Thorium Atomics Inc., a developer of advanced nuclear reactors, announced today that it has commenced pre-application regulatory engagement with the U.S. Nuclear Regulatory Commission (NRC) for its Tesseract TGR advanced reactor. The company submitted a notice of intent letter on June 23, 2026, outlining its planned interactions with NRC staff. In response, the NRC assigned Project No. 99902174 to the Tesseract TGR and designated a project manager in the NRC’s Office of Advanced Reactors to coordinate pre-application activities, as confirmed by a letter dated July 24, 2026.
The assignment of a project number is an administrative step that provides a tracking reference for future correspondence, meetings, and submissions. It does not constitute submission or acceptance of a license application, nor does it represent NRC approval, endorsement, or certification of the Tesseract TGR design. The notice letter is publicly available in the NRC’s Agencywide Documents Access and Management System (ADAMS) under Accession No. ML26189A392, with a direct link at https://www.nrc.gov/docs/ML2618/ML26189A392.pdf.
Thorium Atomics plans to engage with the NRC under 10 CFR Part 53, the agency’s risk-informed, performance-based, and technology-inclusive licensing framework for commercial nuclear power plants. Part 53 became available for use on April 29, 2026, and is designed to accommodate advanced reactor technologies. The company is preparing a Regulatory Engagement Plan that will describe the Tesseract technology, its proposed licensing strategy, and the sequence of planned pre-application submissions.
Dr. Jack Vecchiarelli, Chief Scientific and Regulatory Officer at Thorium Atomics, emphasized the importance of this milestone: “A project number and an assigned project manager give us a defined NRC point of contact and a trackable reference for our future pre-application work. Part 53 is risk-informed and technology-inclusive, making it well suited to a high-temperature gas-cooled reactor. Commencing that engagement while the design is still being developed serves to ensure that regulatory expectations are clearly understood and addressed, thereby informing the design development process and helping to de-risk the future licensing pathway.”
Young Hwang, Founder and Chief Executive Officer, added, “This is a clear external marker of where our program stands. It comes alongside our application to Idaho National Laboratory’s Nuclear Energy Launch Pad program and our proposed pathway for independent, qualified-code reactor-physics verification at a U.S. national laboratory. We are deliberately building the regulatory, engineering, and technical-validation records in parallel.”
The Tesseract TGR is a pebble-bed type high-temperature reactor that uses helium as a coolant and TRISO particle fuel. This design relies on passive physical phenomena for safety rather than active systems and high-pressure water infrastructure. It is a small modular reactor with a thermal output of 250 MWth, delivering approximately 100 MWe of firm electricity or industrial process heat at temperatures up to 750 degrees Celsius. Such high-temperature heat is currently supplied almost entirely by combustion, making the Tesseract a potential low-carbon alternative for industrial applications.
The reactor uses uranium TRISO fuel enriched below 10% U-235 as its initial fissile driver and incorporates a thorium-bearing fertile blanket designed to convert thorium-232 into fissile uranium-233 during operation. This uranium-fueled, thorium-augmented architecture aims to diversify the nuclear fuel supply chain and improve lifetime uranium utilization. Current analysis estimates that the design could reduce mined-uranium requirements by approximately half per unit of energy relative to a comparable Generation II light-water reactor, though this estimate is subject to further engineering, design optimization, and independent validation using qualified analysis codes.
Thorium Atomics, with offices in Toronto, Ontario, and Knoxville, Tennessee, is conducting pre-application activities with the NRC while also maintaining a parallel regulatory pathway with the Canadian Nuclear Safety Commission. The company’s engagement with the NRC under Part 53 is a significant step toward licensing an advanced reactor that could contribute to decarbonizing electricity and industrial heat production. As the design is still in development and not yet built or licensed, the pre-application process will help clarify regulatory expectations and address potential issues early, potentially streamlining the path to deployment.
