To assess the structural integrity of a reactor pressure vessel (RPV) during pressurized thermal shock (PTS) events quantitatively, several probabilistic fracture mechanics (PFM) codes have been developed. In PTS reevaluation project in the United States, PFM analysis using FAVOR has been conducted to obtain screening criteria for PTS. To consider the future application of the probabilistic method to the code in Japan, authors have conducted deterministic and probabilistic analyses using PASCAL3 and evaluated the effects of transient loads on brittle crack initiation and fracture. The results showed that the structural integrity of a RPV could be assessed quantitatively through the evaluation of fracture probabilities.
