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Code Manual for CONTAIN 2.0 - Federation of American Scientists

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a~ =1-<br />

—NFr<br />

D<br />

(6-25)<br />

and N = 0.6. The single-phase liquid flow rate W,l is given by Equation (6-22), and the single-phase<br />

gas flow rate is determined from<br />

(6-26)<br />

where rn~ is the mass flow rate <strong>of</strong> gas out <strong>of</strong> the RPV and A~ is the area <strong>for</strong> gas flow in the RPV<br />

hole. The gas void fraction is used to determine the rate at which debris exits the RPV cell during<br />

the two-phase portion <strong>of</strong> the high pressure melt ejection, and further discussion is provided in the<br />

next section. As in single-phase debris discharge, debris that exits the RPV cell is removed from the<br />

trapped debris bin in the RPV cell and placed in the trapped debris bin in the cavity cell.<br />

6.2.9.2.3 Gas Flow Area and Debris Flow Rate. The gas flow area in the hole in the RPV during<br />

two-phase discharge can be determined from the gas exit quality using the relationship<br />

A~ = a~ Ah (6-27) ~<br />

The mass flow rate <strong>of</strong> debris out <strong>of</strong> the RPV during two-phase discharge can be expressed as<br />

‘nd=[pdAhcd~][AhihA<br />

(6-28)<br />

6.2.9.3 Vessel Hole Ablation. The hole in the RPV is enlarged through ablation <strong>of</strong> the vessel wall<br />

by debris as it exits the RPV. The hole ablation rate is given by the relation ~i194a]<br />

ddh<br />

—=<br />

2K~hd~AT,<br />

dt Pw[cp,w ~mp,w - ‘w) + ‘f,w]<br />

(6-29)<br />

where I& is a constant multiplier to the ablation rate specified in ARMULT, AT~is the difference<br />

between the temperature <strong>of</strong> the debris in the RPV and the melting temperature <strong>of</strong> the RPV wall as<br />

specified by TMELT, pWis the density <strong>of</strong> the RPV wall as specified by RHOWAL, CP,Wis the specific<br />

heat <strong>of</strong> the RPV wall as specified by CPWALL, T.P,Wis the melting temperature <strong>of</strong> the RPV<br />

wall as specified by TMELT, TWis the temperature <strong>of</strong> the RPV wall as specified by TWALL, and<br />

~,w is the heat <strong>of</strong> fusion <strong>of</strong> the RPV wall as specified by HFWALL.<br />

Rev. O 6-20 6/30/97

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