Radioactivity of coals and fly ashes

The level and the behavior of the naturally occurring primordial radionuclides 238 U, 226 Ra, 210 Pb, 232 Th, 228 Ra and 40 K 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 238 U, from 44 to 255 Bq·kg −1 for 226 Ra, from 59 to 205 Bq·kg −1 for 210 Pb, from 9 to 41 Bq·kg −1 for 228 Ra and from 59 to 227 Bq·kg −1 for 40 K. 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 238 U, from 142 to 605 Bq·kg −1 for 226 Ra, from 133 to 428 Bq·kg −1 for 210 Pb, from 27 to 68 Bq·kg −1 for 228 Ra and from 204 to 382 Bq·kg −1 for 40 K. 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 238 U, from 0.69 to 1.07 for 226 Ra, from 0.57 to 0.75 for 210 Pb, from 0.86 to 1.11 for 228 Ra and from 0.95 to 1.10 for 40 K.