Spatial Variation of Radon Concentration Around a Coal-Fired Thermal Power Plant

Radon is a major contributor to natural radiation exposure, and its presence in residential areas near industrial facilities is a key concern in environmental radiation protection. This study assessed radon levels at different distances in the area surrounding the Simhadri National Thermal Power Corporation (NTPC) coal-fired plant in Paravada, Visakhapatnam, Andhra Pradesh, India. Radon levels were monitored using the Smart RnDuo system, which provides precise activity measurements along with relevant environmental parameters influencing radon transport. Measurements were taken at 120 locations distributed across nearby villages and categorised into high, medium, and low-proximity zones to examine spatial variation around the thermal power plant. The results showed measurable differences in radon concentration across the study region, indicating that distance from the plant affects radon dispersion and accumulation. Although all values remained within internationally accepted limits, the distribution pattern revealed that specific low-proximity locations recorded comparatively elevated concentrations. This suggests that the effects of local geological formations, soil permeability, and natural ventilation characteristics are more significant than those of industrial emissions alone. Variations in soil composition, ground moisture, and underlying rock structures likely contributed to the observed differences, highlighting the complexity of radon behaviour in heterogeneous terrains. The study further demonstrates the suitability of the Smart RnDuo system for field-level radon monitoring, offering stable performance and reliable data even under varying environmental conditions. The findings provide baseline information on outdoor radon levels around a major coal-fired installation and emphasise the importance of continued monitoring to better understand long-term environmental trends. By identifying distance-related variations in radon distribution, the study provides valuable insights for radiation protection planning in regions near large-scale industrial facilities.