Correlation of radionuclide leachabilities with microstructures of glasses containing Savannah River Plant waste

Leachabilities of cesium and strontium from the glass matrices were correlated with the microstructures of glasses containing waste sludge from two SRP waste tanks. All sludge components, except mercury which volatilized, were completely soluble in the melt, but small amounts of crystalline iron oxide precipitated during cooling. These precipitates were less leachable than the glass matrix. Even though the compositions of the two sludges that were tested were similar, glass containing one of the sludges devitrified during heating at 6000C; glass containing the other sludge did not devitrify. Leachability of the devitrified glass was as much as 100 times greater than that of nondevitrified glass, but still very low, less than 10-6 g/(cm2)