Applicability of V2O5-P2O5 glass system for low-temperature vitrification

The V2O5-P2O5 glass system (vanadate glass) has been developed to provide low temperature vitrification of radioactive waste without volatilization of radionuclides. The dissolution behaviour of vanadate glass was determined from the results of the MCC-1 static leach test at 70 degrees C using deionized water, cement-saturated alkaline water, and cement-saturated alkaline water with 3% NaCl. The solubility of vanadate glass was remarkably reduced by the addition of Sb2O3 to the glass. It was also lowered in the cement-saturated water due to formation of a precipitation layer. Although the presence of NaCl in the solution accelerated the dissolution of vanadate glass, the addition of alkaline earth metal oxide to the glass gave a dissolution rate three orders lower than non-additive vanadate glass. The results of leach tests using simulated vitrified waste form containing 5mol% of Cs2O and SrO showed there was a possibility of fixing Cs and Sr into the glass structure.