Assessment of Radiological Hazard Indices Due to Natural Radionuclides in the Soil of Irele Local Government Area, Ondo State Nigeria

This study measured the naturally occurring radionuclides (U-238, Th-232, and K-40) in sixteen selected soils samples of Irele local government area in Ondo state, southwestern Nigeria using a thallium-doped sodium iodide gamma-ray spectrometry detector. The values of concentration of natural radionuclides in the soils ranged from 16.18-32.16 with a mean value of 27.58 Bq.kg(-1), 10.38-24.15 with a mean value of 16.92 Bq.kg(-1), and 321.13-528.18 with a mean value of 423.05 Bq.kg(-1) for U-238, Th-232, and K-40, respectively. The values of the assessed radiological parameters (absorbed gamma dose rate in air, annual effective dose rate, radium equivalent activity, and the external hazard index) are found to range from 30.81-47.11 with a mean value of 40.60 nGy.h(-1), 0.19-0.29 with a mean value of 0.25 mSv.y(-1), 62.53-98.25 with a mean value of 84.35 Bq.kg(-1) and 0.17-0.27 with a mean value of 0.23, respectively. The obtained values are lower than the recommended world average of 33, 45, and 450 Bq.kg(-1) for U-238, Th-232, and K-40 published by the United Nations Scientific Committee on the Effects of Atomic Radiation and the National Council on Radiation Protection and Measurement.