Geostress measurement is a necessary prerequisite for determining the attributes of engineering rock body mechanics, analyzing the stability of the surrounding rock, and realizing the scientific excavation design and decision-making of rock engineering. With the depth of mining of Mianhuakeng mine, the impact of complex structural stress on the stability of the lane roads and lying surrounding rocks has become increasingly apparent. In order to master the terrain distribution of the rock body in the deep part of the mine and improve the scientific, safety and economic rationality of the underground engineering design, the hollow inclusion stress relief method is used to carry out the stress measurement of the mine, and analyze its stress status and distribution rules. The results show that the maximum main stress is between 22.5 and 29.8 MPa and the ratio of the maximum main stress to vertical stress is 1.5 ~ 1.7 in the buried depth of 615~715 m. The main stress increases linearly with the depth and the maximum main stress direction of each measurement point level is in the direction of from 91.2 to 110.3° (North West West-South East East), which has a strong consistency.

Deep-hole blasting is used in the mining of hard rock uranium ore in Mianhuakeng mine, the blasting parameters are derived from the experience value of the diameter of the blasting hole, which has the problem of low blasting quality. The optimum depth and radius of 300 g charge are 0.65 m and 0.63 m respectively from the single hole blasting crater test, the optimum distance between holes is 0.9~1.0 m and its ratio to the optimum crater radius is 1.43~1.59 from the multi-hole blasting test with variable hole spacing, the optimum minimum resistance line from the slope step blasting is 0.41 m. Based on the blasting similarity law, the optimum hole spacing of 65 mm deep hole is calculated to be 1.7 m. Considering that the test results of slope step blasting are not ideal, the empirical value of hole bottom density coefficient of fan-shaped hole layout is 1.0~1.3, and the row spacing of deep-hole blasting is recommended to be 1.3 m after calculation.

A lead-zinc mine is exploited by adit+shaft+slope path, and mined by sublevel open stope method and shallow hole retaining method. This method has large exposed area and poor safety, and the goaf formed by stope has buried hidden danger for mine production. With the increase of depth, the stability of surrounding rock becomes worse, the ore body becomes thinner and more dispersed, resulting in the increase of mining dilution rate and the extremely high mining and mineral dressing cost, and the original mining method is no longer applicable. According to the characteristics of ore body and the current production situation of the mine, the mining of the ore body below the middle level of 2 522 m adopts application of mechanized upward horizontal slicing and filling mining method, and uses large trackless equipment to carry out mining operations, which reduces the exposed area of the stope, improves the safety of underground operation, avoids a large number of goaf, solves the hidden danger in production and improves the recovery rate of resources. The production capacity, comprehensive recovery rate, comprehensive dilution rate and other indicators are optimized. The research results can be used as an example for other mines in this area.

An on-line analyzer was developed for the determination of carbonate and hydrogencarbonate concentrations in the tail liquid of a fluorine-leaching agent by titrimetry with the electrode measuring pH as the end point, the chemical principle, hardware composition, determination program and other functions of the instrument were introduced. The alkalinity of 0.01~1.00 mol/L was determined by the instrument. The repeatability error is 1.5%, the accuracy error is 4.8% and the lower detection limit is 0.04 mol/L. The results of field test show that the instrument has good stability and high precision, and the measured data are basically consistent with the on-site titration analysis data, which meets the requirements of on-site analysis. The recovery rate of spiking is between 96.0% and 104.0%.

With the development of uranium mining and milling industry, the number of uranium tailings pond is increasing. It has potential harm to the surrounding environment. Therefore, exploring an environmental and effective way to control the pollution sources is to be imminent. Uranium tailings pond covering technology is an effective method recognized at home and abroad, and is also the main technology used in most practical projects at present. The status of uranium tailings pond covering technology at home and abroad is reviewed, the common materials, technical measure, and the governance effectiveness of decommissioning uranium tailings pond are described, in order to provide reference for the surface covering engineering technology of uranium tailings pond.

As a new type of organic porous material, covalent organic frameworks are widely used in environmental field because of their large specific surface area, ordered pore structure and controllable scaffolds, such as adsorption, separation and photocatalytic degradation of pollutants. The removal of radioactive contamination in the environment by covalent organic framework-based materials is reviewed, and the research progress of removal of uranium, europium, thorium, technetium and iodine by covalent organic framework-based materials is discussed.

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.