This week, on Tuesday, 6 September, the Indian Domestic Agency ITER India signed the Procurement Arrangement (PA) for the ITER Cryostat, which will be the world's largest high-vacuum chamber, worth approximately EUR 100 million. It is one of the project's largest procurements and thus represents a significant step towards the construction of ITER.

Welded together from thick stainless steel plates measuring between 40 and 180 millimetres, the Cryostat forms the vacuum-tight container surrounding the ITER vacuum vessel and superconducting magnets. The massive structure will have to withstand a vacuum pressure of 1 x 10 -4 Pa; the pump volume is designed for 8,500 m3; and it will have a weight of 3,400 tons. It will have an outer diameter of 28.54 metres and be almost 30 metres tall.

The steel cylinder will have 23 penetrations allowing access inside of the Cryostat for maintenance, as well as over 200 penetrations—some as large as four metres in size—providing access to the vacuum vessel for cooling systems, magnet feeders, auxiliary heating, diagnostics, and the removal of blanket and divertor parts. Large bellows are used between the Cryostat and the vacuum vessel to allow for thermal contraction and expansion in the structures.

Due to size and weight limitations, the Cryostat will be manufactured in segments in India and a sub-assembly of four sections will be prepared at ITER's site workshop. Finally, the four sections will be assembled into the Tokamak pit.

The Cryostat PA was number 59 on ITER's PA list, bringing to 71 percent the amount of in-kind procurements signed to date for the ITER project.