DISTRIBUTION OF NATURAL RADIOACTIVITY IN ROCKS FROM IKOGOSI-EKITI, SOUTHWESTERN NIGERIA AND ITS RADIOLOGICAL IMPLICATIONS.

Abstract

The natural radioactivity in some rock samples in Ikogosi-Ekiti, Southwestern Nigeria, has been measured using a very sensitive gamma spectroscopic system consisting of a 76 mm × 76 mm NaI(Tl) scintillation detector system coupled to a versatile Canberra Series 10 plus multichannel analyzer. The average concentrations of natural radioisotopes 238U, 232Th, and 40K are 57.9 ± 28.1 Bq kg−1, 81.6 ± 23.8 Bq kg−1 and 1203.1 ± 687.2 Bq kg−1, respectively. These average values give rise to a mean absorbed dose rate of 0.128 ± 0.051 μGy h−1 at a height of 1.0 m and an effective dose equivalent of 156.90 μSv y−1. The results indicate no radiological anomaly. The data presented here will serve as a baseline survey for primordial radionuclide concentrations in rocks of the area. ©2000Health Physics Society