Enhanced core flow measurement in the advanced boiling water reactor

A method for the accurate measurement of core flow required to support several critical control and safeguard functions for the advanced boiling water reactor (ABWR) is described. The ABWR incorporates reactor internal pumps for reactor coolant recirculation. An adaptive measurement method has been adopted. It combines core support plate differential pressure and neutron flux measurements to derive core flow. A steady-state heat balance calculation is combined with other process measurements to obtain an accurate calibration reference for the adaptive cores flow measurement method. The uncertainty of the core flow estimate calculated from core plate differential pressure measurements can be substantially reduced by incorporating the core power adjustment and the improved calibration method described. Use of these enhancements can result in a core flow measurement system that satisfies the accuracy requirements of all the critical ABWR control and safeguard functions.