RESUMEN
Natural uranium is a crucial resource for clean nuclear energy, which has brought significant economic and social benefits to humanity. However, the development and utilization of uranium resources have also resulted in the accumulation of vast amounts of uranium mill tailings (UMTs), which pose a potential threat to human health and the ecological environment. This paper reviews the research progress on UMTs treatment technologies, including cover disposal, solidification disposal, backfilling disposal, and bioremediation methods. It is found that cover disposal is a versatile method for the long-term management of UMTs, the engineering performance and durability of the cover system can be improved by choosing suitable stabilizers for the cover layer. Solidification disposal can convert UMTs into solid waste for permanent disposal, but it produces a large amount of waste and requires high operating costs; it is necessary to explore the effectiveness and efficiency of solidification disposal for UMTs, while minimizing the bad environmental impact. Backfilling disposal realizes the resource utilization of solid waste, but the high radon exhalation rate caused by the UMTs backfilling also needs to be considered. Bioremediation methods have low investment costs and are less likely to cause secondary pollution, but the remediation efficiency is low, it can be combined with other treatment technologies to remedy the defects of a single remediation method. The article concludes with key issues and corresponding suggestions for the current UMTs treatment methods, which can provide theoretical guidance and reference for further development and application of radioactive pollution treatment of UMTs.
RESUMEN
Compacted soil layer (CSL) is generally designed for uranium mill tailings (UMTs) pond to form the radon seals, whereas it is usually affected by drying-wetting environmental conditions. To summarize the radon attenuation degradation performance of CSL subjected to drying-wetting cycles, an experiment with the application of meteorological data was developed. This paper focuses on the evolution of the soil apparent porosity, soil integrity and radon attenuation characteristics of CSL during continuous drying-wetting cycles. Image processing and a nonmetal acoustic wave detector were applied to analyze variations in the soil surface and internal defects, and the radon concentration was measured to reveal the radon attenuation performance of the CSL. The results reveal that with successive drying-wetting cycles, the soil apparent porosity increased, and the soil pores were enlarged. The soil integrity underwent dynamic recombination or reorganization and eventually reached a steady state. Moreover, it was observed that the saturated state of the uppermost soil led to a sharp increase in radon concentration (capping effect), and the decrease in accumulated radon concentration during the initial period resulted from the coupling effect of soil moisture, temperature and ambient pressure. The observations confirm that the drying-wetting environmental conditions markedly affect the radon migration channels and environment in the CSL, which provides a theoretical foundation for UMTs pond governance and radiation safety management.