Mizunami Underground Research Laboratory Project; Results of the borehole investigations to understand the geological environment in and around the Main-shaft fault

Tsuruta, Tadahiko  ; Takeda, Masaki ; Ueno, Takashi; Daimaru, Shuji; Tokuyasu, Shingo; Onoe, Hironori ; Shingu, Shinya; Ishibashi, Masayuki; Takeuchi, Ryuji  ; Matsuoka, Toshiyuki; Mizuno, Takashi   ; Tagami, Masahiko*

Tono Geoscientific Research Unit of Japan Atomic Energy Agency (JAEA) is performing the Mizunami Underground Research Laboratory (MIU) project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The borehole investigations (two boreholes; 10MI22 borehole and 10MI23 borehole) have been carried out to obtain information on geological, hydrological and hydrochemical characteristics in and around the Main-shaft fault. These investigations provided that features of fracture and alteration on rock mass in and around the Main-shaft fault. Hydrological and hydrochemical properties based on the geological features were also obtained.