Fundamental safety strategy against severe accidents on prototype sodium-cooled fast reactor

ナトリウム冷却高速原型炉のシビアアクシデントに対する基本的な安全戦略

小野田 雄一 ; 栗坂 健一 ; 堺 公明

Onoda, Yuichi; Kurisaka, Kenichi; Sakai, Takaaki

The accident categories of severe accidents (SAs) for prototype Sodium-cooled Fast Reactor (SFR) which need proper measures were investigated through the internal event PRA and event tree analysis for the external event and six accident categories, ULOF, UTOP, ULOHS, LORL, PLOHS and SBO, were identified. Fundamental safety strategy against these accidents is studied and clearly stated considering the characteristics and existing accident measures of prototype SFR, and concrete measures based on this safety strategy are investigated and organized. The sufficiency of these SA measures is confirmed by comparing the evaluated Core Damage Frequency (CDF) and Containment failure frequency (CFF) to the target value, 110 and 110 per plant operating year, respectively, which were selected based on the IAEA's safety target. However, the target value of CDF and CFF should be satisfied considering all the SAs caused by both internal and external events. External event PRA for prototype SFR is now under evaluation and we set out to satisfy the target value of CDF and CFF considering both internal and external events.