An FE-MCS based modeling method for event sequence development for the multi-module probabilistic risk assessment

Abstract

The Multi-Unit Probabilistic Risk Assessment (MUPRA) has been a research hotspot since the Fukushima Daichi accident in 2011. Among the technical elements, event sequence modeling is the most challenging one in MUPRA implementation. During the PRA development for a 600 MW HTR-PM nuclear power plant (HTR-PM600) which consist of 6 reactor modules, we find that the complexity of the obtained event sequence model increases rapidly and massively with the number of reactors, therefore it is quite difficult to guarantee the modeling correctness. To address this issue, in this paper, we propose a multi-module event sequence modeling method based on Minimal Cut Sets at the level of Functional Event (FE-MCS). The proposed method is illustrated with two cases in this paper, namely, Loss of Coolant Accident caused by the Isolatable Large breach in primary pressure boundary (LLOCA-I) and Loss of vital Direct Current bus (LSDC).