Determination of Natural Radioactivity Concentration and Radiogenic Heat Production in Selected Quarry Sites in Ondo State, Nigeria

Abstract

Gamma-ray spectrometer was used to measure radiation from radio-nuclides inside and outside five different quarry sites in Ondo State (Sutol, Batista, Aslos, Johnson and Stoneworks) in order to determine the pattern of natural radioactivity, radiogenic heat production effect and radiological health risk to the population within the site vicinity. The average activity concentration of238U,232Th and40K inside the quarries are 47.09±7.49, 95.02±14.11 and 1118.68±126.94 Bqkg-1 and outside the quarries are 35.76±7.83, 83.17±11.85 and 959.71±96.43 Bqkg-1 consecutively. The total heat production and heat flow values estimated for all the quarries varied from 0.97 to 5.37μWm-3 and 7.63 to 42.12 mWm-2 respectively. The radiogenic heat production variations with the radionuclide from the quarries were presented as plots. Thorium concentration is highest (43.5 ppm) followed by uranium (10.4 ppm). The mean values of all the hazard indices calculated were lower than the internationally acceptable limits. This implies that, the people working in the quarries, granite end-users and general public living around the quarries area are safe from radiological health risk. Considering radiogenic and thermal modeling point of view, the Johnson quarry has the highest concentration of uranium, total heat production and heat flow values. It is a manifestation of the geological rock types and presence of highly weathered minerals. So, it is of most promising Uranium mineralization and further probe for potential geothermal exploration.