Evaluation of naturally occurring radioactive materials in oilfields of south east of Libya

An investigation was carried out to find out the concentration of NORMs in evaporation ponds sludge in south eastern oilfield of Libya. Activity concentrations of 226Ra, 232Th and 40K in soil generated during oil production operations were determined using a gamma spectroscopy system based on high purity germanium (HPGe) detector. Concentrations ranged from 83 to 1000 Bq kg−1 for 226Ra, 59 to 315 Bq kg−1 for 232Th and 109 to 304 Bq kg−1 for 40K. To evaluate the radiological effects, radium equivalent activity and external hazard are calculated. The magnitude of these results demonstrates the need of these ponds for a special treatment on site to reduce the exposure to a value below 100 μSv/y, by mixing the pond after drying the lagoon with clean soil to reduce the dose rate and minimise the environmental impact of NORM.