ITER: Design overview

To demonstrate the scientific and technological feasibility of fusion is the programmatic objective of ITER. The ITER plasma, therefore, has to achieve high power gain and a stationary plasma condition, namely an ignited burn lasting several hundred seconds. Commercial reactor requirements suggest the inclusion of steady state as an ultimate goal. Such a device is a unique engineering test bed, in particular for components interacting directly with the plasma such as the first wall, divertor and blanket. These tests would have reactor relevance since the burn pulse can be extended beyond 1000 seconds maintaining a neutron wall loading of around 1 MW/m2 and achieve a neutron fluence of up to 1 MWa/m2. In the investigation of the design concepts, an essential role is played by the R and D in physics and technology needed to support each option: the extent of the extrapolation from existing and anticipated databases, the reproducibility scale of a component and of its operating conditions and the reliability of the R and D planning are all important elements which have been taken into consideration. The design work conducted during the Conceptual Design Activity (CDA) has reached its main objective, namely to assess the feasibility of the apparatus and to establish a sound technical basis to proceed with the final engineering design. A coherent single conceptual design of the apparatus has been developed. It elucidates the operation and the integration issues and is complemented by an analysis of the design options, including the required R and D of the most critical components. (author). 9 refs