Leach Rates of High Activity Waste from Borosilicate Glass

Abstract

Borosilicate glasses containing actual high-level Savannah River Plant waste were leached in static, distilled water. Leach rates based on ⁹⁰Sr, ¹³⁷Cs, and plutonium analyses were similar: 10⁻⁵ to 10⁻⁶ g of glass/(cm²·day) initially, 10⁻⁷ to 10⁻⁸ g/(cm²·day) after two weeks, and 10⁻⁸ to 10⁻⁹ g/(cm²·day) after 100 days. The leach rates were not directly correlated with waste composition, but were qualitatively related to the tendency of the glass to devitrify that could be caused by certain combinations of waste components. According to a proposed model, leach rates were diffusion-controlled during the entire 100-day test.