NRC Completes Final Safety Review of Dow’s Texas SMR Project

The US Nuclear Regulatory Commission has completed its final safety evaluation of the Long Mott Generating Station, a proposed four-unit small modular reactor plant that Dow Chemical subsidiary Long Mott Energy wants to build at Dow’s Seadrift Operations site in Calhoun County, Texas. In a letter dated October 30, NRC staff concluded that the proposed design and site provide an adequate safety basis to begin construction, clearing the last major technical hurdle before the agency issues or denies a construction permit.

Four Reactors, One Industrial Site

Long Mott would use four of X-energy’s Xe-100 high-temperature gas-cooled reactors, each rated at 200 MWt (roughly 80 MWe), for a combined 800 MWt of thermal output across the site. The plant is designed to supply both electricity and process steam to Dow’s adjacent petrochemical complex, with any surplus power exported to the Texas grid. X-energy has described Long Mott as the first grid-scale advanced reactor project proposed at a US industrial facility, aimed at demonstrating that SMRs can directly serve heavy manufacturing rather than only utility-scale power generation.

The Xe-100 is a pebble-bed, helium-cooled design that runs at higher temperatures than conventional light-water reactors, which X-energy says makes it well suited to supplying industrial steam alongside electricity. Long Mott Energy filed its construction permit application with the NRC in March 2025, and the agency accepted it for formal review two months later.

What the NRC Has — and Hasn’t — Decided

A construction permit application requires both an environmental review and a safety review before the NRC can rule on it. The environmental side was completed in May, when the agency issued an Environmental Assessment and a Finding of No Significant Impact. The October 30 Final Safety Evaluation Report closes out the second and more technically demanding review, with NRC staff concluding that Long Mott’s proposed design and site “provide a safety basis to begin construction” under US nuclear regulations.

That is not the same as a construction permit. The NRC’s own account of the process makes clear that a final decision — covering any remaining licensing conditions, and following a mandatory hearing before the agency’s licensing board — is still to come. On social media, the NRC indicated only that an announcement on the permit was coming “soon,” without giving a firm date. Because the Xe-100 is the first high-temperature gas-cooled reactor design reviewed for a construction permit under the NRC’s newer risk-informed, performance-based licensing framework, the case has also drawn attention as a test of how that framework performs in practice; NRC pre-application engagement with X-energy on the design dates back to 2018.

Part of a Broader US Reactor-Siting Push

Long Mott is one of several X-energy-linked SMR proposals moving through US permitting at once. The company is separately studying a 960 MW Xe-100 project with utility AEP and Amazon at a retired coal plant site in Indiana, and it sits alongside a wider wave of advanced-reactor and fuel-supply investment in the US, including Westinghouse’s $1 billion low-enriched uranium fuel plant under construction in South Carolina. The industrial-siting model Dow and X-energy are pursuing at Long Mott also echoes proposals to use microreactors for dedicated, high-security loads such as US military bases, where the appeal is similarly about colocating generation with a specific, steady customer rather than feeding a wide grid.

Dow has pitched the project as a way to decarbonize steam and power supply at one of its largest US manufacturing sites without waiting for gas or grid alternatives, while X-energy has pointed to the safety evaluation’s completion as validation of design work that began with the Department of Energy’s Advanced Reactor Demonstration Program. Neither company has disclosed a total project cost; a construction-cost estimate circulating in trade press puts the figure near $2.4 billion, though neither Dow nor X-energy has confirmed that number publicly.

Sources

• US Nuclear Regulatory Commission, Final Safety Evaluation Report letter to Long Mott Energy LLC, Oct. 30, 2026 — safety basis conclusion, review scope.
• World Nuclear News, “Texas SMR plant moves to final permitting stage,” Nov. 2, 2026 — project description, timeline, NRC statements.
• X-energy Inc., investor release on NRC Final Safety Evaluation Report completion, Oct. 30, 2026 — reactor specifications, company statement.
• The Dow Chemical Company, press release on NRC Environmental Assessment finding, May 2026 — site and project purpose.

Illustrative image. Photo: Nuclear Regulatory Commission, Public domain, via Wikimedia Commons — source