Development of the accident management measures in the prototype sodium-cooled fast reactor in Japan

日本のナトリウム冷却高速原型炉におけるアクシデントマネジメント策の整備

栗坂 健一 

Kurisaka, Kenichi

The purpose of this presentation is to provide practical examples in the development of accident management programmes for advanced reactors. As part of development of sodium-cooled fast reactor (SFR) in Japan, JAEA developed the prototype SFR. To enhance the provisions in defense-in-depth (DiD) level 4, accident management (AM) measures of the prototype SFR in Japan were studied and developed. The scope of topics is focused on AM measures for prevention of core damage. Fundamental safety functions of the prototype SFR are (1) reactor shutdown, (2) maintaining reactor coolant level, and (3) decay heat removal. For each safety function, challenge mechanisms, plant vulnerabilities, and plant capabilities were considered in the AM development process. Representative AM measures for the safety functions are (1) de-energizing the control rod holding electromagnet, (2) siphon-break of the leak path against second leak in the primary heat transport system, and (3) switching to natural circulation cooling.