CONCENTRATIONS OF RADIONUCLIDES OF SIZE FRACTIONATED FLY-ASH EMISSIONS FROM A THERMAL POWER-PLANT USING TAIWAN COAL

Coal, fly ash and bottom ash samples were taken from a 300-MWe coal-fired power plant with a daily coal consumption of 2400 tons. A high volume sampler coupled with several mesh testing sieves was used to separate fly ash samples into different size fractions. Determination of the concentrations of K-40, U-238, Ra-226, Pb-210, Po-210, Th-228 and Ra-228 was carried out either by gamma or alpha spectrometry. For elements volatilized during combustion, their radionuclide concentrations decrease with increasing particle size. The enrichment factors for all radionuclides mentioned above were studied. Their values range from 31.0 for Po-210 to 2.2 for Ra-228. Of all radionuclides studied, Po-210 and Pb-210 are the most volatile elements; therefore, an increase in the natural radiation level should first be indicated by an increase in these two nuclides.