[en] To study the mechanism of the corrosion process of the related materials and to control corrosion process in relation to the nuclear radwaste management, corrosion behavior of iron and carbon steel in groundwater was studied. Effect of bicarbonate ion, which is one of the most abundant species in groundwater, was studied under both air and nitrogen atmosphere. Bicarbonate ion affects the passivation on the surface of iron and carbon steel. Passive films formed on the carbon steel is more stable than that on pure iron. In groundwater, in which very low concentration of bicarbonate ion is contained, passivation does not occur but pitting corrosion was resulted. Inconel 600 and pure Ni were also tested to elucidate the corrosion mechanism. While Inconel 600 and Ni did not involve hydrogen or hydroxide ions during oxidation process, corrosion process of carbon steel involved either hydrogen or hydroxide ions. (Author)