A Closer Look at Uranium Tailings

The conventional process for uranium production starts with the extraction of uranium ore from a mine. After that, the uranium ore is physically and chemically processed in a mill where it is ground into a fine sand, allowing the uranium to be leached out and recovered. The remaining waste solids, known as “tailings”, are a complex mixture of minerals and precipitates, containing naturally-occurring radionuclides and other contaminants. Tailings must then be safely managed by isolating them from their surrounding environment.

The Canadian Nuclear Safety Commission (CNSC) has undertaken a research study which will significantly improve the understanding of the physical and chemical stability of uranium mill tailings, thus contributing to better techniques for their long-term management. The study will support existing research, as well as the development of more realistic geochemical and mineralogical models of how the various contaminants evolve in tailings management facilities. The findings of the study will also support regulatory licensing decisions on the decommissioning and remediation of operating and legacy uranium mines in Canada.

The CNSC’s Dr. Karina Lange and Dr. Steve Mihok collaborated on the supporting research with University of Chicago’s Dr. Tony Lanzirotti at the Advanced Photon Source (APS) research center located near Chicago, Illinois. The APS is a third-generation synchrotron facility with the brightest storage ring-generated X-ray source (a type of synchrotron light) in North America. Synchrotron light is highly valued because it enables the detailed study of molecular structures and, in this case, the exact forms of key radionuclides in uranium mine tailings of differing ages.

Drs. Lange and Mihok anticipate studying uranium tailings from various operating and legacy sites in Canada and plan to present their results at international fora.