Design improvements and R and D achievements for VV and In-vessel components towards ITER construction

There have been several detailed vacuum vessel (VV) design improvements, such as elimination of the inboard triangular support, separate interspace between inner and outer shells for independent leak detection of field joints and revised VV support system to gain a more comfortable margin in the structural performance. The blanket design has been updated; an inter-modular key instead of two prismatic keys and a co-axial inlet-outlet cooling connection instead of two parallel pipes. One of the most important achievements in the VV R and D has been demonstration of the necessary assembly tolerances. Further development of cutting, welding and non destructive tests (NDT) for the VV has been continued, and thermal and hydraulic tests have been performed to simulate the VV cooling conditions. With regard to the R and D for the FW/blanket and divertor, full-scale prototypical mock-ups of the FW panel, the blanket shield block and the divertor components have been successfully fabricated. These results make us confident in the validity of our design and give us possibilities of alternate fabrication methods. (author)