Radiation Buildup on Stainless Steel in a Boiling Water Reactor Environment

Cobalt-60 contained in reactor water primarily causes contamination of boiling water reactor (BWR) out-of-core components. To elucidate the contamination mechanism, the deposition of radionuclides on stainless steels has been evaluated in actual reactor water at a commercially operating BWR. No significant difference was observed between Types 304 and 316L stainless steel. The deposition rate of ⁶⁰Co was mainly controlled by the growth of oxide films formed on steel. The deposition kinetics of anion ⁵¹Cr was very different from that of cations ⁶⁰Co and ⁵⁸Co. An Arrhenius temperature dependence was established for the deposition rate of Co between 130 and 240°C.