A modern technique which can be used to make clothes, bikes or even anatomic organs using a wide variety of materials was recently used to build fusion components. The parts have been  constructed especially for JET ’s vessel using 3D printing.

3D printing, also known as Additive Manufacturing (AM), uses successive layers of material to create a three-dimensional object. A computer controls the process. It seems weird to create a rather complex object „at home“ using an off-the-shelf 3D printer but, actually, this technique is a great help when a small number of complex components needs to be produced in a short time.

This tile support assembly for JET was produced using  additive Manufacturing. Pictures: © Copyright protected by United Kingdom Atomic Energy Authority.

This tile support assembly for JET was
produced using additive Manufacturing. Pictures:
© Copyright protected by United
Kingdom Atomic Energy Authority.

Time is money

“The initial drive was to reduce costs and time”, says Valeria Riccardo, Chief Engineer at the Culham Centre for Fusion Energy (CCFE). The two sets of tile support assemblies and the mirror holder have complex features to be aware of. For instance, the tile assemblies need to be able to slot into features of the vessel and then impose a large load on these so as not to slip off during disruptions.

Introducing additive manufacturing

This compact  assembly holds several mirrors close to the plasma. It is used to test how dirty the mirrors get during the plasma experiment in JET’s vessel – information which is needed for ITER’s diagnostic.

This compact assembly holds several mirrors close to the plasma. It is used to test how dirty the mirrors get during the plasma experiment in JET’s vessel – information which is needed for ITER’s diagnostic.

The 3D printed components were installed during JET’s shutdown last year. “The usual method of production would have taken ages. Also, we would lose a lot of material and the costs would have been far too high. So, for the first time, we tried the additive manufacturing with a company”, tells Valeria. And it took the team only four weeks from the idea to the product. The tile assemblies from which each has two AM parts with a combined weight of 1.1 kg and the mirror holder (about 1.2 kg) are made of AM Inconel 718, a special nickel-chromium-based super alloy which withstands harsh conditions. It has been used widely in gas turbines, for example, but not in fusion experiments.

Limited solution for one-of -a-kind pieces

The components were installed in summer of last year. Since then, they have seen a few months of plasma operation without any cause for concern. The ITER mirror assembly will be dismounted at the next shutdown, while the tile support assemblies will be used indefinitely. Depending on how many one-of-a-kind components JET would need to produce again, the engineering team might consider using additive manufacturing as a way of producing the requested bits and pieces. “3D printing takes some time. It is a rather useful way of only creating a small number of components”, adds Valeria.