Radioactivity of coals and fly ashes

The level and the behavior of the naturally occurring primordial radionuclides U-238, Ra-226, Pb-210, Th-232, Ra-228 and K-40 in coals and fly ashes are described. The activity concentrations of the examined coals and originated from coal mines in Greece ranged from 117 to 435 Bq(.)kg(-1) for U-238, from 44 to 255 Bq(.)kg(-1) for Ra-226, from 59 to 205 Bq(.)kg(-1) for Pb-210, from 9 to 41 Bq(.)kg(-1) for Ra-228 and from 59 to 227 Bq(.)kg(-1) for K-40. These levels are comparable to those appeared in coals of different countries worldwide. The activity concentrations of the examined fly ashes and produced in coal-fired power plants in Greece ranged from 263 to 950 Bq(.)kg(-1) for U-238, from 142 to 605 Bq(.)kg(-1) for Ra-226, from 133 to 428 Bq(.)kg(-1) for Pb-210, from 27 to 68 Bq(.)kg(-1) for Ra-228 and from 204 to 382 Bq(.)kg(-1) for K-40. The results showed that there is an enrichment of the radionuclides in fly ash relative to the input coal during the combustion process. The enrichment factors (EF) ranged from 0.60 to 0.76 for U-238, from 0.69 to 1.07 for Ra-226, from 0.57 to 0.75 for Pb-210, from 0.86 to 1.11 for Ra-228 and from 0.95 to 1.10 for K-40.