Determination of natural radioactivity by gross alpha and beta measurements in tap waters in Rize province

The aim of the study to determine the level of gross alpha and beta activity concentrations in tap waters in dwellings of Rize province from North part of Turkey after 27 years from Chernobyl disaster. The activity concentrations of gross alpha and beta were ranged from 5 to 164 mBq L-1 with a mean of 22 mBq L-1 and from 12 to 787 mBq L-1 with a mean of 85 mBq L-1 respectively. In addition to activity concentrations, the annual effective doses were calculated. The results indicated that the effective doses were below the WHO recommended level of 100 A mu Sv year(-1) for the samples.