Naturally occurring radioactive materials (NORM) in ashes from a fuel-oil power plant in Cienfuegos, Cuba, and the associated radiation hazards

The radioactivity of NORM was measured in ashes collected from a fuel-oil power plant in Cienfuegos, Cuba, using an HPGe gamma-ray spectrometer. The Ra-226, Pb-210, K-40, Th-232 and U-238 activity concentrations reached 240, 77, 59, 70 and 15 Bq kg(1), respectively. The potential radiological hazard of these residuals was assessed. The radium equivalent activities of the samples varied from 54 to 345 Bq kg(1). The gamma index was calculated to be lower than that of the reference values, and the gamma absorbed dose rate was higher than the average reported for the earths crust; however, the assessed annual effective dose was slightly lower than the annual effective dose limit for public, i.e. 1 mSv. Therefore, these bottom ashes were not dramatically enriched with radionuclides and may be used as an additive for building materials without restrictions from a radiological protection point of view.