Effects of crack existing distribution and transient loads on fracture probability of reactor pressure vessel

Onizawa, Kunio ; Matsuzawa, Hiroshi*

Concerning the probabilistic structural integrity analysis method, the effects of crack existing probability and transients on the fracture probability of reactor pressure vessel (RPV) have been investigated based on the pilot plant analyses performed at the U.S.NRC. In addition to the comparisons of stress intensity factor and temperature during typical PTS events, we studied the correlation between analysis results by deterministic and probabilistic methods using probabilistic fracture mechanics (PFM) analysis code PASCAL2. From the PFM analyses by PASCAL2, the effects of crack existing probability and transient loadings on the fracture probabilities of a typical RPV were investigated. It was concluded that the crack existing probability had much influence on the fracture probabilities. The model on the crack existing probability for a PWR plant in USA resulted in less fracture probability than the current PASCAL2 model developed at PNNL previously. It was also shown that the transient loading had little effect on the correlation between deterministic safety margin and corresponding probabilistic analysis result, i.e. fracture probability.