Research on Ultrasonic Technology of Accurate Measurement of Main Feedwater Flow in Nuclear Power Plant

A high-precision ultrasonic flow meter with a design measurement uncertainty of 0.3% has been investigated and developed for the measurement of the main feedwater flow in the secondary loop. This flowmeter could be used to realize the small power enhancement of PWR nuclear power units. The influences of flow measurement under high temperature and high pressure were sequentially analyzed through the method of uncertainty decomposition. The influence of the flow condition variation caused by high temperature on the measurement can be partially verified by the real flow calibration of the calibration coefficient under normal temperature and pressure and medium temperature. The change of the tube structure size could be obtained by finite element simulation and measurement on a static experimental equipment which could create a high temperature and high pressure environment. The error introduced by the flow integral algorithm could be obtained by CFD simulation and verified by real flow calibration. The results show that each component can be quantified and traced back by using the flow standard device under the existing domestic conditions. Therefore, the measurement uncertainty of the main feedwater flowmeter developed in this thesis can finally achieve the design target.