TARGET ACCURACY REQUIREMENTS AND AN EVIDENCE-BASED BACKGROUND FOR MSFR SAFETY ASSESSMENT

The paper presented on International Conference on Fast Reactors and Related Fuel Cycles (FR22), Viena, Austria, 22 April 2022

From the very beginning of nuclear era the mission of fast neutron reactors has been conceived in a double functionality as a source of energy and, at the same time, of artificial fissile materials that would allow making nuclear power resources practically inexhaustible. Since then we continue considering any fast neutron reactor to be an element of the global fuel cycle, adding one more function like to transmute or incinerate multi-recycled plutonium and minor actinides. The molten salt systems we are discussing the article might combine, in opposite to traditional solid fuel ones, a source of power and a large part of the external nuclear fuel cycle at the same site in the same unit. Such concepts need to be controllable needs to be supported by complex simulations with an enhanced predictive capability maturity. The last one should be proved in a comprehensive validation process somehow involving a significant number of representative experimental data. Since no one available experiment might be accepted as a fully representative one these validation process should rely, mainly, one several non-exact cases. Among them, we are prioritizing the following aspects: 1) how far the data useful in terms of  reactor control in normal and accidental states, 2) optimized proportion between nuclear-driven and non-nuclear cases involved in the validation turnover, and 3) how realistic would be identified target accuracy requirements for the best-estimate and penalized modeling. The paper briefly discusses some ideas on an establishment of problem-oriented evidence-based background for the innovative molten salt fast neutron nuclear systems.