ACTIVITY SIZE DISTRIBUTION OF NATURAL RADIONUCLIDES

The activity size distributions of the natural radionuclides Be-7, Pb- 210 and K-40 were determined in the open air by means of gamma spectro scopy. Size distributions of the radioactive aerosol particles were de termined by using the low-pressure Berner cascade impactor (Model 20/0 .015) as a sampling device. Moreover, the mass size distribution of th e sampled aerosol particles was also determined. The activity size dis tribution of these radionuclides was described by one log-normal distr ibution (accumulation mode) while the mass size distribution was repre sented by two log-normal distributions (accumulation and coarse mode).