Experiences on radioactivity handling for mercury target system in MLF/J-PARC

Kai, Tetsuya   ; Kasugai, Yoshimi  ; Oi, Motoki ; Kogawa, Hiroyuki  ; Haga, Katsuhiro  ; Kinoshita, Hidetaka   ; Seki, Masakazu; Harada, Masahide   

Neutrons are produced by an intense proton beam (1 MW) irradiation on a mercury target in the Material and Life science experimental Facility of J-PARC. The proton beam irradiation produces various kinds of radioactivity via the spallation reaction of mercury. Design of radioactivity treatment was carried out based on estimation by using particle transport calculation codes NMTC/JAM, MCNP/4C and an induced radioactivity calculation code DCHAIN-SP 2001. This presentation shows how the estimation being utilized in design of a mercury circulation system and an off-gas processing system as specific examples. In addition the authors report some knowledge mainly about behavior of xenon and tritium obtained in operation. This presentation includes important lessons about treatment of spallation products. Thus the lessons are expected to be fully utilized in discussions of future accelerator driven neutron sources and transmutation systems using liquid metal as target material.