Study on the Method for the Safety-Related Instrument Calibration Surveillance Interval Extension of Nuclear Power Unit With Analog I&C System Based on Setpoint and Uncertainty Analysis

Abstract

To extend the intervals of Safety-related Instrument Calibration Periodic Test can shorten the refueling outage period and improve unit economy. Based on the general requirements for extending the Safety-related Instrument Calibration Periodic Test Intervals and in consideration of the characteristics of M310 Nuclear Power Unit with analog I&C System, an evaluation method is proposed and investigated, which consist of instrument drift analysis, protection channel analysis, channel uncertainty calculation, setpoint analysis and relevant channel tests evaluation. The research on the extension of steam generator level transmitter calibration test interval is carried out in detail. The results show that the drift resulting from the interval extension will has no effect on the protection channel setpoint, the acceptance criteria for channel consistency test and channel function test should remain unchanged. The research of this paper has a reference value for unit economy improvement and outage optimization.