Hydrogeological Characterization on Surface-Based Investigation Phase in the Mizunami Underground Research Laboratory Project, in Japan

Abstract

The Mizunami Underground Research Laboratory (MIU) project is being carried out by Japan Atomic Energy Agency in the Cretaceous Toki granite in the Tono area, central Japan. The MIU project is a purpose-built generic underground research laboratory project that is planned for a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes. One of the main goals of the MIU project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. The MIU project has three overlapping phases: Surface-based Investigation (Phase I), Construction (Phase II) and Operation (Phase III). Hydrogeological investigations using a stepwise process in Phase I have been carried out in order to obtain information on important properties such as, location of water conducting features, hydraulic conductivity and so on. Hydrogeological modeling and groundwater flow simulations in Phase I have been carried out in order to synthesize these investigation results, to evaluate the uncertainty of the hydrogeological model and to identify the main issues for further investigations. Using the stepwise hydrogeological characterization approach and combining the investigation with modeling and simulation, understanding of the hydrogeological environment has been progressively improved.

What does hydraulic tomography tell us about fractured geological media? A field study and synthetic experiments

“…A detailed description of the general geology of the MIU site can be found in Saegusa and Matsuoka (2011) and Illman et al (2009). As indicated in Fig.…”

Excavation cycle times recorded during sinking of a deep shaft in crystalline rock – A case example at Ventilation Shaft of Mizunami URL, Japan

“…Excavation of the Ventilation and Main Shafts reached GL-500 m in FY2011. During Phase I, the design work for surface and underground facilities in the MIU was completed with the aim of providing a foundation for engineering technologies to safely construct and operate a deep underground facility built for the purpose of data acquisition and demonstrating disposal technologies (Saegusa and Matsuoka, 2011). The design work incorporated development of Ect estimates prior to MIU construction as a basis for estimating overall costs and schedule requirements for the proper operating management of the MIU.…”

“…The MIU is being developed and operated in three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III) with a total duration of around 20 years. The overall project goals of the MIU Project in Phases I through III are: (1) to establish techniques for investigation, analysis and assessment of the deep geological environment and (2) to develop a range of engineering technologies applicable to deep underground environments in Japan (Saegusa and Matsuoka, 2011).…”

Ground Subsidence Following Groundwater Drawdown by Excavating of 500 m Deep Investigation Shafts in Granite Body in Mizunami, Central Japan in 2004-2012

“…The Miocene Mizunami Group, including lignite-bearing formation in the lowermost part covers inconsistent with the Toki granite complex in excavating the area [12]. Before the excavating, it is suggested the boundary depth of the Toki granite complex and Mizunami Group [8] and regional ground water flow system based on the 100 m deep boring logging, airborne electromagnetic survey, gravity survey, and elastic wave exploration. As results of the excavating, plane of the unconformity is about 200 m deep.…”

“…Japan Atomic Energy Agency (JAEA) conducted Mizunami Underground Laboratory (MIU) Project in Mizunami, which is a comprehensive research project investigating the deep underground environment within crystalline rock. The project role is defined in "Framework for Nuclear Energy Policy" by Japan Atomic Energy Commission [8]. The project is ongoing under the agreement of no installation of radioactive-waste and no waste-disposal site in future associated with the lease contract for the Mizunami City-owned land [9]- [11].…”