Radiological Assessment of Radionuclide Contents in Soil Waste Streams from an Oil Production Well of a Petroleum Development Company in Warri, Niger Delta, Nigeria

Abstract

Activity concentrations of naturally occurring radionuclides in the soil waste stream in the sedimentation tanks of an oil and gas production well site of a major Petroleum Development Company in Nigeria have been measured using gamma-ray spectroscopy. The gamma-ray peaks observed with reliable regularity in all the samples analysed belong to naturally occurring radionuclides. Radioactive elements such as 137 Cs were not detected in the samples indicating no contamination by radioactive sources in the operations at the site. The concentrations of the radionuclides in the samples ranged from below detection level to 248.2 ± 14.0, 29.9 ± 8.8 to 122.3 ± 13.6 and 12.4 ± 1.2 to 28.6 ± 1.9 Bq · kg-1 for 40K, 226Ra and 232Th respectively. The absorbed dose rates ranged from 25.3 to 73.3 nGy · h-1 with mean 52.6 ± 17.9 nGy · h-1, while the annual outdoor effective dose varied from 31.1 to 89.9 µSv with mean 64.6 ± 21.9 µSv. The cumulative cancer mortality and morbidity risk due to the radionuclides were 8.64 × 10-5 and 1.27 × 10-4, respectively. The results of measurements showed low values of the parameters determined, it suffices to say that the soil waste streams do not create any significant health concern for the workers and the environment and hence they can be used for building and development purposes in the area.