TRISO-X begins construction on commercial-scale advanced nuclear fuel facility

Article by Kerry Hebden

X-energy's Xe-100 four pack nuclear plant
One of X-energy's Xe-100 four pack nuclear plants

TRISO-X, a wholly-owned subsidiary of X-energy, has marked the start of construction at a site its parent company has billed as “North America’s first commercial-scale advanced nuclear fuel facility” in Oak Ridge, Tennessee.  

Known as the TRISO-X Fuel Fabrication Facility (TF3), the plant will manufacture TRi-structural ISOtropic (TRISO) fuel – incredibly small and robust particles made up of a uranium, carbon and oxygen fuel kernel. The kernel is wrapped in three alternating layers of pyrolytic carbon and silicon carbide, and more than 18,000 TRISO-X particles are embedded in a graphite fuel pebble, making the fuel “meltdown proof.”  

Currently, most existing nuclear reactors around the world run on low enriched uranium, fuel that is enriched up to 5% with uranium-235 (U-235). Only a few nuclei are known to undergo fission, and U-235 is one of them. After a U-235 nuclei absorbs an extra neutron, it can cause it to become unstable and quickly break apart, and when it does, it releases energy and two or three neutrons. This in turn can enable a fission chain reaction to be sustained. 

TF3 is described as a High-Assay, Low-Enriched Uranium (HALEU) fuel fabrication facility. HALEU is uranium that has been enriched so that the concentration of U-235 is between 5–20% of the mass of the fuel. By using a higher concentration of fissile U-235, advanced reactors can be smaller, and as they get more power per unit of volume, fuel efficiency is increased. 

“The fuel X-energy will produce at this Oak Ridge facility will build a more robust and secure nuclear energy supply chain – supporting the deployment of nuclear energy on a scale never seen before,” said Pete Pappano, President of TRISO-X.  

The TF3 Facility is being commissioned through funding, in part, from the US Department of Energy’s (DOE) Advanced Reactor Demonstration Program (ARDP), which two years ago awarded X-energy US$80m to build two advanced nuclear reactors that can be operational within seven years.  

Scheduled for startup as early as 2025, the TF3 is projected to generate more than 400 jobs to the Oak Ridge area and attract an investment of nearly US$300m.  

The facility will initially produce 8 t/y of fuel that can support about 16 TRISO-fuelled advanced reactors of different designs or 12 of X-energy’s Xe-100 high-temperature gas-cooled reactors. The Xe-100 is 80 MW reactor that can be scaled into a “four-pack” 320 MW power plant configuration. The TRISO-X team said it aims to expand the facility’s capacity to 16 t/y by the early 2030s. 

X-energy expanded TRISO-X as a subsidiary to commercialise its advanced nuclear fuel in 2021. “The nuclear energy industry is on the cusp of a paradigm shift that will be driven by advanced reactors like the Xe-100,” J Clay Sell, the CEO of X-energy said at the time. “Many of the next-generation reactor designs are powered by TRISO fuel, and meeting this demand will require new supply chains and fabrication processes.” 

TRISO-X is also advancing plans for a second fuel fabrication facility in Canada to serve the Canadian market, the firm said. Meanwhile, X-energy recently teamed up with Intuitive Machines under a joint venture called IX to provide a solution to deliver fission surface power to the Moon by 2028. The partnership won US$5m in funding from the DOE and NASA to conduct a one-year study to mature the design of a system that will deliver at least 40 KW to power a habitat, rover and even mining operations on our nearest celestial neighbour.  

Article by Kerry Hebden

Staff reporter, The Chemical Engineer

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