Thorium Atomics Inc. has officially commenced pre-application regulatory engagement with the U.S. Nuclear Regulatory Commission (NRC) for its Tesseract TGR advanced reactor, following the company's submission of a notice of intent letter. The NRC has assigned Project No. 99902174 and a dedicated project manager to coordinate the pre-application activities under the 10 CFR Part 53 framework, which became available on April 29, 2026.
The notice of intent, submitted on June 23, 2026, outlined the company's planned interactions with NRC staff. In response, the NRC designated a project manager in its Office of Advanced Reactors to facilitate the process. The project number serves as an administrative tracking reference for future correspondence, meetings, and submissions. 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 provided here.
It is important to note that the assignment of a project number is purely administrative and does not constitute submission or acceptance of a license application, nor does it represent NRC approval or endorsement of the Tesseract TGR design.
Thorium Atomics plans to engage under 10 CFR Part 53, the NRC's risk-informed, performance-based, and technology-inclusive licensing framework for commercial nuclear power plants. The company is preparing a Regulatory Engagement Plan detailing the Tesseract technology, its proposed licensing strategy, and the sequence of planned pre-application submissions.
Dr. Jack Vecchiarelli, Chief Scientific and Regulatory Officer, emphasized the significance 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 CEO, 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 high-temperature gas-cooled reactor rather than a conventional water-cooled design. It uses helium as a coolant and coated-particle TRISO fuel, an architecture where safety is driven by passive physical phenomena rather than active systems. The design is in development and has not yet been built, licensed, or independently validated.
With a thermal output of 250 MWth, the reactor delivers approximately 100 MWe of firm electricity or industrial process heat at temperatures up to 750 degrees Celsius—a temperature range that is difficult to supply with electricity and currently met almost entirely by combustion. The Tesseract TGR uses uranium TRISO fuel enriched below 10% U-235 as its initial fissile driver, and incorporates a thorium-bearing fertile blanket designed to capture neutrons and 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 while grounding the fuel and licensing pathway in established uranium and TRISO-fuel infrastructure. Current analysis estimates the architecture 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 and independent validation.
Thorium Atomics is an advanced nuclear reactor developer with offices in Toronto and Knoxville, and is conducting pre-application activities with both the U.S. NRC and the Canadian Nuclear Safety Commission. This engagement marks a critical step in the company's strategy to bring its innovative reactor design to market.
