Europe will manufacture 60 divertor cassettes

This is a place that will feel very much like the surface of the Sun. When deuterium-tritium operation begins, the ITER divertor will carry a heat load twenty thousand times higher than that of a hot July day in Provence.

As if that wasn't enough, the divertor structure will also have to withstand tremendous magnetic forces that will press and pull with a force on the order of one hundred tonnes.

An essential component of the ITER machine, the divertor is also one of the most challenging to build, assemble and install.

 

The ITER divertor acts as the Tokamak's exhaust system, running toroidally along the bottom of the vacuum vessel, extracting helium ash from the burning plasma. It is split into 54 cassettes, each containing a plasma-facing "dome", inner and outer "targets," and a number of diagnostic systems. There are 19 variances in the diagnostics arrangements and as many integration issues ...

Each nine-tonne cassette will be installed inside the vacuum vessel through remote handling operations. The highly complex and delicate installation sequences are being demonstrated and validated at the ITER Divertor Test Platform Facility in Tampere, Finland.

"The key challenges in this Procurement Arrangement are: one, the manufacturing tolerance to meet the interfaces (on the order of a fraction of a millimetre); and two, the assembly sequence of the different divertor components," explains Mario Merola, head of the Internal Components Division. "Planning and coordination will be paramount."

Following the production of a full-scale prototype for assembly trials, series production should begin in 2015. The present schedule plans for the installation of all 54 cassettes beginning in 2021 during the second phase of ITER assembly; the divertor will only be needed when hydrogen-helium operation begins in 2022.