Selection of Glasses in Support of the Sludge Batch 9 Sulfate Solubility Limit for Coupled Operation with the Salt Waste Processing Facility
For Sludge Batches 3 through 8, the sulfate (SO 4 2- )solubility limit for the Defense Waste Processing Facility (DWPF) has been determined by laboratory-scale crucible testing. In preparation for Sludge Batch 9 (SB9) processing, a comparison demonstrated that minor compositional differences existed between the Sludge Batch 8 (SB8)-Frit 803 and SB9-Frit 803 glass composition regions for sludge-only and coupled operations with the Actinide Removal Process (ARP) and Modular Caustic Side Solvent Extraction Unit (MCU). Thus, no experimental testing was necessary and the SB8 SO 4 2- limit of 0.65 wt.% was recommended for SB9 processing. This previous SB9 assessment did not address coupled processing with streams from the Salt Waste Processing Facility (SWPF), which is anticipated to start operations in November 2019. These high activity streams will include monosodium titanate (MST) and sludge solids from the Sludge Solids Receipt Tank (SSRT) as well as Cs-containing strip effluent (SE). The incorporation of these SWPF streams is expected to reach TiO 2 concentrations in glass greater than 2 wt.% based on single and double MST strike scenarios. In support of coupled operation with SWPF, the DWPF Product Composition Control System was revised and allows a TiO 2 concentration of up to 6 wt.% (minus measurement uncertainty) in glass. For the SB8-Frit 803 SO 4 2- solubility study, the maximum TiO 2 concentration evaluated was 0.94 wt.%. Since the influence of increased TiO 2 on the retention of SO 4 2- in the SB9 glass region is unknown, a test matrix of ten glass compositions has been proposed to determine whether the 0.65 wt.% SO 4 2- limit is still appropriate for SB9 coupled operation with SWPF. This report documents the development of a test matrix that will support this study.