ORNL Uses Three Robotic Arms to 3D Print a Steel Nuclear Pressure Vessel

Inside a Tennessee facility at Oak Ridge National Laboratory, a three-armed robotic platform called MedUSA just laid down enough molten steel wire to produce a three-by-five-foot nuclear pressure vessel. The build ran in a single pass, with three robotic arms working together to deposit metal layer by layer.

Why Wire Arc Printing for Nuclear Parts

Conventional pressure vessels start as large steel forgings. Those forgings require dedicated tooling and long lead times. Domestic forging capacity is limited, and the bottleneck has become a real problem for the nuclear supply chain. Lead times for some custom components now stretch past ten years.

Wire arc additive manufacturing offers a different path. By feeding molten wire through robotic arms and depositing it precisely where the part needs material, the process bypasses forging entirely. The MedUSA platform at ORNL's Manufacturing Demonstration Facility demonstrated that approach at scale, producing a vessel large enough to be relevant to real reactor hardware.

The M2IND Test

The pressure vessel was shown publicly at the Materials and Manufacturing Innovation Days event, where over 350 industry and government leaders gathered at ORNL. The goal of the event was to remove the administrative and technical obstacles that slow advanced manufacturing adoption and turn lab breakthroughs into factory-floor tools.

The vessel was printed in a nuclear-grade steel alloy. Researchers also displayed a glass-fiber polymer model of a spent nuclear fuel impact limiter, produced in collaboration with the University of Maine. That part replaces traditional wood shipping-container designs with something that performs better under impact conditions.

The Certification Problem

Printing the part is one challenge. Getting it approved for real nuclear service is another. Regulators currently require post-production testing, which adds years to qualification timelines.

ORNL and Idaho National Laboratory are now working together to standardize digital qualification methods across facilities. The idea is to use real-time sensors, machine learning, and defect-tracking algorithms during the build to give regulators the data they need to certify parts in months rather than years.

New partnerships with energy companies including SLB and Kairos Power are accelerating the effort. The program's next target: nuclear components weighing 10,000 pounds or more, printed entirely without a forge.

Source: Bytes Europe / VoxelMatters