Measurement of Natural Occurring Radio nuclides (NORMs) in Soil using Gamma- ray Spectrometry

Abstract

The aim of this work is focused on preparation and using gamma- ray spectrometry to investigate and demonstrate a method to determine and evaluate natural radio nuclides which are uranium, thorium and potassium and their activity concentrations, radium equivalent activity , absorbed dose rates in air at one meter above the ground surface and the annual external and internal effective dose rates . The spectrometer consists of NaI (Tl ) detector coupled with preamplifier and ADC of 4096 Chanel memory , CASSY type. The suitable gain was determined. The efficiency , energy calibration and resolution had been measured by using some standard source .. In order to evaluate the radiological impact for the population , four soil samples have been Collected from different localities in middle area of Najaf province , and measured in which 238U ,232Th and 40K were noted. The value of activity concentration ranged from 4.84±0.52 to 17.52±0.94, 5.92±0.31 to 7.07±0.344 and 103.39±2.52 to 185.48±2.09 (Bq kg-1) for 238U, 232Th and 40K respectively . The calculated values of radium equivalent activity (Raeq ) ranged from 25.25 to 33.94 (Bq kg-1) whereas absorbed doses varied from 12.35 to 16.09 (Bq kg-1) . Annual effective Doses were found to be in the range (0.061) to (0.079) and (0.015) to (0.020) (mSv) for indoor and Outdoor respectively . The comparison between our results and standard levels recommended by the IAEA and UNSCEAR show low radiation level .