Assessment of natural radioactivity and radon exhalation rate from fly ash of Kota thermal power station, Kota, Rajasthan

In India, coal is an important source of power generation. Combustion of coal results in generation of huge amount of ash, which is a major environmental problem as it contains natural radionuclides and few toxic heavy elements. The natural radionuclide in coals release to the atmosphere, gives rise to one of the components of technological natural radiation. In this study our main concern is the assessment of the radiation exposure from coal burning, critically dependent on the concentration of radioactive elements in coal and in the fly ash that remains after combustion. Radioactivity of fly ash samples which have been determined by using the high purity germanium detector. The concentration of 226Ra, 232Th and 40K were found to vary from 107± 4.7 to 171.5+9.8 BqKg-1, 124.0.+2.0 to 176.9+4.5 BqKg-1 and 316.1+4.1 to 450+5.8 BqKg-1 respectively. Whereas radium equivalent activity, absorbed, indoor and outdoor effective doses were found to vary from 321.2 to 459.2 Bq Kg1, 143.3 to 204.9 D nGyh1, 0.70 to 1.0 mSv and 0.18 to 0.25 mSv respectively. Radon mass and surface exhalation rates were also analyzed, which were found to vary from 98.5+7.0 to 297+15.9m Bqm-3h-1 and 3.8+0.3 to 11.4+0.6 BqKg-1h-1, radon effective dose and fatal lung cancer risk were also found which varied from 0.47 to 1.35 mSv y-1 and 8.0 x 10-4 to 1.0 x10-3 respectively. (author)