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NMSU researchers work to minimize nuclear waste

A team of researchers from New Mexico State University and Los Alamos National Laboratory (LANL) is working to reduce the amount of nuclear waste destined for storage in nuclear repositories.

Amudhu S. Gopalan, head of the Department of Chemistry and Biochemistry at NMSU, and co-investigator Hollie Jacobs (not pictured) are leading a team working to reduce the amount of nuclear waste destined for storage in nuclear repositories. (NMSU photo by Darren Phillips)

S. Gopalan, head of the Department of Chemistry and Biochemistry at NMSU, and co-investigator Hollie Jacobs are leading a project titled "Development of Ligands for Nuclear Waste Separation Technologies." The research is receiving primary support from WERC: A Consortium for Environmental Education and Technology Development.

The United States has accumulated 44,000 metric tons of spent nuclear fuel rods, with an additional 2,000 metric tons generated annually. Typical nuclear energy production causes various byproducts to accumulate in fuel rods, which become exhausted after about two years of operation.

Some of these by-products, particularly cesium-137 and strontium-90, produce a considerable amount of heat due to nuclear decay. Because these isotopes have substantially shorter half-lives, separating them from the rest of the nuclear waste would result in a significant reduction of storage-bound nuclear waste.

It also would contribute to the goal of recycling spent fuel rods. Based on the nation's energy needs, the U.S. Department of Energy (DOE) has implemented the Advanced Fuel Cycle Initiative (AFCI) to develop methods for treatment of spent fuel rods and to reduce costs associated with geologic disposal. Ultimately, the aim of the AFCI is to develop a closed fuel cycle, providing a recycling system for fuel rods. Doing so would reduce the toxicity and cost of disposal as well as delaying or even eliminating the need for another geologic nuclear repository in the United States.

The nuclear energy industry currently employs an open fuel cycle in which fuel rods are merely stored at repositories. At today's rate of production, the capacity of the proposed geological repository at Yucca Mountain, Nev., is expected to be exceeded by 2015.

The technology being developed in Gopalan's project aims to improve the process used for separating cesium-137 and strontium-90 from other waste, by introducing new molecules that can extract specific elements and implementing strategies for environmental remediation. By providing technology for the recycling of spent fuel rods, the success of this project will play a key role in the development of a closed nuclear fuel cycle.

Gopalan and Jacobs are challenged with the design and synthesis of new molecules for the extraction of cesium-137 and strontium-90. The researchers are using a method enabling them to make and screen several of these molecules, called extractants, at once. Current methods are more labor intensive and expensive than the proposed method because they prepare and screen one extractant at a time.

"We are proposing a new class of molecules which have never been used before," Gopalan said. "The design and synthesis of these molecules is certainly the most challenging aspect of the project as a whole."

The identification of a cost-effective extractant will improve separation processes and will provide time-efficient alternatives. LANL collaborators will implement the technology to meet the needs of the DOE.

Once separated and purified, some elements of nuclear waste can re-enter the system for useful purposes. Americium is valuable because of its commercial use in smoke detectors. The reclaimed uranium can be recycled in new fuel rods.

"The success of this project will have long-lasting impact on current storage systems as well as the future of the nuclear industry," WERC Executive Director Abbas Ghassemi said.

Based at NMSU, the WERC consortium consists of NMSU, the University of New Mexico, the New Mexico Tech, Dine College and Los Alamos and Sandia National Laboratories. WERC's mission is to develop human resources and technologies for addressing environmental issues. For more information about WERC, visit www.werc.net or call (505) 646-2038.