X-Energy, Inc. (Nasdaq: XE) announced that Joel Duling will retire as president of TRISO-X, its nuclear fuels subsidiary, effective November 20, 2026, according to a company press release.

Duling, who has worked in nuclear operations, manufacturing, and program management for more than four decades, said he is stepping back to focus on his health, family, and personal priorities. He will remain with X-energy as a part-time senior advisor to CEO J. Clay Sell, supporting fuel partnerships, supply chain development, and the leadership transition.

Jason Hatfield, TRISO-X vice president and chief of staff, will assume interim leadership of the subsidiary. Dragan Popovic, X-energy's global chief operating officer, will continue to oversee construction of the TX-1 fuel fabrication facility as part of the Advanced Reactor Demonstration Program. The company said it is evaluating internal and external candidates for a permanent successor.

During Duling's tenure, TRISO-X advanced construction of what the company describes as the first purpose-built commercial TRISO fuel fabrication facility in the United States, located in Oak Ridge, Tennessee. The subsidiary also secured what X-energy claims is the first U.S. Nuclear Regulatory Commission license to commercially manufacture high-assay low-enriched uranium-based TRISO fuel, and submitted the first advanced nuclear fuel fabricated for commercial use to enter irradiation testing at Idaho National Laboratory's Advanced Test Reactor.

Construction of the TX-1 facility, a 214,000-square-foot building, recently completed its vertical construction phase. Work has moved to interior buildout, installation of fuel fabrication equipment, and construction of supporting facilities.

"Joel has been an extraordinary leader whose contributions have established a strong foundation for the future growth of TRISO-X," said CEO J. Clay Sell in the statement.