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Title: Effect of boiling regime on melt stream breakup in water

A study has been performed examining the breakup and mixing behavior of an initially coherent stream of high-density melt as it flows downward through water. This work has application to the quenching of molten core materials as they drain downward during a postulated severe reactor accident. The study has included examination of various models of breakup distances based upon interfacial instabilities dominated either by liquid-liquid contact or by liquid-vapor contact. A series of experiments was performed to provide a data base for assessment of the various modeling approaches. The experiments involved Wood's metal (T/sub m/ = 73/sup 0/C, rho = 9.2 g/cm/sup 3/, d/sub j/ = 20 mm) poured into a deep pool of water. The temperature of the water and wood's metal were varied to span the range from single-phase, liquid-liquid contact to the film boiling regime. Experiment results showed that breakup occurred largely as a result of the spreading and entrainment from the leading edge of the jet. However, for streams of sufficient lengths a breakup length could be discerned at which there was no longer a coherent central core of the jet to feed the leading edge region. The erosion of the vertical trailing column is bymore » Kelvin-Helmoltz instabilities and related disengagement of droplets from the jet into the surrounding fluid. For conditions of liquid-liquid contact, the breakup length has been found to be about 20 jet diameters; when substantial vapor is produced at the interface due to heat transfer from the jet to the water, the breakup distance was found to range to as high as 50 jet diameters. The former values are close to the analytical prediction of Taylor, whereas the latter values are better predicted by the model of Epstein and Fauske.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
6782053
Report Number(s):
CONF-861204-6
ON: DE87004705
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: 4. Miami international symposium on multi-phase transport and particulate phenomena, Miami Beach, FL, USA, 15 Dec 1986; Other Information: Microfiche only, copy does not permit paper copy reproduction
Research Org:
Argonne National Lab., IL (USA)
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; BWR TYPE REACTORS; MELTDOWN; MOLTEN METAL-WATER REACTIONS; PWR TYPE REACTORS; BOILING; CORIUM; FLUID FLOW; HEAT TRANSFER; HYDRAULICS; QUENCHING; ACCIDENTS; ENERGY TRANSFER; FLUID MECHANICS; MECHANICS; PHASE TRANSFORMATIONS; REACTOR ACCIDENTS; REACTORS; WATER COOLED REACTORS; WATER MODERATED REACTORS 220900* -- Nuclear Reactor Technology-- Reactor Safety; 210100 -- Power Reactors, Nonbreeding, Light-Water Moderated, Boiling Water Cooled; 210200 -- Power Reactors, Nonbreeding, Light-Water Moderated, Nonboiling Water Cooled