| Abstract Scope |
The precipitation of zeolite has been linked to a delayed acceleration in nuclear waste immobilization glass corrosion (Stage III). Here, we compile a unified thermodynamic database to estimate the stability of secondary phases (including zeolites, clays, and CSH phases). Based on this, we report a geochemical model to predict the stability of secondary phases upon the dissolution of glasses. This approach offers a realistic description of the stability of the secondary phases forming during the dissolution of the International Simple Glass as a function of temperature and pH. We find that the formation of silica and clay secondary phases is thermodynamically favored at low pH (pH < 10), whereas zeolite and CSH phases are favored at high pH (pH > 10.5). This suggests that thermodynamics (not solely kinetics) plays a key role in determining the range of pH wherein stage III corrosion may occur, i.e., when zeolite formation is favored. |