Structural integrity evaluation of reactor pressure vessels during PTS events using deterministic and probabilistic fracture mechanics analysis

Osakabe, Kazuya*; Nishikawa, Hiroyuki*; Masaki, Koichi*; Katsuyama, Jinya  ; Onizawa, Kunio 

To assess the structural integrity of reactor pressure vessels (RPV) during pressurized thermal shock (PTS) events, a deterministic fracture mechanics approach has been widely used. According to Japan Electric Association Code (JEAC), the stress intensity factors (SIF) at the crack tip and the fracture toughness are calculated. The structural integrity is judged to be maintained unless the SIF during PTS events is less than fracture toughness. On the other hand, the application of a probabilistic fracture mechanics (PFM) analysis method has become attractive recently because uncertainties related to input parameters can be incorporated rationally. Probabilities of crack initiation and through-wall cracking can be obtained from PFM analyses. In this paper, in order to verify the applicability of a PFM method to JEAC, deterministic and probabilistic analyses have been performed and the effects of initial crack size on probability of crack initiation has been analyzed.