Abstract
Petroleum oil is the major natural resource for Libya upon which the Libyan economy depends over the years and still for income earnings. Consequently, every year the Naturally Occurring Radioactive Materials (NORM) waste production volume is increasing, which must be monitored and managed properly by regulatory bodies to prevent illegal disposal of contaminated materials and random industrial discharges into water bodies. This study is aimed to determine the activity concentrations of naturally occurring and technically enhanced radioactive materials and to assess the radiation levels in sixteen different soil samples collected from a pit with high radiation area around different oil fields in the Sirte basin in middle of Libya. Representative soil samples have been collected and analyzed using a gamma spectroscopy system based on High Purity Germanium (HPGe) detector housed in the Nuclear Radiation Laboratory at the Department of Nuclear Engineering, University of Tripoli, Libya, in order to establish activity concentrations associated with the 235U, 238U, and 232Th natural decay chains and 40K. The activity concentrations were high for all samples and significantly higher than the worldwide average as reported by the UNSCEAR (2000). The weighted mean values of the activity concentrations of 238U, 232Th were in the range of 3000 Bq/kg; while it was 620.29 Bq/kg for 40K. The annual effective dose equivalent in mSv/y ranged between 0.606 and 23.03 mSv/y; while the world average annual effective dose equivalent (AEDE) from outdoor or indoor terrestrial gamma radiation was reported as 0.460 mSv/y. The achieved results evidenced the necessity for monitoring the oil waste for radionuclide content to decide about the possibility of minimizing the environmental impact of NORM and their final disposal. NORM waste disposal management according to the national and international agreements and conventions are mandatory in Libya for a clean environment.