Mapping of Terrestrial Gamma Radiation Isodose in Sabah State, Malaysia

Abstract

Abstract Research has been conducted to achieved data of background level of terrestrial gamma radiation for Sabah State. This research is conducted with a sampling technique where sampling location is selected according to soil type, geology, and minerals. Results were analyzed as geospatial to map the terrestrial gamma radiation isodose. The results of measurement at 1,054 locations showed that the min dose rate of terrestrial gamma radiation for Sabah State is 73 ± 1 nGyhr-1. This value is nearly the min global dose rate estimated by UNSCEAR which is 59 nGyhr-1. However, it is lower when compared to min dose rate measured in Peninsular Malaysia which is 190 ± 1 nGyhr-1. The highest dose rate measured is 190 nGyhr-1 in Lobong-lobong village near to Mount Kinabalu (igneous zone) and the lowest dose rate was 5 nGyhr-1 measured at Pulau Mabul. The existence of few location with high and low terrestrial gamma radiation anomaly is because of the difference geology background and soil types from lithology system in Sabah State. Isolated cases of high terrestrial gamma radiation dose rate is because of high natural radioactivity soil coming from plutonic and volcanic that existed as a separated debris. Measured gamma radiation dose level in Sabah is low because of domination by rock lithology with low radioactivity from metamorphic and sedimentation types. This low dose is classified as the normal dose level for ionized radiation coming from environment. Exposure by public from terrestrial gamma radiation in Sabah State does not producing dangers to public's health. The data from this research is important as a base data for terrestrial gamma radiation level. At present, this data is never established at federal level although it is important as a reference for government in conducting studies e.g., laws enforcement on the usage of radioactive materials or to address the Licensing Act for nuclear industry. On top of that, the results from this research such as isodose map could convince the public that the Government of Malaysia had information and scientific data towards radiation safety especially nuclear waste issues.