IMPROVEMENT IN MEASURED VALUE ACCURACY OF FLOWRATE AT CORE OF BOILING WATER REACTOR

摘要

PURPOSE: To obtain core flowrate excluding uncertainty affected by core power to the relation between differential pressure and core flowrate with the reading of local power range monitor and a quadratic expressing the relation between the differential pressure between two sides of core support plate fluid isolation wall and the flowrate. CONSTITUTION: Sixteen fuel bundles are supported with a group of control rod guide tubes H placed by penetrating a core support plate 30. The differential pressure between two sides of the support plate 30 is measured with a pair of pressure gauges 32 and 34. Each of the fuel bundle groups 36 consisting of 16 fuel bundles is monitored with a local power range monitor. Similarly, the local power range monitor series 54, 56 and 58 monitors the performance of the core C. These monitors 54, 56 and 58 are provided with neutron sensors for local power range monitoring. Part of local power range monitors arranged at an interval from the circumference of the core C is provided with thermocouples 52 to measure the temperature at the core inlet. By using two independent linear equations concerning core support plate differential pressure obtained from the result of thermohydrodynamic analysis and filter-processed neutron flux, the core flowrate is calculated.