Radiogenic Heat Production from 238U, 232Th, and 40K in Soil and Heat Effect on Radon Exhalation Rate

Abstract

      In this study, thirty soil samples were collected from Al-Qasim district in Babylon city, Iraq, and were prepared, analyzed, and evaluated to calculate the concentration of ²³⁸U, ²³²Th, and ⁴⁰K concerning their radiogenic heat production using a NaI (Tl) gamma spectroscopy detector. The results show that ²³⁸U and ²³²Th are the prevalent radionuclides in radiogenic heat production, with ⁴⁰K emerging as a trace element. The concentration of ²³⁸U, ²³²Th, and ⁴⁰K% (ppm) in soil samples was with an average of 1.584, 6.996, and 0.754, respectively. The mean radiogenic heat production rate, R_H, and A_g are 0.957 and 0.977 μW.m^-3, respectively. The radionuclide contributions to radiogenic heat production at all sampled locations are 42.3 %, 50 %, and 7.7 % for uranium, thorium, and potassium, respectively. All values obtained for this study are lower than the average continental radiogenic heat production of 1 μW.m^-3. Therefore, the study area can be classified as a region with low heat production, which indicates that the study area does not hold oil and gas reserves. Additionally, the radon concentration was 87.267 Bq/m³, and its mass exhalation rate was 0.007 mBq/kg/h. In contrast, the results indicated that the radon mass exhalation rate increases as the temperature rises. This study provided insight into the radiogenic heat production rate resulting from the presence of radionuclides in all soil samples.