IN Brief:
- Framatome has opened a €30m industrial pilot at Paimboeuf for chromium-coated nuclear fuel cladding.
- The physical vapour coating process is intended to improve zirconium alloy cladding performance under demanding conditions.
- The line is designed for more than 100,000 tubes a year, with qualification targeted by end-2026.
Framatome has inaugurated a €30 million industrial pilot at its Paimboeuf manufacturing site in western France to apply chromium coatings to zirconium alloy tubes used in nuclear fuel assemblies. The facility forms part of the company’s PROtect Enhanced Accident Tolerant Fuel programme and is designed to demonstrate a coating process at conditions representative of future serial manufacture, rather than remain a laboratory-scale treatment.
The new installation is designed to produce more than 100,000 chromium-coated tubes annually, although Framatome says that capacity may evolve as the technology develops. Industrial qualification of the process is scheduled for the end of 2026, followed by a target to begin production in early 2027. Consistency across the full length of each coated tube will be central to evaluating the process, as the protective layer must survive subsequent fuel manufacturing steps and remain suitable for reactor service. Those milestones concern the manufacturing operation; qualification and individual reactor fuel loading decisions remain separate parts of the route towards broader deployment.
Zirconium alloy cladding forms a physical barrier around the ceramic uranium fuel pellets in a reactor fuel rod. In normal service it must retain its integrity through prolonged exposure to coolant, high temperature, radiation and changes in internal and external pressure. Its behaviour also becomes particularly important during an accident involving reduced cooling. Framatome’s approach deposits a chromium layer onto the surface of the zirconium alloy rather than replacing the underlying tube with an entirely different structural material.
The coating is applied using a physical vapour process, which deposits chromium onto the tube surface under controlled manufacturing conditions. The coated cladding retains its zirconium alloy substrate while adding an external layer intended to resist oxidation. Under severe loss-of-cooling conditions, the coating can slow oxidation reactions involving the cladding and thereby reduce hydrogen formation; improved high-temperature mechanical performance is another objective of the PROtect programme. The coating must retain the necessary properties throughout manufacture and reactor operation.
Industrialising that process requires coating quality and repeatability across large numbers of long, relatively thin tubes. Consistent surface preparation, deposition conditions and inspection procedures are essential if manufacturing results are to remain comparable between production batches. The Paimboeuf pilot will be used to establish process robustness under conditions approaching serial production. With capacity measured in six figures of tubes each year, the challenge extends from laboratory coating performance to controlled manufacture at fuel supply chain scale.
The PROtect Enhanced Accident Tolerant Fuel technology was developed with the French Alternative Energies and Atomic Energy Commission. Alongside chromium-coated cladding, it can use uranium fuel pellets enhanced with chromium oxide where requested by reactor operators. The coating and pellet developments are related but distinct elements, and customers may select configurations according to their licensing and fuel performance requirements. Their introduction into operating reactors depends on the applicable testing, qualification and regulatory arrangements.
Framatome has accumulated more than a decade of research and operational experience with the technology, including irradiation in six reactors globally. First fuel-rod irradiations began in 2019 at Gösgen in Switzerland and Vogtle in the United States; a full PROtect fuel assembly was loaded at Calvert Cliffs in 2021. Four lead fuel assemblies entered EDF’s French pressurised water reactors from 2023. At Vogtle, PROtect fuel rods completed a third 18-month cycle in 2024, while rods at Gösgen operated at burnup above 60GWd per tonne of uranium. Those irradiation results inform the transition to repeatable industrial coating.
The Paimboeuf site already produces zirconium alloy components used in fuel assemblies supplied to nuclear operators in France and overseas. Adding chromium coating to that established manufacturing chain brings the surface treatment process closer to the tube manufacturing operation. This provides a basis for examining production throughput, material handling, quality assurance and the transfer of coated tubes to later stages of fuel assembly manufacture without treating each step as a separate experimental exercise.
The programme has received support through France Relance and the US Department of Energy’s accident-tolerant fuel work. The evidence from irradiated rods and assemblies feeds into process qualification at Paimboeuf, where the coating must be applied repeatedly to production volumes rather than selected experimental samples. Quality assurance will have to establish that the industrial route delivers the required surface characteristics consistently, alongside the material and in-reactor performance already evaluated during testing.
Framatome is targeting industrial process qualification by the end of 2026 and the start of production in early 2027. The new pilot’s designed capacity exceeds 100,000 tubes annually, but the actual output and broader use of coated cladding will follow the qualification programme and individual operators’ fuel deployment arrangements. That schedule makes manufacturing repeatability the immediate test for a technology already exposed to operating reactor conditions.
