Measurements of natural radionuclide levels and hazards in the Lega Dembi gold mine, Oromia, Ethiopia.

This study aimed to evaluate natural radioactivity levels and hazards of radionuclides ²³²Th, ²²⁶Ra and ⁴⁰K in soil samples taken from 15 locations in the Lega Dembi gold mining, Oromia, Ethiopia, using gamma-ray spectroscopy coupled with an HPGe detector. It was observed that the respective mean specific activities for ²²⁶Ra, ²³²Th and ⁴⁰K determined in the mining site were 23.87 ± 0.7, 52.5 ± 1.8 and 391.62 ± 11.35 Bq/kg, and 8.89 ± 0.4, 13.83 ± 0.6 and 423.68 ± 9.5 Bq/kg in the living areas. The specific activity of ²³²Th was above the permissive limit in the mining site, while for ²²⁶Ra and ⁴⁰K were within the limit. The specific activity of ⁴⁰K in the living area was observed to be above the permissive limit. The calculated value of radiation hazards parameters; radium equivalent activity (Ra_eq), internal and external hazards indices (H_in) and (H_ex), the mean annual effective dose (AED), and gamma representative indices (I_γ) were within permissively limit. The mean absorbed dose rate in the mining site was above the recommended safety limit. The total annual gonadal dose equivalent value was found to be 494.8 ± 8.7 µSv/a in the mining site. This value was also above the permissively.