Determination of Radiological Hazard Associated with the use of Imayan River Sediment as Building Material

Abstract

The radioactivity concentrations of ⁴⁰K, ²³⁸U and ²³²Th in sediment samples of Imayan river at Odogbolu local government area, Ogun State in Nigeria were determined by gamma spectrometry using NaI (TI) detector coupled with a pre-amplifier base to a multiple channel analyzer (MCA), these were then used to determine the radiological indicators; radium equivalent activity, internal and external hazard indices, and absorbed dose rate which translated to the annual effective dose rate. 10 sediment samples were collected from the river. The highest radioactivity concentrations of ⁴⁰K, ²³⁸U and ²³²Th obtained from the sediment samples were 110.34 ± 10.68Bqkg^-1, 9.02 ± 3.16Bqkg^-1 and 11.56 ± 4.23Bqkg^-1 respectively. The mean external hazard index (Hex) and mean internal hazard index (Hin) for all the sediment samples were calculated to be 0.066 Bqkg- 1 and 0.081Bqkg^-1 respectively, while the mean radium equivalent activity was obtained to be 24.62Bqkg^-1. Absorbed dose rate mean value was calculated to be 17.41nGyhr^-1 with mean annual effective dose rate of 0.022mSvyr^-1The values of the radiological indicators were found to be within the limits recommended for safety, indicating that the use of the sediment of the river as building material does not have radiological health hazards to the occupants of the buildings. ©JASEM

KEYWORDS: Concentration, radionuclide, radiological indicators, absorbed dose rate