International teamwork paves the way for ITER Test Blanket Modules

ITER will help us solve many of the complex physics and technology challenges to make fusion a viable energy source. A major one is tritium breeding, key for the fuel self-sufficiency of future power plants. Tritium is a rare hydrogen isotope that fuses with deuterium, releasing large amounts of energy. To regenerate this scarce fuel, future power plants will rely on the breeding blanket, an in-vessel component where powerful neutrons from fusion will hit lithium to create new tritium.

However, engineering this process in the heart of a reactor is no small feat. In ITER, experts will study four prototypes, called the Test Blanket Modules (TBM), designed by different ITER parties. Europe is working on two TBM concepts: a water-cooled lead lithium and a helium-cooled ceramic pebble bed, the latter co-developed with Korea.

Currently, both designs keep gaining ground ahead of the Preliminary Design Review, planned in 2026. Fusion for Energy (F4E) is working hand-in-hand with ITER Korea, as well as ITER Organization (IO), responsible for the integration, operation and safety of the TBM. The three teams met recently at the ITER site for a workshop to assess the readiness of the designs.

The meeting went through an extensive four-day agenda, which reflected the breadth of requirements the TBM must cover. In preparation for it, both agencies had submitted close to 40 documents to IO. These included design justifications, manufacturability studies and engineering analysis carried out by specialised suppliers and laboratories.

“The TBM are at the cutting edge of nuclear technology, with a huge volume of R&D behind, in areas like advanced materials. ITER is offering a one-of-a-kind opportunity to further develop and, later, test them. That’s why we are so thorough in their design, integrating the knowledge from European fusion laboratories, F4E and international partners,” explains Francesca Fantini, TBM Programme Manager at F4E.

Teamwork is key in designing such complex first-of-a-kind equipment. “The workshop was an excellent example of the effective international collaboration between Korea, Europe and ITER Organization. This constructive dialogue helps us plan the way ahead and solve design issues, all whilst optimising our resources,” claims Mu-Young Ahn, TBM Technology Team Leader at ITER Korea.

“The productive discussions have been a unique opportunity to consolidate a joint plan to tackle key challenges for the TBM technologies and the integration in ITER. We enjoyed productive exchanges on the TBM lifecycle, from design to manufacturing, installation and operation.” says Rossella Rotella, Tritium Breeding Blankets Project Leader at IO. Her team is developing the infrastructure to host the TBM and leading the working group on integration safety and preparation of operation, two crucial factors for the TBM. “We are working intensively to develop solutions compliant with the stringent safety requirements and operational performances. In this challenging context, close cooperation and technical expertise are our best assets to succeed”, she adds

The teams left with a clear list of tasks, a boosted team spirit and the confidence that the design is on the right track. Next year’s “gate review”, as engineers call it, will be an important checkpoint to confirm the maturity of the design. “Despite the numerous technical challenges, we’re making steady progress and accumulating great know-how in the process. The ITER TBM bring Europe invaluable learnings for the breeding blanket of DEMO and the next generation of fusion reactors,” concludes F4E’s Francesca Fantini.