Glass formulation and lab-scale testing of glasses designed for in-can Melter and in-container Vitrification of high-assay low-enriched uranium aqueous polishing Raffinate waste

Abstract

Glasses were designed for processing a nuclear waste from aqueous polishing of high-assay low-enriched uranium using either In-Can Melter or GeoMelt® In-Container Vitrification™ (ICV) technologies, which operate at temperatures of Tp ≤ 1100 °C and Tp ≤ 1450 °C, respectively. Due to the different operating conditions, the melt and glass properties were optimized differently for each technology. Each glass was designed to optimize for maximum waste loading while simultaneously satisfying processing (e.g., crystallization, viscosity, conductivity) and product quality (e.g., durability, hazard characteristic, crystal content) constraints. The raffinate waste contains high nitric acid (4 M) and low total solids (9 g∙L−1) concentrations. Feed preparation processes were tested to facilitate concentration and nitrate destruction/removal while controlling redox of the melter feed. A successful lab-scale feed process including sugar addition and spray-drying was performed to generate an adequate melter feed for ICV processing.