DOSE DEPENDENCE OF RADIATION HARDENING OF AUSTENITIC STEELS IN BOR-60 AT PWR-RELEVANT TEMPERATURES

摘要

Radiation hardening is of concern for light-water-reactor core internals since it reduces tensile ductility while increasing yield strength. The increase in strength may contribute to irradiation assisted stress corrosion cracking susceptibility. Most studies report that the radiation hardening at 275 "C of austenitic stainless steels saturates at around 5-10 dpa. In the current research, microstructural evolution of austenitic stainless steels irradiated to 5 and 10 dpa at 325 "C in BOR-60 was studied using transmission electron microscopy. Combined with previously reported data from 25 dpa specimens, a dose dependence of the irradiation-induced defect structure is obtained for austenitic stainless alloys at PWR-relevant temperature. Additionally, dislocation loop sizes and densities are correlated with yield strength changes as measured in slow strain rate tests.