Abstract: Radiation monitor is used in PWR nuclear power plant to monitor the concentration of N-16 radionuclide in the main steam pipe, and then to calculate the damage rate of steam generator. Because the steam generator leakage monitor works in high temperature and humidity environment for a long time, the failure rate of the monitor is high, which may affect the normal operation of the nuclear power plant. In this paper, the fault diagnosis, fault cause analysis and repair technology research of six SGLM201 steam generator leakage rate monitors are completed, and the technical maintenance scheme and the whole machine damp heat protection and reinforcement technical scheme are put forward for each fault. After repair, the monitor is verified by environmental test and calibration test, which proves that the technical maintenance scheme proposed in this paper is feasible, which can effectively reduce the failure rate of the equipment and improve its long-term operation reliability.

Key words: steam generator, leak rate monitoring, maintenance technologies;N-16;nuclear power plant