Thorium Atomics Inc., an advanced nuclear reactor developer, announced today that it has commenced pre-application regulatory engagement with the U.S. Nuclear Regulatory Commission (NRC) for its Tesseract TGR advanced reactor. This follows the company's submission of a notice of intent letter on June 23, 2026, outlining its planned interactions with NRC staff. In response, the NRC assigned Project No. 99902174 and designated a project manager in its Office of Advanced Reactors to coordinate pre-application activities. The project number provides an administrative tracking reference for future correspondence, meetings, submissions, and staff reviews. The notice letter is publicly available in the NRC's Agencywide Documents Access and Management System (ADAMS) under Accession No. ML26189A392, accessible at https://www.nrc.gov/docs/ML2618/ML26189A392.pdf.
The assignment of a project number is an administrative step and does not constitute submission or acceptance of a license application, nor does it represent NRC approval, endorsement, or certification of the Tesseract TGR design. 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, which became available for use on April 29, 2026. The company is preparing a Regulatory Engagement Plan describing 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, stated, "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 of high-temperature reactor, using helium as a coolant and coated-particle TRISO fuel. Its advanced safety response is enabled by passive physical phenomena rather than active systems and high-pressure water infrastructure. The design is in development and has not yet been built, licensed, or independently validated. It is a small modular reactor designed for a thermal output of 250 MWth, delivering approximately 100 MWe of firm electricity or industrial process heat at temperatures up to 750 degrees Celsius. Heat at that temperature is difficult to supply with electricity and is currently met almost entirely by combustion.
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 capture neutrons that would otherwise leave the core and convert thorium-232 into fissile uranium-233 during operation. This uranium-fueled, thorium-augmented architecture is intended to diversify the nuclear fuel supply chain and improve lifetime uranium utilization while keeping the fuel and licensing pathway grounded in established uranium and TRISO-fuel infrastructure. Current analysis estimates that the architecture could reduce mined-uranium requirements by approximately half per unit of energy relative to a comparable Generation II light-water reactor. That estimate is subject to further engineering, design optimization, and independent validation using qualified analysis codes.
Thorium Atomics Inc. is an advanced nuclear reactor developer with offices in Toronto, Ontario, and Knoxville, Tennessee. The company is developing the Tesseract TGR, a uranium-fueled, pebble-bed high-temperature gas-cooled reactor designed to provide firm electricity and high-temperature industrial process heat. Tesseract augments its uranium fuel cycle with a thorium-bearing fertile blanket intended to improve lifetime uranium utilization by breeding uranium-233 during operation. Thorium Atomics is conducting pre-application activities with the U.S. Nuclear Regulatory Commission and maintaining a parallel regulatory pathway with the Canadian Nuclear Safety Commission. Further information is available at thoriumatomics.com.
