ON THE QUALIFICATION OF BOILING WATER REACTOR STABILITY MARGIN INDICATORS USING LINEAR STABILITY ANALYSIS

摘要

This paper adresses some important issues concerning BoilingWater Reactor (BWR) stability.rnThe first issue is the relation between the Decay Ratio (DR) and the operational stability margins.rnIt is shown that it can be misleading to use solely the value of the DR in BWR stabilityrnmonitoring as an indicator for stability. The second part of the paper examines the stabilityrncharacteristics of a natural circulation BWR via the root-loci of the complex poles of therncharacteristics equation of the system. The different instability mechanisms of thernthermalhydraulic subsystem of the reactor cannot be attributed to one pole pair. For thernthermohydraulic subsystem of a BWR, always the same pole pair dominates and determines thernstability. However, the root loci of the reactor system show that two different pole pairs can berninterchanged in dominating the system stability, depending on the strength of the void reactivityrnfeedback.