ASSESSMENT OF IONIZING RADIATION EXPOSURE LEVELS IN AGBARA INDUSTRIAL ESTATE,OGUN STATE,NIGERIA.

Abstract

In this research, the ionizing radiation exposure levels at different locations in Agbara Industrial Estate were investigated. A total of 60 soil samples and effluents were taken and in-situ radiation measurement was taken at each point where soil samples were collected using a Geiger Muller Counter (KindenooblueGeiger PG-15) and a Global Positioning system (GPS) was used to determine the location of each point. Activity concentration measurement was done using high purity germanium (HPGe) detector. ArcGIS 10.2 software was used to determine the geospatial distributions of the ambient ionizing radiation. The result revealed that the equivalent dose rate (EDR) ranged from 0.09±0.01 μSv h-1 to 0.35±0.03 μSv h-1with a mean of 0.21±0.02 μSv h-1which is above the standard background radiation of 0.13 μSv h-1 set by the International Commission on Radiological Protection (ICRP). The annual equivalent dose rate (AEDR)ranged from 0.16 mSv y-1 to 0.61 mSv y-1 with a mean of 0.37 mSv y-1 which is lower than 1.0 mSv y-1dose limit recommended by the ICRP. The activity concentrations of 226Ra, 232Th and 40K in the soil and effluent samples were measured. In soils, the average values of the absorbed dose rate (D), annual effective dose equivalent (AEDE), radium equivalent activity (Raeq), annual gonadal dose equivalent (AGED), external hazard index (Hex), internal hazard index (Hin), representative gamma index (Iγ) and excess lifetime cancer risk (ELCR) were 14.77 nGy h-1, 0.02 mSv y-1, 31.28 Bq kg-1, 107.51 mSv y-1, 0.10, 0.08, 0.24, and 0.19 respectively. In effluents, the average values of D, AEDE, Raeq, AGED, Hex, Hin, Iγ and ELCR were 6.34 nGy h-1, 0.01 mSv y-1, 14.66 Bq kg-1, 44.97 mSv y-1, 0.05, 0.04, 0.10 and 0.03 respectively. All the calculated radiation hazard indices are lower than the permissible limits of 1 mSv y-1, 370 Bq kg-1, 300 mSv y-1 for AEDE, Raeq and AGED respectively, and 1 for Hex, Hin, Iγ and ELCR as recommended by ICRP. This indicates that the people living and working within the area are not exposed to high doses of radiation as a result of industrial activities in the Agbara Industrial Estate.