Perspectives on Performance Assessment and High-Level Waste Glass in a Geologic Repository

Abstract

ABSTRACTThe design and analysis of waste package and engineered systems for geologic disposal of radioactive wastes are being conducted in most countries with so-called performance assessment models and associated computer codes that solve the governing equations. The models range in complexity from simple 1-D analytical solutions to multidimensional, multicomponent reactive transport models implemented in large computer codes. Borosilicate waste glass is certainly the most studied and probably best understood waste form that has been developed for encapsulating high-level waste. Reasonably good models are available that describe the reaction kinetics and transformation of the glass into a paragenetic sequence of more stable secondary phases. Given the broad range of computational tools and extensive database on glass/water reactions that is available, it is surprising that little progress has been made to link these models and data in a comprehensive performance assessment of waste glass in a repository setting. In this paper, we will explore reasons why this linkage has not been developed, give several examples illustrating the importance of doing so, and illustrate an approach to accomplish such a linkage.