Radon-222 and naturally occurring radioactive materials (NORMs) radioactivity concentrations and radiological impact assessment of two sediment deposit areas in Cameron Highlands, Pahang

The migration and accumulation of sediments into water bodies would pose adverse problems, in particular if the water bodies (reservoirs) used to provide potential energy for hydroelectric power station. The sediments would render huge reduction to the water retention capacity of the reservoirs, thus reducing the energy generation efficiency. However, dredging works of river sediments from Sungai Jasik (Ringlet Dam) and Sungai Sekam (Jor Dam) potentially cause unresolved issues concerning pollution, toxicology and leaching of contaminants from dredged material. Indirectly, affecting workers and local peoples’ health if they are continuously expose to the NORMs carried in the sediments. Thus, monitoring of radiologically impact assessment are required to ensure the NORMs are not risking human health. This work was carried out to measure the radon and radioactivity level of three radionuclides (⁴⁰K, ²³²Th and ²³⁸U) in dredged sediment from two TNB’s sediment deposit areas in Cameron Highlands; Sungai Jasik and Jor areas. The concentrations of radon- 222 (²²²Rn) in 11 dredged sediment samples were measured using CR-39 method. Meanwhile, radioactivity concentrations of potassium-40 (⁴⁰K), thorium-232 (²³²Th) and uranium-228 (²²⁸U) were measured using energy dispersive X-ray fluorescence (EDXRF) spectrometer in 32 dredged sediments samples collected from respective sites of Sungai Jasik and Jor sediment deposit areas. The concentrations of ²²²Rn in soil are in the range of 4.5 – 219.6 Bq/m³ and it is lower than the action level set by ICRP, 1993. The radioactivity concentrations of three NORMs are in the range of 68 -1159, 28 – 135 and 8 -130 Bq/kg for ⁴⁰K, ²³²Th and ²²⁸U, respectively. Statistical analysis of the radionuclides concentration showing there is no significant difference between the two sediment deposit areas. The values of radionuclides concentrations however translate to the determination of the radiological impact assessment values including Radium Equivalent Activity (Ra_eq), Absorbed Dose Rate, Annual Effective Dose (AED) and External Hazard Index (H_ex). All values obtained were observed to be lower than the international limit set by UNSCEAR, 2000. Thus, the radionuclides activity in the study areas are likely pose no radiological risk to human and surrounding environment.