Reliability, availability, and quality assurance considerations for fusion components

Applying the principle of toroidal magnetic confinement, future fusion machines will feature the combination of nuclear-thermal components supplied from the outside via penetrations through cryogenic-electromagnetic components. These penetrations, together with the toroidal segmentation, require to seal - in comparison to fission reactors - more media and more spaces from each other under more stringent conditions with respect to radiation, vacuum, remote handling, tritium, and cryogenics. Therefore, fusion reactor components are required to have higher reliability than fission reactor components. However, for fusion reactor components basically the same single design elements like, for instance, welds, pipes and plates will be applied as in fission reactors. As fusion components will be manufactured by the same type of industry which in the past built fission reactors with nuclear grade quality, the reliability of the design elements in principle can hardly be expected to be far better than in fission reactors. Therefore, it is the arrangement of these elements, i.e. the design of the components, which has to be such that their failures have nevertheless acceptably benign consequences