A Study on Boiling Water Reactor Stability Behavior

In the framework of the Paul Scherrer Institute (PSI) transient analysis project STARS, a boiling water reactor (BWR) stability analysis methodology based on the BWR system code RAMONA3 has been developed. The time series analysis based on parametric mixed autoregressive/moving average models is conducted by a MATLAB code package using the system identification and the signal-processing toolboxes of MATLAB. A short description of the PSI methodology is presented and two aspects of the stability analysis are discussed. First, the physical mechanism underlying the BWR power oscillations from the nonlinear feedback system point of view is discussed, and second, some experiences collected by the analysis of the regional stability phenomenon are presented.