The US Home Team is coordinating the manufacture and assembly of a full-scale, half section, prototype ITER divertor cassette. This cassette will integrate actively-cooled Plasma Facing Components (PFCs) supplied by all four ITER parties on to a large (>20 tonne) stainless steel body structure. The prototype half-cassette PFCs include an inner vertical target, short dump and wing manufactured by the JA team; an outer vertical target and wing manufactured by the EU team; two gas-box liners manufactured by the RF team; and a central dome assembly manufactured by the US. The body is designed to support and accurately position the PFCs, distribute cooling water to the PFCs and itself, and provide shielding for the vacuum vessel and magnets. The cassette is also designed to withstand electromagnetic loads and provide for PFC replacement in a separate hot cell facility. Sixty cassette assemblies are used to form the divertor.

The cassette structure is designed to be a full-life component, accommodating several sets of PFCs over the life of ITER. As a result, the divertor cassettes are modular structures to promote remote installation and removal from the vacuum chamber during maintenance operations, as well as straight-forward, side-access for removal and replacement of the PFCs. There are five sets of mirror-image PFC assemblies that are attached to the body through structural keys that are locked into slots machined in the body and the rear surface of the PFCs. The keys are designed to accommodate both electromagnetic loads and differential thermal expansion to avoid stress build-up in the PFCs. Coolant is supplied through pipe-stub interfaces with the body that are remotely cut and re-welded using standard techniques.

The paper will review design integration work and manufacturing / assembly plans for the prototype divertor cassette project. It will highlight tolerancing and interface issues, assembly tooling / sequences, and design concept evolution based on manufacturability and cost considerations. Produciblity and modularity are key design drivers for the ITER divertor hardware since it must be affordable yet satisfy performance and maintenance requirements.

* Work supported by US DOE under Contract AC-3013 with Sandia National Laboratories.