Tono Geoscience Center (TGC), Japan Nuclear Cycle Development Institute (JNC) has been carrying out a wide range of geoscientific researches in order to build a firm scientific and technological basis for the research and development of geological disposal. One of the major components of the ongoing geoscientific research program is the Mizunami Underground Research Laboratory (MIU) Project in the Tono area, central Japan. The R & D work of the MIU Project has the following main goals :

- Establish comprehensive techniques for investigating the geological environment;
- Acquire data on the deep geological environment;
- Develop a range of engineering techniques for deep underground application.

The development of the MIU will occur in three overlapping Phases over a 20-year life cycle: Phase I : Surface-based investigations, began in 1996; Phase II : Construction; and Phase III : Operations, have yet to start.

The Shobasama site has been investigated by geological, geophysical, hydrogeological, hydrochemical and rock-mechanical investigations on the ground surface and in the boreholes. Ground geophysical explorations and borehole investigations (three 1,000m-class boreholes) have been carried out so far. Besides, pore pressure monitoring equipment has been set up. Based on the information, geological, hydrogeological models and rock mechanics conceptual model have been constructed. Groundwater flow simulation has been carried out in order to verify the validity of hydrogeological modeling methodology. These investigations and researches have facilitated to accumulate technical knowledge and experience on methodologies and techniques to characterize the deep geological environment.

The results of the R&D activities not only are reflected to the H12 report submitted by JNC to the Japanese Government in 1999, but have been also widely utilized by various research institutes, including universities. JNC will further researches to provide scientific and technological base for the safety regulation and the repository siting.