ADVANCES IN AM | COVER STORY


process discipline. Even so, extensive data sets are needed to establish confidence considering different failure modes. A second driver for AM development is schedule reliability.


Many of the castings required for low- and medium-criticality components have lead times exceeding nine months, particularly when material specifications are uncommon. Additive routes allow the production of a part once an associated qualified digital model and parameter set exist. Zouari points out that the time reduction is not uniform across all parts but is nonetheless often substantial. “In many cases we see lead times divided by three or four compared with casting,” he says. This time benefit is particularly advantageous during outages. With digital models available, production can be triggered on demand and integrated into outage planning without waiting for casting slots or international logistics. Reverse engineering is another area where additive


manufacturing interacts with technical constraints of the ageing fleet. For a number of BWRs, for example, the original manufacturers no longer exist and technical drawings are incomplete. For these components Framatome will be using scanning and metrology to reconstruct component geometries. Once finalised the digital design can be manufactured either conventionally or through additive processes, which are preferable when the geometry is irregular or when conventional tooling would require custom fixtures. There are also some environmental benefits associated with AM. A recent study on a reactor coolant pump part indicated that the additive route reduced CO₂ emissions by up to 80% when compared with a casting-plus-machining approach. These reductions are derived from the lower volume of raw materials required and the elimination of energy-intensive foundry steps. While environmental considerations are not the primary driver in nuclear component selection, they are increasingly part of corporate EPC requirements.


Building a future for AM in nuclear Despite these advances, additive manufacturing is not expected to replace forging for large primary components. Zouari is explicit on this point. “I cannot imagine replacing forgings and or casting for major reactor pressure components,” he said. The reasons are not purely technical; they include conservatism, long-term irradiation data requirements and the proven behaviour of forged materials under thermal and mechanical loads. Instead, AM processes come to the fore where cost, schedule, geometry or inspection complexity make conventional processes less efficient. Several additively manufactured parts are already installed


in operating PWRs, including plants in France and the United States. These include small components such as pump internals and fuel assembly parts. In December 2024 Framatome installed 3D-printed anti- debris filters for fuel assemblies in the Ringhals 4 reactor, operated by Vattenfall in Sweden. Installed at the base of the fuel assemblies to trap debris in the reactor coolant and protecting fuel rods from damage, the project aims to confirm the integrity of 3D-printed components under real-world conditions as part of a multi-year irradiation programme. The components will undergo annual visual inspections during the plant’s planned outages and reactor refuelling operations. Larger components are also in qualification pipelines but not yet installed in operating reactors at significant


scale. Framatome has also been awarded a contract for serial manufacture of spare parts for an un-named Western utility using additive methods for medium-complexity items. According to Zouari, utilities today are not seeking one-off demonstrations. “They expect us to finalise our standards and provide qualified production routes,” he said. This serves as a clear signal that additive manufacturing is moving from pilot deployment to industrial application. The center in Romans-sur-Isère is structured to support this shift. Each line has controlled atmospheres and audit trails embedded in manufacturing software. Data from sensors, melt pools, thermal histories and machine logs are stored for each build and linked to the unique component identifier as required under nuclear quality assurance programmes. The center also incorporates training functions, and process development bays, allowing new components to shift from R&D to serial production within the same facility. This industrial approach suggests that additive


manufacturing is closing in on a sustained position within nuclear component fabrication targeted at specific applications such as highly complex or schedule-sensitive components. While technical challenges remain with powder quality, porosity control, inspection limitations and heat treatment uniformity all requiring strict control, the tools to manage these issues are now sufficiently developed to support industrial deployment. As the next step in this process, Framatome and


EDF are leading a national project to integrate additive manufacturing new probationary phase rules into RCC-M by 2026/2027, defining how materials, processes, inspection and documentation must be controlled. Similar efforts are underway within ASME committees. Once the standards have been established, additive routes will gain a clearer path into safety-critical applications. As the centre begins serial production, the key measure will be the consistency of mechanical behaviour across batches and the ability to integrate AM parts without introducing new inspection burdens. If these criteria are met, Framatome believes additive manufacturing will become a a key tool in the nuclear manufacturing toolkit, supporting both ageing fleets and future reactor designs. As Zouari concludes: “The goal is to maintain safety while


improving manufacturability. Additive manufacturing allows us to maintain safety levels while offering different routes for manufacturing. The requirements and safety requirement do not change, the processes must meet them.” ■


www.neimagazine.com | March 2026 | 19


Above: WAAM technology was used to manufacture a Framatome pump impeller. Source: MX3D


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