Comparison of Nuclear Waste Glass Leached in Natural Groundwater at 14°C with That in Synthesized Groundwater at 70°C

Abstract

High-level waste (HLW) glass which contains hazardous fission products and actinides should be isolated from the biosphere. One isolation method is disposal in geologic formations. The contact of groundwater with the HLW glass will be a trigger for waste radionuclides to move into the biosphere. Therefore an extensive study of the leaching behavior of HLW glass in groundwater is necessary.The in-situ burial leach tests carried out in Japan provided several results on leaching behavior of simulated HLW glass in natural groundwater. For example, uneven leaching occurred in natural groundwater, which resulted in the formation of many grooves on the originally flat surface of the glass(1)(2). This result was found in an experiment carried out at a low temperature of 14°C, and we have not yet confirmed whether or not such uneven leaching occurs at relatively higher temperatures.In the present study, we showed that the leaching behavior of simulated HLW glass at 14°C in one type of natural groundwater in Japan was quite similar to that which occurred at 70°C in the synthesized groundwater in two ways ; uneven leaching and precipitation.