Thermal-hydraulic modeling of the onset of flow instability in MTR reactors
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H. A. Khater
Abstract
Prediction of the onset of the flow instability (OFI) in steady and transient sub-cooled flow boiling is an important consideration in the design and operation of nuclear reactors especially material test reactors (MTR). In this study, a predictive model of OFI in the MTR has been developed. The model is based on both heat balance of bubble generation and condensation and force balance for the detached bubbles at the onset of significant void (OSV). Only one coefficient involved in the proposed model is identified by experimental data that covers the wide range of MTR operating conditions. The model results are compared with results of some previous models where the present model gives the lower deviation from the experimental data. A correlation for the heat flux at OFI is also developed based on the present model. The developed correlation gives lower deviation from the experimental data than the well-known correlation of Whittle and Forgan. The model is also used to predict the OFI locus during transient where it shows good agreement with the short transient of Lee and Bankoff as well.
Kurzfassung
Die Vorhersage der Entstehung von Strömungsinstabilitäten (OFI) bei stabilen und transienten unterkühlten Siedeströmungen ist ein wichtiger Aspekt bei der Entwicklung und beim Betrieb von Kernreaktoren, insbesondere bei Materialtest-Reaktoren (MTR). In der vorliegenden Arbeit wird ein OFI-Vorhersagemodell entwickelt. Das Modell berücksichtigt sowohl die Wärmebilanz der Blasenbildung und der Kondensation wie auch die Energiebilanz einzelner Dampfblasen beim Entstehen eines signifikanten Void-Effekts (OSV). Nur ein in diesem Modell betrachteter Koeffizient, der den breiten Bereich der MTR-Betriebsphasen umfasst, wurde experimentell bestimmt. Die Modellergebnisse werden verglichen mit den Ergebnissen der Vorläufer-Modelle, wobei das jetzige Modell eine kleinere Abweichung von den experimentellen Werten aufweist. Auf der Basis dieses Modells wurde ebenfalls die Korrelation des Wärmestroms zur Entstehung von Strömungsinstabilitäten betrachtet. Diese ergab niedrigere Abweichungen von den experimentellen Daten als die bekannte Korrelation von Whittle und Forgan. Das Modell wird auch verwendet zur Vorhersage der OFI Lokalisierung transienter Vorgänge und zeigt eine gute Übereinstimmung mit den kurzzeitigen Transienten von Lee und Bankoff.
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© 2006, Carl Hanser Verlag, München
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Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Minor actinide burning in a CANDU thorium reactor
- Modeling of the TOSQAN test facility with the lumped parameter code COCOSYS
- Thermal-hydraulic modeling of the onset of flow instability in MTR reactors
- 10.3139/124.100302
- 10.3139/124.100304
- Radiation transfer in inhomogeneous exponential media
- Neutron transport problems for extremely anisotropic scattering
- Milne problem for isotropic and linearly anisotropic scattering for specular and diffuse reflecting boundary conditions solved with the HN method
- ICDE-results on complete common cause failures in the light of results obtained with the POS model
- Modelling of the cumulative behaviour of Caesium and Strontium activities in nuclear fuel
- Analytical study of the closure flow inside the ETRR-2 core chimney
- Minimizing radiation exposure for the reactor staff during the dismantling of a TRIGA research reactor
