PNNL

Abstract

A critical component is determining the suitability of disposing glassified, low activity waste is the identification of key mineral assemblages affecting the porosity and permeability of both the glass and near- and far- field materials. In this study, two different classes of geochemical models are used to identify minerals percipitation and dissolution potentials for an immobilized low-activity waste (ILAW) disposal facility in Hanford, Washington. The first is a static geochemical model that does not consider the effects of transport. The second model is dynamic, and combines geochemical reactions with hydrogeological processes such as advection, diffusion and dispersion. This reactive transport model also includes an innovative application of a depositional film model for determining changes in permeability due to mineral precipitation and dissolution reactions. Although both models describe solid-aqueous phase reactions kinetically, the two models identify two different sets of mineral assemblages affecting the porosity and permeability of the media.