29th Symposium on Fusion Technology (SOFT 2016)

O4A.2 RAMI analysis of the ITER LFS CTS system

Sep 8, 2016, 11:20 AM

20m

Forum Hall 2nd floor (Prague Congress Centre)

Board: 2

Oral D. Diagnostics, Data Acquisition and Remote Participation O4A

Speaker

Elsa Henriques (LAETA, IDMEC, Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal)

Description

This paper describes the preliminary RAMI analysis for the ITER Low Field Side Collective Thomson Scattering (LFS CTS) system based on its preliminary architecture achieved at the System Level Design. The benefits and challenges involved in a RAMI analysis since the front end of the design process of the system are discussed together with the methodology pursued. The Functional Analysis, developed both at system and sub-system level, are the major inputs for the RAMI analysis. This study includes the Failure Mode, Effects and Criticality Analysis (FMECA) and the Reliability Block Diagram (RBD) of the system. Criticality charts are developed to highlight the risk levels of the different failure modes, with regards to their probability of occurrence and effects on the availability of the ITER machine. Mitigation actions are proposed in order to reduce these risk levels in case of impact in the ITER operation. The FMECA analysis has identified two components of the system whose failure will have impact in the ITER operation: the cooling system and the evacuated waveguide in primary Vacuum. The RBD analysis shows that the initial (before mitigation) availability results are 33% obtained for the system and 96% for the ITER operation, when all components are considered to be in series. An independent analysis has been developed to assess the reliability and availability of the system: the receiver transmission lines are in m-out-of-7 parallel reliability-wise relationship and the remaining components in series. When a high level of redundancy in the receiver transmission line is considered the availability of the system is slightly above 70%. However for lower levels of redundancy the availability is clearly damaged and can be as low as 33% if all transmission lines have to be in an operational condition for the system to be considered as available.