抄録
The vitrified high-level radioactive waste from reprocessing spent fuels is planned to be disposed of within a stable geological environment at least 300m below ground surface. The evaluation of the individual dose rate caused by the waste to the biosphere is the primary issue for evaluating the safety of geological disposal. The radionuclide dissolution behavior from the vitrified waste is an especially critical processes for calculating the dose rate. The dissolution model proposed by Japan Nuclear Fuel Cycle (JNC, now JAEA) in the second progress report (H12 report)(JNC, 1999) has been used in Japan. However, various dissolution models have been proposed by researchers and implementers since the H12 report. This paper presents the recent progress of the glass matrix dissolution research and identifies four issues of the dissolution behavior of radionuclides. The four issues are as follows: A) "Identification of alteration rate acceleration mechanism and conditions", B) "Investigation into the protective nature of glass alteration layers", C) "Model development for potential disposal environments", and D) "Investigation into the effective surface area".
