The in situ natural radionuclide (U-238,Th-232 and(40)K) concentrations in Gumuhane granitoids: implications for radiological hazard levels of Gumuhane city, northeast Turkey

Abstract

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