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ISSN Imprimir: 1064-2285
ISSN On-line: 2162-6561
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Liquid-Metal Coolant Boiling in Cooling Channel Simulators
RESUMO
In cooling channels with "hot spots", oscillations of the main thermohydraulic parameters of the liquid-metal coolant can appear. To avoid these oscillations is important, to ensure nuclear power plant safety. An experimental study of oscillations of mass flow rate, pressure and temperature was conducted using annular cooling channels simulators. These simulators were installed in a circulating loop, which was cooled by a liquid-metal alloy of 22% Na and 78% K by mass. The heat flux density varied from 10 to 350 W/cm2 with the pressures up to 0.2 MPa and above 1.0 MPa, respectively. The effect of a spacing wire coil on the coolant boiling was investigated. In a special test rig, the effect of hydrogen dissolved in the liquid metal on the heat-transfer surface superheat was studied, as well. Regarding the reliability of heat removal, incipient unsteady slug-flow boiling appears to be the most dangerous. The maximum superheat reached 146deg;C. In an eccentric annular channel, the coolant boiling on "hot spots" decreases the azimuth temperature nonuniformity by more than two times.