PNNL

Abstract

The objective of the EC funded GLAMOR project was to achieve a common understanding of the processes that control the decrease of the dissolution rate of high-level waste glass in water when silica becomes saturated. Is the affinity controlled concept, or the protective layer concept dominating? The following steps were taken: (1) review of the literature, (2) selection of an experimental dataset, and selection of the models r(t) and GM2003, and (3) application by the GLAMOR partners of the models to the datasets. The main focus has been on dissolution tests in pure water at different values of surface to volume and pH. Some of the main conclusions were: (1) both affinity and protective layer concepts must be considered in the interpretation of the rate decreasing stage, (2) the residual dissolution rate observed beyond the silica saturation stage is far more important in view of the long-term performance of the glass, and deserves more attention in future R&D. GLAMOR also discussed in detail the modelling parameters such as the silica saturation concentration, the silica diffusion coefficient, the silica retention factor in the reaction layer, and the water diffusion coefficient.