Natural radionuclides in waste water discharged from coal-fired power plants in Serbia

Investigation of the natural radioactivity levels in water around power plants, as well as in plants, coal, ash, slag and soil, and to assess the associated radiation hazard is becoming an emerging and interesting topic. This paper is focused on the results of the radioactivity analysis in waste water samples from five coal-fired power plants in Serbia (Nikola Tesla A, Nikola Tesla B, Kolubara, Morava and Kostolac), which were analyzed in the period 2003-2015. River water samples taken upstream and downstream from the power plants, drain water and overflow water were analyzed. In the water samples gamma spectrometry analysis was performed as well as determination of gross alpha and beta activity. Natural radionuclide ⁴⁰K was detected by gamma spectrometry, while the concentrations of other radionuclides, ²²⁶Ra, ²³⁵U and ²³⁸U, usually were below the minimum detection activity (MDA). ²³²Th and artificial radionuclide ¹³⁷Cs were not detected in these samples. Gross alpha and beta activities were determined by the α/β low level proportional counter Thermo Eberline FHT 770 T. In the analyzed samples, gross alpha activity ranged from MDA to 0.47 Bq L^-1, while the gross beta activity ranged from MDA to 1.55 Bq L^-1.