Correlation between grain boundary strength determined by impact test of miniature specimen and stress corrosion cracking resistance of irradiated austenitic steels used for the internals of WWER-type and PWR-type nuclear reactors

•The method for estimation of grain boundaries strength of irradiated austenitic steels has been proposed that allows to perform the express-evaluation of SCC resistance.•Austenitic chromium-nickel 321, 316 and 304 stainless steels irradiated up to 125 dpa in different neutron energy spectra have been investigated by impact bending tests of miniature specimens and scanning electron microscopy.•The influence of the damage dose and neutron energy spectrum on the GBs strength is primarily due to an increase in helium concentration.•The strong correlation between the SCC resistance of austenitic chromium-nickel steels in the primary water environment and the GB strength has been shown. Austenitic chromium-nickel 321, 316 and 304 stainless steels used for internals of PWR (pressurized water reactor) and WWER (water-water energetic reactor) reactors were irradiated to 4–125 dpa in different neutron energy spectra and investigated by impact bending tests of miniature specimens. Relying on these tests, the effects of neutron dose and neutron energy spectrum on the intergranular fracture energy determining grain boundary strength have been analyzed. Two neutron spectra were considered. One spectrum is typical of the core of light water moderated reactors PWR and WWER, another spectrum is typical of the core of fast neutron reactors (FR). A correlation between resistance to stress corrosion cracking (SCC) and grain boundary strength in irradiated chromium-nickel 321, 316 and 304 stainless steels has been found.