Radionuclide content of NORM by-products originating from the coal-fired power plant in Oroszlány (Hungary).

At the Thermal Power Plant in Oroszlány (Hungary), a huge amount of by-products have been produced since 1961. In this survey, coal and other by-products were examined (fly ash, bottom ash, fluidised bed bottom ash, gypsum and slurry-type ash). The natural isotopes were determined using an HPGe detector. It was found that the radionuclide content of coal was significantly lower (²²⁶Ra = 45.3±6.3, ²³²Th = 26.3±5.7 and ⁴⁰K = 210±21 Bq kg⁻¹) than that in the case of ashes other than the fluidised type. The average values of the bottom ash—deposited in the largest quantities—were three times higher than those for coal (²²⁶Ra = 144±18,²³²Th = 84.3±14 and ⁴⁰K = 260±25 Bq kg⁻¹). In the case of fractionised bottom ash, the radionuclide content of <0.1 mm was 45 % higher than that of >1.6 mm and the massic radon exhalation of <0.1 mm was approximately four times higher than that above this range.