European factories in motion for ITER first wall panels

In the heart of the ITER device, temperatures will be ten times hotter than those in the core of the sun. A stainless-steel wall will face the plasma’s extreme heat and radiation during the lifetime of the experiment. The ITER Blanket will be formed by 440 modules, covering the inner 600 m² of the Vacuum Vessel. They each measure 1 x 1.5 m and consist of two parts. On the surface, the first wall panels will be the main protective barrier thanks to an armour of tungsten. Beneath them, thicker stainless-steel blocks will act as shields to the high-energy neutrons escaping the fusion reaction. Cooling water will run through them via special pipes to remove the heat, which in future power plants will be used to generate electricity.

Europe is responsible for providing 212 first wall panels, plus spares. These are first-of-a-kind components with very demanding requirements. They must withstand the intense heat and neutron stream of ITER and survive thousands of heating and cooling cycles without cracking or deforming. Over the last decade, Fusion for Energy (F4E) has collaborated with different companies to develop and test solutions, from partial mock-ups to full-scale prototypes. The efforts have been fruitful, sharpening the design and building up industrial know-how.

In 2021, F4E signed two contracts to produce series panels: one with Alsymex, and another with Fusion Business Leadership (FBL), a consortium of Leading and Empresarios Agrupados. So far, each of them has been entrusted with 27 panels, plus three pre-series units. Competition between the two will re-open in future calls to allocate the rest. “Working with two suppliers gives us different fabrication pathways, we draw more lessons and foster competition and innovation,” explains Stefano Banetta, F4E Programme Manager.

The companies started with the pre-series panels to validate and qualify the manufacturing processes. Next, the pre-series units began a thorough sequence of acceptance tests. The teams assess their resistance to pressure and heat, verify dimensions, examine joints, and check for leaks. This month, the first unit from each supplier completed a full set of tests.

What is the next challenge? “Our focus is on scaling up the production. Building the panels in series is very different from developing single prototypes. Industrialising the process requires bespoke tools, advanced design and material solutions,” describes Banetta. Thanks to F4E’s investment, the workshops of Alsymex in Tarbes (France) and Leading in Cantabria (Spain) have been converted into specialised factories. They are equipped with machines for milling or drilling, assembly clean rooms and areas for testing, including metrology or ultrasonic inspections and hot helium leak tests.

Both series production lines are up and running. For now, the suppliers are centred on shaping the structure of the panels, made of a stainless steel-copper alloy, following the steps validated with the pre-series. The armour made of tungsten tiles will be joined onto them at a later stage. The procurement of this material, a novelty of the revised ITER baseline, will be critical for Europe in order to deliver the 212 first wall panels.

“FBL’s progress in manufacturing the first wall panels is the result of our commitment with the project and close collaboration with F4E and ITER Organization. Our consortium has grown into a unique high-precision manufacturing company, with the strength to face the challenges of fusion technology” say Maite Domínguez and Marcos Pérez, Members of the FBL Steering Committee.

“In the past years, and with the continuous support of F4E, we have solved many of the challenges to industrialize and qualify manufacturing and test processes. We have set up a large and modern production line, which is now Alsymex’s flagship factory. All our team is proud of the results and ready for the next stage, with the ramp-up of production and supporting F4E’s qualification of the tungsten armour,” expresses Olivier Huet, Alsymex CEO.