Advanced reactor developer X-energy and global materials science company Dow have taken a major step in advancing their small modular reactor (SMR) project in Texas. The companies have officially submitted a construction permit application (CPA) to the U.S. Nuclear Regulatory Commission (NRC) for the Long Mott Generating Station, a pioneering advanced nuclear project at Dow’s Union Carbide Corp. (UCC) Seadrift Operations in Calhoun County.

The Long Mott project, spearheaded by Dow’s wholly owned subsidiary Long Mott Energy, will feature four Xe-100 high-temperature gas-cooled reactors (HTGRs), providing a total capacity of 320 MWe/800 MWth. First announced in May 2023, the initiative aims to showcase how advanced nuclear technology can supply carbon-free electricity and high-temperature steam to industrial sites like Dow’s 4,700-acre Seadrift facility, which produces over four billion pounds of chemical products annually.

X-energy’s Xe-100 operates at over 750°C, using a fuel system with 200,000 continuously cycling pebbles embedded with 18,000 TRISO particles. The compact reactor design retains over 99.99% of byproducts, eliminating the need for large containment structures. Helium, which does not become radioactive, drives the reactor’s steam turbine. The reactor is designed to operate for 60 years, delivering reliable baseload power.

If approved, the Long Mott Generating Station would become “the first grid-scale advanced nuclear reactor deployed to serve an industrial site in North America,” according to a joint statement from X-energy and Dow. Dow anticipates that the project will significantly reduce its Scope 1 and Scope 2 greenhouse gas emissions while strengthening the company’s long-term competitive advantage.

The project has received backing from the U.S. Department of Energy’s Advanced Reactor Demonstration Program (ARDP), which initially awarded X-energy $80 million in funding in 2020. The DOE has indicated it could invest up to $1.23 billion over seven years to support licensing, construction, and demonstration efforts for the Xe-100 reactor and its associated TRISO-X fuel fabrication facility. Initially planned for Washington state in partnership with Energy Northwest, the project transitioned to Dow’s Seadrift site in 2023.

The NRC is preparing to make the CPA public, but X-energy noted that the review process could take up to 30 months. This timeline could put construction on track to start later this decade, with operations expected in the early 2030s. “Throughout this process, we’ve been working to align the milestones of the gate review with the programmatic milestones of ARDP,” said Robert McEntyre, spokesperson for X-energy. “DOE has been agreeable to this alignment, and we believe this partnership with a proven project delivery organization provides the program with the best opportunity to be successful.”

A Landmark for Industrial Nuclear Power

The Long Mott CPA submission under the NRC’s Part 50 licensing process is a milestone for industrial firms looking to replace aging energy infrastructure with next-generation nuclear technology. “The energy assets [at the Seadrift site] are approaching their end of life, which is one of the reasons we turned to the SMR project,” said Daniel Womack, Dow’s global lead for Carbon Policy. “When we look at building out new assets, they need to last 20, 30, 40 years. It’s got to be something reliable, cost-competitive, and clean.”

While other advanced reactor projects have filed for construction permits—including Kairos Power in Tennessee and TerraPower in Wyoming—Long Mott is notable because it is the first commercial deployment of an advanced nuclear reactor designed specifically for an industrial customer. “We believe it demonstrates real progress, not just potential,” said McEntyre.

The project will also serve as a proving ground for X-energy’s broader commercial strategy. In October 2024, Amazon announced plans to support up to 5 GW of X-energy’s Xe-100 deployments by 2039, including investments and long-term power purchase agreements. Amazon’s commitment includes backing an initial 320-MWe Xe-100 plant in Washington state with Energy Northwest, with options to expand the project to 12 reactors.

Amazon’s investment includes $500 million in Series C-1 financing, with contributions from Citadel’s Ken Griffin, Ares Management, NGP, and the University of Michigan. X-energy has secured $1.1 billion in private capital since its 2020 ARDP selection, advancing design, licensing, and fuel fabrication efforts.

“Our partnerships with DOE, Dow, Amazon, among others, put us in a better position to realize that vision for all our customers,” McEntyre said. “ARDP has been essential in adding credibility and providing momentum for X-energy’s technologies, helping build the gateway for our subsequent projects and customers.”

Fuel Supply and TRISO-X Plant Development

As Long Mott progresses, X-energy is also advancing its TRISO-X fuel fabrication facility in Oak Ridge, Tennessee. The 215,000-square-foot TX-1 plant will be the first commercial-scale facility in North America dedicated to producing advanced TRISO nuclear fuel for reactors like the Xe-100. The facility will be capable of manufacturing up to 714,000 fuel pebbles per year, creating around 400 permanent jobs.

X-energy broke ground on the TRISO-X plant in 2022 and recently awarded a $40.8 million contract for site development, expected to be completed by mid-2025. The project is supported by ARDP funding and a $148.5 million Inflation Reduction Act tax credit.

McEntyre noted that the DOE will supply high-assay low-enriched uranium (HALEU) for Long Mott’s first core load and has awarded contracts to enrichment service providers to strengthen the HALEU supply chain. “This program, and its progress, have been key factors in helping our customers, Dow and Amazon included, move ahead with Xe-100 projects,” he said.

With these developments, X-energy is positioning itself as a leader in commercial advanced nuclear technology, with Long Mott serving as a critical step toward broader industry adoption.

Originally reported by Powermag.