Structural analyses for equatorial and lower ports of the ITER vacuum vessel

To investigate the structural integrity of the ITER vacuum vessel (VV) and ports, the structural analyses of the regular equatorial and the lower remote handling (RH) ports have been performed. The advanced design of the equatorial regular port adopting a pure friction type flange has been recommended as a reference design by the ITER International Organization. The structural integrity of the equatorial port flange, sealing unit, and connecting duct has been reviewed by conducting nonlinear finite element analyses. The advanced design of the regular equatorial port flange with proper pretension is acceptable in the structural design point of view.From the local analyses for a connecting duct and a sealing unit, it has been found that the stresses are less than the allowable values.The structural analyses of the lower RH port have been also performed to verify the capability for supporting the VV. Since high local stress occurs at the gusset and supporting block, the case study for the lower port has been conducted to mitigate the stress concentration and to modify the component design. The strength of the lower RH port structures can be improved by the design modification of poloidal and toroidal gusset.