Determination of External and Internal Hazard Indices from Naturally Occurring Radionuclide in Rock, Sediment and Building Samples collected from Sikiti, Southwestern Nigeria.

Abstract

A study of natural radioactivity of Rock, Sediment, and Building samples collected from different areas of Sikiti settlement, in southwestern Nigeria was carried out via gamma-ray spectrometry, using NaI (Tl) detector. The mean Activity concentration of 40K, 226Ra and 232Th in Rock samples was 935.05 ± 702.08 BqKg-1, 3.04 ± 5.44 BqKg-1 and 271.69±301.04 BqKg-1 respectively. Mean Activity concentration of 40K, 226Ra and 232Th in Building samples was 426.95±129.19 BqKg-1, 28.15 ± 16.93 BqKg-1 and 107.30±23.83 BqKg-1 respectively, while Sediments samples had 426.03±137.50 BqKg-1, 28.52±10.03 BqKg-1 and 30.32±15.35 BqKg-1 concentrations respectively. The external and internal hazard indices for rock samples were above permissible limit (i.e. >1). Also the external and internal hazard indices for sediment and building material samples were below permissible limit (i.e. <1). Therefore, rocks, sediments, and building materials found in Sikiti settlement may be used by farmers, miners and residents of the area with a lot of caution, to prevent radiation exposure which may result from long term cumulative effect. Keywords: rock, sediment, clay, building materials, activity concentration, internal hazard index, external hazard index, radiation exposure, sikiti, oyo state