Radiological hazard assessments of natural radionuclides in surface soil in Chau Binh, Vietnam

An assessment of primordial concentrations in soil samples from Chau Binh, Nghe province, Vietnam, was conducted to evaluate potential radiological hazards to local inhabitants. The average activity concentration of the radionuclides determined using HPGe γ-ray spectrometry, were found to be (96.8 kg −1 ) for 238 U, (249.7 kg −1 ) for 232 Th, and (473.5 kg −1 ) for 40 K, being higher than the world average concentration values. The risk indices computed, subsequently, indicate the absorbed dose (42.6 – 362.5 nGyh - 1 ) and annual effective dose equivalents (1.3 mSv) received by individuals to be higher than the permissible limits recommended by UNSCEAR. Such high radiation levels in Chau Binh attributes to the geological characteristics of the soil which is deposited with rich placers of monazite mineral. The composition including orthophosphate, Silimanite, Garnet, Biotite-amphibolite quarsite and marble lenses further adds to the elevated levels of radioactivity in this region. In addition to this, higher concentration of 232 Th than 238 U, indicates the environment to be oxidizing in nature. • A.C of 238 U, 232 Th and 40 K- were beyond the permissible limit. • High radiation levels in soil is due to the presence of monazite. • Significant radiological risks to the inhabitants due to higher AEDE, D R and ELCR.