Natural radioactivity in drinking water treatment plant

Concentrations of 226Ra and Unat were measured in treated water in a drinking water treatment plant in an area of the Central Bohemian region which has a higher than elsewhere concentration of natural radionuclides in mineral rocks. The concentrations ranged between 34 and 674 mBq/l for 226Ra and from 1.2x102 to 6.54x102 μg/l for Unat. The annual intake of 222Rn daughters in the ambient air of the treatment plant per operator was 11.8x1010 MeV in 1983 and dropped to 2.69x1010 MeV in 1984 after the installation of an air exhaustion system above the plant's storage reservoir. In nine random selected appartments supplied with water from the treatment plant the average concentration of 222Rn daughters was found to be 390 MeV/l in the rooms, by several hundred MeV/l higher in the bathrooms. The concentrations did not, however, exceed 1000 MeV/l. (author). 4 tabs., 4 refs