Irradiation assisted stress corrosion cracking (IASCC) is a phenomenon caused by neutron irradiation of austenitic stainless steels (SSs). The crack growth rates (CGRs) of IASCC for boiling water reactor (BWR) components are needed for assessments to ensure component integrity. In this study, the effects of K / size of specimen (where K is the stress intensity factor) on the CGR of irradiated austenitic SSs under hydrogen water chemistry (HWC) conditions of BWRs were discussed. First, CGRs calculated by
the Hashimoto-Koshiishi model, which is a crack growth model of SCC, were compared with the experimental CGRs. Second, the cause of the discrepancy between the calculated and experimental CGRs was discussed from the viewpoint of the effects of K / size of specimen. Detailed analysis of the experimental conditions of the data showed that the possible influencing factors for the discrepancy were
not only the K-validity, but also dissolved hydrogen concentration. If dissolved hydrogen concentration was higher than 70 ppb, a remarkable increase of CGRs from their calculated prediction was found for the K region where the K-validity criterion was not satisfied. Experimental CGRs with relatively high dissolved hydrogen concentration could be reproduced by adjusting the strain distribution ahead of the
crack tip in the model calculation.