Evolving targets for DEMO: Implications for materials development

Current reference fusion development scenarios assume the sequential achievement of key milestones. Firstly, the qualification of the plasma physics basis in ITER, together with the qualification of materials for in-vessel components in IFMIF. Secondly, the qualification of components and processes in DEMO. However, the circumstances, within which fusion development planning is undertaken, are changing, and it is becoming reasonable to plan on the assumption that within 20 years ITER and IFMIF will have been successful and the world will be eager for clean, secure energy supplies. This motivates supplementing the reference scenario with the consideration of reduced targets for the economic performance of a first generation of fusion power plants that could be deployed as early as possible, and so reduced targets for the technical performance of early DEMOs. The implications of the reference scenario and variants for fusion materials development are considerable, and these are discussed in this paper.