Estimation of NORM in Local and Imported Granite used as Building Materials in Tunisia

Measurements of natural radioactivity in local and imported samples of commercial granites used in Tunisia were carried out by using gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured of granite samples were determined for 226Ra (from 0.54 to 90.12 Bq.kg−1), 232Th (from 0.47 to 128.36 Bq.kg−1) and 40K (from 14.36 to 1792.08 Bq.kg−1). The corresponding average activity concentrations for 226Ra, 232Th and 40K were 36.70, 62.16 and 1068.40 Bq.kg−1, respectively. The radiological hazard parameters (radium equivalent, gamma index, external hazard index, internal hazard index, absorbed dose and annual effective dose) were calculated to assess the radiation hazards associated with granite samples. The annual effective dose values ranged from 0.01 in the sample (S1) to 1.8 mSvy−1 in the sample (S9). The international upper limit annual effective dose of 1 mSvy−1 is exceeded in some granites samples.