Degradation of high-level waste glass under simulated repository conditions

The internal waste package environment that contains corrosion products from the containers may have a significant influence on waste form degradation. Leaching experiments of two simulated high-level waste glasses (WVDP Ref. 6 and DWPF Blend 1) were carried out in aqueous solutions of FeCl2 and FeCl3 at temperatures of 40, 70, and 90 °C that simulate the possible aqueous environment inside the breached waste packages. Both solution pH and the presence of corrosion species such as iron chloride were found to be major contributing factors to the net glass durability. Model abstraction and performance assessment analyses using rate expressions showed that the presence of corrosion products enhances glass dissolution and increases the subsequent release of radionuclides to the environment.