Abstract:Based on High-Purity Germanium Gamma Spectrometer, radioactive concentrations of natural radionuclides 238U, 226Ra, 232Th and 40K in discharged water and surrounding surface water of uranium tailing and mill were accurately measured to investigate pollution to external environment and risk to health of nearby residents. The results show that contents of 238U, 226Ra, 232Th and 40K in percolating water of tailing and discharged water of mill are significantly lower than those in internal water, the total uranium content in percolating water of tailing is 0.23 mg/L and the specific activity of 226Ra is 0.68 Bq/L, both of which are lower than the national standard (GB23727-2009). The total uranium content of water discharged from the mill is 1.37 mg/L, and the specific activity of 226Ra is 1.37 Bq/L, both of which are higher than the national standard. If the water in middle and lower reaches of the tailing canals and the water from the mill which entered the river in residential area are used as drinking water, the total committed effective dose of 238U, 226Ra and 232Th to human is 0.187 5 and 0.121 4 mSv/a respectively, both of them exceed WHO guidelines for drinking-water quality. Comparing with contents of 238U, 226Ra and 232Th in water with the local background value, the surface water in the study area is polluted.