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1. Microstructural characteristics of a fresh U(Mo) monolithic mini-plate: Focus on the Zr coating deposited by PVD

Author

Xavière Iltis, Doris Drouan, Thierry Blay, Isabelle Zacharie, Catherine Sabathier, Claire Onofri, Christian Steyer, Christian Schwarz, Bruno Baumeister, Jérôme Allenou, Bertrand Stepnik, and Winfried Petry

Subjects
U(Mo), Monolithic, Coating, Microstructure, Nuclear engineering. Atomic power, TK9001-9401
Abstract

Within the frame of the EMPIrE test, four monolithic mini-plates were irradiated in the ATR reactor. In two of them, the monolithic U(Mo) foil had been PVD-coated with Zr before the plate manufacturing. Extensive microstructural characterizations were performed on a fresh archive mini-plate, using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS), Electron Backscattered Diffraction (EBSD) and Focused Ion Beam (FIB)/Transmission Electron Microscopy (TEM) with nano EDS. A particular attention was paid to the examination of the U(Mo) foil, the PVD coating, the cladding/Zr and Zr/U(Mo) interfaces.The Zr coating has a thickness around 15 μm. It has a columnar microstructure and appears dense. The cohesion of the cladding/Zr and Zr/U(Mo) interfaces seems to be satisfactory. An almost continuous layer with a thickness of the order of 100–300 nm is present at the cladding/Zr interface and corresponds to an oxidized part of the Zr coating. At the Zr/U(Mo) interface, a thin discontinuous layer is observed. It could correspond to locally oxidized U(Mo).This work provides a basis for interpreting the results of characterizations on EMPIrE irradiated plates.

Published
2021
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2. Morphological and microstructural characterizations of the fresh fuel plates for the SEMPER FIDELIS in-pile test

Author

Mira Khair, François Housaer, Nicolas Hibert, Jérôme Allenou, Ahmed Addad, Franck Beclin, Matthieu Touzin, Ann Leenaers, Hervé Palancher, Bertrand Stepnik, Olivier Tougait, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Unité Matériaux et Transformations - UMR 8207 (UMET), and Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
Interface layer, Nuclear and High Energy Physics, Nuclear Energy and Engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Low-enriched-uranium (LEU), ZrN, General Materials Science, Si, Mo coating, [CHIM.MATE]Chemical Sciences/Material chemistry, UMo dispersion fuel, SEMPER FIDELIS
Abstract

International audience; The UMo/Al dispersion fuel in plate form is considered for the conversion of high-performance research reactors in Europe. In the framework of the UMo fuel qualification program, the adequate margin of safety performance by considering several technological solutions associated with the fabrication parameters, such as heat-treatment of the UMo particles, coating with a diffusion barrier material and powder size distribution as some examples. All these parameters, along with the effect of the hot-rolling process were evaluated by means of image processing and detailed microstructural characterizations for fresh samples i.e. prior to irradiation tests. Principle macroscopic features of powder batches include the size and shape distributions and coating surface examinations. Microscale investigations explored both the coating and kernel microstructures as well as the interface layer between them. Finally, nanoscale analyses examined the UMo–coating interface. The extensive stresses associated with the hot-rolling process have a significant impact on the deformation of the UMo kernels and the degradation of the coated film. The UMo kernels mostly lost their spherical shape for faceted and elongated shapes whereas three types of film degradations were identified including cracks, chippings and delamination.

Published
2022
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3. Morphological characterization of the fresh ZrN coated UMo powders used in EMPIrE irradiation experiment: A practical approach

Author

François Housaer, Jérôme Allenou, Matthieu Touzin, Abdellatif M. Yacout, Olivier Tougait, Hervé Palancher, F Vanni, Bertrand Stepnik, franck béclin, Ann Leenaers, FRAMATOME, Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Centre d'Etude de l'Energie Nucléaire (SCK-CEN), Argonne National Laboratory [Lemont] (ANL), Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centrale Lille Institut (CLIL), and Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille

Subjects
Nuclear and High Energy Physics, Materials science, Diffusion barrier, Metallurgy, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, engineering.material, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, 010305 fluids & plasmas, Atomic layer deposition, Nuclear Energy and Engineering, Coating, Physical vapor deposition, 0103 physical sciences, engineering, Surface roughness, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Particle size, 0210 nano-technology, Layer (electronics)
Abstract

The European Mini-Plate Irradiation Experiment (EMPIrE) aims to test the in-pile behavior of various ZrN coated UMo powder batches, produced using different technological processes. UMo(ZrN) particles are typical core-shell systems taking advantages of a dense fissile material, UMo, with a coated ZrN layer acting as a diffusion barrier. The U-7Mo kernels were produced by centrifugal or rotating electrode atomization processes and the ZrN coating was performed by physical vapor deposition or atomic layer deposition processes. A total of ten batches of UMo(ZrN) powders were examined in the as-obtained state, i.e prior to fuel-plate fabrication and before in-pile irradiation. The present investigation gives a characterization of each powder batch mainly in terms of morphological and microstructural features carried out by means of SEM-EDS, LOM, EPMA, AFM and TEM analyses. Digital image processing using ImageJ software was employed to determine several particle size (major axis, minor axis, Feret’s diameters, and equivalent diameter) and shape (aspect ratio, circularity, convexity and concavity) parameters as well as the ZrN deposited layer thickness. The quality of the ZrN layer was examined in terms of surface roughness, grain structure and aggregated habits. Our characterization results draw a detailed portrait of the UMo(ZrN) powders selected for the EMPIrE experiment and allow a classification of the powder batches which is presented as radar chart (Kiviat diagram).

Published
2020
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4. A new SPH density formulation for 3D free-surface flows

Author

Bertrand Stepnik, S. Adami, Olivier Bonnefoy, Sandra Geara, Jérôme Allenou, Sylvain Martin, and Winfried Petry

Subjects
Physics, General Computer Science, Volume (thermodynamics), Free surface, General Engineering, Particle, Mechanics, Representation (mathematics), Curvature, Instability, Square (algebra), Domain (mathematical analysis)
Abstract

In this paper, a new density formulation for free surface simulations using SPH is presented. This new approach is applicable to surface-tension driven free surface flows with strong topological changes. The density is corrected for each particle by analytically calculating the missing volume of the support domain. This calculation depends on two parameters: the local curvature and the distance of each particle to the free surface. This method was validated and compared with the density evolution method for two test cases: the square droplet and the Rayleigh-Plateau instability. It shows more stable results and a better representation of the free surface.

Published
2022
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5. Analysis of the interaction products in U(Mo,X)/Al and U(Mo,X)/Al(Si) diffusion couples, with X=Cr, Ti, Zr

Author

Rémi Tucoulou, Anne Bonnin, Jérôme Allenou, H. Palancher, H. El Bekkachi, Olivier Tougait, Xavière Iltis, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), CEA Cadarache, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département d'Etudes des Combustibles (DEC), 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), European Synchrotron Radiation Facility (ESRF), Institut des Sciences Chimiques de Rennes ( ISCR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Ecole Nationale Supérieure de Chimie de Rennes-Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Département d'Etudes des Combustibles ( DEC ), European Synchrotron Radiation Facility ( ESRF ), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Materials science, Silicon, XRD, Diffusion, MTR, Alloy, Analytical chemistry, zirconium, interaction, chemistry.chemical_element, 02 engineering and technology, engineering.material, 01 natural sciences, uranium, Chromium, molybdenum, Aluminium, 0103 physical sciences, General Materials Science, titanium, 010302 applied physics, Zirconium, diffusion couple, aluminium, Metallurgy, silicon, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Nuclear Energy and Engineering, chemistry, Molybdenum, [ CHIM.MATE ] Chemical Sciences/Material chemistry, engineering, chromium, 0210 nano-technology, fuel, Titanium
Abstract

International audience; In the framework of the development of a low 235U enriched nuclear fuel for material testing reactors, γ-U(Mo)/Al based materials are considered as the most interesting prospect. In the process to optimize their composition, addition to both γ-U(Mo) and Al have been proposed. In this paper, the crystallographic composition of Interaction Layers (ILs) in γ-U(Mo,X)/Al and γ-U(Mo,X)/AlSi7 diffusion couples, with X = Cr, Ti, Zr, heat-treated at 600 °C for 2 h, were studied by micro-X-ray diffraction (μ-XRD). When compared to the U(Mo)/Al and U(Mo)/Al(Si) reference systems, all investigated systems involving either Al or Al(Si) as counterparts show interaction products composed of similar phases and related sequences of phase formation. Only relative thicknesses of sub-layers and relative fractions of intermediate phases are correlated with the nature of the X element in the γ-U(Mo,X) alloy. More generally this work shows that γ-U(Mo)/Al and γ-U(Mo)/Al(Si) ILs are now robustly described down to the micrometer scale.

Published
2014
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6. About molybdenum behaviour during U(Mo)/Al(Si) interaction processes

Author

Olivier Tougait, H. Palancher, Jérôme Allenou, B. Verhaeghe, Rémi Tucoulou, Anne Bonnin, Xavière Iltis, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Département d'Etudes des Combustibles (DEC), 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), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Nuclear and High Energy Physics, Materials science, Diffusion, Alloy, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, engineering.material, 021001 nanoscience & nanotechnology, 01 natural sciences, Crystallography, Nuclear Energy and Engineering, chemistry, Molybdenum, Phase (matter), 0103 physical sciences, Scanning transmission electron microscopy, engineering, General Materials Science, Destabilisation, 0210 nano-technology, Spectroscopy, Ternary operation
Abstract

U(Mo)/Al(Si) diffusion couples are studied to provide a better understanding of the interaction processes between the U(Mo) fuel and the Al(Si) matrix and, more specifically, to determine the molybdenum behaviour in the interaction product, close to the U(Mo) alloy. Micro-computed tomography and micro-X-ray diffraction measurements in transmission mode, coupled with scanning transmission electron microscopy and energy dispersive X-ray spectroscopy analysis show that molybdenum is present in the interaction layer, close to the U(Mo) interface, in an U 4 Mo(Mo x Si 1− x )Si 2 ternary intermediate phase, mixed with the U 3 Si 5 phase. The formation of this Mo-containing phase is accompanied by a Mo depletion process, in the underlying U(Mo) alloy, this depletion leading to a γ-U(Mo) phase local destabilisation. A strong correlation between the Si and the Mo behaviours, in the U(Mo)/Al(Si) system, is thus evidenced.

Published
2013
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7. Magnesiothermic Reduction Process Applied to the Powder Production of U(Mo) Fissile Particles

Author

Marie-Christine Anselmet, Henri Noël, Xavière Iltis, François Charollais, Olivier Tougait, Mathieu Pasturel, Guillaume Champion, Jérôme Allenou, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Service Plutonium Uranium et Actinides mineurs (SPUA), Département d'Etudes des Combustibles (DEC), 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), CEA Cadarache, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes ( ISCR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Ecole Nationale Supérieure de Chimie de Rennes-Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ), Service Plutonium Uranium et Actinides mineurs ( SPUA ), and Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )

Subjects
Equiaxed crystals, magnesiothermic, Materials science, reduction process, Uranium dioxide, chemistry.chemical_element, Crucible, Kroll process, 02 engineering and technology, 01 natural sciences, 010305 fluids & plasmas, chemistry.chemical_compound, [ CHIM.OTHE ] Chemical Sciences/Other, 0103 physical sciences, powder production, General Materials Science, Porosity, fissile particle, uranium molybdenum, Magnesium, Metallurgy, uranium molybdenum fissile particle magnesiothermic redn process powder prodn, 021001 nanoscience & nanotechnology, Condensed Matter Physics, chemistry, Volume fraction, Grain boundary, 0210 nano-technology, [CHIM.OTHE]Chemical Sciences/Other
Abstract

International audience; Uranium-molybdenum alloy powders are obtained by a new synthetic route deriving from the Kroll process which avoids a "melting-solidification" step. This alternative process consists in the redn. of uranium dioxide by magnesium in presence of Mo in a sealed Mo crucible heated at temps. ranging from 750 to 1100 °C for dwell periods ranging from 12 to 48 h. An appropriate quenching allows the retention of the high temp. bcc-form $\gamma$-U(Mo). The side products are easily removed by a soaking into a dild. hydrochloric acid soln. under sonication. The agglomerates have a typical size in the range 10-200 μm, with an irregular shape. They display even at the periphery equiaxed grains with homogeneous distribution of Mo. Small closed porosity, which seems to be preferentially located at the grain boundaries corresponds to roughly 2% of the vol. fraction. [on SciFinder(R)]

Published
2013
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8. Interdiffusion behaviors in doped molybdenum uranium and aluminum or aluminum silicon dispersion fuels: Effects of the microstructure

Author

Xavière Iltis, M.C. Anselmet, Jérôme Allenou, Olivier Tougait, Mathieu Pasturel, F. Charollais, P. Lemoine, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Service Plutonium Uranium et Actinides mineurs (SPUA), Département d'Etudes des Combustibles (DEC), 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), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Materials science, Silicon, Alloy, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, engineering.material, 01 natural sciences, 010305 fluids & plasmas, chemistry.chemical_compound, Aluminium, 0103 physical sciences, Silicide, General Materials Science, Doping, Metallurgy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Microstructure, Nuclear Energy and Engineering, chemistry, Molybdenum, engineering, 0210 nano-technology, Ternary operation
Abstract

International audience; Si addition to Al is considered as a promising route to reduce (U,Mo)-Al interaction kinetics, due to its accumulation in the interaction layer, yielding the formation of silicide phases. The (U,Mo) alloy microstructure, and especially its homogenization state, could play a role on this accumulation process. The addition of a third element in γ(U,Mo) could also influence diffusion mechanisms of Al and Si. These two parameters were studied by means of diffusion couple experiments by joining γU based alloys with Al and (Al,Si) alloy. Chemical elements X added into γ(U,Mo) were thoroughly chosen on the following criteria: (i) the potential solubility of the alloying element into the γ(U,Mo) matrix, (ii) its capability to form the ternary aluminides based on the CeCr2Al20 and Ho6Mo4Al43 - types, and (iii) the feasibility to control the microstructure of the alloys. On this basis, a test matrix is defined. It concerns γ(U80,Mo15,X5) alloys (in at.%) with X = Y, Cu, Zr, Ti or Cr. These alloys were homogenized and coupled with Al or (Al,Si) alloy. Results evidenced, first, the importance of the state of homogenization of the γ(U,Mo) binary alloy on interaction processes with (Al,Si) alloy, and the benefit on the diffusion of Si through the interaction layer, as observed on the elementary concentration profiles, when the third element X has some solubility into γ(U,Mo) alloy.

Published
2011
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9. U-Mo/Al-Si interaction: Influence of Si concentration

Author

Ph. Martin, M. Cornen, M.C. Anselmet, Olivier Tougait, Jérôme Allenou, Xavière Iltis, Rémi Tucoulou, Hervé Palancher, C. Valot, F. Charollais, P. Lemoine, Eleonore Welcomme, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut des Sciences Chimiques de Rennes (ISCR), Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Rennes-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES), European Synchrotron Radiation Facility (ESRF), C. Jarousse and M. Grasse, from AREVA-CERCA (Romans, France) are gratefully acknowledged for supplying the U–Mo samples used in this study. J. Miragaya and L. Silvestre (CEA/Cadarache) are warmly thanked for diffusion couples preparation., Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Materials science, Silicon, Diffusion, Alloy, Analytical chemistry, Energy-dispersive X-ray spectroscopy, Mineralogy, chemistry.chemical_element, 02 engineering and technology, engineering.material, 7. Clean energy, 01 natural sciences, 0103 physical sciences, General Materials Science, Irradiation, 010302 applied physics, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Microstructure, Nuclear Energy and Engineering, chemistry, engineering, 0210 nano-technology, Literature survey, Mass fraction
Abstract

International audience; Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 °C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si)3 + UMo2Al20, when the other sub-layer (close to U-Mo) is silicon free and made of UAl3 and U6Mo4Al43. For Si weight concentrations above 5 wt.%, the Si-rich part becomes U3(Si, Al)5 + U(Al, Si)3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si)3 + UMo2Al20. On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).

Published
2010
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