Radiology dose assessment of naturally occurring radioactive materials at petroleum gas separation stations in Rumaila, Iraq

Abstract

Accurate evaluation of radiological dose from naturally occurring radioactive materials (NORMs) generated by petroleum gas separation stations remains challenging. Protection of human health from unwanted radiation exposure, and minimization of environmental pollution from these NORMs are the main motivations of this work. These could be achieved by evaluating the activity concentrations (ACs) of various identified radioactive elements in the soil, sludge, and wastewater samples collected from seven petroleum gas separation stations located in Northern Al-Rumaila of Iraq. In this study, high purity germanium (HPGe) detector was used to measure the ACs of 232Th, 226Ra, and 40K radioactive isotopes present in the soil, sludge, and wastewater samples. Radiometric analyses were performed on wastewater samples, while 238U activities were recorded using fluorimetry technique. The gamma absorbed dose rates in air were measured using survey meters. Gross alpha/beta measurements were also conducted for the collected wastewater samples. Radiation hazard parameters were examined at these gas separation stations to estimate the potential radiological health risk in the sediments/sludge/wastewater samples. The findings showed that the mean value of ACs of 232Th, 226Ra and 40K in soil samples measured were 106.05 ± 4.34 Bqkg-1, 209.91 ± 8.43 Bqkg-1 and 302.20 ± 13.07 Bqkg-1, respectively. The ACs for 226Ra, 232Th and 40K in the sludge samples were considerably greater than IAEA guidelines. Furthermore, the ACs of 232Th and 226Ra were discerned to be higher, and 40K was lower than the world average. Results of the radiometric analysis of water samples revealed a wide variation in the detected activities of 228Ac, 226Ra, 40K and 238U from below the detection limit until 11.17, 22.63, 19, and 0.92- 6.46 BqL-1 respectively. Simulation was performed using RESRAD software to estimate the yearly dose where the yearly dose for various NORMs present in the samples were found to be maximum (64.67 μSv.y-1) at DS4 station. Results of this study clearly demonstrated that radioactivity levels in the wastewater samples exceeded the limits set for by the World Health Organization for drinking water. If no remedial steps are implemented, then there is a potential for long term risks to the health of the community and those who rely on recycled water in this Iraqi region.