[Objective] The helium circulator of the high-temperature gas-cooled reactor (HTGR) is advanced core equipment independently developed by Tsinghua University and is highly important for normal reactor operation. The shutdown of the helium circulator will lead to an emergency shutdown of the reactor, directly affecting the operation of the nuclear power plant and possibly causing safety problems. Therefore, it is necessary to evaluate the reliability of the helium circulator and study the preventive maintenance strategy to ensure the high-quality operation of the HTGR demonstration project (HTR-PM). [Methods] First, we used the failure mode, effects and criticality analysis (FMECA) method to analyze the failure modes, causes, effects, and degree of severity of the components of the helium circulator and list the usage guarantee recommendations. Since FMECA has not been performed on HTGR thus far, we referred to the national military standard to specify the severity degree of the helium circulator's failure consequences. Through FMECA, we can also identify its key components, the parts that must be emphasized during the design and maintenance of the circulator. Then, we used the general component data to determine the failure rate of the circulator and the failure rate proportion of each component. Finally, we used the reliability-centered maintenance analysis (RCMA) method to plan the preventive maintenance strategy of the circulator and put forward preventive maintenance plan suggestions. Preventive maintenance is mainly performed through condition monitoring, function test, etc., which will not affect the normal operation of nuclear power plants. According to RCMA, the preventive maintenance measures of the helium circulator mainly include condition-based maintenance (CBM), usage inspection, function test, and so on. CBM can be performed online, and other preventive maintenance measures can be completed during the overhaul; thus, these measures can effectively improve system availability and reduce financial losses. In addition, the maintenance interval is mainly based on the severity degree and the proportion of the failure rate of components, as well as the corresponding maintenance measures. A more accurate maintenance interval must be updated after receiving the monitoring data feedback. [Results] The calculated failure rate of the helium circulator was 0. 18 times/year, which met the design criteria that the helium circulator shut down due to failure should occur less than once a year. However, a more accurate failure rate evaluation needs to be further updated after accumulating actual operation data. The calculation results showed that the drive motor in the helium circulator exhibited the highest failure rate of 88. 57%, while that of the frequency converter in the drive motor was 60. 82%. Therefore, the reliability of these components should be increased to improve that of the helium circulator. The reliability prediction results can provide a reference for improving the design and then the operation reliability of the helium circulator. [Conclusions] The research process of this paper is significant as a reference for conducting reliability analysis, improving the design quality, and planning maintenance strategy of newly developed nuclear power equipment, and it can also provide insights for relevant analyses of equipment in other nuclear power plants. © 2023 Press of Tsinghua University. All rights reserved.
