Measurement system for alpha and beta emitters with continuous air sampling under different exposure situations

In the present study, a continuous radioactive aerosol measurement system (CRAMS) was developed for measurements of radioactive plume (e.g. 131I, 134Cs and 137Cs) under the emergency situation, and measurements of radon/thoron progeny under the existing situation. As a result, it is suggested that the CRAMS could follow the variation of radon concentration, and the detection limit of the CRAMS under ambient dose equivalent rate of 20 µSv h−1, where the temporary evacuation is required within one week in the Japanese regulation, was evaluated to be 129 Bq m−3 in the manner of ISO11929.