X-energy said Joel Duling will retire from full-time executive leadership as president of TRISO-X, its wholly owned nuclear fuels subsidiary, effective November 20, 2026. Duling will remain a part-time employee and senior advisor to Chief Executive Officer J. Clay Sell, focusing on strategic fuel partnerships, fuel supply chain development and the transition to a permanent successor. Jason Hatfield, TRISO-X’s vice president and chief of staff, will assume interim leadership, while Global Chief Operating Officer Dragan Popovic will continue overseeing integration and construction of the TX-1 fuel fabrication facility. X-energy is evaluating internal and external candidates. TRISO-X has advanced construction of TX-1, secured the first U.S. Nuclear Regulatory Commission license to commercially manufacture high-assay low-enriched uranium-based TRISO fuel, and submitted commercial-use fuel for irradiation testing at Idaho National Laboratory’s Advanced Test Reactor. Vertical construction of the 214,000-square-foot facility in Oak Ridge, Tennessee, has been completed, with interior buildout and equipment installation now underway.