Regular neutron noise diagnostics measurements at the Hungarian Paks NPP

Czibók, T.; Kiss, G.; Kiss, Sándor Z.; Krinizs, K.; Végh, János

doi:10.1016/s0149-1970(03)00007-6

Cited by 13 publications

(8 citation statements)

References 4 publications

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“…Moreover, out of phase relationship is found between opposite detectors and almost zero phase difference below 2 Hz between lower and upper detectors at the same radial position. In this last noise characteristic, it is possible to see linear phase relationship with a very low slope which indicates that the transport of the phenomenon is very fast [39,40].…”

Section: Results From the Simulated Scenariosmentioning

confidence: 99%

“…The results and conclusions obtained in this study are based on the use of analysis tools set, the so-called noise analysis techniques, that have been used for various purposes in nuclear reactor applications [26][27][28]. Sensor surveillance [29][30][31][32] and neutron noise analysis for core diagnostics [33,34] are two of the main applications of noise analysis techniques.…”

Section: Noise Analysis Techniquesmentioning

confidence: 99%

“…This is not observed in the previous scenarios of fuel elements vibration. The slope of the linear phase is proportional to the transit time according to [2,26] . This means that the higher the slope, the higher the transit time and therefore, the phenomenon of transportation is very slow.…”

Section: B Thermohydraulic Oscillations Scenariosmentioning

confidence: 99%

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Neutron noise analysis of simulated mechanical and thermal-hydraulic perturbations in a PWR core

Barrio-Parra

Chionis

Montalvo

et al. 2019

Annals of Nuclear Energy

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KWU-PWR plants show a high level of neutron noise that usually represents added problems in their operation. The frequency region of interest is below 1 Hz, so that thermohydraulic oscillations seem to be one of the main reasons behind. Nevertheless, recently, the neutron noise has experienced an increase in its normalized root mean square that coincide in time with the introduction of a new design of fuel assembly. This fact points out that there should be some relationship between neutron noise spectral characteristics and fuel assemblies' performance. In order to advance in understanding this phenomenon, the transient nodal code SIMULATE-3K (S3K) has been used to simulate mechanical vibrations of fuel assemblies and thermohydraulic oscillations of the core inlet flow. The simulated results obtained are neutron detectors signals which are analysed with noise analysis techniques and compared to real data.

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Section: Results From the Simulated Scenariosmentioning

confidence: 99%

Section: Noise Analysis Techniquesmentioning

confidence: 99%

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Neutron noise analysis of simulated mechanical and thermal-hydraulic perturbations in a PWR core

Barrio-Parra

Chionis

Montalvo

et al. 2019

Annals of Nuclear Energy

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“…It is known that the small changes in the reactor neutronics are linked to the evolution of thermal-hydraulic and mechanical processes. These links and relations between the neutron noise response and the thermal-hydraulic and mechanical processes have made neutron noise a matter of study for surveillance purposes and for detecting core flow anomalies (Czibók et al 2003;Hashemian 2006Hashemian , 2011Pázsit et al 2019;Runkel 1987). However, the cross and simultaneous feedbacks among these three types of processes make the identification of their relationships a quite complex problem to define.…”

Section: Neutron Noise In Kwu Reactorsmentioning

confidence: 99%

“…Its cause has been attributed to the vibrations of the fuel assemblies (Bermejo 2015;Dykin et al 2013Dykin et al , 2014Pázsit et al 2019;Runkel 1987). In the case of axial phase relationship analyses, when detectors in the same string are considered, we can appreciate transport phenomena in the frequency range below 1 Hz, where thermalhydraulic oscillations are the main contributor to the neutron noise (Bermejo 2015;Czibók et al 2003;Runkel 1987).…”

Section: Neutron Noise In Kwu Reactorsmentioning

confidence: 99%

Operational modal analysis for characterization of mechanical and thermal–hydraulic fluctuations in simulated neutron noise

Delgado

Verma

Montalvo

et al. 2021

Nuclear Engineering and Design

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In the study of the neutron noise in KWU pre-Konvoi PWRs, techniques, such as The Hilbert Huang Transform, but mainly traditional Fourier analysis is used widely to infer spectral characteristics, nevertheless these techniques exhibit important limitations in decomposing the signal so that we can distinguish the contribution of different phenomena (thermal-hydraulic and mechanical perturbations) in the same frequency range. Besides, there are difficulties to gather and present all the results in a single plot which shows the response of the core as a whole, making complex the data visualization. To overcome these limitations, an alternative methodology is researched, the so-called, Operational Modal Analysis (OMA), concretely the Frequency Domain Decomposition (FDD). This methodology is widely used in the study of the dynamic properties of systems and structures. The FDD was performed on a series of neutron noise signals from simulated scenarios based on the transient nodal code SIMULATE-3K. The simulations considered assume different sets of perturbation, from individual sources of fluctuations to combined sources. The methodology separates in the two first singular values and singular vectors the responses due to mechanical vibrations and thermal-hydraulic fluctuation in all the frequency range, in such a way that allows distinguishing different phenomena taking place at an equal frequency range as well as the increase of the response due to each phenomenon. The good performance of OMA in the present study provides promising possibilities to infer characteristics of the input excitation from the neutron noise data in PWR. Finally, the methodology shows remarkable advantages in the compilation of the results which can be utilized for monitoring purposes.

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Noise Techniques in Nuclear Systems

Pázsit¹,

Demazière²

2010

Handbook of Nuclear Engineering

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Regular neutron noise diagnostics measurements at the Hungarian Paks NPP

Cited by 13 publications

References 4 publications

Neutron noise analysis of simulated mechanical and thermal-hydraulic perturbations in a PWR core

Neutron noise analysis of simulated mechanical and thermal-hydraulic perturbations in a PWR core

Operational modal analysis for characterization of mechanical and thermal–hydraulic fluctuations in simulated neutron noise

Noise Techniques in Nuclear Systems

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