Construction Permit for Dow’s Four-Reactor Nuclear Project Moves Long Mott Into Preparation Phase
Key Facts
Long Mott, a nuclear project being developed by Dow subsidiary Long Mott Energy, has received a construction permit from the U.S. Nuclear Regulatory Commission, according to a Nov. 9 report cited in the available material. The permit moves the proposed project at Dow’s chemical plant in southeast Texas into the construction preparation phase, following regulatory reviews covering safety and the environment. The project comprises four Xe-100 reactors, according to the U.S. Department of Energy. The permit allows site preparation, concrete work below ground level and installation of safety-related components, according to X-energy. It does not authorize operation of the units, which will require separate operating licenses.
The permit was issued after X-energy announced on Oct. 30 that the commission had completed its safety review of the project. According to the company, the final evaluation report covered preliminary design criteria, safety analyses, probabilistic risk assessment, and research and development programs. The Advisory Committee on Reactor Safeguards also reviewed commission staff’s assessment and endorsed issuance of the construction permit, according to an X-energy statement. The commission completed its environmental assessment on May 18, 2026, concluding that there was “no significant impact,” according to the company. X-energy said the environmental review took less than a year and included an independent analysis of potential effects on air quality, water resources and local species’ habitats.
The project includes four reactors at Dow’s chemical plant and combines electricity generation with industrial process heat. Each reactor can produce 80 megawatts of electricity or 200 megawatts of thermal energy and is designed to operate for 60 years, according to the Department of Energy. X-energy said the project aims to supply electricity and high-temperature industrial steam to Dow’s site in Seadrift. The site produces more than 4 billion pounds of materials annually, according to the company. The proposed nuclear power would serve a high-output industrial site, with electricity and process heat supporting its operations.
The Nuclear Regulatory Commission set an 18-month review period for Dow’s project application, under a licensing timeline for advanced reactors, according to the commission’s Licensing Modernization Project page. X-energy announced completion of the environmental review in May and then announced completion of the safety review in October. In a filing with the Securities and Exchange Commission, the company expected regulatory review to be completed in late 2026 and the construction permit to be issued in the first quarter of 2027. In the same filing, it expected construction to begin during 2027, subject to obtaining the permit and required approvals. It also set a target for commercial operation in the early 2030s.
According to X-energy, the construction permit allows site preparation, below-grade concrete work and installation of safety-related structures, systems and components. Operating the reactors requires a separate application for an operating license, as the Nuclear Regulatory Commission explained in its notice on the availability of a hearing request for the project. The company says operating licenses are issued after construction is complete and a final safety inspection. People who could be affected by the project could request to intervene in a hearing on the permit application until Aug. 11, 2025, according to the commission’s notice. The construction and commercial-operation dates in the company’s filing remain targets and are conditional on completing the required approvals.