The concept of Molten Salt Fast Reactor (MSFR): Molten Salt Reactor with a Fast Neutron Spectrum
Presentation of the MSFR concept
The CNRS has been involved in molten salt reactors since 1997. Starting from the Molten Salt Breeder Reactor project of Oak-Ridge, an innovative concept called Molten Salt Fast Reactor or MSFR has been proposed, resulting from extensive parametric studies in which various core arrangements, reprocessing performances and salt compositions were investigated to adapt the reactor in the framework of the deployment of a thorium based reactor fleet on a worldwide scale (see next paragraph below). The primary feature of the MSFR concept is the removal of the graphite moderator from the core (graphite-free core), resulting in a breeder reactor with a fast neutron spectrum and operated in the Thorium fuel cycle. This "reference MSFR" (large power reactor operated in the Th fuel cycle) has been recognized as a long term alternative to solid fuelled fast neutron systems with unique potential (negative safety coefficients, smaller fissile inventory, easy in-service inspection, simplified fuel cycle…) and has thus been selected for further studies by the Generation IV International Forum in 2008.
In the MSFR, the liquid fuel processing is part of the reactor where a small side stream of the molten salt is processed for fission product removal and then returned to the reactor. This is fundamentally different from a solid fuel reactor where separate facilities produce the solid fuel and process the Spent Nuclear Fuel. Because of this design characteristic, the MSFR can thus operate with widely varying fuel composition. Thanks to this fuel composition flexibility, the MSFR concept may use as initial fissile load, 233U or enriched (between 5% and 30%) uranium or also the transuranic elements currently produced by PWRs in the world.
A safety analysis methodology for such a liquid circulating fuel reactor has been developed in collaboration with IRSN, Framatome and Politecnico di Torino in the frame of the SAMOFAR (Safety Assessment of the Molten Salt Fast Reactor) European project of the H2020 program.
New studies are being conducted in the MSFR team on other kinds of MSFR, such as a Small Modular Reactor (SMR) of reduced power and operated in the U/Pu or Th/233U fuel cycles.
For more details, please consult the bibliography page of the MSFR.