CHARACTERIZATION OF VITRIFIED SAVANNAH RIVER SITE SB4 WASTE SURROGATE PRODUCED IN COLD CRUCIBLE

Savannah River Site (SRS) sludge batch 4 (SB4) waste surrogate with high aluminum and iron content was vitrified with commercially available Frit 503-R4 (8 wt.% Li2O, 16 wt.% B2O3, 76 wt.% SiO2) by cold crucible inductive melting using lab- (56 mm inner diameter), bench- (236 mm) and large-scale (418 mm) cold crucible. The waste loading ranged between 40 and 60 wt.%. The vitrified products obtained in the lab-scale cold crucible were nearly amorphous with traces of unreacted quartz in the product with 40 wt.% waste loading and traces of spinel phase in the product with 50 wt.% waste loading. The glassy products obtained in the bench-scale cold crucible are composed of major vitreous and minor iron-rich spinel phase whose content at ∼60 wt.% waste loading may achieve ∼10 vol.%. The vitrified waste obtained in the large-scale cold crucible was also composed of major vitreous and minor spinel structure phases. No nepheline phase has been found. Average degree of crystallinity was estimated to be ∼12 vol.%. Anionic motif of the glass network is built from rather short metasilicate chains and boron-oxygen constituent based on boron-oxygen triangular units