(ORNL: Oak Ridge, TN) -- In a bold step toward transforming how nuclear infrastructure is built, the U.S. Department of Energy’s Manufacturing Demonstration Facility, or MDF, at Oak Ridge National Laboratory, in partnership with Kairos Power and Barnard Construction, has successfully developed and validated large-scale, 3D-printed polymer composite forms for casting complex, high-precision concrete structures that would be technically challenging and costly to produce using conventional methods. The concrete forms are being used at Kairos Power’s Oak Ridge campus, where the Hermes Low-Power Demonstration Reactor is currently under construction—a milestone for the future of American nuclear energy.

The 3D-printed forms for the Janus shielding demonstration are precursors to those that Kairos Power and Barnard will employ to construct parts of the Hermes reactor facility. Each section measures roughly 10 ft x 10 ft and is stacked three units high to create a column.

Barnard Construction workers pour concrete into the carbon-fiber-reinforced ABS form to produce one of the cast-in-place Janus columns. Credit: Kairos Power

Enabling innovative structural designs, the use of 3D-printed forms or molds is a leap forward in infrastructure-scale construction that Kairos Power intends to leverage at a larger scale for its future commercial plants. The composite forms dramatically cut down production timelines, enabling “cast-in-place” construction of complex structural components with unique geometries in days rather than weeks. Compared to traditional methods relying on steel or wood forms that can be costly, imprecise, and time-consuming to build, this shift marks a significant advancement in nuclear construction methodology.

“At ORNL, we’re showing that the future of nuclear construction doesn’t have to look like the past,” says Ryan Dehoff, director of the Manufacturing Demonstration Facility. “We’re combining national lab capabilities with MDF’s legacy of taking big, ambitious swings—moonshots that turn bold ideas into practical solutions—to accelerate new commercial nuclear energy.”

During the last decade, MDF has led major first-of-their-kind efforts, from 3D-printing cars and homes to creating digital tools that qualify parts in real time. These moonshots have helped redefine what’s possible in manufacturing—and now they’re being applied to the challenges of modernizing nuclear energy.

“We’ve had a relationship with MDF since Kairos Power’s formation,” says Edward Blandford, co-founder and chief technology officer of Kairos Power. “They move fast, they think creatively, and they’ve demonstrated that they can deliver transformative results when conventional manufacturing would fall short.”

Blandford explained that while exploring options for precast concrete systems, Kairos Power received a recommendation from a commercial partner to talk with MDF. “It’s not often we get advice from industry to call the national lab because they move quickly.”

The MDF’s collaborative approach supports Kairos Power’s focus on using rapid learning cycles to accelerate technology deployment.

“This project fits squarely into our iterative development approach,” Blandford says. “By building and testing the molds for the columns first, we’re able to refine our methods, engage early with regulators, and reduce risk before we scale up the construction method for Hermes and future plants. That’s been a core part of our strategy from Day One.”

Kairos Power’s Janus column demonstrates an element of the company’s novel design for the Hermes bioshield – the thick concrete structure built around a nuclear reactor that absorbs radiation during operation, protecting workers.

The project was supported by multiple industry partners, including Airtech Advanced Materials Group, TruDesign, Additive Engineering Solutions, and Haddy, which collectively established a new supply chain for nuclear infrastructure enabled by additive manufacturing. Barnard played a key role, implementing and adapting the 3D-printed formwork, providing real-time feedback, and incorporating design changes on the fly to enhance constructability and enable rapid deployment. Dehoff says that the project’s success stemmed from communication between the partners. “It’s a real example of national lab innovation in action,” he says.

The forms had to withstand the tremendous pressure exerted by the heavy concrete they were designed to shape. ORNL’s Ahmed (Arabi) Hassen, group leader for composites innovation, says that the challenge wasn’t just about geometric precision—the molds needed to maintain their structural integrity under high stress. This required both mechanical resilience and innovative design and printing strategies, pushing the limits of what additive manufacturing can achieve for structural applications.

The project exemplifies how advanced manufacturing is being used to modernize one of the most traditional construction sectors in American infrastructure. “We’re taking the best of additive manufacturing—modularity, flexibility, rapid iteration—and applying it to nuclear energy,” Hassen says. “This project shows that we can break through old methods with new technologies that lower barriers, reduce risk, and accelerate construction timelines.”

The collaboration with Kairos Power was enabled by a broader, multiyear initiative called the SM2ART Moonshot Project, led by MDF and the University of Maine, and funded by the U.S. Department of Energy’s Advanced Materials and Manufacturing Technologies Office. The project leverages ORNL’s unique combination of world-class materials science expertise, supercomputing and artificial intelligence resources, and large-format additive manufacturing capabilities. The University of Maine brings complementary strengths in large-scale 3D printing, structural infrastructure development, and digital manufacturing platforms. Together with Kairos Power, the partners aim to de-risk and modernize nuclear construction through rapid, flexible, and cost-effective solutions.

Looking down on the Janus gate from above, the 3D-printed form is visible next to the concrete pillars arranged in a radiation symbol. Credit: Kairos Power

This project has national significance. The Knoxville-Oak Ridge region is the world’s largest hub of nuclear-focused companies, and Hermes is the first advanced reactor to receive a construction permit from the U.S. Nuclear Regulatory Commission. It lays the groundwork for Kairos Power’s future commercial plants and a new generation of reactors that will play a pivotal role in meeting surging U.S. energy demands in the coming decades.

During the next 18 months, the SM2ART Moonshot Project will continue to support Kairos Power construction initiatives, expanding to include full-scale production of forms for radiation shielding and reactor building enclosures, and integrating smart manufacturing techniques, digital twins, and data-driven quality control. The partners aim to use printable biocomposite feedstocks derived from timber residuals, targeting a 75% reduction in material cost using domestic forest products.

By demonstrating that nuclear construction can adopt manufacturing practices—from design agility to rapid deployment—the project offers a compelling vision for lowering the cost and timeline of future reactors.

The MDF, supported by the U.S. Department of Energy’s Advanced Materials and Manufacturing Technologies Office, is a nationwide consortium of collaborators working with ORNL to innovate, inspire, and catalyze the transformation of U.S. manufacturing. Learn more about working with the MDF. For more information, visit energy.gov/science.