NATURAL RADIOACTIVE ELEMENTS AND HEAVY-METALS IN COAL, FLY-ASH AND BOTTOM ASH FROM A THERMAL POWER-PLANT

composition of coal used as fuel at a thermal power plant and those oi the fly and bottom;ashes it produces were determined. Radioactive ele ments were analysed for by alpha and gamma spectrometry, while sulphur , carbon and nitrogen were determined by burning. Heavy metals were qu antified by X-ray fluorescence spectrometry and inductively coupled pl asma atomic emission spectroscopy (ICPAES). The low sulphur content of the coal (0.68%) gives rise to fly ash containing only 0.21% of this element. The radiochemical analyses performed by alpha spectrometry re vealed that most of the uranium remains in the solid residue resulting from disaggregation of the sample with Na2CO3 in the separation proce ss. Also, the gamma spectrometric results show that the elements from the 4n and 4n + 2 series and K-40 concentrate in fly ash, the mean par ticle size of which is the smallest of all the residues assayed.