Measurement of exposure to radionuclides (40-K, 226-Ra, and 232-Th) in the oil and gas drilling industry

Background: Naturally occurring radioactivity is a root cause of human exposure to harmful radiation. The occupational exposure hazard due to natural radionuclides occurring in drilling wastes is especially important in this regard. In this study the concentration of radionuclides namely 232Th, 226Ra and 40K were assessed in soil samples that were taken from various oil drilling areas. Methodology: 10 samples were collected and sealed for two months to ensure the secular equilibrium between 226Ra and 232Th, and their respective radioactive progenies. The concentration of radionuclides in samples was measured by gamma spectroscopy. Descriptive and analytical statistics were used in order to analyze the data. Results: the results showed the average absorbed dose rates (D), annual effective dose (AED), Radium equivalent activity (Raeq) and various hazard indexes(Hex, Hin and Iγ ) for samples were 38.22 nGy/h, 0.046 mSv/y, 81.032 Bq/Kg, 0.21, 0.31 and 0.59, respectively. Conclusions: The mean activity concentrations were lower than the world mean values, according to the radiation protection criteria that identified by UNSCEAR.