Analysis of neutron flux noise due to coolant parameter fluctuations in a VVÉR core

The results of investigations of noise appearing in the signals from direct-charge sensors of the in-reactor monitoring system of VVER reactors as a result of coolant parameter fluctuations are presented. The calculations and experimental data are used to analyze the dependence of the amplitude of the neutron flux oscillations (local intensity) at the locations of sensors as a function of the magnitude and frequency of the fluctuations of a specific coolant parameter. The NOSTRA program was used to perform the calculations. The results of the analysis were used in the in-reactor noise diagnostics system in the No. 3 unit of the Kalinin and the No. 1 unit of the Tianwan (China) nuclear power plants.