ORNL and A.J. Tuck Use 3D Printed Mandrels to Build Leak-Free Nuclear Parts

A New Hybrid Route Around the Forging Bottleneck

Oak Ridge National Laboratory and A.J. Tuck Company have developed a hybrid manufacturing process that uses a 3D printed mandrel as the starting point for leak-free metal components. The method combines additive manufacturing, electroforming, and hot isostatic pressing (HIP) to make containers and parts that would normally depend on scarce domestic forging capacity.

The two organizations announced the work during Materials and Manufacturing Innovation Days at ORNL's Manufacturing Demonstration Facility in August 2026. A cooperative research and development agreement led to a licensing agreement shortly after, suggesting both sides see commercial potential.

The concept is straightforward once you look past the individual steps. A mandrel is printed in the geometry needed to define the inside of a hollow component. Electroforming deposits a dense metal skin around the printed shape. Hot isostatic pressing then fuses the structure into a solid, leak-free part. The printed mandrel itself does not survive as a separate piece, but it acts as a reusable core that replaces the expensive tooling normally required for forgings or castings.

The target market is advanced nuclear reactors, small modular reactors, and related energy systems. These programs need pressure vessels, valves, turbine components, and other large metal parts that must be leak-free under demanding conditions. Domestic forging capacity for such parts has been shrinking, and much of the remaining capability sits outside the U.S. supply chain. The ORNL approach offers a way to produce similar parts without relying on that concentrated infrastructure.

Early Results Look Promising

In the first phase of the project, the team produced five leak-free cylindrical HIP cans, each six inches tall and four inches in diameter. Using one of those cans, they fabricated a solid nickel component weighing 15.7 pounds. That is not a full-scale reactor part, but it is a convincing proof that the process can create dense, leak-free structures from a printed starting point.

The second phase is already underway and will target a more complex geometry. The team is considering an impeller or a valve, both of which are relevant to nuclear energy systems. These shapes would test whether the printed mandrel approach can handle internal passages, thin walls, and curved surfaces without introducing defects during electroforming or HIP.

A.J. Tuck Company is not a household name in additive manufacturing, but it brings decades of electroforming expertise. Dara Williams, the company's president, described the partnership as a way to apply that capability to a new domain. ORNL researchers are contributing the additive manufacturing side, along with access to equipment and characterization labs that most private companies cannot match.

Why This Matters for the Nuclear Supply Chain

The energy sector has been looking for domestic alternatives to large forgings for years. Reactor pressure vessels, steam generator components, and valves have historically been produced by a small number of forges around the world. Lead times can stretch into years, and geopolitical risk adds uncertainty. A process that can print the hard part of the geometry and then densify it with well-understood conventional steps could shorten those lead times and reduce dependence on foreign suppliers.

The hybrid nature of the process is important. Pure additive manufacturing can make complex shapes, but qualifying printed metal parts for nuclear service takes years. Pure electroforming can make thin-walled, precise shapes, but it is not ideal for heavy structural components. HIP is widely used to densify castings and additive parts, but it needs a sealed container to apply pressure effectively. Combining all three methods lets each step cover the weaknesses of the others.

ORNL and A.J. Tuck have filed an invention disclosure and a provisional patent covering the approach. That intellectual property could become valuable if the nuclear sector continues its current growth trajectory and if domestic manufacturing remains a policy priority.

The Bigger Picture

This is one of several ORNL-led efforts aimed at the nuclear supply gap. Separate projects are exploring AI-guided wire arc additive manufacturing and new aluminum alloys for high-temperature service. The common thread is a focus on practical manufacturing methods that can produce real parts, not just laboratory demonstrations.

The 3D printed mandrel approach is unlikely to replace large forgings immediately. Qualification timelines in nuclear energy are measured in years, and regulators will want extensive test data before approving any new process. But the early results from the ORNL and A.J. Tuck team suggest a credible path forward, and that is more than can be said for many additive manufacturing concepts that never leave the lab.