Radiological assessment of gamma and radon dose rates at former uranium mining tunnels in Egypt

Radiological assessment was carried out at the mining tunnels (El Missikat and EL Aradiya tunnels) in Egypt due to exposure to radon (²²²Rn), thoron (²²⁰Rn) and gamma radiation. ²²²Rn/²²⁰Rn measurements were carried out with two techniques; instantaneous (active) and discriminative (passive) radon and thoron solid-state nuclear track detectors were used for longer representative measurements. The detectors were exposed for a long time inside the tunnels. The results showed that radon and thoron in general, are very high due to non-ventilation drafts inside the tunnels and gamma radiation was low. The total annual effective doses exceeded the permissible limit 20 mSv year⁻¹. According to IAEA recommendations, the two tunnels are regulated and controlled areas. A radiation hazard could be associated with exceptional situations, such as elevated exposures to ionizing radiation at tunnels, so work within these tunnels must be prevented until the application of IAEA regulation for radiation protection standards. The exposure for radon and thoron gases for a long time can damage the body cells and cause cancer.