UMaine Uses Giant 3D Printer to Speed Nuclear Reactor Build

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.