Air filtration system for monitoring surface air pollution by man-made radionuclides

A filtration device was constructed allowing effective sampling of surface air for further gamma spectrometric analysis. The working surface of the device is 0.5-1 m2, the capacity being 1800-4400 m3 per hour ±3.6%. The features of the device are illustrated by gamma spectrum of an aerosol sample obtained by using a spectrometer with Ge(Li) detector. Activities of 10-5 Bq.m-3 are determined with high degree of confidence. The very well pronounced pick of Be-7 could be considered as a measure of a high sensitivity and effectiveness of the air-filtration system. The cylindrical geometry of the measurements contributes also for the small value of errors. 30 minutes up to 1 hour is the time needed to get a sample with activity sufficient for obtaining reliable data. Results for daily variations of Be-7 concentration as well as for activities of Cs-134 and Cs-137 are presented. 3 tabs., 1 fig., 7 refs