Radioactive element contents of some granites used as building materials: insights into the radiological hazards

This study was conducted to investigate the radioactive potential hazard of granite, which is widely used as building material in Turkey. Natural radiation levels of 18 various, globally-distributed industrial granite samples imported by Turkey, were analyzed using gamma-ray spectrometer. The results are compared with the formerly published findings of granite samples from Turkey. Radioactivity levels of ²³⁸U, ²³²Th, and ⁴⁰K natural radioactive series elements of the selected 18 specimens were measured, which were from 2.4 ± 0.5 to 88.8 ± 3.6 Bq kg⁻¹ for ²³⁸U, from 2.4 ± 0.7 to 273 ± 0.9 Bq kg⁻¹ for ²³²Th, and from 169 ± 24 to 1,479 ± 94 Bq kg⁻¹ for ⁴⁰K. Radium equivalent activities (Ra_eq) were calculated for the granite samples to assess their radiation hazards in the construction of dwellings. The Ra_eq values of granite samples varied in the range of 39.05–570 Bq kg⁻¹, only one sample exceeded the safe limit value of 370 Bq kg⁻¹ set by the OECD-NEA (Nuclear Energy Agency. Exposure to radiation from natural radioactivity in building materials. Report by NEA Group of Experts 1979). Absorbed dose rates in air were found between 18.74 and 261 nGy h⁻¹ and radiogenic heat production values were calculated in the range of 0.45–6.53 μW m⁻³. All rock samples used in this study were also analysed mineralogically and defined their compositions.