A due diligence program has been performed to investigate the use of potassium hydroxide, in place of lithium hydroxide, as a pH modifier in the primary circuit of a pressurized water reactor. As part of this program, a series of stress corrosion cracking (SCC) initiation tests have been performed on sensitized 304 stainless steel in oxygenated primary coolant chemistry conditions, as may be present in occluded
locations such as canopy seals. The relative SCC initiation performance in standard LiOH primary water chemistry with high levels of dissolved oxygen has been compared with the molar equivalent in KOH chemistry. Testing was performed on cylindrical, actively loaded tensile specimens with in-situ DCPD monitoring to measure times to initiation. In the standard primary water conditions, but with high levels of dissolved oxygen (500 ppm), both tests progressed to initiation relatively quickly, with SCC initiation occurring in less than 100 hours. The times to initiation for sensitized 304 stainless steel in this environment were similar for the lithium- and
potassium-based chemistries.