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Code Manual for CONTAIN 2.0 - Federation of American Scientists

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Levy<br />

Tutu-Ginsberg<br />

Tutu<br />

Table 13-2<br />

I& Values and Per<strong>for</strong>mance Statistics <strong>for</strong> Cavity Correlations<br />

BNL (1/42 Scale) SNL (1/10 Scale)<br />

Correlation Surry Zion Surry Zion<br />

K 0.57 0.8 0.048 0.0073<br />

...........................................................................................................................................<br />

oest 0.176 0.125 0.144 0.123<br />

K 1 1 0.6 0.47<br />

.............................................................................................................................................<br />

Gest 0.102 0.088 0.103 0.153<br />

& 5.3 16 1.25 0.4<br />

...........................................................................................................................................<br />

Gest 0.115 0.184 0.191 0.103<br />

& 100 130 118 43<br />

Modified Whallev-Hewitt .............................................................................................................................................<br />

In the meantime, it is up to the user to select a value <strong>of</strong> I& that yields reasonable results. In assessing<br />

whether a result is reasonable, the two most important features to keep in mind are the fraction <strong>of</strong><br />

the debris that is dispersed (F~)and the length <strong>of</strong> time during which significant amounts <strong>of</strong> debris ~<br />

are being dispersed. Short dispersal times imply minimal opportunity <strong>for</strong> debris to interact with<br />

blowdown steam and, hence, choosing a large value <strong>of</strong> ~ resulting in everything being quickly<br />

blown out <strong>of</strong> the cavity can be nonconservative.<br />

In judging whether the calculated debris dispersal rate is “reasonable,” it maybe helpful to derive<br />

an estimate <strong>of</strong> the coherence ratio ~ from the calculation and compare it with the value predicted<br />

by the empirical model <strong>of</strong> Equation (13-4). In order to estimate the coherence ratio <strong>for</strong> the<br />

calculation, one may f~st estimate the time te at which dispersal is effectively complete in the<br />

calculation; this may be taken to be the time at which the amount <strong>of</strong> debris dispersed from the cavity<br />

reaches 95910<strong>of</strong> its final value. It is best to base the estimate <strong>of</strong>t. upon a component <strong>of</strong> the debris<br />

which is neither produced nor consumed by chemical reactions, such as UOZ. The calculated RPV<br />

pressure at time temay then be equated to Pwv,~and used in Equation (13-3) to define the value <strong>of</strong><br />

~ corresponding to the calculation. If this value is much smaller than the value given by Equation<br />

(13-4), it is likely that I& (CCENR) should be increased; and conversely. While results cited in<br />

Reference Wi195 suggest that sensitivity <strong>of</strong> DCH loads to the coherence ratio is <strong>of</strong>ten quite moderate,<br />

experience to date is insul%cient to guarantee this will always be the case. Hence sensitivity studies<br />

in which the coherence is varied (by varying CCENR) are recommended until it is established that<br />

sensitivity is low <strong>for</strong> the class <strong>of</strong> problems being considered.<br />

Even in the context <strong>of</strong> the experiments with cold simulants, the values <strong>of</strong> I&obtained are meaningful<br />

only <strong>for</strong> the particular cavity geometric parameters assumed in the assessments described in Williams<br />

Rev O 13 54 6/30/97

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