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Dykin, V. och Pázsit, I. (2009) *Remark on the role of the driving force in BWR instability*.

** BibTeX **

@article{

Dykin2009,

author={Dykin, Victor and Pázsit, Imre},

title={Remark on the role of the driving force in BWR instability},

journal={Annals of Nuclear Energy},

issn={0306-4549},

volume={36},

issue={10},

pages={1544–1552},

abstract={Simple models of BWR instability, used e.g. in understanding the role of the various oscillation modes in
the overall stability of the plant, assume that each oscillation mode can be described by a second order
system (a damped harmonic oscillator) driven by a white noise driving force. Change of the decay ratio
(DR) of the observed signal is, as a rule, associated with the changing of the parameters of the damped
oscillator, mainly its damping coefficient, and is interpreted in terms of the change of the stability of
the system. However, conceptually, one cannot exclude cases when the change of the response of a driven
damped oscillator is due to the change of the properties of the driving force. In this work we investigate
the effect of a non-white driving force on the behaviour of the system. A question of interest is how
changes of the spectrum of the driving force influence the observed autocorrelation function (ACF) of
the resulting signal. Hence we calculate the response of a damped harmonic oscillator driven by a
non-white driving force, corresponding to the reactivity effect of propagating density fluctuations in
two-phase flow. It is shown how in some special cases such a driving force, when interpreting the neutron
noise as if induced by a white noise driving source, can lead to an erroneous conclusion regarding the
stability of the system. It is also concluded that in the practically interesting cases the effect of the coloured
driving force, arising from propagating density fluctuations, is negligible.},

year={2009},

keywords={BWR stability, neutron noise, spectral density, autocorrelation, decay ratio},

}

** RefWorks **

RT Journal Article

SR Electronic

ID 98737

A1 Dykin, Victor

A1 Pázsit, Imre

T1 Remark on the role of the driving force in BWR instability

YR 2009

JF Annals of Nuclear Energy

SN 0306-4549

VO 36

IS 10

AB Simple models of BWR instability, used e.g. in understanding the role of the various oscillation modes in
the overall stability of the plant, assume that each oscillation mode can be described by a second order
system (a damped harmonic oscillator) driven by a white noise driving force. Change of the decay ratio
(DR) of the observed signal is, as a rule, associated with the changing of the parameters of the damped
oscillator, mainly its damping coefficient, and is interpreted in terms of the change of the stability of
the system. However, conceptually, one cannot exclude cases when the change of the response of a driven
damped oscillator is due to the change of the properties of the driving force. In this work we investigate
the effect of a non-white driving force on the behaviour of the system. A question of interest is how
changes of the spectrum of the driving force influence the observed autocorrelation function (ACF) of
the resulting signal. Hence we calculate the response of a damped harmonic oscillator driven by a
non-white driving force, corresponding to the reactivity effect of propagating density fluctuations in
two-phase flow. It is shown how in some special cases such a driving force, when interpreting the neutron
noise as if induced by a white noise driving source, can lead to an erroneous conclusion regarding the
stability of the system. It is also concluded that in the practically interesting cases the effect of the coloured
driving force, arising from propagating density fluctuations, is negligible.

LA eng

DO 10.1016/j.anucene.2009.07.015

LK http://dx.doi.org/10.1016/j.anucene.2009.07.015

OL 30