A preliminary hybrid model of irradiation-assisted stress corrosion cracking of 300 series stainless steels in PWR primary environments

The hybrid model of PWR primary water stress corrosion cracking (PWSCC) in unirradiated Ni alloys presented at the 2009 Environmental Degradation meeting has been extended to irradiated stainless steels in PWR primary environments in a pilot effort reported here. The preliminary IASCC model is an empirical/theoretical hybrid strain rate model that combines submodels developed by various investigators. The major differences from the PWSCC model include using the Rice-Drugan-Sham (RDS) theoretical expression for strain rate near a growing crack in elastic-perfectly plastic materials and including an empirical dose function. The RDS strain rate expression is appropriate for highly-irradiated materials that show little or no strain hardening. The dose function incorporates many investigators' observations that irradiation has little effect on SCC below some low dose, then an increasing effect as dose increases until there is no further effect above a high-dose saturation level.