COVER STORY | ADVANCES IN AM
● Wire-arc additive manufacturing (WAAM) addresses components on a significantly larger scale. “We are able to make parts more than six metres in diameter and up to 25 tonnes in weight,” Zouari says. WAAM offers deposition rates that can exceed several kilograms per hour, which makes it suitable for large structures that would otherwise require welding of multiple pieces. As with all welding processes, one of the key challenges with WAAM is to control heat input sufficiently to avoid excessive residual stresses and unfavourable grain growth. Framatome’s development work has focused on the coupling of chemical composition, deposition paths with interpass thermal control and with subsequent heat treatment sequences. The aim is to achieve homogeneous mechanical properties through the thickness of the deposited material. To address this Framatome implements in-situ monitoring of arc stability and bead geometry. These data feed directly into qualification materials submitted to utilities and regulators.
● Cold spray is also featured at Romans, primarily for fuel- related components. The method involves accelerating metallic powder particles at high velocity onto a substrate, bonding them through plastic deformation without melting. Because no melting occurs, oxidation is minimal and materials sensitive to thermal gradients can be deposited without altering bulk properties. Framatome already has established serial production for specific fuel components using cold spray. The cold spray line at Romans-sur-Isère supports higher throughput and improved process control. The design of the production bays reflects this, with powder handling, substrate preparation and post-processing fully separated to prevent cross-contamination.
Below: Framatome’s 3D-printed ATRIUM 11 upper tie plate grid was deployed at the Forsmark Nuclear Power Plant in Sweden.
● Hot isostatic pressing (HIP) is another key technology that Framatome’s additive manufacturing center engineers are outsourcing but with a dictated homemade process. In Framatome’s case, the HIP route is used primarily to produce monolithic near-net-shape blocks or pipe bodies that eliminate welds. Zouari highlights the relevance for T-connections and similar geometries. “If a forged part is made in multiple pieces, welds are unavoidable. In some cases, these welds can be complex to control and hencea single body, is prefered so producing the shape by HIP becomes an alternative,” he says. HIP processing can generate full density components with the required dimensional accuracy. For nuclear piping systems, the advantage is the removal of welds in locations that complicate inspection or fall under high-scrutiny classification boundaries.
Additive processes including directed energy deposition (DED), plasma transferred arc welding and binder jetting are under evaluation for potential integration but are not yet deployed in serial production. Framatome’s approach has been to industrialise only those technologies where mechanical properties, inspection methods and surface finishing routes are fully characterised. Zouari describes the process as incremental. “We do not mix technologies until we know exactly the impact of each one,” he says. Nevertheless, Framatome anticipates that HIP and DED and/or L-PBF could eventually form hybrid manufacturing techniques, with HIP used to stabilise microstructures in components built by powder or wire processes when extreme density or defect tolerance is required. Across these technologies, the technical priority is
repeatability even though additive manufacturing introduces multiple process variables such as laser power, scan speed and hatch spacing for powder-bed systems or wire feed rate, torch velocity and shielding gas quality for WAAM, for example. Once qualified, the process becomes a “special process”
under RCC-M or ASME rules, requiring manufacturers to demonstrate control rather than rely on post-production inspection alone. This is why Framatome has invested in developing its own material specifications and parameter sets. As Zouari explains: “Material qualification is about the entire chain: powder or wire quality, build parameters, thermal history and heat treatment. If one link changes, the properties change.”
Inspection and non-destructive examination remain
central to qualification. Additive routes often produce internal features, for example, integrated manifolds or lattice structures, that can be difficult to inspect using conventional Ultrasonic testing (UT) and Radiographic testing (RT) methods. In WAAM components, UT inspection is more straightforward but requires calibration using blocks built with the same deposition parameters. The Romans-sur-Isère centre includes dedicated Non-destructive Evaluation (NDE) suites for UT and CT validation, allowing process parameters to be linked directly to inspection procedures.
The AM advantage One of the key technical drivers behind Framatome’s additive program is the reduction of welds in components where weld quality dominates inspection complexity. For example, T-junctions in primary circuit piping involve multiple welds, each requiring its own volumetric inspection and associated documentation. Producing these geometries in a single piece, either through HIP or WAAM followed by machining, removes potential defect sites and reduces the lifecycle inspection burden. Regulators have also shown interest in this route, with Zouari noting that recent exchanges with the French nuclear regulator had confirmed that “the regulatory framework is not a barrier and that component 3D printed shall reach at least the same safety demonstration that component from classical manufacturing routes” and for the deployment of these technologies. This regulator perspective is crucial. While additive manufacturing is often portrayed as a disruptive technology, nuclear licensing environments require stability, traceability and replicability. The technical challenge is therefore not to demonstrate the ability to create components with novel geometries but to demonstrate that AM materials conform to well-understood mechanical behaviours. Framatome believes that additive processes do not require new metallurgy but rather tighter
18 | March 2026 |
www.neimagazine.com
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