France-Japan collaboration on the SFR severe accident studies; Outcomes and future work program

ナトリウム冷却高速炉のシビアアクシデント研究に関する日仏協力成果と計画

久保 重信 ; Payot, F.*; 山野 秀将   ; Bertrand, F.*; Bachrata, A.*; Saas, L.*; Journeau, C.*; Gosse, S.*; Quaini, A.*; 柴田 明裕*; 飯塚 透*; Czarny, O.*

Kubo, Shigenobu; Payot, F.*; Yamano, Hidemasa; Bertrand, F.*; Bachrata, A.*; Saas, L.*; Journeau, C.*; Gosse, S.*; Quaini, A.*; Shibata, Akihiro*; Iitsuka, Toru*; Czarny, O.*

The paper presents major outcomes of the France-Japan ASTRID collaboration and the work program from 2020 to 2024 in the field of severe accident study. In the ASTRID collaboration, severe accident sequences were summarized based on the various safety analyses for the important accident phases, which contributed to strengthen the confidence in the ASTRID severe accident progression for a robust safety demonstration and identification of R and D programs of common interest. Collaborative analysis has been conducted to evaluate ASTRID mitigation device efficiency for mitigation of power excursions, material relocation, debris bed and molten pool behavior on the core catcher. The methodology for mechanical consequence assessment was also developed. In order to support the reactor studies, experimental studies have been planned and conducted regarding the reaction of core material mixtures, in-pile experiments for the fuel pin failure and material relocation through a steel duct structure, and out-of-pile experiments for the fuel coolant interaction (FCI) in the sodium pool. Severe accident analysis tool SIMMER-V with new simulation capabilities and SEASON platform have also been developed. Based on these successful achievements, several tasks to study the large fields of the severe accident domain, which include development of severe accident analysis methodologies and synthesis of SA sequences and consequences, thermodynamics, kinetic and thermo-physical studies of core material mixture, development and validation of SIMMER-V, experimental programs on the molten core material relocation and FCI. After defining the technical contents and implementation plans, the five years study programs have been started.