Applying HAZOP analysis in assessing remote handling compatibility of ITER port plugs

► We applied HAZOP analysis to assess the criticality of remote handling maintenance activities on port plugs in the ITER Hot Cell facility. ► We identified several weak points in the general upper port plug maintenance concept. ► We made clear recommendations on redesign in port plug design, operational sequence and Hot Cell equipment. ► The use of a HAZOP approach for the ECH UL port can also be applied to ITER port plugs in general. This paper describes the application of a Hazard and Operability Analysis (HAZOP) methodology in assessing the criticality of remote handling maintenance activities on port plugs in the ITER Hot Cell facility. As part of the ECHUL consortium, the remote handling team at the DIFFER Institute is developing maintenance tools and procedures for critical components of the ECH Upper launcher (UL). Based on NRG's experience with nuclear risk analysis and Hot Cell procedures, early versions of these tool concepts and maintenance procedures were subjected to a HAZOP analysis. The analysis identified several weak points in the general upper port plug maintenance concept and led to clear recommendations on redesigns in port plug design, the operational sequence and ITER Hot Cell equipment. The paper describes the HAZOP methodology and illustrates its application with specific procedures: the Steering Mirror Assembly (SMA) replacement and the exchange of the Mid Shield Optics (MSO) in the ECH UPL. A selection of recommended changes to the launcher design associated with the accessibility, maintainability and manageability of replaceable components are presented.