Optimizing the burning efficiency and the deployment capacities of the molten salt fast reactor

paper 9149; International audience; Molten salt reactors in the present configuration, called Molten Salt Fast Reactors (MSFR), have been selected for further studies by the Generation IV International Forum. These reactors, characterized by a fast neutron spectrum, may be operated in simplified and safe conditions in the Th/233U fuel cycle with fluoride salts. Since 233U does not exist on earth and is not being directly produced today, we investigated the possibility of using, in this MSFR concept, the transuranic elements (TRU) currently produced in the world as an initial fissile load. We present here the concept, before focusing on a possible optimization in terms of minimization of the initial fissile inventory and improvement of the burning efficiency. Our studies demonstrate that an initial fissile inventory around 4 to 5 metric tons per GWe may be easily reached with a burning rate after 50 years of operation ranging from 87% to 93%. These studies also bring to light the limitations of the concept due to the irradiation damages to the structural materials. We conclude that this issue will have to be studied in depth to allow a realistic evaluation of the global possibilities of such a reactor.