An Alkaline Prefilming Process for the Primary Piping in a New Japanese Boiling Water Reactor

A prefilming method called the alkaline process was successfully applied to a new Japanese boiling water reactor plant during the nuclear heatup phase during the plant preoperation phase. This method was developed to suppress deposition of radioactive corrosion products such as ⁶⁰Co on ex-core components, which are primarily made of stainless steel. When stainless steel is exposed to actual reactor water that contains oxygen at pH of 8.0 to 8.5, at 288°C, for 410 h, corrosion-resistant oxide films can be formed. The results of the exposure tests indicate that an ∼30% reduction in the deposition of ⁶⁰Co and ⁵⁸Co was obtained by this process compared to ordinary operation procedures.