BWR stability and bifurcation analysis using reduced order models and system codes: Identification of a subcritical Hopf bifurcation using RAMONA

Linear stability analysis of flow instabilities with a nodalized reduced order model in heated channel

“…Applying state space approach, these nonlinear ODEs are used to determine the stability of the system. The results of the present model are compared with various existing models [33,34,36] which are closer to exact solutions [31]. The SBs obtained show good agreement with the said models.…”

“…It is worth noting that this left shift in stability boundaries due to increase in number of nodes indicates that as the number of nodes increases, the stability boundary become closer to the exact solutions even in the presence of linear approximations of single phase enthalpy and two-phase quality. The shift pattern due to different combinations of approximation techniques and exact solutions can be found in several literatures [31,33,34].…”

“…The whole system is analyzed by a 1-D axial flow model using three basic conservation PDEs of mass, energy and momentum along the length of the channel. These PDEs are reduced to corresponding ODEs, using weighted residual procedure [20,33,34,38]. Though in real situation the system dynamics is complex, but some simplifying assumptions are made [20,38] to develop the model that helps to simulate the stated phenomenon.…”

“…Clausse and Lahey [32] developed a simple model using approximations for spatial dependence of the single phase enthalpy and two-phase density. Followed by these developments Karve [33], Dokhane [34] and Dokhane et al [35] developed models for DWO by introducing quadratic profiles of single phase enthalpy and two-phase quality using HEM as well as drift flux model (DFM). However due to the presence of quadratic profiles, the system equations became highly complicated and even run for several pages.…”

Analysis of a BWR Stability Behavior using Generalized Discrete Shannon Functions. Application to Ringhals and Forsmark Benchmarks Data

“…In this last case, the amplitude of the oscillation is growing, amplifying the non-linear behavior, which in some cases can induce the 1 Hz band of frequencies. 3,4) The fluctuations or oscillations of neutron signals can be described by stochastic nonlinear dynamics methods with a global-regional interaction. 1,23,31) In case of regional oscillations, we can directly observe the 0.5 Hz oscillation in the LPRM signals.…”