The goal posts are in sight for TerraPower which is developing a 345 MW sodium cooled advanced reactor at the site of a formere coal-fired power plant in Kemmerer, WY. At TerraPower, based on Bellevue, WA, Executive Vice President and COO Eric Williams said in a video interview, âThe commercial operation delivery date, power on the grid, is 2031.â
To get there, the firm must get a construction license from the U.S. Nuclear Regulatory Commission (NRC), which is expected in the first few months of 2026.
Once the license is in hand, the firm plans to pour its first nuclear-related concrete at the Kemmerer, WY, site by 2027. The firm has a 36-month timeline to get ready for loading fuel and that milestone is targeted for 2030.
During this three year period, the firm prepare and submit an application to the NRC for its operating license with a target date of 2028. The loading of fuel in 2030 kicks off a period of commissioning the reactor to enter revenue service by 2031. (Image: Google Gemini generated)
Completion of Environmental Reviews
On October 20, 2025, the firm achieved a major milestone with the completion of its final environmental impact statement (EIS). While the 345 MW sodium-cooled advanced reactor is intended to replace a coal-fired power plant, Williams said âwe completely characterized it going through the entire site development process.â
He added, âWe did a full seismic hazard analysis.â
Getting federal approval for the EIS wasnât the only regulatory hurdle the firm had to face. In terms of dealing with the State of Wyoming, âthere were something like 55 permits we needed,â Williams said.
One of the issues that didnât delay state approvals is legislation passed earlier this year that prohibited importing spent nuclear fuel into the state. Because TerraPower is only generating spent fuel on-site, and not bringing it in from elsewhere, TerraPower is exempt from these legislationâs requirements, which forced Radiant, a developer of a transportable microreactor, to abandon its plans to build a nuclear reactor refueling depot just north of Casper, WY.
Nuclear Reactor HALEU Fuel Strategy
Terra Power is also circumventing the national shortage of high assay, low-enriched nuclear fuel (HALEU) that is affecting other developers in the U.S. of advanced nuclear reactors. It is pursuing a program of self-reliance when it comes to HALEU.
TerraPower has inked a 10-year contract for uranium enrichment with ASP, a South African company. The firm has a U.S. presence and is listed on NASDAQ (NASDAQ:ASPI). The enrichment plant that will supply the HALEU to TerraPower is in Pretoria, South Africa.
Williams said the advantage of the ASP contract is, âthey will use an enrichment facility in South Africa that will give us the highly enriched uranium.â
To raise funds for its U.S. expansion and operations on November 12, 2025, ASP announced plans for an initial public offering via a wholly-owned subsidiary, Quantum Leap Energy LLC. The timing of the proposed initial public offering remains subject to the completion of the SEC review process as well as market and other conditions.
The initial core supply agreement is intended to provide the first fuel cores for the initial loading of TerraPowerâs Natrium project in Wyoming during the 2027/2028 timeframe. The long-term supply agreement is for up to 150 metric tons of HALEU, commencing in 2028 and continuing through to the end of 2037. Once the enriched uranium, at 19.5% U235, is ready, it will be sent to the Framatome nuclear fuel plant located in Richland, WA.
On November 5, 2025, Framatome and TerraPower achieved a key milestone in uranium metallization for advanced reactor fuel commercialization, producing successful elements of uranium metal. These metallic uranium âpucksâ represent a key component in the fuel supply chain for TerraPowerâs Natrium reactor.
Production of HALEU metal is a crucial part of the fuel fabrication process, which allows uranium to be transformed into a metallic feedstock that is used to fabricate fuel elements and assemblies for advanced reactors.
Once the metal fuel is ready, it is shipped from Framatomeâs plant in Richland, WA, to Global Nuclear Fuels in Wilmington, NC, to be fabricated into the fuel assemblies that will go into the Natrium reactor that will produce its heat and power through the nuclear fission process.
In addition to the contract for HALEU with ASP, TerraPower is also participating in the U.S. Department of Energyâs HALEU Availability Program.
The DOE HALEU program will supply developers of advanced reactors, including TerraPower, with enriched uranium from several sources, including fuel down blended from highly enriched uranium (HEU), taken from DOEâs weapons complex facilities, as well as newly enriched uranium delivered by four firms now under contract with DOE.
The HALEU Availability Program is intended to spur demand for additional HALEU production and private investment in the nationâs nuclear fuel supply infrastructure, ultimately removing the federal governmentâs initial role as a supplier.
Plans for Expansion Beyond Wyoming
In addition to completing its first-of-a-kind plant at the Kemmerer, WY, site, TerraPower is planning to enter the nuclear power market in the U.K.
âWe think there is excellent market potential there,â Williams said.
âThe Natrium plant provides energy storage, with its molten salt storage system, thatâs really attractive for balancing swings in the electric power grid.â
To pursue the U.K. market, on October 28, 2025, TerraPower announced the official submission of the Natrium reactor and energy storage system in the Generic Design Assessment (GDA) process which is managed by the U.K. governmentâs Office of Nuclear Regulation. The GDA process is similar to the NRCâs licensing requirements. This is the companyâs first regulatory step to deploying the Natrium reactor technology in an international market.
TerraPower and KBR (NYSE:KBR) announced on March 13, 2025, their joint efforts to identify sites for the Natrium reactor in the U.K. Under the arrangement, TerraPower will lead efforts related to engineering, research and development, supply chain, and regulatory activities. KBR may provide Engineering, Procurement, and Construction Management (EPC) services, including design, commissioning, and financial leadership.
Scouting for U.S. Customers
Williams said that while no firm commitments have been made, the firm is scouting sites in U.S. utility markets in Utah and Kansas. Memorandums of Understanding (MOU), which are non-binding agreements, have been established with state governments in these states and with private sector firms in these states.
About the TerraPower Natrium Reactor.
Unlike todayâs light water reactors (LWR), the Natrium reactor is a 345 MW sodium fast reactor coupled with TerraPowerâs innovation, which is a molten salt integrated energy storage system. The molten salt is wholly contained in its own system separate from the sodium system that cools the reactor.
Natrium reactors are not pressurized like existing light water reactors. It uses sodium, instead of water, as a coolant. The reactor operates at a temperatures far greater than 350 degrees Celsius (the equivalent of 662 degrees Fahrenheit) and far below the boiling point of sodium of 1,621 Fahrenheit.
TerraPowerâs design capitalizes on natural forces, such as gravity and thermal convection, enabling passive cooling, which reduces safety-related costs compared to conventional reactors.
The heat from the reactor drives the steam system that generates electricity through a turbine. Also, it stores the heat for times when peak electricity demand requires a âjet assistedâ boost in power from 345 MW to over 500 MW for up to 5.5 hours. Examples include times when renewable energy, such as wind or solar, are not available. The storage system allows the plant to âload followâ demand on the grid without having to adjust the power output of the reactor itself. [Image: TerraPower]
Additionally, its design allows for separation and âdecouplingâ of the molten salt energy storage and nuclear island, ensuring these systems are completely separated from the nuclear portion of the plant. The molten salt pool serves as a heat transfer medium to run the steam system and turbine to generate electricity.
This design permits non-nuclear project teams to operate significant plant operations, like the steam turbines and salt tanks, outside of the nuclear control area. This is safer and reduces costs.
Leveraging the Advantage of Molten Salt Energy Storage
Williams said that unlike light water plants, the Natrium design does not load follow on the grid based on changing power production of heat by the reactor itself.
âThe molten salt bath, a storage system, is a key feature, serving as a heat reservoir. This allows the plant to hold heat from the nuclear side and quickly generate more steam to boost electricity output, a âjet assist,â when demand from the grid is high, without immediately changing the reactor power level.â
âThis allows the Natrium plant to integrate with renewables on the grid,â Williams said.
âThe molten salt is a great fluid for storing energy. It loves to hold on to heat. And so, you can move the heat from the nuclear side of the plant to your energy storage side of the plant wherever your heat user is, e.g., for some industrial process. And then, once you need more electricity on the grid, you simply dial up the flow of the salt so that you generate more steam. Itâs still a steam Rankine cycle and a steam turbine just like any other power plant. It just has a molten salt side thatâs generating the steam.â
Natrium by the Numbers
⢠Reactor thermal output: 840 Mwt
⢠Power output â nuclear island: 345 Mwe
⢠Power output â energy storage system: 100-500 MWE for up to 5.5 hours
⢠Heat output from the reactor: 930 Fahrenheit
⢠Primary operating pressure: atmospheric
⢠Time to build one: 36 months from first concrete pour to fuel load
⢠Construction cost efficiencies: 50% less concrete, steel, and labor compared to a similar size LWR.
⢠Operational lifespan: 80 years
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