Determination of surface radiation dose-rate in the environment of Kelantan State, Malaysia

Abstract

Measurements of environmental surface radiation dose rate in Kelantan state, Malaysia was carried out using a portable hand held radiation survey meter and Global Positioning System (GPS). The surface radiation dose rates ranged from 44 to 500 nGy h-1. The measurements were done based on geology and soil types of the area. The mean radiation dose rate was found to be 209 ± 8 nGy h-1. Few areas of relatively enhanced activity were located in Pasir Mas, Tanah Merah and Jeli districts which have external gamma dose rates between 300 to 500 nGy h_1. An Isodose map of the state was produced using ArcGIS10 software version 10.1. To evaluate the radiological hazard due to terrestrial gamma dose, the annual effective dose equivalent (AEDE), the mean population weighted dose rate and cancer risk factor were calculated and found to be relative excess lifetime cancer risks were 1.280 mSv y-1, 18 mSv and 1.04×10-3 respectively.