Modeling the Evolution of a Soluble Matrix in Various Environments

Abstract

ABSTRACTWe model the dissolution of a soluble matrix protected by a diffusion barrier. The dissolution, driven by a first order kinetics law, allows the solute to diffuse in the barrier with sorption and precipitation interactions. The dissolved mass evolution and the lifetime of the wasteform can be expressed in a closed form and as a function of relevant length scales, reflecting the phenomenon controlling the dissolution. Application to a nuclear glass in a clay barrier shows that diffusion in the barrier is the main phenomenon unless precipitation of chalcedony occurs or silicon is very strongly sorbed in the barrier. This requires further experimental investigation of silicon/clay interaction.