Measurement of natural radionuclides and dose assessment of granites from Ondo State, Nigeria

The activity concentrations of Ra-226, Th-232 and K-40 in fifty granite samples collected from five different quarry industries in Ondo State, Nigeria, were determined using gamma-ray spectrometry. The mean activity concentrations for each industry ranged from 16.7(6.4) to 85.4(23.0), 62.4(10.1) to 113.6(7.6), and 1315(136) to 1551(84) Bq.kg(-1) for Ra-226, Th-232 and K-40 respectively. The values in parenthesis are the standard deviations. When compared with results from some parts of the world, the Ra-226 and Th-232 contents were lower, whereas the K-40 content was similar. Using different approaches to estimate the potential radiological hazard of the samples, the results obtained were below the recommended maximum limits. This shows that the radiological hazards associated with the use of the granites examined in this study as building material are within the acceptable limit.