Under Construction
TRISO-X Fuel Fabrication
First commercial-scale TRISO fuel fabrication facility in the United States, being built in Oak Ridge, Tennessee.
X-energyXe-100
In Development
80 MWe high-temperature gas-cooled reactor (HTGR) using TRISO fuel, deployable as single unit or in a four-pack configuration for 320 MWe.
Latest update Sep 18, 2026
01
Current status
DOE ARDP-funded HTGR advancing NRC licensing. The first deployment is the Amazon-backed Cascade Advanced Energy Facility with Energy Northwest in Washington (four units / 320 MWe, upsizable to 960 MWe), with Energy Northwest aiming to file a construction-permit application in the first half of 2027. For Dow's four-unit Seadrift / Long Mott project, the NRC issued a FONSI in May 2026 and set an uncontested construction-permit hearing for September 22, 2026 in Port Lavaca, with written comments open through October 6; staff are targeting a November 2026 final safety evaluation and a Q1 2027 construction-permit decision. Dow does not expect a final investment decision before 2028. The Xe-100 is in the UK Generic Design Assessment toward a 6 GW build-out with Centrica, and gigawatt-scale evaluations continue with Talen Energy (Pennsylvania) and LG&E and KU (Kentucky).
02
Specifications7
03
Upcoming milestones2
Announced next steps from X-energy that mention Xe-100.
2026
Finish TX-1 and begin licensed fuel manufacturing
TargetTX-1 interior buildout underway 2H 2026; full completion 1H 2028
X-energy's next major execution milestone is completing the TX-1 fuel-fabrication facility - vertical construction reached roughly 80% complete as of the Q2 2026 earnings call (August 13, 2026), up from 56% a quarter earlier, and on August 24, 2026 TRISO-X confirmed the facility has entered its next construction phase, starting interior buildout and auxiliary-building work as the main structure's vertical construction nears completion - and turning it into an operating commercial plant that can supply first-core loads for early Xe-100 deployments, still targeted for completion in the first half of 2028. A July 2026 $11M Tennessee state grant now backs a broader Oak Ridge campus build-out adding a second commercial facility (TX-2, expected to create 1,000+ jobs) and an R&D center (TX-L), scaling total planned capacity to fuel about 55 Xe-100 reactors.
2029
Advance Xe-100 through UK Generic Design Assessment
TargetGDA conclusion ~2029 (assessment started September 2026)
The GDA has formally started: on September 15, 2026 Centrica and X-energy said DESNZ had directed UK regulators to accept the Xe-100 into the Generic Design Assessment, following the June 2, 2026 submission. The Office for Nuclear Regulation, Environment Agency and Natural Resources Wales will administer a review expected to take about three years (concluding around 2029), with expanded UK-U.S. regulator collaboration meant to let NRC-reviewed design documentation and safety analyses transfer into the British assessment. Success is the gate on deploying up to 6 GW of Xe-100 capacity in Britain (10-20 stations), starting with a 12-unit, 960 MWe first project at the Hartlepool site named preferred location under the companies' September 2025 Joint Development Agreement. A decision on entry to the UK government's Advanced Nuclear Pipeline is expected imminently, and site studies plus planning and consenting work are already under way.
04
In the news8
X-energy finishes TX-1 fuel plant shell in Oak Ridge
TRISO-X, X-energy's fuel subsidiary, said on September 24 it completed vertical construction of the 214,000-square-foot TX-1 fuel fabrication plant in Oak Ridge, Tennessee. Work now moves to interior buildout, equipment installation, and supporting buildings under contractor Clark Construction. Once operating, TX-1 is expected to make about 700,000 TRISO pebbles a year, or 5 metric tons of uranium, enough for up to 11 Xe-100 reactors; commercial fuel making remains targeted after interior work, with operations still aimed at the first half of 2028.
UK accepts X-energy Xe-100 into design assessment
Centrica and X-energy said on September 15 that the Xe-100 high-temperature gas-cooled reactor has been accepted into the United Kingdom's Generic Design Assessment after the Department for Energy Security and Net Zero directed regulators to begin the review. The assessment will be run by the Office for Nuclear Regulation, the Environment Agency and Natural Resources Wales, is expected to take about three years, and is meant to draw on design documentation already reviewed by the U.S. Nuclear Regulatory Commission. The partners still want EDF and Centrica's Hartlepool site in north-east England as their first project ahead of a UK fleet of up to 6 GW, and said a decision on entry to the government's Advanced Nuclear Pipeline is expected imminently.
TRISO-X starts next construction phase for TX-1 fuel plant
TRISO-X, X-energy's fuel subsidiary, announced on August 24 that its TX-1 advanced nuclear fuel fabrication facility in Oak Ridge, Tennessee has moved into its next phase of construction, starting interior buildout and auxiliary-building work as vertical construction on the main structure nears completion. TX-1 is the first NRC-licensed commercial-scale HALEU fuel fabrication facility in the US and is designed to supply TRISO fuel pebbles for X-energy's Xe-100 reactors.
X-energy gets $1B more DOE backing as Q2 revenue jumps 154%
X-energy reported Q2 2026 revenue and grant income of $54.6 million, up 154% year over year, with $1.9 billion in total liquidity as of June 30. The same day, the Department of Energy formally notified X-energy that its Advanced Reactor Demonstration Program agreement will receive up to an additional $1 billion, raising DOE's total ARDP cost-share to as much as $2.115 billion across the Xe-100 reference plant, the TX-1 fuel facility, and the Dow Seadrift deployment.
X-energy and Centrus sign HALEU fuel supply agreement
X-energy and Centrus Energy announced a definitive agreement on August 6 for Centrus to enrich low-enriched and high-assay low-enriched uranium (HALEU) at its American Centrifuge Plant in Piketon, Ohio, supplying X-energy's TRISO-X fuel fabrication campus in Oak Ridge, Tennessee, with deliveries scheduled to begin in 2030. The phased deal is meant to secure a domestic HALEU supply chain for a portion of X-energy's 11.5 GW Xe-100 commercial reactor pipeline, with X-energy providing prepayments to help fund Centrus's enrichment capacity buildout.
X-energy, SGL Carbon to double nuclear-grade graphite output
X-energy and SGL Carbon announced a binding agreement on August 3 to double SGL's production capacity for NBG-18 medium-grain isotropic graphite, the specialized material used in the TRISO fuel pebbles and reflectors of X-energy's Xe-100 reactor. X-energy will invest up to $8 million in milestone payments toward new facilities and equipment at SGL's Chedde, France site, enough to supply graphite billets for up to 8 new Xe-100 reactors a year and double European NBG-18 capacity by 2030, building on a 10-year, over-$100 million supplier framework agreement signed in January 2026.
X-energy submits Xe-100 reactor for UK design assessment
X-energy on June 2 submitted its Xe-100 high-temperature gas-cooled reactor to enter the UK's Generic Design Assessment, the Office for Nuclear Regulation-led licensing pathway that evaluates a reactor's safety, security, and environmental case independent of a specific site. The submission, made with utility partner Centrica, supports plans to deploy up to 6 GW of new nuclear in Britain, with Hartlepool identified as the preferred first site for a 12-unit installation, and the assessment is expected to conclude by the end of 2029. The 80-MWe TRISO-fueled design is also advancing toward its first U.S. deployment with Dow in Texas.
X-energy files Xe-100 for UK Generic Design Assessment
X-energy on June 2 submitted its 80 MWe Xe-100 high-temperature gas-cooled reactor into the UK's Generic Design Assessment process, the regulatory gateway for new reactor designs in Britain. The filing is the first concrete step in X-energy and Centrica's joint plan to deploy up to 6 GW of new nuclear capacity in the UK and broadens the Xe-100 commercial slate alongside the Dow Seadrift project and the Amazon-backed Energy Northwest Cascade plant.
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