The Manufacturing Demonstration Facility (MDF) at the U.S. Department of Energy's Oak Ridge National Laboratory, in collaboration with Kairos Power and Barnard Construction, has successfully developed and validated large-scale 3D-printed polymer composite formwork for casting complex, high-precision concrete structures, bringing transformative changes to nuclear infrastructure construction.

Traditional methods for producing these concrete structures are technically challenging and costly, whereas the newly developed 3D-printed formwork has been applied to the construction of Kairos Power's Hermes Low-Power Demonstration Reactor at its Oak Ridge campus—a significant milestone for the future of U.S. nuclear energy. The 3D-printed model for the Janus shield demonstration serves as a prototype for components of the Hermes reactor facility, with each component approximately 10 feet × 10 feet and stacked three units high to form columns. Partial column models were exhibited at the East Tennessee Economic Council's Nuclear Opportunities Workshop on July 22–23.

Workers from Barnard Construction poured concrete into carbon fiber-reinforced ABS formwork to create cast-in-place Janus columns. 3D-printed formwork enables innovative structural designs, significantly shortening production time and allowing complex structural components to be cast on-site in days—compared to traditional steel or wood formwork methods, which are costly, less precise, and take weeks. This shift represents a major advancement in nuclear power construction methods.

MDF Director Ryan Dehoff stated that they are demonstrating that the future of nuclear power construction does not have to follow past practices. By combining national laboratory capabilities with the MDF program, they are accelerating the development of new commercial nuclear energy.

Kairos Power Co-Founder and Chief Technology Officer Edward Blandford said that since the company's inception, it has collaborated with MDF, noting MDF's rapid action and creative thinking that deliver transformative results. While exploring prefabricated concrete system options, the company received recommendations from commercial partners to engage with MDF. MDF's collaborative approach supports Kairos Power in accelerating technology deployment through rapid learning cycles, improving methods and reducing risks by first building and testing tower column molds.

The Janus columns showcase novel design elements of the Hermes biological shield—a thick concrete structure built around the nuclear reactor to absorb radiation and protect workers. The project received support from multiple industry partners, including Airtech and TruDesign, jointly building a new supply chain for nuclear infrastructure. Barnard is responsible for implementing and adjusting the 3D-printed formwork, providing feedback and integrating design changes. Dehoff attributes the project's success to communication among partners.

These formwork must withstand heavy concrete pressure. Ahmed Arabi Hassen, leader of ORNL's Composites Innovation Team, stated that the challenge lies not only in geometric precision but also in maintaining structural integrity under high stress, pushing the limits of additive manufacturing in structural applications.

The project originated from the multi-year SM2ART Moonshot program, led by MDF and the University of Maine, funded by the U.S. Department of Energy's Advanced Materials and Manufacturing Technologies Office. The University of Maine has strengths in large-scale 3D printing, and the partners with Kairos Power aim to reduce risks and modernize nuclear power construction.

The project has national significance. The Knoxville-Oak Ridge region is the world's largest concentration of nuclear power enterprises, and the Hermes reactor is the first advanced reactor to receive a construction permit from the U.S. Nuclear Regulatory Commission, laying the foundation for Kairos Power's future commercial power plants and next-generation reactors.

Over the next 18 months, the SM2ART Moonshot project will continue supporting Kairos Power's construction, expanding to full production of radiation shielding and reactor building enclosures, integrating smart manufacturing technologies, and more. The partners' goal is to use printable biocomposite raw materials to reduce material costs by 75%. This project provides a vision for lowering costs and timelines for future reactors.