Assessment of natural radioactivity in coals and coal combustion residues from a coal-based thermoelectric plant in Bangladesh: implications for radiological health hazards

To study the level of radioactivity concentra tions from a coal-based power plant (Barapukuria, Ban gladesh) and to estimate the associated radiological hazards, coal and associated combustion residuals from the power plant were analyzed bygamma-ray spectrom etry with high-purity germanium (HPGe) detector. The results reveal that the mean radioactivity (Bq kg−1)con centrations in feed coal samples are 66.5± 24.2, 41.7± 18.2, 62.5 ± 26.3, and 232.4 ±227.2 for U-238, Ra-226, Th-232, and K-40, respectively, while in coal combus tion residuals (CCRs), they are 206.3±72.4, 140.5± 28.4, 201.7 ± 44.7, and 232.5±43.8, respectively. With the exception of K-40, all the determined natural radio nuclides are considerably higher in the investigated feed coal and associated combustion residues as compared with the world soil and world coal mean activities. On the average, CCRs contains 3.10–3.37 times more nat ural radionuclides than the feed coal, except for K-40. The radioactivity of fly ash and bottom ash is fraction ated, and ratio ranges from 1.40 to 1.57. The mean values of the radiological hazard indices in the coal and their associated residuals are 153.1 and 446.8 Bq kg−1 for radium equivalent activity, 0.41 and 1.21 for the external hazard index, 70and 200.1 nGyh−1 for the absorbed gamma dose rate, 0.09 and 0.25 mSv year−1 for the annual effective dose rate, and 3.0 ×10−4 and 8.6×10−4 Sv−1 for the excess lifetime cancer risk, respectively, most of which exceed the UNSCEAR-recommended respective threshold limits. The outcome of this study suggests a potential radiolog ical threat to the environment as well as to the health of occupational workers and nearby inhabitants from the examined samples