Prediction, analysis and solution of flow inversion phenomenon in a typical MTR reactor with upward core cooling

S. El-Din El-Morshedy

doi:10.3139/124.110110

Article

Prediction, analysis and solution of flow inversion phenomenon in a typical MTR reactor with upward core cooling

S. El-Din El-Morshedy

Published/Copyright: May 5, 2013

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From the journal Kerntechnik Volume 75 Issue 6

Abstract

Research reactors of power greater than 20 MW are usually designed to be cooled with upward coolant flow direction inside the reactor core. This is mainly to prevent flow inversion problems following a pump coast down. However, in some designs and under certain operating conditions, flow inversion phenomenon is predicted. In the present work, the best-estimate Material Testing Reactors Thermal-Hydraulic Analysis program (MTRTHA) is used to simulate a typical MTR reactor behavior with upward cooling under a hypothetical case of loss of off-site power. The flow inversion phenomenon is predicted under certain decay heat and/or pool temperature values below the design values. The reactor simulation under loss of off-site power is performed for two cases namely; two-flap valves open and one flap-valve fails to open. The model results for the flow inversion phenomenon prediction is analyzed and a solution of the problem is suggested.

Kurzfassung

Forschungsreaktoren mit einer Leistung von mehr als 20 MW sind meist so aufgebaut, dass das Kühlmittel im Reaktorkern aufwärts strömt. Dies dient hauptsächlich der Vermeidung von Strömungsinversionsphänomenen nach dem Auslaufen einer Pumpe. Bei einigen Anordnungen und unter bestimmten Betriebsbedingungen werden jedoch Strömungsinversionsphänomene vorhergesagt. In der vorliegenden Arbeit wird das Analyseprogramm MTRTHA verwendet, um das Verhalten eines typischen Materialprüfungsreaktors zu simulieren mit aufwärts strömendem Kühlmittel im hypothetischen Fall eines Ausfalls der Stromversorgung. Das Strömungsinversionsphänomen wird vorhergesagt für bestimmte Werte der Restwärme und der Pool-temperatur, die unterhalb der Auslegungswerte liegen. Die Simulation wird für zwei Fälle durchgeführt: zwei Klappenventile öffnen und ein Klappenventil öffnet nicht. Die Rechenergebnisse für die Vorhersage der Strömungsinversionsphänomene werden analysiert und eine Lösung des Problems wird vorgeschlagen.

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Received: 2010-7-28

Published Online: 2013-05-05

Published in Print: 2010-11-01

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https://doi.org/10.3139/124.110110