An extensive irradiation program has been devoted by CEA to the assessment of transmutation using... more An extensive irradiation program has been devoted by CEA to the assessment of transmutation using minor actinide bearing inert support targets. A first irradiation experiment was performed in the fast neutron reactor Phenix, in parallel to other experiments carried out in the HFR and Siloe reactors, in order to assess the behavior under fast neutron flux of various materials intended as inert support matrix for transmutation targets. This experiment, which included the two steps MATINA 1 and MATINA 1A, was completed in 2004 and underwent complete post irradiation examinations (PIE) , whose results are presented in this paper. All the pure inert materials showed a satisfactory behavior under fast neutrons except Al{sub 2}O{sub 3} - which exhibits a swelling close to 11 vol. % after irradiation. In presence of UO{sub 2} fissile particles, MgAl{sub 2}O{sub 4} proved to be more stable in term of swelling as inert support than MgO and Al{sub 2}O{sub 3} matrices, under the same irradiatio...
International audienceThe thermal conductivity is an important parameter for the assessment of th... more International audienceThe thermal conductivity is an important parameter for the assessment of the FBR fuel thermal behavior during irradiation. In this study, the effect of burn-up on the thermal conductivity of FBR MOX fuel is investigated experimentallly. The thermal diffuvitiy of FBR fuel with a burn-up of 13 at% was measured by the laser flash technique and the thermal conductivity was deduced. It is shown that the thermal conductivity is higher than could be predicted with correlations issued from LWR UO2 and MOX results. This effect is interpreted as being due to the diffusion of fission products out of the fuel matrix, leading to the formation of the JOG
Electron probe microanalyses are very powerful techniques used in materials sciences, even on top... more Electron probe microanalyses are very powerful techniques used in materials sciences, even on topics concerning nuclear materials. But such characterizations of radioactive materials remain a challenge because of the necessity to adapt the tools to this highly-constrained environment. In this article, different aspects of these challenges are described, from the design of nuclearized devices set up in hot cell facilities, to examples showing the accuracy of EPMA analyses, or the complementarity with other characterizations tools, to conclude on nuclear material behavior.
The present study describes the in-situ electrochemical modifications which affect irradiated PWR... more The present study describes the in-situ electrochemical modifications which affect irradiated PWR UO 2 fuels in the course of a power ramp, by means of in-situ oxido-reduction indicators such as chromium or neo-formed chemical phases. It is shown that sub-stoichiometric irradiated fuels under temperature gradient such as that occurring during high power transients are submitted to strong oxido-reduction perturbations, owing to radial migration of oxygen from the hot center to the cold periphery of the pellet. The oxygen redistribution, similar to that encountered in Sodium Fast Reactors fuels, induces a massive reduction/precipitation of the fission products Mo, Ru, Tc and Cr (if present) in the high temperature pellet section and the formation of highly oxidized neo-formed grey phases of U 4 O 9 type in its cold section, of lower temperature. To our knowledge, it is the first time that such a phenomenon, likely to greatly impact the corrosive fission gas release, is experimentally attested for PWR fuels. The parameters governing the oxidation states of UO 2 fuels under power ramps are finally debated from a cross-analysis of our results and other published information. The potential chemical benefits brought by oxido-reductive additives in UO 2 fuel such as chromium oxide, in connection with their oxygen buffering properties, are discussed.
... ever found in this zone [5]. Comparatively to the original crude oil PAH concentrations, impo... more ... ever found in this zone [5]. Comparatively to the original crude oil PAH concentrations, important decreases are observed for sample H1 (the most contaminated sample): about 30 % less forFlr to B(k) Flr and 90 % for ... MN, DMN, MFI and DMFl are severally altered in sample H1. ...
A new simulation method was developed for studying the ageing of polymer modified bitumens (PmBs)... more A new simulation method was developed for studying the ageing of polymer modified bitumens (PmBs). An ageing cell specially was designed and fitted to a Fourier transform infrared (FTIR) microscope to continually and directly study the oxidation of PmB by FTIR microscopy imaging. The method was applied to a styrene-butadiene-styrene (SBS) modified bitumen. This PmB features a two-phase structure with polymer-rich areas along with polymer poor regions. Changes in the chemical properties were observed during ageing. This structural and functional evolution was monitored in both phases simultaneously to determine the kinetics of appearance and disappearance of chemical species. The method also allows the study of ageing by kinetic mapping. Moreover, this methodology allows the analysis of PmB samples without destroying their internal equilibrium. This paper presents some of the possibilities of this new ageing cell.
The purpose of the ECRIX-H experiment is to study the behaviour of a composite ceramic target mad... more The purpose of the ECRIX-H experiment is to study the behaviour of a composite ceramic target made of AmO1.62 microdispersed in an MgO matrix irradiated for 318 EFPD in the Phenix sodium-cooled fast reactor (SFR), in a specific carrier sub-assembly equipped with annular blocks of CaHx acting as a neutron moderator. Results indicate that magnesia-based inert matrix targets display satisfactory
ABSTRACT The ECRIX-H irradiation experiment studied the behaviour of pellets containing americium... more ABSTRACT The ECRIX-H irradiation experiment studied the behaviour of pellets containing americium dispersed in MgO. The purpose of the irradiation was to demonstrate the capacity of magnesia to provide an efficient support matrix. After fabrication, the sintered pellets contained 16.65wt.% of Am microdispersed in the inert matrix. The ECRIX-H pellets were irradiated under a locally moderated neutron flux in the Phénix sodium-cooled fast reactor (SFR) for 318 Effective Full Power Days (EFPD). Post-test calculations indicated that the fission and transmutation rates of americium at the maximum flux plane reached 33.9% and 92.6% respectively at the end of the irradiation phase. The results of the post-irradiation examinations – both non-destructive and destructive – are discussed in this paper. These results indicate a satisfactory behaviour of the MgO matrix. Particularly, a moderate swelling occurs in the pellets under irradiation even with significant quantities of helium generated and at high transmutation rate.
Within the context of reprocessing irradiated nuclear fuel from nuclear power reactors, fuel rods... more Within the context of reprocessing irradiated nuclear fuel from nuclear power reactors, fuel rods are cut into pieces for dissolution in fuel reprocessing plants so as to separate the fuel from the cladding material. The structural waste coming from claddingcalled ''hulls''-is conditioned in specifically-designed matrices for disposal. Standard characterisations of these hulls, such as neutron emission measurements or gamma spectrometry analyses, have already been performed on such samples. This paper describes a series of local characterisations that were performed on these hulls using various microanalysis techniques. Three techniques were used: a scanning electron microscope equipped with a wavelength dispersive X-ray detector, an electron probe microanalyser, and a secondary ion mass spectrometer. This paper describes the analytical methodology used to better understand the physicochemical behaviour of the different radioelements contaminating the hulls.
In order to reduce the uncertainties concerning Source Term assessment under Light Water Reactor ... more In order to reduce the uncertainties concerning Source Term assessment under Light Water Reactor (LWR) severe accident conditions, 4 VERDON tests were recently performed. They have been defined in the framework of the International Source Term Program and carried out at CEA Cadarache, in the LECA-STAR facility. Among these 4 VERDON tests, VERDON-1 test was devoted to high burn-up UO 2 fuel behavior and FP release under H 2 reducing conditions at very high temperature. This test was performed with the Release Circuit, which is devoted to the precise characterization of the FP release, in terms of FP release kinetics and fission products (FPs) released fraction. The main components of the circuits are a furnace heating the fuel sample, a filter trapping the emitted aerosols and gamma spectrometry detectors for online and post-test measurements. VERDON-1 test was conducted up to about 2600°C without reaching global fuel relocation, allowing thereby post-test micro-analyses. After a brief description of the fuel sample nature and the experimental setup , we present the progress of the experimental sequence and the associated gamma spectrometry measurements. We then focus on the major results of the VERDON-1 tests regarding the fuel global behavior. These results are obtained by two complementary techniques. First, the fuel sight gamma station can be used either on-line to detect fuel relocation or just after the test, as a longitudinal bench, to get preliminary information on the global shape of the fuel sample inside the furnace. Secondly, these information are completed by post-test examinations performed on the fuel sample after extraction from the furnace. Complete qualitative and quantitative characterizations, including EPMA and SEM analysis, were performed for the first time at the CEA Cadarache on a sample that has been submitted to such severe accident conditions. These results show an advanced state of sample degradation, with locally previously molten areas, meaning that fuel global relocation was imminent by the end of thermal-hydraulic sequence. The relocation temperature is compared to that of previous VERCORS tests and discussed regarding the atmosphere of the test and possible UO 2-ZrO 2 interaction.
When submitted to heating tests reaching 1200 °C, pellet long fuel samples generally exhibit crac... more When submitted to heating tests reaching 1200 °C, pellet long fuel samples generally exhibit cracking after the test, nonetheless, the fuel keeps its original shape and most of the fragments remain inside the cladding section [1]. However, after having been submitted to a 1200 °C, 20 °C/s, heating test with a surrounding pressure close to 0.1 MPa, in the Merarg LECA-STAR CEA device, a UO$_2$ section, with a local average burn-up of 83 GWd/t$_U$, was found fragmented, with most of the fragments outside of the cladding and in the crucible used for the test. These fragments exhibited a wide range of sizes. Detailed examinations on a sibling sample had been previously conducted. They are partly reported in [2]. Using these previous results as a reference for the fuel microstructure and composition along the pellet radius, a detailed examination of thirty three of these fragments was conducted using the EPMA. The purpose of these detailed examinations was to determine the radial origin o...
When UO 2 and (U,Pu)O 2 fuels locally reach high burn-up, a major change in the microstructure ta... more When UO 2 and (U,Pu)O 2 fuels locally reach high burn-up, a major change in the microstructure takes place. The initial grains are replaced by thousands of much smaller grains, fission gases form micrometric bubbles and metallic fission products form precipitates. This occurs typically at the rim of the pellets and in heterogeneous MOX fuel Pu rich agglomerates. The high burn-up at the rim of the pellets is due to a high capture of epithermal neutrons by 238 U leading locally to a higher concentration of fissile Pu than in the rest of the pellet. In the heterogeneous MOX fuels, this rim effect is also active, but most of the high burn-up structure (HBS) formation is linked to the high local concentration of fissile Pu in the Pu agglomerates. This Pu distribution leads to sharp borders between HBS and non-HBS areas (Fig.1).
The formation of gas bubbles is a key issue for nuclear fuel behaviour. The first measurements of... more The formation of gas bubbles is a key issue for nuclear fuel behaviour. The first measurements of xenon during a depth profile in irradiated nuclear fuel evidenced some peaks over a non-zero baseline. In comparison with EPMA mappings of xenon and SEM image of the sputtered surface, it is proven that the peaks correspond to bubbles while the baseline corresponds to xenon included in the UO 2 matrix.
A UO 2 fuel with a heterogeneous distribution of 235 U was irradiated up to a high burn-up in the... more A UO 2 fuel with a heterogeneous distribution of 235 U was irradiated up to a high burn-up in the Halden Boiling Water Reactor (HBWR). The last 100 days of irradiation were performed with an increased level of linear power. The effect of the heterogeneous fissile isotope distribution on the formation of the HBS was studied free of the possible influence of Pu which exists in heterogeneous MOX fuels. The HBS formed in 235 U-rich agglomerates and its main characteristics were those of the HBS formed in Pu-rich agglomerates of heterogeneous MOX fuels. The maximum local contents of Nd and Xe before HBS formation were studied in this fuel. In addition to a Pu effect that promotes the HBS phenomenon, comparison with previous results for heterogeneous MOX fuels showed that the local fission product concentration was not the only parameter to take into consideration. It appears that the local actinide content depletion by fission and/or the energy locally deposited through electronic interactions in the fission fragment recoils also have an effect on the HBS formation threshold. Moreover, a major release of fission gases from the peripheral 235 U-rich agglomerates of HBS bubbles and a Cs radial movement are also evidenced in this heterogeneous UO 2. Cs deposits on the peripheral grain boundaries, including the HBS grain boundaries, reveal the release paths.
The purpose of this study was to evaluate reservoir continuities and geochemical evolution of oil... more The purpose of this study was to evaluate reservoir continuities and geochemical evolution of oils from individual reservoirs by using gas chromatography (GC) fingerprints method and to compare the results with those obtained from Fourier transform infra red (FTIR) and synchronous ultra violet fluorescence (SUVF) spectroscopy techniques. Six crude oils which belong to different levels of exploitation were selected from Alam El Bueib (AEB) oil field (Western Desert, Egypt). The samples studied belong to three different reservoir units in different wells.The results show that the all-independent techniques provide results in good agreement and that the oils characteristics and their evolution in the reservoir can be described similarly by fingerprints GC, FTIR and SUVF spectroscopy. The FTIR and SUVF spectroscopy techniques therefore constitute a rapid and non-expensive alternative for reservoir organic geochemistry studies.
Sixth International RILEM Symposium on Performance Testing and Evaluation of Bituminous Materials, 2003
This paper presents the results of a study of the ageing of different polymer modified bitumens (... more This paper presents the results of a study of the ageing of different polymer modified bitumens (PmBs) containing either saturated plastomers or unsaturated elastomers. Firstly, PmB's ageing throughout its whole service life could be simulated by applying conventional ageing tests, RTFOT, for the mixing process and laying of asphalt concrete, and PAV for in service ageing. Changes in the bitumen properties before and after ageing were thus recorded. Secondly, an ageing cell specially designed to fit the FTIR microscope was developed to study directly and continually the PmB's oxidation by FTIR microscopy imaging. The results obtained by following simultaneously both phases evolution, allow to propose a method to measure changes in PmB's chemical composition. These changes are both bitumen and polymer dependent. Finally, the kinetics study shows that RTFOT and PAV can be simulated in the ageing cell in a quicker way. In conclusion, the design of an ageing cell associated to the FTIR microscope appears to be a very effective tool to observe and chemically study the microstructure of PmBs during ageing. It also gives some insights to evaluate PmB's durability. For the covering abstract see ITRD E117423.
The FUTURIX/FTA experiment has been an international program partly implemented within the frame ... more The FUTURIX/FTA experiment has been an international program partly implemented within the frame of the FP-6 EUROTRANS and FP-7 FAIRFUELS projects, to demonstrate the technical feasibility, with regard to fuel behaviour of transmuting minor actinides in Accelerator Driven Systems and Fast neutron Reactors dedicated to Minor Actinides burning. 8 Am-bearing fuel compositions: 2 metallic, 2 nitride, 2 Mo-CERMET and 2 MgO-CERCER fuel types with Am contents ranging from 0.2 to 1.9 g.cm -3 have been investigated. The MgO-CERCER fuels made of (Pu,Am)O2-x particles dispersed in a magnesia matrix were irradiated in the PHENIX sodium cooled fast reactor up to 6 and 9 at%, at maximum Linear Heat Rates of 80-100W.cm -1 . After a recap of the MgO-CERCER fuel pins features as well as the irradiation conditions, the paper gives an overview of the Post Irradiation Examination results gained within the FAIRFUELS European project, on these 2 ADS type fuels. The Post Irradiation Examinations have been...
An extensive irradiation program has been devoted by CEA to the assessment of transmutation using... more An extensive irradiation program has been devoted by CEA to the assessment of transmutation using minor actinide bearing inert support targets. A first irradiation experiment was performed in the fast neutron reactor Phenix, in parallel to other experiments carried out in the HFR and Siloe reactors, in order to assess the behavior under fast neutron flux of various materials intended as inert support matrix for transmutation targets. This experiment, which included the two steps MATINA 1 and MATINA 1A, was completed in 2004 and underwent complete post irradiation examinations (PIE) , whose results are presented in this paper. All the pure inert materials showed a satisfactory behavior under fast neutrons except Al{sub 2}O{sub 3} - which exhibits a swelling close to 11 vol. % after irradiation. In presence of UO{sub 2} fissile particles, MgAl{sub 2}O{sub 4} proved to be more stable in term of swelling as inert support than MgO and Al{sub 2}O{sub 3} matrices, under the same irradiatio...
International audienceThe thermal conductivity is an important parameter for the assessment of th... more International audienceThe thermal conductivity is an important parameter for the assessment of the FBR fuel thermal behavior during irradiation. In this study, the effect of burn-up on the thermal conductivity of FBR MOX fuel is investigated experimentallly. The thermal diffuvitiy of FBR fuel with a burn-up of 13 at% was measured by the laser flash technique and the thermal conductivity was deduced. It is shown that the thermal conductivity is higher than could be predicted with correlations issued from LWR UO2 and MOX results. This effect is interpreted as being due to the diffusion of fission products out of the fuel matrix, leading to the formation of the JOG
Electron probe microanalyses are very powerful techniques used in materials sciences, even on top... more Electron probe microanalyses are very powerful techniques used in materials sciences, even on topics concerning nuclear materials. But such characterizations of radioactive materials remain a challenge because of the necessity to adapt the tools to this highly-constrained environment. In this article, different aspects of these challenges are described, from the design of nuclearized devices set up in hot cell facilities, to examples showing the accuracy of EPMA analyses, or the complementarity with other characterizations tools, to conclude on nuclear material behavior.
The present study describes the in-situ electrochemical modifications which affect irradiated PWR... more The present study describes the in-situ electrochemical modifications which affect irradiated PWR UO 2 fuels in the course of a power ramp, by means of in-situ oxido-reduction indicators such as chromium or neo-formed chemical phases. It is shown that sub-stoichiometric irradiated fuels under temperature gradient such as that occurring during high power transients are submitted to strong oxido-reduction perturbations, owing to radial migration of oxygen from the hot center to the cold periphery of the pellet. The oxygen redistribution, similar to that encountered in Sodium Fast Reactors fuels, induces a massive reduction/precipitation of the fission products Mo, Ru, Tc and Cr (if present) in the high temperature pellet section and the formation of highly oxidized neo-formed grey phases of U 4 O 9 type in its cold section, of lower temperature. To our knowledge, it is the first time that such a phenomenon, likely to greatly impact the corrosive fission gas release, is experimentally attested for PWR fuels. The parameters governing the oxidation states of UO 2 fuels under power ramps are finally debated from a cross-analysis of our results and other published information. The potential chemical benefits brought by oxido-reductive additives in UO 2 fuel such as chromium oxide, in connection with their oxygen buffering properties, are discussed.
... ever found in this zone [5]. Comparatively to the original crude oil PAH concentrations, impo... more ... ever found in this zone [5]. Comparatively to the original crude oil PAH concentrations, important decreases are observed for sample H1 (the most contaminated sample): about 30 % less forFlr to B(k) Flr and 90 % for ... MN, DMN, MFI and DMFl are severally altered in sample H1. ...
A new simulation method was developed for studying the ageing of polymer modified bitumens (PmBs)... more A new simulation method was developed for studying the ageing of polymer modified bitumens (PmBs). An ageing cell specially was designed and fitted to a Fourier transform infrared (FTIR) microscope to continually and directly study the oxidation of PmB by FTIR microscopy imaging. The method was applied to a styrene-butadiene-styrene (SBS) modified bitumen. This PmB features a two-phase structure with polymer-rich areas along with polymer poor regions. Changes in the chemical properties were observed during ageing. This structural and functional evolution was monitored in both phases simultaneously to determine the kinetics of appearance and disappearance of chemical species. The method also allows the study of ageing by kinetic mapping. Moreover, this methodology allows the analysis of PmB samples without destroying their internal equilibrium. This paper presents some of the possibilities of this new ageing cell.
The purpose of the ECRIX-H experiment is to study the behaviour of a composite ceramic target mad... more The purpose of the ECRIX-H experiment is to study the behaviour of a composite ceramic target made of AmO1.62 microdispersed in an MgO matrix irradiated for 318 EFPD in the Phenix sodium-cooled fast reactor (SFR), in a specific carrier sub-assembly equipped with annular blocks of CaHx acting as a neutron moderator. Results indicate that magnesia-based inert matrix targets display satisfactory
ABSTRACT The ECRIX-H irradiation experiment studied the behaviour of pellets containing americium... more ABSTRACT The ECRIX-H irradiation experiment studied the behaviour of pellets containing americium dispersed in MgO. The purpose of the irradiation was to demonstrate the capacity of magnesia to provide an efficient support matrix. After fabrication, the sintered pellets contained 16.65wt.% of Am microdispersed in the inert matrix. The ECRIX-H pellets were irradiated under a locally moderated neutron flux in the Phénix sodium-cooled fast reactor (SFR) for 318 Effective Full Power Days (EFPD). Post-test calculations indicated that the fission and transmutation rates of americium at the maximum flux plane reached 33.9% and 92.6% respectively at the end of the irradiation phase. The results of the post-irradiation examinations – both non-destructive and destructive – are discussed in this paper. These results indicate a satisfactory behaviour of the MgO matrix. Particularly, a moderate swelling occurs in the pellets under irradiation even with significant quantities of helium generated and at high transmutation rate.
Within the context of reprocessing irradiated nuclear fuel from nuclear power reactors, fuel rods... more Within the context of reprocessing irradiated nuclear fuel from nuclear power reactors, fuel rods are cut into pieces for dissolution in fuel reprocessing plants so as to separate the fuel from the cladding material. The structural waste coming from claddingcalled ''hulls''-is conditioned in specifically-designed matrices for disposal. Standard characterisations of these hulls, such as neutron emission measurements or gamma spectrometry analyses, have already been performed on such samples. This paper describes a series of local characterisations that were performed on these hulls using various microanalysis techniques. Three techniques were used: a scanning electron microscope equipped with a wavelength dispersive X-ray detector, an electron probe microanalyser, and a secondary ion mass spectrometer. This paper describes the analytical methodology used to better understand the physicochemical behaviour of the different radioelements contaminating the hulls.
In order to reduce the uncertainties concerning Source Term assessment under Light Water Reactor ... more In order to reduce the uncertainties concerning Source Term assessment under Light Water Reactor (LWR) severe accident conditions, 4 VERDON tests were recently performed. They have been defined in the framework of the International Source Term Program and carried out at CEA Cadarache, in the LECA-STAR facility. Among these 4 VERDON tests, VERDON-1 test was devoted to high burn-up UO 2 fuel behavior and FP release under H 2 reducing conditions at very high temperature. This test was performed with the Release Circuit, which is devoted to the precise characterization of the FP release, in terms of FP release kinetics and fission products (FPs) released fraction. The main components of the circuits are a furnace heating the fuel sample, a filter trapping the emitted aerosols and gamma spectrometry detectors for online and post-test measurements. VERDON-1 test was conducted up to about 2600°C without reaching global fuel relocation, allowing thereby post-test micro-analyses. After a brief description of the fuel sample nature and the experimental setup , we present the progress of the experimental sequence and the associated gamma spectrometry measurements. We then focus on the major results of the VERDON-1 tests regarding the fuel global behavior. These results are obtained by two complementary techniques. First, the fuel sight gamma station can be used either on-line to detect fuel relocation or just after the test, as a longitudinal bench, to get preliminary information on the global shape of the fuel sample inside the furnace. Secondly, these information are completed by post-test examinations performed on the fuel sample after extraction from the furnace. Complete qualitative and quantitative characterizations, including EPMA and SEM analysis, were performed for the first time at the CEA Cadarache on a sample that has been submitted to such severe accident conditions. These results show an advanced state of sample degradation, with locally previously molten areas, meaning that fuel global relocation was imminent by the end of thermal-hydraulic sequence. The relocation temperature is compared to that of previous VERCORS tests and discussed regarding the atmosphere of the test and possible UO 2-ZrO 2 interaction.
When submitted to heating tests reaching 1200 °C, pellet long fuel samples generally exhibit crac... more When submitted to heating tests reaching 1200 °C, pellet long fuel samples generally exhibit cracking after the test, nonetheless, the fuel keeps its original shape and most of the fragments remain inside the cladding section [1]. However, after having been submitted to a 1200 °C, 20 °C/s, heating test with a surrounding pressure close to 0.1 MPa, in the Merarg LECA-STAR CEA device, a UO$_2$ section, with a local average burn-up of 83 GWd/t$_U$, was found fragmented, with most of the fragments outside of the cladding and in the crucible used for the test. These fragments exhibited a wide range of sizes. Detailed examinations on a sibling sample had been previously conducted. They are partly reported in [2]. Using these previous results as a reference for the fuel microstructure and composition along the pellet radius, a detailed examination of thirty three of these fragments was conducted using the EPMA. The purpose of these detailed examinations was to determine the radial origin o...
When UO 2 and (U,Pu)O 2 fuels locally reach high burn-up, a major change in the microstructure ta... more When UO 2 and (U,Pu)O 2 fuels locally reach high burn-up, a major change in the microstructure takes place. The initial grains are replaced by thousands of much smaller grains, fission gases form micrometric bubbles and metallic fission products form precipitates. This occurs typically at the rim of the pellets and in heterogeneous MOX fuel Pu rich agglomerates. The high burn-up at the rim of the pellets is due to a high capture of epithermal neutrons by 238 U leading locally to a higher concentration of fissile Pu than in the rest of the pellet. In the heterogeneous MOX fuels, this rim effect is also active, but most of the high burn-up structure (HBS) formation is linked to the high local concentration of fissile Pu in the Pu agglomerates. This Pu distribution leads to sharp borders between HBS and non-HBS areas (Fig.1).
The formation of gas bubbles is a key issue for nuclear fuel behaviour. The first measurements of... more The formation of gas bubbles is a key issue for nuclear fuel behaviour. The first measurements of xenon during a depth profile in irradiated nuclear fuel evidenced some peaks over a non-zero baseline. In comparison with EPMA mappings of xenon and SEM image of the sputtered surface, it is proven that the peaks correspond to bubbles while the baseline corresponds to xenon included in the UO 2 matrix.
A UO 2 fuel with a heterogeneous distribution of 235 U was irradiated up to a high burn-up in the... more A UO 2 fuel with a heterogeneous distribution of 235 U was irradiated up to a high burn-up in the Halden Boiling Water Reactor (HBWR). The last 100 days of irradiation were performed with an increased level of linear power. The effect of the heterogeneous fissile isotope distribution on the formation of the HBS was studied free of the possible influence of Pu which exists in heterogeneous MOX fuels. The HBS formed in 235 U-rich agglomerates and its main characteristics were those of the HBS formed in Pu-rich agglomerates of heterogeneous MOX fuels. The maximum local contents of Nd and Xe before HBS formation were studied in this fuel. In addition to a Pu effect that promotes the HBS phenomenon, comparison with previous results for heterogeneous MOX fuels showed that the local fission product concentration was not the only parameter to take into consideration. It appears that the local actinide content depletion by fission and/or the energy locally deposited through electronic interactions in the fission fragment recoils also have an effect on the HBS formation threshold. Moreover, a major release of fission gases from the peripheral 235 U-rich agglomerates of HBS bubbles and a Cs radial movement are also evidenced in this heterogeneous UO 2. Cs deposits on the peripheral grain boundaries, including the HBS grain boundaries, reveal the release paths.
The purpose of this study was to evaluate reservoir continuities and geochemical evolution of oil... more The purpose of this study was to evaluate reservoir continuities and geochemical evolution of oils from individual reservoirs by using gas chromatography (GC) fingerprints method and to compare the results with those obtained from Fourier transform infra red (FTIR) and synchronous ultra violet fluorescence (SUVF) spectroscopy techniques. Six crude oils which belong to different levels of exploitation were selected from Alam El Bueib (AEB) oil field (Western Desert, Egypt). The samples studied belong to three different reservoir units in different wells.The results show that the all-independent techniques provide results in good agreement and that the oils characteristics and their evolution in the reservoir can be described similarly by fingerprints GC, FTIR and SUVF spectroscopy. The FTIR and SUVF spectroscopy techniques therefore constitute a rapid and non-expensive alternative for reservoir organic geochemistry studies.
Sixth International RILEM Symposium on Performance Testing and Evaluation of Bituminous Materials, 2003
This paper presents the results of a study of the ageing of different polymer modified bitumens (... more This paper presents the results of a study of the ageing of different polymer modified bitumens (PmBs) containing either saturated plastomers or unsaturated elastomers. Firstly, PmB's ageing throughout its whole service life could be simulated by applying conventional ageing tests, RTFOT, for the mixing process and laying of asphalt concrete, and PAV for in service ageing. Changes in the bitumen properties before and after ageing were thus recorded. Secondly, an ageing cell specially designed to fit the FTIR microscope was developed to study directly and continually the PmB's oxidation by FTIR microscopy imaging. The results obtained by following simultaneously both phases evolution, allow to propose a method to measure changes in PmB's chemical composition. These changes are both bitumen and polymer dependent. Finally, the kinetics study shows that RTFOT and PAV can be simulated in the ageing cell in a quicker way. In conclusion, the design of an ageing cell associated to the FTIR microscope appears to be a very effective tool to observe and chemically study the microstructure of PmBs during ageing. It also gives some insights to evaluate PmB's durability. For the covering abstract see ITRD E117423.
The FUTURIX/FTA experiment has been an international program partly implemented within the frame ... more The FUTURIX/FTA experiment has been an international program partly implemented within the frame of the FP-6 EUROTRANS and FP-7 FAIRFUELS projects, to demonstrate the technical feasibility, with regard to fuel behaviour of transmuting minor actinides in Accelerator Driven Systems and Fast neutron Reactors dedicated to Minor Actinides burning. 8 Am-bearing fuel compositions: 2 metallic, 2 nitride, 2 Mo-CERMET and 2 MgO-CERCER fuel types with Am contents ranging from 0.2 to 1.9 g.cm -3 have been investigated. The MgO-CERCER fuels made of (Pu,Am)O2-x particles dispersed in a magnesia matrix were irradiated in the PHENIX sodium cooled fast reactor up to 6 and 9 at%, at maximum Linear Heat Rates of 80-100W.cm -1 . After a recap of the MgO-CERCER fuel pins features as well as the irradiation conditions, the paper gives an overview of the Post Irradiation Examination results gained within the FAIRFUELS European project, on these 2 ADS type fuels. The Post Irradiation Examinations have been...
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Papers by J. Lamontagne