START-UP RANGE MONITOR CALIBRATION SYSTEM AND OPERATIONAL METHOD FOR THE SAME

PROBLEM TO BE SOLVED: To provide a system for executing a calibration test from a central control room side without the need of entering inside of a reactor building and without being influenced by noise.SOLUTION: There is provided a start-up range monitor system 1 comprising: an SRNM neutron detector 2 that measures neutron flux in a start-up range of a reactor; an SRNM pre-amplifier 3; and an SRNM output monitor 4 that converts a signal amplified by the SRNM pre-amplifier 3 to reactor power and is provided with a function of monitoring the reactor power. A signal generator 16 for generating a calibration signal obtained by simulating the reactor power and a variable attenuator 17 for attenuating the calibration signal generated by the signal generator 16 are disposed in a central control room C. An attenuator 21 for attenuating the calibration signal from the signal generator 16 immediately before the calibration signal is input to an amplification circuit 23 and a switching device 22 for switching between inputs of the calibration signal attenuated by the attenuator 21 and a detector output signal from the SRNM neutron detector 2 to the amplification circuit 23 are installed inside the SRNM pre-amplifier 3.