Structural design aspects of the locking system needed for the next tokamak plasma-facing components against electromagnetic transients

Abstract

A technical key issue during the design of the near-term Tokamak fusion devices (NET and ITER) is related to the structural problems of the needed attachments for the removable internal first-wall components (blanket segments and divertor plates) inside the vacuum vessel in the presence of major plasma disruption events. Both the understanding of the impact of the huge transient electromagnetic forces transmitted onto the vessel from the fastening/guiding support systems and the knowledge of the remote handling operations with related connection/disconnection of the first-wall component supports are involved. Among the various systems proposed as attaching locks, the “Twin-Belt” concept for the inboard blanket region is exposed. It has been developed at the TESLA Laboratory of the JRC-Ispra and has been retained by the NET/ITER Team as one of the options to be studied in detail. The use of such an intermediate toroidal, structurally continuous supporting system (belt bars) provides an independent system of attaching locks between the first-wall region and the vessel.