Results from ITER vacuum vessel sector manufacturing development in Europe

This paper describes the results from several R&D tasks carried out in Europe to improve the prospects for manufacturing the ITER vacuum vessel within the required tight tolerances and to the required high quality. The experience from the manufacture of a part of the sector has highlighted several distortion issues, which can be compensated for. A local machining tool demonstrated the possibility of vibration-free machining without lubrication, as required in the ITER clean conditions scenario. Although a project to establish the feasibility of cold 3-D forming of the walls showed it was with the capacity of available equipment, a problem of buckling instability may make this method unusable. An alternative method of sector manufacture, using e-beam welding, and avoiding the use of one-sided welds, is described.