Reliability of passive residual heat removal system based on PSA

Currently the equipment reliability has been studied when the probabilistic safety assessment (PSA) of advanced nuclear reactor is used to analyze the reliability of the passive system. However, the physical reliability has not yet been considered in PSA. On the other hand, the study of equipment reliability has been focused on all the start-up equipment rather than on the equipment in operation when the equipment reliability and physical reliability are discussed in a holistic fashion. In view of the aforementioned issues, this paper analyzed the equipment reliability sensitivity of the system based on the AP1000 passive residual heat removal system (PRHRS) subjected to the loss of normal feedwater supply. The system reliability is integrated into PSA model by self-developed synthesis method, which takes into account the demand failure of active equipment and the operation failure of passive equipment, and analyzes the sensitivity of system equipment reliability. The results show that the spectrum of the accident sequence obtained by the comprehensive method is more real and comprehensive when it is used to analyze the reliability of PRHRS, which is superior to the traditional method. (authors)