Failure mode and reliability study for Electrical Facility of the High Temperature Engineering Test Reactor

Abstract

The first-of-a-kind commercial electricity and hydrogen cogeneration system is being designed by the Japan Atomic Energy Agency (JAEA) to establish the industrial application of the High Temperature Gas-cooled Reactors (HTGR). The High Temperature Engineering Test Reactor (HTTR) is expected to be coupled with a test cogeneration plant to demonstrate its safety features and justify further HTGR technology development. The aim of this work was to assess the frequency of the unplanned outages of such a plant due to the failures of the HTTR Electrical Facility. The system analysis has been performed followed by the Failure Mode and Effect Analysis (FMEA). The new FMEA-based Gradual Screening Approach has been proposed and applied in order to select the most relevant failure modes. The initial calculation performed for the standard configuration of the system indicated that the reliability may be insufficient for its long-term commercial operation, as planned for about 20 years. Therefore, several modifications of the design have been proposed, aiming at the reliability enhancement. However, the updated results are still below the industrial standards. This opens up a new field of research in reliability engineering and creates a challenge for the HTGR-based cogeneration plants consisting of the joint nuclear-chemical facilities.