Development of probabilistic fracture mechanics analysis code for aged piping under stress corrosion cracking

Onizawa, Kunio ; Ito, Hiroto

Since probabilistic fracture mechanics (PFM) analysis method treats the scatter and uncertainties of data related to aging degradation, it is, therefore, useful to apply the PFM analysis to the piping reliability evaluation. Stress corrosion cracking (SCC) has been observed at some piping joints made by Austenitic stainless steel in BWR plants. In JAEA, we have been developing PFM analysis code, PASCAL-SP, for aged piping based on the latest knowledge on SCC. The PASCAL-SP evaluates the failure probability of piping at aged welded joints under SCC by a Monte Carlo method. Although many factors have some influence on failure probabilities in the PFM analysis, we are mainly focusing on the effects of in-service inspection and welding residual stress distribution. Through parametric PFM analyses by the PASCAL-SP, the effects of in-service inspection and the uncertainties of residual stress distribution on the failure probability are studied.