Thermal and mechanical behavior of the first wall in fusion reactor

Two and three dimensional finite element models have been developed to understand the thermal and mechanical behavior of the first wall in ITER. This work attempts to assist with the first wall design by evaluating how important factors affect the first wall behavior. These factors include the effects of the different joint modes at the interface of different materials and constraint conditions such as free to expand or highly constrained. The two dimensional model, containing only half of the water channel due to the symmetry of the geometry, simulates a slice of the small segment of the outboard of the first wall. The simulation domain contains four regions which are made of three different materials, i.e., beryllium, copper and stainless steel. Compared with the 3D model, it greatly reduced the mesh size and therefore required less efforts and computational expenses. It was found that in most of the region of the first wall, the 2D approximation is a good assumption, thus a large number of the simulations can be carried out with the 2D model to understand various heat transfer and mechanical phenomena in the first wall design