Determination of Radioactivity Concentration in Soil Samples of some Potash Mining areas in Yunusari Local Government Area of Yobe State, Nigeria.

Abstract The concentrations and distribution of natural radionuclides in soils samples of some Potash mining areas in Yunusari local government, Yobe State, Nigeria were investigated. Twelve soil samples were collected from four locations to measure their natural radioactivity concentrations due to natural radionuclides (226Ra, 232Th and 40K) using gamma spectrometry technique consisting of Thallium activated Sodium Iodide (NaI (Tl)) detector. The mean activity concentration values for 226Ra, 232Th and 40K are 108.58 ± 2.56 Bq/kg, 59.16 ± 3.08 Bq/kg and 284.32 ± 1.37 Bq/kg respectively. The mean absorbed dose rate was found to be 97.74±2.98 nGy/h, which is above the safety limit. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the hazard index (external and internal hazard index), the absorbed dose rate and the effective dose rate were been calculated and compared with internationally recommended values. The radium equivalent activity values of all samples are lower than the limit of 370 Bq/kg. Also, the values of the external and internal indices are less than unity, except at locations MOZOGUN 1 and KIRIKAKU 3 which has values greater than or equals to unity for the internal hazard indices that is 1 and 1.08 respectively. The mean annual effective dose rate was 0.119mSv/y and is less than 1mSv/y safety limit recommended for the public by International Commission on Radiological Protection (ICRP).