PNNL

Abstract

Roughly half of the projected Hanford high-level waste batches will have waste loadings limited by relatively high concentration of Al2O3. Individual glasses have been formulated and tested to demonstrate that it is possible to increase the loading of these high-Al2O3 wastes in glass by as much as 50%. To implement such increases in waste loading in the Hanford Tank Waste Treatment and Immobilization Plant, the impact of composition on the properties of high-Al2O3 waste glasses must be quantified in the form of validated glass property-composition models. To collect the data necessary for glass property-composition models, a multi-phase experimental approach was developed. In the first phase of the study, a set of 46 glass compositions were statistically designed to most efficiently backfill existing data in the composition region for high-Al2O3 (15 to 30 wt%) waste glasses. The glasses were fabricated and key glass properties were tested: •Product Consistency Test (PCT) on quench (Q) and canister centerline cooled (CCC) samples •Toxicity Characteristic Leaching Procedure (TCLP) on Q and CCC samples •Crystallinity as a function of temperature (T) at equilibrium and of CCC samples •Viscosity and electrical conductivity as a function of T The measured properties of these glasses were compared to predictions from previously existing models developed over lower Al2O3 concentration ranges. Areas requiring additional testing and modeling were highlighted.