ORNL's MedUSA Printer Uses Three Robotic Arms to 3D Print a Nuclear Pressure Vessel

Three arms, one vessel

The United States is running short on the heavy forging capacity needed to build new nuclear reactors. Oak Ridge National Laboratory and Idaho National Laboratory think large-scale metal 3D printing could be part of the answer. Their latest demonstration used MedUSA, a manufacturing platform that coordinates three robotic arms, to print a nuclear-relevant pressure vessel roughly three feet by five feet.

The system uses wire arc additive manufacturing, melting steel wire with electric arcs to build up complex metal structures. For this test, the team printed an enclosed vessel in a steel alloy relevant to nuclear applications. The part represents an early step toward using additive manufacturing for components traditionally produced through forging.

Born-qualified parts

The real challenge is not just printing the vessel. It is proving it can survive years of heat, pressure, and radiation. ORNL and INL plan to combine large-scale additive manufacturing with digital engineering and real-time monitoring. The goal is to create what ORNL calls born-qualified pressure vessels, using production data to evaluate whether a component meets performance requirements while it is still being built.

That approach could reduce the long testing cycles that follow conventional manufacturing. INL is contributing expertise in nuclear materials, digital engineering, and data science. Jorgen Rufner, INL's advanced manufacturing group lead, said the team wants to evaluate a component's performance as it is produced, shortening qualification timelines.

From microreactors to heavy hardware

This is not the first time ORNL has tested MedUSA for nuclear work. The lab previously used the same platform and material system to produce neutron sensor brackets for Antares Nuclear's R1 Mark-0 microreactor, which reached criticality at INL in June. The pressure vessel project is a much larger application of the same ideas.

Success here could expand beyond nuclear energy. Aerospace, defense, chemical processing, and oil and gas all need large, high-integrity metal parts built for demanding environments. If wire arc additive manufacturing can reliably produce and qualify pressure vessels, it would give US manufacturers an alternative route when forging capacity is booked out.