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NUclear COmponents Based on Additive Manufacturing

Periodic Reporting for period 1 - NUCOBAM (NUclear COmponents Based on Additive Manufacturing)

Reporting period: 2020-10-01 to 2022-03-31

Most of the European nuclear power plants in operation were designed and built in the 1970s and 1980s, their components were generally manufactured by conventional metallurgical process. While these process practices have improved over the years in the delivery of high quality products, several reliability issues have emerged. In addition, improvements to the additive manufacturing process over the past 10 years have now made it possible to seriously consider these production processes in the nuclear context.
The objective of “NUclear COmponent Based on Additive Manufacturing” is to develop and qualify this new manufacturing for competitive implementation, efficient, optimized and more robust design of components to enable safe and continuous operation of the NPP and to consider life extension. The cost and availability of electricity are important issues for our society in the years ahead.
The project focuses on two components: the debris filter because its very complicated shape is usually difficult to manufacture using the usual casting and machining, and the valve because subjected to a typical charge of the nuclear power plant where temperature and high pressure level induce corrosion and aging of materials. The project will evaluate new quality control methods to ensure stability, repeatability and reproducibility of processes, resulting in high quality components.

The nuclear qualification of safety-related equipment requires significant investments that are possible in a 4-years project with 13 European partners. The ambitious irradiation program has started on 8 capsules (containing samples) which will be irradiated with neutrons (reactor in Belgium) at different doses with a long-term program (for 18 months). The project is ambitious in terms of the properties of the materials studied (nearly 12) and the post-treatment explored (4 heat treatments), including the variability of the process (4 manufacturers). More than 780 specimens have been manufactured and post-treated and will be tested as part of the project. Changes in material properties will be studied after representative ageing. The specimens will be exposed to heat for 10,000 hours (13 months at a higher temperature than in reality), which is equivalent to a very long plant life.
The development of such a manufacturing process could improve the reliability of the material, reduce the sequence of manufacturing steps, develop new, more efficient tools, improve material performance and develop a new component design.
The strategy for acceptance of metal additive manufacturing in the nuclear sector is to implement directly the qualification of the process and component in nuclear design codes and standards, such as the French nuclear code for Design and Construction Rules for Mechanical Components or American standard. An End User Group was constituted from 15 others industries from 5 others country and with expertises combination on material, mechanical assessment, nuclear industry, and codification to promote our work in the nuclear field.
Obsolescence management remains a technical challenge for European asset owners, because Original Equipment Manufacturers, who were historically subjected to nuclear quality assurance requirements may not be willing to maintain their costly nuclear qualification. Most of those manufacturers have disappeared or have left the nuclear sector.
The project will help to develop in-depth qualifications new manufacturers or components and equipment. Metal additive manufacturing has the unique potential to produce near-to-shape components in a one-step manufacturing process, followed by post-processing steps. This unique approach will simplify the fabrication value chain and make it more reactive and effective for the delivery of unique part.
The project will contribute to create new Additive Manufacturing industry and support employment in Europe.
NUCOBAM is focusing on two Additive Manufacturing Components: the Debris filter and the Valve