Performance verification of Passive Accident Mitigation Scheme (PAMS) under feedwater line break (FLB) accident

Shi et al. (2015) analyzed the PAMS operation characteristics under Station Blackout (SBO) accident using RELAP5. In order to assess the ability of PAMS, more analyses should be carried out. This paper takes the Westinghouse-designed Advanced Passive PWR (AP1000) as research object and proposes the simulation performance verification of PAMS under FLB accident with the help of RELAP5. Moreover, the comparative analysis is also conducted between PAMS and traditional secondary circuit PRHRS with different design capacities under FLB accident. Results show that: during the whole accident process, the key parameters' performances of primary system could meet acceptance criteria requirements, which proves PAMS can cope with FLB accident; moreover, since only the PAMS train connected to intact circuit can operate to mitigate FLB accident, the analysis results prove that PAMS design satisfies single failure criterion; the primary system cooling process with PAMS operation is quite close to primary system cooling process with 4% of Full Power (FP) design capacity PRHRS operation, and both of them can remove core residual heat significantly under FLB accident.