An Approach to reduce measurement uncertainty of fuel channel coolant flow rate for Candu plants with a Crossflow ultrasonic flow meter

It has been reported that the indications of some safety feeder line flow rate in Candu plants show steadily decreasing trend during power operation. The challenge is therefore to distinguish between a true flow decrease and a drop in indicated flow due to changes in station flow instrumentation. In relation to this phenomenon, Korea Hydro and Nuclear Power Company (KHNP) plans to install Crossflow ultrasonic flow meter (UFM) on the safety feeder channels for the calibration of existing orifice-type flow meters. The paper introduces the KHNP technical approach and the relevant problem-solving experience in other countries for this issue. In addition, KHNP experience of feeder flow measurements in Candu plants, operating principle and technology validation of Crossflow UFM are presented in the paper. (authors)