Natural Gamma Radiation in Rocks from Kerri-Kerri Formation, Northeastern Nigeria

In a study on uranium favourability in Nigeria, it was suggested that the Kerri-Kerd Formation located in the Upper Benue Trough, Northeastern Nigeria is a potential host of uranium mineralization, hence the need to assess the level of natural gamma radiation from the rocks of the area. Laboratory gamma-ray spectrometric analysis was carried out with a HPGe detector by (EG & G Ortec Inc.) at the Center for Energy Research and Training, Ahmadu Bello University, Zaria. Thirty six (36) rock samples were collected from the study area from which nine (9) composite samples were formed for the laboratory gamma-ray analysis. The mean concentrations of the radionuclides (238)u, Th-232 and K-40 were 26.9988 Bq/kg, 61.9131 Bq/kg and 91.7042 Bq/kg respectively. The mean absorbed dose rate was 15.646 nGyh(-1) which is lower than the world average value of 51.5 nGyh(-1). The average internal and external hazard indices were found to be 0.404 and 0.331 respectively which are lower than the acceptable limits of <1. The mean radium equivalent (Ra-eq) value was 122.60 Bq kg(-1) which is well within and less the permissible limit of 370 Bq kg(-1). Since the radiological hazard parameters are all lower than the permissible limits, the study area can be considered as safe due to natural gamma radiation and the rocks of the area can be used safely for building and construction purposes. (C) 2017 Elsevier Ltd. All rights reserved.