Nuclear analysis of the ITER In-Vessel viewing system

The In-Vessel Viewing System (IVVS) is a diagnostic tool in ITER to perform in-vessel inspections between plasma pulses or during shutdown. During plasma pulses, the IVVS is parked inside a dedicated port extending from the vacuum vessel (VV) to the port cell (PC). The IVVS design must fulfill specific requirements related to the service lifetime of sensitive parts and to the radiation effects on neighbouring components and the PC. Analyses were performed to determine nuclear responses in the IVVS and neighbor components at plasma operation and after shutdown. The neutron flux map shows improvements due to improved shielding in the neighbouring lower ports and gives insight to further possibilities of reducing nuclear loads to IVVS sensitive components. The activation analysis reveals that the major contributors to the decay photon source are the movable shield block counterweights.