MONITORING AND ANALYSIS OF NUCLEAR-POWER-PLANT SIGNALS BASED ON NONLINEAR DYNAMICAL METHODOLOGY

The spatial correlation of a trajectory in the state space drawn by a dynamical system gives the information (fractal) dimension of the syst em, and enables the onset of the limit-cycle (or persistent) oscillati on to be examined. On-line monitoring system with this methodology was established for a PWR-type nuclear power plant (NPP). The potential u se of this methodology in monitoring NPP was tested from two actual si tuations in which anomaly developed. The spatial correlations of vario us NPP signals under normal operating conditions were calculated, yiel ding information unobtainable by conventional linear methodology. For example, results indicated that the coolant pump vibration was not lin early stabilized, that is, it was a limit-cycle oscillation. Swelling oscillation in the pressurizer pressure was also discovered by this me thodology.