Much of the DOE-EM HLW currently exists as liquid, sludge or precipitated solids in temporary underground storage tanks. This waste will largely be isolated in a glass host before disposal. Accurate prediction of the performance of a disposal facility therefore requires understanding and control of waste glass corrosion over geologic time-scales. This remains a major challenge because of the very slow reactions that occur between two unstructured media that are far from equilibrium (glass and gel). Additionally, a series of coupled processes occurring at the nexus between water being the solvent and water being a solute are responsible for the overall rate of glass water reactions. It is only possible to understand and control glass corrosion through closely coupled theory, simulation, and experimentation. Improved understanding of the composition/structure effects on these processes would allow for rational design of glass waste forms with predictable long-term performance. The research will be conducted in three projects as shown in Figure 1.
Project G1: Rate-Limiting Mechanism of Glass Corrosion involves modeling and experiments on reference glasses to develop a fundamental understanding of the mechanism and a new kinetic model. The objective is to develop a fundamental understanding of mechanism(s) controlling the alteration of glass in the near-saturated conditions.
Project G2: Composition and Environmental Effects on Glass Corrosion Rate expands the testing of key rate limiting phenomena to determine the impacts of different glass compositions under a range of experimental conditions such as chemical and environmental parameters and glass composition. The scope will focus environmental parameters to those with the strongest impacts on the key mechanism from project G1.
Project G3: Rational Glass Design is focused on using the results from previous projects to develop and test models of long-term performance for use in design of waste glasses. This task will emphasize the development of tools for glass design with limited actual materials design and testing. Additionally, focus will be placed on the use of common approaches from the metals and ceramics teams and the modeling synergistic activities.