Main Features of ITER Vacuum Vessel and Approach to Code Application

The ITER Vacuum Vessel (VV) is a complex torus-shaped configuration with a double-walled structure and the main function is to provide a high degree of vacuum for DT operation and form an enclosure for containing radioactive materials. Such structural uniqueness requires quite different technologies and implementations from the existing plant, so that technical rules are to be evolved on design, fabrication and examination for assuring its structural reliability. A new code concept, namely system-based code for integrity, has been developed so as to optimize the total reliability to be attained for ITER operation, considering unique structural features and safety attractiveness. This paper describes structural features of the ITER VV from code standpoint and basic approach to code application, together with on-going research activities for supporting the code development. (authors)