Within the framework of the Generation IV Sodium-cooled Fast Reactor (SFR) R&D program of CEA (French Alternative Energies and Atomic Energy Commision), a methodology is proposed to enable the early consideration of safety in the undergoing design process. Before the use of mechanistic tools (CATHARE, SIMMER, APOLLO, etc.) that usually requires an advanced knowledge of the reactor design, this approach involves several physical tools dedicated to each physical phenomenon likely to govern the choice of design parameters. These tools are mostly based on simplified modelings (mostly 0D and 1D) and are carefully validated versus experimental results. They are gathered in a platform that covers all kind of accidental phenomenology, from the initiator (pump trip, reactivity insertion, local blockages, etc.) until the reach of a stable and coolable state after corium relocation. Thus, enabling a large number of simulations in a reasonable computational time, it makes possible the characterization of some major accident transient bifurcations (such as boiling onset, boiling stabilization, primary power excursion, molten fuel vaporization, corium axial relocation in transfer tubes, etc.), in terms of probability of occurrence and of consequences on the transient evolution. It also enables to identify the main physical parameters causing the bifurcations in order to allow a straight feedback on the core design and to give some orientation for future R&D studies. In this paper, a focus is firstly made on some scenario bifurcations to illustrate the platform abilities. The boiling onset and possible stabilization are studied. The possibility of power primary excursion depending on the core design is also addressed, and the fuel vaporization possibilities are finally assessed. Depending on these results, a global estimation of the core safety features is eventually provided for both prevention and mitigation features, at a quite early design stage. This allows a rapid comparison between core concepts or design options in order to facilitate the sketch of incoming safety-oriented SFRs.
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