Boiling water reactor instability analysis using attractor characteristics

Abstract

The main purpose of this work is to develop an alternative technique to analyze the neutron flux signal with the aim of determining boiling water reactor (BWR) stability or instability. Another benefit would be to demonstrate the intrinsic stability or even reversibility of the BWR neutron flux and hence, of power.The methodology is based on the attractor morphology analysis. After calculating the time delay and embedded dimension, a tridimensional attractor is constructed. The morphological analysis is based on the attractor center position and the orbit radius value.Analysis results show that all BWRs analyzed have the same attractor shape, meaning the attractor is a system indicator. The orbit radius is a good stability indicator. It is demonstrated that the limit orbit is not reached in any studied case. Reversibility is justified and intrinsic stability is demonstrated.