PSA Analysis and Design Optimization for Reduction of Medium Safety Injection Pump Shut off Head of HPR1000

Through the probability safety analysis (PSA), it is found that in the design process of HPR1000, the reduction of the medium safety injection pump shut off head is beneficial to meet the steam generator tube rupture (SGTR) accident acceptance criteria, but it increases the core damage frequency (CDF) of loss of direct current accident. This paper puts forward the optimization scheme to add the rapid pressure relief valves for feed and bleed in the accident procedure. Applying this scheme to HPR1000, the PSA results show that the CDF of loss of direct current accident decreases from 2.4 × 10^-8 (reactor · year)^-1 to 2.2 × 10^-9 (reactor · year)^-1. So the optimization scheme proposed in this paper effectively reduces the risk of HPR1000. (authors)