X-energy, a U.S. reactor developer, and chemical giant Dow announced on November 9, 2026, that they have received a construction permit from the U.S. Nuclear Regulatory Commission (NRC) for four small reactors planned in Texas. The project would replace aging power and steam supply equipment at a Dow chemical plant with next-generation small reactors. The permit means the project has cleared a key regulatory stage on the way to construction.
However, a construction permit authorizes building reactors based on an approved design. It does not mean Dow has decided to invest in construction, nor does it authorize operation. Full-scale construction requires a final investment decision by Dow, and loading fuel and starting up the reactors will require a separate NRC operating license. Important regulatory and business decisions remain before the four reactors can supply power and high-temperature steam to the chemical plant.
Four small reactors to supply power and high-temperature steam to a chemical plant
The project covers the "Long Mott Generating Station," which Long Mott Energy, a wholly owned subsidiary of Dow, plans to build at the "UCC Seadrift Operations" chemical manufacturing site in Texas. It is being advanced under the U.S. Department of Energy's (DOE) Advanced Reactor Demonstration Program (ARDP). According to X-energy and Dow, it is the first construction permit issued for an advanced reactor at a U.S. industrial facility. The companies also say it is the first construction permit for a high-temperature gas-cooled reactor in about 60 years, and the first approval for a pebble-bed high-temperature gas-cooled reactor. These are achievements tied to obtaining the construction permit, however, and do not mean the reactors have been completed or are operating.
The planned reactor is the "Xe-100," a high-temperature gas-cooled reactor developed by X-energy. Each unit is designed for 80 MWe of electrical output and 200 MWt of thermal output, so four units total 320 MWe and 800 MWt. MWe refers to generating capacity and MWt to the scale of heat the reactor produces, so the two cannot simply be added together as total supply. Nor does thermal output directly indicate the amount of heat that can be delivered to the plant as steam. These are nominal design values, and the public materials reviewed contained no specifics on the amounts or split of electricity and steam actually delivered to the plant.
A distinguishing feature of the project is that the reactors would be used not only to generate electricity but also to supply the high-temperature industrial steam the chemical plant needs. Replacing existing power and steam equipment requires not just building reactors but also putting in place a configuration that can reliably deliver the plant's electricity and heat. The companies aim to begin supply in the early 2030s and envision the reactors supplying energy for 60 years. Both are current business plans, however, and neither the actual start of supply nor its duration has been settled.
The Xe-100 will use "TRISO-X," a coated particle fuel designed to contain radioactive material with multiple coating layers. By building several barriers against radioactive release into the fuel itself, the design aims to enhance safety. Still, these safety design features need to be distinguished from the regulatory review required to build and operate the actual facility.
Prior consultations and an 18-month review led to the permit
The path to the permit involved long-running consultations with the regulator. X-energy has been engaged in pre-application discussions with the NRC since 2018, and Dow since 2023. Long Mott Energy then applied for the construction permit on March 31, 2025, and the NRC formally docketed the application on May 12 of that year. On June 10, a review schedule was set, and a review of about 18 months followed. The NRC's published review progress also confirms the docketing of the application and the setting of the schedule.
According to the official FAQ published by X-energy, the construction permit was issued through a process under 10 CFR Part 50, and the safety and environmental reviews were completed. The environmental review was conducted under the procedures of 10 CFR Part 51. The companies say the review proceeded according to the planned schedule, and the NRC says it met the 18-month review period. That period, however, refers to the review process after the application was docketed and does not include the time spent on reactor development or pre-application consultations.
The FAQ also says more than a dozen technical reports were approved during pre-application discussions, and that they could serve as reference material for future reactor projects. Such an accumulation of technical documentation could make reviews of follow-on projects using the same design more efficient. However, this construction permit does not automatically authorize construction of follow-on projects, nor does it guarantee a shorter review period.
Investment decision and operating license still ahead
Between construction and the start of operation, there are distinct stages: the construction permit, the investment decision, and the operating license. Obtaining the NRC construction permit is a major regulatory milestone, but whether to commit funds to construction rests on Dow's business judgment. Further, after construction, a separate NRC operating license is required before fuel can be loaded and the reactors started up.
| Decision item | Decision maker | Status as of Nov. 9, 2026 | Meaning and remaining conditions |
|---|---|---|---|
| Construction permit | NRC | Companies announced it has been obtained | Authorizes construction based on the approved design. Does not authorize operation |
| Preliminary investment decision | Dow | Expected to be considered in 2027 | A stage to assess project feasibility and investment terms. Not a final decision to build |
| Final investment decision | Dow | Not yet decided | Dow decides whether to proceed to full-scale construction after finalizing design and engineering, board review, and other steps |
| Operating license | NRC | Must be obtained | Required after construction, before fuel loading and reactor startup |
It is worth noting that what is planned for 2027 is a preliminary investment decision, and the timing of the final investment decision and the start of construction has not been fixed. In its official announcement (MarketScreener reprint), Dow states explicitly that obtaining the construction permit does not mean a final decision to build. Before moving to actual construction, it must finalize the design and engineering and go through steps such as board review.
For small reactor construction to work as a business, regulatory permits are not enough; design maturity, construction costs, and procurement of components also matter. In this announcement, X-energy and Dow say they will move ahead with finalizing and standardizing the Xe-100 design, building out the supply chain for long-lead equipment and materials that take a long time to manufacture and deliver, and preparing the operating license application to be submitted to the NRC. For a first-of-its-kind deployment in particular, design changes or procurement problems could lead to higher construction costs or schedule delays. And because the plan replaces existing power and steam equipment, whether the plant's equipment renewal timing can be matched with the start of supply from the new reactors is also an important issue.
The companies plan to reduce the risk of schedule delays and cost increases after groundbreaking by advancing design, equipment, and materials preparation before committing major funds to full-scale construction. How much risk this preparation will actually reduce cannot be determined from the announcement. The construction permit is only a regulatory approval, and whether construction ultimately goes ahead depends on Dow's investment decision.
The focus: a 2027 investment decision and supply starting in the early 2030s
Dow plans to evaluate the project's competitiveness as a business, its readiness to execute, and the reasonableness of the required capital burden. Its announcement also indicates that, if the necessary approvals are obtained, construction could begin in the late 2020s and the reactors could start up in the early 2030s. This is a conditional timeline premised on future investment decisions, however, and neither the start of construction nor the start of operation has been formally decided.
Information for evaluating the project's profitability is also limited at this point. The public materials reviewed contain no specific figures on total construction cost, unit prices for electricity and steam, the volume of steam supplied to the plant, or investment returns. Because the plan involves switching both electricity and steam from existing equipment, the reactors' nominal output alone is not enough to judge how much energy the plant would actually receive or at what cost. Once these conditions are clarified, a more concrete assessment of the economic rationale for replacing conventional equipment will become possible.
The companies cite design changes, additional permitting, financing, profitability, longer construction periods, and cost increases as future risks. The supply chain for components and materials and government support are also factors that could affect how the plan progresses. The permit is an important step toward deploying small reactors at industrial facilities, but it does not guarantee that the plan will be realized or that operations will begin. The next milestone is the preliminary investment decision in 2027; whether the reactors will ultimately supply power and steam to the chemical plant will depend on the final investment decision, the firming up of supply terms, and the securing of an operating license.