Flux, reactivity, steam void, and steam-water inter-layer noise spectrums in the EBWR

Abstract

The reactor flux noise was recorded and Fourier analysed. It showed a resonance peak in the energy-frequency spectrum and was not a ‘white’ noise. Such was also the case for the reactivity spectrum, obtained by operating on the flux spectrum with a measured power transfer function. A transfer function relating the power ( N) to a steam-water inter-layer input was calculated by using the reactor dynamic model. The inter-layer spectrum obtained by operating on the flux spectrum with this function was ‘white’ over a frequency range of 30 to 1, and probably is the result of random variation of the steam generation rate due to discrete steam bubbles entering the steam space. Such noise spectrums can be employed for gross stability investigations if a fair knowledge of the dynamic model is in hand.