Natural radionuclide concentrations in soils around Baoji coal-fired power plant, China

Radionuclides are released together with fly ash from the coal- fired power plant and thus add to the natural radiation. Fifty soil samples were collected around the Baoji coal- fired power plant from 25 locations and the natural radionuclide concentrations were determined by a gamma ray spectrometric system. The results show that the activity concentrations in soil samples range from 12.54 to 40.18 Bq kg(- 1), 38.02 to 72.55 Bq kg(- 1) and 498.02 to 1126.98 Bq kg(- 1) for 226Ra, 232Th and 40K with the mean values of 27.35, 52.66 and 764.72 Bq kg- 1, respectively. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity ( Raeq), the absorbed dose rate ( D) and the annual effective dose rate have been calculated and compared with the internationally approved values. The radium equivalent activity in all the soil samples is lower than the safe limit set in the Organization for Economic Cooperation and Development report ( 370 Bq kg- 1). The average value of the calculated dose rates is higher than the global average value 55 nGy h(- 1), and the calculated annual effective dose rate is significantly lower than the average annual external effective dose rate ( 460 mu Sv y(- 1)) of the normal background radiation.