Influence of Great East Japan Earthquake on neutron source station in J-PARC

Sakai, Kenji ; Sakamoto, Shinichi; Kinoshita, Hidetaka   ; Seki, Masakazu; Haga, Katsuhiro  ; Kogawa, Hiroyuki  ; Wakui, Takashi  ; Naoe, Takashi   ; Kasugai, Yoshimi  ; Tatsumoto, Hideki; Aso, Tomokazu ; Hasegawa, Shoichi   ; Maekawa, Fujio  ; Oikawa, Kenichi   ; Oi, Motoki ; Watanabe, Akihiko; Teshigawara, Makoto   ; Meigo, Shinichiro   ; Ikezaki, Kiyomi; Akutsu, Atsushi; Harada, Masahide   ; Takada, Hiroshi   ; Futakawa, Masatoshi  

This report investigates the behavior, damage and restoration of a neutron source station of the MLF at the Great East Japan Earthquake and verified the safety design for emergency accidents in the neutron source station. In the MLF, after an occurrence of the Earthquake, strong quakes were detected at the instruments, the external power supply was lost, all of the circulators shut down automatically, and the hydrogen gas was released. The leakages of mercury, hydrogen and radio-activation gases did not occur. While, the quakes made gaps between the shield blocks and ruptured external pipe lines by subsidence around the building. But significant damages to the components were not found though the pressure drop of compressed air lines influenced on a target trolley lock system and so on. These results substantiated the validity of the safety design for emergency accidents in the source station, and suggested several points of improvement.