Benchmark Analysis on the Failure Probability Assessment of Piping With Stress Corrosion Cracks

This paper describes the benchmark analysis of two probabilistic fracture mechanics (PFM) codes developed for structural reliability evaluation of primary loop recirculation system (PLR) piping of a boiling water reactor (BWR) in which the stress corrosion cracking (SCC) has been observed frequently in recent years. The two codes PASCAL-SP and PEPPER-M used for benchmark analysis have been independently developed by Japan Atomic Energy Agency (JAEA) and TEPCO systems Corporation (TEPSYS), respectively. After the validity of the procedure of analysis in these codes was conformed, the reliability assessment of PLR piping containing cracks due to stress corrosion cracking (SCC) was carried out according to some regulatory requirements and the rules on fitness-for-service in Japan. The analytical results from both codes were well in agreement. Through comparison of the results, influences of some items and input parameters on failure probabilities were identified.