Study on risk importance evaluation in dynamic PRA, 2; Survey on nuclear regulatory applications and trial calculation with dynamic level 2 PRA

Zheng, X. ; Tamaki, Hitoshi ; Maruyama, Yu ; Takada, Tsuyoshi  ; Narukawa, Takafumi*; Takata, Takashi*

The dynamic probabilistic risk assessment (dynamic PRA) methodology explicitly treats the dynamics of event progression, enabling risk assessment that does not require predefined scenarios or success criteria. Based on these characteristics, from the perspective of risk triplet, we investigated the concept and measures of risk importance in dynamic PRA. Furthermore, the importance measures were applied to a dynamic PRA to evaluate their effectiveness. In this presentation, the authors provide a review on the application status of traditional risk importance measures in nuclear regulatory activities, and by using quantities such as release amount (consequence) of time-dependent source term to the environment and associated containment failure frequency (CFF), they confirm the applicability of the proposed risk importance measure to dynamic Level 2 PRA.