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Code Manual for CONTAIN 2.0 - Federation of American Scientists

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<strong>Code</strong> versions earlier than <strong>CONTAIN</strong> 1.2 use Equation (10-33) <strong>for</strong> the diffusivity, which does not<br />

take into account the composition <strong>of</strong> the noncondensable gas at all and which overestimates the ~<br />

diffusivity <strong>of</strong> steam in air at high temperatures. The old diffusivity model is still used in several<br />

specialized applications in the code: the DCH model (see Section 6.4.1 <strong>for</strong> discussion <strong>of</strong><br />

compensating effects that apply in this application), the SPARC model <strong>for</strong> aerosol scrubbing in<br />

suppression pools, and the models <strong>for</strong> aerosol dynamics.<br />

13.2.8 Engineered System Modeling<br />

The following list briefly summarizes the limitations <strong>for</strong> the three major ESF models: fan coolers,<br />

ice condensers, and sprays.<br />

Fan Cooler<br />

Ice Condenser<br />

Sprav Model<br />

a simple parametric model is provided in addition to the mechanistic condense<br />

model; if used, the simple model is plant-specific<br />

deposition <strong>of</strong> aerosols and fission products is not modeled in the simple model, and<br />

degradation <strong>of</strong> heat transfer surfaces by deposited aerosols is not considered in the<br />

more mechanistic model.<br />

temperature pr<strong>of</strong>ile in the ice is not represented<br />

nonuni<strong>for</strong>m melting <strong>of</strong> the ice is not modeled<br />

decay heating from deposited fission products is not modeled<br />

interaction <strong>of</strong> ice with debris in a DCH event is not modeled<br />

the atmosphere is assumed to be stagnant<br />

all spray droplets are assumed to be a single size within a given spray system<br />

interaction between spray drops are not modeled<br />

spray drop-to-drop interactions are ignored<br />

spray drops are not allowed to fall from one volume to another<br />

water in sprays is always pure despite its source<br />

sprays do not directly wet the containment walls<br />

radiation to the spray droplets is ignored<br />

sprays do not wash fission products <strong>of</strong>f walls<br />

The user may wish to model the upper region <strong>of</strong> the containment, where the spray nozzles are<br />

located, as a single cell, and subdivide the lower region into one or more cells. The spray model<br />

does not treat a spray falling from one cell into another cell or set <strong>of</strong> cells. If the spray carryover is<br />

perceived to be important in the lower region (e.g., with respect to aerosol scrubbing), this situation<br />

may be simulated by speci&ing a train <strong>of</strong> spray systems, using the pool <strong>for</strong> one to feed the next.<br />

Rev O 13 16 6/30/97

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