Design Features of HANARo Neutron Flux Monitoring System nad Its Operating Experiences

摘要

The Neutron Flux Monitoring System for HANARO provides reliable neutron flux measurement fro mreacctor shutdown to reactor full power level ranging 10 decades from 10 sup 0 nv to 10 sup 10 nv. The neutron flux monitoring system consists of a guarded fission chamber, amplifier and signal processor. The neutron flux as the measure of reactor power is continuously monitored by six(6) fission chambers mounted on the outside wall of the reflector tank in the pool. Three(3) of the fission chambers are used for reactor power control, while the other three(3) are used for tripping the reactor in case of power excursion. Only the wide range fission chambr-based neutron monitoring system is employed for neutron power measurement thereby source range and intermediate range detectors are not necessary and the number of neutron monitoring channels are minimized at HANARO. THis paper discusses some design features and characteristics of the neutron flux monitorng system for HANARO and its operating exeriences. Some unexpected problems and misbehaviors nadtheir corrective actions taken durign the nuclear comissioning are also briefly introduced. It has been proved, through years of oepration that the wide range neutron flux monitoring system for HANARO has a good capability fo providing the neutron flux signals for reactor control as well as reactor protection.