Target system maintenance experience in hot cell at J-PARC

Kinoshita, Hidetaka   ; Haga, Katsuhiro  ; Kai, Tetsuya   ; Wakui, Takashi  ; Kogawa, Hiroyuki  ; Teshigawara, Makoto   ; Naoe, Takashi   ; Takada, Hiroshi   

At the J-PARC, a mercury target system has been in operation as a neutron production target of the spallation neutron source driven by 3-GeV protons. It is loaded on a big target trolley (L12 W2.6 H4 m) which moves horizontally on a rail in a hot cell. The volume of the hot cell is as large as L43 W12 H15 m. Target vessel replacement is performed with full-remote handling devices such as a 6-axis power manipulator, 3 pairs of master/slave manipulators, an in-cell overhead 20 t crane and radiation resistant cameras. Since a large amount of radioactive gaseous nuclides are generated in mercury via the spallation reactions, the off-gas processing system is installed in a room nearby the hot cell to transfer the cover gas in a serge tank of the mercury circulation system to the off-gas processing system before replacing target vessel. More detailed design of hot cell and experiences on the target system maintenance will be presented.