Status and subject of investigation and construction at Mizunami Underground Research Laboratory, 1

Sato, Toshinori  ; Takeuchi, Shinji; Mikake, Shinichiro ; Sugihara, Kozo

The Mizunami Underground Research Laboratory, one of the main facilities in Japan for research and development of the technology for high-level radioactive waste disposal, is being constructed in Mizunami City. By October 2005, the excavation of the Main and Ventilation Shafts had reached depths of 172m and 191m, respectively. However, shaft sinking was then suspended for about 6 months due to high concentrations of boron and fluorine in the inflow water in the shafts, which exceeded the environmental discharge limits. To resolve this problem, an additional effluent treatment system was adopted, and shaft sinking restarted in April 2006. Pilot boring investigations were performed at the both shafts. This report shows the status and subject of investigations and construction of Mizunami Underground Research Laboratory.