Despite the best efforts of the R&D on vessel and in-vessel components, inevitably at some time the divertor and blanket may need to be replaced. The blanket is only planned to be replaced once, possibly after 10 years operation, with a breeding blanket in the outboard region, if that proves sensible given tritium supplies and the usefulness of the information to be gained. The divertor is likely to be replaced more often, especially in the earlier operating years, to optimise plasma operation, and to respond to damage caused by pushing the machine performance to find its limits, as well as to inexperience.
As soon as deuterium has been put in the machine, DT reactions will occur and radioactivity levels will be too high at the end of operation for humans to enter. Even during the H-phase of operation, remote handling tools will be essential due to the cramped spaces and large loads to be positioned, and the high and consistent quality needed for attaching these components. It was therefore necessary to demonstrate remota handling capability for these two components, and to learn how long it would take to replace them in reality. Thus two projects were launched: