The evaluation on the effect of shell thickness reduction for ITER vacuum vessel sector 1 and 6

► The thickness reduction effect of vacuum vessel during fabrication was evaluated. ► Linear elastic and nonlinear limit analyses were performed to confirm the design. ► The effect of thickness reduction is not critical in the structural point of view. ► The vacuum vessel with thickness reduction meets the design criteria of RCC-MR. The structural analyses of vacuum vessel have been performed to investigate the effect of shell thickness reduction on structural integrity. The finite element models of vacuum vessel considering original design and thickness reduction have been developed. The expected maximum thickness reduction possibly caused by forming and bending processes during fabrication was applied to the curved region of the analysis models. The linear elastic and nonlinear limit analyses have been performed. The structural integrity of main vessel including lower port stub extension has been verified in accordance with the requirements of RCC-MR. It is concluded that the inner and outer shells of main vessel still have enough strength margins under pressure and VDE (Vertical Displacement Event) load conditions in spite of thickness reduction. These results have been reviewed and approved by ITER Organization and ANB (Agreed Notified Body).