Developments of probabilistic fracture mechanics analysis codes for reactor pressure vessel and piping

Onizawa, Kunio ; Shibata, Katsuyuki; Suzuki, Masahide

The probabilistic fracture mechanics (PFM) method has been recently highlighted to rationally incorporate the uncertainties arising from the material properties, defect distribution, inspection quality and so on, unlike the conventional deterministic method. We are developing analytical codes for PFM analysis of RPV and piping under design base loading conditions such as transient loading and seismic loading. In JAEA, the PFM codes called as PASCAL (PFM Analysis of Structural Components in Aging LWRs) series have been developed. For reactor pressure vessel (RPV), PASCAL code has been developed which can evaluate the conditional probabilities of crack initiation and fracture under transient conditions such as pressurized thermal shock (PTS) considering neutron irradiation embrittlement of the material in the beltline region. For piping, considering aging degradation and seismic stress calculated with seismic hazard, piping reliability analysis codes have been developed. PASCAL-SC and PASCAL-EC analyze failure probability of piping under operational and seismic stresses considering stress corrosion cracking and flow accelerated corrosion, respectively. The outlines and some results of these computer codes are described.