Analysis of the Discrepancies of Reactor Coolant Flowrate Measurement in Unit 2 of Ling’ao Nuclear Power Plant

Based on the reactor coolant flow rate measurement principles and various data measured, analysis is performed on the abnormal phenomena in the reactor coolant flow rate measurement of Loop No.2, during the commissioning of unit 2 of Ling'ao Nuclear Power Plant. Together with site tests and test verification, it has been found that the root cause is the minor manufacturing deviation of the flow rate sensor. The temporary solution has been made to displace the flow rate transmitter range and adjust the parameters of the flow rate measurement circuit. Meanwhile the permanent solution to replace the flow rate transmitters during the first refueling outage is being proposed.