Re-Assessment of Radiological Hazards of Naturally Occurring Radioactive Materials (Norm) from the Jubilee Oilfields of Ghana

Abstract

This study re-assesses the radiological hazards of Naturally Occurring Radioactive Materials (NORM) on workers and the general public due to continuous exploration and production of crude oil and waste generated from the Jubilee Oilfields of Ghana. The specific activities of 234U, 238U, 230Th, 232Th, 226Ra, 210Pb, 234Th, 228Ra, 224Ra and 40K in crude oil and NORM waste samples have been estimated using Sodium Iodide detector and alpha spectrometry after radiochemical separation. A trend analysis of an increase in the activity concentrations of radionuclides has also been established between the previous study and this study using a statistical test of association (paired t-test) at 95% confidence interval. An annual effective dose of 1.32 mSv obtained for occupationally exposed workers in this study was below the International Commission on Radiological Protection (ICRP) recommended dose limit of 20 mSv per year (averaged over 5 years and not exceeding 50 mSv per year in any single year). From the study, radium concentrations are of radiological importance for sludge and produced water due to the high levels of activity concentrations recorded. There is also tendency for possible increase levels of activity concentration of these radionuclides with time as exploration and production continues with more wells being drilled. As a result it is recommended that a national guideline for monitoring of NORM is established to ensure regulatory monitoring of these facilities in Ghana.