Effect of bicarbonate ions on the cathodic reaction of copper electrodes in fresh groundwater environments

Miyoshi, Yuma*; Inoue, Hiroyuki*; Mitsui, Seiichiro  ; Dobashi, Ryuta*

In Japan, research and studies on direct disposal of spent fuel as an alternative disposal option are underway in order to secure a wide range of options. For direct disposal, a copper-carbon steel composite vessel covered with pure copper, which is expected to provide longer confinement, has been considered in consideration of the time required for sufficient attenuation of C-14, one of the dominant radionuclides in the safety assessment. In this study, the effect of HCO on the cathodic reaction of pure copper in a fresh groundwater environment with a low oxygen atmosphere was investigated. From the results of polarization measurements using pure copper as a test electrode, it was inferred that HCO promotes the cathodic reaction, which is a hydrogen evolution reaction using H as an oxidant, by buffering the pH change at the electrode interface in the relatively low current density range, which is assumed to be the cathodic current of corrosion. It is unlikely that HCO acts directly as an oxidant in the cathodic reaction of corrosion. The hydrogen evolution reaction rate on the pure copper surface is relatively low in comparison with the polarization measurements on pure iron and platinum.