Core message from PNC/H-3 and key issues for the next milestone

The PNC/H-3 is the first progress report on the research and development of HLW geological disposal in Japan. This paper describes on overview of the performance assessment studies in the H-3 report and critical issues identified through the studies. Subsequently, the outline of the PNC's study plan for the post H-3 stage is introduced. The generic performance assessment studies in the H-3 report indicated that the performance of a massive engineered barrier system could be sufficient within a range of likely geological conditions in Japan. Sensitivity studies of the performance of the natural barrier system coupled with the strong engineered barrier indicated the importance of the investigation of geological barrier effects in the near-field. Studies in the H-3 indicated that the research approach which placed an emphasis on the near-field analyses was promising to confirm the technical feasibility of the HLW geologic disposal concept in Japan. In order to make the approach more promising and effective it is important to promote more detailed and comprehensive analyses of the near-field processes. The PNC's research and development of post H-3 stage before the year 2000 is focused on the detailed analyses of the near-field. A set of engineering scale laboratory experiments and in situ experiments at Tono and Kamaishi mines will play an important role for the post H-3 studies