Challenges of ITER diagnostic electrical services

Diagnostic electrical services provide the electrical infrastructure to serve diagnostic components installed on the ITER tokamak. This infrastructure is composed of cables, connectors, cable tails, looms, conduits and feedthroughs. The diagnostic services offer as well a shelter for various instrumentations - vacuum vessel (W), blanket and divertor. The diagnostic sensors are located on the inner and outer VV wall, on blanket shield modules, divertor cassettes and in port plugs. They require electrical cabling to extract the measurement and, in some cases, to supply electrical power to the sensors. These cables run from the sensors to feedthroughs on the VV and the port interspace or cryostat. The design and integration of all components that are part of diagnostic electrical services is an important engineering activity that is being challenged by the multiple requirements and constraints which have to be satisfied while at the same time delivering the required diagnostic performance. The positioning of the components must correlate not only with their functional specifications but also with the design of the major ITER components. This is a particular challenge because not all systems have reached the same level of design maturity. This paper outlines the engineering challenges of ITER diagnostics electrical services. The environmental conditions inside the W will have an important impact. Leading risks to these components include poor electrical contact at connectors, the effects of exposure to nuclear irradiation, such as material transmutation, heating, and generation of spurious electrical signals etc., failure due to electromagnetic forces and electrical interference due to the noisy environment. Last but not least are the challenges for confinement and vacuum requirements set up on electrical feedthroughs. It will focus as well on the design and structural assessment of all components, and their requirements. Besides the integration limitations, the loads are the main design driver. (C) 2013 Published by Elsevier B.V.