Abstract
The P-PIE (Probabilistic Piping Integrity Evaluation Program) code to evaluate the pipe failure probability was developed in this study under stress corrosion cracking (SCC) and fatigue condition. The validation of the P-PIE code was performed by comparison with other codes. By using P-PIE program, the pipe failure probabilities of the reactor coolant system in Korean PWR (Pressurized Water Reactor) plants were evaluated. 3 reactor types including Westinghouse 2-loop plants (WH-2), Westinghouse 3-loop plants (WH-3), and Framatome 3-loop plants (FR-3 which are operating in Korea, were considered in the evaluation. The effect of SCC-related variables such as oxygen concentration during start up and steady state operation, and operating temperature on the piping failure probabilities was investigated. The effects piping loops and reactor types on the piping failure probability were also investigated. The results show that (1) LOCA (loss of coolant accident) probability of Korean PWR plants is extremely low, (2) leak probability is sensitive to pipe thickness, operating temperature and oxygen concentration during steady state operation under SCC, (3) net section stress criterion gives more conservative results than tearing modulus criterion under fatigue, and (4) PSI and ISI can reduce pipe failure probability.
