Research on release of tritium and iodine formed in mercury to gas-phase

Yokoyama, Sumi; Manabe, Kentaro   

At Material and Life Science facility of J-PARC, a mercury target as spallation neutron source is used. In the mercury target, airborne radionuclides such as tritium and iodine are formed by spallation reaction with high energy and intensity proton beam. There is possibility that the airborne radionuclides leaked from the target vessel to the air of the facilities may cause internal exposure. However, there is insufficient information about these chemical forms and behavior in mercury to estimate internal doses. We clarified chemical forms and release rates of tritium and iodine from mercury by experiments and discussed from the viewpoint of internal radiation protection. In this study, we found that most tritium formed in mercury is released to the gas-phase as HTO, while iodine is not released under the condition of gas phase in the mercury target.