BWR stability investigation at Forsmark 1

Bergdahl, B.-G.; Reisch, Frigyes; Oguma, Ritsuo; Lorenzen, J.; Åkerhielm, F.

doi:10.1016/0306-4549(89)90002-9

Cited by 41 publications

(4 citation statements)

References 8 publications

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“…-45- (2) The kinematical competition of the principal and the secondary unstable modes of oscillation due to different types of feedback can appear when the parameter arc in this model takes extremely large values as shown in Fig. 3.…”

Section: Vh Concluding Remarksmentioning

confidence: 95%

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Nonlinear Dynamics of Reactor with Time Delay in Automatic Control System and Temperature Effect

Konno¹,

Hayashi²,

Shinohara³

1992

Journal of Nuclear Science and Technology

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The authors have studied the dynamical features of limit cycle oscillations in a nonlinear reactor system equation with feedback time delay in both control system and temperature effect by taking account of the experience in the pulsed reactor NSRR before its recent modification.The features of competition between the two delayed feedback effects are analyzed. A theoretical method for predicting analytically the mean amplitude of limit cycle oscillation is also developed by combining the method of Krylov-Bogoliubov and that of nonlinear transformation. Further, the effects of colored external noise on the profiles of power oscillations is investigated from the viewpoints of "global stability" and "non-linear response".Their new findings are summarized as follows : (1) Without an external noise, chaotic oscillations can arise when the product of the applied reactivity and the delay-time is very large. However, it does not appear when this product term takes a small value. (2) On the other hand, near the first Hopf bifurcation under the influence of external noise, the limit cycle oscillation becomes chaotic one as a superposition of quasi-periodic oscillations, which can be identified by the stochastic Van der Pol equation. The sinusoidal limit cycle oscillation of reactor power observed in the NSRR has such a stochastic nature rather than kinematic one.

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Section: Vh Concluding Remarksmentioning

confidence: 95%

“…Here we must explain the physical significance of our approach based on the simple model ( 2) to the problem of power oscillation. The effect of the precursors and the effect of the space-dependence are very important for describing the dynamics of a reactor in a stable state.…”

Section: ·Dtn=·a (Po+p/t)-rrn(t--rr) -Rcnct--rc))n(t)mentioning

confidence: 99%

Nonlinear Dynamics of Reactor with Time Delay in Automatic Control System and Temperature Effect

Konno¹,

Hayashi²,

Shinohara³

1992

Journal of Nuclear Science and Technology

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“…First; BWRs can experience in-phase (core wide) or out-of-phase (regional) NCTH oscillations (March-Leuba and Blakeman, 1991). Second; some NCTH instabilities in operating reactor cores and in controlled experiments in BWRs have resulted in stable, finite amplitude oscillations (Farawila et al, 1996;Bergdahl et al, 1989;Gialdi et al, 1985), while others led to oscillations with growing amplitude, until stopped by automatic or manual scram (Kruners, 1998;Cheng et al, 1988). While in-phase and out-of-phase oscillations can be predicted by linear analysis using a detailed model of the core physics, analysis of the second phenomenon -which has received less attention in the past -necessarily requires the set of nonlinear equations either integrated numerically or studied using analytical bifurcation techniques.…”

Section: Introductionmentioning

confidence: 97%

Turning points and sub- and supercritical bifurcations in a simple BWR model

Rizwan-uddin

2006

Nuclear Engineering and Design

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“…BWR power oscillation experience outside the United States include the Coarso NPP in Italy [36], the Ringhals-1 in Sweden [37], and the Cofrentes NPP in Spain [38]. In the United States, several significant BWR power oscillation events occurred.…”

Section: Introductionmentioning

confidence: 99%

Predictive Methods for Stability Margin in BWR

Román¹

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iii This dissertation is dedicated to my mother, wherever she is now, who always gave me encouragement, love and support, my father raised me with infinite patience and advised me to obtain a degree in physics, my sister Pilar, example to follow both in the study and teaching and, especially my family, because this work has been done during the time I had to spend with my wife Marina, and my children Cecilia and Jose Andrés.I also want to thank my supervisors, Alberto Escrivá and José Luis Muñoz-Cobo without them this thesis would not have been possible. I also thank this work to José María Izquierdo Rocha who taught me to be rigorous and convinced me of the need for a thorough knowledge of nuclear engineering. To all my colleagues who have made me what I am today.Thanks to all v SUMMARY Power and flow oscillations in a BWR are very undesirable. One of the major concerns is to ensure, during power oscillations, compliance with GDC 10 and 12. GDC 10 requires that the reactor core be designed with appropriate margin to assure that specified acceptable fuel design limits will not be exceeded during any condition of normal operation, including the effects of anticipated operational occurrences. GDC 12 requires assurance that power oscillations which can result in conditions exceeding specified acceptable fuel design limits are either not possible or can be reliably and readily detected and suppressed.If the oscillation amplitude is large, before the scram occurs the fuel rods may experience periodic dry-out and rewetting, or if the oscillation is larger enough, extended dry-out.The Decay Ratio (DR) is the typical linear stability figure of merit. For analytical estimation of DR frequency domain codes are very useful. These types of codes are very fast and their results are very robust in comparison with time domain codes, whose results may be dependent on numeric scheme and nodalization. The only drawback of frequency domain is that you are limited to the linear domain; however, because of regulatory requirements imposed by GDC-12, reactors must remain stable and, thus, reactors always operate in the linear domain.LAPUR is a frequency domain stability code that contains a mathematical description of the core of a boiling water reactor. It solves the steady state governing equations for the coolant and fuel, and the dynamic equations for the coolant, fuel and the neutron field in the frequency domain. Several improvements have been performed to the current version of the code, LAPUR5, in order to upgrade it for use with new fuel design types. The channel geometry has been changed from constant area to variable area. The local losses due to the spacers and contractions along the flow path have been upgraded to use industry standard correlations. This new version is LAPUR 6.In this work, in order to check the correct implementation of these changes, a two-fold LAPUR 6 validation has been performed: vi First, an exhaustive validation of the models implemented has been performed, comparing single channels LAPUR 6 outputs...

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BWR stability investigation at Forsmark 1

Cited by 41 publications

References 8 publications

Nonlinear Dynamics of Reactor with Time Delay in Automatic Control System and Temperature Effect

Nonlinear Dynamics of Reactor with Time Delay in Automatic Control System and Temperature Effect

Turning points and sub- and supercritical bifurcations in a simple BWR model

Predictive Methods for Stability Margin in BWR

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