Techniques for personnel radioisotope monitoring and its protection

Personnel monitoring aims to evaluate the dose exposed to a worker and confirm the safety of works as well as to improve the working conditions and processes. Here, the present status of personnel monitoring and protective methods for radioisotopes was summarized in respect of tritium. The remaining percentage of tritium in the body, i.e., biological half life varies depending on its chemical form incorporated. When HTO and HT incorporated into the body are mixed into its internal water, they quickly reach an equilibrium and thereafter the tritium levels of the expired air, saliva and urine were found almost consistent over 50 days. Therefore, it was possible to determine the personnel's tritium level by using these specimens the expired air and saliva have little quenching effects and so, liquid scintillation counter was usable for the determination, whereas for urine, previous treatment to remove the quenching substance in it was needed. As a protector for tritium pollution, specific airline suits and groves have been developed using the materials poorly transmissive for tritium. Polyvinylidene chloride for plastic membrane and butyl- or nylon-butyl rubber membrane are used as those materials. The protection coefficients of Mark 3 suit made in Canada and JET made in Europe were evaluated to be 1000 and 3500, respectively. (M.N.)