On the turn determination of crush zone activity; A Lesson from granitic basement rock holding the fast breeder reactor "Monju"

Shimada, Koji   ; Tateishi, Ryo*; Ishimaru, Tsuneari ; Sasaki, Akimichi; Tanaka, Yukumo; Miyazaki, Masashi; Yasue, Kenichi; Niwa, Masakazu   ; Sueoka, Shigeru   ; Umeda, Koji; Ikeda, Makinori

Activity evaluation of crush zones encountered in basement rock is an issue of the seismic safety assessment of nuclear plant and geological isolation of radioactive wastes. The selection of crush zone of which has been evaluated should be defined as the latest one by means of turn determination of crush zone activity based on stratigraphic or structural geological method. A lesson from granitic basement rock (Kojaku granite) holding the fast breeder reactor "Monju" is presented. The Kojaku Granite form the oval Tsuruga peninsula (ca. 8km in width) on the southeastern coast of the Sea of Japan and the age is 68.5 plus/minus 0.7Ma (Zircon U-Pb age).1. Stratigraphy-oriented turn determination of crush zone activity. (1.1) Turn determination using cover sediments. (1.2) Turn determination using dyke, mineral and clay vein. 2. Structural-oriented turn determination of crush zone activity.