The U.S. Nuclear Regulatory Commission (NRC) has issued a construction permit for Dow’s proposed 320-megawatt advanced nuclear project in Texas, clearing a major regulatory milestone for a four-reactor facility designed to supply electricity and industrial steam to the company’s Seadrift manufacturing complex.
Dow and X-energy announced the approval on November 9, 2026, for the proposed Long Mott Generating Station at Dow’s UCC Seadrift Operations site in Calhoun County. The facility would use four Xe-100 high-temperature gas-cooled reactors, each designed to produce 80 MW of electricity and 200 MW of thermal energy.
Together, the four reactors would provide 320 MW of electrical capacity and 800 MW of thermal capacity. The companies intend to use the output to replace existing energy and steam assets at the chemical manufacturing site as those facilities approach the end of their operating lives.
The construction permit is a significant regulatory achievement, but it does not mean Dow has committed to building the plant. The company still needs to complete engineering and design work, assess the project’s commercial competitiveness and affordability, and secure the necessary investment approvals before full-scale nuclear construction can begin.
Four Xe-100 reactors would supply industrial power and heat
Long Mott would use X-energy’s Xe-100 reactor technology, a high-temperature gas-cooled design that uses helium as a coolant and graphite as a moderator. The reactors would use TRISO-coated particle fuel, which incorporates multiple protective layers around the nuclear fuel.
Each Xe-100 module is designed to produce 80 MWe of electricity and 200 MWt of thermal energy. Across four units, the proposed facility would provide 320 MWe and 800 MWt.
The distinction matters because the 800 MWt figure represents thermal output, not additional electricity. The project is designed to provide both electricity and high-temperature steam for Dow’s industrial operations, making it different from a conventional nuclear power station focused primarily on electricity sales to the grid.
The proposed industrial integration is central to the project’s purpose. Chemical manufacturing requires dependable energy and process heat, and the companies intend to use nuclear generation to replace existing energy and steam assets at Seadrift.
However, Dow and X-energy have not publicly detailed the precise volumes of electricity and steam the reactors would supply, how the output would be allocated among industrial processes or whether any surplus electricity would be available for sale to the grid.
NRC approval completes construction permit review
Long Mott Energy LLC, Dow’s wholly owned subsidiary and the permit applicant, submitted its construction permit application to the NRC on March 31, 2025. The regulator docketed the application in May 2025 and reviewed the proposed facility under its commercial nuclear licensing process.
The NRC completed its safety and environmental reviews before issuing the construction permit. Its environmental review resulted in an Environmental Assessment and Finding of No Significant Impact in May 2026, rather than a full environmental impact statement.
The permit authorizes construction in accordance with the approved design and is a major milestone for advanced nuclear deployment at an operating industrial site. The companies describe Long Mott as the first advanced nuclear facility approved for construction at a U.S. industrial site, the first NRC construction permit approval for a high-temperature gas-cooled reactor in nearly 60 years, and the first for a pebble-bed high-temperature gas-cooled reactor.
The approval allows X-energy and Dow to continue finalizing and standardizing the reactor design, developing the supply chain for long-lead components and preparing the project’s operating license application.
The construction permit does not authorize the facility to load nuclear fuel or begin operating. Long Mott will need a separate NRC operating license after construction and before commercial operation.
Dow’s investment decision remains a major hurdle
Dow has emphasized that receiving the construction permit does not constitute a final decision to proceed with the project. The company expects to consider a preliminary investment decision in 2027, while continuing to evaluate the project’s competitiveness, execution readiness and capital affordability.
Full-scale nuclear construction would begin only after Dow makes its final investment decision. The company says construction could begin later this decade if the necessary investment and development milestones are achieved, with the first delivery of electricity and steam targeted for the early 2030s.
That distinction is particularly important for a first-of-its-kind industrial nuclear development. The permit establishes that the regulator has approved the construction stage, but the project must still pass Dow’s commercial and capital-allocation tests.
The companies have not disclosed a current total construction cost, a detailed engineering and construction contract or the commercial terms governing energy and steam supply to Dow. Those details will be important in assessing the project’s economics and the cost of replacing the existing energy assets.
Federal funding supports development, but costs have increased
Long Mott is being developed under the U.S. Department of Energy’s Advanced Reactor Demonstration Program, which supports the development and commercialization of advanced nuclear technologies.
X-energy’s securities filings identify an original estimated cost of approximately $2.4 billion for its broader ARDP program, with the Department of Energy providing up to $1.2 billion in 50/50 cost-share reimbursement for eligible costs under the original agreement. That program estimate covers more than the Long Mott plant alone, including reactor development and the TX-1 fuel fabrication facility.
X-energy has disclosed that its estimated program costs have increased since the original 2020 estimate because of inflation, supply-chain cost increases and changes in project scope. The company has also warned that future cost increases could require it and its partners to fund amounts beyond the available federal reimbursement.
In August 2026, X-energy announced an additional award of up to $1 billion in federal support, potentially bringing total public funding for the broader program to as much as $2.15 billion. The additional support is subject to cost-sharing requirements and should not be interpreted as a fully funded construction budget for Long Mott alone.
The funding arrangements underline the importance of federal support to the commercialization of advanced nuclear technology. They also leave open the question of how much additional private capital will be required to complete the project and bring the reactors into operation.
Operating license and technical work remain ahead
The construction permit does not complete the NRC’s oversight of Long Mott. The project must progress through the separate operating license process before the reactors can receive fuel and begin generating electricity.
X-energy and Dow say they will now continue design finalization, supply-chain development and preparation of the operating license application. The remaining licensing work will need to demonstrate that the completed facility meets the requirements for safe operation.
The project has also faced scrutiny during the regulatory process. The NRC’s environmental assessment and finding of no significant impact followed a formal review of potential environmental effects. The agency’s licensing process included a mandatory hearing, while a separate contested proceeding addressed a financial-qualification challenge raised by San Antonio Bay Estuarine Waterkeeper. These proceedings are distinct from the construction permit decision and should not be confused with a finding that the project has already secured its operating license.
The companies have not disclosed a final construction contractor, a detailed construction schedule or the complete list of major equipment suppliers. Those details will become increasingly important as the project moves from regulatory approval toward construction readiness.
Long Mott adds a new option for industrial energy supply
The proposed facility is part of a wider effort to develop new sources of dependable electricity and industrial heat as manufacturers and power producers seek to replace aging energy infrastructure and meet changing demand.
Hallador Energy, for example, is advancing its proposed 460 MW Turtle Creek natural gas project at the existing Merom Generating Station in Indiana. Hallador is targeting a final investment decision before the end of 2026, with commercial operation planned for the second half of 2028.
While Turtle Creek would use natural gas-fired generation, Long Mott would use advanced nuclear reactors to provide both electricity and process heat. The projects illustrate different technologies and development timelines being considered to supply industrial and regional energy needs.
For Dow, the central question is whether Long Mott can deliver reliable industrial electricity and steam at a competitive cost while meeting its construction and licensing requirements. For X-energy, the project represents a major step toward demonstrating its Xe-100 technology at commercial scale.
The next major milestone is Dow’s planned 2027 preliminary investment decision. Until the company commits the capital and the project advances through the remaining licensing stages, Long Mott remains a proposed nuclear development rather than a facility under full-scale construction.
Project factsheet: Long Mott Generating Station
- Developer: Long Mott Energy LLC, a wholly owned Dow subsidiary
- Technology partner: X-energy
- Location: Dow’s UCC Seadrift Operations site, Calhoun County, Texas
- Reactor technology: Xe-100 high-temperature gas-cooled reactor
- Number of reactors: Four
- Electrical capacity: 320 MWe combined
- Thermal capacity: 800 MWt combined
- Fuel: TRISO-coated particle fuel in graphite pebbles
- Regulatory milestone: NRC construction permit issued November 9, 2026
- Next investment milestone: Dow expects to consider a preliminary investment decision in 2027
- Target first energy delivery: Early 2030s
- Planned operating life: 60 years
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