A study of the influence of electron beam welding sequences on the ITER vacuum vessel prototype VATS

This paper presents a detailed finite element simulation of the welds of the prototype Vessel Advanced Technology Segment (VATS) by electron-beam welding. The flexible support housings are reinforcing cylinders of the pressure boundary of the ITER vacuum vessel. They connect inner and outer shells. Eight different simulation sequences were carried out to explain the different mechanisms that drive the distortion process during welding and to lead to an optimum sequence which minimizes the final distortions. The simulations were used to guide the manufacture of the final sequence of the VATS.

► The simulation of distortions can optimise the welding sequences to achieve tight tolerances and low distortion components.
► Simulation can also predict unexpected non linear effects during welding and geometric influence of the component in the final distorted shape.
► The simulation permits determinate the best welding sequence to minimize the distortions in welding components.