A study on boiling water reactor stability behavior

In the framework of the Paul Scherrer Institute (PSI) transient analysis pr oject STARS, a boiling water reactor (BWR) stability analysis methodology b ased on the BWR system code RAMONA3 has been developed. The time series ana lysis based on parametric mixed antoregressive/moving average-models is con ducted by a MATLAB code package using the system identification and the sig nal-processing toolboxes of-MATLAB. A short description of the PSI methodol ogy is presented and two aspects of the stability analysis are discussed. F irst, the physical mechanism underlying the BWR power oscillations from the non-linear feedback system point of view is discussed and second, some exp eriences collected by the analysis of the regional stability phenomenon are presented.