Effects of some glass additives on nuclear waste glass durability in water

Borosilicate glass is a candidate material for immobilizing high-level waste (HLW) stemming from the reprocessing of spent fuels used for nuclear power generation. The borosilicate glass containing HLW, which is called HLW glass, will be stored on the land surface for several tens of years and then disposed of in deep geologic formations. The contact of HLW glass with ground water in deep geologic disposal sites is the primary concern of this paper, because it is a first step for radionuclides in the glass to be released into the biosphere. The durability of HLW glass in ground water is fairly good for the purpose of safe disposal. However, if the leach rate of the HLW glass is reduced by four orders of magnitude to 10 .9 g cm -2 day -1, the glass can hold its integrity even after a considerable amount of 237Np with a half-life of 2.14 × 106 years decays in the glass. In this study, we try to improve the durability of the glass as much as possible. For this purpose, the effects of some glass additives on nuclear waste glass durability in water are examined. For example, Fe203 is used as a glass additive, since it has been