A company called Lightbridge has developed a new type of nuclear fuel that runs 1,000°C cooler than standard reactor fuel. That’s a massive difference, and it could make nuclear power plants much safer and more efficient.
The fuel’s shape is key to how it works. Instead of plain cylindrical rods, Lightbridge uses a cruciform, or cross-shaped, pin design. That shape gives the fuel 35% more surface area to transfer heat.
The pins are also twisted in a spiral, which helps coolant flow around them more easily. The twisted pins touch each other every 10 centimeters, keeping the assembly stiff without needing extra support structures called spacer grids.
In a standard pressurized water reactor, the coolant runs at about 305°C. Lightbridge’s fuel operates at roughly 350°C at its center.
Standard fuel runs far hotter, which creates risks during accidents. With this cooler design, the peak cladding temperature stays hundreds of degrees below the point where zirconium reacts with water to produce hydrogen.
That reaction caused serious problems at Fukushima and Three Mile Island.
The fuel’s material also matters. It’s made from an approximately 50% uranium-zirconium alloy.
This metallic alloy conducts heat much better than the ceramic uranium dioxide used in most reactors today. There’s no gap between the fuel and its cladding, which reduces mechanical stress and keeps fission products from escaping.
The benefits don’t stop at safety. The design allows for higher power output, longer periods between refueling, and better ability to ramp power up and down.
That last feature’s potentially especially useful when pairing nuclear plants with wind and solar energy. This flexibility aligns with the broader push toward industrial decarbonization goals, as seen in projects like Dow Chemical’s partnership with X-energy to achieve reportedly significant CO2 reductions annually using small modular reactors.
Lightbridge received a U.S. patent for its metallic fuel assembly in June 2018. In March 2024, Idaho National Laboratory successfully demonstrated the fuel’s manufacturing process. Enfission, LLC, a 50-50 joint venture between Lightbridge and Framatome, holds exclusive rights to develop, license, manufacture, and sell fuel assemblies based on this technology. Lightbridge’s Utility Advisory Board includes senior fuel managers from four leading US utilities—Dominion, Duke, Exelon, and Southern—together representing 50% of the US nuclear generating fleet.
The company’s also working with Oklo on fuel fabrication facilities.
The fuel’s been tested in computer models for accident scenarios. In one simulation, the fuel reached only 50% of the maximum temperature seen in standard uranium dioxide fuel and cooled down ten times faster.
References
- https://www.ltbridge.com/investors/news-events/press-releases/detail/213/lightbridge-awarded-u-s-patent-for-metallic-nuclear-fuel-assembly-design
- https://atomicinsights.com/lightbridge-metallic-alloy-fuel-provides-upgrade-path-lwrs/
- https://www.powermag.com/lightbridge-oklo-to-explore-co-located-advanced-nuclear-fuel-fabrication-facilities/
- https://www.ltbridge.com/news-media/press-releases/detail/463/lightbridge-receives-notice-of-allowance-on-new-u-s-patent-for-its-metallic-fuel-assemblies-for-candu-reactors
- https://nuclearreview.substack.com/p/lightbridge-corp-designing-next-generation
- https://www.youtube.com/watch?v=9yyjGK429R8
