US labs demo nuclear pressure vessel 3D-printed by three robots

Three robotic arms circled a metal shell at Oak Ridge National Laboratory, melting steel wire with electric arcs and building a vessel layer by layer. The MedUSA platform produced a roughly three-foot-by-five-foot enclosed pressure vessel in a steel alloy relevant to nuclear applications, a demonstration that ORNL and Idaho National Laboratory are now using to test a new route to large reactor hardware.

The work targets a practical bottleneck. Large pressure vessels are traditionally made through forging, but domestic forging capacity remains limited, creating potential supply challenges for the United States' nuclear expansion plans. Wire arc additive manufacturing — 3D printing that feeds molten metal wire into a structure — could offer manufacturers another way to produce these large components.

Printing the vessel is only the first hurdle. Pressure vessels must preserve their structural integrity under extreme pressure, heat and harsh operating conditions. ORNL and INL want to combine the robot platform with digital engineering and real-time monitoring, tracking a component's shape and material properties while it takes form.

Their goal is a “born-qualified” pressure vessel: one whose production data helps engineers assess whether it meets performance requirements before the manufacturing process ends. INL advanced manufacturing group lead Jorgen Rufner said the teams want to evaluate a component's performance as it is produced, while ORNL researcher Patxi Fernandez-Zelaia described the aim as assessing a part's suitability for extreme environments from data gathered during printing.

So what changes, concretely? If the approach proves reliable, reactor developers could gain another domestic manufacturing option for large, high-integrity metal components, potentially easing a supply constraint. The same methods could also serve chemical refining, oil and gas, defense and aerospace. For now, this is a demonstration vessel, not a component cleared for service: the labs still have to show that printed parts can meet demanding nuclear requirements and withstand years of operation.