High airborne radioactivity levels due to radon in some non-uranium mines in India

Ten non-uranium mines from various regions of India have been surveyed for airborne radioactivity due to radon daughter products. The average air concentrations of RaA, RaB and RaC in the main ventilation return airways and in some selected areas in different working levels underground were assessed. The average equilibrium equivalent radon values and the RaC to RaB ratios were calculated. In one of these mines activity levels of the order of 500 to 1200 mWl were observed in different working areas. In all other mines the levels observed varied from a few mWL to about 100 mWL. The method of air sampling and analysis is briefly described. (author)