The leaching of radioactive waste storage glasses

Results are reported of leach tests on various glass compositions proposed for the vitrification of the highly radioactive waste from the reprocessing of Magnox fuel. It is shown that the leach rate falls rapidly with temperature, decreasing by two orders of magnitude between 100 and 00C. There is comparatively little difference between the leach rates in various natural waters but the Soxhlet apparatus gave values about three times higher than those found in static tests. Acidic solutions gave markedly increased leach rates: alkaline solutions also increased the leach rates under some conditions but to a lesser extent. Leach tests on plutonium containing glasses showed that this element was preferentially retained by the glass. The effect of α and β radiation on the leach rate was shown to be small. (author)