Laboratory studies on hydrogen water chemistry

Intergranular stress corrosion cracking (IGSCC) in the weld heat-affected zones of austenitic stainless steel piping has adversely affected the availability of boiling water reactors (BWRs). A promising method of mitigating IGSCC susceptibility of pipe welds involves suppression of coolant oxygen by addition of hydrogen gas to the plant's feedwater. The hydrogen recombines with the radiolytically produced oxygen and reduces the chemical driving force for IGSCC below the threshold value. A series of studies was performed in the laboratory to demonstrate that this modified environment not only inhibits IGSCC of sensitized stainless steel, but also provides additional margin against environmental cracking for other BWR materials. The results of these studies demonstrate that this technique has a high probability of success