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 reactor. The company submitted a notice of intent letter on June 23, 2026, and the NRC responded on July 24, 2026, assigning Project No. 99902174 and a project manager to coordinate pre-application activities. 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 (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 or endorsement of the Tesseract 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 detailing 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 early engagement: "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 type of high-temperature gas-cooled reactor, using helium as a coolant and coated-particle TRISO fuel. It is 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. This high-temperature heat is currently supplied almost entirely by combustion, so the reactor could offer a low-carbon alternative for industrial processes.
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 architecture aims to diversify the nuclear fuel supply chain and improve lifetime uranium utilization, potentially reducing mined-uranium requirements by approximately half per unit of energy compared to a comparable Generation II light-water reactor. However, this estimate is subject to further engineering, design optimization, and independent validation using qualified analysis codes.
Thorium Atomics is also maintaining a parallel regulatory pathway with the Canadian Nuclear Safety Commission. The company is headquartered in Toronto, Ontario, and Knoxville, Tennessee. The Tesseract TGR is still in development and has not yet been built, licensed, or independently validated.
The initiation of pre-application engagement with the NRC marks a significant step for Thorium Atomics, as it navigates the new Part 53 licensing framework designed for advanced reactors. By engaging early, the company aims to clarify regulatory expectations and reduce uncertainties in the licensing process, which could accelerate the deployment of advanced nuclear technology in the United States.
