Assessment of natural radioactivity in commercial granites used in Turkey

The activity concentrations of 226Ra, 232Th and 40K in twelve different domestic and imported tiling rocks (granites) used as building materials in Turkey were determined by employing high-resolution γ-ray spectrometry. The samples were evaluated to assess the radiation hazard for people by comparing the results with the control values recommended by the European Commission. The measured activity concentrations ranged from 7 to 136 Bq kg−1, 9 to 138 Bq kg−1 and 541 to 1277 Bq kg−1 for 226Ra, 232Th and 40K, respectively. Applying dose criteria recommended by the European Commission[15], two of the samples showed higher Raeq values than the limit dose of 370 Bq kg−1, equivalent to a γ-dose of 1.5 mSv y−1. The calculated gamma-index (Iγ) values for all the 12 samples were lower than the recommended dose criterion. In some of the samples; however, the Hex and Hin values were more than unity. The absorbed dose rates (D) for all the samples, except for four samples, were located within the range values recommen...