Studies on the reconstruction of the concept of rock mass around the tunnel. Fiscal year, 2012 (Contract research)

This report is concerned with research to reconstruct more realistic near-field (NF) concept for the geological disposal. In chapter I, we examined the realistic concept for near-field (NF), including rock mass around the tunnel, particularly based on the nuclide migration scenario. The time-series change of the field was divided into five stages of 0 to IV through the process of geological disposal (Excavation, Operation and Post-closure). Then, for each stage respectively, we examined interaction between environmental factors and extraction of those factors changing the "field." The Goal of this year is to exhaustively set up the state in the realistic "field" by focusing on the space-time cross-section of each stage, especially post-closure stage, and to present the assignment of the next fiscal year. In addition, Japan Atomic Energy Agency is planning to study the re-filling process of repository using the -500m Research Gallery of the Mizunami Underground Laboratory, which leads to the verification of the matters as part of reconstructing practical near-field (NF) concept. And we have discussed over this plan. Our comments on the chapter I were summarized as "note" also. In chapter II, we summarized the study of realistic radionuclide migration scenario in the near-field (NF) in chapter I. In addition, since the Great East Japan Earthquake 2011, the safety paradigm has shifted dramatically. In the reconstruction of realistic near-field (NF) concept, it is necessary to analyze the security matters, which has been becoming unacceptable by society. We also exchange views on such matters. (author)