RAMI analysis of ITER CODAC

Abstract

In the ITER project, Reliability, Availability, Maintainability and Inspectability (RAMI) approach has been adopted for technical risk control to guide the design of components and the preparation for operation and maintenance. RAMI analysis of the ITER CODAC System, the central plant control system, was performed in the current design available in the conceptual design phase. A functional breakdown was prepared, resulting in the system being divided into 5 main functions themselves divided into sub-functions. The Failure Modes, Effects and Critical Analysis were performed to initiate risk mitigation actions. Criticality matrices highlight the risks of the different failure modes with regard to their probability of occurrence and the impact on the availability. Identified risks exist on the effect on data storage hardware and for computer software. Reliability block diagrams were prepared to estimate the reliability and availability of each function under stipulated operating conditions. The inherent availability of the mandatory functions for the control of plasma experiments with mitigations was calculated to be 99.2% that is higher than the project required value of 98.8%. Compensating provisions are advocated in terms of design, testing, operation procedure and maintenance requirements in order to reduce risk levels.