Y-12 cleanup project recovers, reuses mercury

January 28, 2021, 7:01AMRadwaste Solutions

Crews cleaned and demolished COLEX equipment on the west end of the Alpha-4 building at the Y-12 National Security Complex. Photo: DOE

The Department of Energy’s Oak Ridge Office of Environmental Management and its contractor UCOR have found a way to reuse instead of dispose of mercury collected from a cleanup project at the Y-12 National Security Complex, near Oak Ridge National Laboratory in Tennessee. “This questioning attitude and innovative thinking by our workforce is a major contributor to how our program is able to accomplish its projects under budget and ahead of schedule on a consistent basis,” said OREM manager Jay Mullis.

The DOE is conducting a number of projects to address mercury contamination—the most significant environmental risk is at Y-12, according to the agency. The work includes the cleanout and removal of equipment at Y-12's Alpha-4, a building that was used initially for uranium separation in 1944 and 1945. Ten years later, the building started being used for lithium separation, a process that required large amounts of mercury and involved column exchange (COLEX) equipment. Over the years, a significant amount of mercury from the process leached into the equipment, buildings, and surrounding soils.

Recovering Hg: Although the COLEX equipment was drained when operations ended at Alpha-4 in the 1960s, recoverable amounts of mercury remained in the aging lines and equipment that had rusted and deteriorated over the decades. Cleanup crews have so far retrieved more than 10,000 pounds of mercury, the DOE announced on January 26. As crews have retrieved the element, it was usually sent off-site to be treated for its subsequent storage.

New use: Recently, instead of being sent to interim storage, a batch of nearly 1,200 pounds was shipped to ORNL after being purified to laboratory-grade quality. It will be used by researchers in an experiment to determine physical properties for liquid metal flow. The data gained from this research will inform models for innovative concepts for material transfer and storage in a variety of fields.

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