Procédé de stockage et de libération d’énergie thermique par voie thermochimique

L’invention se rapporte à un procédé de stockage et de libération d’énergie thermique par voie thermochimique au moyen d’un composé sous forme solide de formule AOxBy.zH2O, où : A est un élément choisi parmi l’uranium (U) et le thorium (Th) ; est l’élément oxygène ; B est un anion ou un oxoanion ; x est un nombre compris entre 0 et 4 ; y est un nombre compris entre 0 et 2 ; z est un nombre supérieur à 0 et inférieur à 10, étant entendu que l’un au moins de x et y est différent de 0 et que le composé de formule Th(SO4)2.xH2O est exclu

Estimation of the vitrified canister production for a PWR fleet with the CLASS code

This article presents an assessment of fuel cycle parameter impact on waste production through the prism of vitrified container and minor actinide masses, using a scenario simulated with the CLASS code. The number of canister introduces a new focus on waste production estimation for a nuclear fleet, as it helps to set the repository size for deep geological disposal of high level waste. To evaluate the number of canisters, dedicated developments to model a simplified waste vitrification unit in the CLASS package are presented. It relies on artificial neural network estimations of decay heat, α radiation and mass content, for different material flow coming from reprocessing and sent to vitrification. Then, the studied scenario considers a transition from a PWRs plutonium mono-recycling fleet to a plutonium multi-recycling fleet. Vitrified waste container production is calculated as a function of different material reprocessing options. Simulations shows that up to 19% variation may be observed (in 2060) in canisters’ total number depending on the different assumptions. Impact of vitrification parameters such as the size of buffer before vitrification is also analysed and the importance of mixing material coming from MOX and MIX spent fuels with material from UOX spent fuels is clearly established

Synthesis of Nanocrystalline PuO₂ by Hydrothermal and Thermal Decomposition of Pu(IV) Oxalate: A Comparative Study

In recent years, the hydrothermal conversion of actinide (IV) oxalates into nanometric actinide dioxides (AnO2) has begun to be investigated as an alternative to the widely implemented thermal decomposition method. We present here a comparison between the hydrothermal and the conventional thermal decomposition of Pu(IV) oxalate in terms of particle size, morphology and residual carbon content. A parametric study was carried out in order to define the temperature and time applied in the hydrothermal conversion of tetravalent Pu-oxalate into PuO2 and to optimize the reaction conditions

FRENCH SCENARIOS TOWARD FAST PLUTONIUM MULTI-RECYCLING IN PWR

International audienceIn France, the COSI6 software can simulate prospective scenarios of nuclear energy evolution. Nuclear scenarios focused these last years on the development of SFR technology. However, SFR are more expensive to build than thermal reactors. In case SFR would not become economically competitive in the next decades, MOX spent fuels would pileup in the backend of the fuel cycle, unless alternative solutions of plutonium management in PWR were found. In this study, advanced EPR (European Pressurized water Reactor) fuel designs are applied to enable plutonium multi-recycling and stabilization of all spent fuel: CORAIL refers to fuel assemblies containing LEU and MOX rods, and MIX (also called MOXEUS) to assemblies where fuel rods are composed of plutonium mixed with enriched uranium. Scenarios results reveal that introducing MIX and CORAIL in EPR by the middle of the century can lead to a fast stabilization of spent fuel and plutonium inventories. With respect to open cycle, more minor actinides (MA) accumulate (about +70%), but the production of transuranic elements (Pu + MA) remains almost 3 times less. Furthermore, all high-level wastes are now packaged for long-term storage. Besides, spent fuels still contain significant quantities of fissile uranium. In MIX scenarios however, this uranium may be enriched and easily recycled into dedicated EPR for efficient natural uranium savings. In this case, the resource balance is significantly better than in open cycle (-30%). Multi-recycling in PWR appears therefore to be a viable temporary solution, allowing for spent fuels and wastes management until we expect the running out of natural uranium