Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter May 18, 2013

Analytical investigation of the properties of the neutron noise induced by vibrating absorber and fuel rods

Analytische Untersuchung der Eigenschaften des Neutronenrauschens durch vibrierende Absorber und Brennstäbe
A. Jonsson, H. N. Tran, V. Dykin and I. Pázsit
From the journal Kerntechnik

Abstract

Analytical solution methods for the neutron noise in a one-dimensional multi-region system in two-group theory, which have so far been based on the adjoint function technique, are extended here to using the forward Green's function technique. The forward Green's functions were calculated analytically for a noise source in a core surrounded by reflector regions at both sides. It is shown that with symbolic computation methods, the forward Green's function can be used for the calculation of the space- and frequency-dependent noise in the first order approximation for arbitrary noise sources which have an analytical representation. The properties of the induced neutron noise were investigated for vibrations of both absorbers and fuel assemblies, with two representations of the noise sources: a point-like source which corresponds to the vibrations of a fuel rod, and a finite width source which corresponds to vibrations of a fuel assembly. The contributions of the components induced by the fluctuations of the various types of macroscopic cross sections in the total noise are also discussed and the information content of the noise in the fast group is explored for the identification of fuel assembly vibrations.

Kurzfassung

Analytische Lösungsmethoden für das Neutronenrauschen in eindimensionalen multi-regionalen Systemen in der Zwei-Gruppentheorie, die bisher auf der Methode der adjungierten Funktionen basierten, werden hier erweitert durch Anwendung vorwärts gerichteter Greenfunktionen. Diese wurden analytisch berechnet für eine Rauschquelle in einem Kern umgeben von Reflektorregionen. Es wird gezeigt, dass mit symbolischen Rechenmethoden, die vorwärts gerichtete Greenfunktion zur Berechnung des orts- und frequenzabhängigen Rauschens in erster Näherung für willkürliche Rauschquellen verwendet werden können. Die Eigenschaften des induzierten Neutronenrauschens wurden untersucht auf Vibrationen sowohl der Absorber wie auch der Brennelementanordnungen mit zwei verschiedenen Darstellungen der Rauschquellen: einer punktförmigen Quelle, die den Vibrationen eines Brennstabs entspricht, und einer Quelle endlicher Weite, die Vibrationen einer Brennelementanordnung entspricht. Die Beiträge der Komponenten, die durch Fluktuationen verschiedener Arten von makroskopischen Wirkungsquerschnitten im Gesamtrauschen induziert wurden werden ebenfalls diskutiert. Der Informationsgehalt des Rauschens in der schnellen Gruppe wird untersucht zur Identifizierung der Vibrationen der Brennelementanordnung.

References

1 Thie, J. A.: Power reactor noise, American Nuclear Society, 1981Search in Google Scholar

2 Williams, M. M. R.: Random Processes in Nuclear Reactors. Pergamon Press, Oxford, 1974Search in Google Scholar

3 Pázsit, I. andDemazière, C.: Noise Techniques in Nuclear Systems. Handbook of Nuclear Engineering, Ed.D. G.Cacuci, Vol. 3, Chapter 2. Springer Verlag, 201010.1007/978-0-387-98149-9_14Search in Google Scholar

4 Pázsit, I. andLux, I.: Some aspects of the use and calculation of the dynamic adjoint function in multi-region systems: The inhomogeneous response matrix method. Kernenergie26 (1983) 143Search in Google Scholar

5 Pázsit, I.: Dynamic transfer function calculations for core diagnostics. Annals of Nuclear Energy19 (1992) 30331210.1016/0306-4549(92)90023-5Search in Google Scholar

6 Pázsit, I.: Hugo van Dam and the dynamic adjoint function. Annals of Nuclear Energy30 (2003) 1757177510.1016/S0306-4549(03)00140-3Search in Google Scholar

7 Pázsit, I.: Two-group theory of noise in reflected reactors with application to vibrating absorbers. Annals of Nuclear Energy5 (1978) 18519610.1016/0306-4549(78)90005-1Search in Google Scholar

8 Wolfram Research Inc., Mathematica, Version 8, Champaign, IL, http://wolfram.com/, 2012Search in Google Scholar

9 Williams, M. M. R.: Reactivity changes due to the random vibration of control rods and fuel elements. Nuclear Science and Engineering39 (1970) 144Search in Google Scholar

10 Pázsit, I.: Investigation of the space-dependent noise induced by a vibrating absorber: Atomkernenergie30 (1977) 29Search in Google Scholar

11 Kosály, G. andWilliams, M. M. R.: Point theory of the neutron noise induced by inlet temperature fluctuations and random mechanical vibrations. Atomkernenergie18 (1971) 203Search in Google Scholar

12 Pázsit, I.: Control rod models and vibration induced noise. Annals of Nuclear Energy15 (1988) 33334610.1016/0306-4549(88)90081-3Search in Google Scholar

13 Pázsit, I. andGaris, N. S.: Numerical investigation of two control rod models for vibration noise in two dimensions. Progress of Nuclear Energy29 (1995) 24726310.1016/0149-1970(95)00013-ASearch in Google Scholar

14 Dykin, V.;Jonsson, A. andPázsit, I.: Qualitative and quantitative investigation of the propagation noise in various reactor systems Submitted to Progress of Nuclear Energy, 2012Search in Google Scholar

15 Dykin, V. andPázsit, I.: Some curious properties of the reactor noise in simple systems To be submitted to Nuclear Science and Engineering, 2012Search in Google Scholar

Received: 2012-04-16
Published Online: 2013-05-18
Published in Print: 2012-11-01

© 2012, Carl Hanser Verlag, München