Terrestrial Gamma Radiation Dose Rate of West Sarawak

Science Faculty, Universiti Teknologi Malaysia, Skudai, 81310. Johor Bahru, Malaysia

Published online: 23 October 2017

Abstract

A study of terrestrial gamma radiation (TGR) dose rate was conducted in west of Sarawak, covering Kuching, Samarahan, Serian, Sri Aman, and Betong divisions to construct a baseline TGR dose rate level data of the areas. The total area covered was 20,259.2 km², where in-situ measurements of TGR dose rate were taken using NaI(Tl) scintillation detector Ludlum 19 micro R meter NaI(Tl) approximately 1 meter above ground level. Twenty-nine soil samples were taken across the 5 divisions covering 26 pairings of 9 geological formations and 7 soil types. A hyperpure Germanium detector was then used to find the samples’ ²³⁸U, ²³²Th, and ⁴⁰K radionuclides concentrations producing a correction factor C_f = 0.544. A total of239 measured data were corrected with Cf resulting in a mean Dm of 47 ± 1 nGy h^-1, with a range between 5 nGy h^-1 - 103 nGy h^-1. A multiple regression analysis was conducted between geological means and soil types means against the corrected TGR dose rate Dm, generating D_g,s= 0.847Dg+ 0.637Ds- 22.313 prediction model with a normalized Beta equation of D_g,s= 0.605D_g+ 0.395D_s. The model has an 84.6% acceptance of Whitney- Mann test null hypothesis when tested against the corrected TGR dose rates.