) lysimeter indicated that some transformation of Pu into a much less mobile form, presumably Pu(IV), had occurred during the course of the two year study. This modeling also supported previous laboratory measurements showing that Pu(V) or Pu(VI) reduction was five orders of magnitude faster than corresponding Pu(III) or Pu(IV) oxidation. The slow oxidation rate (1 x 10-8 hr -1 ; t 1/2 = 8,000 yr) was not discernable from the Pu(VI) lysimeter data that reflected only two years of transport but was readily discernable from the Pu(III) and Pu(IV) lysimeter data that reflected 11 yr of transport. (authors)

²³⁹Pu and ²⁴⁰Pu inventories and ²⁴⁰Pu/²³⁹Pu atom ratios in the equatorial Pacific Ocean water column.

Science.gov (United States)

Yamada, Masatoshi; Zheng, Jian

2012-07-15

The (239+240)Pu concentrations and (240)Pu/(239)Pu atom ratios were determined by alpha spectrometry and inductively coupled plasma mass spectrometry for seawater samples from two stations, one at the equator and the other in the equatorial South Pacific. To better understand the fate of Pu isotopes, this study dealt with the contribution of the close-in fallout Pu from the Pacific Proving Grounds (PPG) in water columns of the Pacific Ocean. The (239)Pu, (240)Pu and (239+240)Pu inventories over the depth interval 0-3000 m at the equator station were 10.4, 8.9 and 19.3 Bq m(-2), respectively. Further, no noticeable difference was observed in (239)Pu, (240)Pu and (239+240)Pu inventories over the depth interval 0-3000 m between the two stations. The total (239+240)Pu inventories were significantly higher than the expected cumulative deposition density of global fallout. Water column (239+240)Pu inventories measured in this study were lower than those reported for comparable stations in the Geochemical Ocean Sections Study, indicating that these inventories have been decreasing at average rates of 0.89 ± 0.07 and 0.16 ± 0.07 Bq m(-2)yr(-1) at the equator and equatorial South Pacific stations, respectively, from 1973 to 1990. The obtained (240)Pu/(239)Pu atom ratios were higher than the mean global fallout ratio of 0.18. These high atom ratios proved the existence of close-in tropospheric fallout Pu from the PPG in the Marshall Islands. The (239+240)Pu inventories originating from the close-in fallout in the entire water column were estimated to be 11.1 Bq m(-2) at the equator station and 7.1 Bq m(-2) at the equatorial South Pacific Ocean station, and the relative percentages of close-in fallout Pu were 40% at the former and 34% at the latter. A significant amount of close-in fallout Pu originating from the PPG has been transported to deep layers below the 1000 m depth in the equatorial Pacific Ocean. Copyright © 2012 Elsevier B.V. All rights reserved.

Change Spectroscopic, thermal and mechanical studies of PU/PVC blends

Energy Technology Data Exchange (ETDEWEB)

Hezma, A.M. [Spectroscopy Department, Physics Division, National Research Center, Giza (Egypt); Elashmawi, I.S. [Spectroscopy Department, Physics Division, National Research Center, Giza (Egypt); Physic Department, Faculty of Science, Taibah University, Al-Ula (Saudi Arabia); Rajeh, A., E-mail: a.rajeh88@yahoo.com [Physic Department, Faculty of Science, Amran University, Sa' dah (Yemen); Physics Department, Faculty of science, Mansoura University, Mansoura (Egypt); Kamal, Mustafa [Physics Department, Faculty of science, Mansoura University, Mansoura (Egypt)

2016-08-15

Blends of polyurethane (PU) and polyvinyl chloride (PVC) with different concentrations were prepared by casting method. The effects of PU on PVC blends was examined by Fourier transform-infrared (FTIR), Ultra-violet visible studies (UV/VIS.), X-ray diffraction (XRD), Thermogravimetric (TGA), Differential scanning calorimetry (DSC), and mechanical properties (stress–strain curve). The interaction between PU and PVC was examined by FT-IR through the absorbance of the N–H groups and was correlated to mechanical/thermal properties. Ultra-violet visible said that optical energy gap decrease with increasing concentration of PU. Differential scanning calorimetry results was observed a single glass transition temperature (T{sub g}) for blends this confirming existence miscibility within the blends. The causes for best thermal stability of some blends may be described by measurements of interactions between C=O groups of PU and the α-hydrogen of PVC or a dipole–dipole –C=O..Cl–C– interactions. Significant alterations in FTIR, X-ray and DSC examination shows an interactions between blends had good miscibility. X-ray shows some alterations in the intensity with additional PU. PU change the mechanical behavior of PVC through of the blends. When polyurethane content increase causes polyvinyl chloride tensile strength decreases and elongation at break increase.

The reduction of Np(VI) and Pu(VI) by organic chelating agents

International Nuclear Information System (INIS)

Reed, D.T.; Aase, S.B.; Banaszak, J.E.

1998-01-01

The reduction of NpO 2+ and PuO 2 2+ by oxalate. citrate, and ethylenediaminetetraacetic acid (EDTA) was investigated in low ionic strength media and brines. This was done to help establish the stability of the An(VI) oxidation state in the presence of organic complexants. The stability of the An(VI) oxidation state depended on the pH and relative strength of the various oxidation state-specific complexes. At low ionic strength and pH 6, NpO 2 O 2+ was rapidly reduced to form NpO 2 + organic complexes. At longer times, Np(IV) organic complexes were observed in the presence of citrate. PuO 2 2+ was predominantly reduced to Pu 4+ , resulting in the formation of organic complexes or polymeric/hydrolytic precipitates. The relative rates of reduction to the An(V) complex were EDTA > citrate > oxalate. Subsequent reduction to An(IV) complexes, however, occurred in the following order: citrate > EDTA > oxalate because of the stability of the An(V)-EDTA complex. The presence of organic complexants led to the rapid reduction of NpO 2 2+ and PuO 2 P 2+ in G-seep brine at pHs 5 and 7. At pHs 8 and 10 in ERDA-6 brine, carbonate and hydrolytic complexes predominated and slowed down or prevented the reduction of An(VI) by the organics present

Schrodinger operators with delta-interactions supported on conical surfaces

Czech Academy of Sciences Publication Activity Database

Behrndt, J.; Exner, Pavel; Lotoreichik, V.

2014-01-01

Roč. 47, č. 35 (2014), s. 355202 ISSN 1751-8113 R&D Projects: GA ČR(CZ) GA14-06818S; GA MŠk 7AMB13AT010 Institutional support: RVO:61389005 Keywords : Schrödinger operator * delta potential * infinite discrete spectrum Subject RIV: BE - Theoretical Physics Impact factor: 1.583, year: 2014

Use of 236Pu and 242Pu as a radiochemical tracer for estimation of Pu in bioassay samples by fission track analysis

International Nuclear Information System (INIS)

Sawant, Pramilla D.; Prabhu, Supreetha P.; Kalsi, P.C.

2008-01-01

236 Pu and 242 Pu are routinely used as radiochemical yield monitors in India for bioassay monitoring of occupational workers by alpha spectrometry. Fission Track Analysis (FTA) is also being standardized for trace level determination of Pu in bioassay samples. The present study, reports the utility of 236 Pu and 242 Pu as radiochemical tracers in estimation of Pu in bioassay samples by FTA technique. The advantages of using 236 Pu tracer in FTA over 242 Pu as well as the interference caused due to presence of 241 Pu in the bioassay samples of occupational workers handling power reactor grade Pu is discussed. (author)

Pu(IV) reduction with hydroxyurea and its application in U/Pu separation

International Nuclear Information System (INIS)

Zhu Zhaowu; He Jianyu; Zhang Zefu; Song Tianbao; Zhang Yu; Zheng Weifang

2004-01-01

The reduction of Pu(IV) with hydroxyurea (HU) in the mixed phase of 30% TBP/OK-HNO 3 system was studied. The study results show that HU can reduce Pu(IV) to Pu(III) and the reduction rate can be expressed as -dc(Pu(IV))/dt=kc(HU)c -3.2 (HNO 3 )c mix 2 (Pu(IV))c mix -1 (Pu(III)), where k is the rate constant, and k=(896 ± 59) mol 2.3 ·L -2.3 ·min -1 at 15 degree C. With HU serves as a reductant, 16 stages count-current cascade experiment was performed using centrifugal tube to simulate U/Pu separation in the 1B contactor of Purex process. The separation factor of Pu from U and the separation factor of U from Pu reach to 5.4 x 10 4 and 1.8 x 10 5 , respectively. The amount of Pu is about 11 μg in per kg U product. (authors)

Direct spectrophotometric analysis of low level Pu (III) in Pu(IV) nitrate solution

International Nuclear Information System (INIS)

Mageswaran, P.; Suresh Kumar, K.; Kumar, T.; Gayen, J.K.; Shreekumar, B.; Dey, P.K.

2010-01-01

Among the various methods demonstrated for the conversion of plutonium nitrate to its oxide, the oxalate precipitation process either as Pu (III) or Pu (IV) oxalate gained wide acceptance. Since uranous nitrate is the most successful partitioning agent used in the PUREX process for the separation of Pu from the bulk amount of U, the Pu (III) oxalate precipitation of the purified nitrate solution will not give required decontamination from U. Hence Pu IV oxalate precipitation process is a better option to achieve the end user's specified PuO 2 product. Prior to the precipitation process, ensuring of the Pu (IV) oxidation state is essential. Hence monitoring of the level of Pu oxidation state either Pu (III) or Pu (IV) in the feed solution plays a significant role to establish complete conversion of Pu (III). The method in vogue to estimate Pu(lV) content is extractive radiometry using Theonyl Trifluoro Acetone (TTA). As the the method warrants a sample preparation with respect to acidity, a precise measurement of Pu (IV) without affecting the Pu(III) level in the feed sample is difficult. Present study is focused on the exploration of direct spectrophotometry using an optic fiber probe of path length of 40mm to monitor the low level of Pu(III) after removing the bulk Pu(lV) which interfere in the Pu(III) absorption spectrum, using TTA-TBP synergistic mixture without changing the sample acidity

Long-term stability assessment of AlGaN/GaN field effect transistors modified with peptides: Device characteristics vs. surface properties

Energy Technology Data Exchange (ETDEWEB)

Rohrbaugh, Nathaniel; Bryan, Isaac; Bryan, Zachary; Collazo, Ramon; Ivanisevic, Albena, E-mail: ivanisevic@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States)

2015-09-15

AlGaN/GaN Field Effect Transistors (FETs) are promising biosensing devices. Functionalization of these devices is explored in this study using an in situ approach with phosphoric acid etchant and a phosphonic acid derivative. Devices are terminated on peptides and soaked in water for up to 168 hrs to examine FETs for both device responses and surface chemistry changes. Measurements demonstrated threshold voltage shifting after the functionalization and soaking processes, but demonstrated stable FET behavior throughout. X-ray photoelectron spectroscopy and atomic force microscopy confirmed peptides attachment to device surfaces before and after water soaking. Results of this work point to the stability of peptide coated functionalized AlGaN/GaN devices in solution and support further research of these devices as disposable, long term, in situ biosensors.

An evaluation of a solar radiation/delta-T method for estimating Pasquill-Gifford (P-G) stability categories

Energy Technology Data Exchange (ETDEWEB)

Coulter, C.T. [Environmental Protection Agency, Research Triangle Park, NC (United States)

1994-12-31

There has been a continuing need to develop robust methods for determining Pasquill-Gifford (P-G) stability categories using solely on-site meteorological instrumentation. The Revised EPA Guideline on Air Quality Models recommends several such methods. Experience with these suggests that, since they rely on turbulence measurements, they can be unduly influenced by local effects such as mesoscale circulation (e.g., upslope/downslope flows, land/sea breeze), wakes from tree barriers or buildings, etc. to such an extent as to diminish their practical usefulness. In the following discussion, a methodology is proposed for estimating P-G stability categories that employs on-site meteorological measurements (10m wind speed coupled with solar radiation during the day and temperature difference, {Delta}T, at night) in lieu of cloud cover and ceiling height observations. The proposed method was adapted from Bowen and is herein referred to as the solar radiation/delta-T (SRDT) method. To evaluate the method, an attempt was made to acquire data bases from diverse geographical areas. Data bases with {Delta}T measurements from 2-10m above ground level were of primary interest for characterizing the boundary layer; other intervals were considered for evaluation, as available. To document the consequence of implementing the method in practical applications, an analysis was needed of the effect on design concentration ratios.

Adsorption of Th(IV) and Pu(IV) on the surface of Pseudomonas fluorescens and Bacillus subtilis in the presence of desferrioxamine siderophore

International Nuclear Information System (INIS)

Yoshida, Takahiro; Ozaki, Takuo; Ohnuki, Toshihiko; Francis, Arokiasamy J.

2005-01-01

Adsorption of Th(IV) and Pu(IV) on a Gram-negative bacterium Pseudomonas fluorescens and a Gram-positive bacterium Bacillus subtilis in the presence of siderophore desferrioxamine B (DFO) was studied. Thorium(IV) and Pu(IV) were dissociated from DFO during adsorption on the cells. Thorium(IV) adsorption on bacterial cells in the presence of DFO was larger than that of Pu(IV) because of the smaller stability of the Th(IV)-DFO complex than that of the Pu(IV)-DFO complex. On the other hand, adsorption of Pu(IV) was larger than that of Fe(III), wherein the stability of the Pu(IV)- and Fe(III)-DFO complex is comparable. P. fluorescens showed a higher affinity for Th(IV) and Pu(IV) than B. subtilis, though potentiometric titration of bacterial cells indicated that surfaces of P. fluorescens and B. subtilis cells showed similar proton binding properties. (author)

Magnetophonon resonance in photoluminescence excitation spectra of magnetoexcitons in GaAs/Al0.3Ga0.7As superlattice

DEFF Research Database (Denmark)

Dickmann, S.; Tartakovskii, A. I.; Timofeev, V. B.

2000-01-01

A strong increase in the intensity of the peaks of excited magnetoexciton (ME) states in the photoluminescence excitation (PLE) spectra recorded for the ground heavy-hole magnetoexcitons (of the 1sHH type) has been found in a GaAs/Al0.3Ga0.7As superlattice in strong magnetic field B applied normal...... to the sample layers. While varying B, the intensities of the PLE peaks have been measured as functions of energy separation Delta E between excited ME peaks and the ground state of the system. The resonance profiles have been found to have maxima at Delta E-max close to the energy of the GaAs LO phonon...

Pu-erh Tea Inhibits Tumor Cell Growth by Down-Regulating Mutant p53

Science.gov (United States)

Zhao, Lanjun; Jia, Shuting; Tang, Wenru; Sheng, Jun; Luo, Ying

2011-01-01

Pu-erh tea is a kind of fermented tea with the incorporation of microorganisms’ metabolites. Unlike green tea, the chemical characteristics and bioactivities of Pu-erh tea are still not well understood. Using water extracts of Pu-erh tea, we analyzed the tumor cell growth inhibition activities on several genetically engineered mouse tumor cell lines. We found that at the concentration that did not affect wild type mouse embryo fibroblasts (MEFs) growth, Pu-erh tea extracts could inhibit tumor cell growth by down-regulated S phase and cause G1 or G2 arrest. Further study showed that Pu-erh tea extracts down-regulated the expression of mutant p53 in tumor cells at the protein level as well as mRNA level. The same concentration of Pu-erh tea solution did not cause p53 stabilization or activation of its downstream pathways in wild type cells. We also found that Pu-erh tea treatment could slightly down-regulate both HSP70 and HSP90 protein levels in tumor cells. These data revealed the action of Pu-erh tea on tumor cells and provided the possible mechanism for Pu-erh tea action, which explained its selectivity in inhibiting tumor cells without affecting wild type cells. Our data sheds light on the application of Pu-erh tea as an anti-tumor agent with low side effects. PMID:22174618

Fast and Simultaneous Determination of Pu(Ⅳ) and Nitric Acid in Spent Nuclear Fuel Reprocessing Sample by Near Infrared Spectroscopy

Institute of Scientific and Technical Information of China (English)

LI; Ding-ming; ZHANG; Li-hua; WANG; Ling; GONG; Yan-ping; FAN; De-jun; YI; Bao-shan; CHEN; Qiang; JI; Yong-chao; WU; Ji-zong

2013-01-01

Determination of Pu(Ⅳ)and nitric acid plays significant role in nuclear fuel reprocessing plant to control process accurately and timely.Coupling C-T fixed-type grating with InGaAs detector,a new novel analytical system for simultaneous measurement of nitric acid and Pu(Ⅳ)was developed by our working group.After obtaining near infrared absorptive spectra by the spectroscopic instrument,the spectra data

Gallium Content in PuO2 Using Laser Induced Breakdown Spectroscopy (LIBS)

International Nuclear Information System (INIS)

Smith, C.A.; Martinez, M.A.; Veirs, D.K.

1999-01-01

Laser Induced Breakdown Spectroscopy (LIBS) has been applied to the semi-quantitative analysis of gallium in plutonium oxide at the Los Alamos Plutonium Facility. The oxide samples were generated by the Thermally Induced Gallium Removal (TIGR) process, a pretreatment step prior to MOX fuel processing. The TIGR process uses PuO 2 containing 1 wt% gallium (nominal) as feed material. Following the TIGR process, gallium content was analyzed by LIBS and also by conventional wet chemical analysis (ICP-MS). Although the data range was insufficient to obtain an adequate calibration, general agreement between the two techniques was good. LIBS was found to have a useful analytical range of 34-400 ppm for Ga in PuO 2

Analysis of plutonium isotope ratios including 238Pu/239Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS.

Science.gov (United States)

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

2017-04-01

Isotope ratio analysis of individual uranium-plutonium (U-Pu) mixed oxide particles contained within environmental samples taken from nuclear facilities is proving to be increasingly important in the field of nuclear safeguards. However, isobaric interferences, such as 238 U with 238 Pu and 241 Am with 241 Pu, make it difficult to determine plutonium isotope ratios in mass spectrometric measurements. In the present study, the isotope ratios of 238 Pu/ 239 Pu, 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of plutonium with UTEVA resins. Furthermore, 238 Pu/ 239 Pu isotope ratios were able to be calculated by using both the 238 Pu/( 239 Pu+ 240 Pu) activity ratios that had been measured through alpha spectrometry and the 240 Pu/ 239 Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including 238 Pu/ 239 Pu, in individual U-Pu mixed oxide particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Smilansky-Solomyak model with a delta '-interaction

Czech Academy of Sciences Publication Activity Database

Exner, Pavel; Lipovský, J.

2018-01-01

Roč. 382, č. 18 (2018), s. 1207-1213 ISSN 0375-9601 R&D Projects: GA ČR GA17-01706S Institutional support: RVO:61389005 Keywords : Smilansky-Solomyak model * delta '-interaction * spectral theory Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics ( physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 1.772, year: 2016

Study of U - Pu - Fe alloys (Masurca critical experiment); Etudes d'alliages U-Pu-Fe (experience critique MASURCA)

Energy Technology Data Exchange (ETDEWEB)

Barthelemy, P; Boucher, R [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1965-07-01

Three compositions have been studied: 73.5 U - 25 Pu - 1.5 Fe (weight %) 74 U - 25 Pu - 1 Fe 74.5 U - 25 Pu - 0.5 Fe Elaboration and Casting are easy. After two weeks in air 74.5 U - 25 Pu - 0.5 Fe alloys are reduced in powder. As-cast alloys containing 1 and 1,5% Fe are kept undamaged during several months. A rapid oxidisation of the alloys is however observed when the samples undergo the phase transformation (at 595 deg. C and 590 deg. C respectively). Ignition tests in the presence of air show that the oxidisation starts at about 250 deg. C and that the reaction does not spread. Ignition is not observed during heating from 20 to 660 deg. C. The transformation temperature, the melting temperature and the thermal expansion coefficients have been determined by dilatometry. Below the transformation temperature, the principal phases are U-Pu zeta and (U, Pu){sub 6}Fe. Thermal conductibility, Young modulus, density and heat of fusion have been measured. Compatibility tests show that between U-Pu-Fe and stainless steel a phase of (U, Pu){sub 6}Fe type is formed. The 74 U - 25 Pu - 1% Fe alloy seems to behave better than 73.5 U - 25 Pu - 1.5% Fe alloy because the (U, Pu){sub 6}Fe layer is two or three times smaller. Finally, the thermal stability has been studied with the 74 U - 25 Pu - 1% Fe alloy. A dilatometric anomaly (very weak expansion) occurs when the sample is heated above transformation temperature and cooled. But there is no anomaly by thermal cycling from 50 deg. C to 400 deg. C and there is no deterioration of alloys by heat treatments at 100 deg. C, 200 deg. C, 300 deg. C during 5 months under vacuum. (authors) [French] Trois compositions ont ete etudiees: 73,5 U - 25 Pu - 1,5 Fe (% ponderaux) 74 U - 25 Pu - 1 Fe 74,5 U - 25 Pu - 0,5 Fe Les elaborations et mises en forme sont-faciles. Les alliages a 0,5% de fer tombent en poudre apres 15 jours d'exposition a l'air. Les alliages a 1 et 1,5% de fer, bruts de coulee, se conservent plusieurs mois. Cependant

Iodine-stabilized single-frequency green InGaN diode laser.

Science.gov (United States)

Chen, Yi-Hsi; Lin, Wei-Chen; Shy, Jow-Tsong; Chui, Hsiang-Chen

2018-01-01

A 520-nm InGaN diode laser can emit a milliwatt-level, single-frequency laser beam when the applied current slightly exceeds the lasing threshold. The laser frequency was less sensitive to diode temperature and could be finely tuned by adjusting the applied current. Laser frequency was stabilized onto a hyperfine component in an iodine transition through the saturated absorption spectroscopy. The uncertainty of frequency stabilization was approximately 8×10 -9 at a 10-s integration time. This compact laser system can replace the conventional green diode-pumped solid-state laser and applied as a frequency reference. A single longitudinal mode operational region with diode temperature, current, and output power was investigated.

Stability of Cu(In,Ga)Se2 solar cells: A literature review

NARCIS (Netherlands)

Theelen, M.; Daume, F.

2016-01-01

As Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) technology matures to production on an industrial scale, its long-term stability becomes increasingly important: The electric yield and thus the revenue of a PV system depend on both the initial conversion efficiency as well as its development over time.

Role of Ag-alloy in the thermal stability of Ag-based ohmic contact to GaN(0 0 0 1) surface

International Nuclear Information System (INIS)

Xiong, Zhihua; Qin, Zhenzhen; Zhao, Qian; Chen, Lanli

2015-01-01

First-principles calculations are performed to study Ag and Ag-alloy adsorption stability on GaN(0 0 0 1) surface. We find Ag only contact to GaN surface is unstable under high temperature. While Ag-alloy adsorption exhibits better adsorption stability and electronic properties than that of the Ag only contact,due to the enhanced interaction between Ag-alloy and GaN(0 0 0 1) surface. The Ag-alloy, particularly AgNi, is proposed to be used as very promising ohmic contact to GaN for practical applications

Current linearity and operation stability in Al2O3-gate AlGaN/GaN MOS high electron mobility transistors

Science.gov (United States)

Nishiguchi, Kenya; Kaneki, Syota; Ozaki, Shiro; Hashizume, Tamotsu

2017-10-01

To investigate current linearity and operation stability of metal-oxide-semiconductor (MOS) AlGaN/GaN high electron mobility transistors (HEMTs), we have fabricated and characterized the Al2O3-gate MOS-HEMTs without and with a bias annealing in air at 300 °C. Compared with the as-fabricated (unannealed) MOS HEMTs, the bias-annealed devices showed improved linearity of I D-V G curves even in the forward bias regime, resulting in increased maximum drain current. Lower subthreshold slope was also observed after bias annealing. From the precise capacitance-voltage analysis on a MOS diode fabricated on the AlGaN/GaN heterostructure, it was found that the bias annealing effectively reduced the state density at the Al2O3/AlGaN interface. This led to efficient modulation of the AlGaN surface potential close to the conduction band edge, resulting in good gate control of two-dimensional electron gas density even at forward bias. In addition, the bias-annealed MOS HEMT showed small threshold voltage shift after applying forward bias stress and stable operation even at high temperatures.

Stability constants important to the understanding of plutonium in environmental waters, hydroxy and carbonate complexation of PuO2+

International Nuclear Information System (INIS)

Bennett, D.A.; Lawrence Berkeley Lab., CA

1990-01-01

The formation constants for the reactions PuO 2 + + H 2 O = PuO 2 (OH) + H + and PuO 2 + + CO 3 2 = PuO 2 (CO 3 ) - were determined in aqueous sodium perchlorate solutions by laser-induced photoacoustic spectroscopy. The molar absorptivity of the PuO 2 + band at 569 nm decreased with increasing hydroxide concentration. Similarly, spectral changes occurred between 540 and 580 nm as the carbonate concentration was increased. The absorption data were analyzed by the non-linear least-squares program SQUAD to yield complexation constants. Using the specific ion interaction theory, both complexation constants were extrapolated to zero ionic strength. These thermodynamic complexation constants were combined with the oxidation-reduction potentials of Pu to obtain Eh versus pH diagrams. 120 refs., 35 figs., 12 tabs

Migration behaviour of Pu released from Pu-doped glass in compacted bentonite

International Nuclear Information System (INIS)

Ashida, T.; Kohara, Y.; Yui, M.

1994-01-01

In order to investigate the coupled behavior of Pu release from the waste glass and transport in bentonite, a migration experiment with compacted sodium-type bentonite saturated with distilled water was carried out at room temperature, in which Pu-doped borosilicate glass was sandwiched. Under these conditions, leaching of Pu from the glass, diffusion and sorption of Pu in the compacted bentonite occur simultaneously. (orig.)

Solubility of reactor fuels in the mouse lung with respect to their U/Pu and 238Pu/239Pu ratios

International Nuclear Information System (INIS)

Talbot, R.J.; Baker, S.T.

1989-01-01

The studies reported were designed to assess the comparative in vivo solubilities of a range of plutonium containing reactor fuels. To simulate these fuels, mixed U/Pu oxides were prepared and calcined at 1600 0 C. A plutonium content of 3% w/w was chosen as typical of water-cooled reactor fuel. Higher concentrations of plutonium (10, 20 and 30%) were included to simulate fast reactor fuel. As it is known that 238 PuO 2 , with high specific activity, is translocated more rapidly from lung than 239 PuO 2 , the effect of isotopic composition of plutonium in simulated reactor fuels was also investigated. For this purpose, both the water-cooled and fast-reactor fuels were prepared with plutonium containing 2% of 238 Pu by weight. The resulting oxides had about 6 times the specific activity of those prepared with 239 Pu. Groups of mice were killed at 1, 3, 6, 12 and 18 months after inhaling aerosols of the simulated reactor fuels. After 3 months, measurements of Pu retention in the lung showed no marked differences between materials. After 6 months, measurements of plutonium deposited in the liver and skeleton showed that mixed U/Pu oxides were more soluble in vivo than 239 PuO 2 . Their solubility was inversely related to their plutonium content. The addition of 238 Pu to the plutonium resulted in enhanced translocation of plutonium from the lung, in the cases of water-cooled reactor fuel by a factor of two. (author)

Raman spectrometric determination of Pu(VI) and Pu(V) in nitric acid solutions

International Nuclear Information System (INIS)

Gantner, E.; Freudenberger, M.; Steinert, D.; Ache, H.J.

1987-03-01

The determination of Pu(VI) in nitric acid solutions by spontaneous Laser Raman Spectrometry (LRS) was investigated and a calibration curve was established using U(VI) as internal standard. In addition, the concentrations of Pu(VI) and Pu(V) as a function of time were measured by this method in Pu(VI) solutions of different acidity containing H 2 O 2 as the reducing agent. In solutions which are intensely coloured by the presence of Ru(NO) complexes Pu(VI) can also be determined by LRS using a Kr + laser as excitation source. In future experiments, the study of the Pu(IV)-interaction with Ru using LRS and spectrophotometry as analytical techniques is therefore intended. (orig.) [de

Isotope ratios of 240Pu/239Pu in soil samples from different areas

International Nuclear Information System (INIS)

Muramatsu, Yasuyuki; Yoshida, Satoshi; Yamazaki, Shinnosuke

2003-01-01

Plutonium concentrations and 240 Pu/ 239 Pu atom ratios in soil samples from Japan and other areas in the world (including IAEA standard reference materials) were determined by ICP-MS. The range of 240 Pu/ 239 Pu atom ratios observed in 21 Japanese soil samples was 0.155 - 0.194 and the average was 0.180 ± 0.011, which is comparable to the global fallout value. A low ratio of about 0.05, which is derived from Pu-bomb, was found in samples from Nishiyama (Nagasaki) and Mururoa Atoll (IAEA-368), while a high ratio of about 0.31 was found in a sample from Bikini Atoll (Marshall Islands). The ratio for Irish Sea sediment (IAEA-135) was 0.21, which was higher than the global fallout value, suggesting the influence by the contamination from the Sellafield facility. The 240 Pu/ 239 Pu atom ratios in soils from the Chernobyl area were determined, and the ratio was found to be very high (about 0.4), indicating the high burn-up grade of the reactor fuel. These results show that the 240 Pu/ 239 Pu ratio can be used as a finger print to identify the source of the contamination. (author)

Direct fabrication of 238PuO2 fuel forms

International Nuclear Information System (INIS)

Burney, G.A.; Congdon, J.W.

1982-07-01

The current process for the fabrication of 238 PuO 2 heat sources includes precipitation of small particle plutonium oxalate crystals (4 to 6 μm diameter), a calcination to PuO 2 , ball milling, cold pressing, granulation (60 to 125 μm), and granule sintering prior to hot pressing the fuel pellet. A new two-step direct-strike Pu(III) oxalate precipitation method which yields mainly large well-developed rosettes (50 to 100 μm diameter) has been demonstrated in the laboratory and in the plant. These large rosettes are formed by agglomeration of small (2 to 4 μm) crystals, and after calcining and sintering, were directly hot pressed into fuel forms, thus eliminating several of the powder conditioning steps. Conditions for direct hot pressing of the large heat-treated rosettes were determined and a full-scale General Purpose Heat Source pellet was fabricated. The pellet had the desired granule-type microstructure to provide dimensional stability at high temperature. 27 figures

Comparison of the stability of Y-90-, Lu-177- and Ga-68- labeled human serum albumin microspheres (DOTA-HSAM)

Energy Technology Data Exchange (ETDEWEB)

Wunderlich, Gerd [Department of Nuclear Medicine, University Hospital, 01307 Dresden (Germany); Schiller, Eik, E-mail: eisc@rotop-pharmaka.d [ROTOP Pharmaka AG, 01454 Radeberg (Germany); Bergmann, Ralf; Pietzsch, Hans-Juergen [Forschungszentrum Dresden-Rossendorf, Institute of Radiopharmacy, P.O. Box 510119, 01314 Dresden (Germany)

2010-11-15

Introduction: Microparticles derived from denatured human serum albumin (DOTA-derivatized human serum albumin microspheres, or DOTA-HSAM) are attractive carriers of radionuclides for both therapeutic and diagnostic purposes. In this article, we describe a labeling procedure for diagnostic (Ga-68) and therapeutic (Y-90, Lu-177) radionuclides and report on the results of stability studies of these products. Methods: DOTA-HSAM was labeled in 0.5 M ammonium acetate buffer, pH 5.0, containing 0.02 mg/ml detergent. After adding the radionuclide, the mixture was shaken for 15 min at 90{sup o}C. Labeling yields and in vitro stability were determined by thin-layer chromatography. For determination of the in vivo stability of Ga-68 and Y-90 DOTA-HSAM, the particles were injected intravenously in Wistar rats. Results: Labeling yields up to 95% in the case of Ga-68 and Lu-177 were achieved. Ga-68-labeled DOTA-HSAM showed high in vitro and in vivo stability. The amount of particle-bound radioactivity of Lu-177 DOTA-HSAM declines slowly in a linear manner to approximately 72% after 13 days. For Y-90, the labeling yield decreased with increasing radioactivity level. We presume radiolysis as the reason for these findings. Conclusion: The labeling of DOTA-HSAM with different radionuclides is easy to perform. The radiation-induced cleavage of the labeled chelator together with the rather short half-life of radioactivity fixation in vivo (3.7 days) is, in our opinion, opposed to therapeutic applications of DOTA-HSAM. On the other hand, the high stability of Ga-68 DOTA-HSAM makes them an attractive candidate for the measurement of regional perfusion by PET.

Comparison of the stability of Y-90-, Lu-177- and Ga-68- labeled human serum albumin microspheres (DOTA-HSAM)

International Nuclear Information System (INIS)

Wunderlich, Gerd; Schiller, Eik; Bergmann, Ralf; Pietzsch, Hans-Juergen

2010-01-01

Introduction: Microparticles derived from denatured human serum albumin (DOTA-derivatized human serum albumin microspheres, or DOTA-HSAM) are attractive carriers of radionuclides for both therapeutic and diagnostic purposes. In this article, we describe a labeling procedure for diagnostic (Ga-68) and therapeutic (Y-90, Lu-177) radionuclides and report on the results of stability studies of these products. Methods: DOTA-HSAM was labeled in 0.5 M ammonium acetate buffer, pH 5.0, containing 0.02 mg/ml detergent. After adding the radionuclide, the mixture was shaken for 15 min at 90 o C. Labeling yields and in vitro stability were determined by thin-layer chromatography. For determination of the in vivo stability of Ga-68 and Y-90 DOTA-HSAM, the particles were injected intravenously in Wistar rats. Results: Labeling yields up to 95% in the case of Ga-68 and Lu-177 were achieved. Ga-68-labeled DOTA-HSAM showed high in vitro and in vivo stability. The amount of particle-bound radioactivity of Lu-177 DOTA-HSAM declines slowly in a linear manner to approximately 72% after 13 days. For Y-90, the labeling yield decreased with increasing radioactivity level. We presume radiolysis as the reason for these findings. Conclusion: The labeling of DOTA-HSAM with different radionuclides is easy to perform. The radiation-induced cleavage of the labeled chelator together with the rather short half-life of radioactivity fixation in vivo (3.7 days) is, in our opinion, opposed to therapeutic applications of DOTA-HSAM. On the other hand, the high stability of Ga-68 DOTA-HSAM makes them an attractive candidate for the measurement of regional perfusion by PET.

Electrical conductivity of cobalt doped La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}}

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Wu, Lingli; Liang, Ying [Department of Chemistry, Xiamen University, Xiamen 361005, Fujian (China)

2007-03-30

La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM8282), La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3-{delta}} (LSGMC5) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10{sup -5} atm) and low oxygen partial pressure regions (<10{sup -15} atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, P{sub O{sub 2}} dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about -1/4, and P{sub O{sub 2}} dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number. (author)

Spectral asymptotics of a strong delta ' interaction supported by a surface

Czech Academy of Sciences Publication Activity Database

Exner, Pavel; Jex, M.

2014-01-01

Roč. 378, 30-31 (2014), s. 2091-2095 ISSN 0375-9601 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : delta ' surface interaction * strong coupling expansion Subject RIV: BE - Theoretical Physics Impact factor: 1.683, year: 2014

Quantitative Assay of Pu-239 and Pu-240 by Neutron Transmission Measurements

Energy Technology Data Exchange (ETDEWEB)

Johansson, E

1971-04-15

A method for quantitative assay of 239Pu and 240Pu has been tested at the reactor R1 in Stockholm. The method makes use of a fast chopper to measure the neutron transmission through a sample around the main resonances of these two isotopes - at 0.296 eV in 239Pu and at 1.056 eV in 240Pu. The transmission data measured are then combined with the known resonance cross sections to give the content of the isotopes. The method is nondestructive, i.e., one can use fuel pins as samples, even highly irradiated ones. A time-of-flight spectrometer of moderate capacity, like our fast chopper, is sufficient as the resonances are located at low energy. Altogether five samples have been used in the tests of the method. The results have been compared with mass spectrometer values. This comparison came out quite well for 239Pu whereas the chopper results for 240Pu were more than 10 per cent higher than the mass spectrometer results. This large deviation might be due to errors in the resonance cross section for 240Pu used in the analysis of the transmission data from the chopper. The best possible accuracy for a 15-hour run with our equipment is +- 1 per cent for 239Pu and +- 2 per cent for 240Pu, obtained for thick samples - about 3 x 1020 atoms per cm2 for each isotope. The accuracy corresponds to 68 per cent confidence level and does not include any contribution from the uncertainty in the resonance cross section

Roles of POLD4, smallest subunit of DNA polymerase {delta}, in nuclear structures and genomic stability of human cells

Energy Technology Data Exchange (ETDEWEB)

Huang, Qin Miao [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Akashi, Tomohiro [Division of Molecular Mycology and Medicine, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Masuda, Yuji; Kamiya, Kenji [Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553 (Japan); Takahashi, Takashi [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Suzuki, Motoshi, E-mail: msuzuki@med.nagoya-u.ac.jp [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan)

2010-01-01

Mammalian DNA polymerase {delta} (pol {delta}) is essential for DNA replication, though the functions of this smallest subunit of POLD4 have been elusive. We investigated pol {delta} activities in vitro and found that it was less active in the absence of POLD4, irrespective of the presence of the accessory protein PCNA. shRNA-mediated reduction of POLD4 resulted in a marked decrease in colony formation activity by Calu6, ACC-LC-319, and PC-10 cells. We also found that POLD4 reduction was associated with an increased population of karyomere-like cells, which may be an indication of DNA replication stress and/or DNA damage. The karyomere-like cells retained an ability to progress through the cell cycle, suggesting that POLD4 reduction induces modest genomic instability, while allowing cells to grow until DNA damage reaches an intolerant level. Our results indicate that POLD4 is required for the in vitro pol {delta} activity, and that it functions in cell proliferation and maintenance of genomic stability of human cells.

Determination of {sup 240}Pu/{sup 239}Pu ratio and its significance in environmental studies

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, Yasuyuki [National Inst. of Radiological Sciences, Chiba (Japan)

1999-03-01

Analytical procedures for the determination of Pu concentrations and its isotopic ratios in environmental samples were developed by using ICP-MS. Detection limit of Pu by ICP-MS was about 0.02 pg ml{sup -1} (0.05 mBq ml{sup -1} for {sup 239}Pu; 0.17 mBq ml{sup -1} for {sup 240}Pu) in the sample solution. Analytical results of {sup 239+240}Pu in IAEA standard reference materials indicated that the accuracy of this method was satisfactory. Data on the {sup 240}Pu/{sup 239}Pu atom ratios, which are rare in the literature, were also obtained for soil and sediment samples (including IAEA standard reference materials) from different areas such as Irish Sea, Mururoa Atoll, Marshall Islands, Chernobyl, Kyshtym, Nagasaki and some other places in Japan. The range of the {sup 240}Pu/{sup 239}Pu ratios was about 0.04-0.4, and the ratios are depending on the origin of the materials. Analytical results for the {sup 240}Pu/{sup 239}Pu atom ratios provide information about the source of the contamination and the transfer of plutonium in the environment. (author)

Stability of field emission current from porous n-GaAs(110)

Science.gov (United States)

Tondare, V. N.; Naddaf, M.; Bhise, A. B.; Bhoraskar, S. V.; Joag, D. S.; Mandale, A. B.; Sainkar, S. R.

2002-02-01

Field electron emission from porous GaAs has been investigated. The emitter was prepared by anodic etching of n-GaAs (110) in 0.1 M HCl solution. The as-etched porous GaAs shows nonlinear Fowler-Nordheim (FN) characteristics, with a low onset voltage. The emitter, after operating for 6 h at the residual gas pressure of 1×10-8 mbar, shows a linear FN characteristics with a relatively high onset voltage and poor field emission current stability as compared to the as-etched emitter. The change in the behavior was attributed to the residual gas ion bombardment during field electron emission. X-ray photoelectron spectroscopic investigations were carried out on as-etched sample and the one which was studied for field emission. The studies indicate that the as-etched surface contains As2O3 and the surface after field electron emission for about 6 h becomes gallium rich. The presence of As2O3 seems to be a desirable feature for the stable field emission current.

Simultaneous measurement of 239Pu, 240Pu, 241Pu, and 242Pu by high resolution inductively coupled plasma mass spectrometer (HR ICP-MS) in marine sediments

International Nuclear Information System (INIS)

Bruneau, F.

1999-01-01

Transuranics elements are of particular interest in radioecological studies because of their radiotoxicity and their potential use to decipher source fingerprints and transport processes. The simultaneous measurement of 239 Pu, 240 Pu, 241 Pu, and 242 Pu in environmental samples requires a specific chemical procedure. This work deals with an analytical procedure which yields a very high grade of purification of Pu suitable for ultra low level detection by HR ICP-MS, from marine sediments. After the elimination of major elements (Fe, Al, Mg...) by a first chromatographic separation, a new device of purification by solvent extraction and concentration by a second chromatographic separation is used to obtain a concentrated and high purified solution of plutonium. The chemical procedure have been validated on IAEA certified sediment samples and on sediment samples collected in the roads of Cherbourg which had been previously analysed by other techniques (a spectrometry and thermo-ionisation mass spectrometer). (author)

Effects of the composition of sputtering target on the stability of InGaZnO thin film transistor

International Nuclear Information System (INIS)

Huh, Jun-Young; Jeon, Jae-Hong; Choe, Hee-Hwan; Lee, Kang-Woong; Seo, Jong-Huyn; Ryu, Min-Ki; Park, Sang-Hee Ko; Hwang, Chi-Sun; Cheong, Woo-Seok

2011-01-01

In this study, we investigated the electrical characteristics and the stability of amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) from the viewpoint of active layer composition. Active layers of TFTs were deposited by r.f. sputtering. Two kinds of sputtering targets, which have different compositional ratios of In:Ga:Zn, were used to make variations in the active layer composition. All the fabricated IGZO TFTs showed more excellent characteristics than conventional amorphous silicon TFTs. However, in accordance with the Ga content, IGZO TFTs showed somewhat different electrical characteristics in values such as the threshold voltage and the field effect mobility. The device stability was also dependent on the Ga content, but had trade-off relation with the electrical characteristics.

Stability and diffusion of interstitital and substitutional Mn in GaAs of different doping types

CERN Document Server

Pereira, LMC; Decoster, S; Correia, JG; Amorim, LM; da Silva, MR; Araújo, JP; Vantomme, A

2012-01-01

We report on the lattice location of Mn impurities (< 0.05%) in undoped (semi-insulating) and heavily $n$-type doped GaAs, by means of $\\beta^{-}$-emission channeling from the decay of $^{56}$Mn produced at ISOLDE/CERN. In addition to the majority substituting for Ga, we locate up to 30% of the Mn impurites on tetrahedral interstitial sites with As nearest neighbors. In line with the recently reported high thermal stability of interstitial Mn in heavily $p$-type doped GaAs [L. M. C. Pereira et al., Appl. Phys. Lett. 98, 201905 (2011)], the interstitial fraction is found to be stable up to 400$^{\\circ}$C, with an activation energy for diffusion of 1.7–2.3 eV. By varying the concentration of potentially trapping defects, without a measurable effect on the migration energy of the interstitial impurities, we conclude that the observed high thermal stability is characteristic of isolated interstitial Mn. Being difficult to reconcile with the general belief that interstitial Mn is the donor defect that out-dif...

Deep levels in as-grown and Si-implanted In(0.2)Ga(0.8)As-GaAs strained-layer superlattice optical guiding structures

Science.gov (United States)

Dhar, S.; Das, U.; Bhattacharya, P. K.

1986-01-01

Trap levels in about 2-micron In(0.2)Ga(0.8)As(94 A)/GaAs(25 A) strained-layer superlattices, suitable for optical waveguides, have been identified and characterized by deep-level transient spectroscopy and optical deep-level transient spectroscopy measurements. Several dominant electron and hole traps with concentrations of approximately 10 to the 14th/cu cm, and thermal ionization energies Delta-E(T) varying from 0.20 to 0.75 eV have been detected. Except for a 0.20-eV electron trap, which might be present in the In(0.2)Ga(0.8)As well regions, all the other traps have characteristics similar to those identified in molecular-beam epitaxial GaAs. Of these, a 0.42-eV hole trap is believed to originate from Cu impurities, and the others are probably related to native defects. Upon Si implantation and halogen lamp annealing, new deep centers are created. These are electron traps with Delta-E(T) = 0.81 eV and hole traps with Delta-E(T) = 0.46 eV. Traps occurring at room temperature may present limitations for optical devices.

Fabrication of 238Pu based sources for energy micro-generator

International Nuclear Information System (INIS)

Barthelemy, Pierre; Boucher, Rene

1969-04-01

The authors describe the fabrication of sources of 238 Pu. The plutonium-scandium alloy is obtained by arc fusion in its delta phase. This alloy is chosen for its excellent malleability, and is rolled at 20 C. Pellets are then cut and decontaminated. Each pellet is then placed in a first tantalum sheath which is welded by electronic bombardment. A second sheath in platinum-iridium is placed around the first one, and also welded by using the same welding process. The so-fabricated sources are to feed energy thermal-electric conversion micro-generators which are supposed to operate tens of years in medical applications as organ stimulators [fr

Análisis autosimilar de pozos cuánticos cuasirregulares delta dopados tipo n en GaAs

Directory of Open Access Journals (Sweden)

Heraclio García-Cervantes

2014-01-01

Full Text Available Se estudia la esctructura electrónica de pozos cuánticos delta dopados tipo n en GaAs, en el cual el sistema de multiples pozos es construido de acuerdo a la secuencia de Fibonacci. Los bloques A y B corresponden a pozos delta dopados con una densidad de impurezas n2DA y n2DB, y el mismo ancho de los pozos. La aproximación de Thomas-Fermi, el modesemi-empírico de enlace fuerte (tight-binding sp3s* incluyendo el espín, el modelo de empalme de la función de Green y la matriz de transferencia fueron implementados para obtener el potencial de confinamiento, la estructura electrónica y la autosimilaridad del espectro. La fragmentación del espectro electrónico se presenta cada vez que los bloques A y B interaccionan, y aumenta a medida que la diferencia de impurezas entre A y B aumenta. La función de onda del primer estado de las bandas fragmentadas presenta características críticas, esto es, no es un estado localizado ni extendido, presenta características de autosimilaridad. Por lo tanto, las características cuasiregulares se conservan independientemente de la complejidad del sistema y pueden afectar el funcionamiento de los dispositivos basados a estas estructuras.

Recovery of 238PuO2 by Molten Salt Oxidation Processing of 238PuO2 Contaminated Combustibles (Part II)

Science.gov (United States)

Remerowski, Mary Lynn; Dozhier, C.; Krenek, K.; VanPelt, C. E.; Reimus, M. A.; Spengler, D.; Matonic, J.; Garcia, L.; Rios, E.; Sandoval, F.; Herman, D.; Hart, R.; Ewing, B.; Lovato, M.; Romero, J. P.

2005-02-01

Pu-238 heat sources are used to fuel radioisotope thermoelectric generators (RTG) used in space missions. The demand for this fuel is increasing, yet there are currently no domestic sources of this material. Much of the fuel is material reprocessed from other sources. One rich source of Pu-238 residual material is that from contaminated combustible materials, such as cheesecloth, ion exchange resins and plastics. From both waste minimization and production efficiency standpoints, the best solution is to recover this material. One way to accomplish separation of the organic component from these residues is a flameless oxidation process using molten salt as the matrix for the breakdown of the organic to carbon dioxide and water. The plutonium is retained in the salt, and can be recovered by dissolution of the carbonate salt in an aqueous solution, leaving the insoluble oxide behind. Further aqueous scrap recovery processing is used to purify the plutonium oxide. Recovery of the plutonium from contaminated combustibles achieves two important goals. First, it increases the inventory of Pu-238 available for heat source fabrication. Second, it is a significant waste minimization process. Because of its thermal activity (0.567 W per gram), combustibles must be packaged for disposition with much lower amounts of Pu-238 per drum than other waste types. Specifically, cheesecloth residues in the form of pyrolyzed ash (for stabilization) are being stored for eventual recovery of the plutonium.

Recovery of 238PuO2 by Molten Salt Oxidation Processing of 238PuO2 Contaminated Combustibles (Part II)

International Nuclear Information System (INIS)

Remerowski, Mary Lynn; Dozhier, C.; Krenek, K.; VanPelt, C. E.; Reimus, M. A.; Spengler, D.; Matonic, J.; Garcia, L.; Rios, E.; Sandoval, F.; Herman, D.; Hart, R.; Ewing, B.; Lovato, M.; Romero, J. P.

2005-01-01

Pu-238 heat sources are used to fuel radioisotope thermoelectric generators (RTG) used in space missions. The demand for this fuel is increasing, yet there are currently no domestic sources of this material. Much of the fuel is material reprocessed from other sources. One rich source of Pu-238 residual material is that from contaminated combustible materials, such as cheesecloth, ion exchange resins and plastics. From both waste minimization and production efficiency standpoints, the best solution is to recover this material. One way to accomplish separation of the organic component from these residues is a flameless oxidation process using molten salt as the matrix for the breakdown of the organic to carbon dioxide and water. The plutonium is retained in the salt, and can be recovered by dissolution of the carbonate salt in an aqueous solution, leaving the insoluble oxide behind. Further aqueous scrap recovery processing is used to purify the plutonium oxide. Recovery of the plutonium from contaminated combustibles achieves two important goals. First, it increases the inventory of Pu-238 available for heat source fabrication. Second, it is a significant waste minimization process. Because of its thermal activity (0.567 W per gram), combustibles must be packaged for disposition with much lower amounts of Pu-238 per drum than other waste types. Specifically, cheesecloth residues in the form of pyrolyzed ash (for stabilization) are being stored for eventual recovery of the plutonium

Phonon anharmonicity and Gruneisen parameters of alpha-plutonium

International Nuclear Information System (INIS)

Filanovich, A.N.; Povzner, A.A.

2015-01-01

A self-consistent thermodynamic model of alpha-phase of plutonium is constructed. The calculations of thermal and elastic properties of α-Pu, carried out within this model, demonstrate that anomalously strong temperature dependence of the bulk modulus and unusually high value of the coefficient of thermal expansion of α-Pu are caused by its strong lattice anharmonicity. The isothermal and isobaric Gruneisen parameters of α-Pu and δ-Pu Pu_0_._9_6Ga_0_._0_4 are calculated. It is shown that wide spread of the values of Gruneisen parameter of α-Pu, obtained previously from different experimental data, is explained by the dependence of Gruneisen parameter of α-Pu on temperature. - Highlights: • A self-consistent thermodynamic model of alpha-plutonium is developed. • Thermal and elastic properties of alpha-plutonium are calculated. • The reason of spread in the values of Gruneisen parameter of alpha-Pu is established. • Different types of phonon anharmonicity in alpha-Pu and delta-Pu are revealed.

Liquid chromatographic studies on the behaviour of Pu(III), Pu(IV) and Pu(VI) on a RP stationary phase in presence of α-hydroxyisobutyric acid as a chelating agent

Energy Technology Data Exchange (ETDEWEB)

Jaison, P.G.; Kumar, Pranaw; Telmore, Vijay M. [Bhabha Atomic Research Centre, Mumbai (India). Fuel Chemistry Division

2017-06-01

Since plutonium possesses multiple oxidation states which can coexist in solution, a method for the identification of these oxidation states is important to understand its chemical processes. Liquid chromatographic studies were carried out to compare the chromatographic behaviour of different oxidation states of Pu in presence of the eluent, α-hydroxyisobutyric acid (HIBA). The three oxidation states of Pu viz. Pu(III), Pu(IV) and Pu(VI) were separated under optimised conditions. It was seen that the presence of the complexing agent influences the equilibrium of Pu(III)/(IV) as well as Pu(IV)/(VI) systems. Pu(III) to Pu(IV) conversion was found to be enhanced by high pH and concentration of HIBA whereas a relatively low pH and high concentration of HIBA promotes the conversion of Pu(VI) to Pu(IV).

On eigenvalue asymptotics for strong delta-interactions supported by surfaces with boundaries

Czech Academy of Sciences Publication Activity Database

Dittrich, Jaroslav; Exner, Pavel; Kuhn, C.; Pankrashkin, K.

2016-01-01

Roč. 97, 1-2 (2016), s. 1-25 ISSN 0921-7134 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : singular Schrodinger operator * delta-interaction * strong coupling * eigenvalue Subject RIV: BE - Theoretical Physics Impact factor: 0.933, year: 2016

Lifetime improvement and beam stabilization by longitudinal phase modulation at the DELTA electron storage ring; Lebensdauerverbesserung und Strahlstabilisierung durch longitudinale Phasenmodulation am Elektronenspreicherring DELTA

Energy Technology Data Exchange (ETDEWEB)

Fuersch, Jonathan

2014-10-16

In DELTA especially at high beam currents often the occurence of an instability of a longitudinal oscillation mode is observed. In the framework of the present thesis first with different procedure the cause of the longitudinal oscillation mode, which is especially strongly excited at high beam currents, is searched for. Thereby connections between the occurrence of this mode and parameters from the region of the storage-ring high-frequency system is observed. It is shown by comparison of different procedures, simulation calculations, and experimental pre-examinations, that especially by a phase modulation of the storage-ring high frequency an essential improvement of especially the longitudinal beam stability and the beam lifetime can be reached. For the durable and reliable improvement of these beam properties in the framework of the present thesis a system for the longitudinal phase modulation of the after-acceleration voltage in the cavity resonator of the DELTA storage ring is concipated, developed, constructed, taken in operation, and tested. Finally the results aimed hereby are presented and discussed.

Evaluation of nuclear data of 244Pu and 237Pu

International Nuclear Information System (INIS)

Nakagawa, Tsuneo; Konshin, V.A.

1995-10-01

The evaluation of nuclear data for 244 Pu and 237 Pu was made in the neutron energy region from 10 -5 eV to 20 MeV. For the both nuclides, the total, elastic and inelastic scattering, fission, capture, (n,2n) and (n,3n) reaction cross sections were evaluated on the basis of theoretical calculation. The resonance parameters were given for 244 Pu. The angular and energy distributions of secondary neutrons were also estimated for the both nuclides. The results were compiled in the ENDF-5 format and will be adopted in JENDL Actinoid File. (author)

Approximation of Schrodinger operators with delta-interactions supported on hypersurfaces

Czech Academy of Sciences Publication Activity Database

Behrndt, J.; Exner, Pavel; Holzmann, M.; Lotoreichik, Vladimir

2017-01-01

Roč. 290, 8-9 (2017), s. 1215-1248 ISSN 0025-584X R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : Schrodinger operators * delta-interactions supported on hypersurfaces * approximation by scaled regular potentials * norm resolvent convergence * spectral convergence Subject RIV: BE - Theoretical Physics OBOR OECD: Pure mathematics Impact factor: 0.742, year: 2016

On the spectrum of narrow Neumann waveguide with periodically distributed delta ' traps

Czech Academy of Sciences Publication Activity Database

Exner, Pavel; Khrabustovskyi, A.

2015-01-01

Roč. 48, č. 31 (2015), s. 315301 ISSN 1751-8113 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : periodic waveguides * Schrodinger operators * delta ' interaction * spectrum * gaps * asymptotic analysis Subject RIV: BE - Theoretical Physics Impact factor: 1.933, year: 2015

Worldwide data on fluxes of 239,240Pu, 238Pu to the oceans

International Nuclear Information System (INIS)

Aarkrog, A.

1987-04-01

According to measurements (GEOSECS) the world's oceans contain approximately 16 PBq 239,240 Pu, of which one-fourth is in the Atlantic and three-fourths in the Pacific Ocean. The expected inventory (from nuclear weapons testing) in the world's oceans is 12 PBq 239,240 Pu including local fallout at the test sites. In the Irish Sea a local contamination of 0.3 PBq 239,240 Pu from the Sellafield reprocessing plant resides in the sediments. No other sources than fallout and reprocessing add significantly to the 239,240 Pu inventories in the oceans. The discrepancy between measurements and expectations are assumed to be due to an underestimate of the rainfall and dry fallout (seaspray) and thus of the Pu-deposition over the oceans, but may also to some degree be due to inadequate sampling

Present status and future plans of the study for preparation of Pu reference materials

International Nuclear Information System (INIS)

Sumi, Mika; Kageyama, Tomio; Suzuki, Toru

2007-01-01

All accountancy analysis at the Plutonium Fuel Development Center of JAEA is performed by isotope dilution mass spectrometry with well-characterized standard materials. Though Pu reference materials has been supplied from foreign country, importing those Pu materials is gradually becoming more difficult and may be almost impossible to import them in future. Thus, in order to establish the capability and expertise for the preparation of Pu reference materials, JAEA has started collaborative work with NBL who has high skills for preparing and supplying nuclear reference materials for long periods. One of the targets of this collaboration is preparation of standard material for IDMS (LSD spike). MOX powder which has been stored in JAEA was dissolved and Purified to obtain Pu solution. A small portion of the Purified solution was transported to NBL for analysis. LSD spike will be prepared from this Pu solution and then validation analysis and performance test including stability test will be performed with NBL and JAEA. This report presents status and future plans for the collaboration work. (author)

Redox reactions of Pu(IV) and Pu(III) in the presence of acetohydroxamic acid in HNO(3) solutions.

Science.gov (United States)

Tkac, Peter; Precek, Martin; Paulenova, Alena

2009-12-21

The reduction of Pu(IV) in the presence of acetohydroxamic acid (HAHA) was monitored by vis-NIR spectroscopy. All experiments were performed under low HAHA/Pu(IV) ratios, where only the Pu(IV)-monoacetohydroxamate complex and Pu uncomplexed with HAHA were present in relevant concentrations. Time dependent concentrations of all absorbing species were resolved using molar extinction coefficients for Pu(IV), Pu(III), and the Pu(AHA)(3+) complex by deconvolution of spectra. From fitting of the experimental data by rate equations integrated by a numeric method three reactions were proposed to describe a mechanism responsible for the reduction and oxidation of plutonium in the presence of HAHA and HNO(3). Decomposition of Pu(AHA)(3+) follows a second order reaction mechanism with respect to its own concentration and leads to the formation of Pu(III). At low HAHA concentrations, a two-electron reduction of uncomplexed Pu(IV) with HAHA also occurs. Formed Pu(III) is unstable and slowly reoxidizes back to Pu(IV), which, at the point when all HAHA is decomposed, can be catalyzed by the presence of nitrous acid.

Determination of 238Pu, 239+240Pu, 241Pu and 241Am in radioactive waste from IPEN reactor

International Nuclear Information System (INIS)

Geraldo, Bianca; Taddei, Maria Helena T.; Cheberle, Sandra M.; Ferreira, Marcelo T.

2011-01-01

Ion exchange resin is a common type of radioactive waste arising from treatment of coolant water of the main circuit of research and nuclear power reactors. This waste contains high concentrations of fission and activation products. The management of this waste includes its characterization in order to determine and quantify specific radionuclides including those known as difficult-to-measure radionuclides (RDM). The analysis of RDMs generally involves expensive and time-consuming complex radiochemical analysis for purification and separation of the radionuclides. The objective of this work is to show an easy methodology for quantifying plutonium and americium isotopes in spent ion exchange resin, used for purification of the cooling water of the IEA-R1 reactor located at the Nuclear and Energy Research Institute, IPEN-CNEN/SP. The resins were destroyed by acid digestion, followed by purification and separation of the Pu and Am isotopes with anionic and chromatographic resins. 238 Pu, 239 + 24 '0Pu, and 24 '1Am isotopes were analyzed in an alpha spectrometer equipped with surface barrier detectors. 241 Pu isotope was analyzed by liquid scintillation counting. Chemical recovery yield ranged from 73 to 98% for Pu and 77 to 98% for Am, demonstrating that the methodology is suitable for identification and quantification of the isotopes studied in spent resins. (author)

Delta Cell Hyperplasia in Adult Goto-Kakizaki (GK/MolTac) Diabetic Rats

Czech Academy of Sciences Publication Activity Database

Alán, Lukáš; Olejár, Tomáš; Cahová, M.; Zelenka, Jaroslav; Berková, Z.; Smětáková, M.; Saudek, F.; Matěj, R.; Ježek, Petr

2015-01-01

Roč. 2015, č. 2015 (2015), s. 385395 ISSN 2314-6745 R&D Projects: GA ČR(CZ) GA13-06666S Institutional support: RVO:67985823 Keywords : Goto Kakizaki rats * diabetes * delta cell hyperplasia * somatostatin * pancreatic polypeptide deficiency Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 2.431, year: 2015

Presence of plutonium isotopes, 239Pu and 240Pu, in soils from Chile

International Nuclear Information System (INIS)

Chamizo, E.; García-León, M.; Peruchena, J.I.; Cereceda, F.; Vidal, V.; Pinilla, E.; Miró, C.

2011-01-01

Plutonium is present in every environmental compartment, due to a variety of nuclear activities. The Southern Hemisphere has received about 20% of the global 239 Pu and 240 Pu environmental inventory, with an important contribution of the so-called tropospheric fallout from both the atmospheric nuclear tests performed in the French Polynesia and in Australia by France and United Kingdom, respectively. In this work we provide new data on the impact of these tests to South America through the study of 239 Pu and 240 Pu in soils from different areas of Northern, Central and Southern Chile. The obtained results point out to the presence of debris from the French tests in the 20–40° Southern latitude range, with 240 Pu/ 239 Pu atomic ratios quite heterogeneous and ranging from 0.02 to 0.23. They are significantly different from the expected one for the global fallout in the Southern Hemisphere for the 30–53°S latitude range (0.185 ± 0.047), but they follow the same trend as the reported values by the Department of Energy of United States for other points with similar latitudes. The 239+240 Pu activity inventories show as well a wider variability range in that latitude range, in agreement with the expected heterogeneity of the contamination.

Data Evaluation of Actinide Cross Sections: ²³⁸Pu, ²³⁷Pu, and ²³⁶Pu

Energy Technology Data Exchange (ETDEWEB)

Guaglioni, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jurgenson, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Descalle, M. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thompson, I. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ormand, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Escher, J. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mattoon, C. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beck, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Burke, J. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bailey, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-10-04

This report documents the recent evaluation of the ²³⁶Pu, ²³⁷Pu, and ²³⁸Pu cross section sets. Nuclear data evaluation is the fundamental interface that takes measured nuclear cross section data and turns them into a continuous curve that 1) is consistent with other measurements and nuclear reaction theory/models, and 2) is required by down-stream users. All experiments that generate nuclear data need to include an evaluation step for their data to be broadly useful to the end users.

Measurements of ultrafast dynamics in a superconductor, YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, and a semiconductor, GaSb

Energy Technology Data Exchange (ETDEWEB)

Smith, D.C

1998-07-01

Measurements of ultrafast dynamics in GaSb and YBa{sub 2}Cu{sub 3}O{sub 7-}{delta} (YBCO) have been made with 1 ps or better resolution using time-resolved optical spectroscopy; pump-probe transmission and reflection, and time-resolved Raman spectroscopy. The study of carrier dynamics in GaSb focuses on the scattering of electrons between the F and L conduction band valleys by zone-boundary phonons {gamma}-L scattering in bulk GaSb and a GaSb/AlSb multiple quantum well sample has been investigated in a series of room temperature degenerate pump-probe transmission experiments with near bandgap excitation. There is a clear difference in the dynamics between experiments where electrons excited in {gamma} can/cannot directly scatter to the L valleys. Ensemble Monte Carlo simulations are presented which are in good agreement with the experiments. The strength of {gamma}-L scattering is quantified using an intervalley deformation potential for a single 'effective' zone-boundary phonon (25meV). A deformation potential of 3.6{+-}0.4 eVA{sup -1} is consistent with both the bulk and quantum well results. The temperature dependence of the dynamics in bulk GaSb is also explored. Time-resolved Raman spectroscopy (E{sub laser}{approx}E{sub 0}+{delta}{sub 0}) has been used to study {gamma}-F scattering by measuring the dynamics of phonons emitted during intravalley scattering. All the measured non-equilibrium phonon populations have a component whose lifetime is greater the phonons anharmonic lifetime. This component is interpreted as following the return of electrons from L to {gamma}. Comparison of the results with the pump-probe experiments indicates that this return is slowed by blocking of {gamma} states. The study of YBCO consists of pump-probe transmission and reflection measurements of thin films and single crystals in both the normal and superconducting states. Measurements of dynamics have been made with a wide range of probe energies lower than in any

242Pu as tracer for simultaneous determination of 237Np and 239,240Pu in environmental samples

DEFF Research Database (Denmark)

Chen, Q.J.; Dahlgaard, H.; Nielsen, S.P.

2002-01-01

A procedure has been developed using Pu-242 as tracer for simultaneous determination of Np-237 and Pu-239,Pu-240 in environmental samples. The validity of the method has been demonstrated by ICPMS and alpha-spectroscopy for up to 10 gram soil and sediment, seawater up to 200 litres. The paper...... from Np and Pu) R-before/R-after = 1.004 +/- 3.3% (S.D n = 20) and 1 litre seawater R-before/R-after = 1.019+/-1.9% (S.D., n = 12). Results from the intercomparison samples LAEA-135, LAEA-381 and from environmental samples are presented....... describes a suitable chemical procedure for Np and Pu including a quantitative pre-concentration of neptunium and plutonium, preparation of Np4+ and Pu4+, NP(NO3)(6)(2-) and Pu(NO3)(6)(2-), The ratio of Np-237/Pu-242 (or Np-237/Pu-239) before and after the procedure has been determined using 10 g soil (free...

Stability of AlGaN/GaN heterostructures after hydrogen plasma treatment

Energy Technology Data Exchange (ETDEWEB)

Babchenko, O., E-mail: oleg.babchenko@savba.sk [Institute of Electrical Engineering SAV, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Dzuba, J.; Lalinský, T. [Institute of Electrical Engineering SAV, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Vojs, M. [Institute of Electronics and Photonics STU, Ilkovičova 3, 812 19 Bratislava (Slovakia); Vincze, A. [International Laser Centre, Ilkovičova 3, 841 04 Bratislava (Slovakia); Ižák, T. [Institute of Physics AS CR, v.v.i., Cukrovarnicka 10, 162 53 Prague (Czech Republic); Vanko, G. [Institute of Electrical Engineering SAV, Dúbravská cesta 9, 841 04 Bratislava (Slovakia)

2017-02-15

Highlights: • AlGaN/GaNheterostructures with electric contacts were treated by hydrogen plasma. • No surface degradation after treatment was detected by SEM. • Hydrogen plasma caused increasing of sheet resistance up to 3.5 times after 60 min. • Incorporation of hydrogen in AlGaN sub-surface region was observed by SIMS. • Electrical measurements indicate hydrogen induced Schottky barrier lowering. - Abstract: We report on the investigation of low temperature (300 °C) hydrogen plasma treatment influence on the AlGaN/GaN heterostructures. This issue was raised in the frame of study on processes related to hybrid integration of diamond with GaN-based devices. At the same time, the capabilities of thin SiN{sub x} covering were investigated. The samples were exposed to low pressure hydrogen plasma ignited in the linear plasma system at low temperature. We analyze the surface morphology of samples by scanning electron microscopy while microstructural changes down to AlGaN/GaN interface were studied using secondary ion mass spectrometry. The sheet resistance, monitored using circular transmission line measurements, increases more than 3.5 times after 60 min treatment. The basic transport properties of the fabricated circular high electron mobility transistors after H{sub 2} plasma treatment were analyzed. The sheet resistance increasing was attributed to the decrease of effective mobility. Whilst, the observed Schottky barrier lowering indicates necessity of gate contact protection.

Two-photon spin-polarization spectroscopy in silicon-doped GaAs.

Science.gov (United States)

Miah, M Idrish

2009-05-14

We generate spin-polarized electrons in bulk GaAs using circularly polarized two-photon pumping with excess photon energy (DeltaE) and detect them by probing the spin-dependent transmission of the sample. The spin polarization of conduction band electrons is measured and is found to be strongly dependent on DeltaE. The initial polarization, pumped with DeltaE=100 meV, at liquid helium temperature is estimated to be approximately 49.5%, which is very close to the theoretical value (50%) permitted by the optical selection rules governing transitions from heavy-hole and light-hole states to conduction band states in a bulk sample. However, the polarization pumped with larger DeltaE decreases rapidly because of the exciting carriers from the split-off band.

Determination of Pu in soil samples; Determinacion de Pu en muestras de suelo

Energy Technology Data Exchange (ETDEWEB)

Torres C, C. O.; Hernandez M, H.; Romero G, E. T. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Vega C, H. R., E-mail: carioli_32907@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2016-10-15

The irreversible consequences of accidents occurring in nuclear plants and in nuclear fuel reprocessing sites are mainly the distribution of different radionuclides in different matrices such as the soil. The distribution in the superficial soil is related to the internal and external exposure to the radiation of the affected population. The internal contamination with radionuclides such as Pu is of great relevance to the nuclear forensic science, where is important to know the chemical and isotopic compositions of nuclear materials. The objective of this work is to optimize the radiochemical separation of plutonium (Pu) from soil samples and to determine their concentration. The soil samples were prepared using acid digestion assisted by microwave; purification of Pu was carried out with AG1X8 resin using ion exchange chromatography. Pu isotopes were measured using ICP-SFMS. In order to reduce the interference due to the presence of {sup 238}UH {sup +} in the samples, a solvent removal system (Apex) was used. In addition, the limit of detection and quantification of Pu was determined. It was found that the recovery efficiency of Pu in soil samples ranges from 70 to 93%. (Author)

Design and experimental investigation of a decentralized GA-optimized neuro-fuzzy power system stabilizer

Energy Technology Data Exchange (ETDEWEB)

Talaat, Hossam E.A.; Abdennour, Adel; Al-Sulaiman, Abdulaziz A. [Electrical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421 (Saudi Arabia)

2010-09-15

The aim of this research is the design and implementation of a decentralized power system stabilizer (PSS) capable of performing well for a wide range of variations in system parameters and/or loading conditions. The framework of the design is based on Fuzzy Logic Control (FLC). In particular, the neuro-fuzzy control rules are derived from training three classical PSSs; each is tuned using GA so as to perform optimally at one operating point. The effectiveness and robustness of the designed stabilizer, after implementing it to the laboratory model, is investigated. The results of real-time implementation prove that the proposed PSS offers a superior performance in comparison with the conventional stabilizer. (author)

Oxidation behaviour of plutonium rich (U, Pu)C and (U, Pu)O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sali, S.K., E-mail: sksali@barc.gov.in [Fuel Chemistry Division (India); Kulkarni, N.K.; Phatak, Rohan [Fuel Chemistry Division (India); Agarwal, Renu [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2016-10-15

Oxidation behaviour of (U{sub 0.3}Pu{sub 0.7})C{sub 1.06} was investigated in air by heating samples up to 1073 K and 1273 K. Thermogravimetry (TG) of the samples and X-ray powder diffraction (XRD) of the intermediate products were used to understand the phenomenon taking place during this process. Theoretical calculations were carried out to understand the multiple phase changes taking place during oxidation of carbide. Theoretical results were validated by XRD analysis of the products obtained at different stages of oxidation. The final oxidized products were found to be a single FCC phase with O/M = 2.15 (M = U + Pu). Oxidation kinetic studies of (U{sub 0.3}Pu{sub 0.7})O{sub 2} and (U{sub 0.47}Pu{sub 0.53})O{sub 2} were carried out in dry air, using thermogravimetry, under non-isothermal conditions. The activation energy of oxidation was found to be 49 and 70 kJ/mol, respectively. Lattice parameter dependence on Pu/M and O/M of plutonium rich mixed oxide (MOX) was established using combined results of XRD and TG analysis of (U{sub 0.3}Pu{sub 0.7})O{sub 2+x} and (U{sub 0.47}Pu{sub 0.53})O{sub 2+x}.

The Effect of the number of InGaN/GaN pairs on the photoelectrochemical properties of InGaN/GaN multi quantum wells

Energy Technology Data Exchange (ETDEWEB)

Bae, Hyojung; Park, Jun-Beom [Optoelectronics Convergence Research Center, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186 (Korea, Republic of); Fujii, Katsushi [Institute of Environmental Science and Technology, The University of Kitakyushu, Kitakyushu, Fukuoka (Japan); Lee, Hyo-Jong [Materials Science and Engineering, Dong-A University, Busan 49315 (Korea, Republic of); Lee, Sang-Hyun [Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Joellabuk-do 55324 (Korea, Republic of); Ryu, Sang-Wan; Lee, June Key [Optoelectronics Convergence Research Center, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186 (Korea, Republic of); Ha, Jun-Seok, E-mail: jsha@jnu.ac.kr [Optoelectronics Convergence Research Center, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186 (Korea, Republic of)

2017-04-15

Highlights: • The 1–5 period InGaN/GaN quantum well (QW) structures were grown on sapphire. • The photoelectrochemical properties of these structures were investigated. • The saturated photocurrent density increased with increasing number of QW pairs. • But, it was different in the stability of the photoanode. • We reported the reason for this difference. - Abstract: In this study, the effects of the number of quantum well (QW) pairs on the photoelectrochemical (PEC) properties of InGaN/GaN multi-QW structures (MQWs) were investigated. MQW samples were grown using metal-organic chemical vapor deposition, and their structural characteristics were confirmed by X-ray diffraction measurements. The photoluminescence measurements revealed that the optical properties of MQWs may be related to the PEC properties. The cyclic voltammetry data revealed that the saturated photocurrent density increased with increasing number of QW pairs; the photocurrent density of MQW5 was twice that of an nGaN reference. However, in the chronoamperometry measurement of the photoanode stability, MQWs with 3 QWs displayed the highest photocurrent stability, although the saturated photocurrent density was highest for MQW5. This was also confirmed by field-emission scanning electron microscopy of the surface morphology after PEC measurements. The stability and photocurrent density may be attributed to the quality of crystallinity of the MQWs.

Thermal stability of low dose Ga+ ion irradiated spin valves

International Nuclear Information System (INIS)

Qi Xianjin; Wang Yingang; Zhou Guanghong; Li Ziquan

2009-01-01

The thermal stability of low dose Ga + ion irradiated spin valves has been investigated and compared with that of the as-prepared ones. The dependences of exchange field, measured using vibrating sample magnetometer at room temperature, on magnetic field sweep rate and time spent at negative saturation of the pinned ferromagnetic layer, and training effect were explored. The training effect is observed on both the irradiated spin valves and the as-prepared ones. The magnetic field sweep rate dependence of the exchange bias field of the irradiated spin valves is nearly the same as that of the as-prepared ones. For the as-prepared structure thermal activation has been observed, which showed that holding the irradiated structure at negative saturation of the pinned ferromagnetic layer for up to 28 hours results in no change in the exchange field. The results indicate that the thermal stability of the ion irradiated spin valves is the same as or even better than the as-prepared ones.

Development of prototype induced-fission-based Pu accountancy instrument for safeguards applications.

Science.gov (United States)

Seo, Hee; Lee, Seung Kyu; An, Su Jung; Park, Se-Hwan; Ku, Jeong-Hoe; Menlove, Howard O; Rael, Carlos D; LaFleur, Adrienne M; Browne, Michael C

2016-09-01

Prototype safeguards instrument for nuclear material accountancy (NMA) of uranium/transuranic (U/TRU) products that could be produced in a future advanced PWR fuel processing facility has been developed and characterized. This is a new, hybrid neutron measurement system based on fast neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) methods. The FNEM method is sensitive to the induced fission rate by fast neutrons, while the PNAR method is sensitive to the induced fission rate by thermal neutrons in the sample to be measured. The induced fission rate is proportional to the total amount of fissile material, especially plutonium (Pu), in the U/TRU product; hence, the Pu amount can be calibrated as a function of the induced fission rate, which can be measured using either the FNEM or PNAR method. In the present study, the prototype system was built using six (3)He tubes, and its performance was evaluated for various detector parameters including high-voltage (HV) plateau, efficiency profiles, dead time, and stability. The system's capability to measure the difference in the average neutron energy for the FNEM signature also was evaluated, using AmLi, PuBe, (252)Cf, as well as four Pu-oxide sources each with a different impurity (Al, F, Mg, and B) and producing (α,n) neutrons with different average energies. Future work will measure the hybrid signature (i.e., FNEM×PNAR) for a Pu source with an external interrogating neutron source after enlarging the cavity size of the prototype system to accommodate a large-size Pu source (~600g Pu). Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved MOX fuel calculations using new Pu-239, Am-241 and Pu-240 evaluations

International Nuclear Information System (INIS)

Noguere, G.; Bouland, O.; Bernard, D.; Leconte, P.; Blaise, P.; Peneliau, Y.; Vidal, J.F.; Saint Jean, C. de; Leal, L.; Schilleebeeckx, P.; Kopecky, S.; Lampoudis, C.

2013-01-01

Several studies based on the JEFF-3.1.1 nuclear data library show a systematic over-estimation of the critical keff for core configurations of MOX fuel assemblies. The present work investigates possible improvements of the C/E results by using new evaluations for Am-241, Pu-239 and Pu-240. The work reported in this paper demonstrates the performances of the new Am-241 evaluation based on capture and transmission data measured at the IRMM. For Pu-239, the new evaluation, established in the frame of the WPEC/SG-34, is able to explain a systematic discrepancy observed between different EOLE experiments. The combination of the Am-241 and Pu-239 evaluations demonstrates the necessity to improve the radiation width of the first resonance of Pu-240

Determination of 240Pu/239Pu isotope ratios in Kara Sea and Novaya Zemlya sediments using accelerator mass spectrometry

International Nuclear Information System (INIS)

Oughton, D.H.; Skipperud, L.; Salbu, B.; Fifield, L.K.; Cresswell, R.C.; Day, J.P.

1999-01-01

Accelerator mass spectrometry (AMS) has been used to determine Pu activity concentrations and 240 Pu/ 239 Pu isotope ratios in sediments from the Kara Sea and radioactive waste dumping sites at Novaya Zemlya. Measured 239,240 Pu activities ranged from 0.06 - 9.8 Bq/kg dry weight, 240 Pu/ 239 Pu atom ratios ranged from 0.13 to 0.28, and 238 Pu/ 239,240 Pu activity ratios from 0.02 to 0.6. Perturbations from global fallout isotope ratios were evident at three sites: the Yenisey Estuary and Abrosimov Fjords where 240 Pu/ 239 Pu ratios were lower (0.13-0.14); and Stepovogo Fjord sediments where ratios were higher (up to 0.28) than fallout ratios. Based on procedural blanks, detection limits for AMS were below 1 fg Pu and the method showed good precision for isotope ratio measurements, minimal matrix, interference and memory effects. For high level samples, comparison between alpha spectrometry and AMS gave good agreement for measurement of 239,240 Pu activity concentrations. (author)

Natural Pu-traces within the continental crust

International Nuclear Information System (INIS)

Ganz, M.; Barth, H.; Fuest, M.; Molzahn, D.; Brandt, R.

1991-01-01

Pu-traces are observed in the environmental all over the world, 'man made'-Pu as well as 'natural' Pu ( 239 Pu). 239 Pu occurs within a range of about 10 -12 g Pu/g sample in pitchblende. In the FRG, the deep-drilling project 'KTB, Kontinentales Tiefbohrprogramm', was started with the aim to obtain a very deep hole (14 km). We wanted to establish upper concentration limits for plutonium in samples from KTB. For a first investigation, we obtained a 400 g sample of granite from a pre-drill of KTB. Its Pu-concentration was ≤ (4.5 ± 2.5)x10 -16 g 239 Pu/g sample. To compare this result to the Pu-content in geological brines, we obtained a sample from a borehole at the Salton Sea Geothermal field (Southeastern California). In this sample we found an upper concentration limit of (2.1 ± 1.0)x10 -16 g 239 Pu/g sample. (orig.)

Crystallography and magnetic properties of transuranium element oxygen compounds (Np, Pu and Am)

International Nuclear Information System (INIS)

Tabuteau, Alain.

1981-05-01

This paper includes: 1) The brief description of the experimental techniques used for analyzing very small quantities of solid radioactive compounds (differential thermal micro-analyses, diffraction of X rays, magnetic susceptibility and Moessbauer resonance). 2) The methods of synthesis of the ternary oxides of transuranic elements at oxidation degrees III (Pu 2 MoO 6 , Pu 2 WO 6 , Pu 2 (WO 4 ) 3 , Am 2 MoO 6 , Am 2 WO 6 , Am 2 (MoO 4 ) 3 and Am 2 (WO 4 ) 3 ) and at degree IV (Np(VO 3 ) 4 , Np(MoO 4 ) 2 , Np(WO 4 ) 2 and Pu(MoO 4 ) 2 ). The drawing up of liquid-solid balance diagrams enabled the field of stability of molybdate (or tungstate) systems of alkaline transuranic - mobybdates (or tungstates) to be clarified. 3) The study of the structural properties of the identified phases. These results taken as a whole made it possible to establish a ''comparative crystal - chemistry'' of the oxigenated phases of Np, Pu and Am with those of the thorium and uranium actinide elements and with the rare earths of adjacent ionic radius. 4) The Moessbauer resonance study of 237 Np in the solid solution Usub(1-x)Npsub(x)O 2 (0 [fr

Exploring the radiosynthesis and in vitro characteristics of [68 Ga]Ga-DOTA-Siglec-9.

Science.gov (United States)

Jensen, Svend B; Käkelä, Meeri; Jødal, Lars; Moisio, Olli; Alstrup, Aage K O; Jalkanen, Sirpa; Roivainen, Anne

2017-07-01

Vascular adhesion protein 1 is a leukocyte homing-associated glycoprotein, which upon inflammation rapidly translocates from intracellular sources to the endothelial cell surface. It has been discovered that the cyclic peptide residues 283-297 of sialic acid-binding IgG-like lectin 9 (Siglec-9) "CARLSLSWRGLTLCPSK" bind to vascular adhesion protein 1 and hence makes the radioactive analogues of this compound ([ 68 Ga]Ga-DOTA-Siglec-9) interesting as a noninvasive visualizing marker of inflammation. Three different approaches to the radiosynthesis of [ 68 Ga]Ga-DOTA-Siglec-9 are presented and compared with previously published methods. A simple, robust radiosynthesis of [ 68 Ga]Ga-DOTA-Siglec-9 with a yield of 62% (non decay-corrected) was identified, and it had a radiochemical purity >98% and a specific radioactivity of 35 MBq/nmol. Furthermore, the protein binding and stability of [ 68 Ga]Ga-DOTA-Siglec-9 were analyzed in vitro in mouse, rat, rabbit, pig, and human plasma and compared with in vivo pig results. The plasma in vitro protein binding of [ 68 Ga]Ga-DOTA-Siglec-9 was the lowest in the pig followed by rabbit, human, rat, and mouse. It was considerably higher in the in vivo pig experiments. The in vivo stability in pigs was lower than the in vitro stability. Despite considerable species differences, the observed characteristics of [ 68 Ga]Ga-DOTA-Siglec-9 are suitable as a positron emission tomography tracer. Copyright © 2017 John Wiley & Sons, Ltd.

Review of the thermodynamics of the U--C, Pu--C, and U--Pu--C systems

International Nuclear Information System (INIS)

Tetenbaum, M.; Sheth, A.; Olson, W.

1975-06-01

Thermodynamic properties such as enthalpy, heat capacity, entropy, heat and free energy of formation, and vaporization behavior are presented for the U--C, Pu--C, and U--Pu--C systems. These properties are of interest to scientists and engineers involved in the expanding field of advanced fuel LMFBR systems. The information on these systems has been derived largely from the discussions of the IAEA Panel on the assessment of thermodynamic properties of the U--C, Pu--C, and U--Pu--C systems. (U.S.)

Designing Pu600 for Authentication

International Nuclear Information System (INIS)

White, G.

2008-01-01

Many recent Non-proliferation and Arms Control software projects include an authentication component. Demonstrating assurance that software and hardware performs as expected without hidden 'back-doors' is crucial to a project's success. In this context, 'authentication' is defined as determining that the system performs only its intended purpose and performs that purpose correctly and reliably over many years. Pu600 is a mature software solution for determining the presence of Pu and the ratio of Pu240 to Pu239 by analyzing the gamma ray spectra in the 600 KeV region. The project's goals are to explore hardware and software technologies which can by applied to Pu600 which ease the authentication of a complete, end-to-end solution. We will discuss alternatives and give the current status of our work

Sintering Studies of Ga-Doped CeO2 (Ga-Doped PuO2 Surrogate) for Mixed Oxide Nuclear Fuel

International Nuclear Information System (INIS)

Haertling, C.; Huling, J.; Park, Y.S.

1999-01-01

Sintering studies of CeO 2 and CeO 2 + 2 wt. % Ga 2 O 3 were completed. Firing temperatures studied were 1250-1650 C with 2 to 4 hour firing soak times in air. Powders fabricated by three methods (as-received, attrition-mill and nitrite-derived) were studied. Attrition-milled CeO 2 improved densities as compared with as-received CeO 2 . Attrition-milled CeO 2 with 2 wt.% Ga 2 O 3 showed decreased densities with increasing temperatures. As-received CeO 2 with 2 wt.% Ga 2 O 3 showed a opposite trend, increasing in density with increased firing temperature. Two pellet preparation methods were studied, a one-step-press method and a two-step-press method. The two-step-press method showed greater densities at lower firing temperatures and times as compared with the one-step-press method, however for CeO 2 + 2 wt.% Ga 2 O 3 , the two methods gave equivalent results at 1650 C, 6 hr. firing conditions

High thermal stability of abrupt SiO2/GaN interface with low interface state density

Science.gov (United States)

Truyen, Nguyen Xuan; Taoka, Noriyuki; Ohta, Akio; Makihara, Katsunori; Yamada, Hisashi; Takahashi, Tokio; Ikeda, Mitsuhisa; Shimizu, Mitsuaki; Miyazaki, Seiichi

2018-04-01

The effects of postdeposition annealing (PDA) on the interface properties of a SiO2/GaN structure formed by remote oxygen plasma-enhanced chemical vapor deposition (RP-CVD) were systematically investigated. X-ray photoelectron spectroscopy clarified that PDA in the temperature range from 600 to 800 °C has almost no effects on the chemical bonding features at the SiO2/GaN interface, and that positive charges exist at the interface, the density of which can be reduced by PDA at 800 °C. The capacitance-voltage (C-V) and current density-SiO2 electric field characteristics of the GaN MOS capacitors also confirmed the reduction in interface state density (D it) and the improvement in the breakdown property of the SiO2 film after PDA at 800 °C. Consequently, a high thermal stability of the SiO2/GaN structure with a low fixed charge density and a low D it formed by RP-CVD was demonstrated. This is quite informative for realizing highly robust GaN power devices.

Evaluation of fission cross sections and covariances for 233U, 235U, 238U, 239Pu, 240Pu, and 241Pu

International Nuclear Information System (INIS)

Kawano, Toshihiko; Matsunobu, Hiroyuki; Murata, Toru

2000-02-01

A simultaneous evaluation code SOK (Simultaneous evaluation on KALMAN) has been developed, which is a least-squares fitting program to absolute and relative measurements. The SOK code was employed to evaluate the fission cross sections of 233 U, 235 U, 238 U, 239 Pu, 240 Pu, and 241 Pu for the evaluated nuclear data library JENDL-3.3. Procedures of the simultaneous evaluation and the experimental database of the fission cross sections are described. The fission cross sections obtained were compared with evaluated values given in JENDL-3.2 and ENDF/B-VI. (author)

Evaluation of nuclear data of {sup 244}Pu and {sup 237}Pu

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, Tsuneo; Konshin, V.A. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1995-10-01

The evaluation of nuclear data for {sup 244}Pu and {sup 237}Pu was made in the neutron energy region from 10{sup -5} eV to 20 MeV. For the both nuclides, the total, elastic and inelastic scattering, fission, capture, (n,2n) and (n,3n) reaction cross sections were evaluated on the basis of theoretical calculation. The resonance parameters were given for {sup 244}Pu. The angular and energy distributions of secondary neutrons were also estimated for the both nuclides. The results were compiled in the ENDF-5 format and will be adopted in JENDL Actinoid File. (author).

Studies of U-Pu-C-Ti compounds

International Nuclear Information System (INIS)

Milet, C.

1967-01-01

The U-Pu-C-Ti compounds (5 to 20 atoms per cent Ti) have been studied in order to improve some properties of U-Pu-C carbides and to extend the existence field of the (U, Pu) C phase. The Pu/(U+Pu) ratio has been fixed to 15 per cent. All the alloys were elaborated and cast in an arc furnace. A two-phases field (U, Pu) C + Ti C exists which permits to avoid di- and sesqui-carbides and the (U, Pu) phase. An eutectic between (U, Pu) C and Ti C was found around 15 atoms per cent Ti. Practically the whole of the titanium is in Ti C form, titanium solubility in (U, Pu) C being inferior to 1 atom per cent. The most promising alloy are those containing two phases: (U, Pu) C+ Ti C. In comparison with the (U, Pu) C phase, titanium addition does not change very much the thermal expansion coefficients nor the thermal cycling behaviour between 160 and 1000 Celsius degrees which is excellent. On the other hand atmospheric corrosion behaviour is improved; compatibility with stainless steel is better; thermal conductivity, calculated from electrical resistivity K is enhanced: for U(0.85)-Pu(0.15)-C alloy we have K 0.179 W/cm.C at 1000 C and K = 0.187 W/cm.C at 1500 C, for U-Pu-C-Ti (10 atoms % Ti) alloy we have K = 0.193 W/cm.C at 1000 C and K = 0.205 W/cm.C at 1500 C. (author) [fr

Preferential adsorption of gallium on GaAs(111)B surfaces during the initial growth of Au-assisted GaAs nanowires

International Nuclear Information System (INIS)

Shu Haibo; Chen Xiaoshuang; Ding Zongling; Dong Ruibin; Lu Wei

2010-01-01

The mechanism of the preferential adsorption of Ga on GaAs(111)B surfaces during the initial growth of Au-assisted GaAs nanowires is studied by using first-principles calculations within density functional theory. The calculated results show that Au preadsorption on GaAs(111)B surface significantly enhances the stability of the Ga adatom in comparison with the adsorption of Ga on clean GaAs(111)B surface. The stabilization of the Ga adatom is due to charge transfers from the Ga 4p and 4s states to the Au 6s and As 4p states. The number of Ga adatoms stabilized on GaAs(111)B surfaces depends on the size of surface Au cluster. The reason is that Au acted as an electron acceptor on GaAs(111)B surface assists the charge transfer of Ga adatoms for filling the partial unoccupied bands of GaAs(111)B surface. Our results are helpful to understand the growth of Au-assisted GaAs nanowires.

Local atomic structure of α-Pu

International Nuclear Information System (INIS)

Espinosa, F. J.; Villella, P.; Lashley, J. C.; Conradson, S. D.; Cox, L. E.; Martinez, R.; Martinez, B.; Morales, L.; Terry, J.; Pereyra, R. A.

2001-01-01

The local atomic structure of α-Pu was investigated using x-ray absorption fine structure (XAFS) spectroscopy. XAFS spectra were obtained for a zone-refined α-Pu and the results were compared to 32-year-old and Ce-doped (0.34 at.%) samples. X-ray diffraction (XRD) patterns were also measured for the zone-refined and 32-year-old materials. The extent of the Bragg peaks showed that amorphization of the 32-year-old sample had not occurred despite the prolonged exposure to self-radiation. Analogous to metastable δ-Pu alloys, the local atomic structure around Pu for the zone-refined material shows the possible presence of noncrystallographic Pu-Pu distances. Conversely, the Ce and the 32-year-old sample show no evidence for such noncrystallographic distances. Disorder in the Pu local environment was found to be impurity dependent. The Ce-doped sample presented a larger Pu-Pu nearest neighbor disorder than the aged sample, although the total amount of Am, U, and He impurities was actually higher in the aged sample. The local environment around U and Ce impurities is consistent with these elements being in substitutional lattice sites. In addition, U and Ce do not introduce significant lattice distortion to their nearest neighbors. This is consistent with disorder being more related to the perturbation of the coupling between the electronic and crystal structure, or the Peierls--Jahn-Teller distortion that generates the monoclinic α-Pu structure, and less to strain fields produced in the vicinity of the impurities

Designing Pu600 for Authentication

Energy Technology Data Exchange (ETDEWEB)

White, G

2008-07-10

Many recent Non-proliferation and Arms Control software projects include an authentication component. Demonstrating assurance that software and hardware performs as expected without hidden 'back-doors' is crucial to a project's success. In this context, 'authentication' is defined as determining that the system performs only its intended purpose and performs that purpose correctly and reliably over many years. Pu600 is a mature software solution for determining the presence of Pu and the ratio of Pu240 to Pu239 by analyzing the gamma ray spectra in the 600 KeV region. The project's goals are to explore hardware and software technologies which can by applied to Pu600 which ease the authentication of a complete, end-to-end solution. We will discuss alternatives and give the current status of our work.

Early retention of 237Pu + 239Pu in mature beagles

International Nuclear Information System (INIS)

Lloyd, R.D.; McFarland, S.S.; Atherton, D.R.; Bruenger, F.W.; Taylor, G.N.; Mays, C.W.

1978-01-01

Five mature beagles, ranging in age from 57 to 84 months, were injected intravenously with about 0.05-0.1 μCi/kg of 239 Pu(IV) citrate to which tracer amounts of the photon-emitter 237 Pu had been added. Plutonium retention in liver and in non-liver tissue (mainly skeleton) was measured periodically in the living dogs for nearly 4 months after injection by a combination of total-body and partial-body counting. All excreta were collected during the first 21 days and analysed for their Pu content. One dog was sacrificed at 14 days and another at 118 days for distribution studies. About 17% (14-20%) of the injected Pu was excreted in the urine and feces in the first 3 weeks, about the same as that excreted in a corresponding time by beagles injected as young adults (14%), but substantially more than beagles injected as juveniles (11%). In contrasts to juvenile beagles injected at 3 months of age, in which early retention was about 12% in liver and 68% in the skeleton, mature beagles retained about 30% in liver and 50% in the skeleton. Retention in young adult beagles injected at 17 months of age was similar to that of mature dogs. Relative distribution of skeletal plutonium among various bones was similar in the mature animals to that seen previously in young adults, but quite different from that of juveniles. A notable exception was the humerus for which there was no significant difference (P>0.2) in the % of retained skeletal Pu represented by the humerus among the juvenile, young adult and mature dogs. (author)

Metalorganic chemical vapor deposition growth of high-mobility AlGaN/AlN/GaN heterostructures on GaN templates and native GaN substrates

Energy Technology Data Exchange (ETDEWEB)

Chen, Jr-Tai, E-mail: jrche@ifm.liu.se; Hsu, Chih-Wei; Forsberg, Urban; Janzén, Erik [Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE 581 83 Linköping (Sweden)

2015-02-28

Severe surface decomposition of semi-insulating (SI) GaN templates occurred in high-temperature H{sub 2} atmosphere prior to epitaxial growth in a metalorganic chemical vapor deposition system. A two-step heating process with a surface stabilization technique was developed to preserve the GaN template surface. Utilizing the optimized heating process, a high two-dimensional electron gas mobility ∼2000 cm{sup 2}/V·s was obtained in a thin AlGaN/AlN/GaN heterostructure with an only 100-nm-thick GaN spacer layer homoepitaxially grown on the GaN template. This technique was also demonstrated viable for native GaN substrates to stabilize the surface facilitating two-dimensional growth of GaN layers. Very high residual silicon and oxygen concentrations were found up to ∼1 × 10{sup 20 }cm{sup −3} at the interface between the GaN epilayer and the native GaN substrate. Capacitance-voltage measurements confirmed that the residual carbon doping controlled by growth conditions of the GaN epilayer can be used to successfully compensate the donor-like impurities. State-of-the-art structural properties of a high-mobility AlGaN/AlN/GaN heterostructure was then realized on a 1 × 1 cm{sup 2} SI native GaN substrate; the full width at half maximum of the X-ray rocking curves of the GaN (002) and (102) peaks are only 21 and 14 arc sec, respectively. The surface morphology of the heterostructure shows uniform parallel bilayer steps, and no morphological defects were noticeable over the entire epi-wafer.

Two 238Pu inhalation incidents

International Nuclear Information System (INIS)

Fleming, R.R.; Hall, R.M.

1978-06-01

Two employees inhaled significant amounts of 238 Pu in separate unrelated contamination incidents in 1977. Both acute exposure incidents are described and the urine, feces, and in-vivo chest count data for each employee. Case B ( 238 PuNO 3 ) received 24 DTPA treatments beginning the day of the incident while, for medical reasons, Case A ( 238 PuO 2 ) received no therapy

Thermal stability and in situ SiN passivation of InAlN/GaN high electron mobility heterostructures

Energy Technology Data Exchange (ETDEWEB)

Lugani, L.; Carlin, J.-F.; Py, M. A.; Grandjean, N. [ICMP, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2014-09-15

We investigate the thermal stability of nearly lattice-matched InAlN layers under metal organic vapor phase epitaxy conditions for temperatures >800 °C and show that they are not fully stable. In particular, InAlN top layers undergo degradation during high temperature annealing due to a surface related process, which causes the loss of crystal quality. This strongly impacts the transport properties of InAlN/GaN HEMT heterostructures; in particular, the mobility is significantly reduced. However, we demonstrate that high thermal stability can be achieved by capping with a GaN layer as thin as 0.5 nm. Those findings enabled us to realize in situ passivated HEMT heterostructures with state of the art transport properties.

239Pu(n, 2n) and 241Pu(n, 2n) surrogate cross section measurements using NeutronSTARS

Energy Technology Data Exchange (ETDEWEB)

Burke, J. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alan, B. S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Akindele, O. A. [Univ. of California, Berkeley, CA (United States); Casperson, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hughes, R. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Koglin, J. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tamashiro, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oregon State Univ., Corvallis, OR (United States); Kolos, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Norman, E. B. [Univ. of California, Berkeley, CA (United States); Saastamoinen, A. [Univ. of California, Los Angeles, CA (United States); Padilla, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Los Angeles, CA (United States); Fisher, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-12-08

The goal of this project was to develop a new approach to measuring (n,2n) reactions for isotopes of interest. We set out to measure the ²³⁹Pu(n,2n) and ²⁴¹Pu(n,2n) cross sections by directly detecting the 2n neutrons that are emitted. With the goal of improving the ²³⁹Pu(n,2n) cross section and to measure the ²⁴¹Pu(n,2n) cross section for the first time. To that end, we have constructed a new neutron-charged-particle detector array called NeutronSTARS. It has been described extensively in Casperson et al. [1] and in Akindele et al. [2]. We have used this new neutron-charged-particle array to measure the ²⁴¹Pu and ²³⁹Pu fission neutron multiplicity as a function of equivalent incident-neutron energy from 100 keV to 20 MeV. We have made a preliminary determination of the ²³⁹Pu(n,2n) and ²⁴¹Pu(n,2n) cross sections from the surrogate ²⁴⁰Pu(α,α’2n) and ²⁴²Pu(α,α’2n) reactions respectively. The experimental approach, detector array, data analysis, and results to date are summarized in the following sections.

Presence of plutonium isotopes, {sup 239}Pu and {sup 240}Pu, in soils from Chile

Energy Technology Data Exchange (ETDEWEB)

Chamizo, E., E-mail: echamizo@us.es [Centro Nacional de Aceleradores, Avda. Thomas Alba Edison, 7, 41092 Sevilla (Spain); Garcia-Leon, M., E-mail: manugar@us.es [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Avda. Reina Mercedes sn, 41012 Seville (Spain); Peruchena, J.I., E-mail: jiperuchena@gmail.com [Centro Nacional de Aceleradores, Avda. Thomas Alba Edison, 7, 41092 Sevilla (Spain); Cereceda, F., E-mail: francisco.cereceda@usm.cl [Laboratorio de Quimica Ambiental, Centro de Tecnologias Ambientales (CETAM), Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Vidal, V., E-mail: victor.vidal@usm.cl [Laboratorio de Quimica Ambiental, Centro de Tecnologias Ambientales (CETAM), Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Pinilla, E., E-mail: epinilla@unex.es [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas sn, 06071 Badajoz (Spain); Miro, C., E-mail: cmiro@unex.es [Departamento de Fisica Aplicada, Universidad de Extremadura, Avda. de la Universidad sn, 10071 Caceres (Spain)

2011-12-15

Plutonium is present in every environmental compartment, due to a variety of nuclear activities. The Southern Hemisphere has received about 20% of the global {sup 239}Pu and {sup 240}Pu environmental inventory, with an important contribution of the so-called tropospheric fallout from both the atmospheric nuclear tests performed in the French Polynesia and in Australia by France and United Kingdom, respectively. In this work we provide new data on the impact of these tests to South America through the study of {sup 239}Pu and {sup 240}Pu in soils from different areas of Northern, Central and Southern Chile. The obtained results point out to the presence of debris from the French tests in the 20-40 Degree-Sign Southern latitude range, with {sup 240}Pu/{sup 239}Pu atomic ratios quite heterogeneous and ranging from 0.02 to 0.23. They are significantly different from the expected one for the global fallout in the Southern Hemisphere for the 30-53 Degree-Sign S latitude range (0.185 {+-} 0.047), but they follow the same trend as the reported values by the Department of Energy of United States for other points with similar latitudes. The {sup 239+240}Pu activity inventories show as well a wider variability range in that latitude range, in agreement with the expected heterogeneity of the contamination.

Towards a spectroscopic standard database for Pu in repository environments

International Nuclear Information System (INIS)

Amme, M.

2005-01-01

Full text of publication follows: The alteration behaviour of Pu in geological and technical environments is, although of crucial importance for example in final repository assessment procedures for high-level nuclear waste, not sufficiently investigated. Since Pu chemistry differs significantly from U behaviour (mostly due to the different stabilities of the +IV oxidation states of both elements), conclusions based on the uranium analogy cannot be extended to Pu chemistry in many cases. In order to examine precisely the alteration behaviour of Pu under repository storage conditions, customized tools for the spectroscopic identification of the element need to be developed. We are currently constructing systematically a database of Pu compounds and collect their spectra for this purpose. Pu compounds (with the element in the oxidation states +III, +IV, +V, and +VI) are synthesised, mostly by using hydrothermal synthesis techniques [1]. Compounds of high importance for repository studies are: Carbonates, (oxy)hydroxides, silicates, peroxides, and phosphates. The products are characterised by Scanning Electron Microscopy (SEM), X-Ray Photoelectron spectroscopy (XPS), and X-Ray diffraction (XRD). Furthermore, vibrational spectra (Raman and IR) of the substances will be recorded. These will allow the unambiguous identification of chemically similar compounds, once the database is compiled: Although reported for a few cases with nuclear material only, the combined investigation of solids with Raman [2,3] and SEM-EDX [3] in a combined mode, especially when spatially resolving, holds great potential An investigation with accelerator-based XAS techniques is planned within the framework of the Excellence network Actinet 6. [1] Grigorev, M., Bessonov, A., Makarenkov, V., Fedoseev, A., Model of the (PuO 2 ) 2 SiO 4 * 2H 2 O crystal structure, based on powder X-ray diffraction data, Radiochemistry, Vol. 45, No 3 (2003) 257-260. [2] M. Amme, B. Renker, B. Schmid, M. Feth, H

Anthropogenic Pu distribution in Tropical East Pacific

International Nuclear Information System (INIS)

Kinoshita, Norikazu; Sumi, Takahiro; Takimoto, Kiyotaka; Nagaoka, Mika; Yokoyama, Akihiko; Nakanishi, Takashi

2011-01-01

The geographical distribution of the anthropogenic radionuclides 238 Pu and 239+240 Pu in the Tropical East Pacific in 2003 was studied from the viewpoint of material migration. We measured the contents of Pu isotopes in seawater and in sediment from the sea bottom. The distributions of Pu isotopes, together with those of coexisting nitrate and phosphate species and dissolved oxygen, are discussed in relation to the potential temperature and potential density (sigma-θ). The Pu contents in sediment samples were compared with those in the seawater. Horizontal migration across the Equator from north to south was investigated at depths down to ∼ 800 m in the eastern Pacific. The Pu distribution at 0-400 m correlated well with the distribution of potential temperature. Maximum Pu levels were observed in the subsurface layer at 600-800 m, corresponding to the depth where sigma-θ ∼ 27.0. It is suggested that the Pu distribution depends on the structure of the water mass and the particular temperature and salinity. The water column/sediment column inventory ratio and the vertical distribution of Pu may reflect the efficiency of scavenging in the relevant water areas. Research Highlights: → Geographical distributions of Pu isotopes were investigated from viewpoint of material migration. → Horizontal migration from north to south was found at depths down to ∼800 m in the eastern Pacific. → Pu distribution at 0-400 m was correlated with water temperature. → The distribution at 600-800 m correlated with water mass structure. → Pu in seawater and sediment gave information about efficiency of scavenging.

Impact of an extruded nucleotide on cleavage activity and dynamic catalytic core conformation of the hepatitis delta virus ribozyme

Czech Academy of Sciences Publication Activity Database

Šefčíková, J.; Krasovská, Maryna V.; Špačková, Naďa; Šponer, Jiří; Walter, N.G.

2007-01-01

Roč. 85, 5-6 (2007), s. 392-406 ISSN 0006-3525 R&D Projects: GA ČR(CZ) GA203/05/0388; GA ČR(CZ) GA203/05/0009; GA AV ČR(CZ) 1QS500040581; GA MŠk(CZ) LC512 Institutional research plan: CEZ:AV0Z50040702 Keywords : conformational dynamics * hepatitis delta virus * molecular dynamics Subject RIV: BO - Biophysics Impact factor: 2.389, year: 2007

Pu abundances, concentrations, and isotopics by x- and gamma-ray spectrometry assay techniques

International Nuclear Information System (INIS)

Camp, D.C.; Gunnink, R.; Ruhter, W.D.; Prindle, A.L.; Gomes, R.J.

1986-01-01

Two x- and gamma-ray systems were recently installed at-line in gloveboxes and will measure Pu solution concentrations from 5 to 105 g/L. These NDA technique, developed and refined over the past decade, are now used domestically and internationally for nuclear material process monitoring and accountability needs. In off- and at-line installations, they can measure solution concentrations to 0.2%. The K-XRFA systems use a transmission source to correct for solution density. The gamma-ray systems use peaks from 59- to 208-keV to determine solution concentrations and relative isotopics. A Pu check source monitors system stability. These two NDA techniques can be combined to form a new, NDA measurement methodology. With the instrument located outside of a glovebox, both relative Pu isotopics and absolute Pu abundances of a sample located inside a glovebox can be measured. The new technique works with either single or dual source excitation; the former for a detector 6 to 20 cm away with no geometric corrections needed; the latter requires geometric corrections or source movement if the sample cannot be measured at the calibration distance. 4 refs., 7 figs., 2 tabs

Decay Lengths for Diffusive Transport Activated by Andreev Reflections in Al/n-GaAs/Al Superconductor-Semiconductor-Superconductor Junctions

DEFF Research Database (Denmark)

Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Clausen, Thomas

1997-01-01

In a highly doped GaAs semiconductor with superconducting contacts of Al, clear conductance peaks are observed at zero voltage bias and at V = +/-2 Delta/e, +/-Delta/e. The subharmonic energy gap structure originates from Andreev scattering with diffusive, but energy conserving, transport in the ...

Comparison of the ENDF/B-V and SOKRATOR evaluations of 235U, 239Pu, 240Pu and 241Pu at low neutron energies

International Nuclear Information System (INIS)

de Saussure, G.; Wright, R.Q.

1981-01-01

The US and USSR's most recent evaluationsof 235 U, 239 Pu, 240 Pu and 241 Pu are compared over the thermal region and over the first few resonances. The two evaluations rest on essentially the same experimental data base and the differences reflect different approaches to the representation of the cross sections or different weightings of the experimental results. It is found that over the thermal and resolved ranges the two evaluations are very similar. Some differences in approaches are briefly discussed

Glycosylation of alpha(2)delta(1) subunit: a sweet talk with Ca(v)1.2 channels

Czech Academy of Sciences Publication Activity Database

Lazniewska, Joanna; Weiss, Norbert

2016-01-01

Roč. 35, č. 3 (2016), s. 239-242 ISSN 0231-5882 R&D Projects: GA ČR GA15-13556S; GA MŠk 7AMB15FR015 Institutional support: RVO:61388963 Keywords : calcium channel * Ca(v)1.2 channel * ancillary subunit * alpha(2)delta(1) subunit * glycosylation * trafficking Subject RIV: CE - Biochemistry Impact factor: 1.170, year: 2016

An ab initio study of plutonium oxides surfaces; Etude ab initio des surfaces d'oxydes de Pu

Energy Technology Data Exchange (ETDEWEB)

Jomard, G.; Bottin, F.; Amadon, B

2007-07-01

By means of first-principles calculations, we have studied the atomic structure as well as the thermodynamic stability of various plutonium dioxide surfaces in function of their environment (in terms of oxygen partial pressure and temperature). All these simulations have been performed with the ABINIT code. It is well known that DFT fails to describe correctly plutonium-based materials since 5f electrons in such systems are strongly correlated. In order to go beyond DFT, we have treated PuO{sub 2} and {beta}-Pu{sub 2}O{sub 3} in a DFT+U framework. We show that the couple of parameters (U,J) that works well for pure Pu is also well designed for describing ground state (GS) properties of these two oxides. The major improvement with respect with DFT is that we are able to predict an insulating GS in agreement with experiments. The presence of a gap in the DOS (Density of States) of plutonium oxides should play a significant role in the predicted surface reactivity. However, performing DFT+U calculations on surfaces of plutonium oxide from scratch was too ambitious. That is why we decided, as a first step, to study the stability of the (100), (110) and (111) surfaces of PuO{sub 2} in a DFT-GGA framework. For each of these orientations, we considered various terminations. These ab initio results have been introduced in a thermodynamic model which allows us to predict the relative stability of the different terminations as a function of temperature and oxygen partial pressure (p{sub O{sub 2}}). We conclude that at room temperature and for p{sub O{sub 2}}{approx}10 atm., the polar O{sub 2}-(100) termination is favoured. The stabilization of such a polar stoichiometric surface is surprising and should be confirmed by DFT+U calculations before any final conclusion. (authors)

Organic matter composition and stabilization in a polygonal tundra soil of the Lena Delta

Directory of Open Access Journals (Sweden)

S. Höfle

2013-05-01

Full Text Available This study investigated soil organic matter (OM composition of differently stabilized soil OM fractions in the active layer of a polygonal tundra soil in the Lena Delta, Russia, by applying density and particle size fractionation combined with qualitative OM analysis using solid state 13C nuclear magnetic resonance spectroscopy, and lipid analysis combined with 14C analysis. Bulk soil OM was mainly composed of plant-derived, little-decomposed material with surprisingly high and strongly increasing apparent 14C ages with active layer depth suggesting slow microbial OM transformation in cold climate. Most soil organic carbon was stored in clay and fine-silt fractions (n-alkane and n-fatty acid compounds and low alkyl/O-alkyl C ratios. Organo-mineral associations, which are suggested to be a key mechanism of OM stabilization in temperate soils, seem to be less important in the active layer as the mainly plant-derived clay- and fine-silt-sized OM was surprisingly "young", with 14C contents similar to the bulk soil values. Furthermore, these fractions contained less organic carbon compared to density fractionated OM occluded in soil aggregates – a further important OM stabilization mechanism in temperate soils restricting accessibility of microorganisms. This process seems to be important at greater active layer depth where particulate OM, occluded in soil aggregates, was "older" than free particulate OM.

A 500-600 MHz GaN power amplifier with RC-LC stability network

Science.gov (United States)

Ma, Xinyu; Duan, Baoxing; Yang, Yintang

2017-08-01

A 500-600 MHz high-efficiency, high-power GaN power amplifier is designed and realized on the basis of the push-pull structure. The RC-LC stability network is proposed and applied to the power amplifier circuit for the first time. The RC-LC stability network can significantly reduce the high gain out the band, which eliminates the instability of the power amplifier circuit. The developed power amplifier exhibits 58.5 dBm (700 W) output power with a 17 dB gain and 85% PAE at 500-600 MHz, 300 μs, 20% duty cycle. It has the highest PAE in P-band among the products at home and abroad. Project supported by the National Key Basic Research Program of China (No. 2014CB339901).

Modulation-doped β-(Al0.2Ga0.8)2O3/Ga2O3 field-effect transistor

Science.gov (United States)

Krishnamoorthy, Sriram; Xia, Zhanbo; Joishi, Chandan; Zhang, Yuewei; McGlone, Joe; Johnson, Jared; Brenner, Mark; Arehart, Aaron R.; Hwang, Jinwoo; Lodha, Saurabh; Rajan, Siddharth

2017-07-01

Modulation-doped heterostructures are a key enabler for realizing high mobility and better scaling properties for high performance transistors. We report the realization of a modulation-doped two-dimensional electron gas (2DEG) at the β-(Al0.2Ga0.8)2O3/Ga2O3 heterojunction by silicon delta doping. The formation of a 2DEG was confirmed using capacitance voltage measurements. A modulation-doped 2DEG channel was used to realize a modulation-doped field-effect transistor. The demonstration of modulation doping in the β-(Al0.2Ga0.8)2O3/Ga2O3 material system could enable heterojunction devices for high performance electronics.

The radiolysis of solutions containing Pu(6)

International Nuclear Information System (INIS)

Rance, P.J.W.; Zilberman, B.Y.

2000-01-01

The reduction of Pu(VI) in nitric acid solutions containing uranium and various fission product elements as a result of both its inherent alpha radiation and also external gamma irradiation at dose rates similar to those experienced by dissolved fuel solutions has been investigated. The presence of the additional metals has been shown to eliminate the induction periods required prior to the reduction of Pu(VI) in nitric acid. G values for the auto-radiolytic reduction of Pu(VI) have been found to be between 0.6 and 1.1 for 3 g/1 Pu solutions containing between 0.12 and 9.2 % 238 Pu (balance 239 Pu). Uranium and palladium have been found to accelerate the reduction of Pu(VI) during gamma irradiation at dose rates of between 0.41 and 1.64 kGy/hour. (authors)

The radiolysis of solutions containing Pu(6)

Energy Technology Data Exchange (ETDEWEB)

Rance, P.J.W. [BNFL British Nuclear Fuels, Sellafield, Seascale, Cumbria, Research and Technology (United Kingdom); Zilberman, B.Y. [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation)

2000-07-01

The reduction of Pu(VI) in nitric acid solutions containing uranium and various fission product elements as a result of both its inherent alpha radiation and also external gamma irradiation at dose rates similar to those experienced by dissolved fuel solutions has been investigated. The presence of the additional metals has been shown to eliminate the induction periods required prior to the reduction of Pu(VI) in nitric acid. G values for the auto-radiolytic reduction of Pu(VI) have been found to be between 0.6 and 1.1 for 3 g/1 Pu solutions containing between 0.12 and 9.2 % {sup 238}Pu (balance {sup 239}Pu). Uranium and palladium have been found to accelerate the reduction of Pu(VI) during gamma irradiation at dose rates of between 0.41 and 1.64 kGy/hour. (authors)

Tidal controls on river delta morphology

Science.gov (United States)

Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

2017-09-01

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.

Computing and physical methods to calculate Pu

International Nuclear Information System (INIS)

Mohamed, Ashraf Elsayed Mohamed

2013-01-01

Main limitations due to the enhancement of the plutonium content are related to the coolant void effect as the spectrum becomes faster, the neutron flux in the thermal region tends towards zero and is concentrated in the region from 10 Ke to 1 MeV. Thus, all captures by 240 Pu and 242 Pu in the thermal and epithermal resonance disappear and the 240 Pu and 242 Pu contributions to the void effect became positive. The higher the Pu content and the poorer the Pu quality, the larger the void effect. The core control in nominal or transient conditions Pu enrichment leads to a decrease in (B eff.), the efficiency of soluble boron and control rods. Also, the Doppler effect tends to decrease when Pu replaces U, so, that in case of transients the core could diverge again if the control is not effective enough. As for the voiding effect, the plutonium degradation and the 240 Pu and 242 Pu accumulation after multiple recycling lead to spectrum hardening and to a decrease in control. One solution would be to use enriched boron in soluble boron and shutdown rods. In this paper, I discuss and show the advanced computing and physical methods to calculate Pu inside the nuclear reactors and glovebox and the different solutions to be used to overcome the difficulties that effect, on safety parameters and on reactor performance, and analysis the consequences of plutonium management on the whole fuel cycle like Raw materials savings, fraction of nuclear electric power involved in the Pu management. All through two types of scenario, one involving a low fraction of the nuclear park dedicated to plutonium management, the other involving a dilution of the plutonium in all the nuclear park. (author)

Metal-carbide multilayers for molten Pu containment

International Nuclear Information System (INIS)

Summers, T.S.E.; Curtis, P.G.; Juntz, R.S.; Krueger, R.L.

1991-12-01

Multilayers composed of nine or ten alternating layers of Ta or W and TaC were studied for the feasibility of their use in containing molten plutonium (Pu) at 1200 degrees C. Single layers of W and TaC were also investigated. A two-source electron beam evaporation process was developed to deposit these coatings onto the inside surface of hemispherical Ta cups about 38 mm in diameter. Pu testing was done by melting Pu in the coated hemispherical cups and holding them under vacuum at 1200 degrees C for two hours. Metallographic examination and microprobe analysis of cross sections showed that Pu had penetrated to the Ta substrate in all cases to some extent. Full penetration to the outer surface of the Ta substrate, however, occurred in only a few of the samples. The fact that full penetration occurred in any of the samples suggests that it would have occurred in uncoated Ta under these testing conditions which in turn suggests that the multilayer coatings do afford some protection against Pu attack. The TaC used for these specimens was wet by Pu under these testing conditions, and following testing, Pu was found uniformly distributed throughout the carbide layers which appeared to be rather porous. Pu was seen in the W and Ta layers only when exposed directly to molten Pu during testing or near defects suggesting that Pu penetrated the multilayers at defects in the coating and traveled parallel to the layers along the carbide layers. These results indicate that the use of alternating metal and ceramic layers for Pu containment should be possible through the use of nonporous ceramic that is not wet by molten Pu and defect-free films

Modification of analytical method for measurement of 239Pu, 240Pu and 241Am in sediment and sea water

International Nuclear Information System (INIS)

Syarbaini; Tarigan, C.; Rustam, M.F.

1997-01-01

Modification of analytical method for measurement of 239 Pu, 240 Pu and 241 Am in sediment and sea water have been conducted. This study is to develop a method for separation of 239 Pu, 240 Pu and 241 Am from 100-300 g of sediment and 100-200 l of sea water samples. Most of the methods described in the literature are to separation of '2 39 Pu, '2 40 Pu and 241 Am from 20-50 g of sediment and 30-100 l of sea water samples. By this method, 239,240 Pu and 241 Am were concentrated using the coprecipitation of CaC 2 O 4 and Fe (OH) 3 . Plutonium-242 and Curium-244 were used as tracer to determine chemical recovery. The result of analysis of some sediment samples showed that the chemical recoveries were respectively obtained in the range of 59.7 to 72.6% with average of 66.2 % for 242 Pu and 72.0 % to 85.5 % with average 78.8 % for 244 Cm. Analysis of some sea water samples were obtained in the range of 67 % to 78 % with average 73.9 % for 242 Pu and 74.0 % to 90.0 % with average 84.2 % for '2 42 Cm. This method was tested by the IAEA marine sediment, the result was excellent agreement with the IAEA certified sediment. It could be suggested that the developed analytical method is suitable to analyze the low level 239 Pu, 240 Pu and 241 Am in sediment and sea water samples (author)

Plutonium diffusion in advanced fuels (U,Pu)(C,O) and (U,Pu)(C,N)

International Nuclear Information System (INIS)

Bradbury, M.H.; Matzke, H.

1983-01-01

The self-diffusion of 238 Pu was measured in an oxicarbide (U,Pu)(C,O) and a carbonitride (U,Pu) (C,N). The activation enthalpies were 447 and 347 kJ mol -1 , respectively. The carbonitrides were confirmed to fall into three classes: carbide-like compositions with less than 30% nitrogen in the metalloid lattice, nitride-like composition with more than 70% nitrogen and with reduced atomic mobilities, and carbonitrides with about 50% nitrogen showing an intermediate behavior. The oxicarbide showed diffusion coefficients slightly larger than those of pure carbides

Use of combined alpha-spectrometry and fission track analysis for the determination of 240Pu/239Pu ratios in human tissue

International Nuclear Information System (INIS)

Love, S.F.; Filby, R.H.; Glover, S.E.; Stuit, D.B.; Kathren, R.L.

1998-01-01

Plutonium and other actinides were determined in human autopsy tissues of occupationally exposed workers who were registrants of the United States Transuranium and Uranium Registries (USTUR). In this study, Pu was purified and isolated from Am, U and Th, after drying and wet-ashing of the tissues, and the addition of 238 Pu as a radiotracer. After electrodeposition onto vanadium planchets, the 239+240 Pu activity was determined by alpha-spectrometry. A fission track method was developed to determine 239 Pu in the presence of 238 Pu and 240 Pu, using Lexan TM polycarbonate detectors. Combining the two techniques allowed the determination of the 240 Pu/ 239 Pu activity and atom ratios. Data from selected USTUR cases are presented. (author)

Semi-insulating GaAs detectors of fast neutrons

International Nuclear Information System (INIS)

Sagatova, A.; Sedlackova, K.; Necas, V.; Zatko, B.; Dubecky, F.; Bohacek, P.

2012-01-01

The present work deals with the technology of HDPE neutron conversion layer application on the surface of semi-insulating (SI) GaAs detectors via developed polypropylene (PP) based glue. The influence of glue deposition on the electric properties of the detectors was studied as well as the ability of the detectors to register the fast neutrons from "2"3"9Pu-Be neutron source. (authors)

Vertical profiles of 239(240)Pu, 238Pu and 241Am in some peculiar Italian mosses

International Nuclear Information System (INIS)

Testa, C.; Desideri, D.; Guerra, F.; Meli, M.A.; Roselli, C.; Jia, G.; Degetto, S.

2000-01-01

During the last two years the Urbino University and the Padua ICTIMA CNR were working on a special radioecological program having the aim to study the Pu and Am retention behaviour in different species of mosses growing in two Italian regions (Urbino, Central Italy, 450 m a.s.l. and Alps region, Northern Italy, 1500 m a.s.l.). 239,240 Pu, 238 Pu and 241 Am were separated and determined by extraction chromatography, electroplating and alpha spectrometry; 242 Pu and 243 Am were used as the yield tracers. The paper summarizes the results dealing with the vertical profiles of the radionuclides in three different species of mosses. Several 1-2 cm high sections were obtained and dated by 210 Pb determination. Typical concentration peaks for Pu and Am were found for very old moss species ('Sphagnum Compactum' and 'Sphagnum Nemoreum') at a depth corresponding to the early 1960's which is the period characterized by the maximum nuclear weapon tests. In more recent moss species ('Neckeria Crispa') no peak was observed and the regression curves showed that Am is more mobile than Pu. (author)

Risk estimates for lung tumours from inhaled 239PuO2, 238PuO2, and 239Pu(NO3)4 in beagle dogs

International Nuclear Information System (INIS)

Dagle, G.E.; Park, J.F.; Gilbert, E.S.; Weller, R.E.

1989-01-01

Lung cancer risks are being studied in beagle dogs given single exposures to aerosols of 239 PuO 2 , 238 PuO 2 , or 239 Pu(NO 3 ) 4 . A major objective of these studies is to examine the risk of lung cancer relative to the specific activity of the radionuclide, rate of dose accumulation due to differences in solubilities of the radionuclides, and the presence of competing risk from extrapulmonary lesions. Dose-response relationships were studied for the three groups of dogs, with analyses specifically designed to evaluate differences in response. Based on estimated cumulative dose to the lung, risks were found to differ significantly among the radionuclides; they were highest for 239 Pu(NO 3 ) 4 and lowest for 238 PuO 2 . A model in which the risk was assumed to be a pure quadratic function of dose fitted the data much better than a pure linear model. Currently, all three groups of dogs can be compared only to 10 years after exposure. However, it is apparent that the average cumulative dose to the lung may not be an adequate predictor of lung cancer risk for different isotopic and physicochemical forms of plutonium. (author)

HPLC method for determination of Th, U and Pu in irradiated (Th,Pu)O{sub 2} using mandelic acid as an eluent

Energy Technology Data Exchange (ETDEWEB)

Kumar, Pranaw; Paul, Sumana; Jaison, Perumpillil George; Telmore, Vijay Madhukar; Alamelu, Devanathan; Aggarwal, Suresh Kumar [Bhabha Atomic Research Centre, Mumbai (India). Fuel Chemistry Div.

2014-07-01

Studies for chromatographic separation of Th, U(VI) and Pu(IV) were carried out using mandelic acid as an eluent. The different chromatographic conditions like concentration of mandelic acid, pH of the mobile phase, presence of MeOH and effect of ion interaction reagent (IIR) were studied. The method was optimized for the separation of Th, U(VI) and Pu(IV). At pH<3.5 of mobile phase, Pu(IV) was more retained compared to U(VI) whereas at pH>3.5, reverse trend was observed. The optimized parameters were employed for the separation and determination of Th, U(VI) and Pu(IV) in a dissolved solution of irradiated (Th,Pu)O{sub 2}. Sample treatment was optimized to minimize loss of Pu and Th during chromatographic determination. Studies were carried out using two IIRs to understand the anomalous chromatographic behavior of Pu(IV). Retention behavior of different oxidation states of Pu viz. Pu(III), Pu(IV) and Pu(VI) was also studied in mandelic acid.

Unsafe Coulomb excitation of $^{240-244}Pu$

CERN Document Server

Wiedenhöver, I; Hackman, L; Ahmad, I; Greene, J P; Amro, H; Carpenter, M P; Nisius, D T; Reiter, P; Lauritsen, T; Lister, C J; Khoo, T L; Siem, S; Cizewski, J A; Seweryniak, D; Uusitalo, J; Macchiavelli, A O; Chowdhury, P; Seabury, E H; Cline, D; Wu, C Y

1999-01-01

The high spin states of /sup 240/Pu and /sup 244/Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a /sup 208/Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to /sup 242/Pu were obtained as well. In the case of /sup 244/Pu, the yrast band was extended to 34h(cross), revealing the completed pi i/sub 13/2/ alignment, a "first" for actinide nuclei. The yrast sequence of /sup 242/Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of /sup 240/Pu was measured up to the highest rotational frequencies ever reported in the actinide region (~300 keV), no sign of particle alignment was observed. (11 refs).

Structural, magnetic, electronic and optical properties of PuC and PuC{sub 0.75}: A hybrid density functional study

Energy Technology Data Exchange (ETDEWEB)

Yang, Rong [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); College of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Tang, Bin [School of Business Administration, Chongqing City Management College, Chongqing 401331 (China); Gao, Tao, E-mail: gaotao@scu.edu.cn [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Ao, BingYun, E-mail: aobingyun@caep.cn [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China)

2016-05-15

We perform first principles calculations to investigate the structural, magnetic, electronic and optical properties of PuC and PuC{sub 0.75}. Furthermore, we examine the influence of carbon non-stoichiometry on plutonium monocarbide. For the treatment of strongly correlated electrons, the hybrid density functionals like PBE0, Fock-0.25 are used and we compare the results with the generalized gradient approximation (GGA), local density approximation (LDA), LDA + U and experimental ones. The optimized lattice constant a{sub 0} = 4.961 Å for PuC in the Fock-0.25 scheme is the most close to the experimental data. The ground states of PuC and PuC{sub 0.75} are found to be anti-ferromagnetic. Our results indicate that additional removal of a C atom make lattice contract and new DOS peak appear in the near-Fermi region. We also compute and compare the optical properties of PuC and PuC{sub 0.75}. The difference in optical properties between PuC and PuC{sub 0.75} should also be the influence of carbon vacancies.

Direct identification of interstitial Mn in heavily p-type doped GaAs and evidence of its high thermal stability

CERN Document Server

Pereira, LMC; Correia, JG; Decoster, S; da Silva, MR; Araújo, JP; Vantomme, A

2011-01-01

We report on the lattice location of Mn in heavily p-type doped GaAs by means of $\\beta^{-}$-emission channeling from the decay of $^{56}$Mn. The majority of the Mn atoms substitute for Ga and up to 31% occupy the tetrahedral interstitial site with As nearest neighbors. Contrary to the general belief, we find that interstitial Mn is immobile up to 400$^{\\circ}$C, with an activation energy for diffusion of 1.7–2.3 eV. Such high thermal stability of interstitial Mn has significant implications on the strategies and prospects for achieving room temperature ferromagnetism in Ga$_{1−x}$Mn$_{x}$As.

Cation interdiffusion in the UO2 - (U, Pu)O2 and UO2 - PuO2 systems

International Nuclear Information System (INIS)

Leme, D.G.

1985-01-01

The interdiffusion of U and Pu ions in UO sub(2 +- x) - (U sub(0,83) Pu sub(0,17))O sub(2 + - x) and UO sub(2 + - x) -PuO sub(2 - x) sintered pellets and UO sub(2 +- x) -(U sub(0,82) Pu sub(0,18))O sub(2 + - x) single crystals has been studied as a function of the oxygen potential ΔG sup(-) (O 2 ) or the stoichiometric ratio O/M. The diffusion profiles of UO 2 /(U,Pu)O 2 and UO 2 /PuO 2 couples of different O/M ratios have been measured using high resolution α-spectrometer and microprobe. Thermal annealing of the specimens was performed in controlled atmospheres using either CO-CO 2 gas mixtures for constant O/M ratios or purified argon. The interdiffusion profiles have been analysed by means of the Boltzmann-Matano and Hall methods. The interdiffusion coefficient D sus(approx.) increases with increasing Pu content in sintered pellets (up to 17 wt. %PuO 2 ) showing a strong dependence of D sup(approx.) on the O/M ratio. The micropobe results show that the interdiffusion along grain boundaries is the main diffusion mechanism in the pellets. Experiments have also been carried out in single cristals to measure just the bulk-interdiffusion and avoiding effects due to grain boundaries. A marked dependence of D sup(approx.) on O/M ratio or on oxygen potential ΔG sup(-) (O 2 ), similar to the dependence already reported for self diffusion by means of radioactive tracers, has also been observed. (Author) [pt

Metalorganic chemical vapor deposition growth and thermal stability of the AlInN/GaN high electron mobility transistor structure

International Nuclear Information System (INIS)

Yu, Hongbo; Ozturk, Mustafa; Demirel, Pakize; Cakmak, Huseyin; Bolukbas, Basar; Caliskan, Deniz; Ozbay, Ekmel

2011-01-01

The Al x In 1−x N barrier high electron mobility transistor (HEMT) structure has been optimized with varied barrier composition and thickness grown by metalorganic chemical vapor deposition. After optimization, a transistor structure comprising a 7 nm thick nearly lattice-matched Al 0.83 In 0.17 N barrier exhibits a sheet electron density of 2.0 × 10 13 cm −2 with a high electron mobility of 1540 cm 2 V −1 s −1 . An Al 0.83 In 0.17 N barrier HEMT device with 1 µm gate length provides a current density of 1.0 A mm −1 at V GS = 0 V and an extrinsic transconductance of 242 mS mm −1 , which are remarkably improved compared to that of a conventional Al 0.3 Ga 0.7 N barrier HEMT. To investigate the thermal stability of the HEMT epi-structures, post-growth annealing experiments up to 800 °C have been applied to Al 0.83 In 0.17 N and Al 0.3 Ga 0.7 N barrier heterostructures. As expected, the electrical properties of an Al 0.83 In 0.17 N barrier HEMT structure showed less stability than that of an Al 0.3 Ga 0.7 N barrier HEMT to the thermal annealing. The structural properties of Al 0.83 In 0.17 N/GaN also showed more evidence for decomposition than that of the Al 0.3 Ga 0.7 N/GaN structure after 800 °C post-annealing

Development of an U and Pu recovery process by molten salt electrorefining. Behavior of U and Pu at simultaneous recoveries into liquid cadmium cathodes

International Nuclear Information System (INIS)

Uozumi, Koichi; Kato, Tetsuya; Iizuka, Masatoshi; Inoue, Tadashi; Iwai, Takashi; Shirai, Osamu; Arai, Yasuo

2003-01-01

In order to study behaviors of U and Pu at simultaneous recoveries into liquid cadmium cathodes (LCCs) in the electrorefining of pyrometallurgical reprocessing, several experiments were conducted to recover U and Pu into LCCs at different U/Pu ratios in the salt phase. The major results were as follows: (1) The weight ratios of U and Pu in 120 g LCCs reached 10 wt.% (the tentative target), with current efficiencies higher than 80 %. (2) Under the conditions of U/Pu ratios in the initial salt phase less than 1/4.3, the amounts of recovered U and Pu were proportional to the passed electric charges, with the separation factors of U to Pu (= (U/Pu ration in the recovered product)/(U/Pu ratio in the salt)) between 1.2 and 2.0. (3) On the other hand, under the condition of U/Pu ratio in the initial salt phase at 1/1.73, only U was recovered into the LCC after the saturation of LCC with U and Pu. Accordingly, there will be a threshold in the U/Pu ratio of the salt phase for the simultaneous recovery of U and Pu. (4) Am showed a similar behavior to Pu. The separation factors of Am to Pu (=(AM/Pu ratio in the recovered product)/(Am/Pu ratio in the salt)) was 0.78, which means that Am is co-recovered with Pu into LCC. (author)

Deposition of Pu-239 in human bodies

International Nuclear Information System (INIS)

Okabayashi, Hiroyuki

1976-01-01

It is known that plutonium produced by nuclear explosion tests has been widely dispersed on all over the earth and Pu-238 generated by the ''Accident of SNAP-9A'' in 1964 has been disposed into the atmosphere. These Pu are gradually falling down on the earth and taken into the human body through inhalation and ingestion. The measurements on the concentrations of Pu in bones and other various organs of Japanese population have been carried out. The results reveal that the concentrations of Pu in bones has a trend to be gradually increasing since 1962 and seems to be saturated at about 1970. The concentrations of Pu in bones sampled in 1971 are, in average, in the level of 4fCi per gram of wet samples and those in other organs (lung, liver, spleen, kidney, reproductive organs, etc.) sampled from 1963 to 1973 are in the level of 0.5-3.4 fCi per gram of wet tissues. Pu has been identified in the bones of fetus and infants and the averaged concentrations of placenta was 42.5 fCi. These may indicate that Pu would be transferred to the fetus through the placenta of mother. Some calculation has been attempted on the ratio of contributions through inhalation and ingestion to the body content of Pu, by using the formula for the scheme of metabolism of Pu compound in the body recommended by I.C.R.P. and this revealed that the contribution through inhalation route seemed to be greater than the other for the accumulation of Pu in the body. (auth.)

Determination of Plutonium Activity Concentrations and 240Pu/239Pu Atom Ratios in Brown Algae (Fucus distichus) Collected from Amchitka Island, Alaska

International Nuclear Information System (INIS)

Hamilton, T F; Brown, T A; Marchetti, A A; Martinelli, R E; Kehl, S R

2005-01-01

Plutonium-239 ( 239 Pu) and plutonium-240 ( 240 Pu) activity concentrations and 240 Pu/ 239 Pu atom ratios are reported for Brown Algae (Fucus distichus) collected from the littoral zone of Amchitka Island (Alaska) and at a control site on the Alaskan peninsula. Plutonium isotope measurements were performed in replicate using Accelerator Mass Spectrometry (AMS). The average 240 Pu/ 239 Pu atom ratio observed in dried Fucus d. collected from Amchitka Island was 0.227 ± 0.007 (n=5) and compares with the expected 240 Pu/ 239 Pu atom ratio in integrated worldwide fallout deposition in the Northern Hemisphere of 0.1805 ± 0.0057 (Cooper et al., 2000). In general, the characteristically high 240 Pu/ 239 Pu content of Fucus d. analyzed in this study appear to indicate the presence of a discernible basin-wide secondary source of plutonium entering the marine environment. Of interest to the study of plutonium source terms within the Pacific basin are reports of elevated 240 Pu/ 239 Pu atom ratios in fallout debris from high-yield atmospheric nuclear tests conducted in the Marshall Islands during the 1950s (Diamond et al., 1960), the wide range of 240 Pu/ 239 Pu atom ratio values (0.19 to 0.34) observed in sea water, sediments, coral and other environmental media from the North Pacific Ocean (Hirose et al., 1992; Buesseler, 1997) and updated estimates of the relative contributions of close-in and intermediate fallout deposition on oceanic inventories of radionuclidies, especially in the Northern Pacific Ocean (Hamilton, 2004)

AMNESTY IN THE NIGER DELTA: VERTICAL MOVEMENT ...

African Journals Online (AJOL)

OLAWUYI

federal government, the Niger Delta communities claim that they are entitled to ... instability, macroeconomic challenges, inconsistent policy regimes to ..... continues they cannot threaten the stability of the country nor affect its continued.

Determination of Pu in soil samples

International Nuclear Information System (INIS)

Torres C, C. O.; Hernandez M, H.; Romero G, E. T.; Vega C, H. R.

2016-10-01

The irreversible consequences of accidents occurring in nuclear plants and in nuclear fuel reprocessing sites are mainly the distribution of different radionuclides in different matrices such as the soil. The distribution in the superficial soil is related to the internal and external exposure to the radiation of the affected population. The internal contamination with radionuclides such as Pu is of great relevance to the nuclear forensic science, where is important to know the chemical and isotopic compositions of nuclear materials. The objective of this work is to optimize the radiochemical separation of plutonium (Pu) from soil samples and to determine their concentration. The soil samples were prepared using acid digestion assisted by microwave; purification of Pu was carried out with AG1X8 resin using ion exchange chromatography. Pu isotopes were measured using ICP-SFMS. In order to reduce the interference due to the presence of "2"3"8UH "+ in the samples, a solvent removal system (Apex) was used. In addition, the limit of detection and quantification of Pu was determined. It was found that the recovery efficiency of Pu in soil samples ranges from 70 to 93%. (Author)

Safety requirements for the Pu carriers

International Nuclear Information System (INIS)

Mishima, H.

1993-01-01

Ministry of Transport of Japan has now set about studying requirements for Pu carriers to ensure safety. It was first studied what the basic concept of safe carriage of Pu should be, and the basic ideas have been worked out. Next the requirements for the Pu carriers were studied based on the above. There are at present no international requirements of construction and equipment for the nuclear-material carriers, but MOT of Japan has so far required special construction and equipment for the nuclear-material carriers which carry a large amount of radioactive material, such as spent fuel or low level radioactive waste, corresponding to the level of the respective potential hazard. The requirements of construction and equipment of the Pu carriers have been established considering the difference in heat generation between Pu and spent fuel, physical protection, and so forth, in addition to the above basic concept. (J.P.N.)

Transmutation of 129I, 237Np, 238Pu, 239Pu, and 241Am using ...

Indian Academy of Sciences (India)

Results of transmutation studies of 129I, 237Np, 238Pu, 239Pu and 241Am are presented. Keywords. ... J Adam et al. Table 1. Samples properties for 0.7 and 1 GeV experiments. ..... If we suppose that this conclusion is true also for ratios in ...

Structural stability of (Pu1-xAmx)O2 (x=0.2;0.5;0.8) obtained by oxalate co-conversion

International Nuclear Information System (INIS)

Jankowiak, A.; Donnet, L.; Maillard, C.

2008-01-01

The EUROTRANS project investigates the transmutation of transuranium elements in dedicated reactors (ADS, FR). The study includes various subject areas: neutronics, physical properties, coolant type (sodium, lead, bismuth, helium), etc, and experimental work concerning the fabrication of minor actinide compounds for thermo-physical properties determination. For this program, the CEA was responsible for synthesizing three Pu 1-x Am x O 2 compounds with various Am and Pu content (x = 0.2, 0.5, 0.8). The selected synthesis route for the mixed Am and Pu oxide powder consists in actinides oxalates co-conversion. The purpose of the study was to determine by XRD the crystal structure and the lattice parameters change as a function of the time for each co-converted mixed oxides. After one year of experiment, although the lattice parameters significantly expanded, the compounds remained monophasic. The observations showed that the initial expansion rate and the a max stage value vary according to the Pu and Am content. (authors)

Optical properties of lattice matched In{sub x}Ga{sub 1-x}P{sub 1-y}N{sub y} heteroepitaxial layers on GaP

Energy Technology Data Exchange (ETDEWEB)

Imanishi, T.; Wakahara, A.; Kim, S.M.; Yonezu, H.; Furukawa, Y. [Department of Electrical and Electron Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 411-8580 (Japan)

2005-04-01

Optical constants and band structure of In{sub x}Ga{sub 1-x}P{sub 1-y}N{sub y} lattice matched to GaP (100) substrate are investigated. Nitrogen concentration in the film estimated by X-ray diffraction and X-ray photoelectron spectroscopy, was 1.4%, 1.8% and 3.5%. Refractive index and transition critical points E{sub 0} ({gamma}{sub v} to {gamma}{sub c}), E{sub 1} (L{sub v} to L{sub c}) and E{sub 2} (X{sub v} to X{sub c}) are evaluated by spectroscopic ellipsometry. When N composition increases from 1.4% to 3.5%, both photoluminescence (PL) peak energy, E{sub PL}, and E{sub 0} shift to lower energy, and the energy difference {delta}E=E{sub 0}-E{sub PL} decrease from 380 meV to 110 meV. The large red-sift of E{sub PL} from the E{sub 0} suggest that the luminescence is of defect-related luminescence, and crossover point of indirect band structure estimated by the extrapolation of N-composition dependence of {delta}E is estimated to be around in In{sub 0.1}Ga{sub 0.9}P{sub 0.96}N{sub 0.04}. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The remarkable stability of chimeric, sialic acid-derived alpha/delta-peptides in human blood plasma.

Science.gov (United States)

Saludes, Jonel P; Natarajan, Arutselvan; DeNardo, Sally J; Gervay-Hague, Jacquelyn

2010-05-01

Peptides are labile toward proteolytic enzymes, and structural modifications are often required to prolong their metabolic half-life and increase resistance. One modification is the incorporation of non-alpha-amino acids into the peptide to deter recognition by hydrolytic enzymes. We previously reported the synthesis of chimeric alpha/delta-peptides from glutamic acids (Glu) and the sialic acid derivative Neu2en. Conformational analyses revealed these constructs adopt secondary structures in water and may serve as conformational surrogates of polysialic acid. Polysialic acid is a tumor-associated polysaccharide and is correlated with cancer metastasis. Soluble polysialic acid is rapidly cleared from the blood limiting its potential for vaccine development. One motivation in developing structural surrogates of polysialic acid was to create constructs with increased bioavailability. Here, we report plasma stability profiles of Glu/Neu2en alpha/delta-peptides. DOTA was conjugated at the peptide N-termini by solid phase peptide synthesis, radiolabeled with (111)In, incubated in human blood plasma at 37 degrees C, and their degradation patterns monitored by cellulose acetate electrophoresis and radioactivity counting. Results indicate that these peptides exhibit a long half-life that is two- to three-orders of magnitude higher than natural alpha-peptides. These findings provide a viable platform for the synthesis of plasma stable, sialic acid-derived peptides that may find pharmaceutical application.

Preliminary results for complexation of Pu with humic acid

Energy Technology Data Exchange (ETDEWEB)

Guczi, J.; Szabo, G. [National Research Inst. for Radiobiology and Radiohygi ene, Budapest, H-1775 (Hungary)]. e-mail: guczi@hp.osski.hu; Reiller, P. [CEA, CE Sac lay, Nuclear Energy Division/DPC/SERC, Laboratoire de Speciation des Radionuclei des et des Molecules, F-91191 Gif-sue-Yvette (France); Bulman, R.A. [Radiation Protection Division Division, Health Protection Agency, Chilton, Didcot (United Kingdom); Geckeis, H. [FZK - Inst. fuer Nukleare Entsorgung, Karlsruhe (Germany)

2007-06-15

Interaction of plutonium with humic substances has been investigated by a batch method use of the surface bound humic acid from perchlorate solutions at pH 4-6. By using these novel solid phases, complexing capacities and interaction constants are obtained. The complexing behavior of plutonium is analyzed. Pu(IV)-humate conditional stability constants have been evaluated from data obtained from these experiments by using non-linear regression of binding isotherms. The results have been interpreted in terms of complexes of 1:1 stoichiometry.

Improved damp heat stability of Ga-Doped ZnO thin film by pretreatment of the polyethylene terephthalate substrate

Science.gov (United States)

Kim, B. B.; Seo, S. G.; Lim, Y. S.; Choi, H.-S.; Seo, W.-S.; Park, H.-H.

2013-09-01

A study on the damp heat stability of transparent conducting ZnO thin film grown on a polyethylene terephthalate substrate (PET) is reported. By thermal annealing of the PET substrate at 100°C with Ar flow in a vacuum chamber prior to the sputtering growth of Ga-doped ZnO (GZO) thin film, significantly enhanced damp heat stability was achieved at 60°C with a 90% relative humidity. Electrical and structural characterizations of the GZO thin films were carried out and the effects of the pretreatment on the improved damp heat stability are discussed.

ZPR-6 assembly 7 high {sup 240}Pu core experiments : a fast reactor core with mixed (Pu,U)-oxide fuel and a centeral high{sup 240}Pu zone.

Energy Technology Data Exchange (ETDEWEB)

Lell, R. M.; Morman, J. A.; Schaefer, R.W.; McKnight, R.D.; Nuclear Engineering Division

2009-02-23

ZPR-6 Assembly 7 (ZPR-6/7) encompasses a series of experiments performed at the ZPR-6 facility at Argonne National Laboratory in 1970 and 1971 as part of the Demonstration Reactor Benchmark Program (Reference 1). Assembly 7 simulated a large sodium-cooled LMFBR with mixed oxide fuel, depleted uranium radial and axial blankets, and a core H/D near unity. ZPR-6/7 was designed to test fast reactor physics data and methods, so configurations in the Assembly 7 program were as simple as possible in terms of geometry and composition. ZPR-6/7 had a very uniform core assembled from small plates of depleted uranium, sodium, iron oxide, U{sub 3}O{sub 8} and Pu-U-Mo alloy loaded into stainless steel drawers. The steel drawers were placed in square stainless steel tubes in the two halves of a split table machine. ZPR-6/7 had a simple, symmetric core unit cell whose neutronic characteristics were dominated by plutonium and {sup 238}U. The core was surrounded by thick radial and axial regions of depleted uranium to simulate radial and axial blankets and to isolate the core from the surrounding room. The ZPR-6/7 program encompassed 139 separate core loadings which include the initial approach to critical and all subsequent core loading changes required to perform specific experiments and measurements. In this context a loading refers to a particular configuration of fueled drawers, radial blanket drawers and experimental equipment (if present) in the matrix of steel tubes. Two principal core configurations were established. The uniform core (Loadings 1-84) had a relatively uniform core composition. The high {sup 240}Pu core (Loadings 85-139) was a variant on the uniform core. The plutonium in the Pu-U-Mo fuel plates in the uniform core contains 11% {sup 240}Pu. In the high {sup 240}Pu core, all Pu-U-Mo plates in the inner core region (central 61 matrix locations per half of the split table machine) were replaced by Pu-U-Mo plates containing 27% {sup 240}Pu in the plutonium

Distribution of 238Pu and 239240Pu in aquatic macrophytes from a midwestern watershed

International Nuclear Information System (INIS)

Wayman, C.W.; Bartelt, G.E.; Alberts, J.J.

1977-01-01

Aquatic macrophytes were collected in the Great Miami River, Ohio, above and below Miamisburg and in the canal and ponds, near the Mound Laboratory, which contain sediments of a high activity (approximately 10 3 to 10 6 times) relative to the river sediments. Macrophytes collected in the river below Miamisburg have higher activities of 238 Pu than those collected from above the city. Macrophytes from the canal and ponds contain high specific activities of 238 Pu and 239 , 240 Pu with the exception of cattails grown in the ponds. Concentration factors are reported and discussed with reference to possible modes of plutonium accumulation and distribution within the plants

Neutron inelastic-scattering cross sections of 232Th, 233U, 235U, 238U, 239Pu and 240Pu

International Nuclear Information System (INIS)

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

1982-01-01

Differential-neutron-emission cross sections of 232 Th, 233 U, 235 U, 238 U, 239 Pu and 240 Pu are measured between approx. = 1.0 and 3.5 MeV with the angle and magnitude detail needed to provide angle-integrated emission cross sections to approx. 232 Th, 233 U, 235 U and 238 U inelastic-scattering values, poor agreement is observed for 240 Pu, and a serious discrepancy exists in the case of 239 Pu

Measurement of oxygen chemical diffusion in PuO2-x and analysis of oxygen diffusion in PuO2-x and (Pu,U)O2-x

International Nuclear Information System (INIS)

Kato, Masato; Uchida, Teppei; Sunaoshi, Takeo

2013-01-01

Oxygen chemical diffusion in PuO 2-x was investigated in the temperature range of 1473-1873 K by thermogravimetry as functions of oxygen-to-metal (O/M) ratios and temperatures. The oxygen chemical diffusion coefficients, D were determined assuming that the reduction curves were dominated by a diffusion process. The O/M ratio and Pu content dependence on the chemical diffusion coefficients were evaluated. The chemical diffusion coefficient had its minimum value at around O/M=1.98 and decreased with increasing Pu content in (U,Pu)O 2-x . The self-diffusion coefficients were evaluated. A model for describing the relationship among O/M ratio, oxygen chemical diffusion, and self-diffusion was proposed based on defect chemistry. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Determination of 239Pu/240Pu isotopic ratio by high resolution alpha-particle spectrometry

International Nuclear Information System (INIS)

Amoudry, F.; Burger, P.

1983-05-01

The development of passivated ion-implanted silicon detectors and of very thin alpha-particle sources improves the resolution of alpha-particle spectra and allows to separate energy pics up to now unseparate. The 239 Pu/ 240 Pu isotopic ratio of a mixture has been measured using the alpha spectrometry deconvolution code DEMO [fr

Reactivity and interdiffusion of alternative SOFC cathodes with yttria stabilized zirconia, gadolinia doped ceria and doped lanthanum gallate solid electrolytes

Energy Technology Data Exchange (ETDEWEB)

Kostogloudis, G.C.; Tsiniarakis, G.; Riza, F.; Ftikos, C. [National Tech. Univ. of Athens (Greece)

2000-07-01

The chemical compatibility between the cathode composition Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} and the electrolyte compositions yttria stabilized zirconia (YSZ), Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} (CGO) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.9}Mg{sub 0.1}O{sub 3-{delta}} (LSGM) was investigated. Also, the influence of the substitution of Al for Fe on the reactivity of the cathode with YSZ was examined. All oxides were single-phase materials except for LSGM, which contained two additional phases, namely LaSrGa{sub 3}O{sub 7} and LaSrGaO{sub 4}. Two types of experiments were performed: (a) reactivity experiments by XRD in cathode/electrolyte powder mixtures and (b) diffusion experiments by SEM/EDX analysis in cathode/electrolyte double-layer pellets. Pr{sub 2}Zr{sub 2}O{sub 7}, SrZrO{sub 3} and CoFe{sub 2}O{sub 4} were formed by the interaction of the cathode materials with YSZ. Substitution by Al at the B-site of the perovskite cathode led to a decrease of its reactivity with YSZ. No reaction products were formed for powder mixtures of Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} and CGO or LSGM electrolytes. High Co and Fe diffusion into LSGM was identified. Pr, La and Ga show a smaller tendency for diffusion. The diffusion of transition metal cations into LSGM electrolyte caused the destabilisation and disappearance of the second phases in the interdiffusion zone. (orig.)

Characterization of a Pu-bearing zirconolite-rich synroc

International Nuclear Information System (INIS)

Buck, E.C.; Ebbinghaus, B.; Bakel, A.J.; Bates, J.K.

1996-01-01

A titanate-based ceramic waste form, rich in phases structurally related to zirconolite (CaZrTi 2 O 7 ), is being developed as a possible method for immobilizing excess plutonium from dismantled nuclear weapons. As part of this program, Lawrence Livermore National Laboratory (LLNL) produced several ceramics that were then characterized at Argonne National Laboratory (ANL). The plutonium- loaded ceramic was found to contain a Pu-Gd zirconolite phase but also contained plutonium titanates, Gd-polymignyte, and a series of other phases. In addition, much of the Pu was remained as PuO 2- x . The Pu oxidation state in the zirconolite was determined to be mainly Pu 4+ , although some Pu 3+ was believed to be present

Nitridation of U and Pu recovered in liquid Cd cathode by molten salt electrorefining of (U,Pu)N

Energy Technology Data Exchange (ETDEWEB)

Satoh, Takumi; Iwai, Takashi; Arai, Yasuo [Japan Atomic Energy Agency (Japan)

2009-06-15

Solid solutions of actinide mono-nitrides have been proposed as a candidate fuel of the accelerator-driven system (ADS) and Gen.IV-type fast reactors because the thermal conductivity and metal density are higher than those of actinide oxides and also they have high melting temperature. Pyrochemical process has several advantages over conventional wet process in treating of spent nitride fuel. One of the key technologies of the pyrochemical reprocessing of nitride fuel is the formation of the nitrides from actinides in the liquid Cd cathode. The nitridation-distillation combined method was developed and has been adopted to convert the actinides to the nitrides. In this method, the nitridation of actinides and the distillation of Cd occurred simultaneously by heating the actinide-Cd alloys in N{sub 2} gas stream. In the present study, the nitride formation behavior of U and Pu recovered in Cd cathode by molten salt electrorefining of (U,Pu)N was experimentally investigated. In addition, the nitride pellet was prepared form the powder obtained by the nitridation of U and Pu recovered in Cd cathode. (U,Pu)N (PuN = 80 mol %) was used as the starting material in the experiment. Molten salt electrorefining of (U,Pu)N pellet was carried out in the LiCl-KCl eutectic salt with 1.2 wt% PuCl{sub 3} and 0.3 wt% UCl{sub 3} of about 110 g at the constant anodic potential of -0.60 to -0.55 V vs. Ag/AgCl for about 9 hours at 773 K. After the electrorefining, about 42 % of U and Pu in the starting (U,Pu)N pellet was dissolved at the anode and recovered into the liquid Cd cathode. The recovered U-Pu-Cd alloy was heated in an alumina crucible at 973 K for 10 hours under N{sub 2} gas (99.999 %) stream (0.015 L/min). Fine black powder was recovered after heating the U-Pu-Cd alloy. The powder was identified as the single phase solid solution of (U,Pu)N by the XRD analysis. After milling in the agate mortar for 1 hour, the powder was compacted into green pellet under a pressure of about

Risk estimates for lung tumors from inhaled 239PuO2, 238PuO2, and /sup 239Pu/(NO3)4 in beagle dogs

International Nuclear Information System (INIS)

Dagle, G.E.; Park, J.F.; Gilbert, E.S.; Weller, R.E.

1988-06-01

Lung-cancer risks are being studied in beagle dogs given single exposures to aerosols of 239 PuO 2 , 238 PuO 2 , or 239 Pu(NO 3 ) 4 . A major objective of these studies is to examine the risk of lung cancer relative to the specific activity of the radionuclide, rate of dose accumulation due to differences in solubilities of the radionuclides, and the presence of competing risk from extrapulmonary lesions. Dose-response relationships were studied for the three groups of dogs, with analyses specifically designed to evaluate differences in response. Based on estimated cumulative dose to the lung, risks were found to differ significantly among the radionuclides; they were highest for 239 Pu(NO 3 ) 4 and lowest for 238 PuO 2 . A model in which the risk was assumed to be a pure quadratic function of dose fit the data much better than a pure linear model. Currently, all three groups of dogs can be compared only to 10 years after exposure. However, it is apparent that the average cumulative dose to the lung may not be an adequate predictor of lung-cancer risk for different isotopic and physicochemical forms of plutonium. 13 refs., 2 tabs

Stability of AlGaN/GaN heterostructures after hydrogen plasma treatment

Czech Academy of Sciences Publication Activity Database

Babchenko, O.; Dzuba, J.; Lalinský, T.; Vojs, M.; Vincze, A.; Ižák, Tibor; Vanko, G.

2017-01-01

Roč. 395, Feb (2017), s. 92-97 ISSN 0169-4332 R&D Projects: GA ČR(CZ) GP14-16549P Grant - others:AV ČR(CZ) SAV-16-02 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : AIGaN/GaN heterostructure * hydrogen plasma * SIMS * TLM * HEMT Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.387, year: 2016

Artificial radioactivity and marine environment. Study of 238Pu, 239Pu+240Pu, 241Pu and 241Am in the Mediterranean sea

International Nuclear Information System (INIS)

Ballestra, Serge.

1980-10-01

This paper is in two parts. Part one is about the methods for analyzing transuranium elements particularly the development of an analytical process for plutonium and for perfecting an Americium analyzing method, capable of treating samples of 200 litres of sea water, 100 grams of sediment and 100 grams of biological matter. Part two concerns the in situ determinations carried out within the scope of the study on the distribution and behaviour of transuranium elements in the Mediterranean sea. The high sea studies concerned the effects of atmospheric fall out and the vertical distribution of Pu and Am. Studies along the coasts enabled a quantitative study to be made of the contribution of rivers to the Mediterranean and to study the distribution of Pu along the French Mediterranean coast line [fr

Molecular gated-AlGaN/GaN high electron mobility transistor for pH detection.

Science.gov (United States)

Ding, Xiangzhen; Yang, Shuai; Miao, Bin; Gu, Le; Gu, Zhiqi; Zhang, Jian; Wu, Baojun; Wang, Hong; Wu, Dongmin; Li, Jiadong

2018-04-18

A molecular gated-AlGaN/GaN high electron mobility transistor has been developed for pH detection. The sensing surface of the sensor was modified with 3-aminopropyltriethoxysilane to provide amphoteric amine groups, which would play the role of receptors for pH detection. On modification with 3-aminopropyltriethoxysilane, the transistor exhibits good chemical stability in hydrochloric acid solution and is sensitive for pH detection. Thus, our molecular gated-AlGaN/GaN high electron mobility transistor acheived good electrical performances such as chemical stability (remained stable in hydrochloric acid solution), good sensitivity (37.17 μA/pH) and low hysteresis. The results indicate a promising future for high-quality sensors for pH detection.

Delta phase plutonium and its alloys with III B elements: a microscopic study; Etude du plutonium en phase {delta} et de ses alliages avec les elements de la colonne IIIB

Energy Technology Data Exchange (ETDEWEB)

Bouchet, J

2001-07-01

The plutonium belongs to the actinides where it occupies a crucial place. In the actinide series the competition between the itinerant and local character of the f-electrons is responsible of its unique properties. The series can be divided into two sub-series: the light ({sub 90}Th-{sub 94}Pu) and the heavy ({sub 95}Am and beyond) actinides with very different characteristics. The volume behavior of the light actinides is very similar to the one found for the transitions metals with a parabolic decrease of the volume as a function of atomic number. This trend can be explained by the itinerant character of the 5 f electrons which participate to the chemical bonding, and thus the light actinides are considered to form a 5 f transition series. The density functional theory in the local-density approximation (LDA) gives a good description of the ground state of the light actinides in agreement with experiment and a simple Friedel model can explain the parabolic decrease of the volumes. As for heavy actinides, the pattern is reversed: 5 f electrons are localized. This picture places plutonium as the link between the two series, at the transition from delocalized to localized states. The density functional theory within the local density approximation is a very crude approximation for these systems where the on-site interaction between f electrons is strong enough to overcome the kinetic energy. Equilibrium properties for the {delta}-phase of Pu have been calculated. Taking into account strong electron correlations in the 5 f shell, we show how the equilibrium volume and the bulk modulus are improved in comparison to previous results using the local density approximation (LDA) or the generalized gradient approximation (GGA). In addition, an augmentation of the orbital moment is observed due to the respect of Hund's rules, reducing the total magnetic moment. The stability of the {delta}-phase is explored and for the first time a positive value for the tetragonal shear

Delta phase plutonium and its alloys with III B elements: a microscopic study; Etude du plutonium en phase {delta} et de ses alliages avec les elements de la colonne IIIB

Energy Technology Data Exchange (ETDEWEB)

Bouchet, J

2001-07-01

The plutonium belongs to the actinides where it occupies a crucial place. In the actinide series the competition between the itinerant and local character of the f-electrons is responsible of its unique properties. The series can be divided into two sub-series: the light ({sub 90}Th-{sub 94}Pu) and the heavy ({sub 95}Am and beyond) actinides with very different characteristics. The volume behavior of the light actinides is very similar to the one found for the transitions metals with a parabolic decrease of the volume as a function of atomic number. This trend can be explained by the itinerant character of the 5 f electrons which participate to the chemical bonding, and thus the light actinides are considered to form a 5 f transition series. The density functional theory in the local-density approximation (LDA) gives a good description of the ground state of the light actinides in agreement with experiment and a simple Friedel model can explain the parabolic decrease of the volumes. As for heavy actinides, the pattern is reversed: 5 f electrons are localized. This picture places plutonium as the link between the two series, at the transition from delocalized to localized states. The density functional theory within the local density approximation is a very crude approximation for these systems where the on-site interaction between f electrons is strong enough to overcome the kinetic energy. Equilibrium properties for the {delta}-phase of Pu have been calculated. Taking into account strong electron correlations in the 5 f shell, we show how the equilibrium volume and the bulk modulus are improved in comparison to previous results using the local density approximation (LDA) or the generalized gradient approximation (GGA). In addition, an augmentation of the orbital moment is observed due to the respect of Hund's rules, reducing the total magnetic moment. The stability of the {delta}-phase is explored and for the first time a positive value for the tetragonal

GaAs detectors with an ultra-thin Schottky contact for spectrometry of charged particles

Energy Technology Data Exchange (ETDEWEB)

Chernykh, S.V., E-mail: chsv_84@mail.ru [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Chernykh, A.V. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Didenko, S.I.; Baryshnikov, F.M. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Burtebayev, N. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan); Britvich, G.I. [Institute of High Energy Physics, Protvino, Moscow region (Russian Federation); Chubenko, A.P. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Guly, V.G.; Glybin, Yu.N. [LLC “SNIIP Plus”, Moscow (Russian Federation); Zholdybayev, T.K.; Burtebayeva, J.T.; Nassurlla, M. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan)

2017-02-11

For the first time, samples of particle detectors based on high-purity GaAs epilayers with an active area of 25 and 80 mm{sup 2} and an ultra-thin Pt Schottky barrier were fabricated for use in the spectrometry of charged particles and their operating characteristics were studied. The obtained FWHM of 14.2 (for 25 mm{sup 2} detector) and 15.5 keV (for 80 mm{sup 2} detector) on the 5.499 MeV line of {sup 238}Pu is at the level of silicon spectrometric detectors. It was found that the main component that determines the energy resolution of the detector is a fluctuation in the number of collected electron–hole pairs. This allows us to state that the obtained energy resolution is close to the limit for VPE GaAs. - Highlights: • VPE GaAs particle detectors with an active area of 25 and 80 mm{sup 2} were fabricated. • 120 Å ultra-thin Pt Schottky barrier was used as a rectifying contact. • The obtained FWHM of 14.2 keV ({sup 238}Pu) is at the level of Si spectrometric detectors. • Various components of the total energy resolution were analyzed. • It was shown that obtained energy resolution is close to its limit for VPE GaAs.

PU-ICE Summary Information.

Energy Technology Data Exchange (ETDEWEB)

Moore, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-05-01

The Generator Knowledge Report for the Plutonium Isentropic Compression Experiment Containment Systems (GK Report) provides information for the Plutonium Isentropic Compression Experiment (Pu- ICE) program to support waste management and characterization efforts. Attachment 3-18 presents generator knowledge (GK) information specific to the eighteenth Pu-ICE conducted in August 2015, also known as ‘Shot 18 (Aug 2015) and Pu-ICE Z-2841 (1).’ Shot 18 (Aug 2015) was generated on August 28, 2015 (1). Calculations based on the isotopic content of Shot 18 (Aug 2015) and the measured mass of the containment system demonstrate the post-shot containment system is low-level waste (LLW). Therefore, this containment system will be managed at Sandia National Laboratory/New Mexico (SNL/NM) as LLW. Attachment 3-18 provides documentation of the TRU concentration and documents the concentration of any hazardous constituents.

Pu Denaturing by Transmutation of MA in FBR Multi-cycle

Energy Technology Data Exchange (ETDEWEB)

Meiliza, Yoshitalia; Saito, Masaki; Sagara, Hiroshi [Tokyo Institute of Technology, 2-12-1-N1-1 Ookayama, Meguro-ku, Tokyo, 1528550 (Japan)

2009-06-15

Pu accumulation and its recycling is important in the term of energy resources, however one of the most sensitive issues is non-proliferation in the future fuel cycle based on fast breeder reactor (FBR). The present paper utilizes Protected Pu Production (P{sup 3}) concept for the production of {sup 238}Pu and {sup 242}Pu by Minor Actinides (MA) transmutation to enhance the proliferation resistance of Pu in the fuel. Increase in the {sup 238}Pu and {sup 242}Pu isotopic fraction creates a high rate of internal heat generation by alpha decay (DH) and/or a high neutron source of spontaneous fission (SFN) in Pu that would be encountered during manufacturing and maintaining of nuclear explosive device. The feasibility of denaturing of Pu by MA transmutation in medium size FBR has been studied from the viewpoint of even-mass number Pu accumulation during multi-cycle of Pu and MA. The proliferation resistance property of Pu is also evaluated based on the specific decay heat and spontaneous fission neutron, compared with the reference criteria. In present paper, the P{sup 3} technology based on multi-recycled Pu and MA is compared with the conventional technology based on multi-recycled Pu only. The detail of mass balance behavior is, however, beyond the scope of the present paper. (authors)

Pu and Am determination in the environment method development

International Nuclear Information System (INIS)

Afonin, M.; Simonoff, M.; Donard, O.; Michel, H.; Ardisson, G.

2002-01-01

A few articles were published in the recent years regarding the application of ICP MS HR to the determination of ultratrace Pu in the environment. Si removal was not applied in recent publications. It is well known from marine biology that some microorganisms use Si derivatives in their metabolism. This implies that important amounts of Pu will not be dissolved and instead will rest in the solid residue. In our work we chose a combination of methods from EML-300 Handbook: Pu-02-RC Plutonium in Soil Samples, Pu-03-RC Plutonium in Soil Residue - Total Dissolution Method, Pu-11-RC Plutonium Purification - Ion Exchange Technique, Pu-12-RC Plutonium and/or Americium in Soil or Sediments. A high resolution inductively coupled plasma mass spectrometric method was developed for the determination of Am and the 240 Pu/ 239 Pu isotope ratio. The total plutonium concentrations ( 239+240 Pu) measured in environmental samples by this method were in good agreement with recommended data obtained from alpha-spectrometry. A reduction in the time of analysis over 33% was achieved

Spatial and temporal variations of plutonium isotopes (238Pu and 239,240Pu) in sediments off the Rhone River mouth (NW Mediterranean)

International Nuclear Information System (INIS)

Lansard, B.; Charmasson, S.; Gasco, C.; Anton, M.P.; Grenz, C.; Arnaud, M.

2007-01-01

The dispersion and fate of the Rhone River inputs to the Gulf of Lions (Northwestern Mediterranean Sea) have been studied through the spatial and temporal distributions of plutonium isotopes in continental shelf sediments. Plutonium isotopes ( 238 Pu and 239,240 Pu) are appropriate tracers to follow the dispersion of particulate matter due both to their high affinity for particles and their long half-lives. In the Rhone River valley, plutonium isotopes originate from both the weathering of the catchment basin contaminated by global atmospheric fallout, and the liquid effluents released from the Marcoule reprocessing plant since 1961. This work presents a first detailed study on 238 Pu and 239,240 Pu distributions in sediments from the Rhone prodelta to the adjacent continental shelf, since the decommissioning of Marcoule in 1997. The vertical distribution of Pu isotopes has been analysed in a 4.75 m long core sampled in 2001 at the Rhone mouth. Despite this length, plutonium is found at the last 10 cm, manifesting the high sedimentation rate of the prodeltaic area and its ability for trapping fine-grained sediments and associated contaminants. The highest 238 Pu and 239,240 Pu concentrations reached 1.26 and 5.97 Bq kg -1 respectively and were found within the layer 280-290 cm. The 238 Pu/ 239,240 Pu activity ratios (AR) demonstrated an efficient and huge trapping of the Pu isotopes derived from Marcoule. The fresh sediments, located on the top of the core, show lower plutonium activity concentrations and lower 238 Pu/ 239,240 Pu ratios. This decrease is in close relation with the shut down of the Marcoule reprocessing plant in 1997. In 2001, plutonium isotopes were also analysed in 21 surface sediments located offshore and concentrations ranged from 0.03 to 0.17 Bq kg -1 for 238 Pu and from 0.33 to 1.72 Bq kg -1 for 239,240 Pu. The 238 Pu/ 239,240 Pu AR ranged from 0.24 close to the river mouth to 0.06 southwards, indicating the decreasing influence of the

Structures and potential energy functions of Pu3 molecule

International Nuclear Information System (INIS)

Meng Daqiao; Jiang Gang; Liu Xiaoya; Luo Deli; Zhu Zhenghe

2001-01-01

Density functional (B3LYP) method with relativistic effective core potential (RECP) has been used to optimize the structures of Pu 2 and Pu 3 molecules. The results show that the ground states of Pu 2 and Pu 3 molecules are of D ∞h and D 3h symmetry, and of 13 and 19 fold, respectively. The spectral constants of Pu 2 , ω e = 52.3845 cm -1 and ω e x e = 0.0201 cm -1 , and the harmonic frequencies of Pu 3 , ν 1 = 56.9007 cm -1 , ν 2 = 57.1816 cm - '1 and ν 3 = 64.0785 cm -1 , have also been obtained on the B3LYP/RECP level. The potential energy functions of Pu 2 and Pu 3 have been derived, for the first time so far as known, from normal equation fitting and the many-body expansion theory

On the fission probability for 235U, 239Pu and 241Pu

International Nuclear Information System (INIS)

Benzi, V.; Maino, G.; Menapace, E.

1978-01-01

An evaluation of the GAMMAsub(n)/GAMMAsub(f) ratio for the 236 U, 240 Pu and 242 Pu compound nuclei is carried out. First chance and second chance fission cross sections are estimated from the ''evaporation'' model; particularly, a largely increasing trend was found for the first chance fission cross section above the (n,n'f) process threshold. The GAMMAsub(n)/GAMMAsub(f) ratios for the analyzed nuclei show a bump-like structure, that seems to be in agreement with the theoretical predictions reported in literature

Many-electron effect in the Si K-LL resonant Auger-electron spectroscopy spectra of the Si delta layer in GaAs

International Nuclear Information System (INIS)

Ohno, Masahide

2006-01-01

The Si K-LL resonant Auger-electron spectroscopy (RAES) spectra of silicon delta dopped layers in GaAs with very thin capping layers show both normal Auger decay and resonant Auger decay, when the core-level electron is excited to the conduction band. The resonant Auger peak kinetic energy (KE) shows no dispersion with photon energy, except when excited by the highest energy photons [M.D. Jackson, J.M.C. Thornton, D. Lewis, A. Robinson, M. Fahy, A. Aviary, P. Weightman, Phys. Rev. B71 (2005) 075313]. The RAES spectra are analyzed using a many-body theory. The presence of resonant Auger decay and no dispersion of resonant Auger peak KE with photon energy is explained in terms of the relaxation of a metastable excited core-hole state to a stable one on the time scale of core-hole decay. The excited electron in the conduction band either delocalizes rapidly leaving the ionized Si to decay by a normal Auger decay or drops to a state localized in the Si delta layer before the core-hole decays so that the RAES spectrum has both normal Auger decay and resonant Auger decay. As a result of the relaxation, the resonant Auger peak KE does not show any dispersion with photon energy. The variations with photon energy of the normal or resonant Auger peak intensity, KE, and width are explained in a consistent manner by a many-body theory

Radiation protection problems with sealed Pu radiation sources

International Nuclear Information System (INIS)

Naumann, M.; Wels, C.

1982-01-01

A brief outline of the production methods and most important properties of Pu-238 and Pu-239 is given, followed by an overview of possibilities for utilizing the different types of radiation emitted, a description of problems involved in the safe handling of Pu radiation sources, and an assessment of the design principles for Pu-containing alpha, photon, neutron and energy sources from the radiation protection point of view. (author)

Dosimetry of 239Pu in dogs that inhaled monodisperse aerosols of 239PuO2

International Nuclear Information System (INIS)

Guilmette, R.A.; Muggenburg, B.A.; Hahn, F.F.; Mewhinney, J.A.; Seiler, F.A.; Boecker, B.B.; McClellan, R.O.

1987-01-01

Existing data from human exposure cases and experimental animal studies on the fate and dosimetry of inhaled insoluble Pu particles are inadequate to provide a comprehensive description and evaluation of the tissues at risk from the alpha radiations of Pu. To improve our knowledge of the dosimetry of inhaled insoluble 239 PuO 2 , this paper describes the uptake and retention of 239 Pu in the tissues of dogs that received single inhalation exposures to monodisperse aerosols of 239 PuO 2 . These data include times through 3 years after exposure. Using analytical functions fitted to each tissue data set, 1100-day radiation doses were calculated for lung, liver, skeleton, kidney, spleen, and tracheobronchial, mediastinal, sternal, hepatic, mandibular, and retropharyngeal lymph nodes. The dosimetry results suggest that the lung and lymph nodes associated with lymphatic drainage of the respiratory tract are the principal sites of alpha irradiation. However, the doses for the different respiratory tract lymph nodes vary by a factor of 2000, suggesting that assuming equivalent doses to respiratory tract lymph nodes is not appropriate. Other tissues receive radiation doses also but at levels one to three orders of magnitude less than the lung. Particle size dependence on uptake and retention was noted for the skeleton, mediastinal lymph nodes, hepatic lymph nodes, retropharyngeal lymph nodes, and mandibular lymph nodes

Epitaxial growth of In-rich InGaN on yttria-stabilized zirconia and its application to metal–insulator–semiconductor field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Atsushi; Lye, Khe Shin; Ueno, Kohei [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); Ohta, Jitsuo [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); PRESTO, Japan Science and Technology Agency, Saitama 332-0012 (Japan); Fujioka, Hiroshi, E-mail: hfujioka@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); ACCEL, Japan Science and Technology Agency, Tokyo 102-0076 (Japan)

2016-08-28

We grew In-rich In{sub x}Ga{sub 1-x}N films on yttria-stabilized zirconia (YSZ) substrates at low temperatures by pulsed sputtering deposition. It was found that single-crystal In{sub x}Ga{sub 1-x}N (0.63 ≤ x ≤ 0.82) films can be prepared without significant compositional fluctuations at growth temperatures below 500 °C. It was also found that the electrical properties of InGaN are strongly dependent on In composition, growth temperature, and film polarity. N-channel operation of the metal–insulator–semiconductor field-effect transistor (MISFET) with an ultrathin InGaN channel on the YSZ substrates was successfully demonstrated. These results indicate that an InGaN-based MISFET is a promising device for next-generation high-speed electronics.

Comparison of GaP and PH{sub 3} as dopant sources for STM-based device fabrication

Energy Technology Data Exchange (ETDEWEB)

Goh, Kuan Eng Johnson [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Oberbeck, L [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Butcher, M J [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Curson, N J [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Ruess, F J [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia); Simmons, M Y [Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia)

2007-02-14

We present a comparative study of the use of a GaP solid source as an alternative to gaseous PH{sub 3} for controlled phosphorus {delta}-doping of lithographic patterns on H:Si(001) fabricated by scanning tunnelling microscopy (STM). Whilst our electrical studies show that P {delta}-doping of Si with the GaP solid source and gaseous PH{sub 3} result in essentially the same electrical characteristics, our STM studies reveal that P{sub 2} molecules from the GaP source exhibit a lower selectivity between bare Si(001) and H:Si(001) compared to PH{sub 3} molecules. We discuss the significance of our findings in the context of fabricating nanoscale P dopant devices in Si using STM-based lithography.

Activity and stability of a <GaPON>> oxynitride in the dehydrogenation of isobutane

Energy Technology Data Exchange (ETDEWEB)

Delsarte, S.; Grange, P. [Univ. Catholique de Louvain (Belgium). Unite de Catalyse et Chimie des Materiaux Divises; Laurent, Y. [Lab. de Chimie des Materiaux, Univ. de Rennes 1, Rennes (France)

2000-07-01

Isobutane dehydrogenation was studied on platinum impregnated mixed aluminium gallium phosphorus oxide and oxynitride, in a continuous, flow micro-reactor at 500-550 C. Comparison of the <GaPO>> and <GaPON>> shows the importance of nitridation on the acido-basic properties of the catalyst. A deactivation of the catalyst, due to the deposition of carbonaceous species on the surface, was observed. As the properties of the oxynitride would be altered by a regeneration treatment at high temperature with flowing oxygen, the possibility of decreasing the deactivation rate by decreasing the reaction temperature and by adding hydrogen to the reactant mixture was explored. Catalytic tests, carried out at different hydrogen partial pressures, showed that the hydrogen inhibits the carbon deposition on the surface of the catalyst and thus increases the catalytic stability. (orig.)

Calculation on maximum accumulation of Pu-239 and Pu-241 from aqueous homogeneous reactor

International Nuclear Information System (INIS)

Ikhlas H Siregar; Frida Agung R; Suharyana; Azizul Khakim; Dahman Siregar

2016-01-01

Calculations on maximum accumulation of Pu-239 and Pu-241 using MCNPX computer code with UO_2(NO_3)_2 fuel solution enriched by 19.75% operating at temperature 80°C have been conducted. AHR design was simulated with cylindrical core having diameter of 63.4 cm and 122 cm high. From this geometry we found the reactor was critical with density 108 gr U/L of UO_2(NO_3)_2 solution. The result showed that multiplication factor (k_e_f_f) of AHR was 1.05284. Then the burn up calculations were done for various time intervals from 5 days until 285 years to analyze the result. From calculation, it was found out that the saturated concentration of Pu-239 was reached after 40-50 years of operation, producing 1.23 x 102 gr and the activity 7.645 Ci. While for operate time of AHR to produce Pu-241 should under 80 years with mass 21.7 gr and the activity 2.247 x 103 Ci. The accumulations of both isotopes are considered to be small, having low potential for misusing them for producing nuclear weapon. (author)

U, Pu, and Am nuclear signatures of the Thule hydrogen bomb debris

DEFF Research Database (Denmark)

Eriksson, Mats; Lindahl, Patric; Roos, Per

2008-01-01

). In the five hot particles examined, the measured uranium atomic ratio was U-235/U-238 = 1.02 +/- 0.16 and the Pu-isotopic ratios were as follows: Pu-240/Pu-239 0.0551 +/- 0.0008 (atom ratio), Pu-238/Pu239+240 = 0.0161 +/- 0.0005 (activity ratio), Pu-241/Pu239+240 = 0.87 +/- 0.12 (activity ratio), and Am-241...... than one Pu source involved in the accident, confirming earlier studies. The Pu-238/Pu239+240 activity ratio and the Pu-240/Pu-239 atomic ratio were divided into at least two Pu-isotopic ratio groups. For both Pu-isotopic ratios, one ratio group had identical ratios as the five hot particles described...... above and for the other groups the Pu isotopic ratios were lower (Pu-238/Pu239+240 activity ratio similar to 0.01 and the Pu-240/Pu-239 atomic ratio 0.03). On the studied particles we observed that the U/Pu ratio decreased as a function of the time these particles were present in the sediment. We...

Studies in the solubility of Pu(III) oxalate

Energy Technology Data Exchange (ETDEWEB)

Hasilkar, S P; Khedekar, N B; Chander, K; Jadhav, V; Jain, H C [Bhabha Atomic Research Centre, Bombay (India). Fuel Reprocessing Div.

1994-11-01

Studies have been carried out on the solubility of Pu(III) oxalate by precipitation of Pu(III) oxalate from varying concentrations of HNO[sub 3]/HCl (0.5-2.0M) solutions and also by equilibrating freshly prepared Pu(III) oxalate with solutions containing varying concentrations of HNO[sub 3]/HCl, oxalic acid and ascorbic acid. Pu(III) solutions in HNO[sub 3] and HCl media were prepared by reduction of Pu(IV) with ascorbic acid. 0.01-0.10M ascorbic acid concentration in the aqueous solution was maintained as holding reductant. The solubility of Pu(III) oxalate was found to be a minimum in 0.5M-1M HNO[sub 3]/HCl solutions containing 0.05M ascorbic acid and 0.2M excess oxalic acid in the supernatant. (author) 6 refs.; 6 tabs.

Assembly-level analysis of heterogeneous Th–Pu PWR fuel

International Nuclear Information System (INIS)

Zainuddin, Nurjuanis Zara; Parks, Geoffrey T.; Shwageraus, Eugene

2017-01-01

Highlights: • We directly compare homogeneous and heterogeneous Th–Pu fuel. • Examine whether there is an increase in Pu incineration in the latter. • Homogeneous fuel was able to achieve much higher Pu incineration. • In the heterogeneous case, U-233 breeding is faster (larger power fraction), thus decreasing incineration of Pu. - Abstract: This study compares homogeneous and heterogeneous thorium–plutonium (Th–Pu) fuel assemblies (with high Pu content – 20 wt%), and examines whether there is an increase in Pu incineration in the latter. A seed-blanket configuration based on the Radkowsky thorium reactor concept is used for the heterogeneous assembly. This separates the thorium blanket from the uranium seed, or in this case a plutonium seed. The seed supplies neutrons to the subcritical thorium blanket which encourages the in situ breeding and burning of "2"3"3U, allowing the fuel to stay critical for longer, extending burnup of the fuel. While past work on Th–Pu seed-blanket units shows superior Pu incineration compared to conventional U–Pu mixed oxide fuel, there is no literature to date that directly compares the performance of homogeneous and heterogeneous Th–Pu assembly configurations. Use of exactly the same fuel loading for both configurations allows the effects of spatial separation to be fully understood. It was found that the homogeneous fuel with and without burnable poisons was able to achieve much higher Pu incinerations than the heterogeneous fuel configurations, while still attaining a reasonably high discharge burnup. This is because in the heterogeneous cases, "2"3"3U breeding is faster, thereby contributing to a much larger fraction of total power produced by the assembly. In contrast, "2"3"3U build-up is slower in the homogeneous case and therefore Pu burning is greater. This "2"3"3U begins to contribute a significant fraction of power produced only towards the end of life, thus extending criticality, allowing more Pu to

A COMPARISON OF (PuU)C AND (PuU)O$sub 2$ FUELED FAST BREEDER REACTORS

Energy Technology Data Exchange (ETDEWEB)

Kazi, A. Halim; Rosen, Stanley

1963-11-15

BS>A conceptual evaluation is presented of a (PuU)C 500Mw(e) reactor which uses a moderate power generation of 40 kw/ft and a maximum fuel temperature of 2900 deg F, well below the 4500 deg F melting point of Pu/sub 0.2/U/sub 0.8/C. The principal design characteristics and fuel cycle costs are tabulated together with those of a (PuU)O/sub 2/ design of equal power. The comparison shows that the carbide core has significant economic and safety advantages over the oxide core. (D.L.C.)

Contribution to the study of the upper valence states of Pu

International Nuclear Information System (INIS)

Musante, Yves.

1975-01-01

The properties of the Pu(VI) and Pu(VII) ions in aqueous solutions were investigated: spectrophotometric study of the formation of PuO 2 2+ complexes with hydroxyl ions; electrochemical study of PuO 2 2+ ; preparation, determination and coprecipitation of Pu(VII); electrochemical study of Pu(VII). A preliminary research was made on the chemistry of Pu in non-aqueous solutions especially the dissolution and the determination of Pu in propylene carbonate [fr

Unsafe Coulomb excitation of 240-244Pu

International Nuclear Information System (INIS)

Ahmad, I.; Amro, H.; Carpenter, M. P.; Chowdhury, P.; Cizewski, J.; Cline, D.; Greene, J. P.; Hackman, G.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Macchiavelli, A. O.; Nisius, D. T.; Reiter, P.; Seabury, E. H.; Seweryniak, D.; Siem, S.; Uusitalo, J.; Wiedenhoever, I.; Wu, C. Y.

1999-01-01

The high spin states of 240 Pu and 244 Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a 208 Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to 242 Pu were obtained as well. In the case of 244 Pu, the yrast band was extended to 34h b ar revealing the completed πi 13/2 alignment, a ''first'' for actinide nuclei. The yrast sequence of 242 Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of 240 Pu was measured up to the highest rotational frequencies ever reported in the actinide region (approximately300 keV), no sign of particle alignment was observed. In this case, several observable such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or suppressing the πi 13/2 particle alignment

X-ray photoelectron spectroscopy study of Schottky barrier formation and thermal stability of the LaB6/GaAs(001) c (4 x 4) interface

International Nuclear Information System (INIS)

Yokotsuka, T.; Narusawa, T.; Uchida, Y.; Nakashima, H.

1987-01-01

Schottky barrier formation and thermal stability of the LaB 6 /GaAs(001) c (4 x 4) interface were investigated by x-ray photoelectron spectroscopy. Results show an excellent thermal stability without any appreciable interface reactions such as interdiffusion. Band bending induced by LaB 6 deposition is found to depend on the evaporation condition. However, the Fermi level pinning position does not change due to heat treatments between 300 and 700 0 C. This indicates that LaB 6 is a promising gate material for GaAs integrated circuits

Microbial Stabilization of Plutonium in the Subsurface Environment

International Nuclear Information System (INIS)

Honeyman, B.J.; Francis, A.J.; Dodge, C.J.; Gillow, J.B.; Santschi, P.H.

2004-01-01

This report outlines the results of work performed at the Colorado School of Mines, Brookhaven National Laboratory and Texas A and M University during the second reporting phase of this project. The sub-projects focused on this year include: (1) Biotransformation of Pu-contaminated soil; (2) Environmental colloids at the Rocky Flats Environmental Technology Site; (3) Production, isolation and characterization of EPS (exopolymeric substances, or exopolysaccharides); (4) Colloid trapping; (5) Determination of stability constants of complexes of Pu(IV) with organic ligands; and (6) The role of bacterial EPS in the transport of Pu through saturated porous media

Mucrobial Stabilization of Plutonium in the Subsurface Environment

Energy Technology Data Exchange (ETDEWEB)

Honeyman, B. D. [Colorado School of Mines, Golden, CO (United States). Environmental Science and Engineering Div., Lab. for Applied and Environmental Radiochemistry; Francis, A. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental Sciences Dept.; Dodge, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental Sciences Dept.; Gillow, J. B. [Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental Sciences Dept.; Sanschi, P. H. [Texas A & M Univ., Galveston, TX (United States). Dept. of Oceanography

2004-06-01

This report outlines the results of work performed at the Colorado School of Mines, Brookhaven National Laboratory and Texas A and M University during the second reporting phase of this project. The sub-projects focused on this year include: (1) Biotransformation of Pu-contaminated soil; (2) Environmental colloids at the Rocky Flats Environmental Technology Site; (3) Production, isolation and characterization of EPS (exopolymeric substances, or exopolysaccharides); (4) Colloid trapping; (5) Determination of stability constants of complexes of Pu(IV) with organic ligands; and (6) The role of bacterial EPS in the transport of Pu through saturated porous media.

Plutonium activities and 240Pu/ 239Pu atom ratios in sediment cores from the east China sea and Okinawa Trough: Sources and inventories

Science.gov (United States)

Wang, Zhong-liang; Yamada, Masatoshi

2005-05-01

Plutonium concentrations and 240Pu/ 239Pu atom ratios in the East China Sea and Okinawa Trough sediment cores were determined by isotope dilution inductively coupled plasma mass spectrometry after separation using ion-exchange chromatography. The results showed that 240Pu/ 239Pu atom ratios in the East China Sea and Okinawa Trough sediments, ranging from 0.21 to 0.33, were much higher than the reported value of global fallout (0.18). The highest 240Pu/ 239Pu ratios (0.32-0.33) were observed in the deepest Okinawa Trough sediment samples. These ratios suggested the US nuclear weapons tests in the early 1950s at the Pacific Proving Grounds in the Marshall Islands were a major source of plutonium in the East China Sea and Okinawa Trough sediments, in addition to the global fallout source. It was proposed that close-in fallout plutonium was delivered from the Pacific Proving Grounds test sites via early direct tropospheric fallout and transportation by the North Pacific Equatorial Circulation system and Kuroshio Current into the Okinawa Trough and East China Sea. The total 239 + 240 Pu inventories in the cores were about 150-200% of that expected from direct global fallout; about 46-67% of the total inventories were delivered from the Pacific Proving Grounds. Much higher 239 + 240 Pu inventories were observed in the East China Sea sediments than in sediments of the Okinawa Trough, because in the open oceans, part of the 239 + 240 Pu was still retained in the water column, and continued Pu scavenging was higher over the margin than the trough. According to the vertical distributions of 239 + 240 Pu activities and 240Pu/ 239Pu atom ratios in these cores, it was concluded that sediment mixing was the dominant process in controlling profiles of plutonium in this area. Faster mixing in the coastal samples has homogenized the entire 240Pu/ 239Pu ratio record today; slightly slower mixing and less scavenging in the Okinawa Trough have left the surface sediment ratios closer

Determination of plutonium isotopes (²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu) in environmental samples using radiochemical separation combined with radiometric and mass spectrometric measurements

DEFF Research Database (Denmark)

Xu, Yihong; Qiao, Jixin; Hou, Xiaolin

2014-01-01

counting and alpha spectrometry) and inductively coupled plasma mass spectrometry (ICP-MS) were applied for the measurement of plutonium isotopes. The decontamination factors for uranium were significantly improved up to 7.5×105 for 20 g soil compared to the level reported in the literature......, this is critical for the measurement of plutonium isotopes using mass spectrometric technique. Although the chemical yield of Pu in the entire procedure is about 55%, the analytical results of IAEA soil 6 and IAEA-367 in this work are in a good agreement with the values reported in the literature or reference......Pu. However, it is impossible to measure 238Pu using ICP-MS in environmental samples even a decontamination factor as high as 106 for uranium was obtained by chemical separation....

Estimation of Ni63, Pu241, Pu242 and Am243 from Co60, Pu239, and Cm244 activities in groundwater samples

International Nuclear Information System (INIS)

Holcomb, H.P.

1993-01-01

The Part B Permit for F ampersand H Seepage Basins calls for analysis of several constituents of concern in groundwater monitoring wells. Four of these analytes are the radionuclides Ni 63 , Pu 241 , Pu 242 , and Am 243 . These are currently not being analyzed due to their very difficult, tedious analytical schemes coupled with their relatively low activity values. This report demonstrates how the activity value for Ni 63 , a week beta emitter, can be estimated from that of Co 60 , an easily detectable, high-energy gamma emitter. Similarly, estimates of Pu 241 , a beta emitter, and the alpha-emitting Pu 242 can be made from the activity value of the more easily detected Pu 239 . Am 243 can be estimated from the activity of Cm 244 , which is easier to detect because of a shorter half-life (higher specific activity) and the emission of higher energy alpha particles. These correlations are made under very specific parameters in order to ensure the validity of this approach. Therefore, assumptions must be established setting ground rules for establishing these activity relationships. Bases for these assumptions are explained and/or referenced. Their degree of uncertainty limits the accuracy of the data so that the term ''estimate'' is used. Such soundly-based, conservative estimates for these four rads can provide a tool for evaluating any hazards from their presence over the next several years. Hopefully, during this time, sufficient advances will be made in their radiochemical analyses and in counting techniques so that in the future, their activities may be quantitatively determined more easily and also more cost effectively

Ceramic grade (U,Pu)O2 powder fabrication

International Nuclear Information System (INIS)

Cristallini, O.A.; Villegas de Maroto, Marina; De Pino, J.I.; Osuna, H.A.

1980-01-01

Ceramic grade UO 2 powder was obtained by the homogeneous precipitation method. This procedure was afterwards applied to the fabrication of ceramic grade (U,Pu)O 2 powders, and mixed oxide powders with Pu content ranging from 0.7 to 16% were obtained. The obtainment of mixed ceramic oxides as well as the recuperation of fabrication scraps were developed in three steps: 1)study of the process of homogeneous precipitation of ammonium diuranate (ADU); 2) co-precipitation of ADU/PuO 2 .H 2 O for Pu concentrations of 0.6 and 6.8; 3) the thermal conditioning to mixed oxide (U,Pu)O 2 powders. The experimental procedure involves the following steps: preparation of the PuO 2 (NO 3 ) 4 solution; co-precipitation of the PuO 2 (NO 3 ) 2 solution with an UO 2 (NO 3 ) 2 solution; filtration and drying of the precipitate, thermal treatment and finally, mixing, pressing and sintering of the (U,Pu)O 2 and Nukem UO 2 powder with a 0. of zinc stearate. Different controls were made by means of physical, chemical and ceramographic tests. This method can be used for the fabrication of fast reactor fuels or, previous mechanical dispersion in UO 2 powder, for the fabrication of thermal reactors fuels. (M.E.L.) [es

The State of Bay–Delta Science 2016: An Introduction

Directory of Open Access Journals (Sweden)

Michael Healey

2016-07-01

Full Text Available doi: http://dx.doi.org/10.15447/sfews.2016v14iss2art5The State of Bay–Delta Science 2016 (SBDS is a collection of papers that summarizes the scientific understanding of the Sacramento–San Joaquin Delta, emphasizing progress made during the past decade.It builds on the first SBDS edition (Healey et al. 2008. Paper topics for this edition address the most relevant scientific issues in the Delta identified by senior scientists and managers. The topical papers cover issues ranging from contaminants in the Delta to levee stability, and from Delta food webs to recent discoveries about salmon migration. These papers are written for a scientific audience. Two additional papers, one describing the challenges of managing water and ecosystems in the Delta and another that discusses policy implications of the recent scientific findings, are written for a general audience. The papers will be published in at least two issues of San Francisco Estuary and Watershed Science and will be available as a set electronically.

Np Analysis in IAT-Samples Containing <10 Microgram Pu

International Nuclear Information System (INIS)

Ludwig, R.; Raab, W.; Dashdondog, J.; Balsley, S.

2008-01-01

A method for the determination of neptunium to plutonium in safeguards samples containing less than 10 microgram Pu is presented. The chemical treatment and the optimized measurement conditions for gamma spectrometry are reported. This method is based on thermal ionization mass spectrometry (TIMS) after chemical treatment and separation and was validated with mixtures of U, Pu and Np certified reference materials and using the 237 Np standard addition method, followed by separation of the waste fraction and gamma spectrometric analysis. The highest sensitivity, precision and accuracy in the determination of the Np:Pu ratio at microgram levels of Pu is achieved by evaluating 241 Pu and 233 Pa after measuring the adsorbent with a well-type gamma detector 3 weeks after chemical treatment. The repeatability of determining the Np:Pu ratio is estimated to be 5%, the maximum uncertainty as determined from comparing the 4 measurement modes is within ± 10% for samples containing 3 μg Pu, while being within ± 20% for 0.4 μg Pu. (authors)

Np Analysis in IAT-Samples Containing <10 Microgram Pu

Energy Technology Data Exchange (ETDEWEB)

Ludwig, R.; Raab, W.; Dashdondog, J.; Balsley, S. [IAEA, Safeguards Analytical Laboratory, Wagramer Str. 5, P.O. Box 100, A-1400 Vienna (Austria)

2008-07-01

A method for the determination of neptunium to plutonium in safeguards samples containing less than 10 microgram Pu is presented. The chemical treatment and the optimized measurement conditions for gamma spectrometry are reported. This method is based on thermal ionization mass spectrometry (TIMS) after chemical treatment and separation and was validated with mixtures of U, Pu and Np certified reference materials and using the {sup 237}Np standard addition method, followed by separation of the waste fraction and gamma spectrometric analysis. The highest sensitivity, precision and accuracy in the determination of the Np:Pu ratio at microgram levels of Pu is achieved by evaluating {sup 241}Pu and {sup 233}Pa after measuring the adsorbent with a well-type gamma detector 3 weeks after chemical treatment. The repeatability of determining the Np:Pu ratio is estimated to be 5%, the maximum uncertainty as determined from comparing the 4 measurement modes is within {+-} 10% for samples containing 3 {mu}g Pu, while being within {+-} 20% for 0.4 {mu}g Pu. (authors)

Evaluation of fission cross sections and covariances for {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu

Energy Technology Data Exchange (ETDEWEB)

Kawano, Toshihiko [Kyushu Univ., Fukuoka (Japan); Matsunobu, Hiroyuki [Data Engineering, Inc. (Japan); Murata, Toru [AITEL Corporation, Tokyo (JP)] [and others

2000-02-01

A simultaneous evaluation code SOK (Simultaneous evaluation on KALMAN) has been developed, which is a least-squares fitting program to absolute and relative measurements. The SOK code was employed to evaluate the fission cross sections of {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu for the evaluated nuclear data library JENDL-3.3. Procedures of the simultaneous evaluation and the experimental database of the fission cross sections are described. The fission cross sections obtained were compared with evaluated values given in JENDL-3.2 and ENDF/B-VI. (author)

Quantitative dissolution of (U, Pu)O2 MOX (0.4% to 44% PuO2) using microwave heating technique

International Nuclear Information System (INIS)

Malav, R.K.; Fulzele, Ajit K.; Prakash, Amrit; Afzal, Md.; Panakkal, J.P.

2011-01-01

AFFF has fabricated the (U, Pu)O 2 mixed oxide fuels for PHWRs, BWRs, PFBRs and FBTRs. The quantitative dissolution of the fuel samples are required within time for accurate determination of uranium-plutonium in chemical quality control laboratory. This paper describes the use of microwave heating technique in quantitative dissolution of (U, Pu)O 2 MOX (from 0.4% to 44% PuO 2 ). (author)

Anisotropic expansion of Pu through the α-β-γ phase transitions while under radial compressive stress

Science.gov (United States)

Spearing, Dane R.; Veirs, D. Kirk; Prenger, F. Coyne

2000-07-01

In support of the new US Department of Energy (DOE) standard for the stabilization, packaging, and storage of plutonium bearing materials, the effects of the volume expansion associated with the α/β and β/γ transformations of Pu metal on the integrity of a stainless steel storage container were examined.

Analysis and composition of the first U-Pu charge (0,043 per cent of Pu); Analyse et constitution du 1. jeu U-Pu (0,043 pour cent de Pu)

Energy Technology Data Exchange (ETDEWEB)

Brunet, J P; Lapparent, D de; Lourme, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

Checking the homogeneity in the content of plutonium of 0,043 per cent Pu-natural uranium alloy slugs has been made by Pu 240 and U 238 spontaneous fissions neutrons counting. The purpose of the test was to select groups of slugs to be correctly associated into fuel rods for critical experiments. General technic for spontaneous fissions counting, then elaboration of data in view of ranking the slugs are described. Results are given for this particular case. (authors) [French] On a effectue un controle d'homogeneite de teneur en plutonium sur des billettes d'alliage 0,043 pour cent Pu-uranium naturel, par comptage des fissions spontanees du plutonium 240 et de l'uranium 238. Le but du controle etait de permettre une association correcte de ces billettes a l'interieur des elements combustibles destines a servir dans des experiences critiques. On indique la methode generale de comptage des fissions spontanees, puis le depouillement des donnees en vue du classement des barreaux. Les resultats pour ce cas particulier sont donnes dans le rapport. (auteurs)

242Pu: Preliminary evaluation with consideration of 240Pu, and some sensitivity results

International Nuclear Information System (INIS)

Jary, J.; Lagrange, C.; Philis, C.

1978-01-01

A preliminary evaluation of 242 Pu nuclear data is presented for the neutron energy range from 10 keV to 20 MeV. The fission cross section is based upon recent experimental measurements on 242 Pu. The remaining cross sections have been calculated using various nuclear models with parameters obtained mainly by both fits on 240 Pu experimental data and general reflexions on the actinides. Particular care has been taken of the direct interactions. The laws of secondary neutron energy spectra and the average number of neutrons produced per fission have been evaluated. The results have been placed in ENDF/BIV format and combined with the low energy region of ENDF/BIV MAT = 1161 data to make complete the evaluation over the whole energy range 10 -5 eV - 20 MeV. Finally, the sensitivities of some of these nuclear data available for reactor calculations are given in terms of the variation of the calculated critical masses

Morphodynamic evolution of two deltas in arctic environments, east coast of Greenland

DEFF Research Database (Denmark)

Kroon, Aart; Pedersen, Jørn Bjarke Torp; Sigsgaard, Charlotte

2011-01-01

Changes in fluvial channel patterns on deltas have a significant impact on the coastal morphology along its fringes. Lateral channel migration can locally cause cliff erosion and introduce an extra sediment source in the local budget of an active delta plain. Stabilization of channels or even...... channel lobe switching reduce the fluvial impact on the delta and introduce the formation of beach ridges and spits along the (former) delta edge. These accumulative features are formed in the ice-free summer periods and fed by alongshore sediment input from adjacent shores due to wave-driven alongshore...... currents, and by the reworking of the sediments on the delta plain by wave-driven cross-shore processes....

Measurement of oxygen chemical diffusion in PuO{sub 2-x} and analysis of oxygen diffusion in PuO{sub 2-x} and (Pu,U)O{sub 2-x}

Energy Technology Data Exchange (ETDEWEB)

Kato, Masato; Uchida, Teppei [Advanced Nuclear System Research and Development Directorate, Japan Atomic Energy Agency, 4-33 Muramatsu, Tokai-mura, Ibaraki 319-1194 (Japan); Sunaoshi, Takeo [Inspection Development Company Ltd., 4-33 Muramatsu, Tokai-mura, Ibaraki 319-1194 (Japan)

2013-02-15

Oxygen chemical diffusion in PuO{sub 2-x} was investigated in the temperature range of 1473-1873 K by thermogravimetry as functions of oxygen-to-metal (O/M) ratios and temperatures. The oxygen chemical diffusion coefficients, D were determined assuming that the reduction curves were dominated by a diffusion process. The O/M ratio and Pu content dependence on the chemical diffusion coefficients were evaluated. The chemical diffusion coefficient had its minimum value at around O/M=1.98 and decreased with increasing Pu content in (U,Pu)O{sub 2-x}. The self-diffusion coefficients were evaluated. A model for describing the relationship among O/M ratio, oxygen chemical diffusion, and self-diffusion was proposed based on defect chemistry. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The Transport of Close-In Fallout Plutonium in the Northwest Pacific Ocean: Tracing the Water Mass Movement Using {sup 240}Pu/{sup 239}Pu Atom Ratio

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang-Han [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Hong, Gi-Hoon; Suk, Moon-Sik [Korea Ocean Research and Development Institute, Seoul (Korea, Republic of); Gastaud, J. [International Atomic Energy Agency, Marine Environment Laboratory (Monaco); La Rosa, J. [National Institute of Standards and Technology, Ionizing Radiation Division, Gaithersburg, Maryland (United States); Kim, Chul-Soo [Environmental Laboratories, International Atomic Energy Agency, Seibersdorf (Austria); Wyse, E. [New Brunswick Laboratory Argonne, IL (United States); Povinec, P. P. [Comenius University, Faculty of Mathematics and Physics, Bratislava (Slovakia)

2013-07-15

{sup 240}Pu/{sup 239}Pu atom ratios in seawater and surface sediment collected from the northwest (NW) Pacific Ocean from 1992 to 1997 were determined using ICP-sector field mass spectrometry (ICP-MS). In whole water columns, the atom ratios of {sup 240}Pu/{sup 239}Pu were higher than the global fallout ratio (0.18). It is noted that the atom ratios of {sup 240}Pu/2{sup 39}Pu in the seawater increase with depth. Such elevated {sup 240}Pu/{sup 239}Pu atom ratios indicate that the close-in fallout plutonium isotopes originating from the Pacific Proving Grounds (PPGs) due to the U.S. tests are prevailing in the seawater in the NW Pacific Ocean. However, the {sup 240}Pu/{sup 239}Pu atom ratios in the surface sediment from the NW Pacific Ocean varied with the sampling locations. As a consequence, this study will provide the information that the water mass along with the current plays a key role in driving the distribution of Pu and in transporting Pu from the PPGs to the far eastern marginal sea in the NW Pacific Ocean. (author)

Thermodynamic evaluation of liquid Cd cathode containing U and Pu

International Nuclear Information System (INIS)

Kurata, Masaki; Uozumi, Koichi; Kato, Tetsuya; Iizuka, Masatoshi

2009-01-01

In our previous study, a mixture of U and Pu was recovered in liquid Cd cathode from molten salt under various conditions of the U:Pu ratio. Two important things were observed. The first was that three kinds of precipitated phase had been detected in the saturated liquid Cd cathode, such as a U metal and two kinds of U-Pu-Cd compound. The compositions of the compounds were roughly (U+Pu):Cd=1:11 and (U+Pu):Cd=1:6. The second was that the U metal had selectively precipitated in the saturated liquid Cd cathode under the condition that the U:Pu ratio is higher than about 0.8 in the liquid Cd phase. In the present study, phase diagrams were evaluated by the CALPHAD method on the liquid Cd cathode containing U and Pu. The U-Pu-Cd compounds were modeled as MCd 11 -type and MCd 6 -type, respectively, based on the reported binary phase diagrams of U-Cd and Pu-Cd. The calculated result reasonably agreed with the experimental observations. The variations in the U and Pu activities were estimated along with the U:Pu ratio, which is related to the precipitation of various phases in the liquid Cd cathode. (author)

Roles of PU.1 in monocyte- and mast cell-specific gene regulation: PU.1 transactivates CIITA pIV in cooperation with IFN-gamma.

Science.gov (United States)

Ito, Tomonobu; Nishiyama, Chiharu; Nakano, Nobuhiro; Nishiyama, Makoto; Usui, Yoshihiko; Takeda, Kazuyoshi; Kanada, Shunsuke; Fukuyama, Kanako; Akiba, Hisaya; Tokura, Tomoko; Hara, Mutsuko; Tsuboi, Ryoji; Ogawa, Hideoki; Okumura, Ko

2009-07-01

Over-expression of PU.1, a myeloid- and lymphoid-specific transcription factor belonging to the Ets family, induces monocyte-specific gene expression in mast cells. However, the effects of PU.1 on each target gene and the involvement of cytokine signaling in PU.1-mediated gene expression are largely unknown. In the present study, PU.1 was over-expressed in two different types of bone marrow-derived cultured mast cells (BMMCs): BMMCs cultured with IL-3 plus stem cell factor (SCF) and BMMCs cultured with pokeweed mitogen-stimulated spleen-conditioned medium (PWM-SCM). PU.1 over-expression induced expression of MHC class II, CD11b, CD11c and F4/80 on PWM-SCM-cultured BMMCs, whereas IL-3/SCF-cultured BMMCs expressed CD11b and F4/80, but not MHC class II or CD11c. When IFN-gamma was added to the IL-3/SCF-based medium, PU.1 transfectant acquired MHC class II expression, which was abolished by antibody neutralization or in Ifngr(-/-) BMMCs, through the induction of expression of the MHC class II transactivator, CIITA. Real-time PCR detected CIITA mRNA driven by the fourth promoter, pIV, and chromatin immunoprecipitation indicated direct binding of PU.1 to pIV in PU.1-over-expressing BMMCs. PU.1-over-expressing cells showed a marked increase in IL-6 production in response to LPS stimulation in both IL-3/SCF and PWM-SCM cultures. These results suggest that PU.1 overproduction alone is sufficient for both expression of CD11b and F4/80 and for amplification of LPS-induced IL-6 production. However, IFN-gamma stimulation is essential for PU.1-mediated transactivation of CIITA pIV. Reduced expression of mast cell-related molecules and transcription factors GATA-1/2 and up-regulation of C/EBPalpha in PU.1 transfectants indicate that enforced PU.1 suppresses mast cell-specific gene expression through these transcription factors.

Investigation of carrier dynamics in InAs/GaAsSb quantum dots with different silicon delta-doping levels

Energy Technology Data Exchange (ETDEWEB)

Ban, Keun-Yong [Arizona State Univ., Tempe, AZ (United States). School of Electrical, Computer and Energy Engineering; Kim, Yeongho [Korea Research Inst. of Chemistry Technology (KRICT), Daejeon (Korea, Republic of). Division of Metrology for Future Technology; Kuciauskas, Darius [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bremner, Stephen P. [Univ. of New South Wales, Sydney, NSW (Australia). School of Photovoltaic and Renewable Energy Engineering; Honsberg, Christiana B. [Arizona State Univ., Tempe, AZ (United States). School of Electrical, Computer and Energy Engineering

2016-11-10

The optical properties of InAs quantum dots (QDs) embedded in a GaAsSb matrix with different delta (d)-doping levels of 0, 2, 4, and 6 electrons per dot (e-/dot), incorporated to control the occupation of QD electronic states, are studied by photoluminescence (PL) spectroscopy. The time-resolved PL data taken at 10 K reveal that the increase of δ-doping density from 2 to 6 e^-/dot decreases the recombination lifetime of carriers at ground states of the QDs from 996 ± 36 to 792 ± 19 ps, respectively. Furthermore, the carrier lifetime of the sample with 4 e^-/dot is found to increase at a slower rate than that of the undoped sample as temperature increases above 70 K. An Arrhenius plot of the temperature dependent PL intensity indicates that the thermal activation energy of electrons in the QDs, required for carrier escape from the dot ground state to continuum state, is increased when the d-doping density is high enough (>4 e^-/dot). These results are attributed to the enhanced Coulomb interaction of electrons provided by the d-doping, leading to reduced thermal quenching of the PL.

Structural studies of the phase separation in the UO2–PuO2–Pu2O3 ternary system

International Nuclear Information System (INIS)

Truphémus, Thibaut; Belin, Renaud C.; Richaud, Jean-Christophe; Reynaud, Muriel; Martinez, Marie-Annick; Félines, Isabelle; Arredondo, Antoine; Miard, Audrey; Dubois, Thierry; Adenot, Frédéric; Rogez, Jacques

2013-01-01

In the oxygen hypo-stoichiometric range of (U 1−y Pu y )O 2−x mixed oxide MOX fuels, the U–Pu–O phase diagram is known to exhibit a large biphasic domain depending on the Pu content. However, the phase equilibria are still to be fully described as various representations are proposed in the literature. In the present work, we notify new insights into the phase separation occurring in the UO 2 –PuO 2 –Pu 2 O 3 domain at room temperature. Our microstructural and X-ray diffraction results are compared to the different representations reported in the literature. We provide, for the first time in the hypo-stoichiometric domain, an indisputable experimental observation of a triphasic region at high Pu content, composed of two fluorite-type structures and of one α-Pu 2 O 3 sesquioxyde type structure. These results are in contradiction with previous experimental representations of the U–Pu–O ternary system.

Assessment of 238Pu and 239+240Pu, in marine sediments of the oceans Atlantic and Pacific of Guatemala

International Nuclear Information System (INIS)

Mendez Ochaita, L.

2000-01-01

In this investigation samples of marine sediments were taken from 14 places representatives of the oceans coast of Guatemala. For the assesment of 238 Pu and 239+240 Pu in sediments a radiochemical method was used to mineralize sediments and by ionic interchange it was separated from other elements, after that an electrodeposition of plutonium was made in metallic discs. The radioactivity of plutonium was measured by alpha spectrometry system and the alpha spectrums were obtained. The levels of plutonium are not higher than other countries that shown contamination. The contamination of isotope of 239+240 Pu is higher than 238 Pu and the contamination by two isotopes of plutonium is higher in the Atlantic than the Pacific ocean

Study of new U(VI) and Pu(VI) coprecipitation methods for the preparation of (U,Pu)O2

International Nuclear Information System (INIS)

Sanoit, J. de.

1990-01-01

Two U(VI) and Pu(VI) coprecipitation methods have been studied, for the definition of new processes to prepare (U,Pu)O 2 mixed oxides suitable for making MoX fuels or fast breeder reactor fuels. The first system is based on the coprecipitation of a new U(VI), Pu(VI) compound; ammonium uranoplutonate, where as a second system is related to the precipitation of uranyl plutonyl monocarbonate. Experimental conditions to optimize the precipitation and the filtration steps of these two systems have been determined. After calcination under reducing conditions, the mixed oxides obtained are characterized according to different techniques: granulometry, thermogravimetry, solubility in boiling HNO 3 solutions. The properties of such oxides are excellent. The possible processes for preparing (U, Pu)O 2 using these new routes are compared with those actually exploited [fr

Chemical speciation of Pu in natural waters

International Nuclear Information System (INIS)

Nelson, D.M.; Larsen, R.P.; Penrose, W.R.

1983-01-01

The behavior of plutonium in natural waters is determined to a major degree by the chemical forms which are present. We have characterized the ambient Pu in a number of surface waters with regard to its oxidation state and association with natural colloidal organic carbon compounds using a combination of field measurements and laboratory experiments. Both of these factors are shown to have a profound effect on the adsorption of Pu to natural sediments, since both complexation with organic matter and oxidation compete with adsorption. The concentration of organic carbon in the water is the key variable influencing both oxidation state and organic binding. The adsorption process conforms to the laws applicable to a reversible equilibrium with values of the distribution coefficient, K/sub D/, measured in laboratory experiments being similar to those observed for ambient Pu. Experiments using natural waters and sediments in which the Pu concentration was varied show the forms present at typical ambient concentrations (10 -17 - 10 -14 M) are the same as those found at concentrations up to 10 -7 M. Moreover, the affinity for sediments did not change with concentration indicating the binding sites for Pu had not become saturated. Thus, the behavior observed for Pu at ultratrace concentrations should remain unchanged throughout this concentration range. The studies in this report all deal with Pu in exchangeable (and hence source independent) forms and should therefore reflect the behavior toward which the plutonium from any source will tend with time. 13 references, 7 figures, 10 tables

Nitrate Anion Exchange in Pu-238 Aqueous Scrap Recovery Operations

International Nuclear Information System (INIS)

Pansoy-Hjelvik, M.E.; Silver, G.L.; Reimus, M.A.H.; Ramsey, K.B.

1999-01-01

Strong base, nitrate anion exchange (IX) is crucial to the purification of 238 Pu solution feedstocks with gross levels of impurities. This paper discusses the work involved in bench scale experiments to optimize the nitrate anion exchange process. In particular, results are presented of experiments conducted to (a) demonstrate that high levels of impurities can be separated from 238 Pu solutions via nitrate anion exchange and, (b) work out chemical pretreatment methodology to adjust and maintain 238 Pu in the IV oxidation state to optimize the Pu(IV)-hexanitrato anionic complex sorption to Reillex-HPQ resin. Additional experiments performed to determine the best chemical treatment methodology to enhance recovery of sorbed Pu from the resin, and VIS-NIR absorption studies to determine the steady state equilibrium of Pu(IV), Pu(III), and Pu(VI) in nitric acid are discussed

Electronic structure of α- and δ-Pu from photoelectron spectroscopy

International Nuclear Information System (INIS)

Arko, A. J.; Joyce, J. J.; Morales, L.; Wills, J.; Lashley, J.; Wastin, F.; Rebizant, J.

2000-01-01

We report photoemission results on α- and δ-Pu using a laser plasma light source (LPLS) as well as He light as the exciting radiation. The LPLS is a pseudocontinuum tunable light source with intensities rivaling some second-generation synchrotrons. Both phases of Pu display a narrow, temperature-independent, 5f-related feature at the Fermi energy, which is narrower in δ-Pu than in α-Pu, suggestive of possible heavy-fermion-like behavior. In both α-Pu and δ-Pu the photon-energy dependence of this feature suggests some 6d admixture, albeit somewhat smaller in δ-Pu. In this respect it differs qualitatively from Ce and U heavy fermions. (c) 2000 The American Physical Society

Aspects of 238Pu production in the experimental fast reactor JOYO

International Nuclear Information System (INIS)

Osaka, Masahiko; Koyama, Shin-ichi; Tanaka, Kenya; Itoh, Masahiko; Saito, Masaki

2005-01-01

Experimental determination of 238 Pu in 237 Np samples irradiated in the experimental fast reactor JOYO was done as part of the demonstration of 238 Pu production from 237 Np in fast reactors within the framework of the protected Pu production project, which aims at reinforcement of proliferation resistance of Pu by increasing the 238 Pu isotopic ratio. 238 Pu production amount in the irradiated 237 Np samples was determined by a radioanalytical technique. Aspects of 238 Pu production were examined on the basis of the present radioanalysis. The 238 Pu production amount depends on the neutron spectrum which can range from that of a typical fast reactor to a nearly epi-thermal spectrum. It is concluded that the fast reactor has not only high potential for use in protected Pu production, but also as an incinerator for excess Pu

137Cs, 239+24Pu and 24Pu/239Pu atom ratios in the surface waters of the western North Pacific Ocean, eastern Indian Ocean and their adjacent seas

International Nuclear Information System (INIS)

Yamada, Masatoshi; Zheng Jian; Wang Zhongliang

2006-01-01

Surface seawater samples were collected along the track of the R/V Hakuho-Maru cruise (KH-96-5) from Tokyo to the Southern Ocean. The 137 Cs activities were determined for the surface waters in the western North Pacific Ocean, the Sulu and Indonesian Seas, the eastern Indian Ocean, the Bay of Bengal, the Andaman Sea, and the South China Sea. The 137 Cs activities showed a wide variation with values ranging from 1.1 Bq m -3 in the Antarctic Circumpolar Region of the Southern Ocean to 3 Bq m -3 in the western North Pacific Ocean and the South China Sea. The latitudinal distributions of 137 Cs activity were not reflective of that of the integrated deposition density of atmospheric global fallout. The removal rates of 137 Cs from the surface waters were roughly estimated from the two data sets of Miyake et al. [Miyake Y, Saruhashi K, Sugimura Y, Kanazawa T, Hirose K. Contents of 137 Cs, plutonium and americium isotopes in the Southern Ocean waters. Pap Meteorol Geophys 1988;39:95-113] and this study to be 0.016 yr -1 in the Sulu and Indonesian Seas, 0.033 yr -1 in the Bay of Bengal and Andaman Sea, and 0.029 yr -1 in the South China Sea. These values were much lower than that in the coastal surface water of the western Northwest Pacific Ocean. This was likely due to less horizontal and vertical mixing of water masses and less scavenging. 239+24 Pu activities and 24 Pu/ 239 Pu atom ratios were also determined for the surface waters in the western North Pacific Ocean, the Sulu and Indonesian Seas and the South China Sea. The 24 Pu / 239 Pu atom ratios ranged from 0.199 ± 0.026 to 0.248 ± 0.027 on average, and were significantly higher than the global stratospheric fallout ratio of 0.18. The contributions of the North Pacific Proving Grounds close-in fallout Pu were estimated to be 20% for the western North Pacific Ocean, 39% for the Sulu and Indonesian Seas and 42% for the South China Sea by using the two end-member mixing model. The higher 24 Pu / 239 Pu atom ratios

Experimental Benchmarking of Pu Electronic Structure

International Nuclear Information System (INIS)

Tobin, J.G.; Moore, K.T.; Chung, B.W.; Wall, M.A.; Schwartz, A.J.; Ebbinghaus, B.B.; Butterfield, M.T.; Teslich, N.E. Jr.; Bliss, R.A.; Morton, S.A.; Yu, S.W.; Komesu, T.; Waddill, G.D.; van der Laan, G.; Kutepov, A.L.

2008-01-01

The standard method to determine the band structure of a condensed phase material is to (1) obtain a single crystal with a well defined surface and (2) map the bands with angle resolved photoelectron spectroscopy (occupied or valence bands) and inverse photoelectron spectroscopy (unoccupied or conduction bands). Unfortunately, in the case of Pu, the single crystals of Pu are either nonexistent, very small and/or having poorly defined surfaces. Furthermore, effects such as electron correlation and a large spin-orbit splitting in the 5f states have further complicated the situation. Thus, we have embarked upon the utilization of unorthodox electron spectroscopies, to circumvent the problems caused by the absence of large single crystals of Pu with well-defined surfaces. Our approach includes the techniques of resonant photoelectron spectroscopy, x-ray absorption spectroscopy, electron energy loss spectroscopy, Fano Effect measurements, and Bremstrahlung Isochromat Spectroscopy, including the utilization of micro-focused beams to probe single-crystallite regions of polycrystalline Pu samples.

Transuranic concentrations in reef and pelagic fish from the Marshall Islands. [/sup 239/Pu, /sup 240/Pu

Energy Technology Data Exchange (ETDEWEB)

Noshkin, V.E.; Eagle, R.J.; Wong, K.M.; Jokela, T.A.

1980-09-01

Concentrations of /sup 239 + 240/Pu are reported in tissues of several species of reef and pelagic fish caught at 14 different atolls in the northern Marshall Islands. Several regularities that are species dependent are evident in the distribution of /sup 239 + 240/Pu among different body tissues. Concentrations in liver always exceeded those in bone and concentrations were lowest in the muscle of all fish analyzed. A progressive discrimination against /sup 239 + 240/Pu was observed at successive trophic levels at all atolls except Bikini and Enewetak, where it was difficult to conclude if any real difference exists between the average concentration factor for /sup 239 + 240/Pu among all fish, which include bottom feeding and grazing herbivores, bottom feeding carnivores, and pelagic carnivores from different atoll locations. The average concentration of /sup 239 + 240/Pu in the muscle of surgeonfish from Bikini and Enewetak was not significantly different from the average concentrations determined in these fish at the other, lesser contaminated atolls. Concentrations among all 3rd, 4th, and 5th trophic level species are highest at Bikini where higher environmental concentrations are found. The reasons for the anomalously low concentrations in herbivores from Bikini and Enewetak are not known.

ZZ WPPR-FR-MOX/BNCMK, Benchmark on Pu Burner Fast Reactor

International Nuclear Information System (INIS)

Garnier, J.C.; Ikegami, T.

1993-01-01

Description of program or function: In order to intercompare the characteristics of the different reactors considered for Pu recycling, in terms of neutron economy, minor actinide production, uranium content versus Pu burning, the NSC Working Party on Physics of Plutonium Recycling (WPPR) is setting up several benchmark studies. They cover in particular the case of the evolution of the Pu quality and Pu fissile content for Pu recycling in PWRs; the void coefficient in PWRs partly fuelled with MOX versus Pu content; the physics characteristics of non-standard fast reactors with breeding ratios around 0.5. The following benchmarks are considered here: - Fast reactors: Pu Burner MOX fuel, Pu Burner metal fuel; - PWRs: MOX recycling (bad quality Pu), Multiple MOX recycling

Biosphere in 3.5 Ga submarine hydrothermal system

Energy Technology Data Exchange (ETDEWEB)

Ueno, Yuichiro [Tokyo Univ. (Japan). Dept. of Earth Science and Astronomy

2003-04-01

Abundant organic matter (kerogen) was identified in {approx}3.5 Ga hydrothermal silica dikes from the North Pole area in the Pilbara craton, Western Australia. The silica dikes developed in the uppermost 1000 m of the ancient oceanic crust. Thus, they would have been deposited in the 3.5 Ga sub-seafloor hydrothermal system. The carbon and nitrogen isotopic compositions of the kerogen were analyzed in this study. Their highly {sup 13}C-depleted isotopic compositions ({delta}{sup 13}C = -38 to -33 per mille) strongly suggest that they are originally derived from biologically produced organic matter. The remarkable similarity of the {delta}{sup 13}C values between the kerogen and modern hydrothermal vent organisms may suggest that the kerogen was derived from chemoautotrophic organisms. This idea is also consistent with their nitrogen isotopic compositions ({delta}{sup 15}N = -4 to +4 per mille). The silica dikes consist mainly of fine-grained silica with minor pyrite and sphalerite. These mineral assemblages indicate that the silica dike was deposited from relatively low-temperature (probably less than 150degC) reducing hydrothermal fluid. Thus, anaerobic thermophilic/hyperthermophilic organisms could have survived in the hydrothermal fluid, which formed the silica dikes. Therefore, it is plausible that a chemoautotrophic-based biosphere (possibly methanogenesis) probably existed in the Early Archean sub-seafloor hydrothermal system. (author)

Mathematical modeling of radiation-chemical processes in HNO3 solutions of Pu. 5. Effect of [HNO3] on rate constants of radiation-chemical and chemical reactions of Pu ions

International Nuclear Information System (INIS)

Vladimirova, M.V.

1993-01-01

Dependences of rate constants on [HNO 3 ] are obtained for the reactions Pu(IV) + OH, Pu(IV) + NO 3 , Pu(V) + NO 2 , Pu(III) + NO 2 , Pu(V) + Pu(III), Pu(IV) + Pu(IV), and Pu(V) + Pu(V). These dependences are obtained for [HNO 3 ] = 0.3-6 M using existing experimental and literature data and the data obtained using mathematical modeling. The correctness of the resulting dependences is checked by comparing the calculated and experimental kinetic laws for the behavior of Pu in 0.3, 0.4, 0.6, and 1.6 M HNO 3 . 17 refs., 15 figs., 2 tabs

Sorption of Pu onto some kinds of clay

International Nuclear Information System (INIS)

Jia Haihong; Si Gaohua; Liu Wei; Yu Jing

2010-01-01

There are rich clay mines holding in one area, so it's necessary to know about these clays' sorption capacity to Pu, for building radioactive waste repository in the area. Distribution coefficients of Pu onto different clays were acquired in static method, with the result about 104. The size of clay is different, but the result of Kds is near. In addition, it's estimated how far Pu moves in the most rapid speed in the clay based on these Kids', disregarding the influence of Pu-colloid. In a word, as a kind of backfilling material clays in the area can effectively prevent Pu from moving to environment, and when designing the backfilling layer, it's not necessary to catch clays through NO.200 sieve, if only considering the influence of Kd. (authors)

239Pu standards for quantitative neutron-induced autoradiography

International Nuclear Information System (INIS)

Smith, J.M.; Atherton, D.R.; Wronski, T.J.; Jee, W.S.S.

1977-01-01

The present study deals with the preparation of 239 Pu standards for neutron bone tissue autoradiography and the calibration of these standards with respect to uranium reference standards. Known concentrations of 239 Pu were prepared in methyl methacrylate and Bioplastic casting resin bars. Wafers sawed from these bars served as standards. Solid state nuclear tract detectors (Lexan polycarbonate) were used to record fission fragment tracks after the standards were exposed to a thermal neutron flux. The original bars were found to contain a uniform distribution of 239 Pu. To confirm the concentration of 239 Pu in the wafers, the induced track density from the 239 Pu standards was compared with that from uranium reference standards. The average fission fragment detection efficiency for all of the standards was 0.51

Adsorption of Pu(IV) Polymer onto 304L Stainless Steel

International Nuclear Information System (INIS)

Bronikowski, M.G.

1999-01-01

'The report, Technical Basis for Safe Operations with Pu-239 Polymer in NMS and S Operating Facilities (F and H Areas), (WSRC-TR-99-00008) was issued in an effort to upgrade the Authorization Basis (AB) for H Area facilities relative to nuclear criticality. At the time, insufficient data were found in the literature to quantify the adsorption of Pu polymer onto the surfaces of stainless steel tanks. Additional experimental or literature information on the adsorption of Pu(IV) polymer and its removal was deemed necessary to support the H Area AB. The results obtained are also applicable to processing in F Area facilities.Additional literature sources suggest that adsorption on the tank walls should not be a safety concern. The sources show that the amount of Pu polymer that adsorbs from a solution comes to a limiting amount in 5 to 7 days after which no additional Pu is adsorbed. Adsorption increases with Pu concentration and decreases with acid concentration. The adsorbed amounts are small varying from 0.5 mg/cm2 for a 0.5 g/l Pu / 0.5M HNO3 solution to 11 mg/cm2 for a 1-3 g/l Pu / 0.1M HNO3 solution. Additionally, acid concentrations greater than 0.1M will remove a percentage of adsorbed Pu.The experimental results have generally confirmed much of what has been reported in the literature. Specifically, adsorption onto stainless steel was found to increase with increased Pu concentration, and decreased acid concentration. The amount adsorbed was found to come to a limiting amount after 5 to 7 days. Pu adsorbed as polymer was found to be harder to remove than if it was adsorbed as Pu(IV). The amount of Pu adsorbed as polymer was found to be almost an order of magnitude more than that from a similar concentration Pu(IV) solution. Unlike the literature, only a slight increase in adsorption values was found when the steel surface was removed, dried, and replaced in the Pu solution. The amount of Pu as polymer which would adsorb onto the surface of a 14,000L tank was

Simulation of 239Pu location in trabecular bone: a computerized model of adult endosteal bone remodeling and its interaction with injected 239Pu

International Nuclear Information System (INIS)

Kimmel, D.B.; Jee, W.S.S.

1979-01-01

A computer simulation of the relationship of bone microanatomic metabolic activity to the microscopic location of 239 Pu in bone has been attempted. The model incorporates the rate of bone turnover, cell location and density, bone resorptive activity (as it removes 239 Pu from bone), bone formation activity (as it buries 239 Pu in bone), recycling of 239 Pu, and liver translocation of 239 Pu to bone, such that the skeletal retention curve for 239 Pu injected in monomeric form into the young adult beagle is matched. The eventual aim of this work is to calculate the radiation dose to bone cells, knowing the relative location of 239 Pu deposited in bone and the cells that reside at bone surfaces as it changes throughout the lifespan of an animal. Early results indicate that osteosarcoma incidence may be proportional to the number of alpha hits which occur to osteoprogenitor cells and osteoblasts, the dividing cell population found near surfaces where bone turnover is in progress

DELTAS: A new Global Delta Sustainability Initiative (Invited)

Science.gov (United States)

Foufoula-Georgiou, E.

2013-12-01

Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

Characteristics of carbonaceous aerosol in PM 2.5: Pearl Delta River Region, China

Science.gov (United States)

Huang, H.; Ho, K. F.; Lee, S. C.; Tsang, P. K.; Ho, Steven Sai Hang; Zou, C. W.; Zou, S. C.; Cao, J. J.; Xu, H. M.

2012-02-01

Simultaneous measurements of atmospheric organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) were made at four sampling sites, namely Guangzhou (GZ), Zhaoqing (ZQ), PolyU Campus (PU) and Hok Tsui (HT), in the Pearl River Delta (PRD) region between 14 August 2006 and 28 August 2007. The highest concentrations of total carbon (TC) were found at the medium-scale roadside site (PU) and the lowest were found at the regional-scale site (HT). Among the four sampling sites, the average WSOC at ZQ showed the highest concentrations, while the lowest were seen at HT. OC and EC concentrations revealed spring/summer minima and autumn/winter maxima at all sites except PU, which had a consistently high EC concentration all over the year. The highest WSOC/OC ratio was found at ZQ with an average of 0.41, suggesting that the OC was more oxidized in the atmosphere of the semi-rural site. The lowest WSOC/OC was found at the roadside site of PU. Moreover, the WSOC/OC ratio increased in autumn, when the photochemical reactions are the most active in the PRD region. This can be attributed to aging and atmospheric processing of the organic compounds during their transportation, or to the formation of secondary organic aerosol (SOA). Average annual secondary organic carbon (SOC) concentrations in PM2.5 were estimated to be 2.2 and 3.5 μg m- 3 for GZ and ZQ, comprising 33.5% and 42.8% of the corresponding OC concentrations, respectively. The results indicate that SOC is significant in the PRD region, and its formation mostly occurs within the region.

1.5 μm InAs/InGaAsP/InP quantum dot laser with improved temperature stability

DEFF Research Database (Denmark)

Zubov, F. I.; Gladii, S. P.; Shernyakov, Yu M.

2016-01-01

Temperature characteristics of InAs/InGaAsP quantum dot (QD) lasers synthesized on InP (001) substrate are presented. The lasers demonstrate high temperature stability: a threshold current characteristic temperature as high as 205 K in the temperature range between 20 to 50°C was measured. Lasing...

Transfer of 239Pu to mouse fetoplacental tissues

International Nuclear Information System (INIS)

Kubota, Yoshihisa; Sato, Hiroshi; Koshimoto, Chihiro; Takahashi, Sentaro

1993-01-01

Cross-placental transfer of 239 Pu from the mother to fetus was studied in C3H mice. The activity of 239 Pu in the conceptus was measured 24 hrs after the intravenous injection of 239 Pu citrate on days 10.5 to 16.5 of gestation. More 239 Pu was transferred to the conceptus when the plutonium was administered in the later stages of gestation; 0.12% of the injected dose per conceptus on day 10.5 and 1.3% on day 16.5. In all the gestational stages examined, the yolk sac and decidua contained more than 89% of the total activity distributed in the conceptus. The concentration of 239 Pu in the yolk sac was about two orders of magnitude greater than that in the fetus. The 239 Pu concentration in the maternal liver decreased with the gestational stage. In the early gestational stages the concentration in the maternal liver was greater than that in the yolk sac; but, this relationship was reversed in the later stages. (author)

Observations of surface-mediated reduction of Pu(VI) to Pu(IV) on hematite nanoparticles by ATR FT-IR

Energy Technology Data Exchange (ETDEWEB)

Emerson, Hilary P. [Florida International Univ., Applied Research Center, Miami, FL (United States); Powell, Brian A. [Clemson Univ., Dept. of Enviromental Engineering and Earth Sciences, Anderson, SC (United States)

2015-07-01

Previous studies have shown that mineral surfaces may facilitate the reduction of plutonium though the mechanisms of the reduction are still unknown. The objective of this study is to use batch sorption and attenuated total reflectance Fourier transform infrared spectroscopy experiments to observe the surface-mediated reduction of plutonium on hematite nanoparticles. These techniques allow for in situ measurement of reduction of plutonium with time and may lead to a better understanding of the mechanisms of surface mediated reduction of plutonium. For the first time, ATR FT-IR peaks for Pu(VI) sorbed to hematite are measured at ∝ 916 cm{sup -1}, respectively. The decrease in peak intensity with time provides a real-time, direct measurement of Pu(VI) reduction on the hematite surface. In this work pseudo first order rate constants estimated at the high loadings (22 mg{sub Pu}/g{sub hematite}, 1.34 x 10{sup -6} M{sub Pu}/m{sup 2}) for ATR FT-IR are approximately 10 x slower than at trace concentrations based on previous work. It is proposed that the reduced rate constant at higher Pu loadings occurs after the reduction capacity due to trace Fe(II) has been exhausted and is dependent on the oxidation of water and possibly electron shuttling based on the semiconducting nature of hematite. Therefore, the reduction rate at higher loadings is possibly due to the thermodynamic favorability of Pu(IV)-hydroxide complexes.

Ga-Ga bonding and tunnel framework in the new Zintl phase Ba{sub 3}Ga{sub 4}Sb{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Park, S -M; Kim, S -J; Kanatzidis, M G

2003-11-01

A new Zintl phase Ba{sub 3}Ga{sub 4}Sb{sub 5} was obtained from the reaction of Ba and Sb in excess Ga flux at 1000 deg. C, and its structure was determined with single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group Pnma (No. 62) with a=13.248(3) A, b=4.5085(9) A, c=24.374(5) A and Z=4. Ba{sub 3}Ga{sub 4}Sb{sub 5} has a three-dimensional [Ga{sub 4}Sb{sub 5}]{sup 6-} framework featuring large tunnels running along the b-axis and accommodating the Ba ions. The structure also has small tube-like tunnels of pentagonal and rhombic cross-sections. The structure contains ethane-like dimeric Sb{sub 3}Ga-GaSb{sub 3} units and GaSb{sub 4} tetrahedra that are connected to form 12- and 14-membered tunnels. Band structure calculations confirm that the material is a semiconductor and indicate that the structure is stabilized by strong Ga-Ga covalent bonding interactions.

Economical Production of Pu-238

Energy Technology Data Exchange (ETDEWEB)

Steven D. Howe; Douglas Crawford; Jorge Navarro; Terry Ring

2013-02-01

All space exploration missions traveling beyond Jupiter must use radioisotopic power sources for electrical power. The best isotope to power these sources is plutonium-238. The US supply of Pu-238 is almost exhausted and will be gone within the next decade. The Department of Energy has initiated a production program with a $10M allocation from NASA but the cost is estimated at over $100 M to get to production levels. The Center for Space Nuclear Research has conceived of a potentially better process to produce Pu-238 earlier and for significantly less cost. The new process will also produce dramatically less waste. Potentially, the front end costs could be provided by private industry such that the government only had to pay for the product produced. Under a NASA Phase I NIAC grant, the CSNR has evaluated the feasibility of using a low power, commercially available nuclear reactor to produce at least 1.5 kg of Pu-238 per year. The impact on the neutronics of the reactor have been assessed, the amount of Neptunium target material estimated, and the production rates calculated. In addition, the size of the post-irradiation processing facility has been established. In addition, a new method for fabricating the Pu-238 product into the form used for power sources has been identified to reduce the cost of the final product. In short, the concept appears to be viable, can produce the amount of Pu-238 needed to support the NASA missions, can be available within a few years, and will cost significantly less than the current DOE program.

Evaluating 239Pu levels using field detectors

International Nuclear Information System (INIS)

Wahl, L.E.; Smith, W.J. II; Martin, B.

1996-01-01

At Los Alamos National Laboratory, cleanup was planned at three septic tanks where surface soil in the outfall drainage areas was found to be contaminated with 239 Pu. To meet budget and deadline constraints, a technique was developed that used field instruments to verify 239 Pu soil contamination at levels less than 2.8 Bq g -1 , the established cleanup level. The drainage areas were surveyed using a low-energy gamma probe to identify likely areas of 239 Pu contamination. Between 40 and 135 0.1-min gamma radiation measurements were obtained from each drainage area. From these data, locations were identified for subsequent screening for alpha radioactivity. Soil samples from between 11 and 18 locations at each drainage area were placed in petri dishes, dried, and counted for 10 minutes using an alpha probe. Alpha counts were then related to 239 Pu concentrations using a curve developed from local soils containing known concentrations of 239 Pu. Up to six soil samples from each drainage area, representing a range of alpha radioactivity levels, were sent for laboratory analysis of isotopic plutonium to confirm field measurement results. Analytical and field results correlated well at all but one outfall area. At this area, field measurements predicted more 239 Pu than was measured in the laboratory, indicating the presence of another alpha-emitting radionuclide that might have been missed if only laboratory analyses for plutonium had been used. This technique, which combined a large number of gamma radioactivity measurements, a moderate number of alpha radioactivity measurements, and a few isotopic plutonium measurements, allowed quick and inexpensive comparison of 239 Pu with the cleanup level

PU.1 silencing leads to terminal differentiation of erythroleukemia cells

International Nuclear Information System (INIS)

Atar, Orna; Levi, Ben-Zion

2005-01-01

The transcription factor PU.1 plays a central role in development and differentiation of hematopoietic cells. Evidence from PU.1 knockout mice indicates a pivotal role for PU.1 in myeloid lineage and B-lymphocyte development. In addition, PU.1 is a key player in the development of Friend erythroleukemia disease, which is characterized by proliferation and differentiation arrest of proerythrocytes. To study the role of PU.1 in erythroleukemia, we have used murine erythroleukemia cells, isolated from Friend virus-infected mice. Expression of PU.1 small interfering RNA in these cells led to significant inhibition of PU.1 levels. This was accompanied by inhibition of proliferation and restoration in the ability of the proerythroblastic cells to produce hemoglobin, i.e., reversion of the leukemic phenotype. The data suggest that overexpression of PU.1 gene is the immediate cause for maintaining the leukemic phenotype of the disease by retaining the self-renewal capacity of transformed erythroblastic cells and by blocking the terminal differentiation program towards erythrocytes

Multilayer self-organization of InGaAs quantum wires on GaAs surfaces

International Nuclear Information System (INIS)

Wang, Zhiming M.; Kunets, Vasyl P.; Xie, Yanze Z.; Schmidbauer, Martin; Dorogan, Vitaliy G.; Mazur, Yuriy I.; Salamo, Gregory J.

2010-01-01

Molecular-Beam Epitaxy growth of multiple In 0.4 Ga 0.6 As layers on GaAs (311)A and GaAs (331)A has been investigated by Atomic Force Microscopy and Photoluminescence. On GaAs (311)A, uniformly distributed In 0.4 Ga 0.6 As quantum wires (QWRs) with wider lateral separation were achieved, presenting a significant improvement in comparison with the result on single layer [H. Wen, Z.M. Wang, G.J. Salamo, Appl. Phys. Lett. 84 (2004) 1756]. On GaAs (331)A, In 0.4 Ga 0.6 As QWRs were revealed to be much straighter than in the previous report on multilayer growth [Z. Gong, Z. Niu, Z. Fang, Nanotechnology 17 (2006) 1140]. These observations are discussed in terms of the strain-field interaction among multilayers, enhancement of surface mobility at high temperature, and surface stability of GaAs (311)A and (331)A surfaces.

Preparation and characterization of 238Pu-ceramics for radiation damage experiments

International Nuclear Information System (INIS)

DM Strachan; RD Scheele; WC Buchmiller; JD Vienna; RL Sell; RJ Elovich

2000-01-01

As a result of treaty agreements between Russia and the US, portions of their respective plutonium and nuclear weapons stockpiles have been declared excess. In support of the US Department of Energy's 1998 decision to pursue immobilization of a portion of the remaining Pu in a titanate-based ceramic, the authors prepared nearly 200 radiation-damage test specimens of five Pu- and 238 Pu-ceramics containing 10 mass% Pu to determine the effects of irradiation from the contained Pu and U on the ceramic. The five Pu-ceramics were (1) phase-pure pyrochlore [ideally, Ca(U, Pu)Ti 2 O 7 ], (2) pyrochlore-rich baseline, (3) pyrochlore-rich baseline with impurities, (4) phase-pure zirconolite [ideally Ca(U, Pu)Ti 2 O 7 ], and (5) a zirconolite-rich baseline. These ceramics were prepared with either normal weapons-grade Pu, which is predominantly 239 Pu, or 238 Pu. The 238 Pu accelerates the radiation damage relative to the 239 Pu because of its much higher specific activity. The authors were unsuccessful in preparing phase-pure (Pu, U) brannerite, which is the third crystalline phase present in the baseline immobilization form. Since these materials will contain ∼10 mass% Pu and about 20 mass% U, radiation damage to the crystalline structure of these materials will occur overtime. As the material becomes damaged from the decay of the Pu and U, it is possible for the material to swell as both the alpha particles and recoiling atoms rupture chemical bonds within the solid. As the material changes density, cracking, perhaps in the form of microcracks, may occur. If cracking occurs in ceramic that has been placed in a repository, the calculated rate of radionuclide release if the can has corroded would increase proportionately to the increase in surface area. To investigate the effects of radiation damage on the five ceramics prepared, the authors are storing the specimens at 20, 125, and 250 C until the 238 Pu specimens become metamict and the damage saturates. They will

Antinociceptive activity of Delta9-tetrahydrocannabinol non-ionic microemulsions.

Science.gov (United States)

Lazzari, P; Fadda, P; Marchese, G; Casu, G L; Pani, L

2010-06-30

Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the major psychoactive constituent of Cannabis sativa L., has been widely studied for its potential pharmaceutical application in the treatment of various diseases and disturbs. This sparingly soluble terpeno-phenolic compound is not easy to handle and to be formulated in pharmaceutical preparations. The aim of this work was to develop a stable aqueous Delta(9)-THC formulation acceptable for different ways of administration, and to evaluate the therapeutic properties of the new Delta(9)-THC based preparation for pain treatment. Due to the thermodynamic stability and advantages of microemulsion based systems, the study was focused on the identification of aqueous microemulsion based systems containing Delta(9)-THC. Oil in water Delta(9)-THC microemulsions were individuated through phase diagrams construction, using the non-ionic surfactant Solutol HS15, being this surfactant acceptable for parenteral administration in human. A selected microemulsion samples containing 0.2 wt% of Delta(9)-THC, stable up to 52 degrees C, was successfully assayed on animal models of pain. Significant antinociceptive activity has been detected by both intraperitoneal and intragastric administration of the new Delta(9)-THC pharmaceutical preparation. The effect has been highlighted in shorter time if compared to a preparation of the same active principle based on previously reported conventional preparation. 2010 Elsevier B.V. All rights reserved.

Delta (1232) Dalitz decay in proton-proton collisions at T=1.25 GeV measured with HADES at GSI

Czech Academy of Sciences Publication Activity Database

Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Chlad, Lukáš; Kugler, Andrej; Rodriguez Ramos, Pablo; Sobolev, Yuri, G.; Svoboda, Ondřej; Tlustý, Pavel; Wagner, Vladimír

2017-01-01

Roč. 95, č. 6 (2017), č. článku 065205. ISSN 2469-9985 R&D Projects: GA ČR GA13-06759S Institutional support: RVO:61389005 Keywords : HADES collaboration * heavy ion collisions * Delta(1232) Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 3.820, year: 2016

Contribution to the study of U-Ti and U-Pu-Ti carbides; Contribution a l'etude des carbures U-C-Ti et (U, Pu) - C-Ti

Energy Technology Data Exchange (ETDEWEB)

Milet, C A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

After having discussed the reasons to use (U,Pu) carbides as fast reactor fuel, we examine the influence of the addition of titanium to these carbides. A preliminary study has been done on the system of U-C-Ti and some properties have been measured such as: density, thermal expansion, electrical resistivity, atmospheric corrosion and compatibility with stainless steel. The systems U-Pu-C-Ti (Pu/U + Pu equal to 15 per cent) and U-C-Ti have been found to be very similar. There exists a two phases region (U,Pu)C + TiC, an eutectic between (U,Pu)C and TiC for approximately 15 at %. The solubilities of U + Pu in TiC and of Ti in (U,Pu)C is less than 1 % at. The addition of titanium does not markedly change thermal expansion coefficients of (U,Pu)C. However the resistance to atmospheric corrosion and compatibility with stainless steel is improved. Thermal conductivity, calculated from electrical resistivity, has increased. On the other side, the density of fissile material is lowered. The combination of (U,Pu)C + TiC seems to be the most promising alloy for application as nuclear fuel. (author) [French] Apres avoir rappele les problemes poses par un combustible pour les reacteurs a neutrons rapides et l'interet des carbures U-Pu-C comme combustible, on examine l'influence de l'addition de titane dans ces carbures. Une etude preliminaire sur le systeme U-C-Ti a ete effectuee et quelques proprietes sont indiquees: densite, coefficients de dilatation, resistivite electrique, tenue a la corrosion atmospherique, compatibilite avec l'acier inoxydable. Le systeme U-Pu-C-Ti (Pu/U + Pu egal a 15 pour cent) presente de grandes analogies avec le systeme U-C-Ti. Il existe un domaine biphase (U,Pu)C + TiC, un eutectique entre (U,Pu)C et TiC pour environ 15 at % Ti; les solubilites de U + Pu clans TiC et de Ti dans (U,Pu)C sont inferieures a 1 at %. Par rapport a la phase (U,Pu)C, l'addition de titane est sans effets importants sur les coefficients de dilatation. Par contre la tenue a

Phase equilibrium of PuO2-x - Pu2O3 based on first-principles calculations and configurational entropy change

International Nuclear Information System (INIS)

Minamoto, Satoshi; Kato, Masato; Konashi, Kenji

2011-01-01

Combination of an oxygen vacancy formation energy calculated using first-principles approach and the configurational entropy change treated within the framework of statistical mechanics gives an expression of the Gibbs free energy at large deviation from stoichiometry of plutonium oxide PuO 2 . An oxygen vacancy formation energy 4.20 eV derived from our previously first-principles calculation was used to evaluate the Gibbs free energy change due to oxygen vacancies in the crystal. The oxygen partial pressures then can be evaluated from the change of the free energy with two fitting parameters (a vacancy-vacancy interaction energy and vibration entropy change due to induced vacancies). Derived thermodynamic expression for the free energy based on the SGTE thermodynamic data for the stoichiometric PuO 2 and the Pu 2 O 3 compounds was further incorporated into the CALPHAD modeling, then phase equilibrium between the stoichiometric Pu 2 O 3 and non-stoichiometric PuO 2-x were reproduced.

A Novel Sigma-Delta Modulator with Fractional-Order Digital Loop Integrator

Directory of Open Access Journals (Sweden)

Chi Xu

2017-01-01

Full Text Available This paper proposes using a fractional-order digital loop integrator to improve the robust stability of Sigma-Delta modulator, thus extending the integer-order Sigma-Delta modulator to a non-integer-order (fractional-order one in the Sigma-Delta ADC design field. The proposed fractional-order Sigma-Delta modulator has reasonable noise characteristics, dynamic range, and bandwidth; moreover the signal-to-noise ratio (SNR is improved remarkably. In particular, a 2nd-order digital loop integrator and a digital PIλDμ controller are combined to work as the fractional-order digital loop integrator, which is realized using FPGA; this will reduce the ASIC analog circuit layout design and chip testing difficulties. The parameters of the proposed fractional-order Sigma-Delta modulator are tuned by using swarm intelligent algorithm, which offers opportunity to simplify the process of tuning parameters and further improve the noise performance. Simulation results are given and they demonstrate the efficiency of the proposed fractional-order Sigma-Delta modulator.

Perturbation in the 240Pu/239Pu global fallout ratio in local sediment following the nuclear accidents at Thule (Greenland) and Palomares (Spain)

International Nuclear Information System (INIS)

Mitchell, P.I.; Vintro, L.L.; Gasco, C.; Sanchez-Cabeza, J.A.

1995-01-01

It is well established that the main source of the plutonium found in marine sediments throughout the Northern Hemisphere is global stratospheric fallout, characterized by a typical 240 Pu/ 239 Pu atom ratio of ∼0.18. Measurements of perturbations in this ratio at various sites which had been subjected to close-in fallout, mainly from surface-based testing, has confirmed the feasibility of using this ratio to distinguish plutonium from different fallout sources. In the present study, the 240 Pu/ 239 Pu ratio has been examined in samples of sediment collected at Thule (Greenland) and Palomares (Spain), where accidents involving the release and dispersion of plutonium from fractured nuclear weapons occurred in 1968 and 1966, respectively. The 240 Pu/ 239 Pu ratio was measured by high-resolution alpha spectrometry and spectral deconvolution. The analytical results showed that at Thule the mean 240 Pu/ 239 Pu atom ratio was 0.033±0.004, while at Palomares the equivalent ratio appeared to be significantly higher at 0.056±0.003. Both ratios are consistent with those reported for soils samples at the Nevada site and Nagasaki, and are clearly indicative of weapons-grade plutonium. 27 refs., 1 fig., 2 tabs

Contribution to the study of the (U,Pu)C,N system; Contribution a l'etude du systeme (U,Pu)C,N

Energy Technology Data Exchange (ETDEWEB)

Lorenzelli, R [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

The reactions of UC, PuC, (U,Pu)C, UC{sub 2} and U(C{sub 1-x}O{sub x}) with nitrogen at moderate temperatures (room temperature to 400 C) are described. The influence of the uptake of nitrogen by the powders necessary to sinter the carbides upon the nature of the final product has been investigated; it has been shown that the sintered carbides are hyper-stoichiometric. The reactions of carbon with UN, PuN and (U,Pu)N has also been studied. Under vacuum, carbon reacts on the nitrides at temperatures as low as 1100 C; nitrogen is replaced by carbon and the final product is a carbonitride. The reaction is: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. The reaction is limited and the carbonitrides have a fixed composition in presence of M{sub 2}C{sub 3} or MC{sub 2}; hence it is impossible to produce pure MC using the reaction. The ternary diagram U-C-N, Pu-C-N and (U,Pu)C-N have been drawn. They show clearly that it is possible to obtain single phase carbonitrides in a wide domain of compositions. (author) [French] On decrit les reactions avec l'azote de UC, PuC,(U,Pu)C,UC{sub 2} et U(C{sub 1-x}O{sub x}), par action directe de l'azote a temperature moderee (de l'ambiante a 450 C). On a etudie l'influence de la contamination par l'azote des poudres de carbures necessaires au frittage sur la nature des produits frittes; on a montre que les carbures frittes obtenus sont hyperstoechiometriques. On a etudie parallelement les reactions du carbone avec UN, PuN et (U,Pu)N. Sous vide le carbone reagit sur les nitrures des 1100 C: le carbone se substitue a l'azote; l'azote libere est elimine et le produit final est un carbonitrure. La reaction s'ecrit: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. La reaction est limitee et les carbonitrures obtenus ont une composition limite fixe en presence des carbures superieurs M{sub 2}C{sub 3} et MC{sub 2}; il est donc impossible d'obtenir MC pur par cette reaction. Les diagrammes d'equilibre U-C-N, Pu-C-N et (U,Pu) C-N, ont

Effect of microdose distribution on chromosome aberration frequency in liver cells of the Chinese hamster following exposure to 239PuO2 or 238PuO2 particles

International Nuclear Information System (INIS)

Brooks, A.L.; Peters, R.F.; Retherford, J.C.

1974-01-01

Chinese hamsters were injected intravenously with 239 PuO 2 or 238 PuO 2 particles of known size or with 238 Pu citrate to determine the effect of particle size and specific activity on the frequency and distribution of chromosome damage in the liver. Three particle sizes were used in the 239 PuO 2 experiment: 0.15, 0.44, and 0.89 μm, and all animals were injected with a constant activity, 5 x 10 -4 muCi 239 Pu/gm body weight. The 238 PuO 2 was injected in three particle sizes, 0.17, 0.41, and 1.1 μm and at three activity levels. The 238 Pu citrate was injected at 5 x 10 -3 muCi 238 Pu/gm body weight. Hamsters injected with 239 PuO 2 were sacrificed at 15, 42, and 122 days after injection and those injected with either 238 PuO 2 or 238 Pu citrate were sacrificed 12 days after injection. The number of alpha tracks/star increased as a function of the particle size injected. A change in particle size with time was noted as smaller particles were aggregated into larger ones by the phagocytic action of Kupffer cells. Injection of 239 PuO 2 and 238 PuO 2 produced a distribution of chromosome damage which was non-poison in nature. 239 PuO 2 produced increased damage with increasing average dose with some cells containing a large number of aberrations, but there was relatively little particle size effect. Conversely, aberration frequencies after 238 PuO 2 injection were inversely related to particle size and no cells were seen with large amounts of damage. The 238 Pu citrate produced 6 x 10 -3 aberrations/cell/rad which was a higher rate than observed for 238 Pu particles. Risk for the production of cellular damage in the liver was greater per μCi following injection of either 238 Pu or 239 Pu citrate than it was following deposition of the same amount of 239 PuO 2 or 238 PuO 2 particles. (U.S.)

Road Maintenance Experience Using Polyurethane (PU) Foam Injection System and Geocrete Soil Stabilization as Ground Rehabilitation

Science.gov (United States)

Fakhar, A. M. M.; Asmaniza, A.

2016-07-01

There are many types of ground rehabilation and improvement that can be consider and implement in engineering construction works for soil improvement in order to prevent road profile deformation in later stage. However, when comes to road maintenance especially on operated expressways, not all method can be apply directly as it must comply to opreation's working window and lane closure basis. Key factors that considering ideal proposal for ground rehabilitation are time, cost, quality and most importantly practicality. It should provide long lifespan structure in order to reduce continuous cycle of maintenance. Thus, this paper will present two approaches for ground rehabilitation, namely Polyurethane (PU) Foam Injection System and Geocrete Soil Stabilization. The first approach is an injection system which consists two-parts chemical grout of Isocynate and Polyol when mixed together within soil structure through injection will polymerized with volume expansion. The strong expansion of grouting causes significant compression and compacting of the surrounding soil and subsequently improve ground properties and uplift sunken structure. The later is a cold in-place recyclying whereby mixture process that combines in-situ soil materials, cement, white powder (alkaline) additive and water to produce hard yet flexible and durable ground layer that act as solid foundation with improved bearing capacity. The improvement of the mechanical behaviour of soil through these two systems is investigated by an extensive testing programme which includes in-situ and laboratory test in determining properties such as strength, stiffness, compressibility, bearing capacity, differential settlement and etc.

Estimation of human gonadal Pu and Ce concentrations from animal data

International Nuclear Information System (INIS)

Thomas, R.G.; Durbin, P.W.; McInroy, J.F.; Healy, J.W.

1989-01-01

Data were obtained from the literature for gonad and body weights and for the Pu or Ce content of the gonads and body at death for several laboratory animal species, five human Pu injection cases, and 731 human adults exposed environmentally to Pu in fallout. Data for Pu concentration in gonads, liver, and bone samples of 59 male and five female occupational Pu cases (including four completely analyzed whole bodies) were obtained from the U.S. Transuranium Registry. A logarithmic function was used to relate fractional Pu or Ce concentration in testes and ovaries to body weight of the animals and to predict fractional Pu or Ce concentrations in human gonads, [Pu]G . PuB-1 = aBWb, where [Pu]G or [Ce]G is the nuclide concentration in gonads (Bq g-1 of wet weight), PuB or CeB is the nuclide content of the body at death, and BW is body weight (kg). The fractional Pu and Ce concentrations in both the testes and ovaries are inverse and nearly linear functions of body weight. The regression lines of fractional Pu or Ce concentration in testes and ovaries have similar slopes (b = -1.07 +/- 0.14); however, the nuclide concentrations (coefficient a) in ovaries are six times greater than in testes. Extrapolation of the animal data yielded fractional Pu concentrations in human testes and ovaries that agree with those calculated for the occupational cases and those recommended by the International Commission on Radiological Protection. The good agreement between the fractional concentrations of Pu and Ce in the testes and in the ovaries suggests that these data can be substituted in metabolic models of chemically similar elements for which gonadal data are scarce

Effect of tissue-specific acetylcholinesterase inhibitor C-547 on alpha 3 beta 4 and alpha beta epsilon delta acetylcholine receptors in COS cells

Czech Academy of Sciences Publication Activity Database

Lindovský, Jiří; Petrov, K.; Krůšek, Jan; Reznik, V.S.; Nikolsky, E. E.; Vyskočil, František

2012-01-01

Roč. 688, 1-3 (2012), s. 22-26 ISSN 0014-2999 R&D Projects: GA MŠk(CZ) LC554; GA ČR(CZ) GA202/09/0806; GA AV ČR(CZ) IAA500110905; GA AV ČR(CZ) IAA100110501; GA AV ČR(CZ) IAA5011411 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : nicotinic ACh receptor * alpha 3 beta 4 * alpha beta epsilon delta * C-547 * anti-cholinesterase Subject RIV: ED - Physiology Impact factor: 2.592, year: 2012

Direct reduction of 238PuO2 and 239PuO2 to metal

International Nuclear Information System (INIS)

Mullins, L.J.; Foxx, C.L.

1982-02-01

The process for reducing 700 g 239 PuO 2 to metal is a standard procedure at Los Alamos National Laboratory. This process is based on research for reducing 200 g 238 PuO 2 to metal. This report describes in detail the experiments and development of the 200-g process. The procedure uses calcium metal as the reducing agent in a molten CaCl 2 solvent system. The process to convert impure plutonia to high-purity metal by oxide reduction followed by electrorefining is also described

A 233U/236U/242Pu/244Pu spike for isotopic and isotope dilution analysis by mass spectrometry with internal calibration

International Nuclear Information System (INIS)

Stepanov, A.; Belyaev, B.; Buljanitsa, L.

1989-11-01

The Khlopin Radium Institute prepared on behalf of the IAEA a synthetic mixture of 233 U, 236 U, 242 Pu and 244 Pu isotopes. The isotopic composition and elemental concentration of uranium and plutonium were certified on the basis of analyses done by four laboratories of the IAEA Network, using mass spectrometry with internal standardization. The certified values for 233 U/ 236 U ratio and the 236 U chemical concentration have a coefficient of variation of 0.05%. The latter is fixed by the uncertainty in the 235 U/ 238 U ratio of NBS500 used as internal standard. The coefficients of variation of the 244 Pu/ 242 Pu ratio and the 242 Pu chemical concentration are respectively 0.10% and 0.16% and limited by the uncertainty in the 240 Pu/ 239 Pu ratio of NBS947. This four isotope mixture was used as an internal standard as well as a spike, to analyze 30 batches of LWR spent fuel solutions. The repeatability of the mass spectrometric measurements have a coefficient of variation of 0.025% for the uranium concentration, and of 0.039% for the plutonium concentration. The spiking and treatment errors had a coefficient of variation of 0.048%. (author). Refs, figs and tabs

Radioimmunodetection of tumor with Ga-67 labeled antibodies

International Nuclear Information System (INIS)

Furukawa, Takako; Endo, Keigo; Ohmomo, Yoshiro

1986-01-01

Antibodies against tumor associated antigen; anti-AFP polyclonal antibody, anti-thyroglobulin monoclonal antibody and anti-hCG monoclonal antibody, were labeled with Ga-67, using deferoxamine (DF) as a bifunctional chelating agent. The immunoreactivity and in vivo stability of the Ga-67 labeled antibodies were examined. The effect of DF conjugation to antibodies on the antigen-binding activity was evaluated by RIA and Scatchard analysis or tanned sheep red blood cell hemagglutination technique. When DF was conjugated to antibody at the molar ratio of 1 : 1, the antibody activity of the DF-conjugated antibodies was fully retained. Whereas, in heavily conjugated antibodies, the maximum antigen binding capacity was reduced. Biodistribution study in normal mice demonstrated the high in vivo stability of Ga-67 labeled antibodies. The labeling of DF-antibody conjugated with Ga-67 was performed easily and quickly, with a high labeling efficiency, requiring no further purification. Thus, this labeling method, providing in vivo stability of Ga-67 labeled antibody and full retention of immunoreactivity, would be useful for the radioimmunodetection of various cancers. (author)

Vertical distribution of 241Pu in the southern Baltic Sea sediments

International Nuclear Information System (INIS)

Strumińska-Parulska, Dagmara I.

2014-01-01

Highlights: • The unique study on 241 Pu in sediments from the southern Baltic Sea was presented. • 241 Pu was determined using alpha spectrometry by indirect method. • The biggest amount of 241 Pu existed in the surface layers of all analyzed sediments. • The highest 241 Pu amount comes from the Chernobyl accident. - Abstract: The vertical distribution of plutonium 241 Pu in marine sediments can assist in determining the deposition history and sedimentation process of analyzed regions. In addition, 241 Pu/ 239+240 Pu activity ratio could be used as a sensitive fingerprint for radioactive source identification. The present preliminary studies on vertical distribution of 241 Pu in sediments from four regions of the southern Baltic Sea are presented. The distribution of 241 Pu was not uniform and depended on sediment geomorphology and depth as well as location. The highest concentrations of plutonium were found in the surface layers of all analyzed sediments and originated from the Chernobyl accident

The production of {sup 238-242}Pu(n,γ){sup 239-243}Pu fissionable fluids in a fusion-fission hybrid reactor

Energy Technology Data Exchange (ETDEWEB)

Guenay, Mehtap [Inoenue Univ., Malatya (Turkey). Physics Dept.

2014-03-15

In this study, the effect of spent fuel grade plutonium content on {sup 239-243}Pu was investigated in a designed hybrid reactor system. In this system, the fluids were composed of a molten salt, heavy metal mixture with increased mole fractions 99-95 % Li{sub 20}Sn{sub 80}-1-5 % SFG-Pu, 99-95 % Li{sub 20}Sn{sub 80}-1-5 % SFG-PuF{sub 4}, 99-95 % Li{sub 20}Sn{sub 80}-1-5 % SFG-PuO{sub 2}. Beryllium (Be) is a neutron multiplier by (n,2n) reactions. Thence, a Be zone of 3 cm thickness was used in order to contribute to fissile fuel breeding between the liquid first wall and a 9Cr2WVTa ferritic steel blanket which is used as structural material. The production of {sup 238-242}Pu(n,γ){sup 239-243}Pu was calculated in liquid first wall, blanket and shielding zones. Three-dimensional nucleonic calculations were performed by using the most recent version MCNPX-2.7.0 Monte Carlo code and nuclear data library ENDF/B-VII.0. (orig.)

Crystallization kinetics, glass transition kinetics, and thermal stability of Se70-xGa30Inx (x=5, 10, 15, and 20) semiconducting glasses

International Nuclear Information System (INIS)

Imran, Mousa M.A.

2011-01-01

Crystallization and glass transition kinetics of Se 70-x Ga 30 In x (x=5, 10, 15, and 20) semiconducting chalcogenide glasses were studied under non-isothermal condition using a Differential Scanning Calorimeter (DSC). DSC thermograms of the samples were recorded at four different heating rates 5, 10, 15, and 20 K/min. The variation of the glass transition temperature (T g ) with the heating rate (β) was used to calculate the glass transition activation energy (E t ) using two different models. Meanwhile, the variation of the peak temperature of crystallization (T p ) with β was utilized to deduce the crystallization activation energy (E c ) using Kissinger, Augis-Bennet, and Takhor models. Results reveal that E t decreases with increasing In content, while both T g and E c exhibit the opposite behavior, and the crystal growth occurs in one dimension. The variation of these thermal parameters with the average coordination number was also discussed, and the results were interpreted in terms of the type of bonding that In makes with Se. Assessment of thermal stability and glass forming ability (GFA) was carried out on the basis of some quantitative criteria and the results indicate that thermal stability is enhanced while the crystallization rate is reduced with the addition of In to Se-Ga glass. -- Research highlights: → Addition of In to Se-Ga glass decreases the glass transition activation energy. → The crystallization rate in Se-Ga-In glass is reduced as In content increases. → The crystal growth in Se-Ga-In glass occurs in one dimension. → Thermal properties of Se-Ga-In glass indicate a shift in Phillips-Thorpe threshold.

238Pu fuel form activities, March 1-September 30, 1985

International Nuclear Information System (INIS)

1986-01-01

The SRP portion of this report summarizes production 238 PuO 2 fuel forms for use in radioisotopic thermoelectric generators (RTG's) in the Plutonium Fuel Form (PuFF) Facility at the Savannah River Plant. The PuFF Facility began producing iridium-encapsulated, 62.5-watt 238 PuO 2 right circular cylinders for GPHS (General Purpose Heat Source) RTG's in June 1980; this program was completed in December 1983. The PuFF Facility has been placed in a production readiness mode of operation pending funding of additional heat source programs

Surrogate 239Pu(n, fxn) and 241Pu(n, fxn) average fission-neutron-multiplicity measurements

Energy Technology Data Exchange (ETDEWEB)

Burke, J. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alan, B. S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Akindele, O. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Casperson, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hughes, R. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fisher, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-09-26

We have constructed a new neutron-charged-particle detector array called NeutronSTARS. It has been described extensively in LLNL-TR-703909 [1] and Akindele et al [2]. We have used this new neutron-charged-particle array to measure the 241Pu and 239Pu fissionneutron multiplicity as a function of equivalent incident-neutron energy from 100 keV to 20 MeV. The experimental approach, detector array, data analysis, and results are summarized in the following sections.

Evaluation of in vivo stability of Ga-67 labeled human fibrinogen

International Nuclear Information System (INIS)

Takahashi, Keietsu; Takahashi, Jun; Okano, Sakae; Kurami, Miki; Ueda, Nobuo; Hazue, Masaaki

1987-01-01

Human fibrinogen (Fib) was conjugated with a large number of deferoxamine (DFO) through dialdehyde starch (DAS), and the conjugate (Fib-DAS-DFO) was labeled with Ga-67. Thus labeled fibrinogen (Ga-67-Fib-DAS-DFO) showed a high labeling efficiency (more than 90 %) and retained clottability (more than 80 %). For the evaluation of plasma radioactive species, blood samples were collected at various time periods after the i.v. administration of Ga-67-Fib-DAS-DFO into rats, and the plasma radioactivity was analyzed by high performance liquid chromatography (HPLC) and electrophoresis (EP). The radioactive HPLC elution profiles for the plasma samples were identical with that of the original Ga-67-Fib-DAS-DFO; the EP patterns for the plasma were also identical with the original one, and no radioactive species, except for Ga-67-Fib-DAS-DFO, was detected by HPLC or EP. Furthermore, the presence of transferrin in the labeling formulation did not affect the labeling yield of Ga-67-Fib-DAS-DFO indicating that the transchelation of Ga-67 from DFO on Fib to transferrin is negligible. These findings indicated that Ga-67 is tightly bound to Fib-DAS-DFO in blood, and the Ga-67-Fib-DAS-DFO can be efficiently trapped by clots as the result of its high retention of physiological activities as fibrinogen. (author)

Bifurcation routes and economic stability

Czech Academy of Sciences Publication Activity Database

Vošvrda, Miloslav

2001-01-01

Roč. 8, č. 14 (2001), s. 43-59 ISSN 1212-074X R&D Projects: GA ČR GA402/00/0439; GA ČR GA402/01/0034; GA ČR GA402/01/0539 Institutional research plan: AV0Z1075907 Keywords : macroeconomic stability * foreign investment phenomenon * the Hopf bifurcation Subject RIV: AH - Economics

Internal Corrosion Analysis of Model 9975 Packaging Containing Pu or PuO2 During Shipping and Storage

International Nuclear Information System (INIS)

Vormelker, P.

1999-01-01

The Materials Consultation Group of SRTC has completed an internal corrosion analysis of the Model 9975 packaging assembly containing either Pu or PuO2 for storage in K Reactor under ambient conditions for a period of 12 years. The 12-year storage period includes two years for shipping and up to ten years for storage

Pu(V) as the stable form of oxidized plutonium in natural waters

International Nuclear Information System (INIS)

Orlandini, K.A.; Penrose, W.R.; Nelson, D.M.

1986-01-01

This work presents analytical evidence supporting the proposition that Pu(V) is the sole or predominant form of oxidized plutonium in natural waters. Two independent methods, the selective adsorption of Pu(VI) by silica gel, and the somewhat less selective coprecipitation of Pu(V) with calcium carbonate, were developed to separate Pu(V) from Pu(VI). Measurements of ambient plutonium in several natural waters by these methods found only Pu(V). In laboratory tracer studies, Pu(VI) was shown to be highly unstable in dilute bicarbonate solution and in Lake Michigan water, reducing in first-order fashion to Pu(V). (orig.)

Determination of Pu and U by ICP-MS

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, Y.; Yoshida, S. [National Inst. of Radiological Sciences, Chiba (Japan)

2002-06-01

In order to understand the distribution and behaviour of long-lived radionuclides in the terrestrial environment, we have developed analytical methods for {sup 238}U, {sup 232}Th and {sup 239},{sup 240}Pu and determined them in several environmental samples. ICP-MS was applied to the analyses. Concentrations of {sup 238}U and {sup 232}Th were determined in variety of soils, plants and environmental waters. The mean concentration of U and Th in 77 soils, collected several parts of Japan, were 2.3 and 7.0 ppm (dry wt). Red and yellow soils, which are mainly found in western Japan, have high concentrations of Th, suggesting the contribution from granitic rocks. Higher concentration of U in agricultural soils than forest soils suggested the possible accumulation of this element from phosphate fertilizer. The soil-to-plant transfer factors (concentration ratios between plants and soils) of U and Th were estimated from the analytical results of these nuclides in soils and in several crops. The factors for U were about 0.0005 in leaf vegetables, 0.0002 in root vegetables, 0.0001 in potatoes and 0.00001 in rice (polished). For Th, the factors were about 0.0005 in leaf vegetables, 0.0008 in root vegetables, 0.0005 in potatoes and 0.00003 in rice (polished). For the analysis of plutonium, chromatographic resin, Dowex 1x8, was examined for their applicability in the separation of Pu from the matrix elements. Sufficient decontamination factors (10{sup 4}-10{sup 5}) for many matrix elements including U, which interferes in the detection of mass 239, were obtained in both resins. Analytical results of {sup 239+240}Pu in standard reference materials (IAEA-135, -SOIL-6, -368 and -134) indicated that the accuracy of this method was satisfactory. Data on the {sup 240}Pu/{sup 239}Pu atom ratios in these reference materials, which are rare in the literature, were also obtained. Soil samples from the Marshall Islands showed a large variation of the {sup 240}Pu/{sup 239}Pu atom ratios

Intergranular corrosion behavior associated with delta-ferrite transformation of Ti-modified Super304H austenitic stainless steel

International Nuclear Information System (INIS)

Bai, Guanshun; Lu, Shanping; Li, Dianzhong; Li, Yiyi

2015-01-01

Highlights: • Relationship between delta-ferrite transformation and IGC behavior was evaluated by DL-EPR test quantitatively. • The IGC site at austenite/ferrite grain boundary changes with aging time at 650 °C. • A higher fraction of delta-ferrite with poor stability increases the IGC sensitisation. • Self-healing of IGC was mainly induced by the Cr diffusion from primary austenite rather than the delta-ferrite. - Abstract: A double loop electrochemical potentiokinetic reactivation (DL-EPR) test was conducted to investigate the relationship between the evolution of delta-ferrite and the intergranular corrosion (IGC) of Ti-modified Super304H, which was aged at 650 °C for 4–500 h. Scanning electron microscopy and transmission electron microscopy were adopted to analyze the evolution of delta-ferrite. The results indicated that a higher fraction of delta-ferrite with poor stability increased the IGC sensitisation of Ti-modified Super304H. Moreover, the self-healing of the sensitisation of Ti-modified Super304H occurred after 48 h due to the diffusion of chromium atoms mainly from the adjacent primary austenite rather than the delta-ferrite

Status of 239Pu evaluations

International Nuclear Information System (INIS)

Kawano, Toshihiko; Talou, Patrick; Chadwick, Mark B.

2014-01-01

This paper summarises the current status of nuclear data evaluations for n+ 239 Pu. The nuclear data we address include fission, capture, scattering cross-sections, as well as the prompt fission neutron energy spectrum, which has large sensitivities to the criticality benchmark testing. The evaluated nuclear data files currently available for 239 Pu are compared, and the source of differences in the cross-sections are discussed. Some open questions on the statistical model calculations for deformed systems are also given. (authors)

Water Splitting over Epitaxially Grown InGaN Nanowires on-Metallic Titanium/Silicon Template: Reduced Interfacial Transfer Resistance and Improved Stability

KAUST Repository

Ebaid, Mohamed

2018-03-09

Water splitting using InGaN-based photocatalysts may have a great contribution in future renewable energy production systems. Among the most important parameters to solve are those related to substrate lattice-matching compatibility. Here, we directly grow InGaN nanowires (NWs) on a metallic Ti/Si template, for improving water splitting performance compared to a bare Si substrate. The open circuit potential of the epitaxially grown InGaN NWs on metallic Ti was almost two times that of those grown on Si substrate. The interfacial transfer resistance was also reduced significantly after introducing the metallic Ti interlayer. An applied-bias-photon-to-current conversion efficiency of 2.2% and almost unity Faradic efficiency for hydrogen generation were achieved using this approach. The InGaN NWs grown on Ti showed improved stability of hydrogen generation under continuous operation conditions, when compared to those grown on Si, emphasizing the role of the semiconductor-on-metal approach in enhancing the overall efficiency of water splitting catalysts.

Stability with temperature of mixed uranium plutonium monocarbides

International Nuclear Information System (INIS)

Riglet-Martial, Ch.; Dumas, J.C.; Piron, J.P.; Gueneau, Ch.

2008-01-01

Full text: Among the different advanced fuel materials of concern for Generation IV systems, the mixed carbide of uranium and plutonium fuel is considered as one of the key materials for Gas Fast Reactors (GFR) systems. For purposes of optimising its fabrication process as well as its performances in various operating conditions, the losses of gaseous plutonium specially at elevated temperatures have to be controlled and minimized. The paper is therefore concerned with a parametric analysis of the stability with temperature of mixed carbides of uranium and plutonium. Previous published experimental studies have shown that mixed (U ,Pu) carbides undergo a highly incongruent sublimation at high temperatures: the vapour phase in equilibrium with the solid is mainly composed of gaseous plutonium (P Pu /P total > 99 % ) while the contribution of gaseous U and C remains very low. The composition of the system U 1-z Pu z C 1+x ' (z =Pu/(U+Pu) and x C/(U+Pu)), the temperature (T) and the expansion volume (V) of the gas are the main parameters in the loss of gaseous Pu. The calculations are carried out using the SAGE (Solgasmix Advanced Gibbs Energy) software, by assuming ideal solid solutions between UC and PuC, as well as between U 2 C 3 and Pu 2 C 3 . The validity of the model is previously tested using published equilibrium vapour pressure data. This work gives rise to a large description of the variations of Pu losses from mixed uranium plutonium carbides and leads to some basic recommendations in connection with the use of this advanced fuel materials

Contribution to the study of the (U,Pu)C,N system; Contribution a l'etude du systeme (U,Pu)C,N

Energy Technology Data Exchange (ETDEWEB)

Lorenzelli, R. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

The reactions of UC, PuC, (U,Pu)C, UC{sub 2} and U(C{sub 1-x}O{sub x}) with nitrogen at moderate temperatures (room temperature to 400 C) are described. The influence of the uptake of nitrogen by the powders necessary to sinter the carbides upon the nature of the final product has been investigated; it has been shown that the sintered carbides are hyper-stoichiometric. The reactions of carbon with UN, PuN and (U,Pu)N has also been studied. Under vacuum, carbon reacts on the nitrides at temperatures as low as 1100 C; nitrogen is replaced by carbon and the final product is a carbonitride. The reaction is: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. The reaction is limited and the carbonitrides have a fixed composition in presence of M{sub 2}C{sub 3} or MC{sub 2}; hence it is impossible to produce pure MC using the reaction. The ternary diagram U-C-N, Pu-C-N and (U,Pu)C-N have been drawn. They show clearly that it is possible to obtain single phase carbonitrides in a wide domain of compositions. (author) [French] On decrit les reactions avec l'azote de UC, PuC,(U,Pu)C,UC{sub 2} et U(C{sub 1-x}O{sub x}), par action directe de l'azote a temperature moderee (de l'ambiante a 450 C). On a etudie l'influence de la contamination par l'azote des poudres de carbures necessaires au frittage sur la nature des produits frittes; on a montre que les carbures frittes obtenus sont hyperstoechiometriques. On a etudie parallelement les reactions du carbone avec UN, PuN et (U,Pu)N. Sous vide le carbone reagit sur les nitrures des 1100 C: le carbone se substitue a l'azote; l'azote libere est elimine et le produit final est un carbonitrure. La reaction s'ecrit: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. La reaction est limitee et les carbonitrures obtenus ont une composition limite fixe en presence des carbures superieurs M{sub 2}C{sub 3} et MC{sub 2}; il est donc impossible d'obtenir MC pur par cette reaction. Les diagrammes

DFT and two-dimensional correlation analysis methods for evaluating the Pu3+–Pu4+ electronic transition of plutonium-doped zircon

International Nuclear Information System (INIS)

Bian, Liang; Dong, Fa-qin; Song, Mian-xin; Dong, Hai-liang; Li, Wei-Min; Duan, Tao; Xu, Jin-bao; Zhang, Xiao-yan

2015-01-01

Highlights: • Effect of Pu f-shell electron on the electronic property of zircon is calculated via DFT and 2D-CA techniques. • Reasons of Pu f-shell electron influencing on electronic properties are systematically discussed. • Phase transitions are found at two point 2.8 mol% and 7.5 mol%. - Abstract: Understanding how plutonium (Pu) doping affects the crystalline zircon structure is very important for risk management. However, so far, there have been only a very limited number of reports of the quantitative simulation of the effects of the Pu charge and concentration on the phase transition. In this study, we used density functional theory (DFT), virtual crystal approximation (VCA), and two-dimensional correlation analysis (2D-CA) techniques to calculate the origins of the structural and electronic transitions of Zr 1−c Pu c SiO 4 over a wide range of Pu doping concentrations (c = 0–10 mol%). The calculations indicated that the low-angular-momentum Pu-f xy -shell electron excites an inner-shell O-2s 2 orbital to create an oxygen defect (V O-s ) below c = 2.8 mol%. This oxygen defect then captures a low-angular-momentum Zr-5p 6 5s 2 electron to form an sp hybrid orbital, which exhibits a stable phase structure. When c > 2.8 mol%, each accumulated V O-p defect captures a high-angular-momentum Zr-4d z electron and two Si-p z electrons to create delocalized Si 4+ → Si 2+ charge disproportionation. Therefore, we suggest that the optimal amount of Pu cannot exceed 7.5 mol% because of the formation of a mixture of ZrO 8 polyhedral and SiO 4 tetrahedral phases with the orientation (10-1). This study offers new perspective on the development of highly stable zircon-based solid solution materials

Disulfide bond effects on protein stability: designed variants of Cucurbita maxima trypsin inhibitor-V.

Science.gov (United States)

Zavodszky, M; Chen, C W; Huang, J K; Zolkiewski, M; Wen, L; Krishnamoorthi, R

2001-01-01

Attempts to increase protein stability by insertion of novel disulfide bonds have not always been successful. According to the two current models, cross-links enhance stability mainly through denatured state effects. We have investigated the effects of removal and addition of disulfide cross-links, protein flexibility in the vicinity of a cross-link, and disulfide loop size on the stability of Cucurbita maxima trypsin inhibitor-V (CMTI-V; 7 kD) by differential scanning calorimetry. CMTI-V offers the advantage of a large, flexible, and solvent-exposed loop not involved in extensive intra-molecular interactions. We have uncovered a negative correlation between retention time in hydrophobic column chromatography, a measure of protein hydrophobicity, and melting temperature (T(m)), an indicator of native state stabilization, for CMTI-V and its variants. In conjunction with the complete set of thermodynamic parameters of denaturation, this has led to the following deductions: (1) In the less stable, disulfide-removed C3S/C48S (Delta Delta G(d)(50 degrees C) = -4 kcal/mole; Delta T(m) = -22 degrees C), the native state is destabilized more than the denatured state; this also applies to the less-stable CMTI-V* (Delta Delta G(d)(50 degrees C) = -3 kcal/mole; Delta T(m) = -11 degrees C), in which the disulfide-containing loop is opened by specific hydrolysis of the Lys(44)-Asp(45) peptide bond; (2) In the less stable, disulfide-inserted E38C/W54C (Delta Delta G(d)(50 degrees C) = -1 kcal/mole; Delta T(m) = +2 degrees C), the denatured state is more stabilized than the native state; and (3) In the more stable, disulfide-engineered V42C/R52C (Delta Delta G(d)(50 degrees C) = +1 kcal/mole; Delta T(m) = +17 degrees C), the native state is more stabilized than the denatured state. These results show that a cross-link stabilizes both native and denatured states, and differential stabilization of the two states causes either loss or gain in protein stability. Removal of hydrogen

Determination of 240Pu/239Pu isotopic ratios in human tissues collected from areas around the Semipalatinsk Nuclear Test Site by sector-field high resolution ICP-MS.

Science.gov (United States)

Yamamoto, M; Oikawa, S; Sakaguchi, A; Tomita, J; Hoshi, M; Apsalikov, K N

2008-09-01

Information on the 240Pu/239Pu isotope ratios in human tissues for people living around the Semipalatinsk Nuclear Test Site (SNTS) was deduced from 9 sets of soft tissues and bones, and 23 other bone samples obtained by autopsy. Plutonium was radiochemically separated and purified, and plutonium isotopes (239Pu and 240Pu) were determined by sector-field high resolution inductively coupled plasma-mass spectrometry. For most of the tissue samples from the former nine subjects, low 240Pu/239Pu isotope ratios were determined: bone, 0.125 +/- 0.018 (0.113-0.145, n = 4); lungs, 0.063 +/- 0.010 (0.051-0.078, n = 5); and liver, 0.148 +/- 0.026 (0.104-0.189, n = 9). Only 239Pu was detected in the kidney samples; the amount of 240Pu was too small to be measured, probably due to the small size of samples analyzed. The mean 240Pu/239Pu isotope ratio for bone samples from the latter 23 subjects was 0.152 +/- 0.034, ranging from 0.088 to 0.207. A significant difference (a two-tailed Student's t test; 95% significant level, alpha = 0.05) between mean 240Pu/239Pu isotope ratios for the tissue samples and for the global fallout value (0.178 +/- 0.014) indicated that weapons-grade plutonium from the atomic bombs has been incorporated into the human tissues, especially lungs, in the residents living around the SNTS. The present 239,240Pu concentrations in bone, lung, and liver samples were, however, not much different from ranges found for human tissues from other countries that were due solely to global fallout during the 1970's-1980's.

Inhaled 239PuO2 in rats with pulmonary emphysema

International Nuclear Information System (INIS)

Lundgren, D.L.; Mauderly, J.L.; Hahn, F.F.

1984-01-01

The modifying effects of a pre-existing lung disease (emphysema) on the deposition, distribution, retention, and effects of inhaled 239 PuO 2 in the rat are being investigated. Preliminary observations indicated that the deposition and retention patterns for 239 Pu particles inhaled by rats with emphysema and control rats were similar, but the distribution of inhaled 239 Pu immediately after exposure was different. Respiratory function measured through one year after exposure to 239 Pu was consistent with emphysema and was not altered by the 239 Pu lung burden. Long-term observations are continuing. 4 references, 2 tables

Measurement of the fission cross-section of $^{240}$Pu and $^{242}$Pu at CERN's n_TOF Facility

CERN Multimedia

Pavlik, A F; Gonzalez romero, E M

The n_TOF Collaboration proposes to continue the fission program, already started in 2002-2004, taking advantage of the newly constructed Work Sector Type A, with the measurement of the two isotopes : $^{240}$ Pu and $^{242}$ Pu. They are both of major importance for reactor physics applications and are included in the Nuclear Energy Agency (NEA) High Priority List [1], in the NEA WPEC Subgroup 26 Report on the accuracy of nuclear data for advanced reactor designe [2] and in the EU 6$^{th}$ Framework Programme IP-EUROTRANS/NUDATRA reports [3]. Based on those requests, the measurement of the fission cross-section of the two Pu isotopes is one of the objectives of the project ANDES of the FP7 EURATOM program [4].

A 244Pu spike reference material CBNM IRM-042A

International Nuclear Information System (INIS)

Verbruggen, A.; Gallet, M.; Hendrickx, F.; Bievre, P. de

1991-01-01

An highly enriched 244 Pu isotopic reference material (CBNM IRM-042a) has been prepared and certified for 244 Pu isotope concentration. The certified value of (2.257 7 ± 0.004 4).10 18 atoms 242 Pu.kg -1 of solution has been established by isotope dilution mass spectrometry. The plutonium isotopic composition has been determined by thermal ionization mass spectrometry and calibration of these measurements by means of synthetic 242 Pu/ 239 Pu mixtures. The isotopic reference material is supplied in a sealed glass ampoule containing approximately 10 g of a 5M nitric acid solution at an approximate concentration of 1 μg Pu per g solution. This isotopic reference material is part of a systematic CBNM programme to supply spike isotopic reference materials of various isotopes at different concentrations

Sequential determination of {sup 239,240}Pu, {sup 238} Pu, {sup 241} Am and {sup 90}Sr in radioactive wastes using SPE sorbents Analig Pu02, AnaLig Sr01 and TRU Resin; Sekvencne stanovenie {sup 239,240}Pu, {sup 238} Pu, {sup 241} Am a {sup 90}Sr v radioaktivnych odpadoch pouzitim SPE sorbentov Analig Pu02, AnaLig Sr01 a TRU Resin

Energy Technology Data Exchange (ETDEWEB)

Durkot, E; Dulanska, S [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra jadrovej chemie, 84215 Bratislava (Slovakia)

2012-04-25

A simple and rapid method of the sequential determination of radionuclides {sup 239,240}Pu, {sup 238} Pu, {sup 241} Am and {sup 90}Sr in radioactive sludge from the NPP Bohunice A1 with high radiochemical yields and efficient removal of interfering components from a matrix was developed. Separation method combines SPE sorbents Analig Pu02, AnaLig Sr01 made by IBC Advanced Technologies and TRU Resin (Eichrom Technologies) placed in tandem. Advantage of a single-stage column located on the vacuum box with a rapid flow is an effective pre-concentration and separation of radionuclides and minimization of sample separation time. (authors)

Impurity-related nonlinear optical properties in delta-doped quantum rings: Electric field effects

Energy Technology Data Exchange (ETDEWEB)

Restrepo, R.L., E-mail: rrestre@gmail.com [Escuela de Ingeniería de Antioquia-EIA, Medellín (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Morales, A.L. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Martínez-Orozco, J.C. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, CP 98060, Zacatecas (Mexico); Baghramyan, H.M.; Barseghyan, M.G. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Mora-Ramos, M.E. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

2014-11-15

Using a variational procedure within the effective mass approximation, we have calculated the donor impurity binding energy for the ground (1s-like) and the excited (2p{sub z}-like) states as well as the impurity-related nonlinear optical absorption and relative changes in the refraction index in a GaAs single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is an approximate model analytically described using a Lorentzian function with two parameters. Additionally we consider the application of an electric field along the z-direction. It is found that the changes in the geometry of the quantum ring, the change in the 2D impurity density of the delta-like doping, and different values of the electric field lead to a shifting of the resonant peaks of the optical responses spectrum.

Impurity-related nonlinear optical properties in delta-doped quantum rings: Electric field effects

International Nuclear Information System (INIS)

Restrepo, R.L.; Morales, A.L.; Martínez-Orozco, J.C.; Baghramyan, H.M.; Barseghyan, M.G.; Mora-Ramos, M.E.; Duque, C.A.

2014-01-01

Using a variational procedure within the effective mass approximation, we have calculated the donor impurity binding energy for the ground (1s-like) and the excited (2p z -like) states as well as the impurity-related nonlinear optical absorption and relative changes in the refraction index in a GaAs single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is an approximate model analytically described using a Lorentzian function with two parameters. Additionally we consider the application of an electric field along the z-direction. It is found that the changes in the geometry of the quantum ring, the change in the 2D impurity density of the delta-like doping, and different values of the electric field lead to a shifting of the resonant peaks of the optical responses spectrum

The impact of Pu speciation on distribution coefficients in Mayak soil.

Science.gov (United States)

Skipperud, L; Oughton, D; Salbu, B

2000-08-10

To assess the long-term consequences when radionuclides are released into the environment, information on the source term, transport and transformation processes, interaction with soils (KD) and biological uptake (CF) is needed. Among the artificial radionuclides released to the environment by nuclear activities, the transuranium elements are a major concern, due to very long half-lives and their accumulation in bone as well as high radiotoxicity. Plutonium has been produced in greater quantity than other transuranic elements, however, environmental assessments are complicated by the complex environmental behaviour. Physico-chemical forms of Pu will determine the interactions with soils and, thus, the degree to which soils can act as a sink or a potential diffuse source of contaminants. In the present work, dynamic tracer experiments have been performed where different Pu-species are added to a 'Mayak soil-rainwater system' to obtain information on KD values. After a defined contact time, the samples where then sequentially extracted and results are used in a dynamic box model to estimate interaction and fixation rates. The interaction of all Pu-species with soils seems to be rapid and follows a two-step reaction. Up to contact times of a few weeks, the KD for Pu(III,IV) (730 +/- 240 l/kg) is approximately one order of magnitude higher than for Pu(V,VI) (90 +/- 20 l/kg) and Pu(III,IV)-organic (40-60 l/kg). After 3 months contact time, the KD in only the two organic-bound Pu-species were significantly lower. This shows that the initial association with the soil is dependent on the Pu-species in the rainwater. After only 1 h of contact, between 33 and 40% of the plutonium was strongly bound to the soil components, i.e. only extractable with strong HNO3. The extraction of soil-bound Pu followed a similar pattern for all the original species, suggesting that the next step of Pu interaction mechanism with soil was rather independent of the original species. For both the

Fabrication and improved photoelectrochemical properties of a transferred GaN-based thin film with InGaN/GaN layers.

Science.gov (United States)

Cao, Dezhong; Xiao, Hongdi; Gao, Qingxue; Yang, Xiaokun; Luan, Caina; Mao, Hongzhi; Liu, Jianqiang; Liu, Xiangdong

2017-08-17

Herein, a lift-off mesoporous GaN-based thin film, which consisted of a strong phase-separated InGaN/GaN layer and an n-GaN layer, was fabricated via an electrochemical etching method in a hydrofluoric acid (HF) solution for the first time and then transferred onto quartz or n-Si substrates, acting as photoanodes during photoelectrochemical (PEC) water splitting in a 1 M NaCl aqueous solution. Compared to the as-grown GaN-based film, the transferred GaN-based thin films possess higher and blue-shifted light emission, presumably resulting from an increase in the surface area and stress relaxation in the InGaN/GaN layer embedded on the mesoporous n-GaN. The properties such as (i) high photoconversion efficiency, (ii) low turn-on voltage (-0.79 V versus Ag/AgCl), and (iii) outstanding stability enable the transferred films to have excellent PEC water splitting ability. Furthermore, as compared to the film transferred onto the quartz substrate, the film transferred onto the n-Si substrate exhibits higher photoconversion efficiency (2.99% at -0.10 V) due to holes (h + ) in the mesoporous n-GaN layer that originate from the n-Si substrate.

Radiative capture on $^{242}$Pu for MOX fuel reactors

CERN Multimedia

The use of MOX fuel (mixed-oxide fuel made of UO$_{2}$ and PuO$_{2}$) in nuclear reactors allows substituting a large fraction of the enriched Uranium by Plutonium reprocessed from spent fuel. Indeed around 66% of the plutonium from spent fuel is made of $^{239}$Pu and $^{241}$Pu, which are fissile in thermal reactors. A typical reactor of this type uses a fuel with 7% reprocessed Pu and 93% depleted U, thus profiting from both the spent fuel and the remaining $^{238}$U following the $^{235}$U enrichment. With the use of such new fuel compositions rich in Pu the better knowledge of the capture and fission cross sections of the Pu isotopes becomes very important. This is clearly stated in the recent OECD NEA’s “High Priority Request List” and in the WPEC-26 “Uncertainty and target accuracy assessment for innovative systems using recent covariance data evaluations” report. In particular, a new series of cross section evaluations have been recently carried out jointly by the European (JEFF) and United ...

239,240Pu distribution in the Japanese

International Nuclear Information System (INIS)

Hisamatsu, Shun-ichi

1996-01-01

Distribution of 239,240 Pu and 241 Am in the Japanese were reviewed, and compared with those estimated with ICRP metabolic models. Inhalation and ingestion amount of these nuclides were calculated from simple models, and used as input to the ICRP metabolic models. ICRP-30 model or the combination of ICRP-66 lung model and ICRP-67 metabolic model were used for the calculation. The estimated 239,240 Pu concentrations in lung, liver, skeleton, kidney and muscle by using of the combination of ICRP-66 and 67 models agreed well with the measured data in most cases. The contribution of ingestion intake to body burden of 239,240 Pu was estimated to be 12% with 5 x 10 -4 as f 1 value. The combination of ICRP-66 and 67 model could described fairly well the organ burden of 241 Am measured in Akita and Niigata district. The 241 Am grown from 241 Pu in the human body was calculated to contribute 90% of the burden. (author)

Mechanical properties of 238PuO2

International Nuclear Information System (INIS)

Petrovic, J.J.; Hecker, S.S.; Land, C.C.; Rohr, D.L.

1977-04-01

The mechanical properties of 238 PuO 2 have been examined in the Los Alamos Scientific Laboratory mechanical test facility built to handle α-radioactive materials. Compression tests were conducted as a function of temperature, strain rate, grain size, density, and storage time. At temperatures less than or equal to 1400 0 C, test specimens of 238 PuO 2 exhibit pseudobrittle behavior due to internal cracks. Plastic deformation is ''localized'' at the crack tips. Generalized plastic deformation is observed at 1500 0 C. Ultimate stress values decrease markedly with increasing temperature and decreasing strain rate, and decrease less with decreasing density, increasing storage time, and increasing grain size. Room temperature fracture is transgranular, whereas intergranular fracture predominates at elevated temperatures. Crack-free specimens of 239 PuO 2 exhibit extensive plastic deformation at 1000 0 C and above. The relationship of these test results to the impact properties of 238 PuO 2 fuel in radioisotope thermoelectric generators is discussed

PuMA: the Porous Microstructure Analysis software

Science.gov (United States)

Ferguson, Joseph C.; Panerai, Francesco; Borner, Arnaud; Mansour, Nagi N.

2018-01-01

The Porous Microstructure Analysis (PuMA) software has been developed in order to compute effective material properties and perform material response simulations on digitized microstructures of porous media. PuMA is able to import digital three-dimensional images obtained from X-ray microtomography or to generate artificial microstructures. PuMA also provides a module for interactive 3D visualizations. Version 2.1 includes modules to compute porosity, volume fractions, and surface area. Two finite difference Laplace solvers have been implemented to compute the continuum tortuosity factor, effective thermal conductivity, and effective electrical conductivity. A random method has been developed to compute tortuosity factors from the continuum to rarefied regimes. Representative elementary volume analysis can be performed on each property. The software also includes a time-dependent, particle-based model for the oxidation of fibrous materials. PuMA was developed for Linux operating systems and is available as a NASA software under a US & Foreign release.

Electrocatalytic performance of Pu(IV)/Pu(III) redox reaction at graphene modified glassy carbon electrode

International Nuclear Information System (INIS)

Gupta, Ruma; Gamare, J.S.; Kamat, J.V.; Aggarwal, S.K.

2014-01-01

In this paper we explore the analytical perspectives of graphene modified electrode utilising commercially available graphene, which is well characterised, completely free from surfactants and has not been purposely oxidised or treated. We compare and critically contrast the electro-analytical performance of graphene modified glassy carbon electrodes (Gr/GC) with that of unmodified GC electrode towards Pu(IV)/Pu(III) redox reaction, monitoring of which has considerable importance in a plethora of areas where electrochemistry is conveniently and beneficially utilised for determination of nuclear fuels

Preliminary safety evaluation for the plutonium stabilization and packaging system

International Nuclear Information System (INIS)

Shapley, J.E.

1997-01-01

This Preliminary Safety Evaluation (PSE) describes and analyzes the installation and operation of the Plutonium Stabilization and Packaging System (SPS) at the Plutonium Finishing Plant (PFP). The SPS is a combination of components required to expedite the safe and timely storage of Plutonium (Pu) oxide. The SPS program will receive site Pu packages, process the Pu for storage, package the Pu into metallic containers, and safely store the containers in a specially modified storage vault. The location of the SPS will be in the 2736- ZB building and the storage vaults will be in the 2736-Z building of the PFP, as shown in Figure 1-1. The SPS will produce storage canisters that are larger than those currently used for Pu storage at the PFP. Therefore, the existing storage areas within the PFP secure vaults will require modification. Other modifications will be performed on the 2736-ZB building complex to facilitate the installation and operation of the SPS

Chemical thermodynamic representation of (U, Pu, Am)O2-x

International Nuclear Information System (INIS)

Osaka, Masahiko; Namekawa, Takashi; Kurosaki, Ken; Yamanaka, Shinsuke

2005-01-01

The oxygen potential isotherms of (U, Pu, Am)O 2-x were represented by a chemical thermodynamic model proposed by Lindemer et al. It was assumed in the present model that (U, Pu, Am)O 2-x consisted of the chemical species [UO 2 ], [PuO 2 ], [Pu 4/3 O 2 ], [AmO 2 ] and [Am 5/4 O 2 ] in a pseudo-quaternary system by treating the reduction rates of Pu and Am as identical; furthermore an interaction between [Am 5/4 O 2 ] and [UO 2 ] was introduced. The agreement between analytical and experimental isotherms was good, but the analytical values slightly overestimated the experimental values especially in the case of lower Am content. Adding an interaction between [Am 5/4 O 2 ] and [PuO 2 ] to the model resulted in a better representation

Determination of the neutron-induced fission cross section of {sup 242}Pu; Bestimmung des neutroneninduzierten Spaltquerschnitts von {sup 242}Pu

Energy Technology Data Exchange (ETDEWEB)

Koegler, Toni Joerg

2016-04-26

Neutron induced fission cross sections of actinides like the Pu-isotopes are of relevance for the development of nuclear transmutation technologies. For {sup 242}Pu, current uncertainties are of around 21%. Sensitivity studies show that the total uncertainty has to be reduced to below 5% to allow for reliable neutron physics simulations. This challenging task was performed at the neutron time-of-flight facility of the new German National Center for High Power Radiation Sources at HZDR, Dresden. Within the TRAKULA project, thin, large and homogeneous deposits of {sup 235}U and {sup 242}Pu have been produced successfully. Using two consecutively placed fission chambers allowed the determination of the neutron induced fission cross section of {sup 242}Pu relative to {sup 235}U. The areal density of the Plutonium targets was calculated using the measured spontaneous fission rate. Experimental results of the fast neutron induced fission of {sup 242}Pu acquired at nELBE will be presented and compared to recent experiments and evaluated data. Corrections addressing the neutron scattering are discussed by using results of different neutron transport simulations (Geant 4, MCNP 6 and FLUKA).

Structural stability of (Pu{sub 1-x}Am{sub x})O{sub 2} (x=0.2;0.5;0.8) obtained by oxalate co-conversion

Energy Technology Data Exchange (ETDEWEB)

Jankowiak, A.; Donnet, L. [Commissariat a l' Energie Atomique, CEA/DEN/VRH/DTEC/SDTC/LEMA, 30207 Bagnols-sur-Ceze cedex (France); Maillard, C. [Commissariat a l' Energie Atomique, CEA/DEN/VRH/DRCP/SE2A/LEHA, 30207 Bagnols-sur-Ceze cedex (France)

2008-07-01

The EUROTRANS project investigates the transmutation of transuranium elements in dedicated reactors (ADS, FR). The study includes various subject areas: neutronics, physical properties, coolant type (sodium, lead, bismuth, helium), etc, and experimental work concerning the fabrication of minor actinide compounds for thermo-physical properties determination. For this program, the CEA was responsible for synthesizing three Pu{sub 1-x}Am{sub x}O{sub 2} compounds with various Am and Pu content (x = 0.2, 0.5, 0.8). The selected synthesis route for the mixed Am and Pu oxide powder consists in actinides oxalates co-conversion. The purpose of the study was to determine by XRD the crystal structure and the lattice parameters change as a function of the time for each co-converted mixed oxides. After one year of experiment, although the lattice parameters significantly expanded, the compounds remained monophasic. The observations showed that the initial expansion rate and the a{sub max} stage value vary according to the Pu and Am content. (authors)

Vertical distribution of 239+240Pu-concentration and 240Pu/239Pu isotope ratio in sediment cores. Implications for the sources of plutonium in the Japan Sea

International Nuclear Information System (INIS)

Yamada, Masatoshi; Jian, Zheng

2005-01-01

The main sources in the environmental plutonium is due to nuclear explosions held during 1945 - 1980. The global fallout of plutonium is estimated to amount to 10.9 PBq, of which 6.6 PBq entering into the ocean. The Japan Sea is reported to be concentrated in plutonium in excess according to previous measurements. The present report aims to clarify the origin and transport path of plutonium in Japan Sea by measuring 240 Pu/ 239 Pu ratio in sedimenta cores with ICP-MS (Inductively Coupled Plasma Mass Spectrometry) which depends on the types of the nuclear reactor, nuclear fuels, reacting time, or the types of nuclear weapons concerned. As an example the 240 Pu/ 239 Pu ratio from the nuclear explosions in early 1960's is known to be 0.18, while that of 0.34-0.36 Bikini experiments in the Marshall Islands in early 1950's. After a detailed examination, the present authors propose that the plutonium from the explosion sites around the Marshall Islands was carried with an oceanic current to be deposited in the bed of the East-China Sea, from which a part of the plutonium was transported with the Black Stream to enter Japan Sea. (S. Ohno)

Study of phase equilibrium of Pu2O3-PuO2 system by the first-principles calculation and CALPHAD approach

International Nuclear Information System (INIS)

Minamoto, Satoshi; Kato, Masato; Konashi, Kenji

2010-01-01

A combination of a first-principles calculation, lattice dynamics and CALPHAD (CALculation of PHAse Diagrams) modeling is proven as a powerful tool so as to evaluate the Gibbs free energy and a phase equilibrium between compounds including large amount of vacancies. In this work, non-stoichiometric PuO 2-x (dioxide) and Pu 2 O 3 (sesquioxide) has been studied. An electron cohesive energy was evaluated from a first-principles calculations to estimate total energy of the compounds and a vacancy formation energy, and the theory of statistical mechanics was applied to evaluate enthalpy/entropy change due to oxygen vacancies for the non-stoichiometry of the PuO 2 (i.e. PuO 2-x ). Then a vacancy-vacancy interaction energy was determined by fitting to the experimental data of a quantity of non-stoichiometry of the PuO 2 compounds as a function of oxygen potentials at large deviation from stoichiometry. The resulting Gibbs free energy yields phase boundary between the phases with good agreement with to the experimental data.

Historical changes in ²³⁹Pu and ²⁴⁰Pu sources in sedimentary records in the East China Sea: Implications for provenance and transportation

DEFF Research Database (Denmark)

Wang, Jinlong; Baskaran, Mark; Hou, Xiaolin

2017-01-01

from 0.158 to 0.297 and were mostly higher than the mean global fallout value of 0.18. The 239,240Pu inventories in the ECS varied widely, from 2 to 807 Bqm−2, with the highest values commonly found in the coastal areas. In the Yangtze Estuary, the mean 239+240Pu activity concentration is close...... to the estimated value of the suspended material from the Yangtze River catchment (0.18 Bqkg−1), and the 240Pu/239Pu atom ratio was found to be ∼0.18, which indicates that the Yangtze River input is the dominant source of Pu for this area. The total annual Yangtze River input of 239+240Pu was estimated to be 2...

The situation in the Niger Delta; La situation dans le delta du Niger

Energy Technology Data Exchange (ETDEWEB)

Vitalis, E

2007-07-15

An energy issue for the United States and a political challenge for Europe, Nigeria is experiencing growing instability and is on the verge of civil war; the ecosystem and the population of the Niger Delta are the main victims. The State, corrupt, is powerless to contain the rising violence and redistribute the proceeds of oil sales. It is high time for oil-consuming countries, starting with the United States, to concern themselves with stabilizing the region. Europe must contribute to the lasting development of this country. (author)

Determination of isotope fractionation effect using a double spike (242Pu+240Pu) during the mass spectrometric analysis of plutonium

International Nuclear Information System (INIS)

Chitambar, S.A.; Parab, A.R.; Khodade, P.S.; Jain, H.C.

1986-01-01

Isotope fractionation effect during the mass spectrometric analysis of plutonium has been investigated using a double spike ( 242 Pu+ 240 Pu) and the determination of concentration of plutonium in dissolver solution of irradiated fuel is reported. (author). 6 refs., 2 tables

Construction and maintenance of the Ganges-Brahmaputra-Meghna delta: linking process, morphology, and stratigraphy.

Science.gov (United States)

Wilson, Carol A; Goodbred, Steven L

2015-01-01

We present a review of the processes, morphology, and stratigraphy of the Ganges-Brahmaputra-Meghna delta (GBMD), including insights gained from detailed elevation data. The review shows that the GBMD is best characterized as a composite system, with different regions having morphologic and stratigraphic attributes of an upland fluvial fan delta; a lowland, backwater-reach delta; a downdrift tidal delta plain; and an offshore subaqueous-delta clinoform. These distinct areas of upland and lowland fluvial reaches and tidal dominance vary in time and space, and we distinguish late-Holocene phases of delta construction, maintenance, and decline similar to delta-lobe cycling in other systems. The overall stability of the GBMD landform, relative to many deltas, reflects the efficient, widespread dispersal of sediment by the large monsoon discharge and high-energy tides that affect this region. However, we do identify portions of the delta that are in decline and losing elevation relative to sea level owing to insufficient sediment delivery. These areas, some of which are well inland of the coast, represent those most at risk to the continued effect of sea-level rise.

III-Nitrides growth and AlGaN/GaN heterostructures on ferroelectric materials

International Nuclear Information System (INIS)

Lee, Kyoung-Keun; Namkoong, Gon; Madison, Shannon M.; Ralph, Stephen E.; Doolittle, W. Alan; Losurdo, Maria; Bruno, Giovanni; Cho, Hyung Koun

2007-01-01

The growth of III-nitrides on the ferroelectric materials lithium niobate (LN) and lithium tantalate (LT) via molecular beam epitaxy (MBE) using rf plasma source has been investigated. We have found that gallium nitride (GaN) epitaxial layers have a crystalline relationship with lithium niobate (tantalate) as follows: (0 0 0 1) GaN || (0 0 0 1) LN (LT) with [10-10] GaN || [11-20] LN (LT). The surface stability of LN and LT substrates has been monitored by in situ spectroscopic ellipsometry in the vacuum chamber. Three different temperature zones have been discerned; surface degas and loss of OH group (100-350 deg. C); surface segregation/accumulation of Li and O-species (400-700 deg. C); surface evaporation of O-species and Li desorption (over 750 deg. C). However, LT shows only surface degassing in the range of 100-800 deg. C. Therefore, congruent LN substrates were chemically unstable at the growth temperature of 550-650 deg. C, and therefore developed an additional phase of Li-deficient lithium niobate (LiNb 3 O 8 ) along with lithium niobate (LiNbO 3 ), confirmed by X-ray diffraction. On the other hand, LT showed better chemical stability at these temperatures, with no additional phase development. The structural quality of GaN epitaxial layers has shown slight improvement on LT substrates over LN substrates, according to X-ray diffraction. Herein, we demonstrate AlGaN/GaN heterostructure devices on ferroelectric materials that will allow future development of multifunctional electrical and optical applications

III-Nitrides growth and AlGaN/GaN heterostructures on ferroelectric materials

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyoung-Keun [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States); Namkoong, Gon [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, VA 23529 (United States); Madison, Shannon M. [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States); Ralph, Stephen E. [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States); Doolittle, W. Alan [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States)]. E-mail: alan.doolittle@ece.gatech.edu; Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, Department of Chemistry, University of Bari, via Orabona, 4 70126 Bari (Italy); Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, Department of Chemistry, University of Bari, via Orabona, 4 70126 Bari (Italy); Cho, Hyung Koun [Department of Materials Science and Engineering, Sung Kyun Kwan University, Suwon 440-746 (Korea, Republic of)

2007-06-15

The growth of III-nitrides on the ferroelectric materials lithium niobate (LN) and lithium tantalate (LT) via molecular beam epitaxy (MBE) using rf plasma source has been investigated. We have found that gallium nitride (GaN) epitaxial layers have a crystalline relationship with lithium niobate (tantalate) as follows: (0 0 0 1) GaN || (0 0 0 1) LN (LT) with [10-10] GaN || [11-20] LN (LT). The surface stability of LN and LT substrates has been monitored by in situ spectroscopic ellipsometry in the vacuum chamber. Three different temperature zones have been discerned; surface degas and loss of OH group (100-350 deg. C); surface segregation/accumulation of Li and O-species (400-700 deg. C); surface evaporation of O-species and Li desorption (over 750 deg. C). However, LT shows only surface degassing in the range of 100-800 deg. C. Therefore, congruent LN substrates were chemically unstable at the growth temperature of 550-650 deg. C, and therefore developed an additional phase of Li-deficient lithium niobate (LiNb{sub 3}O{sub 8}) along with lithium niobate (LiNbO{sub 3}), confirmed by X-ray diffraction. On the other hand, LT showed better chemical stability at these temperatures, with no additional phase development. The structural quality of GaN epitaxial layers has shown slight improvement on LT substrates over LN substrates, according to X-ray diffraction. Herein, we demonstrate AlGaN/GaN heterostructure devices on ferroelectric materials that will allow future development of multifunctional electrical and optical applications.

Effect of Pu-rich agglomerate in MOX fuel on a lattice calculation

International Nuclear Information System (INIS)

Kawashima, Katsuyuki; Yamamoto, Toru; Namekawa, Masakazu

2007-01-01

The effect of Pu-rich agglomerates in U-Pu mixed oxide (MOX) fuel on a lattice calculation has been demonstrated. The Pu-rich agglomerate parameters are defined based on the measurement data of MIMAS-MOX and the focus is on the highly enriched MOX fuel in accordance with increased burnup resulting in a higher volume fraction of the Pu-rich agglomerates. The lattice calculations with a heterogeneous fuel model and a homogeneous fuel model are performed simulating the PWR 17x17 fuel assembly. The heterogeneous model individually treats the Pu-rich agglomerate and U-Pu matrix, whereas the homogeneous model homogenizes the compositions within the fuel pellet. A continuous-energy Monte Carlo burnup code, MVP-BURN, is used for burnup calculations up to 70 GWd/t. A statistical geometry model is applied in modeling a large number of Pu-rich agglomerates assuming that they are distributed randomly within the MOX fuel pellet. The calculated nuclear characteristics include k-inf, Pu isotopic compositions, power density and burnup of the Pu-rich agglomerates, as well as the pellet-averaged Pu compositions as a function of burnup. It is shown that the effect of Pu-rich agglomerates on the lattice calculation is negligibly small. (author)

The unrivalled expertise for Pu recycling

International Nuclear Information System (INIS)

Fournier, W.; Pouilloux, M.

1997-01-01

Relying on the outstanding performances of the reprocessing facilities and the growing fabrication facilities, the in-reactor Pu recycling program in France and in other European countries is steadily implemented and has reached full-scale industrial operation. The RCR strategy -Reprocessing, Conditioning and Recycling- developed by COGEMA is now a well proven industrial reality. In 1997, plutonium recycling through MOX fuel is a mature industry, with successful operational experience and large-scale fabrication plants. In this field, COGEMA is the main actor, on operating simultaneously three complete multidesign fuel production plants: MELOX plant (in Marcoule), CADARACHE plant and DESSEL plant (in Belgium). Present MOX production capacity available to COGEMA fits 175 tHM per year and will be extended to reach about 325 tHM in the year 2000, that will represent 75% of the total MOX fabrication capacity in Europe. The industrial mastery and the high production level in MOX production assured by high technology processes confers COGEMA an unrivalled expertise for Pu recycling. This allows COGEMA to be a major actor in Pu-based fuels in the coming second nuclear era with advanced fuel cycles. The paper depicts the steps of the progressive advance of COGEMA to reach the Pu recycling expertise. (author)

Determination of radionuclides {sup 90}Sr, {sup 239,240} Pu, {sup 238}Pu and {sup 241}Am in soil using methods of extraction chromatography and coprecipitation; Stanovenie radionuklidov {sup 90}Sr, {sup 239,240}Pu, : 2{sup 38}Pu a {sup 241}Am v pode vyuzivajuce metody extrakcnej chromatografie a spoluzrazania

Energy Technology Data Exchange (ETDEWEB)

Gardonova, V.; Dulanska, S.; Bilohuscin, J. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra jadrovej chemie, 84215 Bratislava (Slovakia)

2013-04-16

Ecosystems, which include soil and sediments, contain not only natural radionuclides but also radionuclides from deposits, mainly {sup 137}Cs, {sup 90}Sr and {alpha}-emitting radionuclides such as {sup 239,240}Pu, {sup 238}Pu and {sup 241}Am, that originate from global fallout and nuclear facilities leaks worldwide. The goal of the work was optimization of separation and determination of {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu and {sup 241}Am in soil from Slovak Republic. The newest methods were applied for separation of selected radionuclides based on coprecipitation with oxalic salts and extraction chromatography using selective commercial sorbents. (authors)

Chemical properties of the predicted 32-electron systems PuSn{sub 12} and PuPb{sub 12}

Energy Technology Data Exchange (ETDEWEB)

Dognon, J.P. [CEA Saclay, UMR 3299 CEA/CNRS SIS2M, laboratoire de chimie de coordination des elements f, 91 - Gif-sur-Yvette (France); Clavaguera, C. [Laboratoire des mecanismes reactionnels, departement de chimie, Ecole polytechnique, CNRS, 91 - Palaiseau (France); Pyykko, P. [Department of Chemistry, University of Helsinki (Finland)

2010-06-15

The electronic structures, as well as spectroscopic and thermodynamic properties of the title PuM{sub 12} clusters, are considered at the density functional theory level. In both cases, a Pu{sup 2+} ion is encapsulated in an icosahedral, stanna- or plumbaspherene M{sub 12}{sup 2-} cage. As suggested before for M=Pb, both systems are reported to follow a 32-electron principle for the central atom. (authors)

Study of phase equilibria in function of temperature in UO2-PuO2-Pu2O3 system for nuclear ceramics with high plutonium contents

International Nuclear Information System (INIS)

Truphemus, Thibaut

2013-01-01

In the UO 2 -PuO 2 -Pu 2 O 3 section, a monophasic (U 1-y ,Pu y )O 2-x domain is stable for y≤0,20 at 25 C and up to solid-liquid equilibrium. At higher Pu content, phase equilibria are more unclear with a phase separation process. The main objective of this work consisted in upgrading the representation of this system for 0,15≤y≤0,65 and 25≤T(C)≤1500. At 25 C, a miscibility gap composed by two different (U 1-y ,Pu y )O 2-x phases has been observed for y≤0,45, with one very closed to stoichiometric state (Oxygen/Metal=2) and one other very reduced. For the first time, a triphasic domain has been characterized at higher Pu contents, with two (U 1-y ,Pu y )O 2-x phases near y=0,45 and one (U 1-y ,Pu y ) 2 O 3 phase with a low U content inside. Concerning the study in function of temperature, we have demonstrated that phase separation temperature increase when Pu content grows. Several representations have been established. At 200 C, the representation is closed to that at 25 C. At 400 C, the phase separation have been specified at a lower Pu content than that of literature: y=0,35. At 600 C, our results have clarified the section, until then very unclear, with a phase separation appearing at y=0,60.The microstructural analysis has clearly demonstrated the significant impact of the phase separation on the material. Indeed many cracks have been observed in our samples, and quantity of these defects increases when Pu content grows. (author) [fr

Interception and retention of 238Pu deposition by orange trees

International Nuclear Information System (INIS)

Pinder, J.E. III; Adriano, D.C.; Ciravolo, T.G.; Doswell, A.C.; Yehling, D.M.

1987-01-01

Radioisotope thermoelectric generators (RTG) transform the heat produced during the alpha decay of 238 Pu into electrical energy for use by deep-space probes, such as the Voyager spacecraft, which have returned images and other data from Jupiter, Saturn and Uranus. Future missions involving RTGs may be launched aboard the space shuttle, and there is a remote possibility that an explosion of liquid-hydrogen and liquid-oxygen fuel could rupture the RTGs and disperse 238 Pu into the atmosphere over central Florida. Research was performed to determine the potential transport to man of atmospherically dispersed Pu via contaminated orange fruits. The results indicate that the major contamination of oranges would result from the interception and retention of 238 Pu deposition by fruits. The resulting surface contamination could enter human food chains through transfer to internal tissues during peeling or in the reconstituted juices and flavorings made from orange skins. The interception of 238 Pu deposition by fruits is especially important because the results indicate no measurable loss of Pu from fruit surfaces through time or with washing. Approximately 1% of the 238 Pu deposited onto an orange grove would be harvested in the year following deposition

Chronic cigarette smoke exposure increases the pulmonary retention and radiation dose of 239Pu inhaled as 239PuO2 by F344 rats

International Nuclear Information System (INIS)

Finch, G.L.; Lundgren, D.L.; Barr, E.B.; Chen, B.T.; Griffith, W.C.; Hobbs, C.H.; Hoover, M.D.; Nikula, K.J.; Mauderly, J.L.

1998-01-01

As a portion of a study to examine how chronic cigarette smoke exposure might alter the risk of lung tumors from inhaled 239 PuO 2 in rats, the effects of smoke exposure on alpha-particle lung dosimetry over the life-span of exposed rats were determined. Male and female rats were exposed to inhaled 239 PuO 2 alone or in combination with cigarette smoke. Animals exposed to filtered air along served as controls for the smoke exposure. Whole-body exposure to mainstream smoke diluted to concentrations of either 100 or 250 mg total particulate matter m -3 began at 6 wk of age and continued for 6 h d -1 , 5 d wk -1 , for 30 mo. A single, pernasal, acute exposure to 239 PuO 2 was given to all rats at 12 wk of age. Exposure to cigarette smoke caused decreased body weight gains in a concentration dependent manner. Lung-to-body weight ratios were increased in smoke-exposed rats. Rats exposed to cigarette smoke before the 239 PuO 2 exposure deposited less 239 Pu in the lung than did controls. Except for male rats exposed to LCS, exposure to smoke retarded the clearance of 239 Pu from the lung compared to control rats through study termination at 870 d after 239 PuO 2 exposure. Radiation doses to lungs were calculated by sex and by exposure group for rats on study for at least 360 d using modeled body weight changes, lung-to-body weight ratios, and standard dosimetric calculations. For both sexes, estimated lifetime radiation doses from the time of 239 PuO 2 exposure to death were 3.8 Gy, 4.4 Gy, or 6.7 Gy for the control, LCS, or HCS exposure groups, respectively. Assuming an approximately linear dose-response relationship between radiation dose and lung neoplasm incidence, approximate increases of 20% or 80% in tumor incidence over controls would be expected in rats exposed to 239 PuO 2 and LCS or 239 PuO 2 and HCS, respectively

Contribution to the study of U-Ti and U-Pu-Ti carbides

International Nuclear Information System (INIS)

Milet, C.A.

1968-01-01

After having discussed the reasons to use (U,Pu) carbides as fast reactor fuel, we examine the influence of the addition of titanium to these carbides. A preliminary study has been done on the system of U-C-Ti and some properties have been measured such as: density, thermal expansion, electrical resistivity, atmospheric corrosion and compatibility with stainless steel. The systems U-Pu-C-Ti (Pu/U + Pu equal to 15 per cent) and U-C-Ti have been found to be very similar. There exists a two phases region (U,Pu)C + TiC, an eutectic between (U,Pu)C and TiC for approximately 15 at %. The solubilities of U + Pu in TiC and of Ti in (U,Pu)C is less than 1 % at. The addition of titanium does not markedly change thermal expansion coefficients of (U,Pu)C. However the resistance to atmospheric corrosion and compatibility with stainless steel is improved. Thermal conductivity, calculated from electrical resistivity, has increased. On the other side, the density of fissile material is lowered. The combination of (U,Pu)C + TiC seems to be the most promising alloy for application as nuclear fuel. (author) [fr

238Pu fuel form processes. Final report, January-September 1983

International Nuclear Information System (INIS)

Mosley, W.C.; Taylor, D.H.

1983-01-01

Progress is reported on the following: analytical studies of weld-quench cracking in DOP-26 iridium alloy, iridium/ 238 PuO 2 compatibility test, surface area measurements of 238 PuO 2 using the Blaine air permeability apparatus, and helium release from 238 PuO 2

Fabrication of an integrated {Delta}E-E-silicon detector by wafer bonding using cobalt disilicide

Energy Technology Data Exchange (ETDEWEB)

Thungstroem, G. [Mid-Sweden Univ., Sundsvall (Sweden). Dept. of Inf. Technol.]|[Royal Institute of Technology, Department of Electronics, Electrum 229, S-164 40 Kista (Sweden); Veldhuizen, E.J. van [Uppsala University, Department of Radiation Science, Box 535, S-751 21 Uppsala (Sweden); Westerberg, L. [Uppsala University, The Svedberg Laboratory, Box 533, S-751 21 Uppsala (Sweden); Norlin, L.-O. [Royal Institute of Technology, Department of Physics, Frescativaegen 24, S-104 05 Stockholm (Sweden); Petersson, C.S. [Royal Institute of Technology, Department of Electronics, Electrum 229, S-164 40 Kista (Sweden)

1997-06-01

The problem concerning mechanical stability of thin self-supporting {Delta}E detector in a {Delta}E-E semiconductor detector telescope, has been solved by integrating both detectors into one unit. We show here a low-cost method to integrate the detectors by wafer bonding using cobalt disilicide. The {Delta}E-detector has a thickness of 6.5 {mu}m and the E detector 290 {mu}m with an area of 24.8 mm{sup 2}. The system was characterized with secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), electrical measurement, particle measurement and two-dimensional electrical simulation. (orig.).

Measurement of the ${240}$Pu(n,f) reaction cross-section

CERN Multimedia

Following proposal CERN-INTC-2010-042 / INTC-P-280 (“Measurement of the fission cross-section of $^{240}$Pu and $^{242}$Pu at CERN’s n_TOF Facility”), the parallel measurement of the $^{240}$Pu(n,f) and $^{242}$Pu(n,f) reaction cross-sections was carried out at n_TOF EAR-1. While the $^{242}$Pu measurement was successful, unexpected sample-induced damage to the detectors caused by the high α-activity of the 240Pu samples resulted in a deterioration of the detector performance over the data taking period of several months, which compromised the measurement. This obstacle can be eliminated by performing the measurement in EAR-2, where the higher neutron flux will allow collecting data in a much shorter time, thus preventing the degradation of the detectors. In addition to this obvious advantage, the measurement would also benefit from the stronger suppression of the sample-induced α-background, due to the shorter times-of-flight involved.

Shoreline Variation between Puerto Chicama and Puémape, La Libertad, Perú (1961-2006 Variación de la línea de litoral entre puerto Chicama y Puémape, La Libertad, Perú (1961-2006

Directory of Open Access Journals (Sweden)

Carlos Tavares Correa

2010-12-01

Full Text Available A spatial -temporal analysis was made by using cartographic material and Geographic Information Systems techniques. Here we compared the setting of the littoral line of a sector minimally affected by human occupation (Puémape–Puerto Chicama with other sectors with moderate occupation (La Chira–Lurín to strongly modified (Salaverry–Las Delicias and the Miraflores Bay. During the period 1961-2006 in the sector Puémape – Puerto Chicama, we identified the predominance of the advance or stability of the coastal line. The sector La Chira – Lurín presented a setting similar, with the tendency to stability and, the sectors strongly intervened showed a setting openly erosive. To the contrary as expected, the rising of sea level due to global warming doesn’t seem to be the principal cause of beach erosion in Perú. This is mainly due to the strong human intervention in the coast because at undisturbed sectors the predominance is stability or advance of the littoral line.Mediante el empleo de material cartográfico y sistema de información geográfica (SIG, se realizó un análisis espacio-temporal, donde se comparó el comportamiento de la línea de litoral de un sector costero mínimamente afectado por la ocupación humana (Puémape–Puerto Chicama con otros sectores costeros con ocupación moderada (La Chira–Lurín a fuertemente modificada (Salaverry–Las Delicias y la bahía de Miraflores. Durante el período comprendido entre 1961 y 2006 para el sector Puémape–Puerto Chicama, se identificó el predominio del avance o estabilidad de la línea de costa. El sector La Chira–Lurín presentó un comportamiento similar, con tendencia a la estabilidad y los sectores fuertemente intervenidos presentaron un comportamiento netamente erosivo. Al contrario de lo esperado, la elevación del nivel del mar debido el calentamiento global no parece ser la causa principal de la erosión de playas en el Perú. Esta se debe principalmente a la

Distinguishing Pu Metal from Pu Oxide and Determining alpha-ratio using Fast Neutron Counting

Energy Technology Data Exchange (ETDEWEB)

Verbeke, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chapline, G. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nakae, L. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Prasad, M. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sheets, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Snyderman, N. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-01-07

We describe a new method for determining the ratio of the rate of (α, n) source neutrons to the rate of spontaneous fission neutrons, the so called α-ratio. This method is made possible by fast neutron counting with liquid scintillator detectors, which can determine the shape of the fast neutron spectrum. The method utilizes the spectral difference between fission spectrum neutrons from Pu metal and the spectrum of (α, n) neutrons from PuO₂. Our method is a generalization of the Cifarelli-Hage method for determining k_eff for fissile assemblies, and also simultaneously determines k_eff along with the α-ratio.

Simultaneous measurement of {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, and {sup 242}Pu by high resolution inductively coupled plasma mass spectrometer (HR ICP-MS) in marine sediments; Mesure des isotopes du plutonium des sediments marins par spectrometrie de masse a plasma couple inductivement haute resolution (HR ICP-MS)

Energy Technology Data Exchange (ETDEWEB)

Bruneau, F

1999-07-01

Transuranics elements are of particular interest in radioecological studies because of their radiotoxicity and their potential use to decipher source fingerprints and transport processes. The simultaneous measurement of {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, and {sup 242}Pu in environmental samples requires a specific chemical procedure. This work deals with an analytical procedure which yields a very high grade of purification of Pu suitable for ultra low level detection by HR ICP-MS, from marine sediments. After the elimination of major elements (Fe, Al, Mg...) by a first chromatographic separation, a new device of purification by solvent extraction and concentration by a second chromatographic separation is used to obtain a concentrated and high purified solution of plutonium. The chemical procedure have been validated on IAEA certified sediment samples and on sediment samples collected in the roads of Cherbourg which had been previously analysed by other techniques (a spectrometry and thermo-ionisation mass spectrometer). (author)

[Acupuncture messenger--Pu Xiang-cheng].

Science.gov (United States)

Du, Huai-bin; Liang, Fan-rong

2011-06-01

PU Xiang-cheng is the eminent acupuncture master in modern history of China. He studied diligently in early years and devoted his life to the cause of acupuncture practice and education in Chinese medicine. Combination of acupuncture and herbal medicine, coordination of acupuncture and moxibustion, unique application of acupoints, flexible combination of acupoints and focusing on needling techniques are the essence of his academic thoughts. The life of PU Xiang-cheng, the acupuncture master, and his major academic thoughts are described in this paper, so as to commemorate his contributions to acupuncture theory, practice and promotions.

Redefining design criteria for Pu-238 gloveboxes

International Nuclear Information System (INIS)

Acosta, S.V.

1998-01-01

Enclosures for confinement of special nuclear materials (SNM) have evolved into the design of gloveboxes. During the early stages of glovebox technology, established practices and process operation requirements defined design criteria. Proven boxes that performed and met or exceeded process requirements in one group or area, often could not be duplicated in other areas or processes, and till achieve the same success. Changes in materials, fabrication and installation methods often only met immediate design criteria. Standardization of design criteria took a big step during creation of ''Special-Nuclear Materials R and D Laboratory Project, Glovebox standards''. The standards defined design criteria for every type of process equipment in its most general form. Los Alamos National Laboratory (LANL) then and now has had great success with Pu-238 processing. However with ever changing Environment Safety and Health (ES and H) requirements and Ta-55 Facility Configuration Management, current design criteria are forced to explore alternative methods of glovebox design fabrication and installation. Pu-238 fuel processing operations in the Power Source Technologies Group have pushed the limitations of current design criteria. More than half of Pu-238 gloveboxes are being retrofitted or replaced to perform the specific fuel process operations. Pu-238 glovebox design criteria are headed toward process designed single use glovebox and supporting line gloveboxes. Gloveboxes that will house equipment and processes will support TA-55 Pu-238 fuel processing needs into the next century and extend glovebox expected design life

Shape coexistence in 16O, 72Se, and 240Pu: a comprehensive view based on the dynamic deformation model

International Nuclear Information System (INIS)

Kumar, K.

1979-01-01

It has been shown that the gross features of the collective spectra of even-even nuclei ranging from 12 C to 240 Pu are reproduced by the dynamic deformation model without any fitting parameters. We apply another test to be same model in the present study. Can this single model explain three seemingly different types of shape co-existence proposed previously: spherical op-oh and deformed 2p-2h shapes in 16 O, spherical and prolate-deformed minima in the potential energy surface of 72 Se, ground state shape and fission isomer shape of 240 Pu. Of these three nuclei, only the nucleus 72 Se is off the line of beta-stability. The calculated potential energy surfaces and collective spectra of 16 O, 72 Se, and 240 Pu are discussed and compared with experiments. The three different kinds of shape coexistence proposed previously for 16 O, 72 Se, and 240 Pu are all reproduced by the present version of the dynamic deformation model within the same model and without any fitting parameters. We conclude that the combination of the dynamics of the nine-dimensional quadrupole and pairing motions with a large space microscopic calculation provides a rather powerful tool for studying practically all even-even nuclei

Phase equilibrium of PuO{sub 2-x} - Pu{sub 2}O{sub 3} based on first-principles calculations and configurational entropy change

Energy Technology Data Exchange (ETDEWEB)

Minamoto, Satoshi, E-mail: satoshi.minamoto@ctc-g.co.jp [ITOCHU Techno-Solutions Corporation, Kasumigaseki, 2-5, Kasumigaseki 3-chome, Chiyoda-ku, Tokyo 100-6080 (Japan); Kato, Masato [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki (Japan); Konashi, Kenji [Institute for Materials Research, Tohoku University, Oarai-chou, Ibaraki (Japan)

2011-05-31

Combination of an oxygen vacancy formation energy calculated using first-principles approach and the configurational entropy change treated within the framework of statistical mechanics gives an expression of the Gibbs free energy at large deviation from stoichiometry of plutonium oxide PuO{sub 2}. An oxygen vacancy formation energy 4.20 eV derived from our previously first-principles calculation was used to evaluate the Gibbs free energy change due to oxygen vacancies in the crystal. The oxygen partial pressures then can be evaluated from the change of the free energy with two fitting parameters (a vacancy-vacancy interaction energy and vibration entropy change due to induced vacancies). Derived thermodynamic expression for the free energy based on the SGTE thermodynamic data for the stoichiometric PuO{sub 2} and the Pu{sub 2}O{sub 3} compounds was further incorporated into the CALPHAD modeling, then phase equilibrium between the stoichiometric Pu{sub 2}O{sub 3} and non-stoichiometric PuO{sub 2-x} were reproduced.

Investigation on U - O - Na, Pu - O - Na and U,Pu - O - Na phase diagrams

International Nuclear Information System (INIS)

Pillon, S.

1989-03-01

The thermochemical interaction between the nuclear fuel (uranium and plutonium mixed oxides) and the sodium has been investigated and particularly the three phase diagrams: U - O - Na; Pu - O - Na; U,Pu - O - Na. High temperature neutron diffraction, microcalorimetry and powder X-ray diffraction were used for the characterization of the compounds synthetized. This study allowed to complete the knowledge about each of these diagrams and to measure some physical and thermal properties on the compounds. The limits on the modelization of the fuel-sodium interaction are discussed from the results of the UO 2 - Na reaction [fr

Analytical description of transfer of Pu-239 in undisturbed soil

Energy Technology Data Exchange (ETDEWEB)

Tianshan, Ren; Linsalata, P; Cohen, N

1986-04-01

The paper reports on an analytical model for describing the horizontal and down-ward transfer of /sup 239/Pu in undisturbed soil based on observed data. The model has been developed to predict how the depth distribution of /sup 239/Pu in soil would change with time. This information is essential for estimation of the quantities of /sup 239/Pu that have entered surface water body via erosion and runoff processes and for estimation of the long-term impact of /sup 239/Pu isice the commencement of nuclear fallout deposition.

Electrochemical investigations of Pu(IV)/Pu(III) redox reaction using graphene modified glassy carbon electrodes and a comparison to the performance of SWCNTs modified glassy carbon electrodes

International Nuclear Information System (INIS)

Gupta, Ruma; Gamare, Jayashree; Sharma, Manoj K.; Kamat, J.V.

2016-01-01

Highlights: • First report of aqueous electrochemistry of Plutonium on graphene modified electrode. • Graphene is best electrocatalytic material for Pu(IV)/Pu(III) redox couple among the reported modifiers viz. reduced graphene oxide (rGO) and SWCNT’s. • The electrochemical reversibility of Pu(IV)/Pu(III) redox couple improves significantly on graphene modified electrode compared to previously reported rGO & SWCNTs modified electrodes • Donnan interaction between plutonium species and graphene surface offers a possibility for designing a highly sensitive sensor for plutonium • Graphene modified electrode shows higher sensitivity for the determination of plutonium compared to glassy carbon and single walled carbon nanotube modified electrode - Abstract: The work reported in this paper demonstrates for the first time that graphene modified glassy carbon electrode (Gr/GC) show remarkable electrocatalysis towards Pu(IV)/Pu(III) redox reaction and the results were compared with that of single-walled carbon nanotubes modified GC (SWCNTs/GC) and glassy carbon (GC) electrodes. Graphene catalyzes the exchange of current of the Pu(IV)/Pu(III) couple by reducing both the anodic and cathodic overpotentials. The Gr/GC electrode shows higher peak currents (i p ) and smaller peak potential separation (ΔE p ) values than the SWCNTs/GC and GC electrodes. The heterogeneous electron transfer rate constants (k s ), charge transfer coefficients (α) and the diffusion coefficients (D) involved in the electrocatalytic redox reaction were determined. Our observations show that graphene is best electrocatalytic material among both the SWCNTs and GC to study Pu(IV)/Pu(III) redox reaction.

The stability analysis of non-topological solitons in gauge theory and in electrodynamics

International Nuclear Information System (INIS)

Chakrabarti, S.

1982-08-01

The Lyapunov stability analysis of the nontopological soliton solution in the many-charge Qsub(i) Synge Model in non-Abelian SU(2)xU(1) symmetry with the presence of gauge fields is considered. It is shown that in the presence of the subsidiary condition of fixation of charges μsub(i)νsub(i)delta Qsub(i)=0 the necessary condition for stability of the soliton solution (periodic in time with parameters νsub(i)) is defined by the inequality: μsub(i,k) (deltaQsub(i) 0 /deltaνsub(k)) - νsub(i)νsub(k)<0. This condition holds for any Lagrangian density with second-order time derivatives in the presence of gauge fields. This result is extended to the stability analysis of a scalar soliton with electromagnetic field in U(1) symmetry, and it is shown that, in this case, the necessary condition reduces to deltaQsub(i)/deltaν<0. (author)

Transplacental absorption of 238Pu in rats and guinea pigs

International Nuclear Information System (INIS)

Sullivan, M.F.

1980-01-01

Pregnant rats and guinea pigs were injected intravenously with 238 Pu citrate to determine if the potential for in utero accumulation of 238 Pu by these two species is related to the stage of development at which immunity is gained. Although guinea pigs retained more 238 Pu after birth than rats, the difference was not significant

Oxidative stability of polyaniline

Czech Academy of Sciences Publication Activity Database

Stejskal, Jaroslav; Exnerová, Milena; Morávková, Zuzana; Trchová, Miroslava; Hromádková, Jiřina; Prokeš, J.

2012-01-01

Roč. 97, č. 6 (2012), s. 1026-1033 ISSN 0141-3910 R&D Projects: GA ČR GA202/09/1626; GA ČR GAP205/12/0911 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : polyaniline * nanotubes * oxidation stability Subject RIV: BK - Fluid Dynamics Impact factor: 2.770, year: 2012

Detection of Pu in Pacific Ocean water with AMS related to the Fukushima accident

Energy Technology Data Exchange (ETDEWEB)

Hain, Karin; Faestermann, Thomas; Fimiani, Leticia; Guzman, Jose Manuel; Korschinek, Gunther; Kortmann, Florian; Lierse v Gostomski, Christoph; Ludwig, Peter [TUM (Germany); Golser, Robin; Steier, Peter [Universitaet Wien (Austria); Yamada, Masatoshi [Hirosaki University (Japan)

2016-07-01

The concentration of plutonium (Pu) and its isotopic ratios were determined by accelerator mass spectrometry (AMS) in Pacific Ocean water samples. The isotopic ratios {sup 240}Pu/{sup 239}Pu and {sup 241}Pu/{sup 239}Pu can be used to identify a possible release of Pu into the ocean by the Fukushima accident. {sup 241}Pu from fallout of nuclear weapon testings has already significantly decayed. {sup 241}Am, the daughter nuclide of {sup 241}Pu, causes isobaric background on {sup 241}Pu in mass-spectrometric measurements. Therefore, Am and Pu had to be separated chemically using extraction chromatography. The method was verified by analyzing certified reference material. 12 sea water samples, collected at different depths, were prepared at the Radiochemie Muenchen. The concentration of Pu was measured with AMS at the Maier-Leibnitz-Laboratory in Munich and the Vienna Environmental Research Laboratory (VERA). After a short motivation related to the Fukushima accident, the chemical separation method will be presented. Preliminary results of the distribution of Pu in ocean water will be discussed.

Procedure for plutonium determination using Pu(VI) spectra

International Nuclear Information System (INIS)

Walker, L.F.; Temer, D.J.; Jackson, D.D.

1996-01-01

This document describes a simple spectrophotometric method for determining total plutonium in nitric acid solutions based on the spectrum of Pu(VI). Plutonium samples in nitric acid are oxidized to Pu(VI) with Ce(IV) and the net absorbance at the 830 nm peak is measured

Determination of Pu Oxidation states in the HCl Media Using with UV-Visible Absorption Spectroscopic Techniques

International Nuclear Information System (INIS)

Lee, Myung Ho; Suh, Mu Yeol; Park, Kyoung Kyun; Park, Yeong Jae; Kim, Won Ho

2006-01-01

The spectroscopic characteristics of Pu (III, IV, V, VI) in the HCl media were investigated by measuring Pu oxidation states using a UV-Vis-NIR spectrophotometer (400-1200 nm) after adjusting Pu oxidation states with oxidation/reduction reagents. Pu in stock solution was reduced to Pu(III) with NH 2 OH · HCl, and oxidized to Pu(IV) and Pu(VI) with NaNO 2 and HCIO 4 , respectively. Also, Pu(V) was adjusted in the Pu(VI) solution with NH 2 OH · HCl. The major absorption peaks of Pu (IV) and Pu(III) were measured in the 470 nm and 600 nm, respectively. The major absorption peaks of Pu (VI) and Pu(V) were measured in the 830 nm and 1135 nm, respectively. There was not found to be significant changes of UV-V is absorption spectra for Pu(III), Pu(IV) and Pu(VI) with aging time, except that an unstable Pu(V) immediately reduced to Pu(III).