実力基準保全による検査頻度の合理化（確率論的破壊力学による機器破損確率への影響評価）

Abstract

This study is aimed at applying the performance-based maintenance (PBM) concept to determine inspection schedule. Previously, the time-based maintenance concept has been applied to determine the inspection schedule for nuclear plant components. In the PBM concept, frequency of inspection is determined by operation time before the inspection. Duration before the next inspection is extended if the component indicates no cracking for a long time. In this study, the change in structural reliability due to applying the PBM concept was investigated by probabilistic fracture mechanics analyses. In order to calculate the probability of leakage or fracture (failure probability), growth of fatigue cracks initiated at the primary coolant pipe of pressurized water reactor nuclear power plants was simulated considering variations in yield and tensile strengths, fatigue crack growth rate, initial crack shape and so on. It was demonstrated that the failure probability was reduced by performing inspections according to the time-based maintenance concept. Frequency rather than detectability of inspection had a larger impact on reducing the failure probability. It was shown that, by applying the PBM concept, the number of inspections could be reduced significantly without increasing the failure probability. It was concluded that the PBM concept could optimize the inspection schedule.