Benchmark analysis and numerical investigation on probabilistic fracture mechanics analysis codes for NPPs piping

In this paper, a benchmark analysis was conducted using two probabilistic fracture mechanics analysis codes for aged piping in nuclear power plants, in order to confirm their reliability and applicability. These analysis codes have been improved or developed in Japan for the structural integrity evaluation and risk assessment considering the age related degradation mechanisms. In the benchmark analysis, the primary loop recirculation system piping in the boiling water reactor was selected as the typical piping system and stress corrosion cracking and fatigue were taken into account as the typical aging mechanisms. Moreover, a criterion was proposed for judging whether the differences between analysis results from the two codes are acceptable. This criterion is useful for general benchmark analysis of probabilistic fracture mechanics analysis codes. Based on the benchmark analysis results and numerical investigation, it was concluded that the analysis results of these two codes agree very well.

► We developed PFM analysis codes for integrity evaluation and risk assessment.
► We conducted benchmark analysis on different PFM analysis codes.
► A criterion was proposed to verify the results from different PFM analysis codes.
► Typical piping system in BWR plant was selected as the analysis object.
► SCC and fatigue were considered as the typical aging mechanisms.