Radiometric Survey of Granitic Quarry Site of Ebony State, Nigeria

Abstract

Radiometric survey of the granitic quarry site at Ishiagu and its environment was done using two radiation monitors and geographical positioning system (GPS) for GIS mapping. In-situ measurement of exposure rate was carried out following the international standard organizational standard between May 2018 and June 2019. The measured average exposure rates ranged from 0.010± 0.002 to 0.038 ± 0.003 mRh-1 with mean value of 0.026 ±0.005 mRh-1. The estimated outdoor absorbed dose rate ranged from 87.0 to 330.6 nGyh-1 with mean value of 228.38 nGyh-1. The equivalent dose rate ranges from 0.84 to 3.20 mSvy-1 with mean value of 2.21 mSvy-1. The mean annual effective dose equivalent (AEDE) calculated was 0.28 mSvy-1 while the mean excess lifetime cancer risk (ELCR) was 0.98 x 10-3. The estimated annual effective dose to different organs showed that the testes have the highest annual effective  dose of 0.191 mSvy-1 followed by ovaries and kidney of 0.135 and 0.139 mSvy-1 respectively while the liver has the lowest annual effective  dose of 0.103 mSvy-1. The radiation contour map of the area showed the distribution of radiation of high and low areas. The result showed that the radiation exposure rate and its associated radiological risk parameters exceeded the safe limits prescribed by ICRP and also the values reported in literatures. However, these values may not constitute acute health risk but long term exposure of residents and workers may be detrimental to their health. Therefore adequate monitoring of this quarry site is necessary to checkmate the exposure rate and provide some protective measures for quarry workers.