The release of natural radioactive materials with the emission of fly ash as a result of coal burning in power generation plants is considered amongst the sources that elevate the technologically environmental radioactivity level. This research mainly concerns the assessment of various radiological parameters including excess lifetime cancer risk due to natural radioactive contents associated with fly ash emitted to the surrounding environment from the stack of 1320 Mw Sahiwal coal-fuelled power generation plant (CFPP). For this purpose, fifty-four soil samples were collected in a radius of 4 Km from CFPP and a highly background radiation-shielded HPGe system is used to measure radioactivity in the collected samples. The activity concentrations of radium-226, potassium-40, and thorium-232 in collected samples was found to be in the range of 20 to 138, 43 to 860, and 27 to 127 Bq/kg with average values of 66, 409, and 67 Bq/kg respectively. Activity concentrations of radium-226 and thorium-232 were observed significantly higher than UNSCEAR reported typical global average values. A significant decrease in the level of the aforementioned radionuclides in the collected soil samples was observed with increasing distance from the power plant, which is a clear indication for the elevation of radioactivity concentrations in the surrounding environment as a result of the operation of the CFPP. To assess the radiation dose delivered to the occupational workers and inhabitants living next to Sahiwal CFPP, absorbed γ-dose rate (Dγ), outdoor annual effective dose rate (EOutdoor), and excess lifetime cancer risk (ELCR) were estimated and these were found higher than the UNSCEAR recommended values of 59 nGy/h, 0.07 mSv/y, and 2.9 × 10-4 respectively. The outcome of this first systematic study is the assessment of potential radiological health risk to the occupational workers as well as the inhabitants living in the proximity of this CFPP.
Keywords: Coal-fuelled power plant; HPGe detector; Radiation risk; Sahiwal; Soil.