Bifurcation analysis of out-of-phase oscillations in boiling water reactors using multipoint neutron kinetics. (February 2020)

• Record Type: Journal Article
• Authors: Vora, Rohan; Chakraborty, Abhishek; Singh, Suneet
• Is Part Of: Progress in nuclear energy. Volume 120(2020)
• Publication Date: 2020-02
• Subjects: Stability analysis -- Multipoint reactor kinetics -- Hopf bifurcation -- Out-of-phase oscillations; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 333.7924
• DOI: 10.1016/j.pnucene.2019.103218
• Languages: English
• ISSNs: 0149-1970

Abstract

Abstract: Stability analysis is important for identifying the safe operating regimes in Boiling Water Reactors (BWRs). The power instabilities, due to the fuel and coolant void feedbacks, can be either in-phase or out-of-phase. The models used in earlier studies were quite complicated, hence, not suitable for bifurcation analysis. In this paper, a simpler model based on neutron multipoint kinetics coupled with coolant temperature feedbacks, with reasonable accuracy is presented for bifurcation analysis of spatial oscillations in BWRs. The stability maps in different parametric planes are constructed using MATCONT. Both supercritical and subcritical Hopf bifurcations are observed and the Generalized Hopf points are also identified. Identification of subcritical Hopf is important as the linearly stable region may have unstable limit cycles near the stability boundary. The region in the stability map where in-phase oscillations are stable whereas the out of phase oscillations are unstable is identified and verified by numerical simulations. Highlights: Multipoint kinetics used for out of phase oscillations in BWRs. Spatial power oscillations due to coolant void and Doppler feedbacks are studied. Non-linear stability analysis has been performed. Existence of Hopf bifurcation found in different parametric planes.