ABSTRACTThe chemical evolution of a clay engineered barrier in a deep repository interacting with... more ABSTRACTThe chemical evolution of a clay engineered barrier in a deep repository interacting with various groundwaters is predicted using the TRIO-EF code supported by additional models tested against experimental data. Main results of this work are related to the long term evolution of the porewater and the buffering effect of the clay barrier in the presence of ion exchange sites and calcite, when exposed to representative granitic groundwaters or more acidic or alkaline waters.
M ost mod elling s found in literature for th e multip le crack ing p rocess of 1 D comp osites c... more M ost mod elling s found in literature for th e multip le crack ing p rocess of 1 D comp osites can be categ orised into th ree d iff erent ap p roach es: a continuous ap p roach (CA) th at assumes an infi nitely long comp osite, and tw o rand om ap p roach es th at consid er comp osites of fi nite leng th. T h e rand om streng th ap p roach (R S A) rests on a sp atial d iscretiz ation of th e comp osite on w h ich a streng th d istribution is ap p lied , w h ereas th e rand om crack ap p roach (R CA) g enerates th e location and th e streng th of each new crack w ith out any d iscretiz ation. T h e fi rst p art of th e p ap er lay s th e mod el and its statistical found ations. T h ey are used to d emonstrate th at th e th ree ap p roach es sh ould p rov id e consistent results. T h e th ree ap p roach es are th en introd uced , w ith sp ecial emp h asis on th e R CA as it is imp lemented for th e fi rst time w ith out any ap p rox imation. F inally , th e results p rov id ed by th e th ree ap p roach es are comp ared , confi rming th eir full consistency .
17 ans après l'accident de Tchernobyl, cette étude propose une reconstitution des dépôts de 137Cs... more 17 ans après l'accident de Tchernobyl, cette étude propose une reconstitution des dépôts de 137Cs dus à cet accident sur l'ensemble du territoire fran ais métropolitain. Cette reconstitution est basée sur la relation entre les dépôts de '"CS et les pluies de la première semaine de mai 1986, validée sur le tiers-est du pays, et sur une modélisation de l'appauvrissement d'est en ouest des masses d'air contaminées. La carte proposée, établie suivant la même méthode géostatistique que celle utilisée par la Commission européenne, est cohérente avec les estimations des dépôts de '37Cs dans les pays d'Europe voisins. I3'Cs deposition mapping in May 1986 over the whole French metropolitan territory. This study intends to reconstruct the I3'Cs deposition over the French territory resulting from the Chernohyl accident, 17 years after its occurrence. This reconstruction b based on the caesium fallout versus atmospheric precipitation relationship during the first week of May 1986, already determined for the Eastern France and the modelling of air masses radioactive load decreaîe toward West. The deposition map is ohtained following the methodology used for the European Commission Atlas. Our map is consistent with estimated deposit over neighhouring countries.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014
Mechanical behaviour of 60 keV He implanted UO 2 polycrystals has been analysed at a macroscopic ... more Mechanical behaviour of 60 keV He implanted UO 2 polycrystals has been analysed at a macroscopic scale using X-ray diffraction techniques (conventional h/h mode and sin 2 w method). The free swelling in the implanted layer has been determined at low damage levels (below 1 dpa) i.e. in a strain regime where the UO 2 crystal structure deforms elastically. The obtained results are in excellent agreement with previous measurements performed at the micrometre (grain) scale using Laue X-ray diffraction. Finally it is shown that evolutions of free swelling with damage level in implanted polycrystals and in self-irradiated (U, 238 Pu)O 2 pellets are similar.
In the framework of the study of long-term storage of the spent nuclear fuel, polycrystalline UO ... more In the framework of the study of long-term storage of the spent nuclear fuel, polycrystalline UO 2 samples have been implanted with He ions. The thin implanted layer, close to the free surface is subjected to elastic stresses which are studied by x-ray diffraction (micro Laue diffraction) and a mechanical modeling. A simple expression of the displacement gradient tensor has been evidenced; it concerns only three terms (ε 3 , ε 4 and ε 5 ) which strongly evolve with considered grain orientations. Finally, we show that results obtained with micro diffraction are in very good agreement with conventional x-ray diffraction measurements done in laboratory at macro scale.
X-ray absorption spectroscopy experiments were performed on a set of xenon implanted uranium diox... more X-ray absorption spectroscopy experiments were performed on a set of xenon implanted uranium dioxide samples. Results indicate that the gas forms highly pressurised inclusions as a result of temperature anneals or an external ion irradiation. Estimated bubble pressures were found to be in the region of 2-5 GPa at low temperature. The consequences of such high pressures developing within intra-granular bubbles in irradiated fuels are discussed. A model is given enabling the computation of the sink strengths of bubbles as a function of the pressure of the rare-gas they contain. The model predicts that for pressure values found in the experiments, fission gas bubbles do not act as sinks for diffusing rare-gas atoms.
. We present here an investigation of the irradiation-induced swelling of SiC using Classical Mo... more . We present here an investigation of the irradiation-induced swelling of SiC using Classical Molecular Dynamics simulations. Heavy ion irradiation has been assumed to affect the material in two steps: (a) creation of local atomic disorder, modeled by the introduction of extended amorphous areas with various sizes and shapes in a crystalline SiC sample at constant volume (b) induced swelling, determined
ABSTRACTThe chemical evolution of a clay engineered barrier in a deep repository interacting with... more ABSTRACTThe chemical evolution of a clay engineered barrier in a deep repository interacting with various groundwaters is predicted using the TRIO-EF code supported by additional models tested against experimental data. Main results of this work are related to the long term evolution of the porewater and the buffering effect of the clay barrier in the presence of ion exchange sites and calcite, when exposed to representative granitic groundwaters or more acidic or alkaline waters.
M ost mod elling s found in literature for th e multip le crack ing p rocess of 1 D comp osites c... more M ost mod elling s found in literature for th e multip le crack ing p rocess of 1 D comp osites can be categ orised into th ree d iff erent ap p roach es: a continuous ap p roach (CA) th at assumes an infi nitely long comp osite, and tw o rand om ap p roach es th at consid er comp osites of fi nite leng th. T h e rand om streng th ap p roach (R S A) rests on a sp atial d iscretiz ation of th e comp osite on w h ich a streng th d istribution is ap p lied , w h ereas th e rand om crack ap p roach (R CA) g enerates th e location and th e streng th of each new crack w ith out any d iscretiz ation. T h e fi rst p art of th e p ap er lay s th e mod el and its statistical found ations. T h ey are used to d emonstrate th at th e th ree ap p roach es sh ould p rov id e consistent results. T h e th ree ap p roach es are th en introd uced , w ith sp ecial emp h asis on th e R CA as it is imp lemented for th e fi rst time w ith out any ap p rox imation. F inally , th e results p rov id ed by th e th ree ap p roach es are comp ared , confi rming th eir full consistency .
17 ans après l'accident de Tchernobyl, cette étude propose une reconstitution des dépôts de 137Cs... more 17 ans après l'accident de Tchernobyl, cette étude propose une reconstitution des dépôts de 137Cs dus à cet accident sur l'ensemble du territoire fran ais métropolitain. Cette reconstitution est basée sur la relation entre les dépôts de '"CS et les pluies de la première semaine de mai 1986, validée sur le tiers-est du pays, et sur une modélisation de l'appauvrissement d'est en ouest des masses d'air contaminées. La carte proposée, établie suivant la même méthode géostatistique que celle utilisée par la Commission européenne, est cohérente avec les estimations des dépôts de '37Cs dans les pays d'Europe voisins. I3'Cs deposition mapping in May 1986 over the whole French metropolitan territory. This study intends to reconstruct the I3'Cs deposition over the French territory resulting from the Chernohyl accident, 17 years after its occurrence. This reconstruction b based on the caesium fallout versus atmospheric precipitation relationship during the first week of May 1986, already determined for the Eastern France and the modelling of air masses radioactive load decreaîe toward West. The deposition map is ohtained following the methodology used for the European Commission Atlas. Our map is consistent with estimated deposit over neighhouring countries.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014
Mechanical behaviour of 60 keV He implanted UO 2 polycrystals has been analysed at a macroscopic ... more Mechanical behaviour of 60 keV He implanted UO 2 polycrystals has been analysed at a macroscopic scale using X-ray diffraction techniques (conventional h/h mode and sin 2 w method). The free swelling in the implanted layer has been determined at low damage levels (below 1 dpa) i.e. in a strain regime where the UO 2 crystal structure deforms elastically. The obtained results are in excellent agreement with previous measurements performed at the micrometre (grain) scale using Laue X-ray diffraction. Finally it is shown that evolutions of free swelling with damage level in implanted polycrystals and in self-irradiated (U, 238 Pu)O 2 pellets are similar.
In the framework of the study of long-term storage of the spent nuclear fuel, polycrystalline UO ... more In the framework of the study of long-term storage of the spent nuclear fuel, polycrystalline UO 2 samples have been implanted with He ions. The thin implanted layer, close to the free surface is subjected to elastic stresses which are studied by x-ray diffraction (micro Laue diffraction) and a mechanical modeling. A simple expression of the displacement gradient tensor has been evidenced; it concerns only three terms (ε 3 , ε 4 and ε 5 ) which strongly evolve with considered grain orientations. Finally, we show that results obtained with micro diffraction are in very good agreement with conventional x-ray diffraction measurements done in laboratory at macro scale.
X-ray absorption spectroscopy experiments were performed on a set of xenon implanted uranium diox... more X-ray absorption spectroscopy experiments were performed on a set of xenon implanted uranium dioxide samples. Results indicate that the gas forms highly pressurised inclusions as a result of temperature anneals or an external ion irradiation. Estimated bubble pressures were found to be in the region of 2-5 GPa at low temperature. The consequences of such high pressures developing within intra-granular bubbles in irradiated fuels are discussed. A model is given enabling the computation of the sink strengths of bubbles as a function of the pressure of the rare-gas they contain. The model predicts that for pressure values found in the experiments, fission gas bubbles do not act as sinks for diffusing rare-gas atoms.
. We present here an investigation of the irradiation-induced swelling of SiC using Classical Mo... more . We present here an investigation of the irradiation-induced swelling of SiC using Classical Molecular Dynamics simulations. Heavy ion irradiation has been assumed to affect the material in two steps: (a) creation of local atomic disorder, modeled by the introduction of extended amorphous areas with various sizes and shapes in a crystalline SiC sample at constant volume (b) induced swelling, determined
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