Abstract
The variable values of Ra-226, Ra-228 and K-40 were identified in coal and coal combustion residuals (CCR) samples to redistribute radionuclides using Ra-228/Ra-226 activity ratios in CCRs and compared to their values in the corresponding feed coal. NORM concentrations in CCRs were found to be 6-12 times higher than the original coal. The effective dose rates in the original coal were calculated and ranged from 14.9 +/- 0.9 to 370.3 +/- 22.2 mu Sv year(-1), whereas in CCRs ranged from 257.5 +/- 20.6 to 1797.5 +/- 143.8 mu Sv year(-1). The average concentration of K-40 (120 Bq kg(-1) per 1% K2O in CCRs) was calculated. The chemical composition indicates that the majority of CCR samples are Type C, which has a high calcium oxide ratio, high melting points and low deposition.