The in situ natural radionuclide (²³⁸U,²³²Th and⁴⁰K) concentrations in Gümüşhane granitoids: implications for radiological hazard levels of Gümüşhane city, northeast Turkey

We have carried out 48 in situ measurements on radioactivities of ²³⁸U, ²³²Th and ⁴⁰K isotopes at the Gümüşhane granitoid plutons employing gamma-ray spectrometer with a NaI(Tl) scintillation detector. The radionuclide activity concentrations of ⁴⁰K, ²³⁸U and ²³²Th ranged from 62.6 to 1680.8 Bq kg⁻¹, 2.5 to 119.9 Bq kg⁻¹ and 3.3 to 92.4 Bq kg⁻¹, respectively. The mean concentration of natural radionuclides (⁴⁰K, ²³⁸U and ²³²Th) was found to be 638.5 ± 421.6 Bq kg⁻¹, 40.8 ± 27.4 Bq kg⁻¹ and 33.5 ± 25.5 Bq kg⁻¹, respectively. The mean values of the radium equivalent and the external hazard index were 137.9 ± 80.6 Bq kg⁻¹ and 0.37 ± 0.22, respectively. The value of annual effective dose equivalent value (81.8 μSv year⁻¹) is lower on average than in the world average of 460 μSv year⁻¹. The external hazard index acquired in this study did not exceed the international safety standard levels, which means that Gümüşhane pluton does not produce any radiation hazards to the dwellers.