Assessment of Naturally Occurring Radioactive Materials (NORMs) in soils from the Kucova oilfield, Albania

摘要

Oil and gas exploration activities belong to the industrial sectors involving the production of NORMs because of the enhancement in radium isotopes concentrations recorded in industrial residues. According to the European recommendations of the new Basic Safety Standards for radioprotection, each member state shall identify NORM industries and estimate their environmental and human impact. In this framework, the concentrations of uranium and thorium decay series, as well as of ~(40)K were measured in soil, sludge and oil sand samples collected in the Kucova oilfield (Albania) by using a high resolution gamma-ray spectrometer (HPGe). The levels of radioactivity in soil samples were found to be comparable with the world mean activity concentrations. Oil sand samples showed the highest ~(40)K and ~(226)Ra activity concentrations, indicating the presence of shale traps, which are generally rich in natural radionuclides. No strong evidences on disequilibrium were observed from the ratio of ~(228)Th and ~(228)Ra activity concentrations. The concentration of radionuclides in produced water and crude oil were found to be minimum detectable activities. From the radiological point of view, the excess of annual effective dose rate from industrial residues was estimated to be much lower than the recommended limits for population and workers.