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Code Manual for CONTAIN 2.0 - Federation of American Scientists

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If boiling is occurring at the interface between the CORCON layer and the coolant pool and<br />

CORCON-Mod3 is active, the effects (discussed below) <strong>of</strong> gas barbotage (i.e., noncondensable gas ~<br />

injection at the interface) and coolant subcooling on film boiling heat transfer are included. If<br />

boiling is simply Occurnng between the coolant pool and a hot substrate not actively modeled with<br />

CORCON-Mod3, the effects <strong>of</strong> gas barbotage and subcooling on film boiling are not taken into<br />

account. Both gas barbotage and coolant subcooling can greatly increase the film boiling heat flux,<br />

while also increasing the Leidenfrost temperature at which the vapor film stabilizes.<br />

Gas barbotage increases film boiling heat transfer by increasing agitation <strong>of</strong> the coolant, and by<br />

increasing agitation <strong>of</strong> the melt surface. In CORCON-Mod3, the enhancement to the film boiling<br />

heat flux due to gas barbotage is included as a multiplicative factor. The factor used depends on<br />

whether the surface underlying the coolant is solid or liquid.<br />

If the surface underlying the coolant is liquid, then the enhancement is given by a correlation <strong>of</strong><br />

experimental results advanced by Greene. 1 The experimental results were <strong>for</strong> freon and water on<br />

three different molten metals, bismuth, lead, and Wood’s metal. The enhancement factor proposed<br />

by Greene is<br />

‘~=tin[ 1+1185[$10”’’(1 J~~51 (10-96)<br />

where Q; is the ratio <strong>of</strong> the measured heat flux to the heat flux calculated using the Berenson<br />

correlation given in Equation (10-93), jg”= jg/U., ~ is the superilcial gas velocity, U. is the terminal<br />

rise velocity <strong>of</strong> the noncondensable ga~ bubbles in the liquid metal, and Ja” is defined by<br />

Cp, AT,,,<br />

Ja* = 7<br />

hlv + ().5cp,ATmt<br />

where CP,Vis the specific heat <strong>of</strong> the vapor at constant pressure.<br />

(lo-97)<br />

If the surface underlying the coolant is solid, then the enhancement is given by a correlation<br />

advanced by Duignan. [Dui89] This correlation is based on experiments in which gas was injected<br />

through heated, drilled plates in contact with an overlying water pool. The enhancement factor used<br />

in CORCON-Mod3 is<br />

Q~* = 1 + 0.99 (N “~/Ja * “91<br />

‘G.A.Greene,BrookhavenNationalLaboratory,Upton,NY,privatecommunication, 1990.<br />

(10-98)<br />

10 48 6/30/97

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