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3D thermal hydraulic simulation of the hot channel of a typical material testing reactor under normal operation conditions

3D thermohydraulische Simulation des Heißkanals eines typischen Reaktors zur Materialprüfung unter normalen Betriebsbedingungen
S. El-Din El-Morshedy and A. Salama
From the journal Kerntechnik

Abstract

The hot channel in a typical Material Testing Reactor (MTR) is subjected to 3D simulation. Because of the existence of similarity planes, only a quarter of the hot channel including meat thickness, clad, and coolant channel is considered for CFD analysis using the FLUENT code. For the simulation, steady state normal operation regime at the reactor nominal power is assumed. In order to build confidence in our modeling approach, the results obtained in this work are compared with those obtained from the one-dimensional simulation code, MTRTHA. That is, modified variables were generated in order to match those obtained by MTRTHA and to allow comparisons. Quite good agreement is generally observed, however, the maximum clad surface temperature predicted by the 3D calculations, located at the clad mid-width, is higher than the 1D prediction by about 8°C but still below the onset of subcooled boiling by adequate safety margin. The results show quite interesting 3D patterns in both the flow field and the heat transfer. Temperature profiles, velocity profiles and contours are all presented to highlight the essential 3D features of this system.

Kurzfassung

Der Heißkanal in einem typischen Materialprüfungsreaktor (MTR) wurde einer 3D Simulation unterzogen. Wegen des Vorhandenseins von ähnlicher Ebenen wird nur ein Viertel des Heißkanals inklusive Brennstoffgehalt, Hülle und Kühlkanal für die CFD Analyse mit Hilfe des FLUENT Code betrachtet. Für die Simulation werden normale Betriebsbedingungen im stationären Zustand bei nominaler Leistung des Reaktors angenommen. Zur Vertrauensbildung in Bezug auf den Modellansatz wurden die Ergebnisse mit denjenigen Ergebnissen verglichen, die mit Hilfe des eindimensionalen Simulationscodes MTRTHA erhalten wurden. Bei dieser Simulation werden veränderte Variablen erzeugt und an die von MTRTHA erhaltenen Werte angepasst um so Vergleiche zu erlauben. Generell wird eine gute Übereinstimmung beobachtet. Die durch die 3D Berechnungen vorhergesagte maximale Hüllentemperatur in der Mitte der Hülle ist um 8°C höher als die durch die 1D Berechnung vorhergesagte Temperatur, aber immer noch vor dem Einsetzen unterkühlten Siedens durch geeignete Sicherheitsspannen. Die Ergebnisse zeigen interessante 3D Muster, sowohl im Strömungsfeld als auch beim Wärmetransfer. Temperaturprofile, Geschwindigkeitsprofile und Konturen werden präsentiert, um die wesentlichen 3D Merkmale dieses Systems hervorzuheben.

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Received: 2010-5-17
Published Online: 2013-04-25
Published in Print: 2010-09-01

© 2010, Carl Hanser Verlag, München