STRUCTURAL EVALUATION OF THE NET/ITER OUTBOARD BLANKET BOX

This paper presents the results from a 3-D thermomechanical analysis of the NET/ITER reference design of the outboard blanket box and integral first wall. The influence of the global box behaviour under the thermal and electromagnetic loadings on the detailed first-wall stresses has been determined. The thermal part of this study investigated the influence of the back-plate temperature of the box and the inclusion of radial stiffening ribs on first-wall stresses. Radial stiffening ribs introduced to withstand disruption forces also help to redistribute forces arising from differential expansion between the back plate and first wall; the peak temporal Tresca stress range in the first,wal) with ribs is 269 MPa and without ribs is 316 MPa. The back-plate temperature does not strongly influence the magnitude of the stresses in the first wall. The ribs reduce the first-wall stresses produced by the electromagnetic loads but not to a level which is acceptable when combined with the thermal loads. Comparison between this 3-D analysis and 2-D finite-element calculations highlights the conservatisms present in the previous 2-D analysis used to design the first wall.