The final design of the ITER blanket system has been developed and validated, following a meeting of over 80 experts from the ITER Organization, Domestic Agencies and industry in April.

"The development and validation of the final design of the blanket system is a major achievement on our way to deuterium-tritium operation — the main goal of the ITER project," said Rene Raffray, Blanket Integrated Product Team Leader (BIPT) and Section Leader.

The ITER blanket provides the physical boundary for the ultra-hot plasma and contributes to the thermal and nuclear shielding of the vacuum vessel.

The blanket consists of 440 individual modules covering a surface of 600 square meters, with more than 180 design variants depending on the segments’ position inside the vacuum vessel and their functionality. Each module consists of a shield block and first wall, together measuring 1 x 1.5 metres and weighing up to 4.5 tons.

Because of its low plasma-contamination properties, beryllium has been chosen as the element to cover the first wall, the ITER Organization reported in its weekly newsletter.

Other materials used for the blanket system are CuCrZr for the heat sink, ITER-grade steel 316L(N)-IG for the steel structure, Inconel 718 for the bolts and cartridges, an aluminium-bronze alloy for the pads that will buffer the electromechanical loads acting on the segments, and alumina for the insulating layer.

ITER said that the BIPT will now look to address feedback received in the final design review, and can prepare for the procurement arrangements when fabrication is handed over to domestic agencies at the end of this year.

The procurement of the 440 shield blocks is equally shared between China and Korea. The first wall panels will be manufactured by Europe (50%), Russia (40%) and China (10%). Russia will also provide the flexible supports, the key pads and the electrical straps.

The assembly of the blanket is scheduled to begin in May 2021 and is expected to last until August 2022.

Photo: The ITER blanket and first wall are ready to proceed to the manufacturing stage. Courtesy ITER