Application of Preoxidation Treatment to Suppress ⁶⁰Co Deposition on Stainless Steel Surfaces of Boiling Water Reactor Primary Cooling Systems

⁶⁰Co accumulation on boiling water reactor (BWR) primary cooling pipings. To demonstrate the treatment effect, test specimens, which had been exposed to simulated BWR water in an autoclave (temperature, 286 °C; pH, 7; oxygen concentration, 200 ppb) for up to 200 h, were installed in the Hatch-2 inplant loop and their ⁶⁰Co deposition amounts were compared with those of as-received specimens. Preoxidation treatment for 200 h resulted in deposits of about one-fourth those of as-received specimens. It was estimated that the maximum amount of ⁶⁰Co deposited on primary piping during the entire plant operation life (30 yr) would be reduced to about one-half of that without preoxidation treatment if the ⁶⁰Co concentration in the reactor water was constant.