- Savannah River National Lab Tackles Nuclear Fuel Challenges for SMRs and Microreactors
- SRNL Receives $6M to Lead Projects Advancing Fusion Energy Research
Savannah River National Lab Tackles Nuclear Fuel Challenges for SMRs and Microreactors
In a wide ranging interview with Bill Bates, SRNL Deputy Associate Laboratory Director, Environmental and Legacy Management, he explained the challenges ahead as SMRs and microreactors come to market and how SRNL is working to meet them.
Small modular reactors are a key part of the Department’s goal to develop safe, clean and affordable nuclear power options ranging in size from tens of megawatts up to hundreds of megawatts, offering many advantages over larger nuclear plants including smaller physical footprints, lower capital investment, siting in locations not possible with larger plants, and provisions for incremental power additions.
Conversations about small modular reactor deployment need to include discussion about the fuel cycle and backend. Policies and plans will follow along with development of technologies to carry them out.
Bates says the starting point is that, “Our experience is with development and application of modular approaches to nuclear materials processing. The ability to provide right-sized process capabilities is very applicable to the emerging fuel cycles associated with advanced small modular reactors.”
According to Bates, discussions about advanced small modular reactors can’t stop with the reactor deployment those conversations need to include discussion about the fuel cycle.
“It’s more than just the new reactor, it’s about the fuel, it’s about how you deal with the reactor itself when you’re done and it’s about how you deal with the spent nuclear fuel. SRNL has experience in all of that.”
There are challenges that come with the deployment (and demobilization) of an advanced small modular reactor (or microreactor) to a battlefield or to a location impacted by a natural disaster like a hurricane or earthquake.
“Here, we’re talking about having to move spent nuclear fuel and highly irradiated material, and very likely the reactor itself,” said Bates. It is those backend process challenges that Bates believes are only starting to get attention.
HALEU Production
“Our packaging and transportation group is also working with Orano (under the same scope) on licensing a shipping package to be able to ship the HALEU in a liquid form to the fuel fabricator who will use this high-assay low enriched uranium to produce fresh reactor fuel,” Bates said.
“The project demonstrates our expertise in packaging and analytical capabilities to support the initial feedstock for advanced small modular reactors of the near future.”
What to Do About the Tubs?
In the area of D&D for SMRs and microreactors, there is a challenge for dealing with designs that put the entire reactor in a “tub” that is replaced every five-to-ten years.
“Where does it go,” Bates asked.
Bate adds there are two pathways for D&D of these reactors. The first is to separate the spent fuel from them for possible future use or for permanent disposition in a geologic repository.
Disposition of Spent TRISO Fuel
“TRISO fuel uses graphite as its cladding and moderator and SRNL has several patents on a technology for removal of that graphite,” said Bates.
“We’re working to optimize that technology to allow for modular processing for recovery of HALEU from fresh fuel scrap during fuel fabrication or for treatment of spent nuclear fuel.”
SRNL was recently awarded a DOE Office of Technology Transitions project in which SRNL is partnering with the University of South Carolina.
“The removal of the graphite from the spent TRISO fuel enables either the reprocessing of the spent fuel or a reduction of the volume of high-level waste requiring packaging, storage, transport and disposal. This is possible because SRNL’s process technology removes more than 90 percent of the fuel volume. In the processing, some neutron poison material is added back in but the final overall volume reduction of material is about 60 percent.”
Bates notes that the elimination of the graphite yields carbon dioxide, but the work the lab is doing with the University of South Carolina aims to capture the CO2 and convert it into a solid form allowing it to be disposed of as low level waste.
“Our solution is an elegant way to process spent TRISO fuel, compared to many other approaches that have numerous challenges including grinding, burning, and cutting of graphite.”
Developing the Future of Spent Fuel Disposition Pathways for New Reactors
Ultimately, SRNL knows that the reality is developers of SMR and microreactors have to come to terms with the spent fuel pathways for their respective designs.
“You can preserve the spent fuel to reuse it, in which case it would be packaged and kept intact for potential future use or isotope recovery, or you can stabilize it intact or process it into a waste form, and then package it for storage as a high-level waste.”
Savannah River National Laboratory is a United States Department of Energy multi-program research and development center that’s managed and operated by Battelle Savannah River Alliance, LLC (BSRA) for the Department of Energy’s Office of Environmental Management.
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SRNL Receives $6M to Lead Projects Advancing Fusion Energy Research
The projects focus on challenges in fuel cycle and blanket technologies, and tritium interactions with materials. The two projects receiving funding include:
1) Non-Aqueous 2-D Material Based Hydrogen Isotope Separation, led by principal investigator Dale Hitchcock; and
2) Development and De-risking of Li Electrolysis and CoRExt Process by Flow-Loop Integration, led by principal investigators Luke Olson and Christopher Dandeneau.
“Both projects will develop novel technologies invented at SRNL and provide the resources to increase the technology readiness level of the methods,” said SRNL Advisory Program Manager, Fusion Energy, Brenda Garcia Diaz.
Most concepts for commercial fusion power will use deuterium and tritium fuel. In those devices the isotopic makeup of the fuel inside the reactor is critical to maintain a burning plasma. As such, hydrogen isotope separation is a critical technology for a commercially viable fusion power plant.
Traditional techniques for hydrogen isotope separation are energy intensive, require low temperatures, a large footprint, or some combination of the three. The 2D isotope separation project proposes to develop a continuous and more energy efficient method for hydrogen isotope separation based on 2D material coated solid state proton conducting ceramics.
“Isotope separation is a slow and expensive process,” said Hitchcock. “Our patented technology using 2D materials to separate hydrogen isotopes could significantly reduce the capital and operational costs associated with tritium processing in a fusion power plant.”
Fusion reactors will need to make and extract their own tritium fuel to be sustainable. Research led by principal investigators Luke Olson and Christopher Dandeneau seeks to simplify and reduce costs for extracting tritium from two leading fluids the fusion community and many private fusion startups are investigating.
Tritium extraction technologies that SRNL have shown to work on benchtops will be scaled up to better match expected fusion plant conditions through partnerships with Idaho National Laboratory and with Oak Ridge National Laboratory.
“The scale-up of these tritium separation methods for use in molten metal and molten salt tritium breeders will significantly de-risk and improve the technology readiness levels of these SRNL developed methods, said Olson. “They have the potential to significantly simplify and improve tritium separation compared to the status quo.”
“The tritium extraction methods developed by SRNL are dependent on durable materials operating in harsh, corrosive environments,” said Dandeneau. “Interactions of these materials with tritium, lithium and molten salts can greatly reduce operating lifetimes. Our team will leverage expertise at SRNL in creating new materials that can tackle these challenges.”
The Laboratory Foundational Science Programs in Fusion Materials, Nuclear Science, and Enabling Technologies span functional and structural materials for heating technology, magnet technology, blankets, fuel cycle, and first wall. The purpose of the funding is to address scientific gaps foundational to enabling fusion energy, and reorient the laboratory-based foundational and basic science research programs to better align and support the new Fusion Energy Sciences program vision.
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