Omeje Maxwell

Abstract:

The inadequate access to public water supply in Abuja has forced more than 80 % of the population of about 5 million to drill private borehole. Drillers are not aware of rock radioactivity especially Abuja granitic rocks which varies with depth. The radioactivity of 238U and 232Th decay chains for the lithological rock samples could be at equilibrium considering the age as well as the isotopic mass proportion which is assumed to be equal to its natural isotopic. A new approach of using Neutron Activation Analysis (NAA) is adopted for this study with the aim of minimizing sample size as well as less counting rate to estimate the concentration in rock samples. Subsequently, the epithermal method for the decay chain of 238U was also used for 40K decay chain determination. The result was used to determine the radium equivalent index risk on drillers with a value of 400.63 Bqkg‒1 which is higher than 370 Bqkg‒1recommeded by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) by a factor of 1.08. This value of 400.63 Bqkg‒1 may pose hazard health risk on drillers with external hazard index of 1.1 which is higher than 1 recommended by UNSCEAR. The results of this analysis using NAA have indicated that the exposure level due to naturally occurring radionuclides was lower, but safety rules should be applied for the borehole drillers in Abuja and beyond.