Activation analyses of air in the accelerator vault of LIPAc building by deuteron beam at 5 MeV and 9 MeV

Takahashi, Hiroki  ; Maebara, Sunao; Sakaki, Hironao; Suzuki, Hiromitsu; Sugimoto, Masayoshi

In the IFMIF/EVEDA prototype accelerator, the engineering validation up to 9 MeV is planned by employing the deuteron beam of 125 mA at the BA site in Rokkasho. In the acceleration of deuteron beam, the activation is critical issues, and the analyses as for isotope productions in the air are indispensable for safety assessment. In the air activation, the Ar is the most important for maintenance works in accelerator vault, and the exhaust management has to be established. For this analysis, the experimental data are used as a source term in neutron transportation and the activation analyses for the air in an accelerator vault are performed by PHITS code and DCHAIN code. The neutron flux around the BD due to the deuteron beam of 5 MeV and 9 MeV are evaluated for the current IFMIF/EVEDA Accelerator design, and it is found that maintenance works cannot be started immediately after deuteron beam operation.