Effects of Gamma-Ray Irradiation and Sodium Sulfate on the IGSCC Susceptibility of Sensitized Type 304 Stainless Steel in High-Temperature Water

The effects of gamma-ray irradiation and sodium sulfate as an aqueous impurity on the intergranular stress corrosion cracking (IGSCC) susceptibility of sensitized type 304 (UNS S30400) stainless steel (SS) were studied through slow strain rate tests (SSRT) and corrosion potential measurements in high-temperature water that simulated the BWR normal water chemistry (NWC) and hydrogen water chemistry (HWC) conditions. The SSRT results demonstrated that IGSCC was accelerated by gamma-ray irradiation under the NWC condition, while it was suppressed under the HWC condition. These different effects are attributable to the radiation-induced corrosion potential shifts in the opposite directions depending on the water chemistry condition. When the sodium sulfate was injected up to 0.32 µS/cm of conductivity, IGSCC was observed even under the HWC condition, but it was suppressed by gamma-ray irradiation.