FUEL & FUEL CYCLE | ADVANCED FUELS
An advanced fuel for LWR and SMR designs
An advanced nuclear fuel designed for use in water-cooled nuclear power plants and Small Modular Reactors (SMRs) offers a wide
range of simultaneous improvements in safety, fuel performance, power plant economics, waste reduction, and proliferation resistance
By Dr. Scott Holcombe, Dr. Andrey Mushakov, and James Fornof, Lightbridge Corporation
THE NUCLEAR FUEL USED IN NPPs today has changed little since the initial deployment of nuclear power more than half a century ago. The fuel design for water-cooled reactors since the dawn of the nuclear power industry has been based on ceramic uranium oxide (UO2
) fuel pellets, enriched
to less than 5% U-235, contained in zirconium-alloy cladding tubes.
While continuous incremental improvements have been made on this basic fuel design, and modern commercial nuclear fuel outperforms the original fuel, modern fuel still consists of the same basic design elements of UO2 fuel pellets contained in zirconium-alloy cladding tubes. Incremental advancements in the performance of this fuel design may continue, but far-reaching advancements in commercial nuclear fuel performance will likely require fundamental changes. Conversely, Lightbridge’s advanced metallic fuel rod design, being developed for use in existing water-cooled
reactors and water-cooled SMRs, is fundamentally different than current fuel and offers a host of simultaneous step- change improvements. Lightbridge metallic fuel rods are multi-lobed and
helically twisted, consisting of a metallic uranium-zirconium alloy fuel core, that is co-extruded and metallurgically bonded to a zirconium-alloy cladding, and a central zirconium-alloy displacer that can be alloyed with burnable poisons.
The fuel core is an alloy consisting of approximately
50% uranium and 50% zirconium by weight. The uranium component of the fuel alloy can be enriched up to 19.75% U-235. Enrichment above 5% and below 20% is known as High-Assay Low-Enriched Uranium or HALEU. The cladding is composed of a zirconium alloy that is standard in conventional nuclear fuel. The helically twisted design provides self-spacing of the rods in a fuel assembly, eliminating the need for spacer grids.
Above: Lightbridge Fuel’s design enables nuclear plant performance improvements Source: Lightbridge 34 | October 2023 |
www.neimagazine.com
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