Effects of transient type and flaw density on through-wall cracking frequency of reactor pressure vessel under pressurized thermal shock events

Masaki, Koichi*; Osakabe, Kazuya*; Katsuyama, Jinya  ; Katsumata, Genshichiro; Onizawa, Kunio 

To assure the structural integrity of a reactor pressure vessel (RPV) is one of the most critical issues to maintain the safe long-term operation of a nuclear power plant. In Japan, the assessment methods for RPV integrity using deterministic fracture mechanics are provided in Japan Electric Association Code (JEAC). Meanwhile, a regulation on the fracture toughness requirements against PTS events based on a probabilistic fracture mechanics (PFM) analysis has been established in the U.S. In this paper, in order to apply probabilistic approach to domestic regulation, sensitivity analyses for flaw density or transient by reference to the data in the U.S. were performed using a PFM analysis code PASCAL3. We evaluated the effect of the flaw density or transient on through-wall cracking frequency (TWCF) and showed the specific example as a practical use of PFM.