In order to elucidate the hypotheses for the corrosion mechanisms of high-level radioactive waste glass under near-saturation condition, focusing on the characteristics of the alteration later formed at the surface of the leached glass in amorphous silica saturated solutions, pH dependency on the glass corrosion and the corrosion rate limiting diffusion phenomena were investigated. Corrosion rate of the glass icnreased with decrease in solution pH at the pH range of 4.1 - 9.5 and a diffusion layer was formed and grew in the neighborhood of pristine glass- alteration layer interface for the leached glass. These experimental observations are consistant with the hypothesis that ion exchange by proton or H3O+ as well as water diffusion controls the glass corrosion and teh diffusion of mass is teh rate-limitting step under near-saturation condition.
