Background

Uranium mill tailings are sand-like materials left over from the separation of uranium from its mined ore. More than 99% of the ore becomes tailings. The U.S. has been dealing with this issue for several years, as have many other nations. To discuss this subject participants from Argentina, Brazil, Canada, South Africa, Australia, Germany, and the U.S. held a technical discussion and facility tour in Colorado from June 6-14, 1997. The focus of the meeting was DOE’s Uranium Mill Tailings Remedial Action (UMTRA) project, which is near completion, and how UMTRA knowledge could be applied to CNEA sites.

UMTRA is the world’s largest materials management project ever undertaken to reduce or eliminate risk to the public from exposure to potentially hazardous and radioactive materials. This project, comprised of both surface clean-up and groundwater compliance phases, details the responsibilities for encapsulating and isolating almost one-fourth of all the uranium mill tailings generated across the entire U.S. (more than forty-four million cubic yards). The UMTRA project manages the cleanup of 24 former uranium ore processing sites contaminated with tailings and other waste from uranium milling operations. In addition to the processing sites, remediation has also been completed at more than 5,000 "vicinity properties," in which tailings had been used off-site for construction or landscaping purposes.

Argentina faces similar mill tailings problems as the U.S., however on a much smaller scale. Mining of uranium ore deposits began there in the 1950s, at sites that were often adjacent to populated areas. As such, windblown (airborne) and groundwater contamination have been issues of concern. Argentina has seven mill sites of which only one is still operational. CNEA is currently dealing with the issue of how to treat and where to store these mill wastes.

Two Argentine sites considered for final disposal are the Malargue and Cordoba Facilities. It has been noted that the Malargue Facility has several similarities to the DOE site in Gunnison, Colorado, which has been remediated under the UMTRA program. Consequently, CNEA officials have voiced interest in further investigation of the clean-up proceedings at Gunnison. As in the U.S., Argentina has considered in-site or off-site disposal options. Site characterization, planning, chemical make-up of tailings, the pH of tailings and the decision to neutralize (or not) tailings during disposal, long-term care, and custody of disposal cells are all topics of interest to the Argentine scientific community.

Activities

In June of FY97, a CNEA representative participated in a DOE-sponsored site tour of DOE’s uranium mill tailings sites in Colorado and Utah. As a result of this exchange, CNEA is re-evaluating their current methodology of remediating Argentine uranium mill tailings.