Design and Safety Studies of the Molten Salt Fast Reactor Concept in the Frame of the SAMOFAR H2020 Project

Since more than 15 years, the National Centre for Scientific Research (CNRS, France) has focused R&D efforts on the development of a new molten salt reactor concept called the Molten Salt Fast Reactor (MSFR) selected by the Generation-IV International Forum (GIF) due to its promising design and safety features. Studies are performed to ascertain whether MSFR systems can satisfy the goals of Generation-IV reactors. Molten salt reactors are liquid-fueled reactors, allowing a large flexibility in terms of operation (load following capabilities…) or design (core geometry, fuel composition, specific power level…) choices. They are characterized by features different in terms of design, operation and safety approach compared to solid-fueled reactors. In the frame of the European SAMOFAR (Safety Assessment of Molten Salt Fast Reactors) project of Horizon2020, dedicated studies are performed on these topics. An overview of these studies will be presented in this article. Firstly, an innovative design of the MSFR fuel circuit (defined as the circuit containing the fuel salt during power generation) and of the emergency draining system has been defined and is under optimization in terms of safety. Such reactors also call for the definition of dedicated operational procedures different from that of solid-fueled reactors, requiring the use of specific modelling tools (multiphysics and system codes). A system code is thus under completion and validation in the frame of SAMOFAR to define the start-up and load following procedures of the MSFR, including the evaluation of safety transients. Finally, a safety approach dedicated to liquid circulating fuel reactors has been developed on the basis of the ISAM methodology of the GIF taking into account other safety methodologies and guidelines. An application procedure and the required tools have been proposed. The approach is being applied to the MSFR, allowing a preliminary identification of initiating events, lines of defence and confinement barriers for the concept.