Patent ID: 6408041
Filing Date: 2002-06-18
Classification: G21C,Y02E

Abstract:
A power distribution monitoring system for a reactor, comprising:a plurality of in-core nuclear instrumentation assemblies each having a nuclear instrumentation tube, a plurality of fixed neutron detectors housed in the nuclear instrumentation tube and adapted to detect neutron flux of a local power distribution of a power range in a core of the reactor and a gamma-ray thermometer assembly housed in the nuclear instrumentation tube, said gamma-ray thermometer assembly having a plurality of fixed &ggr;-ray heating detectors for detecting &ggr;-ray heating values and a heater built therein and adapted to calibrate the fixed &ggr;-ray heating detectors, said fixed &ggr;-ray heating detectors being arranged at least close to the fixed neutron detectors; means for processing neutron flux detection signals based on the detected neutron flux by each of the fixed neutron detectors; means for processing gamma-ray thermometer signals based on the detected &ggr;-ray heating values to obtain gamma ray heating measurement signals of the fixed &ggr;-ray heating detectors of each of the gamma-ray thermometer assemblies; means for electrically energizing the heater in each of the gamma-ray thermometer assemblies; means for storing a plurality of predetermined time intervals; means for selecting one of the predetermined time intervals for specified &ggr;-ray, thermometer assemblies respectively; means for detecting a core state data representing a state of the core of the reactor; means for detecting a change of the core state according to the detected core state data to determine whether a selected predetermined time interval after detecting the change of the core state elapses; and means for gathering at least one of the gamma-ray thermometer signals and the gamma-ray heating values, wherein said gamma-ray thermometer signal being processed by the gamma-ray thermometer process means from a fixed &ggr;-ray heating detector, and said gamma-ray heating measurement signals being calculated from the gamma-ray thermometer signal; and means for simulating a power distribution in the core according to at least one of the gamma-ray heating measurement signals and the neutron flux detection signals; wherein said energizing means is adapted to control an electrical energy supplied to the heater according to the selected predetermined time interval to heat the heater, thereby executing a heater calibration of output voltage sensitivities of the fixed &ggr;-ray heating detectors of the gamma-ray thermometer assembly when the selected predetermined time interval after detecting the change of the core state elapses.