Vitrification of an intermediate level Magnox sludge waste

A novel iron containing alkali alkaline earth borosilicate glass has been developed that can vitrify up to 30 wt% (dry weight) of a Magnox sludge waste in a homogeneous wasteform at a melting temperature of 1200C. Ce was used as a simulant of the actinide content in the waste. The waste was spiked with 0.5wt% of Cs2O of which 90% was retained in the glass. 60% of the Cl was also retained. Mg content limited the waste loading as loadings in excess of 30wt% led to the formation of forsterite and in some cases CeO2 and MgFe2O4 based spinels. PCT leach testing of the glasses for periods up to 180 days indicated the formation of an amorphous magnesium (alumino-)silicate hydrated layer on the glass surface together with barium rich crystalline precipitates. No Ce was detected in the leachate.