Fabrication of a double-wall vacuum vessel model of H type steel beam for ITER

A new fabrication method of a vacuum vessel for the fusion experimental reactor (ITER) has been developed. This method is to obtain more desirable fabrication accuracy and easier nondestructive inspections. H type steel beams of 310 mm height and 20 mm thickness have been used as material of a vacuum vessel because of its structural advantages to form a double wall. To make sure of the method and characteristics on fabrication, a full scale half model of a sector was manufactured, and nondestructive examinations and dimension measurements were performed. This paper describes a discussion on the fundamental way to form a double wall vacuum vessel, the procedure of the H type steel vacuum vessel by electron beam welding and the results of experimental model fabrication