Cold Crucible Vitrification of SRS SB4 Waste at High Waste Loadings

Abstract

The test on determination of maximized waste loading was performed at the Radon bench-scale facility equipped with a 236 mm inner diameter cold crucible. Waste surrogate was vitrified using a commercially available Frit 503-R4 (in wt.%: 8 Li2O, 16 B2O3, 76 SiO2). Waste loading ranged between ∼45 and 70 wt.%. Viscosity of the melt with 50 wt.% waste loading remained lower that 100 Poise (maximum value for glass melting) even at temperatures below 1300 °C. Electric resistivity value for this glass allowed electric melting at temperatures of 1100–1150 °C and higher. Melt viscosity increased with the increase of waste loading and glass with 60 wt.% waste loading had appropriate viscosity for melting at temperatures over 1350 °C. This glass was much “shorter” than the glass with 50 wt.% waste loading. Its electric resistivity at the same temperature was higher than that of glass with 50 wt.% waste loading and allowed this glass to be produced at temperatures 1250 °C and lower, but the high viscosity was a restricting factor and this glass required temperatures ∼ 1400 °C and over to be produced. The melt with 70 wt.% waste loading was too inhomogeneous and viscous and its viscosity and electric resistivity could not be measured precisely. As a result the glasses with 70 and 60 wt.% waste loadings required melting temperature as high as 1350–1400 °C whereas the glass with 50 wt.% waste loading may be produced at 1150–1250 °C. Wet slurry (∼50 and ∼70 wt.% water content) in the amount of 625.1 kg was processed and glass in the amount of 186.6 kg was produced and poured into 12 canisters for 91 hrs. Average slurry feed rate, glass productivity and specific glass productivity were 6.86 kg/hr, 2.16 kg/hr, and 68.8 kg/(m2xhr) respectively.