Using wavelet analysis an existence of regularities in “noise” signals from neutron flux detectors and temperature ones of a design in-pile control system of PWR-1000 reactor was investigated. For the purpose to check the possibility to estimate coolant parameters through neutron flux parameters and vice versa, a comparative analysis of statistical characteristics for parallel long regular sets of measurements of coolant temperature and a neutron flux was carried out. It were analyzed neutron signals from three measurement canals with ionization chambers, and from temperature sensors for coolant of the cool and hot branches of the first contour. In both variables a rich spectrum of various long time (tens of minutes and hours) periodicities has been revealed. Some of them are found both in temperatures and in the neutrons flux. It was however revealed also periodicities, which in neutrons and in a coolant do not correlate between themselves. The differences between the pictures of wavelet transform of temperatures of hot and cold branches of the first contour have been shown. In the temperature of hot branch additional more high frequency vibrations, which can be ascribed to development of turbulence, are arisen. The conclusion was drawn, that fluctuations of signals, that have been analyzed, are not random noise, but are the data carrier about neutron subsystem of a reactor. It is suggested to carry out the analysis of fluctuations of signals of a design in-pile control system for early detection of a reactor operating conditions.
Keywords: nuclear reactor, neutrons, coolant, noise statistics.
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