Abstract
Plant life management is one of the most important issues to improve safety of LWR in Japan. It is known that austenitic stainless steels, which are the construction materials of reactor internals, has susceptibility to irradiation assisted stress corrosion cracking (IASCC) due to high neutron irradiation, and some incidents of IASCC in core shroud of Japanese BWR plants have been reported. Recently, structural integrity assessment method for IASCC has been prepared as "IASCC evaluation guide for BWR core internals". However, since the results of structural integrity assessment would be so conservative relative to the actual experiences of IASCC in BWR plants, the rationalization of structural integrity assessment method is desirable. In this study, IASCC crack growth analysis considering distribution of neutron flux in core shroud was investigated. It was found that crack growth period evaluated by this method was longer than that evaluated by existing method in which neutron flux on the inner surface of core shroud was applied to whole of thickness, at the maximum. It is considered that IASCC crack growth analysis investigated in this study is effective to the rationalization of structural integrity assessment method for IASCC.
