LAUSR

Abstract In this paper the propagation mechanism of the temperature fluctuations of the coolant is investigated using the measured hot and cold leg temperature signals of the primary loops of a VVER-440 reactor. The aim of the investigation was to provide an estimation of the reactor heat transfer function between the cold and the hot leg of the primary circuit, which was enabled by the finding that the ratio of the auto power spectral density functions of temperature noise of the reactor and the steam generators can be well approximated with the ratio of the spectra of the hot leg and the cold leg temperature noise. It was found that the effect of the control system and the power feedback cannot be neglected up to 0.2 Hz for VVER-440 reactors. The transfer properties of the steam generator were estimated using temperature noise measurements as well.