A survey of failure experience in existing superconducting magnet systems and its relevance to fusion power reactors

Details of existing superconducting magnet failures are collected and evaluated with regard to future CTR superconducting magnet safety and reliability. Fourteen magnet systems with sixteen failures are presented. These failures are analyzed and categorized as to causative factors (eg. hot spots, arcing, lead failures, and conductor movement). Responses of the instrumentation and protection systems during these accident situations are also presented. Repairs and present status of the magnets are described. Preliminary conclusions are: the failure rate of existing magnet systems is too high to be tolerable for CTR magnets; although failure analyses of present systems can be used as a reference for future CTR magnet safety design, the prediction of successful operation of CTR magnet systems represents a significant extrapolation from the experiences accumulated so far; much development work and repeated testing of magnet system components and sub-systems are required.