Development of probabilistic evaluation models of fracture toughness K and K for Japanese RPV steels

Katsuyama, Jinya  ; Katsumata, Genshichiro; Onizawa, Kunio ; Osakabe, Kazuya*; Yoshimoto, Kentaro*

Probabilistic fracture mechanics (PFM) analysis code PASCAL3 has been developed to apply the PFM analysis to the structural integrity assessment of domestic RPVs. In this paper, probabilistic evaluation models of fracture toughness KIc and KIa which have the largest scatter among the associated factors based on the database of Japanese RPV steels are presented. We developed probabilistic evaluation models for KIc and KIa based on the Weibull and lognormal distributions, respectively. The models are compared with the existing lower bound of fracture toughness in the Japanese code and probabilistic model in USA. As the results, the models established in present work satisfy lower bounds of fracture toughness in the Japanese code. The comparison in the models between present work and US showed significant differences that may have an influence on fracture probability of RPV.