Rigid and adjustable fixation of the shielding modules into the ITER port plugs

Abstract During the final design review of Diagnostic Port Plugs, it has been highlighted that the current system of fixation, based on gaps, while it is not harmful for the port plug, it throws large uncertainties over the alignment of the optical systems placed inside the DSMs at the same time that the real mechanical behavior of the assembly is clearly unknown. Because the DSM is not rigidly fixed to the Port Plug structure, the DSM and its internal components suffer, during abnormal events like seismic or electromagnetic disruptions, an important level of amplification on the accelerations induced. This magnification is largely derived from a rattling effect that the DSM is vibrating inside the port plug. This effect produces an increase of the efforts acting on the anchoring components of the port plug at the same time that the final position of the DSM after an abnormal event is unknown and greatly influenced by the manufacturing and assembly tolerances. In order to solve all these issues, a new locking system has been developed based on a rigid configuration. Non-relevant modifications are required in the Port Plug structure or in the DSMs for the implementation of this new system because the interfaces are kept intact. Results based on this new configuration are available and they present an important attenuation of the induced accelerations on components inside the DSMs. In addition, the system permits the individual adjustment of each one of the interfacing component to finally achieve the correct aligned positions. Therefore, this new locking system has been assumed for all IO Diagnostic Port Plugs.