Communication Dans Un Congrès Année : 2022

Stakes and scientific challenges for a sustainable use of Uranium and Plutonium in the French nuclear fuel cycle

Résumé

The current French recycling strategy takes advantage of the 10 MT of plutonium produced annually by the irradiation of the UOX fuel in the French LWR fleet. This recycling strategy aims at saving natural uranium resources as well as decreasing the net production of plutonium, safely recovered and recycled in the MOX fuels. It also limits the necessary interim storage and future final disposal capacities and prevents any residual plutonium content in the high-level nuclear glass waste. Although the feasibility of MOX reprocessing is already considered proven at an industrial scale, the used MOX fuel (100-120 t/y), which still contains a fraction of potentially reusable plutonium, is currently untreated and stored. The French Energy Transition Act and the Multi-annual Energy Program (2019-2028) make several commitments and notably: I. net zero CO2 emissions by 2050, II. Decreasing the share of nuclear energy in the electric mix down to 50% by 2035, and shutting down 14 LWRs by 2035 consequently; recent presidential announcements are however in favor of extending the lifetime of existing reactors and building soon new EPRs (6 initially with a study of 8 more). III. Increasing the amount of renewable energies in the mix consequently. IV. Maintaining the recycling strategy at least until the years 2040. The MOX fuel is currently used in the 900 MWe LWRs, which will be shut down first; partially “MOXing” the 1300 MWe LWRs will compensate this. In the long run (on the horizon of the end of the 21st century), the nuclear industry has to be prepared for a potential forthcoming lack of natural uranium available at an economically viable cost. Therefore, a sustainable closed fuel cycle strategy makes it necessary to introduce the 4th Generation fast neutron reactors into the fleet, which are able to take the best benefit of every actinide isotopes through a better neutron fission/absorption ratio. The option of using molten salt reactors to carry out the transmutation of actinides is also under study, with specific scientific challenges at stake. Meanwhile, French industry should pave the way for multi-recycling Pu and U in the current LWRs. The option of multi-recycling plutonium in LWRs implies an increase in the plutonium flux and a degradationof the plutonium isotopic composition, which induces several hurdles concerning the safety, radiation protection and operating conditions of the reactors and the fuel cycle (reprocessing and fabrication). In particular, concerning the fuel cycle, a dedicated R&D program addresses innovative options for reprocessing (dissolution of more refractory oxide pellets, simplified separation process). In this talk, we address the main scientific challenges associated with this step-by-step strategy towards a sustainable Pu « full recycling » and highlight the need for improvements and simplifications in the MOX fuel reprocessing and manufacturing operations required by the notably increasing quantity of degraded plutonium in the fuel cycle.
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Dates et versions

cea-04818149 , version 1 (04-12-2024)

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  • HAL Id : cea-04818149 , version 1

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Gilles Bordier. Stakes and scientific challenges for a sustainable use of Uranium and Plutonium in the French nuclear fuel cycle. Plutonium Futures - The Science 2022, French Alternative Energies and Atomic Energy Commission (CEA), Sep 2022, Avignon, France. ⟨cea-04818149⟩

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