The US Nuclear Regulatory Commission (NRC) has completed its Environmental Assessment (EA) for Dow and X-energy’s Construction Permit Application (CPA) for their proposed advanced nuclear project in Seadrift, Texas. The NRC review was completed ahead of schedule following a comprehensive independent analysis, concluding with a Finding of No Significant Impact (FONSI). This regulatory milestone marks a major step forward for the $2.4bn Seadrift advanced nuclear project.
The Long Mott Generating Station is being developed through Dow’s wholly-owned subsidiary, Long Mott Energy, under the Department of Energy’s (DOE’s) Advanced Reactor Demonstration Program (ARDP). The project aims to provide both electricity and high-temperature industrial steam to Dow’s UCC Seadrift Operations, supporting the production of more than 4bn pounds of materials a year.
The Seadrift Advanced Nuclear Project is rooted in X-energy’s long-term development of its Xe-100 high-temperature gas-cooled reactor (HTGR). The 80 MWe system is designed to use helium as its coolant and tri-structural isotropic (TRISO) particle fuel alongside passive, inherently safe shutdown mechanisms.
If approved, X-energy’s Xe-100 would signal a US return to a HTGR technology that was abandoned 1989. In 1966, General Atomics (GA) built a demonstration 40 MW HTGR at the Peach Bottom Atomic Power Station in Pennsylvania but shut it down 1974. GA also started a 330 MW HTGR project around the same time at Colorado’s Fort St Vrain nuclear plant that came online in 1979 but lasted only 10 years because of repeated technical malfunctions and steep repair costs.
X-energy began formally engaging with NRC in 2016 to establish a regulatory baseline for its non-light-water small modular reactor (SMR) design. The venture shifted from an engineering concept to a commercialisation pathway in 2020, when it was selected for the ARDP. This provided a 50/50 cost-share framework covering up to $2.4bn in total estimated development expenses.
In 2022, multinational chemical and materials science manufacturing company Dow became X-energy’s first major commercial offtaker. In 2023 Dow and X-energy sign an official Joint Development Agreement, including a $50m initial investment fund to kick off site-specific engineering.
Dow officially designated its 4,700-acre UCC Seadrift Operations manufacturing site in Texas to host the project, seeking a high-volume, reliable source of zero-carbon electricity and high-temperature steam to satisfy its decarbonisation targets. The facility will provide 320 MWe of clean electricity and up to 800 MW of high-temperature thermal power. In April 2026, X-energy signs a major engineering, procurement, and construction contract with Fluor Corporation to advance the plant layout.
While Dow hosts the Seadrift project in Texas, Amazon is concurrently backing an initial 320 MWe Xe-100 project with Energy Northwest in Washington State to power local operations. In 2024, Amazon announced its landmark entry into advanced nuclear power. Its Climate Pledge Fund anchored a $500m Series C-1 funding round for X-energy. Amazon and X-energy finalise a commercial framework agreement to bring 5 GWe of SMR capacity online by 2039 and Amazon signed a development agreement with Energy Northwest for the Washington State project.
The FONSI conclusion on the EA follows an extensive independent analysis by NRC staff, evaluating potential impacts to air quality, water resources, and local species habitats under globally recognised safety and environmental standards. NRC completed its environmental review in less than a year, benefiting from X-energy’s pre-licensing work on the XE-100 and a comprehensive CPA submittal that met federal requirements.
The CPA included a more than 1,000-page Environmental Report supported by year-long field surveys, groundwater monitoring wells with 12 months of water quality measurements, and engagement with multiple state agencies.
“This is a significant milestone for the Long Mott Energy project and we appreciate the comprehensive and efficient manner in which the NRC conducted its assessment,” said Edward Stones, Business Vice President for Energy & Climate at Dow.
Dragan Popovic, Chief Global Operating Officer at X-energy said the approval establishes a replicable pathway for increased efficiency in the licensing process “built through years of preparation to demonstrate the strong safety profile of our technology”. He added: “There are no shortcuts in nuclear safety. Every efficiency has to be earned, and it begins with a complete, high-quality application and technology designed to be intrinsically safe.”
The environmental approval is the first of the two stages in the construction permitting process and is a requirement to complete the second stage safety review. X-energy expects NRC’s staff to issue recommendations on the safety review in November.
The accelerated process for the Seadrift Advanced Nuclear Project reduces traditional permitting timelines by around a half. Historically, the agency has taken several years to evaluate and issue nuclear construction permits. However, the NRC committed to a strict 18-month safety and environmental review schedule for the Dow and X-energy application.
This was supported by a number of legislative and administrative mandates. These include the Accelerating Deployment of Versatile, Advanced Nuclear for Clean Energy (ADVANCE) Act, which aims to protect public safety while preventing regulatory delays that block reactor construction. Executive Orders issued in May 2025 further pushed NRC to deepen its regulatory changes to spur next-generation reactor construction. To remove financial barriers for innovative companies, NRC also slashed its regulatory and application fees by 50% for advanced reactor applicants for the 2025 fiscal year. Under newly updated rules, NRC allows commercial applications to directly reference prior research, safety authorisations, and testing conducted by DOE.
Another factor was the Technology-Inclusive Content of Application Project (TICAP) guidance framework that shifts reviews away from rigid, legacy light-water reactor standards toward a risk-informed, performance-based focus tailored to advanced reactor attributes. This aligns with the newly enacted 10 CFR (Title 10 of the Code of Federal Regulations) Part 53 licensing framework. Title 10 is divided into hundreds of chapters and parts that dictate specific legal requirements.
The newly enacted Part 53 introduced a new framework specifically designed for advanced, non-light-water commercial reactors in contrast to Part 50, legacy rules used to license traditional, large light-water NPPs. This represents the most substantial re-thinking of commercial nuclear regulation since the 1950s by legalising technology-inclusive pathways.
The proposed Part 57 represents a further major regulatory shift toward matching regulatory requirements to real-world risk. The proposed rule would enable high-volume, rapid deployment of microreactors (generally 100 megawatts or smaller) and other “low-consequence” advanced reactor designs. As a result, NRC is now able to operate multiple licensing frameworks in parallel.
“We’re proving that we can use these regulatory processes and get an acceptable outcome in a timely and efficient manner,” X-energy said. “It’s about the experience you bring to the project and the talent you apply to it, and the teams that are built on it that allow companies to succeed. The regulatory process is what it is—and the NRC is willing to work with us on that path now.”
X-energy cited the Long Mott review as evidence of a more workable dynamic between regulators and applicants. “The NRC has been a great independent but collaborative partner in this journey,” X-energy said. “They saw the work that we did, they appreciated it, and they worked with us on this path to achieve this first-of-a-kind licensing activity.”
