In-vessel retention of unprotected accident in a fast reactor; Assessment of material-relocation and heat-removal behavior in ULOF

高速炉の炉停止失敗事象における炉容器内終息(IVR)に関する検討; ULOF再配置/冷却過程における評価

曽我部 丞司 ; 鈴木 徹; 和田 雄作; 飛田 吉春

Sogabe, Joji; Suzuki, Toru; Wada, Yusaku; Tobita, Yoshiharu

The achievement of in-vessel retention (IVR) of accident consequences in an unprotected loss of flow (ULOF), which is one of the technically inconceivable events postulated beyond design basis, is an effective and rational approach to enhancing the safety characteristics of the sodium-cooled fast reactor. The objective of the present study is to show that the decay heat generated from the relocated fuels would be stably removed in post-accident-material-relocation/post-accident-heat-removal (PAMR/PAHR) phase, where the relocated fuels mean fuel discharged from the core into low-pressure plenum through control-rod guide tubes, and fuel remnant in the disrupted core region (non-discharged fuel). As a result of the assessment, it can be concluded that the stable cooling of the relocated fuels was confirmed and the prospect of IVR was obtained.