Structural analysis of the optical hinge preliminary design for the ITER wide angle viewing system diagnostic

Abstract

The ITER Visible/Infrared Wide Angle Viewing System (WAVS) is an optical diagnostic aimed at monitoring the first wall for machine protection purposes. The Optical Hinge (OH) and Optical Relay Unit (ORU) are the first two components in the interspace area and both share a common support structure. The WAVS will be composed by 15 different lines of sight (LoS) distributed around ITER vacuum vessel in Equatorial Ports (EP) 3, 9, 12 and 17. EP12 is currently at its preliminary design and has to be operational for the first plasma. Its development is being carried out by the Consortium constituted by CEA, CIEMAT and Bertin Technologies, within the Framework Partnership Agreement financed by F4E.

The OH mission is to compensate the vertical displacement of the vacuum vessel during operation with respect to the building. Therefore each OH LoS consists of a pair of flat mirrors arranged vertically. The upper one is driven vertically while the other remains fixed. Both mirrors are provided with alignment capabilities to assure their correct installation. The three OH LoS are placed in the OH-ORU common support structure, which is in turn directly attached to the Interspace Support Structure.

In order to assure the optical performance, the OH-ORU common support structure has to withstand thermal and inertial loads during normal operation and SL-1 seism with low deviation (0.3 mm) and tilt (0.5arcmin). In case of Category III and IV (higher seismic or accidental loads) its integrity has to be maintained as it is classified as an ITER Safety Relevant component.

This work comprises the structural analyses performed by CIEMAT of the OH mechanical set to evaluate its optical performance and the ones of the OH-ORU common structure in EP12 to check its integrity in accordance with the RCC-MR Code.