EVALUATION OF RADIATION DOSES AND HAZARD INDICES IN CRUSHED ROCKS FROM SOME QUARRIES IN IBADAN SOUTHWESTERN NIGERIA

The radiological assessment of rock samples from four quarry sites in Ibadan have been carried out. The mean activity concentrations of 40K, 226Ra and 232Th were 377.0 ± 37.9, 17.7 ± 3.6 and 4.98 ± 2.1 Bq kg-1, respectively, for Ratcon Quarry (RQ); 408.0 ± 28.7, 16.6 ± 1.6 and 10.6 ± 2.3 Bq kg-1, respectively, for Dekit Quarry; 388.0 ± 26.6, 15.7 ± 1.9 and 9.85 ± 3.9 Bq kg-1, respectively, for Hajaig Quarry; and 388.084 ± 55.9, 16.2 ± 3.9 and 12.1 ± 3.8 Bq kg-1, respectively, for NSCE Quarry (NQ). The highest mean outdoor effective dose of 0.038 ± 0.005 mSv y-1 and the minimum of 0.033 ± 0.004 mSv y-1 were obtained at NQ and RQ, respectively. The radiological hazard indices recorded in each site were <1.0. The results show lower radioactivity levels than the world average values; therefore, no serious radiological health effect is expected when the crushed rocks from the quarries are used for buildings construction.