NRC staff finish Long Mott Xe-100 safety review; permit decision pending

NRC staff issued the final safety evaluation for Long Mott Generating Station on October 30, 2026, recommending the Commission make the findings needed to grant Dow subsidiary Long Mott Energy a construction permit for four X-energy Xe-100 small modular reactors in Calhoun County, Texas. The staff finds the preliminary design "sufficient to meet the applicable regulatory requirements for the issuance of a CP in accordance with 10 CFR 50.35," subject to certain conditions. The four high-temperature gas-cooled reactors total 800 MWt, or 320 MWe, and would supply electricity and process steam to Dow's Seadrift Operations, exporting any excess to the grid.

The staff proposes two permit conditions, both about the site: geologic mapping of each foundation excavation for safety-related structures, and notice to the NRC when the site grading and passive flood protection designs are ready for examination. Further design and analysis information, the staff writes, "can reasonably be left for later consideration" in the final safety analysis report, which comes with an operating license application. None of this is a permit: the transmittal letter says issuing the evaluation "does not constitute a commitment to issue the CP."

The evaluation landed before the November 2026 target on the NRC's project page, and after the hearing. Written questions sent in after the uncontested mandatory hearing on September 22 in Port Lavaca got their answers by reference: the NRC's summary points them to the safety evaluation, then still to come, and the environmental assessment. The Advisory Committee on Reactor Safeguards backed issuance on October 16 (as we reported). The licensing board terminated the contested proceeding on June 25, and San Antonio Bay Estuarine Waterkeeper petitioned the Commission to review that ruling. A Commission order on a separate appeal took no position on the petition, and no ruling on it appears in the docket's public record as of October 30.

X-energy says the project "moves to the final stages of the NRC's construction permit review." A permit would be the first for any Xe-100. The same release's list of cautionary factors includes whether X-energy's customers, including Dow, decide to proceed with construction.