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**Harvard**

Lange, C., Hennig, D., Hurtado, A., Dykin, V. och Demazière, C. (2012) *Comments on local power oscillation phenomenon at BWRs*.

** BibTeX **

@article{

Lange2012,

author={Lange, Carsten and Hennig, Dieter and Hurtado, Antonio and Dykin, Victor and Demazière, Christophe},

title={Comments on local power oscillation phenomenon at BWRs},

journal={Progress in Nuclear Energy},

issn={0149-1970},

volume={60},

pages={73-88},

abstract={Under the framework of BWR stability analysis, local neutron-flux oscillation events have attracted the attention of a number of researchers. In 1996, an unusual instability event occurred at Forsmark-1 in which an irregular oscillation pattern with highly localized, relatively large-amplitude oscillations were measured. Some authors assumed that this behaviour was caused by the superposition of stable spatial mode limit cycle oscillations, where the BWR core as a neutron kinetics/-thermal-hydraulic coupled system is unstable. Subsequent time-series analysis of the local power range monitor (LPRM) signals resulted in a space-dependent decay ratio, an inexplicable result. Furthermore, noise analysis-based localization techniques pointed towards the existence of two strong “perturbation sources” in one of the two halves of the core, one of them coinciding with the radial position of an unseated bundle. In the scope of theoretical work, the possibility of a space-dependent decay ratio was discussed but not comprehensively understood. Motivated by these findings, the effect of local neutron-flux oscillations on the stability behaviour of BWR is discussed, and one possible interpretation is proposed which is able to explain the space-dependent decay ratio as well as the long term oscillation pattern. The RAM–ROM method is applied to a Forsmark measurement case, where an irregular oscillation pattern was found and to an operational point (KKB-B8) of NPP Brunsbüttel, where a local neutron-flux oscillation is superimposed on an unstable global power oscillation. The effect of the local neutron flux oscillating sources on the space- and time-dependent neutron field is described by a rigorous application of the mode expansion approach. The consequences to signal analysis are then discussed. It will be pointed out in the paper that when a BWR system is stable with regards to power oscillations but is driven by local neutron-flux oscillating sources, the decay ratio does not indicate the real BWR stability behaviour.},

year={2012},

keywords={BWR, stability, nuclear reactor dynamics},

}

** RefWorks **

RT Journal Article

SR Electronic

ID 161503

A1 Lange, Carsten

A1 Hennig, Dieter

A1 Hurtado, Antonio

A1 Dykin, Victor

A1 Demazière, Christophe

T1 Comments on local power oscillation phenomenon at BWRs

YR 2012

JF Progress in Nuclear Energy

SN 0149-1970

VO 60

SP 73

OP 88

AB Under the framework of BWR stability analysis, local neutron-flux oscillation events have attracted the attention of a number of researchers. In 1996, an unusual instability event occurred at Forsmark-1 in which an irregular oscillation pattern with highly localized, relatively large-amplitude oscillations were measured. Some authors assumed that this behaviour was caused by the superposition of stable spatial mode limit cycle oscillations, where the BWR core as a neutron kinetics/-thermal-hydraulic coupled system is unstable. Subsequent time-series analysis of the local power range monitor (LPRM) signals resulted in a space-dependent decay ratio, an inexplicable result. Furthermore, noise analysis-based localization techniques pointed towards the existence of two strong “perturbation sources” in one of the two halves of the core, one of them coinciding with the radial position of an unseated bundle. In the scope of theoretical work, the possibility of a space-dependent decay ratio was discussed but not comprehensively understood. Motivated by these findings, the effect of local neutron-flux oscillations on the stability behaviour of BWR is discussed, and one possible interpretation is proposed which is able to explain the space-dependent decay ratio as well as the long term oscillation pattern. The RAM–ROM method is applied to a Forsmark measurement case, where an irregular oscillation pattern was found and to an operational point (KKB-B8) of NPP Brunsbüttel, where a local neutron-flux oscillation is superimposed on an unstable global power oscillation. The effect of the local neutron flux oscillating sources on the space- and time-dependent neutron field is described by a rigorous application of the mode expansion approach. The consequences to signal analysis are then discussed. It will be pointed out in the paper that when a BWR system is stable with regards to power oscillations but is driven by local neutron-flux oscillating sources, the decay ratio does not indicate the real BWR stability behaviour.

LA eng

DO 10.1016/j.pnucene.2012.04.008

LK http://dx.doi.org/10.1016/j.pnucene.2012.04.008

OL 30