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Stress corrosion cracking (SCC) of type 304 (UNS S30400) stainless steel (SS) was studied using fracture mechanics-type standard compact tension (CT) specimens in simulated boiling-water reactor (BWR) environments at 288°C. Tests were performed under constant loading. Crack lengths and crack growth rates (CGR) were determined by the reverse direct current (DC) potential drop method. Fractography was used to determine the mode of cracking and to confirm validity of the potential drop method for crack length determination. Test environments were high-purity deionized water with < 10 ppb to 440 ppb dissolved oxygen (O2) 0 ppb to 570 ppb hydrogen peroxide (H2O2), and 14 ppb to 150 ppb dissolved hydrogen (H2). CGR were found to be 4.9 × 10−8 mm/s to 3.0 × 10−7 mm/s at an initial stress intensity (K) of 31 MPa√m (100 kgf/mm1.5) in simulated normal water chemistry (NWC). However, the CGR was < 1 × 10−9 mm/s in simulated hydrogen water chemistry (HWC). CGR decreased with decreasing corrosion potential (E...

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.