The University of Maine is proving that large-scale 3D printing is rapidly becoming one of the most transformative tools in modern infrastructure development. When California-based Kairos Power set out to build its experimental Hermes nuclear reactor in Tennessee, the company faced a familiar challenge in nuclear construction: traditional methods were too slow, too rigid, and too expensive to meet its timeline. The solution came from UMaine’s Advanced Structures and Composites Center, home to one of the largest polymer 3D printers in the world.
The reactor’s design required enormous concrete form liners that followed a precise sinusoidal curve. Each wall section is three feet thick and twenty seven feet tall, demanding millimeter accuracy. Past approaches would have required complex machining and lengthy fabrication cycles. Instead, UMaine researchers used their super-sized polymer 3D printer to fabricate the longest forms the center has ever produced, custom printed from digital models and shaped for exact alignment with Kairos Power’s reactor geometry.
Once printed, the structures were precision-machined and inspected by UMaine’s metrology specialists. Every curve and angled surface was scanned and compared to the digital blueprint. According to ASCC chief sustainable materials officer Susan MacKay, the project left no room for deviations. She noted that the team achieved commercial-grade accuracy on a rapid schedule, calling it a milestone for an academic center operating at the pace of industry.
The partnership resulted in a hybrid casting system that significantly lowered costs and accelerated the entire construction sequence. By replacing traditional fabrication with additive manufacturing, the team shortened production cycles without compromising quality, making it possible for Kairos Power to stay on track with its reactor build. The approach also reduced material waste and created a repeatable process that can support future reactor projects.
The work is part of the Specialized Materials and Manufacturing Alliance for Resilient Technologies, also known as SM²ART, a collaboration involving UMaine and the Department of Energy’s Oak Ridge National Laboratory. Ryan Dehoff, director of the DOE Manufacturing Demonstration Facility, said the project shows how universities and national labs can give industry direct access to cutting edge tools and expertise essential for the next generation of energy infrastructure.
Beyond the physical components, UMaine researchers are also advancing digital assurance through the Material Process Property Warehouse. This AI-supported system tracks every step in the additive manufacturing process, creating a complete digital thread that allows components to be born certified. The approach aims to reduce regulatory delays and improve reliability for sectors such as nuclear power and defense.
As the nuclear industry looks for ways to build safer, faster, and more affordable reactors, UMaine’s work with Kairos Power offers a model for how large-format 3D printing can reshape heavy construction. With the Hermes project underway, UMaine has shown that additive manufacturing is no longer a future possibility for nuclear infrastructure. It is already on the job site.
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*All Photo Credits: University of Maine / UMaine Advanced Structures and Composites Center