HELCZA is ready to test more in-vessel components for ITER

In large fusion reactors like ITER, the plasma will unleash extreme heat onto the shell of the device. European in-vessel components like the first wall panels and the divertor inner targets will be on the front line of this thermal bombardment. The divertor surfaces, for instance, will receive 10-20 MW per m² – more than a spacecraft re-entering Earth. Therefore, before installing them in ITER, these armoured components must prove they can cope with temperatures of such intensity for the length of operations. High heat flux testing is an essential checkpoint. For manufacturers, it determines whether the fabrication process can continue or it needs to be revisited.

However, there are few facilities worldwide able to replicate ITER’s powerful heat flux. One of them is HELCZA, hosted by Research Centre Řež (CVŘ) in Plzeň, Czechia. This state-of-the-art testbed was set up by Fusion for Energy (F4E), with the support of EU funds and the Czech Ministry of Education, Youth and Sports. It was a strategic investment to strengthen Europe’s capacity to delivery key fusion components by testing them on its own soil.

HELCZA’s first clients were the first wall panels of ITER. F4E is responsible for 215 of the blocks that will face the plasma and protect the vacuum vessel. From 2021 to 2024, HELCZA tested three full-scale prototypes manufactured by different European suppliers, plus two partial-scale ones. In a nutshell, the beryllium-covered panels were placed inside a vacuum chamber and shot with a beam of accelerated electrons. For each of them, HELCZA ran 9000 cycles at 2 MW. The persistence harvested results: “The long campaigns were critical to check the performance of the materials, joints or cooling systems. The skill and dedication of HELCZA’s team helped Europe to validate some of the methods of fabrication and spot improvements. Despite the change in armour material, this knowledge bolsters our confidence ahead of series production,” describes Robin Shuff, Technical Officer for F4E.

After this success, F4E decided to make further use of the facility. This time for a different European component: the Inner Vertical Targets (IVT). They are part of the divertor, resembling a ring-shaped ashtray at the bottom of the device.  A team of seven technicians worked non-stop for six months to decontaminate the main room from toxic residues of beryllium. In parallel, F4E and CVŘ prepared all the test specifications with ITER Organization and re-engineered the machines to accommodate the IVT samples.

“In less than a year, we managed to decontaminate and qualify HELCZA for the IVT, a component shielded with tungsten. We are ready to start testing the plasma facing units, a key step for our suppliers to move forward with series production,” explains José Luis Capón, Technical Officer at F4E. Testing will start after summer, first with samples from Research Instruments, followed by those from Alsymex.

Both cases highlight HELCZA’s return on investment for Europe. “It’s an outstanding facility: it has the latest equipment, such as advanced remote control systems and diagnostics, run by expert personnel capable of solving any technical issue,” claims Pierre Gavila, In-Vessel Project Manager at F4E. The testbed was purpose-built for ITER, but its value can go beyond the project. “High heat flux test facilities are an indispensable asset to qualify plasma-facing components of a fusion reactor. HELCZA will keep helping ITER, and in the future DEMO, by testing some of their large tungsten components,” explains Richard Jílek, HELCZA Team Leader for CVŘ. “We can also contribute to other fields beyond fusion such as the aerospace industry and, in general, to the development of advanced materials,” he adds.