Pressure dependence of glass dissolution and nuclear waste disposal

Abstract

Schemes to dispose of high-level radioactive waste by vitrification and subsequent burial call for an appraisal of the consequences of groundwater encountering the waste glass¹. Glass dissolution rates are influenced not only by properties of the glass and solvent themselves but also by properties of the combination such as the glass surface area to solvent volume ratio². Although pressure may affect glass dissolution rates, it has not received unambiguous explicit experimental investigation. A simple experiment has been designed to determine dissolution rates at room temperature of glass samples subject to very high pressure in a centrifuge. The results reported here show that the dissolution rates for Na and Si increase slightly with pressure, but that at a pressure of 160 MPa (>1,500 atm) these dissolution rates are still of the same order as those at atmospheric pressure.