Fluence dependence of SANS and yield stress increase observed for low-Cu RPV steels

The investigation is focussed on three low-Cu RPV steels, JPB, JPC and JFL, irradiated at 255°C up to several levels of neutron fluence. The SANS data obtained will be discussed as a function of fluence and correlated with measured values of the yield stress increase. There is strong evidence for a late-blooming effect from both SANS and hardening. The results will be compared with those from similar investigations for RPV steels and model alloys irradiated at higher temperatures and higher flux.