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173 results on '"European Commission - Joint Research Centre [Karlsruhe] (JRC)"'

151. Characterization of the NIST seaweed Standard Reference Material

Author

L. Aldave de las Heras, Ian W. Croudace, Arvic Harms, G. A. Peck, Iisa Outola, Joan-Albert Sanchez-Cabeza, Dirk Arnold, P. A. Smedley, Gi Hoon Hong, Kenneth G. W. Inn, L.K. Fifield, P. Bouisset, Tarja K. Ikäheimonen, Elis Holm, A. Raaum, S. Bohrer, M. K. Pham, A. E. Litherland, D. S. Sill, A Arinc, M. P. Anton, J. Twining, Maria Betti, Lindis Skipperud, G. C. Krijger, James J. Filliben, Pavel P. Povinec, M. J. Youngman, Phillip E. Warwick, S. Klemola, H. J. Wei, H. Wershofen, C. Gasco, S. M. Vakulovsky, Stephen G. Tims, J. La Rosa, Henning Dahlgaard, C. A. McMahon, William E. Kieser, National Institute of Standards and Technology [Gaithersburg] (NIST), Australian Nuclear Science and Technology Organization, Australian National University (ANU), The Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Centro de Investigaciones Energéticas Medioambientales y Tecnológicas [Madrid] (CIEMAT), Marine Environment Laboratories [Monaco] (IAEA-MEL), International Atomic Energy Agency [Vienna] (IAEA), Institute for Energy Technology (IFE), Interfaculty Reactor Institute, Delft University of Technology (TU Delft), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), IsoTrace Laboratories, University of Toronto, JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Korean Ocean Research and Development Institute (KORDI), Lund University [Lund], Agricultural University of Norway, National Physical Laboratory [Teddington] (NPL), National Radiological Protection Board (NRPB), Physikalisch-Technische Bundesanstalt [Braunschweig] (PTB), Risø National Laboratory, Danish Ministry of Science, Technology and Innovation, National Oceanography Centre [Southampton] (NOC), University of Southampton, Radiation and Nuclear Safety Authority [Helsinki] (STUK), and Universitat Autònoma de Barcelona (UAB)

Subjects
Water Pollutants, Radioactive, radioisotope decay, International Cooperation, Characterization, Median methods, [SDV]Life Sciences [q-bio], Mineralogy, chemistry.chemical_element, Guidelines as Topic, 010403 inorganic & nuclear chemistry, Radiation Dosage, 01 natural sciences, Sensitivity and Specificity, thorium, uranium, Reference Values, radioisotope, Evaluation, intermethod comparison, Radioisotopes, Radionuclide, analytic method, Radiation, nonhuman, Waste management, 010401 analytical chemistry, article, Thorium, Reproducibility of Results, reference value, standard, Uranium, Reference Standards, technique, Seaweed, 0104 chemical sciences, Natural decay series, Certified reference materials, Radioactivity, chemistry, priority journal, Intermethod comparison, Thorium series, NIST, radiation measurement, radiation monitoring
Abstract

The National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for seaweed was developed through an interlaboratory comparison with 24 participants from 16 countries. After evaluating different techniques to calculate certified values for the radionuclides, the median method was found to be the most representative technique. The certified values were provided for 13 radionuclides and information values were given for 15 more radionuclides. Results for the natural decay series showed disequilibrium in both the uranium and thorium series. © 2006 Elsevier Ltd. All rights reserved.

Published
2006

152. Electrochemical behaviour of americium ions in LiClKCl eutectic melt

Author

Rikard Malmbeck, Pierre Chamelot, Rudy J. M. Konings, S. Fourcaudot, Jean-Paul Glatz, Jean-Claude Poignet, Carole Pernel, Jean Rebizant, Jérôme Serp, JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI ), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de génie chimique [ancien site de Basso-Cambo] (LGC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, and Institut de Chimie du CNRS (INC)-Institut National Polytechnique de Grenoble (INPG)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)

Subjects
Cyclic voltammetry, Square wave voltammetry, 020209 energy, General Chemical Engineering, LiCl–KCl, Inorganic chemistry, Analytical chemistry, 02 engineering and technology, Electrochemistry, 7. Clean energy, Redox, Thermodynamic properties, symbols.namesake, TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, 0202 electrical engineering, electronic engineering, information engineering, Qualitative inorganic analysis, Diffusion coefficient, Eutectic system, Americium, Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Standard enthalpy of formation, Gibbs free energy, symbols, 0210 nano-technology
Abstract

International audience; This work presents a study on the electrochemical properties of AmCl3 in a molten LiCl–KCl eutectic, at a temperature range of 733–833 K. Transient electrochemical techniques, such as cyclic voltammetry and chronopotentiometry, on inert metallic tungsten working electrode have been used to investigate the reduction mechanism of Am3+ ions. The results show that Am3+ is reduced to Am metal by a two-step mechanism corresponding to the Am3+/Am2+ and Am2+/Am0 transitions. Formal standard potentials of Am3+/Am2+ (E0′ Am3+/Am2+ = -2.695 V versus Cl2/Cl– at 733 K) and Am2+/Am0 (E0′ Am2+/Am0 = -2.911 V versus Cl2/Cl– at 733 K) redox couples as well as diffusion coefficients of Am3+ and Am2+ (2.4 × 10–5 and 1.15 × 10–5 cm2 s–1 at 733 K, respectively) have been calculated at three different temperatures. In the studied range of temperature, the DAm3+/DAm2+ ratio was found to be around 2. In addition, thermodynamic properties have been calculated for Am3+ (ΔG∞AmCl3= -933.7 + 0.152 T) and Am2+ (ΔG∞AmCl2= -623.9 + 0.085 T) and compared to thermodynamic reference data in order to estimate activity coefficients (Am3+ = 4.7 × 10–3 and Am2+ = 2.7 × 10–2 at 733 K) in the molten LiCl–KCl eutectic.

Published
2006

153. Evaluation of samplers and filter materials for the establishment of trace metal concentration profiles in peat bog porewaters using inductively coupled plasma-mass spectrometry

Author

William Shotyk, N. Rausch, Liisa Ukonmaanaho, Tiina M. Nieminen, Gaël Le Roux, Michael Krachler, Institute of environmental geochemistry (Heidelberg, DE), Universität Heidelberg [Heidelberg], JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Finnish Forest Research Institute (METLA), Natural Resources Institute Finland (LUKE), and Institut de Radioprotection et de Sûreté Nucléaire (IRSN)

Subjects
010504 meteorology & atmospheric sciences, Magnesium printing plates, Analytical chemistry, Filters (for fluids), 010501 environmental sciences, 01 natural sciences, Biochemistry, Analytical Chemistry, law.invention, Porewater, molybdenum, law, water sampling, Trace metal, Inductively coupled plasma mass spectrometry, Spectroscopy, mass spectrometry, filter, Chemistry, zinc, article, trace element, Contamination, cobalt, 6. Clean water, priority journal, Environmental chemistry, manganese, Sample collection, chromium, Inductively coupled plasma, cadmium, Water filtration, Mass spectrometry, nickel, Rivers, Trace metals, syringe, Environmental Chemistry, ICP-MS, [CHIM]Chemical Sciences, Filtration, 0105 earth and related environmental sciences, filtration, lead, Peat, sampler, Trace element, Water, Trace analysis, copper, vanadium, Analytical procedures, peatland
Abstract

Two different types of sampler were used for the collection of humic-rich porewaters from ombrotrophic bogs at background and contaminated sites: a syringe-type sampler, which required manual filtration and dialysis chambers (peepers) where samples were filtered in situ. Concentrations of 10 trace elements Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V and Zn have been determined in the collected porewater samples using inductively coupled plasma-sector-field-mass spectrometry. The accuracy of the analytical procedures was evaluated by the regular analyses of the two certified riverine water reference materials SLRS-2 and SLRS-4, respectively. For the syringe-type sampler, four different 0.45 μm syringe filters were tested. Low blank values together with sufficiently low filtration artefacts were obtained using unwashed GD/XP filters (Whatman). When pre-cleaned filters were used, Cu and Mo showed strong filtration artefacts. Mean metal concentrations of filtrates differed by up to five times, depending on the filter type used. Overall blank values of the sampling devices were as follows (ng l-1): Cd 1, Co 9, Cr 50, Cu 70, Mn 200, Mo 20, Ni 100, Pb 4, V 10, Zn 1000. The contribution of atmospheric dust during the on-site filtration might have enhanced overall blank levels of Cr, Cu and Zn when protective covers were not used during sample collection/on-site filtration. Metal concentrations at background sites were at ng l-1 levels except for Zn and Mn (low μg l-1). With the exception of Co and Mn, dialysis chambers were not suitable for sampling porewaters at these concentration levels. © 2005 Elsevier B.V. All rights reserved.

Published
2006

154. Magnetic multipole order and symmetry considerations on the ground state of Np4+ ions in NpO2

Author

F. Wastin, Roberto Caciuffo, Nicola Magnani, Jean Rebizant, S. Di Matteo, Laboratori Nazionali di Frascati (LNF), Istituto Nazionale di Fisica Nucleare (INFN), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), and European Commission - Joint Research Centre [Karlsruhe] (JRC)

Subjects
Scattering, Chemistry, Mechanical Engineering, Actinide dioxides, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Energy level splitting, Metals and Alloys, Multipolar order, Point group, 01 natural sciences, Computer Science::Digital Libraries, Symmetry (physics), 010305 fluids & plasmas, 75.25.+z, 75.10.− b, Mechanics of Materials, 0103 physical sciences, Quadrupole, Materials Chemistry, Computer Science::Mathematical Software, Singlet state, Atomic physics, 010306 general physics, Multipole expansion, Ground state, Crystal field
Abstract

International audience; The ground-state symmetries of Np ions in the low temperature phase of NpO2 are discussed with reference to the results of resonant X-ray scattering experiments suggesting the occurrence of long-range multipolar order with electric quadrupole secondary order parameter. Two models have been proposed in the literature: one based on a View the MathML source doublet (in D3d point group), the other on a View the MathML source (View the MathML source) singlet. We show, through a theoretical group analysis, that the View the MathML source doublet is not compatible with the available experimental data. Our analysis supports the hypothesis of a singlet ground state.

Published
2006

155. A Knudsen cell-mass spectrometer facility to investigate oxidation and vaporisation processes in nuclear fuel

Author

J.-P. Hiernaut, J. Jonnet, Claudio Ronchi, J.-Y. Colle, R. Pflieger-Cuvellier, Joseph Somers, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Nuclear and High Energy Physics, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Mass spectrometry, 01 natural sciences, 7. Clean energy, Oxygen, 010305 fluids & plasmas, law.invention, chemistry.chemical_compound, law, 0103 physical sciences, Uranium oxide, General Materials Science, Nuclear fuel, Spectrometer, Electromotive force, Nuclear reactor, 021001 nanoscience & nanotechnology, Nuclear Energy and Engineering, chemistry, 13. Climate action, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Sublimation (phase transition), 0210 nano-technology
Abstract

International audience; Vaporisation processes in uranium oxide fuel were investigated under controlled oxidation conditions. A Knudsen cell with a mass spectrometer was adapted to feed an adjustable oxygen flux up to temperatures of 1900 K producing an oxygen pressure in the cell ranging up to 1000 Pa. Experiments were carried out on fresh and irradiated fuels, both pre-oxidised to U3O8 or oxidised online in the Knudsen cell, to measure effects associated with fuel sublimation in the form of different uranium-bearing oxides. Mass spectrometry, electromotive force measurements and thermo-gravimetric analysis were used to determine the vapour equilibrium conditions at fixed free oxygen potentials.

Published
2005

156. Uranium Form Factors in Selected UTX Compounds

Author

Pavel Javorský, Schweizer, J., Givord, F., Boucherle, J. X., Sechovsky, V., Andreev, A. V., Lelievre-Berna, E., Bourdarot, F., JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), J. Heyrovský Institute of Physical Chemistry of the ASCR, Czech Academy of Sciences [Prague] (CAS), Institut Laue-Langevin (ILL), and Charles University [Prague] (CU)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

International audience

Published
2003

157. Magnetization densities in UPtAl studied by polarized neutron diffraction

Author

Javorsky, Pavel, Givord, Françoise, Boucherle, Jean-Xavier, Lelievre-Berna, Eddy, Andreev, Alexander, Sechovsky, Vladimir, Bourdarot, F., JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Charles University [Prague] (CU), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Laue-Langevin (ILL), and Kuznietz, M

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

International audience

Published
2002

158. Coherent magnetic diffraction from the uranium M4 edge in the multi-k magnet, USb

Author

G. H. Lander, Roberto Caciuffo, Nicola Magnani, Elizabeth Blackburn, A. Bombardi, Francis Livet, J. A. Lim, Guillaume Beutier, School of Physics and Astronomy, University of Birmingham [Birmingham], Science et Ingénierie des Matériaux et Procédés (SIMaP), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Institut National Polytechnique de Grenoble (INPG), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), and DIAMOND Light source

Subjects
Diffraction, Physics, History, Condensed matter physics, Magnetic domain, business.industry, Scattering, Bragg peak, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Computer Science Applications, Education, Quality (physics), Optics, Spin wave, Magnet, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Antiferromagnetism, 010306 general physics, 0210 nano-technology, business
Abstract

International audience; The slow magnetic dynamics, from seconds to kiloseconds, of the canonical 3-k antiferromagnet USb have been probed, using X-ray photon correlation spectroscopy (XPCS). In this work, XPCS is combined with resonant X-ray diffraction to focus on scattering at an antiferromagnetic Bragg peak. High quality coherent magnetic diffraction patterns were recorded (speckle contrast of ~ 88%) and magnetic domains were observed; the number of domains increases on warming to T* ~ 160 K, where the spin waves soften to zero frequency, and again on warming to TN = 218 K. The intensity auto-correlation, g2(t), is primarily static over 1000 s, with a small dynamical process (change of ~ 0.4%) that increases in rate close to the transitions.

Published
2014

159. Spin and orbital moments in itinerant magnets

Author

G. H. Lander, M. S. S. Brooks, P. J. Brown, R. Troć, A. Czopnik, P. Burlet, S. Coad, A. Hiess, Dariusz Kaczorowski, F. Boudarot, Institut Laue-Langevin (ILL), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de Recherche Fondamentale sur la Matière Condensée (DRFMC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), and Polish Academy of Sciences (PAN)

Subjects
Physics, Scattering amplitude, Momentum, Magnetization, Angular momentum, Ferromagnetism, Condensed matter physics, Neutron diffraction, General Physics and Astronomy, Antiferromagnetism, Condensed Matter::Strongly Correlated Electrons, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Spin (physics)
Abstract

Itinerant magnets with large orbital moments are uncommon. We show that UGa3 is such a material where the itinerant magnetism is carried by the 5f states. The definitive evidence comes from neutron diffraction measurements of the magnetization distribution, where a significant difference is observed in the momentum dependence of the scattering amplitude above and below TN. The change in the magnetization distribution when the antiferromagnetic order appears is due to the antiparallel coupling of large atomic 5f spin and orbital moments below TN, whereas above TN there is spin degeneracy and no disordered local moments.

Published
2001

160. Evolution of magnetic structures in NpAs_1-xSe_x solid solutions

Author

Bombardi, A., Bourdarot, F., Burlet, P., Sanchez, J. P., Vulliet, P., Colineau, E., Rebizant, J., Wastin, F., Lander, G. H., Vogt, O., Mattenberger, K., Département de Recherche Fondamentale sur la Matière Condensée (DRFMC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratorium für Festkorperphysik [ETH Zürich], Departement Physik [ETH Zürich] (D-PHYS), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

We report Mössbauer spectroscopy, magnetization, and neutron-diffraction measurements on four samples (x=0.05,0.10,0.15, and 0.20) in the mixed system NpAs1−xSex. The evolution of magnetic phase diagram vs the temperature T and the Se concentration x has been determined. Up to x=0.15, three distinct phase transitions are present. The first antiferromagnetic (AF) at TN(x) is from paramagnetism to an incommensurate phase, the second, at TC(x), is to a ferromagnetic (FM) phase, the third at Tm(x) is from pure FM to a mixed phase where AF and FM ordering coexist along perpendicular directions. The temperatures of the transitions are functions of Se concentration x. The incommensurate structure is described by a longitudinal amplitude modulated sinusoidal wave with a wave vector →k in the range (000.14–0.24) that is shifted toward the center of the Brillouin zone with increasing x. A squaring up of this wave, if present, is too small to be detected. At TC(x) all Np sites become equivalent and the moment directions become ⟨111⟩. Surprisingly, at Tm(x) AF interactions again become important and cause the moments to rotate and to align along ⟨221⟩ directions. Measurements in an external magnetic field up to 4.8 T have allowed us to determine the 1→k nature of the AF component for T

Published
2000

161. Magnetic structure of HoBe_13 in an applied magnetic field

Author

Dervenagas, P., Burlet, P., Bonnet, M., Bourdarot, F., Hiess, A., Bud'Ko, S. L., Canfield, P. C., Lander, G. H., Kim, J. S., Stewart, G. R., Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Génétique Expérimentale en Productions Animales (GEPA), Institut National de la Recherche Agronomique (INRA), Institut Laue-Langevin (ILL), Ames Laboratory [Ames, USA], Iowa State University (ISU)-U.S. Department of Energy [Washington] (DOE), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), and University of Florida [Gainesville] (UF)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

The magnetic structure of HoBe13 and its evolution under an applied magnetic field have been examined using neutron diffraction and bulk magnetization measurements on a single crystal. In the absence of an external field this cubic compound orders at TN=5.7(1)K into a regular helical magnetic structure with propagation vector k=[0013]. Third-order harmonics appear at 4.4(1) K and are attributed to a deformation of the helical structure below this temperature. When a magnetic field is applied along a [001] axis two magnetic transitions occur. First the magnetic domain with propagation vector parallel to the field is favored and, with the addition of the induced ferromagnetic component, by about 4 kG we have a single-domain conical structure. The surprising observation was that at higher fields (15 kG at 1.4 K) the other two domains reappear and become the preferred ones. This reentrant behavior is due to the change of the magnetic structure to a canted arrangement, involving a ferromagnetic component along the applied field and a transverse collinear antiferromagnetic component. When the magnetic field is applied along a [110] axis only one transition is observed from the helical to the conical structure. The magnetic phase diagram of HoBe13 has been constructed.

Published
2000

162. Collapse of the magnetic ordering and structural anomalies in the U La S system: neutron diffraction and specific heat measurements

Author

P. Burlet, G. H. Lander, A. Bombardi, Kurt Mattenberger, O. Vogt, J.P. Sanchez, F. Lapierre, R. Calemczuk, Frederic Bourdarot, Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Laboratorium für Festkorperphysik [ETH Zürich], Departement Physik [ETH Zürich] (D-PHYS), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)

Subjects
Range (particle radiation), Materials science, Condensed matter physics, Solid-state physics, Neutron diffraction, Crystal structure, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Lattice constant, Nuclear magnetic resonance, Ferromagnetism, Anomaly (physics), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Solid solution
Abstract

International audience; We report specific heat and neutron diffraction measurements of seven samples in the solid solution system UxLa1-xS. All samples have the simple fcc NaCl crystal structure. Both specific heat and neutron diffraction confirm the suggestion from the earlier magnetic measurements that the ferromagnetism disappears abruptly at 0.57. Near there is a doubling of the electronic contribution to the specific heat, as compared to the value of 23 mJ mol-1K-2 in pure US. Around the widths of the nuclear Bragg peaks show a considerable broadening, as well as anomalies in the mean lattice parameter, as compared to those expected from Vegard's law. A preliminary analysis suggests this broadening may be due to a loss of long range lattice order near . However, these changes are independent of temperature, so that further experiments are necessary before they can be associated with the changes in magnetic behavior at .

Published
1999

163. Neutron diffraction on a UGa₃ single crystal

Author

Dervenagas, P, Kaczorowski, D, Bourdarot, F., Burlet, P, Czopnik, A, Lander, G.H, Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Polish Academy of Sciences (PAN), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), and European Commission - Joint Research Centre [Karlsruhe] (JRC)

Subjects
Actinides, Itinerant antiferromagnetism, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Neutron diffraction
Published
1999

164. Magnetic structure of NpPd₂Al₃: Relevance to the coexistence of superconductivity and magnetism in UPd₂Al₃

Author

Hiess, A., Bourdarot, F., Burlet, P., Ressouche, Eric, Sanchez, J.-P., Wastin, F., Rebizant, J., Lander, G. H., Suard, E., JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Institut Laue-Langevin (ILL)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

We report neutron-diffraction experiments to determine the low-temperature magnetic structure of NpPd2Al3, the isostructural Np analog of the heavy-fermion superconductor UPd2Al3. The systems orders initially at about 40 K with an incommensurate magnetic propagation vector q=(,,0.36). Below 25nK the intensity of this phase is reduced and a new commensurate magnetic phase with q=(,,) is observed as the dominant phase. The fact that we observe two magnetic phases in this system may have relevance to understanding the ground state in UPd2Al3.

Published
1997

165. A single-crystal magnetization and neutron scattering investigation of the magnetic structure of U₂Rh₂Sn

Author

José A. Paixão, F. Boudarot, Jean Rebizant, Laura C. J. Pereira, Pedro Estrela, Maria Helena Godinho, J.C. Spirlet, Manuel Almeida, M. Bonnet, JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Universidade de Coimbra [Coimbra], Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Instituto Tecnológico e Nuclear (ITN), and ITN

Subjects
Neutron magnetic moment, Magnetic moment, Magnetic structure, Condensed matter physics, Chemistry, Neutron scattering, Condensed Matter Physics, Tetragonal crystal system, Magnetization, Crystallography, Magnetic anisotropy, Condensed Matter::Strongly Correlated Electrons, General Materials Science, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Single crystal
Abstract

U₂Rh₂Sn is a member of a large family of intermetallic compounds with the tetragonal crystal structure. It orders antiferromagnetically at with the propagation vector k = (0,0,1/2). We have performed magnetization and neutron scattering experiments on a single crystal that show that the uranium atoms order in the collinear irreducible representation of the magnetic group, with the moments aligned parallel to the unique tetragonal axis. The value of the ordered magnetic moment of the uranium atoms refined from the neutron scattering intensities is . This is considerably reduced from the free-ion value for both and configurations and suggests that the f electrons are strongly hybridized with the conduction band.

Published
1996

166. Magnetic structure and properties of NpS and NpSe

Author

O. Vogt, A. Blaise, P. Burlet, M.N. Bouillet, Frederic Bourdarot, Jean Rebizant, J. P. Sanchez, J. Rossat-Mignod, J.C. Spirlet, Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Laboratorium für Festkorperphysik [ETH Zürich], Departement Physik [ETH Zürich] (D-PHYS), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)

Subjects
Nuclear magnetic resonance, Materials science, Condensed matter physics, Magnetic structure, Mössbauer spectroscopy, Neutron diffraction, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Condensed Matter Physics, Single crystal, Electronic, Optical and Magnetic Materials
Abstract

Single crystal neutron diffraction measurements on NpS and NpSe show that both compounds order AF at T N = 23 and 38 K, respectively, with a type II multi- k structure leading to non-equivalent Np sites, as shown by Mossbauer results.

Published
1992

167. Magnetic excitations in NpBi

Author

P. Bossy, Frederic Bourdarot, J.C. Spirlet, P. Burlet, L. P. Regnault, Jean Rebizant, G. H. Lander, B. Fåk, Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Laue-Langevin (ILL), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), and European Commission - Joint Research Centre [Karlsruhe] (JRC)

Subjects
Physics, Condensed matter physics, Neutron scattering, Condensed Matter Physics, Inelastic neutron scattering, Electronic, Optical and Magnetic Materials, Actinides, Transverse plane, type-I antiferromagnetism, Magnetic excitations, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Electrical and Electronic Engineering, Atomic physics, Single crystal, Excitation
Abstract

Proceedings of the First European Conference on Neutron Scattering; International audience; We report inelastic neutron scattering measurements on a single crystal of NpBi. The observed magnetic excitation spectrum has two branches: one with longitudinal and the other with transverse polarisation. This is in agreement with the prediction of Jensen and Bak concerning the magnetic excitations in the triple-k type-I structure.

Published
1997

168. Magnetic properties of single crystalline NpAs-NpSe mixed compounds

Author

J. Rossat-Mignod, O. Vogt, M.N. Bouillet, Jean Rebizant, J.C. Spirlet, Frederic Bourdarot, P. Burlet, Kurt Mattenberger, J. P. Sanchez, A. Blaise, Laboratorium für Festkorperphysik [ETH Zürich], Departement Physik [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Physics, Magnetic domain, Condensed matter physics, Condensed Matter Physics, Electron magnetic dipole moment, Magnetic susceptibility, Electronic, Optical and Magnetic Materials, Magnetic field, Condensed Matter::Materials Science, Magnetic anisotropy, Ferrimagnetism, Nuclear magnetic moment, Physics::Atomic and Molecular Clusters, Condensed Matter::Strongly Correlated Electrons, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Magnetic dipole
Abstract

The antiferromagnetic 3k-structure of NpAs transformes to a ferrimagnetic one in magnetic fields

Published
1992

169. Influence of corium oxidation on fission product release from molten pool

Author

G. Ducros, V.B. Khabensky, Luis E. Herranz, S. A. Vitol, D. Bottomley, Sevostian Bechta, B. Clément, V. V. Gusarov, Ari Auvinen, E.V. Krushinov, Christophe Journeau, S. Guentay, A.A. Sulatsky, S.Yu. Kotova, V. I. Al’myashev, V. V. Bezlepkin, K. Trambauer, Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Commission - Joint Research Centre [Karlsruhe] (JRC), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Centro de Investigaciones Energéticas Medioambientales y Tecnológicas [Madrid] (CIEMAT), Paul Scherrer Institute (PSI), Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH, and VTT Technical Research Centre of Finland (VTT)

Subjects
Nuclear and High Energy Physics, Nuclear fission product, Molten pool, Induction heating, Materials science, 020209 energy, Crucible, Experimental data, Melt oxidation, 02 engineering and technology, Fission products, Corium, 01 natural sciences, law.invention, Cold crucibles, Quantitative determinations, Nuclear physics, law, 0103 physical sciences, Oxidation, 0202 electrical engineering, electronic engineering, information engineering, General Materials Science, Test facilities, Safety, Risk, Reliability and Quality, Melt surfaces, Waste Management and Disposal, Aerosol-particle composition, Volatile fission products, 010302 applied physics, [PHYS]Physics [physics], Molten materials, Mechanical Engineering, Metallurgy, Oxidation indices, Nuclear reactor, Nuclear Energy and Engineering, Nuclear reactor core, Coremaking, Particle size, Core material
Abstract

Qualitative and quantitative determination of the release of low-volatile fission products and core materials from molten oxidic corium was investigated in the EVAN project under the auspices of ISTC. The experiments carried out in a cold crucible with induction heating and RASPLAV test facility are described. The results are discussed in terms of reactor application; in particular, pool configuration, melt oxidation kinetics, critical influence of melt surface temperature and oxidation index on the fission product release rate, aerosol particle composition and size distribution. The relevance of measured high release of Sr from the molten pool for the reactor application is highlighted. Comparisons of the experimental data with those from the COLIMA CA-U3 test and the VERCORS tests, as well as with predictions from IVTANTHERMO and GEMINI/NUCLEA codes are made. Recommendations for further investigations are proposed following the major observations and discussions. © 2010 Elsevier B.V. All rights reserved.

170. Influence of plutonium on the thermodynamic properties and phase equilibria in corium

Author

Stéphane Gossé, Gueneau, C., Quaini, A., Dupin, N., Bonnaillie, P., Manara, D., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Calcul Thermodynamique, JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), and amplexor, amplexor

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], Calphad, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Thermodynamics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], MOX fuel, Severe accident
Abstract

International audience; During a severe accident in a pressurized water reactor, very high temperatures can be reached (T>2500 K). In these conditions, the UO$_2$ or mixed oxide (U,Pu)O$_2$ nuclear fuel shall react with the Zircaloy cladding and then with the steel vessel, forming a complex mixture of solid and liquid phases called in-vessel corium. At very high temperature, the corium can be constituted of two metallic and oxide liquid phases due to the existence of a miscibility gap in the liquid state. The relative fraction and composition of these phases that form in the corium as a function of temperature are key input data for severe accident codes to predict corium thermal-hydraulics properties.The TAF-ID thermodynamic database [1] coupled to software like Thermo-Calc or Open Calphad is a powerful computational tool to predict the thermodynamic data of nuclear fuel materials. The database is developed using the Calphad method on the basis of the available experimental data. In case of severe accident applications, experimental data are missing, especially on systems containing plutonium. New measurements of thermodynamic and phase diagram data on subsystems of the prototypic in-vessel corium U-Pu-Zr-Fe-O are required. Such experiments are particularly difficult to carry out due to radiotoxicity of the materials and to the very high temperature level. New measurements using advanced laser melting techniques will be presented. The models derived from these new experimental data will be described. Finally the influence of the presence of plutonium in the mixed oxide fuel on the thermodynamic properties and phase equilibria of the in-vessel corium will be investigated by thermodynamic calculations.

171. Preparation of a new water soluble polynuclear peroxide complex of Pu(IV)

Author

Matthieu Virot, Dalodière, E., Dumas, T., Blanco, O. D., Wiss, T., Moisy, P., Nikitenko, S. I., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Commission - Joint Research Centre [Karlsruhe] (JRC), CEA-DEN, and CADARACHE, Bibliothèque

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], Redox, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Ultrasons, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Sonochimie, Plutonium, Peroxides
Abstract

International audience; Due to its acido-basic, complexing and redox properties, hydrogen peroxide has been widely used in nuclear research and industry. Particularly, this salt-free reagent has been highly considered for the stabilization of Pu(IV) in acid conditions and the precipitation of Pu peroxides as precursors for PuO$_2$ preparation. The addition of H$_2$O$_2$ to Pu(VI) acid solutions allows its conversion into Pu(V) which disproportionates and allows the accumulation of Pu(IV).[1] Further addition of H$_2$O$_2$ may lead to Pu(III), or a mixture of Pu(IV) and Pu(III), through the generation of a Pu(IV) peroxo complexe which decompose in acid conditions.[1,2] The continuous addition of H$_2$O$_2$ to Pu(IV) acid solutions leads to the progressive formation of a brown peroxo complex which turns red before insoluble plutonium peroxide precipitate.[2,3] The structure of these complexes which have been postulated in 1949 still remains under debate. Since, only one Pu peroxo structure has been recently proposed and concerned a dimeric molecular compound prepared in alkaline conditions.[4] The current study focuses on the behavior of Pu(IV) aqueous solutions in slightly acid conditions in the presence of hydrogen peroxide. We particularly describe the first observation of a water soluble polynuclear peroxo complex of Pu(IV) which has, up to our knowledge, never been reported in the literature.

172. Perspectives in using Raman spectroscopy for characterizing the microstructure of plutonium-bearing materials

Author

Laeticia Medyk, Patrick Simon, Aurélien Canizarès, Dario Manara, Konings, Rudy J. M., Jean-Yves Colle, Romain Vauchy, Christophe Valot, Gilles Montagnac, Martin, Philippe M., Service d’étude des procédés de Fabrication des Matériaux d’Actinides (SFMA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université d'Orléans (UO), European Commission - Joint Research Centre [Karlsruhe] (JRC), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), CADARACHE, Bibliothèque, Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; In the frame of the development of uranium-plutoniummixed oxide fuels for Sodium-cooled Fast Reactors (SFRs),characterizing nuclear materials by various techniques isparamount.These fast neutron reactors imply the use of a (U,Pu)O$_{2-x}$ceramic fuel with a Pu/(U+Pu) content between 19 and30 mol.%. Furthermore, the physico-chemical andmicrostructural properties of such fuels, such as chemicalhomogeneity, oxygen stoichiometry (O/(U+Pu) ratio) andcrystallographic structure, have to meet precise criteria forbeing introduced in the reactor core.

173. In situ high-temperature EXAFS measurements on radioactive and air-sensitive molten salt materials.

Author

Smith AL, Verleg MN, Vlieland J, de Haas D, Ocadiz-Flores JA, Martin P, Rothe J, Dardenne K, Salanne M, Gheribi AE, Capelli E, van Eijck L, and Konings RJM

Abstract

The development at the Delft University of Technology (TU Delft, The Netherlands) of an experimental set-up dedicated to high-temperature in situ EXAFS measurements of radioactive, air-sensitive and corrosive fluoride salts is reported. A detailed description of the sample containment cell, of the furnace design, and of the measurement geometry allowing simultaneous transmission and fluorescence measurements is given herein. The performance of the equipment is tested with the room-temperature measurement of thorium tetrafluoride, and the Th-F and Th-Th bond distances obtained by fitting of the EXAFS data are compared with the ones extracted from a refinement of neutron diffraction data collected at the PEARL beamline at TU Delft. The adequacy of the sample confinement is checked with a mapping of the thorium concentration profile of molten salt material. Finally, a few selected salt mixtures (LiF:ThF 4 ) = (0.9:0.1), (0.75:0.25), (0.5:0.5) and (NaF:ThF 4 ) = (0.67:0.33), (0.5:0.5) are measured in the molten state. Qualitative trends along the series are discussed, and the experimental data for the (LiF:ThF 4 ) = (0.5:0.5) composition are compared with the EXAFS spectrum generated from molecular dynamics simulations., (open access.)

Published
2019
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