Fly ash fallout gamma radiation distribution around a coal based thermal power plant and its radiological health risk

The study assessed outdoor gamma radiation levels associated with fly ash dispersion from a 2820 MW coal-fired super thermal power plant located in Jhajjar district, Haryana, India. Gamma dose rates (GDR) were measured at 46 locations within a 20 km radius of the plant and at six reference locations beyond 20 km, during summer and winter seasons. The spatial distribution of radiation was heterogeneous, with two distinct hotspots identified along the east-west axis, attributable to increased fly ash deposition driven by prevailing local wind conditions. Measured GDR ranged from 92 to 206 nSv/h, with a mean value of 140.86 ± 32 nSv/h, which is notably higher than the regional background mean of 93.8 ± 20 nSv/h recorded beyond 20 km. The estimated annual effective dose (AED) varied between 0.112 and 0.257 mSv/y with a mean value of 0.171 mSv/y, remaining below the internationally recommended public dose limit. Excess lifetime cancer risk (ELCR) within the hotspot zones ranged from 4.20 × 10^-4 to 9.64 × 10^-4 with a mean value of 6.45 × 10^-4, compared with a mean of 4.16 × 10^-4 at locations beyond 20 km. These values correspond to approximately 645 and 412 excess cancer cases per million individuals, respectively. The findings highlighted the potential long-term radiological health risks in the vicinity of coal-based thermal power plants. Furthermore, the study established radiological baseline data that  would be essential for ongoing and future environmental monitoring programs.