Failure rate adjustment factors for high technology components

Abstract

In nuclear fusion research for power plant applications, experiments have used tritium fuel. With the use of radioactive tritium, the safety issues have increased and so have the safety assessments to demonstrate that safety is incorporated into design. For the ITER International Project, the safety concerns of a high power, tritium-burning experiment are being addressed in design. ITER also has another issue of interest, to give a reasonable forecast of the operational availability of this largest fusion experiment ever built. Both of these needs can require component failure rate data for safety assessment and for reliability availability maintainability inspectability (RAMI) studies. ITER is often using components of greater size, at higher temperatures, and at higher radiation damage levels than past experiments. In some cases, the component failure rates from previous operating experiences can be modified with multiplicative factors, called k factors or adjustment factors, to account for the different operating environments. With the use of k factors, the component failure rates from past operations can be applied to this new design. When the environments are defined, the k factor approach can be used with good effect to give component failure rate estimates. This paper describes recent work in developing k factors to adjust some magnet component failure rates for the ITER International Project.