Dissolution of Borosilicate Glasses under Repository Conditions of Pressure and Temperature

Abstract

The projected style of the UK’s high level radioactive waste disposal program envisages a period of cooling of the vitrified waste form, prior to disposal in a deep repository. The length of time during which the waste blocks must be kept in store depends on many factors, including social and waste management considerations, and on the limiting admissible temperature which may be attained in a final repository. This temperature value, in turn, depends on the maximum thermal load capacity of the total repository system, i.e. the near-field rock matrix, the canister and backfill materials, and the vitrified waste form itself. One of the factors that these load capacities are dependent upon is the hydrothermal behavior of the various components under deep repository conditions; in other words, their ability to resist significant geochemical changes or corrosion by reaction with warm, pressurized groundwaters.