MultI-recycling strategies of LWR SNF focusing on MOlten SAlt technology

Multi-recycling in LWRs is a tangible solution enhancing further the circular economy and moving towards the closure of the fuel cycle. However, this option presents some limitations related to the degradation of the Pu isotopic composition and the generation of minor actinides (MA), leading to an increase of vitrified high-level waste when compared to multi-recycling with FRs, thus limiting its benefits from a repository footprint perspective.

Significant improvement in converting all the Pu isotopes and MA into fission products with shorter half-lives can be achieved with the introduction of advanced reactor systems, among which the molten salt reactor (MSR) using Chloride salt is particularly promising. In this reactor, the fuel is a fluid, eliminating the major technological bottlenecks of refabrication of solid fuels with high transuranic content.

There is no experience of Chloride MSRs (Cl MSR) in operation, but it was studied and tested on experimental set-ups, showing a great improvement in the conversion rate of actinides.

For these reasons, MIMOSA aims to develop an accessible, cost/risk optimised multi-recycling strategy of LWR spent fuels, based primarily on multi-recycling of Pu (and REPU) in LWRs combined with the Cl MSR, and using already available infrastructure in the EU such as the French reprocessing plant, not only for its existing LWR fuel treatment capabilities, but also for its Pu partitioning and waste conditioning capabilities, its compatibility with chloride salts, and in the future, for its potential additional capabilities in MA separation and salt management. This strategy will also be compared with other multi-recycling scenarios.

MIMOSA focus more specifically on the demonstration of several key aspects of technical feasibility and performance of Cl MSRs, that will contribute to accelerating the deployment of this advanced technology, on Pu and MA conversion respectively and on production of valuable isotopes for other applications