Analysis and simulation of the flow signal in the recirculation loop of a nuclear power station during a bistable flow event Original Research Article

This study represents a major advance in terms of research into bistable flow and the vibrations of jet pumps inside a vessel of boiling water. Firstly, an analysis is made of a flow signal in a recirculation loop using the Hilbert transform. This study of the temporal flow series concludes that this is a particular case of noise-induced transitions, which, in this case, are induced by turbulence. From this we conclude that the variations in the flow in the recirculation loops are due to turbulence and vortices. Therefore, the cause of the vibrations in the jet pumps is in the flow. Secondly, the identified phenomenon is simulated and the model validated. The model shows a very precise degree of prediction and perfectly reproduces the observed behaviour. Finally, a recommendation to eliminate this problem is set out. The central idea is that if we eliminate turbulence in the central header of recirculation loops, we eliminate or reduce the factors that produce the vortices and turbulence and therefore the bistable flow.