TRISO-X, a subsidiary of X-energy, has begun the interior construction phase of its TX-1 facility in Oak Ridge, Tennessee. Clark Construction Group will lead the interior fit-out of the 214,000-square-foot complex, overseeing the installation of fuel manufacturing equipment and the construction of an adjacent building dedicated to graphite matrix powder.
At full capacity, TX-1 will produce 700,000 TRISO-X fuel pebbles per year, equivalent to 5 metric tons of uranium — enough to power up to 11 Xe-100 reactors. Each pebble — roughly the size of a billiard ball — contains more than 18,000 TRISO particles, each no larger than a poppy seed. The fuel features layered carbon and ceramic coatings designed to withstand extreme temperatures without releasing radioactive material. The facility sits on a 110-acre campus within the Horizon Center Industrial Park and is expected to employ approximately 500 full-time workers.
Vertical construction of the building began in November 2025. In February 2026, the Nuclear Regulatory Commission granted TRISO-X a 40-year special nuclear materials license — the first NRC Category II license ever issued for the processing of high-assay low-enriched uranium (HALEU), and the first new commercial nuclear fuel fabrication license in more than 50 years. A double milestone that underscores just how stagnant the sector had been for decades. The license covers both TX-1 and the future TX-2 facility, currently in the design phase.
The project is part of the U.S. Department of Energy’s Advanced Reactor Demonstration Program, which covers up to 50% of X-energy’s costs for the demonstration of the Xe-100 reactor, including TX-1. The DOE has already authorized an additional $30 million in spending for the procurement of long-lead components needed to keep the overall schedule on track. Meanwhile, X-energy is conducting irradiation testing of TRISO-X fuel at Idaho National Laboratory, in a 13-month campaign at the Advanced Test Reactor aimed at qualifying the fuel for commercial use in the Xe-100.
X-energy began its TRISO fuel research on a pilot line at Oak Ridge National Laboratory in 2016. Nearly a decade later, the project is closing in on commercial production. TX-1 operations are expected to begin in 2027, with the first fuel deliveries destined for the Xe-100 plant planned in Texas, developed in partnership with Dow Chemical, at Seadrift. The State of Tennessee has meanwhile committed $11 million to support campus expansion — which, in the long run, could host enough production capacity to fuel around 55 Xe-100 reactors. If completed as planned, the campus would become one of the world’s largest commercial advanced nuclear fuel manufacturing hubs.
