Naturally occurring radioactive materials (NORMs) generated from lignite-fired power plants in Kosovo

The energy production in Kosovo depends primarily on lignite-fired power plants. During coal combustion, huge amounts of fly ash and bottom ash are generated, which may result in enriched natural radionuclides; therefore, these radionuclides need to be investigated to identify the possible processes that may lead to the radiological exposure of workers and the local population. Lignite samples and NORMs of fly ash and bottom ash generated in lignite-fired power plants in Kosovo are analyzed using a gamma-ray spectrometry method for the activity concentration of natural radionuclides. The average activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th in lignite are found to be 36 ± 8 Bq kg⁻¹, 9 ± 1 Bq kg⁻¹ and 9 ± 3 Bq kg⁻¹, respectively. Indications on the occurrence and geochemical behavior of uranium in the lignite matrix are suggested. The activity concentrations of natural radionuclides in fly ash and bottom ash samples are found to be concentrated from 3 to 5 times that of the feeding lignite. The external gamma-ray absorbed dose rate and the activity concentration index are calculated to assess the radiological hazard arising from ash disposal and recycling in the cement industry. - Highlights: • NORMs in lignite combustion residues from CFPPs are studied. • Th/U indicates either low U uptake from host rocks and/or high leaching from peat. • The concentration factor of NORMs in fly and bottom ash samples are 3–5 times. • No ²²⁶Ra enrichment is observed in fly ash while a depletion in bottom ash. • The reuse of fly ash in cement industry poses no significant radiological issue