Design of the in-wall shielding for the ITER neutral beam port

The ITER neutral beam port is composed of connecting duct, port extension and port stub extension. The spaces between inner and outer shells of the port extension and port stub extension are filled with pre-assembled blocks, called in-wall shielding. The main purpose of IWS is to provide neutron shielding for the superconducting magnet, thermal shield and cryostat from the main vessel during plasma operation. In order to provide effective neutron shielding capability with the cooling water, 40 mm thick flat plates (steel type 304B4) are used in almost all areas of the volume between port shells. The IWS is composed of shield plates, upper/lower brackets and bolt/nut/washers. Major activities during design work are to develop installation concept of the IWS blocks for easy assembly into port structures and to perform structural analysis to assess sufficient strength, fabrication feasibility study and 3D modeling including drawing works. In this paper, major results of mechanical design are introduced. First, the design requirements for IWS and the developed IWS designs for easy assembly into the port structure are introduced. Second, is introduced the engineering analysis results to assess structural integrity. And then the fabrication feasibility study results are presented for major fabrication processes. Lastly, conclusion and future works are mentioned.