The Nuclear Regulatory Commission (NRC) released its Final Safety Evaluation Report for the Long Mott Generating Station construction permit application on 30 October, after a comprehensive review of the Xe-100 plant’s principal design criteria, preliminary design, safety analyses, probabilistic risk assessment, and research and development programmes. The report documents the conclusion of the NRC staff that the proposed plant and site provide the safety basis to begin construction under US nuclear regulations.
The NRC completed its environmental review for the project in May, when it issued an Environmental Assessment and Finding of No Significant Impact. This means that both of the primary reviews needed for the NRC to approve the construction permit application have now been completed, X-energy said. With both primary reviews complete, the project moves to the final stages of the NRC’s construction permit review. On its social media channels, the regulator said its followers should “stay tuned for a construction permit announcement soon”.
Long Mott Energy, a wholly owned subsidiary of The Dow Chemical Company, submitted the construction permit application for the proposed plant – consisting of four Xe-100 high-temperature gas-cooled reactors, capable of generating a total output of 800 MWt or 320 MWe – in March 2025. The plant would be used to generate electricity and process steam for the Dow Chemical Company’s Seadrift Operations, exporting any excess power to the electrical grid: X-energy says this would make it the first grid-scale advanced nuclear reactor at an industrial facility in US history.
The commercial licensing effort for X-energy’s technology is supported by pre-application engagement with the NRC dating to 2018, as well as decades of US Department of Energy research on high-temperature gas-cooled reactor (HTGR) technology. The Xe-100 is the first HTGR construction permit application to use the NRC’s technology-inclusive, risk-informed, and performance-based licensing framework.
“Licensing a new reactor is earned through the quality of the application and the rigor of the regulator’s review,” said Dragan Popovic, Chief Global Operating Officer at X-energy. “The NRC’s completion of its safety review reflects years of disciplined work by our team and the NRC staff, establishing the foundations to support every Xe-100 application that follows on the path to scale.”
