NRC Completes Safety Review of Xe-100 as Advanced Reactor Moves Toward Construction Permit
Advanced reactor developer X-energy announced on October 30 that the U.S. Nuclear Regulatory Commission (NRC) has completed its safety review for the initial deployment of the Xe-100 high-temperature gas-cooled reactor, issuing a Final Safety Evaluation Report. With the environmental review already complete, both primary reviews required for a construction permit are now done, and the project moves to the final stages of the NRC's construction permit review.
The report follows the NRC's review of the Xe-100 plant's principal design criteria, preliminary design, safety analyses, probabilistic risk assessment and research and development programs, and documents the staff's conclusion that the proposed plant and site provide the safety basis to begin construction under 10 CFR Part 50. The Advisory Committee on Reactor Safeguards, which advises the Commission independently, separately reviewed the staff's evaluation and supports issuance of the construction permit.
The Xe-100's safety case rests on the passive physics of its TRISO-X coated particle fuel and pebble-bed core. The design allows applicants to pursue a compact emergency planning zone of 400 meters, compared with 10 miles for conventional light-water reactors, enabling new generation to be sited closer to the point of need — including inside the perimeter of a large industrial facility. The NRC review establishes regulatory precedent for every Xe-100 project that follows.
The initial deployment is the proposed Long Mott Generating Station, advanced in partnership with Dow under the U.S. Department of Energy's Advanced Reactor Demonstration Program. X-energy says it would be the first grid-scale advanced nuclear reactor at an industrial facility in U.S. history. Pre-application engagement with the NRC dates to 2018, and the Xe-100 is the first high-temperature gas-cooled reactor construction permit application to use the NRC's technology-inclusive, risk-informed, performance-based licensing framework; its TRISO-X fuel builds on more than 20 years of U.S. Department of Energy testing data.
The NRC completed the project's environmental review in May 2026 with an Environmental Assessment and a Finding of No Significant Impact. In the United Kingdom, the Xe-100 was recently accepted into the Generic Design Assessment process. 'Licensing a new reactor is earned through the quality of the application and the rigor of the regulator's review,' said Dragan Popovic, X-energy's Chief Global Operating Officer. '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.'
Source: GSM · USA (original Chinese edition)
Photo: 图：TRISO包覆颗粒燃料剖面图。美国能源部，公共领域，经Wikimedia Commons。 / Cross-section of a TRISO coated fuel particle. U.S. Department of Energy, public domain, via Wikimedia Commons.
