Effect of composition and temperature on the properties of High-Level Waste (HLW) glasses melting above 1200{degrees}C (Draft)

Abstract

Increasing the melting temperature of HLW glass allows an increase of waste loading (thus reducing product volume) and the production of more durable glasses at a faster melting rate. However, HLW glasses that melt at high temperatures differ in composition from glasses formulated for low temperature ({approximately}1150{degree}C). Consequently, the composition of high-temperature glasses falls in a region previously not well tested or understood. This report represents a preliminary study of property/composition relationships of high-temperature Hanford HLW glasses using a one-component-at-a-time change approach. A test matrix has been designed to explore a composition region expected for high-temperature high-waste loading HLW glasses to be produced at Hanford. This matrix was designed by varying several key components (SiO{sub 2}, B{sub 2}O{sub 3}, Na{sub 2}O, Li{sub 2}O, Fe{sub 2}O{sub 3}, Al{sub 2}O{sub 3}, ZrO{sub 2}, Bi{sub 2}O{sub 3}, P{sub 2}O{sub 5}, UO{sub 2}, TiO{sub 2}, Cr{sub 2}O{sub 3}, and others) starting from a glass based on a Hanford HLW all-blend waste. Glasses were fabricated and tested for viscosity, glass transition temperature, electrical conductivity, crystallinity, liquidus temperature, and PCT release. The effect of individual components on glass properties was assessed using first- and second- order empirical models. The first-order component effects were compared with those from low-temperature HLW glasses.