Development of probabilistic fracture mechanics analysis codes for reactor pressure vessels and piping considering welding residual stress

Onizawa, Kunio ; Nishikawa, Hiroyuki; Ito, Hiroto

Probabilistic fracture mechanics (PFM) analysis codes for reactor pressure vessel (RPV) and piping, called as PASCAL series are being developed at JAEA, For an RPV, PASCAL2 code has been developed which can evaluate the conditional probabilities of crack initiation and fracture under transient conditions such as pressurized thermal shock. Recent improvements on the PASCAL2 are related to weld overlay cladding. It is shown that the welding residual stress by cladding affects the fracture probability of RPV to some extent. For piping, considering stress corrosion cracking, PASCAL-SP has been developed. The PASCAL-SP evaluates the probabilities of piping failures such as leakage and break of safety-related piping according to Japanese regulation and rules. Residual stress distribution was determined by parametric FEM analyses after verifying with welding experiments. Effects of welding residual stress distribution as well as inspection accuracy have been studied.