In Development
Molten Salt Energy Storage
Integrated thermal energy storage system using molten salt to decouple reactor output from grid delivery, enabling peak power output.
TerraPowerNatrium
In Development
Sodium-cooled fast reactor with integrated molten salt energy storage, enabling flexible output from 345 MWe to 500 MWe peak.
Latest update Sep 18, 2026
01
Current status
Demonstration plant (Kemmerer Unit 1) under construction in Wyoming - NRC construction permit issued March 2026, construction started April 2026 with then-contractor Bechtel. A Bechtel WARN notice signed September 13, 2026 says the two companies could not agree terms for the next phase and have decided to move forward separately; TerraPower has not named a replacement contractor as of September 18, 2026. Construction completion is targeted by ~February 2031 and commercial operation in the early 2030s. A January 2026 Meta agreement covers up to eight additional Natrium plants; May and August 2026 Korean agreements with HD Hyundai, HDEC, SK Innovation, and Doosan Enerbility support component manufacturing and EPC delivery for the commercial fleet; and CEO Chris Levesque told Reuters on September 7, 2026 that first UK Natrium electricity in 2034 is very possible. A second U.S. plant for an unnamed AI data-center customer is still planned to be announced before year-end 2026, with construction targeted for 2027.
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Specifications6
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Upcoming milestones6
Announced next steps from TerraPower that mention Natrium.
By end of 2026
Set out how Kemmerer Unit 1 gets built without Bechtel
Bechtel, TerraPower's engineering, procurement and construction contractor since 2020, told Virginia workforce officials in a WARN notice signed September 13, 2026 that the two sides failed to agree on the next phase of the Natrium Demonstration Project and have decided to move forward separately, scaling down its Reston support organization by about 200 roles from on or about November 16. Neither company has published a joint statement, named a replacement contractor or self-perform plan, or said whether the Kemmerer schedule (construction complete around February 2031) moves as a result. TerraPower separately selected Hyundai Engineering & Construction in August 2026 as EPC contractor for up to eight future Natrium reactors, but that arrangement covers the commercial fleet rather than the Wyoming demonstration unit.
By end of 2026
Announce second Natrium plant, for an AI data center customer
CEO Chris Levesque said TerraPower plans to announce its next Natrium project before the end of 2026, this time for an unnamed AI data center customer rather than Kemmerer's utility-scale grid role, putting the company on track to break ground on its second plant in 2027. As of September 18, 2026 the customer, site, capacity, and commercial terms remain undisclosed - no announcement has been made since the August 18 Bloomberg interview. The disclosure follows TerraPower's August 14, 2026 agreements with Hyundai E&C and SK Innovation to help standardize and scale Natrium construction for a commercial fleet.
Late 2020s
Secure HALEU fuel supply
Natrium operation depends on securing adequate HALEU fuel through TerraPower's partnerships with Centrus, Framatome, GNF-A, and ASP Isotopes, plus completing supporting fuel-fabrication and sodium test-and-fill infrastructure under the ARDP program. ASP Isotopes' definitive agreements with TerraPower (a loan for its planned South Africa enrichment facility plus a long-term supply contract for up to 150 metric tons of HALEU over the 2028-2037 period) remain on track toward supply beginning in 2028, alongside TerraPower's DOE HALEU Availability Program allocation.
Early 2030s
First sodium reactor criticality
Targeting initial criticality of the Natrium reactor at the Kemmerer plant, marking the first sodium-cooled fast reactor to operate in the U.S. in decades, following fuel loading targeted around 2030 and ahead of construction completion (~February 2031) and commercial operation (2031). Not yet achieved as of September 2026; Natrium is not part of the separate federal push (a 2025 executive order and DOE Reactor Pilot Program) for other advanced-reactor developers to reach criticality by July 2026, since Kemmerer Unit 1 is following the NRC's standard two-step Part 50 licensing path instead.
2032
Begin commercial Natrium fleet under Meta agreement
Move the January 2026 Meta agreement for up to eight Natrium plants from early development into deployment, with the first commercial units targeted to come online as early as 2032. TerraPower's May 2026 commercialization agreements with HD Hyundai and HDEC are intended to build out the component-manufacturing and EPC supply chain needed to deliver the fleet at scale. Cheyenne, Wyoming - home to Meta's large Project Cosmo data center campus - has emerged as a leading candidate site for the initial dual-reactor unit, though TerraPower and Meta had not formally confirmed a site as of mid-2026.
2034
Advance Natrium through UK Generic Design Assessment
Having submitted its GDA application in October 2025, received formal acceptance from the UK Department for Energy Security and Net Zero in February 2026, and started Step 1 of the three-step regulatory review on June 5, 2026 through subsidiary TerraPower UK Ltd, progress the multi-year process toward a first UK Natrium plant. CEO Chris Levesque told Reuters on September 7, 2026 that UK electricity from Natrium in 2034 is very possible, citing Wyoming construction progress toward a 2031 completion, and that power would cost under 100 pounds per megawatt hour. No UK site has been chosen; the British subsidiary is likely to be based in Liverpool.
04
In the news8
Bechtel walks away from Natrium's next construction phase
Bechtel Power Corporation has told Virginia workforce officials it will cut about 200 positions at its Reston headquarters after it and TerraPower failed to agree terms for the next phase of the Natrium Demonstration Project and, in the words of the filing, decided to move forward separately. The Worker Adjustment and Retraining Notification Act notice was signed on September 13 by Bechtel's Natrium project director, Suchit Chopra, and says the layoffs would begin on or about November 16, though Bechtel is trying to place affected staff on other assignments. Bechtel has been TerraPower's engineering, procurement and construction contractor since 2020 and started field construction at Kemmerer Unit 1 in Wyoming in April 2026, the first utility-scale advanced reactor build in the United States.
TerraPower targets first UK Natrium power in 2034
TerraPower CEO Chris Levesque told Reuters on September 7, 2026 that Natrium reactors could begin generating electricity in Britain by 2034, making the UK the company's first market outside the United States. The sodium-cooled design, already under construction in Wyoming and in the UK Generic Design Assessment, produces 345 MW of baseload power and can boost to 500 MW for more than five hours using molten-salt storage. Levesque said power would cost under 100 pounds per megawatt hour; TerraPower has not chosen a UK site but said its British subsidiary is likely to be based in Liverpool.
TerraPower awards 12 supplier contracts for Kemmerer Unit 1
TerraPower said on August 31, 2026 it awarded 12 additional vendor contracts for Kemmerer Unit 1, covering the Natrium plant and an on-site sodium test and fill facility. The awards include work for Merrick (two contracts), Mirion, BWXT Canada, Teledyne Brown, Marmen, Thermal Engineering International, Jensen Hughes, Boston Government Services, James Fisher Technologies, KROHNE Nuclear, and Valserve. The round deepens the U.S. supply chain as construction of the first utility-scale advanced reactor continues in Wyoming.
TerraPower taps Hyundai E&C to build up to eight Natrium reactors
TerraPower, HD Hyundai and Hyundai E&C signed a framework agreement naming Hyundai E&C as engineering, procurement and construction partner for up to eight additional Natrium units, with completion, price and performance guarantees. HD Hyundai will manufacture major equipment while TerraPower supplies the reactor technology. The joint release went out in mid-August and Korean coverage broke on August 18 after TerraPower CEO Chris Levesque visited Hyundai E&C headquarters in Seoul.
TerraPower plans second Natrium plant for an AI data center
TerraPower CEO Chris Levesque said the Bill Gates backed nuclear company plans to announce its next Natrium advanced reactor project before the end of 2026, this time for an AI data center customer it declined to name, putting the company on track to break ground on its second plant in 2027. The disclosure follows TerraPower's August 14 agreements with Hyundai E&C and SK Innovation to help standardize and scale Natrium construction.
TerraPower signs Korean reactor deals with Hyundai, SK, Doosan
TerraPower signed a preliminary global joint-business agreement with SK Innovation and selected Hyundai Engineering & Construction as the EPC contractor for up to eight future Natrium reactors, in agreements finalized August 14 during meetings in Seoul with SK Group chairman Chey Tae-won and South Korea's Trade, Industry and Energy Minister Kim Jung-kwan. South Korea's Doosan Enerbility separately won a TerraPower contract to manufacture the Natrium reactor vessel and internal structures, deepening the Korean industrial supply chain behind TerraPower's push to commercialize its sodium-cooled reactor design beyond its Kemmerer, Wyoming plant.
TerraPower becomes first advanced reactor company to join INPO
TerraPower said on July 21 it has been accepted into the Institute of Nuclear Power Operations (INPO), becoming the first advanced-reactor developer admitted to the industry safety group whose membership has historically been limited to operators of existing commercial nuclear plants. The company said INPO membership aligns it with operational-excellence and safety standards as it builds Kemmerer Unit 1, its Natrium demonstration plant in Wyoming, toward an operating license application by 2028. INPO promotes safety, reliability and continuous learning across the US commercial nuclear fleet.
TerraPower enters UK regulatory review, opens UK subsidiary
TerraPower said on June 16 that its 345-MWe Natrium sodium-cooled fast reactor has formally entered the UK's Generic Design Assessment, the Office for Nuclear Regulation-led licensing process that vets a reactor's safety, security and environmental case independent of a site. The Bill Gates-founded company also launched a UK subsidiary, TerraPower UK Ltd, to pursue British deployment. The move follows the April 23 start of construction on TerraPower's flagship Kemmerer Unit 1 in Wyoming, the first U.S. utility-scale advanced reactor build, which is targeted for completion around 2030.
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