抄録
Regarding the long-term storage of spent Cs adsorption vessels containing zeolites in the Fukushima Daiichi nuclear power station, corrosion of the material of the spent Cs adsorption vessels is one of the important issues. We performed electrochemical tests of stainless steel (SUS316L) in the zeolites containing artificial seawater under gamma-ray irradiation. The spontaneous potential (ESP) and critical pitting potential (VC) of SUS316L were measured to understand the corrosion resistance of the stainless steel in this study. The rest potential of the stainless steel increased with time after gamma-ray irradiation. ESP, defined as the steady rest potential, increased with increasing dose rate; this increase in ESP was suppressed by the contact of SUS316L with the zeolites. The concentration of H2O2 in bulk water increased with increasing dose rate. This concentration increase was suppressed by the contact of SUS316L with the zeolites due to decomposition of H2O2. There was good relationship between ESP and the concentration of H2O2. The VC of SUS316L contacted with the zeolites decreased with increasing Cl－ ion concentration and is slightly smaller than the VC in bulk water. The contact of SUS316L with the zeolites suppressed the increase in ESP under irradiation. The contact with the zeolites can reduce the probability of the localized corrosion of SUS316L.
