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Heat transfer study of a submerged reactor channel under boil-off condition

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Published/Copyright: May 18, 2013
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Abstract

Experiments have been carried out to study the heatup behavior of a single segmented reactor channel for Pressurized Heavy Water Reactor under submerged, partially submerged and exposed conditions. This situation may arise from a severe accident scenario of Pressurised Heavy Water Reactors where full or segmented reactor channels are likely to be disassembled and form a submerged debris bed. An assembly of electrical heater rod, simulating fuel bundle and channel components like Pressure Tube and Calandria Tube constitutes the segmented reactor channel. Heatup of this assembly is observed with respect to different water levels ranging from full submergence to totally exposed and power levels of 6–8 kW, typical to decay power level. It has been observed from the set of experiment that fuel bundle local dry out followed by heatup does not happen till the bundle is partially submerged. Temperature excursion of the bundle is evident when the bundle is exposed to steam-air environment.

Kurzfassung

Für einen einzelnen Reaktorkanal eines schwerwassermoderierten Druckreaktor (PHWR) wurden Experimente zur Untersuchung des Aufheizverhaltens dieses Kanals unter den drei während eines schweren Störfallszenariums möglichen Bedingungen vollständig überflutet, teilweise überflutet und freiliegend. Im Experiment wird das Brennelementsegment durch elektrische Heizstäbe zur Simulation des Brennelements und der Komponenten Druckrohr und Calandriarohr nachgebildet. Das Aufheizverhalten wird bei verschiedenen Wasserständen von vollkommen freiliegend bis vollkommen überflutet untersucht. Dabei werden typische Nachzerfallsleistungen zwischen 6 und 8 kW aufgebracht. So wurde experimentell festgestellt, dass das lokale Austrocknen des Brennelements infolge der Aufheizung nicht auftritt, solange das Bündel zumindest teilweise überflutet ist. Sobald das Bündel einer Wasserdampf-Luft-Umgebung ausgesetzt ist, findet erwartungsgemäß eine Temperaturanstieg statt.

References

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Received: 2012-7-20
Published Online: 2013-05-18
Published in Print: 2012-12-01

© 2012, Carl Hanser Verlag, München

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