Abstract: A safety grade protection system for monitoring parameters indicative of the status of a core of a nuclear reactor, and reducing the criticality of the nuclear reaction when the onset of unsafe conditions are detected. The invention directly detects, in real time, the power at a plurality of axial and radial locations within or about the core and provides a three-dimensional real-time core power output. The system processes those outputs together with a measure of core coolant inlet temperature, pressure and flow rate to calculate, in real time, the fuel centerline temperature, the heat transfer condition at the fuel elements' boundary and the rate of power change within the core.

Abstract: A nuclear reactor monitoring system includes incore and excore neutron detectors for producing neutron noise signals and system data including at least one of reactor coolant pump motor current, temperature and pressure of the reactor coolant system and pressurizer pressure and means for diagnosing conditions of the reactor internals and core support structures by comparing analyzed instrumentation signatures. The signatures may be derived from scale model test data, plant test data, analytical model results and trending analysis results. Analyses performed by the system include time and frequency domain analyses of the neutron noise signals and the system data. The analyzed data are compared with rules in a rules base of an expert system to generate a diagnosis of the condition of the reactor internals and core support structures and action recomendations for maintenance of the nuclear reactor.