In-situ leaching uranium technologies has been widely used in the mining of sandstone uranium mines, and the potential environmental impact of in-situ leaching process on groundwater has always attracted wide attention from societies. This author summarized the progress of experimental researches on groundwater remediation technology at in-situ leaching uranium mines and analyzed the remediation technologies and effects of groundwater remediation cases on in-situ leaching uranium mines worldwide. The results show that the pump and treat technology with high restoration efficiency and short cycle repaired costly, and the continuous release of pollutants in the aquifer solid medium can lead to restoration rebound and tailing in the late restoration period. The natural attenuation technology has remarkable repair effect on both radioactive and non-radioactive elements. However, long remediation period and long-term monitoring of repair effect limited its applications. Therefore, the application of a single repair technology can be restricted by various factors, combining multiple remediation technologies, and different technologies in different repair stages will be applied in future. Combining the pump and treat technology and the natural attenuation technology can be considered as a groundwater remediation scheme in China.

The optimal selection of uranium tailings sand cover materials is of great significance to the management of tailings sand in uranium mines. By constructing a radon concentration distribution model for uranium tailings sand cover layer, using single-layer and three-layer cover materials, constructing a multi-objective decision model with radon emanation rate and comprehensive cost as decision objectives, and finding the optimal solution of feasible solutions based on multi-objective non-dominated ranking method. For uranium tailing sand, if single-layer covering material is used, only three materials, namely clay, cement mortar and asphalt, can meet the national standard limit value of radon emanation rate within a reasonable thickness range; compared with single-layer covering material, the radon emanation rate outside the three-layer covering material meets the national standard limit value requirement and the comprehensive cost is reduced by 75.9%.

In the numerical simulation of atmospheric diffusion of pollutants characterized by radon, the default values of wet deposition parameters are generally adopted, which leads to the uncertainty of calculation accuracy. In order to determine the influence factors and characteristic values of radon wet deposition parameters, a self-developed experimental device was used to simulate the precipitation process, and the response relationship between initial radon activity concentration, precipitation intensity, precipitation pH and radon wet deposition rate and removal efficiency was comprehensively analyzed. The results show that the wet deposition rate of radon in atmospheric environment is linearly correlated with the initial radon activity concentration and precipitation intensity (R²>0.99), while the removal efficiency is weakly correlated with the initial radon activity concentration and pH value. Therefore, taking gaseous radon as a typical object, when the wet sedimentation rate is in the range of 31~2 653 Bq/(m²·h), it can be predicted that the removal efficiency of radon will remain at 0.55%~0.65%. The relationship between the final precipitation intensity and wet deposition parameters follows exponential function. The conclusion can provide parameter basis for numerical simulation of atmospheric diffusion of radon.

Based on the geological conditions and surrounding environmental survey results of the open-pit mine waste dump slope deformation monitoring, using the Beidou high-precision positioning technology, five Beidou displacement monitoring points were set up on the 1590, 1586 and 1580 platform slopes of the waste dump, and the real-time monitoring of the slope deformation of the waste dump was achieved. The statistical analysis of deformation monitoring data for 10 consecutive months shows that the construction of the waste dump has led to the vertical deformation of the slope at each monitoring point. The vertical deformation of the 1590 platform slope is significant, with the average monthly cumulant of deformation about 6.0 mm, and the average monthly cumulant of the vertical deformation of other platform slopes is less than 3.0 mm. No acceleration or step change of deformation has occurred at each monitoring point, and the waste dump slope is still in a stable period. The application of Beidou satellite system in displacement monitoring of waste dump provides automated monitoring methods and raw monitoring data for slope deformation trend prediction and safety warning, ensuring the safety of open-pit mine waste dump stacking operations.

A UO₂ pellet development laboratory is planning to be decommissioned, in order to know the radioactive contamination inside the laboratory, a preliminary source terms survey was carried out, including the operation history, surface pollution level, γ radiation dose level, aerosol concentration level investigation, as well as the contaminated area and pollutant items estimation. The results show that the main contamination nuclides are ²³⁴U, ²³⁵U and ²³⁸U, the radioactive contamination nuclides are single. The surface contamination level and the γ radiation dose and the aerosol concentration in the radioactivity laboratory is low. The contaminated area of the ground and wall of the experimental building is about 1 000 m², about 300 units of equipment need to be decontaminated, and the temporary storage of radioactive solid waste is about 80 m³. Due to a wide variety of pollutants, and the pollution degree of various pollutants varies greatly, the solid waste should be classified during decommissioning treatment to prevent cross-contamination of various pollutants.

Since the implementation of the management regulations of funds for the decommissioning of nuclear facilities and the treatment of radioactive waste, the management of project funds has been effectively standardized. Through the analysis of the calculation of related expenses for the decommissioning of nuclear facilities and the treatment of radioactive waste projects, it has been found that there are certain issues that need to be addressed, such as the lack of applicable regulations for the transport and disposal of waste, inconsistencies in the calculation of labor costs, discrepancies in related expense rates, and the absence of consideration for the cost of self-raised funds for projects that are implemented ahead of schedule. Recommendations for revisions have been provided for these issues.

The use of isotopes are becoming more and more common in imaging, diagnosis and treatment, which bring potential radiation hazards to radiation workers and the public. By exploring the radiation protection measures of the nuclear medicine discipline, based on the monitoring and analysis of the current situation of the nuclear medicine discipline in a hospital and the field investigation, the radiation protection effect of the radioisotope application site in the hospital was analyzed and evaluated. The results show that the radiation level around the radiation workplace of the nuclear medicine department is lower than the dose limit specified in the standard, and the estimated annual effective dose is less than the management target value, which meet the relevant standards of radiation protection. The shielding effect of the shielding body in various places of the hospital is good, and the shielding of the nuclear medicine institute is feasible.

The characteristics of surface uranium mineralization, ore characteristics and uranium geochemistry in the southern Weijing area, Siziwang Banner, Inner Mongolia were described, the geochemistry characteristics of constant, trace and rare earth elements in the NE-trending ore-bearing structures were studied. The results show that the uranium mineralization is closely related to the adsorption of gelatinite and ferric oxide, and the U is positively related to P₂O₅. According to the characteristics of uranium mineralization, the genesis of uranium mineralization is discussed, and it is considered that the ore-bearing hydrothermal solution rises along the structure to a special redox interface, after unloading, the uranium enters into the crystal lattice of apatite by isomorphism, and forms uranium-rich gelophosphate, at the same time, heavy rare earth and strontium are enriched and precipitated together.

At the later stage of production in the uranium mining area, the metal production usually continues to decline, and the metal concentration also changes with the influence of the intensified leaching process. At this time, the production cannot be accurately calculated by the liquid pumping volume and the concentration. Based on the induction and analysis of production parameters, a multiple linear regression model and an artificial neural network model are established for the prediction of daily metal production in a single mining area. The results show that both of them have good accuracy and generalization ability, the effect of artificial neural network model is better, the average error of metal daily production prediction is only -0.36%, the outliers are less and the error distribution is balanced. The accuracy of this method is significantly improved compared with the simple calculation to obtain the daily metal production. The use of artificial neural network model to predict the production of the mining area can provide solutions and theoretical guidance for the adjustment and change of leaching process and production system.

Filtering mechanism and effect of many kinds of filters have been systematically studied. Assuming that the particles are spheroid of equal size and arranged in an inclined cube, the initial minimum pore diameters of gravel filter and porcelain granule pre-coated filter are calculated to be 0.310 and 0.155 mm, respectively. Because of the filtration effect, the pore diameter of gravel filter and porcelain granule pre-coated filter gradually decreases with the extension of time, and the filtration effect is good. The diameter of the hole of the filter without gravel and wrapped with mesh is 0.180~0.270 mm, and the diameter is basically the same after assembly, this filter only has the effect of blocking, and the filtering effect is poor. The hole wall of the filter without gravel or with uncompacted filling may collapse or fall out of sand, and there are too many debris in the leaching solution. Mercury injection test shows the maximum pore throat diameter in sandstone uranium deposit is 0.032 mm, and all filters have no barrier effect on unstable silty clay debris and chemical precipitation.