Main Building of X-energy's TRISO-X Nuclear Fuel Plant TX-1 Completed

TRISO-X, a wholly owned subsidiary of U.S. advanced nuclear developer X-energy, announced that the main building of its TX-1 advanced nuclear fuel manufacturing plant in Oak Ridge, Tennessee, has been officially completed. The building covers an area of 214,000 square feet (approximately 20,000 square meters), marking that the first commercial-scale advanced nuclear fuel manufacturing project of its kind in the United States has fully transitioned into the phase of interior mechanical and electrical fit-out, installation and commissioning of specialized fuel fabrication process equipment, and related supporting infrastructure construction.

According to capacity planning, once fully operational, the TX-1 plant will be capable of producing approximately 700,000 TRISO-X fuel pebbles per year, equivalent to an annual uranium equivalent output of about 5 tonnes, with the capability to continuously supply reload fuel for up to 11 Xe-100 high-temperature gas-cooled reactors. During the initial operational phase, the fuel produced by the plant will prioritize supporting the four-unit Xe-100 advanced small modular reactor (SMR) demonstration project that X-energy plans to deploy at Dow Inc.'s UCC Seadrift Operations site in Texas.

Previously, the U.S. Nuclear Regulatory Commission (NRC) officially issued TRISO-X a 40-year "Special Nuclear Material License" earlier this year, authorizing it to legally conduct commercial fuel manufacturing using High-Assay Low-Enriched Uranium (HALEU) within its first two commercial-scale plants, TX-1 and TX-2. In July of this year, TRISO-X also received an $11 million special development grant from the State of Tennessee to accelerate the expansion of the Oak Ridge fuel industrial park.

According to long-term planning, the entire Oak Ridge campus will consist of three core facilities: in addition to TX-1, whose main building has now been completed, the company also plans to build TX-2, a larger second-phase plant with higher automation and production efficiency, as well as TX-L, a dedicated laboratory facility focused on innovative new fuel design, irradiation testing, and continuous process improvement. The three will operate in coordination to build an independently controllable commercial-scale TRISO fuel manufacturing and R&D capability for the U.S. domestic advanced reactor supply chain.

The TRISO-X fuel pathway is the result of nearly a decade of technological development and qualification by X-energy and TRISO-X. Since 2016, the team has been conducting industrial-scale scale-up and optimization of the TRISO production process using the pilot line at Oak Ridge National Laboratory (ORNL). In 2025, TRISO-X fuel became the first commercial advanced nuclear fuel to enter the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) for irradiation testing, and the related tests are currently progressing steadily to fully obtain the safety licensing envelope data for the Xe-100 reactor.

TRISO fuel consists of micrometer-scale enriched uranium kernels surrounded by multiple layers of silicon carbide, pyrolytic carbon, and other ceramic high-temperature-resistant materials, providing an extremely robust solid-state safety self-containment barrier capable of tightly encapsulating fission products under extreme high temperatures. Its feedstock uses High-Assay Low-Enriched Uranium (HALEU) with uranium-235 enrichment between 5% and 20%. Compared with the 3.5% to 5% low-enriched uranium commonly used in currently operating commercial light-water reactors, it can provide higher burnup depth and longer refueling cycles, and is regarded as the core energy carrier for fourth-generation advanced high-temperature gas-cooled reactors and microreactors.