Measurement and spatial distribution pattern of natural radioactivity in a uranium tailings pond in Northwest China

Numbers of radioactive tailings were produced in the process of uranium mining and milling.In this study,radiation environment monitoring was carried out on a decommissioned uranium mining and milling tailings pond in northwest China, and the governance effect and operation status of the tailings pond was investigated. The soil radionuclide activity concentration and ambient dose equivalent rate (H*(10)) were measured, and soil surface radon exhalation rate was calculated. The results shown that in the tailings pond and its surrounding area, the average soil radionuclide activity concentration was respectively U-238: 42.64 +/- 11.17 Bq.kg(-1), Ra-226: 45.47 +/- 13.56 Bq.kg(-1), Th-232: 33.30 +/- 7.33 Bq.kg(-1), K-40: 631.33 +/- 72.05 Bq.kg(-1), the average H*(10) was 63.32 +/- 6.46 nSv.h(-1), and the average radon exhalation rate was 40.46 +/- 11.29 mBq.m(-2).s(-1).Radionuclide activity concentration, H*(10) and radon exhalation rate were within the range of world natural background. Spatial distribution of radioactivity was analyzed by OK interpolation based on the investigated data. According to the measured results and spatial interpolation analysis,the decommissioning governance effect of the uranium tailings reservoir is good, the operation is normal, and there is no migration or diffusion situation of radionuclides in the pond has been found.