RAMI analysis for the ITER In-Vessel Coils System

Abstract

The ITER project is the largest international collaboration in the scientific field ever set up. It forms the heart of a unique collaborative agreement to build the first experimental nuclear fusion device designed to prove the scientific and technological feasibility of sustained fusion power generation. Among hundreds of systems, the In-Vessel Coils System plays a crucial role in ITER: ensuring and maintaining stable plasma operations. ITER has an ambitious inherent availability target for plasma production. To be able to achieve this objective, the potential technical risk that may affect the machine operation, was assessed by means of RAMI (Reliability, Availability, Maintainability and Inspectability) approach. The RAMI analysis for the IVC system was performed on the system design, following the Staged Approach Configuration adopted by ITER for Construction and Operation phases. A functional breakdown was prepared, resulting in the system being divided into 3 main functions described using the IDEFØ method. A qualitative analysis was performed applying the Failure Modes, Effects and Critical Analysis technique in order to identify the potential effects due to different anomalies of the IVC components. Criticality chart highlights the distribution of the Failure Modes across three risk zones with regard to their probability of occurrence and the impact on the availability. In relation to the operation of the IVC System, the analysis identified 32 risks, none of whom were classified as major. To estimate the reliability and availability of IVC system and to assess the compliance to the requirements, a quantitative analysis was performed using the Reliability Block Diagrams Analysis. The inherent availability of the IVC system during DT phase was calculated over the 20 years of ITER lifetime. The availability of the ITER IVC system results to be compliant with the inherent availability requirement for DT phase.