Coupling of density wave oscillations in parallel channels with high order modal kinetics: application to BWR out of phase oscillations

In this paper, we study the behavior of a system formed by two parallel channels coupled to a multimodal kinetics. The ®rst problem that arises is the calculation of the reactivity coe- cients for the higher modes. This problem is solved by means of the introduction of distribu- tion factors for a given reactor region which depend on the involved modes. We have also performed a detailed analysis of the di€erent instability types which can be obtained from the model changing the boundary conditions and the feedback gains of the fundamental and ®rst harmonic modes