RAMI approach as guidance for optimizing the design of the WEST machine protection system using IR thermography measurements

Abstract The WEST project (Tungsten ( W ) E nvironment in S teady State T okamak) is targeted at minimizing risks in support of the ITER divertor strategy. Part of the machine protection system will be based on S hort W ave I nfra R ed ( SWIR ) thermography diagnostic which consists in monitoring and controlling in real time the power load on the plasma facing components through the surface temperature measurements. The inherent availability objective of such a machine protection diagnostic is essential for WEST operation. A functional analysis of the IR system from highest level main functions down to basic operational functions has been developed. The availability of the initial design has been assessed by making a RAMI ( R eliability, A vailability M aintainability and I nspectability) analysis. Despite mitigation actions to reduce the frequency of potential failures and their time to repair, the availability required by the project could not be reached. With the aim of achieving the availability target, a recommendation was made to consider an alternative design. This paper presents a RAMI analysis of the IR thermography diagnostic whose results have led to modifying the design of antennas protection system to a more available system as required by the WEST project.