Abstract: According to an embodiment, a neutron measurement apparatus has: a neutron detector; a preamplifier that amplifies an output signal of the neutron detector and outputs a neutron detection signal; a pulse counting unit that measures the neutron intensity by using pulse counting method by which the neutron detection signal is used to count the number of individual pulses; a Campbell measurement unit that measures the neutron intensity by using Campbell method by which a time average of squares of AC component of the neutron detection signal is calculated; a correction constant calculation unit that calculates a correction constant for correcting an output of the Campbell measurement unit by using an output of the pulse counting unit and an output of the Campbell measurement unit; and a correction value calculation unit that outputs, based on the output of the Campbell measurement unit, a corrected value by using the correction constant.

Abstract: According to an embodiment, a neutron measurement apparatus has a neutron detector; a pre-amplifier; a first AC amplifier which extracts and amplifies an AC component; a bandwidth limiter which obtains a signal of a range of a predetermined frequency domain based on the output of the first AC amplifier; a neutron signal interval calculation unit which derives a neutron signal interval, that is a period of time during which a significant signal is being generated, from the AC component of the neutron detection signal; and a mean square value calculation unit which calculates a mean square value of outputs of the bandwidth limiter for a range corresponding to the neutron signal interval.

Abstract: According to an embodiment, a neutron measurement apparatus has: a neutron detector; a preamplifier that amplifies an output signal of the neutron detector and outputs a neutron detection signal; a pulse counting unit that measures the neutron intensity by using pulse counting method by which the neutron detection signal is used to count the number of individual pulses; a Campbell measurement unit that measures the neutron intensity by using Campbell method by which a time average of squares of AC component of the neutron detection signal is calculated; a correction constant calculation unit that calculates a correction constant for correcting an output of the Campbell measurement unit by using an output of the pulse counting unit and an output of the Campbell measurement unit; and a correction value calculation unit that outputs, based on the output of the Campbell measurement unit, a corrected value by using the correction constant.

Abstract: According to one embodiment, a stability computation monitoring device monitors in real time reactor power oscillation based on signals from neutron detectors. The device has: a detection sampling section sampling signals from the plurality of neutron detectors to output a detection sampling signal for each neutron detector; a local power monitoring section converting the detection sampling signal into a neutron flux signal; a low-pass filter applying low-pass filtering to neutron flux signal; a down-sampling section performing down-sampling for the neutron flux signals that have passed through the low-pass filter at a period longer than the detection sampling period; a wavelet transformation section applying Discrete Wavelet transformation to the neutron flux signals that have been subjected to the down-sampling to compute a DWT wavelet coefficient of each level; and a monitoring section monitoring the wavelet coefficient computed by the wavelet transformation section.

Abstract: A neutron measurement apparatus includes: an analog signal processor; a digitizing processor; an FFT calculation processor; and a signal processor. The analog signal processor amplifies alternating current components of detector output signals output from a neutron detector, and filters to remove high frequency components from the output signals, which the digitizing processor digitizes at a constant sampling period in a time series; the FFT calculation processor converts certain of the signals in a time domain from the digitizing processor into signals in a frequency domain, and filters the signals in the frequency domain; and the signal processor selects and extracts signals having required frequency components through the calculation processing on the FFT calculation processor, to calculate power spectral densities of the extracted signals, and to convert the calculated power spectral densities into a neutron measurement value.