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Kawamura, Makoto; Yasue, Kenichi; Niizato, Tadafumi; Tokiwa, Tetsuya; Ebashi, Takeshi; Oi, Takao; Makino, Hitoshi; Ishimaru, Tsuneari; Umeda, Koji
Proceedings of 2008 East Asia Forum on Radwaste Management Conference (2008 EAFORM 2nd Conference) (USB Flash Drive), 6 Pages, 2008/10
Japan Atomic Energy Agency (JAEA) had developed a framework to assess the potential impact of natural phenomena (uplift and denudation/climatic and sea-level changes; earthquakes and faulting; volcanism) on a high level radioactive waste (HLW) disposal system as a part of the total system performance assessment. The framework is focused on identifying key T-H-M-C-G (Thermal-Hydrological-Mechanical-Chemical-Geometrical) process associated with potential changes of the geological environment caused by natural phenomena. By using the framework, we could grasp the relationship between characteristic of natural phenomena and geological environmental conditions (T-H-M-C-G) quantitatively, and grasp the relationship between T-H-M-C-G condition and parameters of performance assessment efficiently. In this paper, we tried to develop perturbation scenarios of uplift and denudation by using the framework. As a result, by applying this framework, we could not only grasp the impacts on the geological environmental conditions (T-H-M-C-G) quantitatively, but the excess and deficiency of information resulting from uplift and denudation.
Ishimaru, Tsuneari; Niwa, Masakazu; Kurosawa, Hideki; Kagohara, Kyoko
Proceedings of 2008 East Asia Forum on Radwaste Management Conference (2008 EAFORM 2nd Conference) (USB Flash Drive), 6 Pages, 2008/10
Plate-boundary and intraplate earthquakes occur relative to convergent plate margins in the Japanese Islands. For site selection and design of HLW repositories in Japan, an assessment of the effects of earthquakes and faulting on the deep geological environment is absolutely essential. As a results, it has been determined that consideration of seismic shaking and frictional heating may be unnecessary if repositories are located away from active faults. On the other hand, fracturing along faults could result in the development of fracture zones, which could consequently increase permeability. The number of fracture zone decreases significantly at about 500 m away from the fault, based on the case study of the Atotsugawa Fault System. Therefore, understanding changes in character and spatial distribution of fracture zones through studying the history of fault development is important for long-term changes of regional groundwater flow.
Oyama, Takuya; Saegusa, Hiromitsu; Takeuchi, Ryuji; Takeuchi, Shinji; Matsuoka, Toshiyuki
no journal, ,
The Mizunami Underground Research Laboratory (MIU) is now under construction by Japan Atomic Energy Agency (JAEA) in the Cretaceous Toki granite in the Tono area of central Japan. One of the main goals of the MIU project, which is a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes, is to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The conceptual design of the MIU consists of two 1,000 m shafts with circular cross section, and horizontal research galleries at depths of 500 m and 1,000 m. The project is implemented in the three phases: Surface-based Investigation (Phase I), Construction (Phase II) and Operation (Phase III), with a total duration of 20 years. In Phase II, field investigations such as long-term groundwater monitoring, tiltmeter survey, fluid flow tomography and geological mapping have been also carried out in order to develop and revise geological environmental models. This paper describes the current status of Phase II investigations, with a particular emphasis on hydrogeological characterization.