A Closed Counter-Current Two-Phase Thermosyphon Loop of a Cold Neutron Source in HANARO Research Reactor

Title & Authors
A Closed Counter-Current Two-Phase Thermosyphon Loop of a Cold Neutron Source in HANARO Research Reactor
Hwang, Kwon-Sang; Cho, Man-Soon; Sung, Hyung-Jin;

Abstract
An experimental study was carried out to delineate the flow characteristics in a closed countescurrent two-phase thermo syphon with concentric tubes. This is to be installed in the HANARO research reactor as a part of a Cold Neutron Source(CNS). In the present investigation, experiments ata room temperature with Freon-II3 as a moderator were performed. Results show that, based on the magnitude of pressure fluctuation, the flow regimes could be divided into 4 distinct ones in the ($\small{V_f,\;Q_i}$) plane, where $\small{V_f}$ represents the volume of the charged liquid and $\small{Q_i}$ the heat load: a stable flow regime, an oscillatory flow regime, a restablized flow regime and a dryout flow regime. For $\small{V_f}$>2.5l, the flow is stable at low $\small{Q_i}$. However, as $\small{Q_i}$ increases, the flow becomes oscillatory and finally restablizes As $\small{V_f}$ increases, the oscillation amplitude decreases, reaching to the restablized flow region at low $\small{Q_i}$, and the liquid level in the moderator cell remains high. In the oscillatory flow regimes, for a fixed VI; the oscillating period of time varies with $\small{Q_i}$, having a minimum value at a certain value of $\small{Q_i}$. The heat load, where the oscillating period of time is minimum, decreases as $\small{V_f}$ increases.
Keywords
Closed Thermosyphon;Counter-Current Two-Phase Flow;Cold Neutron Source(CNS);Flooding;Dryout;Stable Flow Regime;Oscillatory Flow Regime;Restabilized Flow Regime;
Language
Korean
Cited by
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