33 research outputs found
Etude de la synthĂšse et de la caractĂ©risation de microsphĂšres dâoxydes dâactinides et de leur mise en Ćuvre pour la fabrication de matĂ©riaux cĂ©ramique Ă microstructures contrĂŽlĂ©es
Responsable CEA : Delahaye, ThibaudDirecteur universitaire : Ayral, AndrĂ©National audienceLa fermeture du cycle Ă©lectronuclĂ©aire est aujourdâhui une des volontĂ©s françaises dans laquellesâinscrit le recyclage des dĂ©chets nuclĂ©aires en sortie de rĂ©acteur. Contributeur majeur Ă leurradiotoxicitĂ©, le plutonium (Pu) est valorisĂ© par la production de combustible MOx oĂč il est mĂ©langĂ©Ă de lâuranium (U) appauvri, pour ĂȘtre Ă nouveau irradiĂ©. Aujourdâhui coulĂ©s dans des verres etstockĂ©s dans des sites dĂ©diĂ©s, deux autres types de dĂ©chets restent Ă gĂ©rer : les produits defission (PF), Ă demi-vie courte, et les actinides mineurs (AM) qui sont, malgrĂ© leur faible teneur(0,7% at. du combustible usĂ©), les principaux contributeurs Ă la radiotoxicitĂ© et Ă la thermicitĂ© desdĂ©chets sur le long terme, aprĂšs recyclage du Pu. Les AM sont reprĂ©sentĂ©s par les troisradioĂ©lĂ©ments suivants : lâamĂ©ricium (Am), le neptunium (Np) et le curium (Cm).La nĂ©cessitĂ© dâune gestion Ă long terme des AM a Ă©tĂ© dĂ©finie par la loi Bataille de 1991, complĂ©tĂ©een 2006, qui dĂ©finit les grands axes de recherche dans ce domaine avec, dâune part lâĂ©tude dustockage en grande profondeur, et dâautre part la dĂ©monstration de la faisabilitĂ© technique de lasĂ©paration et de la transmutation des AM en rĂ©acteurs Ă neutrons rapides (RNR). Dans ce derniercas, deux modes de transmutation sont couramment considĂ©rĂ©s : la transmutation homogĂšne pourlaquelle les AM sont directement associĂ©s au combustible en quantitĂ©s limitĂ©s (<3%) afin de nepas modifier la neutronique du cĆur et la transmutation hĂ©tĂ©rogĂšne pour laquelle des composĂ©sdĂ©diĂ©s de type (U,AM)O (10 < AM < 15% at.) sont fabriquĂ©s et placĂ©s en pĂ©riphĂ©rie du cĆur etainsi nommĂ©s couverture chargĂ©es en AM (CCAM). Ce dernier mode constitue la voie derĂ©fĂ©rence. De par son abondance et sa trĂšs grande radiotoxicitĂ©, les Ă©tudes se concentrentactuellement sur la transmutation hĂ©tĂ©rogĂšne de lâAm avec la fabrication et lâirradiation de pastillesdâUAmO
Experimental and numerical investigations of a soft projectile impact three-point bending (SPITPB) test for adhesion assessment under dynamic loading
The increasing use of digital twins for design in aerospace industry requires the development of validation tests at an intermediate scale prior to full-scale testing. In this paper, a new experimental set-up called Soft Projectile Impact Three-Point Bending (SPITPB) has been investigated by numerical and experimental methods. SPITPB corresponds to an intermediate-scale test representative of a bird strike test, dedicated to the study of the strength of adhesively bonded assemblies. The experimental set-up is detailed in terms of projectile, specimen and boundaries conditions. Three impact velocities leading to three different levels of damage of the adhesive joint are investigated, from intact to highly damaged specimens. A numerical simulation of the SPITPB is achieved with the commercial code LS-DYNAÂź. A Smooth Particle Hydrodynamics model is used to describe the projectile, while the specimen is modelled with a finite element approach. The focus is on the structural response of the specimen and the damage of the adhesive joint. Numerical simulation results demonstrate a good correlation with the experimental data in terms of structural displacement, local strain and post-mortem crack length observations. The dynamic behaviour of the adhesive and the failure model are finally validated as a result of this correlation
Observation of dislocation in some binary and ternary copper base alloys of F.C.C. structure
In this communication an attempt has been made to study by transmission electron microscopy, the various dislocations that were observed in some binary and ternary alloys of copper-zinc and aluminium after various degrees of rolling. Stacking fault nodes and fringes were frequently observed for all the alloys except for extra pure copper. The shape of the stacking fault nodes found gradually to decrease with increase in zinc and decrease in aluminium content. (Mr. S.K. Bose, Scientist, National Metallurgical Laboratory, Jamshedpur); Melle M.F. Denanot and J. Caisso; Laboratorie Metallurgie de physique, Faculte des Sciences Universite de Poitiers, France
Synthesis of ceramic-metal hybrid porous materials for catalysis application using the weak acid resin process
SSCI-VIDE+CARE+ACV:PVEInternational audienceNon
Synthesis of ceramic-metal hybrid porous materials for catalysis application using the weak acid resin process
SSCI-VIDE+CARE+ACV:PVEInternational audienceNon
Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uraniumâamericium mixed oxides
International audienc
Melting behaviour of americium-doped uranium dioxide
International audienc
Innovative oxide precursor synthesis dedicated to dustless process for minor actinide pellet fabrication
International audienc