NEUTRON MEASURING INSTRUMENT AND MEASURING METHOD THEREOF

PROBLEM TO BE SOLVED: To provide neutron measuring technique for acquiring a neutron measurement value from power spectrum density of a signal converted into a frequency domain by using Fast Fourier transform to neutron measurement.SOLUTION: A neutron measuring instrument 10 of this invention comprise an analog signal processing system 11 for amplifying only an AC part of a detector output signal from a neutron detector 21 to perform filtering processing of high frequency component removal, a digitalization processing system 12 for digitalizing an output signal from the analog signal processing system 11 into a time series with a signal of a constant sampling period, an FFT arithmetic processing system 13 for converting the constant number of signals on the time domain from the digitalization processing system 12 into a signal of a frequency domain to perform filtering processing, and a signal processing system 14 for selectively extracting a necessary signal of a frequency domain from arithmetic processing of the FFT arithmetic processing system 13 to calculate power spectrum density, and converting the power spectrum density into a neutron measurement value.