The influence of a coal-fired power plant operation on radionuclide concentrations in soil

Fifty-two soil samples in the vicinity of a coal-fired power plant (CFPP) in Figueira (Brazil) were analyzed. The radionuclide concentration for the uranium and thorium series in soils ranged from <9 to 282 Bq kg(-1). The range of 40K concentration in soils varied from <59 to 412 Bq kg(-1). The CFPP (10 MWe) has been operating for 35 years and caused a small increment in natural radionuclide concentration in the surroundings. This technologically enhanced natural radioactivity (TENR) was mainly due to the uranium series (234Th, 226Ra and 210Pb) and was observable within the first kilometer from the power plant. The CFPP influence was only observed in the 0-25 cm soil horizon. The soil properties prevent the radionuclides of the 238U-series from reaching deeper soil profiles. The same behavior was observed for 40K as well. No influence was observed for 232Th, which was found in low concentrations in the coal.