Experimental Study on Neutron Noise Induced by Core Barrel Vibration of Nuclear Reactor

This paper deals with the experiment of neutron noise induced by the core barrel vibration of the critical installation.Three kinds of stimulation including random signal,narrow band sweep frequency signal and single frequency signal are adopted to stimulate the core barrel vibration.At biggest stimulation force,the biggest vibration amplitude is 21μm,generally in 3 to 10μm.The amplitude of the frequency spectrum of background noise presents an exponential reduction with the frequency,at 10Hz frequency,and the amplitude reduces 10 times or so.To this reactor,the frequency spectrum of the neutron noise induced by the core barrel vibration distributes mainly over tens Hz,and may be identified easily.A high-pass digital filter is adopted to improve the the observation and identification of the characteristic spectrum.The characteristic spectrum of neutron noise in the lower and middle frequency range is brought on by the core barrel vibration stimulated by random force.As stimulated by the narrow band sweep frequency force,the of frequency peak at about 125Hz is brought on by the core barrel vibration stimulated by sweep frequency range from 110 to 180Hz.The characteristic spectrum including several frequency peaks is brought on by the core barrel vibration stimulated by single frequency range from 30 to 150Hz.The mode frequencies of the core barrel vibration in normal temperature water are 76.2,125.0,181,215 and 239.7Hz。