Technologically enhanced natural radionuclides in hard coal fly ash and associated radiological hazard assessment using RESRAD modeling.

Coal fly ash (CFA) generated by thermal power plants is classified as technologically enhanced naturally occurring radioactive material (TENORM) that poses potential hazards to human health and the environment. This study assesses the radiological hazards associated with CFAs from the Çatalağzı thermal power plant, Türkiye's pioneering domestic hard-coal-fired thermal power plant that produces approximately 750,000 tons of silico-aluminous CFA annually. The mean activity concentrations of 228Ra, 226Ra, and 40K measured in CFA samples by gamma-ray spectrometry with a high purity germanium detector were found as 117 ± 7, 118 ± 9, and 1106 ± 98 Bq kg-1, respectively. The radiological hazard assessment, based on the calculated alpha/gamma indices, annual effective doses, and lifetime cancer risks, indicated that the examined CFAs are radiologically safe for utilization in cement and concrete production. Furthermore, site-specific occupational exposure scenarios for power plant workers were simulated using the RESRAD-ONSITE computer code. The RESRAD simulation revealed that the total effective dose rate in an open CFA landfill reaches its maximum at 18 years (0.14 mSv y-1), while the lifetime excess cancer risk peaks at 9 years (2.78 × 10-4). These findings provide a comprehensive framework for the safe environmental management and industrial reuse of hard coal TENORM wastes.