In Development
Natrium
Sodium-cooled fast reactor with integrated molten salt energy storage, enabling flexible output from 345 MWe to 500 MWe peak.
TerraPower is a nuclear innovation company founded by Bill Gates with two business lines: the Natrium sodium fast reactor with integrated molten-salt energy storage, and TerraPower Isotopes, a medical-isotope business producing actinium-225 for targeted cancer therapies.
Latest update Oct 7, 2026
01
Overview
In March 2026 the NRC issued Kemmerer Unit 1 the first construction permit for a commercial-scale advanced nuclear plant in the U.S., and on April 23, 2026 TerraPower and then-contractor Bechtel officially began plant construction in Wyoming, a build expected to mobilize roughly 1,600 workers; on July 21, 2026 TerraPower became the first advanced-reactor developer accepted into the Institute of Nuclear Power Operations. A Bechtel WARN notice signed September 13, 2026 and reported September 17 says the two companies could not agree terms for the next phase of the Natrium Demonstration Project and have decided to move forward separately, with Bechtel planning about 200 Reston layoffs from around November 16; TerraPower has not named a replacement contractor for Kemmerer Unit 1. In January 2026 TerraPower signed a landmark agreement with Meta to develop up to eight Natrium plants in the U.S., marking a shift from a single demonstration toward a commercial fleet, and on August 14, 2026 it deepened its Korean industrial supply chain with a preliminary joint-business agreement with SK Innovation for South Korea's first commercial Natrium plant, selection of Hyundai Engineering & Construction as EPC contractor for up to eight future Natrium reactors, and a reactor-vessel manufacturing contract with Doosan Enerbility. In August 2026 it named George Wilson, previously SVP of Regulatory Affairs, as its first Chief Nuclear Officer to oversee nuclear safety, licensing, and regulatory strategy, and on August 31 it awarded 12 additional supplier contracts for Kemmerer Unit 1 and an on-site sodium test and fill facility. CEO Chris Levesque told Reuters on September 7, 2026 that Natrium could generate UK electricity by 2034, TerraPower's first market outside the United States, and has said the company still plans to announce a second Natrium project - this one for an unnamed AI data-center customer - before the end of 2026, with construction targeted for 2027. The core reactor business remains pre-revenue, but Natrium has moved from development into full project execution under DOE's ARDP cost-share program, while TerraPower Isotopes already sells actinium-225 commercially to pharmaceutical partners and is building a $450 million second production facility in Philadelphia.
patch.comUpdated Sep 18, 2026
Analysis · 6 min read · Jul 12, 2026The long view on TerraPower: strategy, technology and what to watch02
What's next9
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.
Mar 2028
Submit Kemmerer Unit 1 operating license application
File the Part 50 operating license application for Kemmerer Unit 1 with the NRC, the second step of the two-step construction-permit-then-operating-license process, which TerraPower has said it is targeting for March 2028 - a milestone the company has been preparing for in part through its July 2026 admission to the Institute of Nuclear Power Operations.
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.
2029
Bring Bellwether Laboratory (Philadelphia) online
Complete construction of the $450M, 250,000-square-foot Bellwether Laboratory in Philadelphia's Bellwether District (groundbreaking May 6, 2026) and begin cGMP actinium-225 production there, expanding TerraPower Isotopes' global Ac-225 capacity twentyfold alongside its existing Everett, Washington site. Not yet online as of September 18, 2026; TerraPower's isotopes page still describes the Philadelphia plant as under construction with a twentyfold capacity increase, and no delay to the 2029 production-start target has been reported.
2031
Execute Kemmerer Unit 1 construction
TargetConstruction complete ~Feb 2031
With construction underway and a workforce mobilizing toward ~1,600 (Kemmerer is advancing temporary workforce-housing zoning to accommodate the ramp), TerraPower's central execution challenge is building Kemmerer Unit 1 on schedule. Early work is focused on the non-nuclear energy island under the January 2025 Wyoming state construction permit, with the nuclear island to follow under the March 2026 NRC construction permit's operating-license phase; project owner US SFR Owner LLC has told the NRC it is targeting fuel loading around 2030 and expects to complete construction by February 2031, ahead of commercial operation targeted in 2031. The build now has to absorb a contractor change: a Bechtel WARN notice signed September 13, 2026 says the two companies could not agree terms for the project's next phase and have decided to move forward separately, cutting about 200 Bechtel positions in Reston from around November 16.
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.
03
Latest 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.
04
Products3
In DevelopmentMolten Salt Energy Storage
Integrated thermal energy storage system using molten salt to decouple reactor output from grid delivery, enabling peak power output.
- Active
TerraPower Isotopes (Actinium-225)
Medical-isotope business producing actinium-225 (Ac-225), a rare alpha-particle-emitting isotope used in targeted radiotherapeutics for cancers including prostate, breast, colon, and neuroendocrine cancers, melanoma, and lymphoma.
05
Key metrics
- Employees
- ~1,000
- Est. annual revenue
- Pre-revenue
Re-verified Sept 18, 2026: the core Natrium business has not begun electricity sales; TerraPower Isotopes sells actinium-225 commercially but TerraPower does not disclose isotope revenue.
- Kemmerer Unit 1 Status
- Under construction
(started Apr. 23, 2026); energy island proceeding under the January 2025 Wyoming state permit while the nuclear island follows under the March 2026 NRC construction permit. A Bechtel WARN notice signed Sept. 13, 2026 says the two companies could not agree terms for the next phase and will move forward separately; TerraPower has not named a replacement contractor as of Sept. 18, 2026. TerraPower's Aug 31, 2026 vendor announcement still says the plant is expected to be completed in 2030; project owner US SFR Owner LLC has separately told the NRC it expects construction complete ~Feb 2031, with fuel loading around 2030 and commercial operation 2031
06
Operations & revenue
Operating status
Pre-revenue
Pre-revenue, but no longer just at the concept stage. Kemmerer Unit 1 received an NRC construction permit in March 2026 and entered full construction with contractor Bechtel on April 23, 2026, mobilizing toward roughly 1,600 workers at peak. A Bechtel WARN notice signed September 13, 2026 says the two companies could not agree terms for the next phase of the Natrium Demonstration Project and have decided to move forward separately, with Bechtel planning about 200 Reston layoffs from around November 16; as of September 18, 2026 TerraPower has not named a replacement contractor or said whether the Kemmerer schedule moves. Because Natrium is being built under a two-step Part 50 process, early construction work is concentrated on the non-nuclear energy-storage island (under a January 2025 Wyoming state permit) while the reactor (nuclear) island follows under the separate NRC operating-license phase. TerraPower's August 31, 2026 vendor announcement still says the plant is expected to be completed in 2030; project owner US SFR Owner LLC has told the NRC it expects to complete construction by February 2031, with commercial operation targeted in 2031. A January 2026 agreement with Meta for up to eight Natrium plants and 2026 commercialization agreements with HD Hyundai, HDEC, SK Innovation, and Doosan Enerbility position TerraPower among the most commercially advanced U.S. advanced-reactor developers. In August 2026 it named George Wilson its first Chief Nuclear Officer, and on September 7 CEO Chris Levesque told Reuters that first UK Natrium electricity in 2034 is very possible. A second U.S. plant for an unnamed AI data-center customer has not yet been announced as of September 18, 2026.
Pipeline & contracts
$2B+ from DOE's Advanced Reactor Demonstration Program to build the Natrium demonstration plant.
Private Investment & Partnerships
Significant investment from Bill Gates, SK Group, and venture partners funding reactor development and demonstration.
Commercial Reactor Deployment (Meta Agreement)
January 2026 agreement with Meta to develop up to eight Natrium plants (up to 2.8 GW baseload, 4 GW peak with storage); Meta funds early development of two units and holds rights to six more - TerraPower's path to commercial revenue beyond the Kemmerer demonstration.
TerraPower Isotopes (Actinium-225 Sales)
TerraPower's nearer-term commercial line: producing and selling actinium-225, a medical isotope used in targeted alpha-particle cancer therapies, at commercial scale via weekly production runs since October 2024, under supply agreements with pharmaceutical partners including AtomVie Global Radiopharma, Ratio Therapeutics, and Clarity Pharmaceuticals. A $450M Philadelphia facility (breaking ground May 2026, production from 2029) is intended to expand capacity twentyfold, and a June 2026 expanded collaboration with Belgian producer PanTera adds a new Ac-225 production line at IRE's Fleurus site.
07
Timeline23
2026
Bechtel steps back from Natrium's next construction phase
In a Worker Adjustment and Retraining Notification Act notice signed September 13, 2026 and reported on September 17, Bechtel Power Corporation told Virginia workforce officials it will cut about 200 positions at its Reston headquarters because it and TerraPower could not agree terms for the next phase of the Natrium Demonstration Project and have decided to move forward separately. The layoffs would begin on or about November 16, 2026, though Bechtel said it is trying to place affected employees on other assignments. Bechtel had been TerraPower's engineering, procurement and construction contractor since 2020 and began field execution at Kemmerer Unit 1 on April 23, 2026.
CEO targets first UK Natrium electricity in 2034
On September 7, 2026 CEO Chris Levesque told Reuters that Natrium reactors could begin generating electricity in Britain by 2034, making the UK TerraPower's first market outside the United States. He said progress on the Wyoming plant, due to be completed in 2031, showed that 2034 UK power is very possible, and that electricity would cost under 100 pounds per megawatt hour. TerraPower has not chosen a UK site; its British subsidiary is likely to be based in Liverpool, near the nuclear regulator.
Awards 12 supplier contracts for Kemmerer Unit 1 and sodium test facility
On August 31, 2026 TerraPower announced 12 additional supplier awards supporting construction of Kemmerer Unit 1 and completion of the first-of-a-kind on-site sodium test and fill facility. Vendors include Merrick (pin-removal cell and sodium cover-gas monitoring skids), Mirion (plant cyber system), BWXT Canada (control rod drives), Teledyne Brown, Marmen, Thermal Engineering International, Jensen Hughes, Boston Government Services, James Fisher Technologies, KROHNE Nuclear, and Valserve.
Names George Wilson first Chief Nuclear Officer
In August 2026 TerraPower appointed George Wilson as its first Chief Nuclear Officer. Wilson, who joined in March 2021 and built the Regulatory Affairs group that secured the NRC's first modern commercial fast-reactor construction permit, keeps his Senior Vice President of Regulatory Affairs role and now also oversees nuclear safety, licensing, and regulatory strategy. He is a former NRC office director and TVA Watts Bar construction and operations manager.
New ORNL analytical lab speeds Th-229 supply for Ac-225 production
On August 21, 2026 the Department of Energy's Oak Ridge Office of Environmental Management and contractor Isotek Systems open a new analytical laboratory (Building 2026) at Oak Ridge National Laboratory that speeds cleanup of ORNL's uranium-233 inventory and accelerates delivery of thorium-229 to TerraPower Isotopes, which is contracted to extract actinium-225 from that Th-229 using a radioisotope decay-based technique. The faster analysis shortens shipment delays that previously required sending samples elsewhere for testing, supporting TerraPower Isotopes' commercial-scale Ac-225 supply to pharmaceutical partners.
SK Innovation JV agreement and HDEC named EPC contractor for Korea fleet
On August 14, 2026 TerraPower signed a preliminary global joint-business agreement with SK Innovation - covering South Korea's first commercial Natrium plant and potential overseas projects - and selected Hyundai Engineering & Construction (HDEC) as the engineering, procurement and construction contractor for up to eight future Natrium reactors, with completion, price and performance guarantees intended to support conventional commercial financing. The agreements were signed in Seoul with TerraPower chairman Bill Gates, 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 Natrium's reactor vessel and internal structures, deepening the Korean industrial supply chain first established in TerraPower's May 2026 HD Hyundai agreements.
TerraPower Isotopes expands PanTera collaboration
On June 2, 2026 TerraPower Isotopes and Belgian radioisotope producer PanTera expand their existing actinium-225 collaboration: Belgium's Institut des Radioeléments (IRE) in Fleurus will host and operate a new Ac-225 production line for PanTera, with TerraPower Isotopes supplying additional starting material, while PanTera separately builds a photonuclear production plant in Mol. The new IRE line is expected to become operational within about 18 months.
Groundbreaking on Bellwether Laboratory in Philadelphia
On May 6, 2026 TerraPower Isotopes breaks ground on the 250,000-square-foot Bellwether Laboratory in Philadelphia's Bellwether District, its flagship actinium-225 manufacturing facility; cGMP production is scheduled to begin in 2029.
2026
TerraPower Isotopes announces $450M Philadelphia cGMP facility
On March 17, 2026 TerraPower Isotopes unveils plans to invest $450 million in a cGMP actinium-225 manufacturing facility in Philadelphia's Bellwether District, which together with capacity expansion at its existing Everett, Washington site is intended to increase global Ac-225 production capacity twentyfold.
First advanced reactor company to join INPO
On July 21, 2026 TerraPower is 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 move aligns TerraPower with INPO's operational-excellence and safety standards as it builds toward submitting a Kemmerer Unit 1 operating license application by 2028.
Natrium enters UK Generic Design Assessment
On June 16, 2026 TerraPower's Natrium reactor formally enters the UK's Generic Design Assessment - the Office for Nuclear Regulation-led licensing process that evaluates a reactor's safety, security and environmental case independent of a specific site - and the company launches a UK subsidiary, TerraPower UK Ltd, to pursue British deployment. It is TerraPower's first regulatory step toward building Natrium plants in the UK.
Korean commercialization agreements with HD Hyundai and HDEC
On May 20, 2026 TerraPower signs a set of Natrium commercialization agreements with HD Hyundai and Hyundai Engineering & Construction (HDEC): a supply framework agreement naming HD Hyundai Heavy Industries a preferred manufacturer for components of the Natrium Reactor Enclosure System, and a tripartite strategic agreement/MOU to collaborate on design, manufacturing, supply chain, construction, commercialization, and delivery of a fleet of Natrium reactor-and-storage plants. HD Hyundai had already invested $30M in TerraPower in 2022.
NRC permit issued and full Natrium construction begins
The NRC issues the first construction permit for a commercial-scale advanced nuclear plant in the U.S. on March 4, 2026, and TerraPower together with contractor Bechtel officially begins construction of Kemmerer Unit 1 on April 23, 2026, a build expected to mobilize roughly 1,600 workers.
Meta agreement for up to eight Natrium plants
In January 2026 TerraPower signs a landmark agreement with Meta to develop up to eight Natrium reactor-and-storage plants in the U.S. - up to 2.8 GW of baseload power, boostable to 4 GW with the molten-salt storage. Meta funds early development of two units and holds rights to six more, with first units targeted as early as 2032.
2025
$650M growth round led by NVIDIA's NVentures
TerraPower closes a $650 million private funding round including NVIDIA (via its NVentures venture arm, marking Nvidia's first energy investment), returning backer Bill Gates, and HD Hyundai, funding continued Natrium development and the TerraPower Isotopes program.
2024
TerraPower Isotopes reaches market-scale Ac-225 production
TerraPower Isotopes announces it is producing actinium-225 at commercial scale via weekly production runs, supplying the global pharmaceutical industry for radiopharmaceutical development, including drugs in human clinical trials.
Site work and project preparation advance
TerraPower advances early project work in Kemmerer ahead of receiving the NRC construction permit for the first Natrium plant.
2022
2020
2019
2015
2010
2008
08
Funding
$4.5Bdisclosed across 4 rounds with a stated amount
Cumulative disclosed raise · dated rounds
RoundAmountInvestors
Founder & early investors
2008–2018
Bill Gates, Khosla Ventures, venture partners
DOE ARDP cost-share
2020
U.S. Department of Energy
Series B (two closes)
2022
$830M ($750M in Aug. 2022 + $80M add-on in Nov. 2022)
SK Group (SK Inc./SK Innovation), Bill Gates, ArcelorMittal (XCarb Innovation Fund), Korea Shipbuilding and Offshore Engineering (HD Hyundai), others
Growth round
2025-06
NVIDIA (via NVentures), Bill Gates, HD Hyundai
