照射ステンレス鋼の材料特性に基づくBWR炉内構造物の破壊評価に関する検討

抄録

The methods and criteria of structural integrity evaluation for Irradiation Assisted Stress Corrosion Cracking (IASCC) of Boiling Water Reactor (BWR) internal components are provided in the JSME fitness-for service code. The fracture evaluation methodology, however, was developed based on linear-elastic fracture mechanics, considering the decrease in ductility due to neutron irradiation with limited materials testing data and knowledge available at that time. In this study, applicability of fracture evaluation methodology based on the elastic-plastic fracture mechanics was investigated for a core shroud with a crack due to IASCC. The fracture mode evaluations with failure assessment diagram (FAD) were performed by using the material properties of irradiated austenitic stainless steels, which vary with increasing neutron fluence.