## Can Wire Arc 3D Printing Replace Forging for Nuclear Pressure Vessels?

Oak Ridge National Laboratory and Idaho National Laboratory printed a nuclear-grade pressure vessel — measuring 3 feet by 5 feet — in July 2026 using wire arc additive manufacturing, the two labs announced August 27. The demonstration is the clearest signal yet that the U.S. national laboratory system is treating forging capacity constraints as a structural threat to nuclear expansion, not a temporary inconvenience.

The vessel was produced at ORNL's Manufacturing Demonstration Facility using the MedUSA platform, which coordinates three robotic arms to melt wire feedstock with electric arcs and build components layer by layer. The material was a steel alloy relevant to nuclear applications, though the specific alloy is not named in the announcement. ORNL and INL describe this as "an early milestone in pressure vessel research" — language that signals the qualification pathway ahead is long, but the process baseline now exists.

For utility procurement teams and SMR developers tracking [first-of-a-kind (FOAK)](https://smrintel.com/glossary/foak) cost drivers, this matters: pressure vessel forging is one of the hardest supply-chain constraints to solve at speed, and wire arc additive manufacturing offers a domestically scalable alternative.

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## The Forging Bottleneck Driving This Research

Nuclear pressure vessels are among the most demanding manufactured components in any energy system. They must maintain structural integrity under sustained high pressure and radiation, which is why traditional production relies on large-scale forging — a process that requires specialized heavy presses, trained operators, and extended lead times.

As U.S. nuclear ambitions have grown, so has pressure on a forging supply base that was not sized for an expansion cycle. This isn't a new problem: the nuclear industry flagged limited domestic forging capacity as a constraint during the original Generation III+ build-out discussions, and it has only become more acute as multiple SMR developers simultaneously target deployment in the late 2020s and early 2030s.

Wire arc additive manufacturing sidesteps the forging bottleneck by building large parts incrementally from wire feedstock using robotic welding systems. According to the joint ORNL-INL announcement, the technique "can be used to print large parts and offers speed and flexibility that forging does not." That flexibility — the ability to print geometry that forges cannot easily produce, and to do so without dedicated tooling — is the core industrial value proposition.

The challenge, always, is qualification. ASME codes and NRC licensing frameworks were written around forged and wrought materials with decades of empirical performance data behind them. Demonstrating that additive manufacturing can meet equivalent structural and material standards — including toughness, fracture behavior, and weld zone integrity — is precisely the work that this ORNL-INL collaboration is designed to address.

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## AI Integration and Real-Time Process Monitoring

The collaboration's technical architecture goes beyond printing. INL is contributing expertise in AI and data science to enable real-time performance evaluation during fabrication — what INL group lead for advanced manufacturing Jorgen Rufner described as evaluating "a part's performance in real time, while it's being printed, instead of waiting for post-production testing."

This is a meaningful shift in quality assurance philosophy. Conventional non-destructive examination happens after a component is complete, which means defects discovered late can require scrapping or reworking expensive, partially-finished hardware. Embedding AI-driven process monitoring into the build itself — using sensor data to infer material state layer by layer — could compress the defect detection loop dramatically and build the digital evidence base that regulators will eventually need to see for code qualification.

The same MedUSA printer and material used in the pressure vessel demonstration was previously used to manufacture neutron sensor brackets for Antares's Mark-0 microreactor, which achieved zero-power fueled [criticality](https://smrintel.com/glossary/criticality) at INL in June 2026. That application-to-application continuity is notable: ORNL is building a track record of additive manufacturing outputs that have actually entered nuclear service, not just remained as laboratory specimens.

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## Precedent: The Transformational Challenge Reactor

ORNL's engagement with AI-integrated additive manufacturing in nuclear applications predates this collaboration. The lab led the Transformational Challenge Reactor (TCR) project, launched by the DOE Office of Nuclear Energy in 2019, which aimed to use advanced manufacturing to produce an operating nuclear microreactor by 2023. The TCR did not ultimately complete a reactor demonstration, but its research outputs — including reactor design methodologies and materials testing work enabled by rapid prototyping — were documented in a special issue of *Nuclear Science and Engineering*.

The TCR experience is instructive for calibrating expectations here. Demonstrating a manufacturing process and qualifying it for licensed nuclear service are separated by years of testing, code case development, and regulatory engagement. The July pressure vessel print is a process proof-of-concept; the path to a commercially procurable, NRC-acceptable additive-manufactured pressure vessel runs through ASME Section III code cases and extensive material property databases that do not yet fully exist for wire arc deposits.

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## Industry Implications

For SMR developers, the ORNL-INL program represents potential relief from one of the more intractable hardware bottlenecks in their deployment schedules. If wire arc additive manufacturing can be qualified to nuclear pressure vessel standards, it opens the door to a domestic manufacturing pathway that is not capacity-constrained by the handful of heavy forges currently capable of nuclear-grade work.

For the supply chain more broadly, the emphasis on "domestic" in ORNL associate laboratory director Robert Wagner's statement — "strengthen the domestic supply chains essential to America's energy future" — reflects a policy posture that has accelerated across DOE programs. Reducing dependence on non-domestic forging for nuclear-critical components is now framed explicitly as an energy security issue, not just an industrial competitiveness question.

The chemical processing industry is also named as a target application, which broadens the commercial case and could help defray qualification costs across a wider customer base.

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## Key Takeaways

- ORNL and INL printed a 3-ft-by-5-ft nuclear pressure vessel in July 2026 using the MedUSA wire arc additive manufacturing platform — an early process milestone, not a qualified product.
- The collaboration integrates AI-driven real-time process monitoring, developed by INL, to evaluate part performance during printing rather than relying solely on post-production inspection.
- Limited domestic forging capacity is the explicit supply-chain problem this research targets, directly relevant to SMR deployment timelines.
- The same ORNL printer and material were used to produce neutron sensor brackets for Antares's Mark-0 microreactor, which achieved zero-power criticality at INL in June 2026.
- Full qualification for NRC-licensed nuclear service requires ASME code case development and extensive materials testing that remain ahead — the July demonstration establishes a process baseline, not a finished pathway.
- ORNL's previous Transformational Challenge Reactor program (launched 2019) did not complete a reactor demonstration, a precedent worth tracking as expectations around additive nuclear manufacturing are set.

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## Frequently Asked Questions

**What did ORNL and INL actually demonstrate in July 2026?**
Scientists at ORNL's Manufacturing Demonstration Facility used the MedUSA wire arc additive manufacturing platform to print a nuclear pressure vessel measuring 3 feet by 5 feet from a steel alloy relevant to nuclear applications. Both labs describe it as an early milestone in pressure vessel research — a process proof-of-concept rather than a commercially ready or NRC-qualified component.

**What is wire arc additive manufacturing and how does it differ from forging?**
Wire arc additive manufacturing uses a robotic welding arm and wire feedstock to build components layer by layer by melting the wire with electric arcs. Forging shapes metal under compressive force using large presses, producing dense, work-hardened material with well-characterized properties. Wire arc printing offers more geometric flexibility and does not require dedicated tooling or large-capacity presses, but its material properties differ from forged equivalents and must be independently qualified for nuclear code compliance.

**Why does forging capacity constrain U.S. nuclear expansion?**
Nuclear pressure vessels require exceptionally large, specialized forging equipment and highly trained operators. The domestic supply base for nuclear-grade forgings is limited, and as multiple reactor developers simultaneously pursue deployment, competition for available forging slots can extend procurement timelines significantly. Wire arc additive manufacturing is being evaluated as a domestic alternative that could scale without the same capital and facility constraints.

**How does AI fit into this pressure vessel manufacturing process?**
INL is integrating AI and data science with the printing process to evaluate a component's structural performance in real time as it is being built, rather than relying exclusively on post-production non-destructive examination. This approach could identify process deviations earlier, reduce scrap risk, and help build the data record regulators and code bodies will require for formal qualification of additively manufactured nuclear components.

**What regulatory steps are needed before 3D-printed pressure vessels can be used in licensed reactors?**
Wire arc additive manufacturing of nuclear pressure vessels would need to be incorporated into ASME Boiler and Pressure Vessel Code Section III through code cases supported by extensive materials testing data — tensile properties, fracture toughness, fatigue behavior, and irradiation performance, among others. NRC review and acceptance of those code cases would also be required. This qualification process typically takes years and requires collaboration between national labs, industry, and standards bodies.