Innovation for advanced fuels at SRNL

HALEU and “TBD” materials

Uranium nitrate dissolved in solution. (Photo: SRNL/Tom Shehee)

SRNL conducted a study in 2019 that evaluated the potential for producing low-enriched uranium from the reprocessing of high-enriched foreign and domestic research reactor fuel at the H Canyon facility at the Savannah River Site. H Canyon previously produced LEU containing 4.95 percent by weight (wt%) uranium-235 from the reprocessing of surplus high-enriched uranium to make it usable to fabricate fuel for use in a commercial reactor. Though both timeline and volume capabilities were favorable, no contract for product was established at that time. In November of the following year, the DOE requested a similar report estimating potential capacity for HALEU production if the same facility and feedstock were used to produce 19.75 wt% U-235 solution. However, the shutdown of separations through H Canyon in 2022 left the previously recovered HEU solution as the only material remaining in the facility that had the potential to be used to produce HALEU.

As SRNL was assessing materials, the National Nuclear Security Administration’s Nuclear Materials Integration Division chartered the lab to lead a project seeking a solution for disposition challenges arising from the diverse nuclear material inventories across the DOE complex. This project culminated in a 2020 report that assessed specific DOE material inventories at each site to create a DOE-wide view of the major groups of materials categorized as having a “to be determined” disposition pathway. This study also considered projected future volumes of materials. Facility planning estimates were utilized for forecasting expected volumes of materials coming from research reactors and other sources with known disposition issues. Considering the impact of these future materials was critical for both safety and security purposes. The SRNL team developed a robust quantitative ranking system in 2023 that evaluated the options for disposition of each TBD material group. Though the initial purpose of this project was materials disposition, SRNL found value in the process of unpackaging and chemically processing some of the material.

SRNL engineer Cathy Ramsey was an integral part of both the TBD materials assessment and the initial HALEU feedstock estimates and proposals. “SRNL has a reputation as EM’s lab and of being the expert in disposition, but disposition doesn’t always mean disposal,” said Ramsey. “Irradiated nuclear materials offer opportunities to reprocess and recycle into new materials, and now is the time to really evaluate those opportunities. We need to have a longer view of the nuclear material life cycle than we’ve ever had before, which SRNL drives home in everything that we do.”

Though identification and management of both nuclear materials and their disposition pathways are key capabilities at SRNL, President Trump’s May 2025 executive orders centered on reinvigorating the nuclear industry cast light on supply chain and feedstock availability. SRNL rapidly identified the available inventory due to extensive evaluations conducted over the previous decade and was able to respond within days to requests for potential HALEU volumes that could be produced. The disposition study quickly became a production study. It was determined that additional material to meet our nation’s needs would be required beyond what was initially recovered.

The demand for fuel left SRNL with two questions:

1. If the separations at SRS’s H Canyon became operational, how much fuel could be created from the available supply of spent nuclear fuel from research reactors that is available on-site?

2. How much HALEU could be produced from nontraditional feedstocks identified through the TBD program at SRS and other federal nuclear sites?

LEU+

The Savannah River Site’s H Canyon facility. (Photo: SRNL)

The projected demand for HALEU far exceeds the supply, and numerous efforts are underway to mitigate the near-term supply shortfall. H Canyon is currently restarting the capability to produce HALEU from on-site HEU using natural uranium as blendstock. SRNL conducted a study that explored the potential to produce more HALEU from existing HEU stocks by using 9.75 wt% -U-235 enriched material (known as LEU+) as a replacement for the natural uranium.

During analysis of HEU solutions available at SRS, SRNL scientists measured concentrations of certain impurities for which fuel fabricators had provided specifications. While downblending with natural uranium lowered some impurity levels to meet specifications, the concept of LEU+ resulted from a mitigation strategy for the remaining high impurity levels. SRNL saw the opportunity to reduce the impurities while creating more HALEU by using LEU+, as opposed to natural uranium, for downblending. Compared with the baseline approach of making HALEU from existing natural uranium, the LEU+ approach nets roughly 3 metric tons more HALEU. The baseline natural uranium approach creates roughly 4 metric tons of HALEU as opposed to the nearly 7 metric tons for LEU+.

SRNL is collaborating with SRS’s management and operations contractor, Savannah River Nuclear Solutions, on production of the initial HALEU. If progress continues at the current rate, the first load of HALEU will be delivered to a fuel fabricator in the fall of 2027.

SRNL scientist Tom Shehee performs much of the materials characterization work for the HALEU program. “We will be giving the industry a shot in the arm to help get them going,” he said. “Fuel will require very tight specifications. What we have can meet that and also proves that we could reprocess other used fuels to create additional HALEU if desired.”

The costs to pivot to downblending with LEU+ instead of the natural uranium approach could offer increased efficiency of operational cycles and increased throughput with process optimization.

SRNL’s expertise in the back end of the fuel cycle has become incredibly valuable in establishing necessary feedstocks for the front end. The history of identification and characterization expertise in nuclear materials and innovative spirit of problem solving will lead the charge in establishing a secure future for nuclear energy technology. With an environmental stewardship mindset, SRNL does not limit its focus to front-end fuel supply needs; it also looks at strategy development for irradiated material and the reprocessing opportunities it holds, working to close the fuel cycle and make implementation of advanced reactors a reality for our nation.

Catelyn Folkert is an environmental management communications specialist at Savannah River National Laboratory.