Monitoring techniques for radioactivities in environment

The present status of the monitoring systems for environmental tritium was summarized in this report. Generally, natural water, organisms and the air are used as the test subjects for environmental monitoring. In these subjects, the tritium levels are ordinarily very low. Therefore, an electrolytic concentration method with alkaline solution has been used for its concentration. Recently, solid polymer electrolyte method using cation exchange resin membrane (SPE method) has been developed and a specific automatic apparatus for SPE method is obtainable in the market. This method is more reliable and safety with no generation of detonating gas compared with the previous one. The determination of tritium level is conducted by liquid scintillation counter, which is satisfactorily sensitive for tritium levels in the environment. Also, it is desirable to determine the trace tritium by He-isotope method for the comparison with the data from the liquid scintillation method. (M.N.)