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Code Manual for CONTAIN 2.0 - Federation of American Scientists

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The SRV model can treat unsubmerged discharges as well as submerged discharges. In<br />

unsubmerged discharges, the partitioning between pool and atmosphere is handled through a coolant<br />

phase separation calculation. In this calculation the source materials are assumed to expand<br />

isenthalpically down to the cell pressure be<strong>for</strong>e mixing with the cell. Any liquid coolant present at<br />

the end <strong>of</strong> expansion is diverted to the pool, and all other materials are directed to the atmosphere.<br />

In contrast, partitioning is not considered <strong>for</strong> atmosphere sources. All materials are simply directed<br />

to the atmosphere.<br />

The modeling <strong>of</strong> suppression pool vents is discussed in more detail in Section 11.1, and the SRV<br />

modeling is discussed in more detail in Section 11.2. The input <strong>for</strong> the ordinary flow paths is<br />

discussed in Section 14.2.4 and that <strong>for</strong> the dedicated suppression pool vent model is discussed in<br />

Section 14.2.4.3. The SRV input is discussed in Section 14.3.4.<br />

2.12 Engineered Safetv Features<br />

Three major engineered safety features (ESFS) are modeled: fan coolers, ice condensers, and<br />

containment sprays. Associated with these models is a liquid transport system that provides sources<br />

and sinks <strong>for</strong> the ESFS and also allows coolant transfer between lower cell pools to be modeled. The<br />

components available <strong>for</strong> such systems include tanks, pumps, orifices, pipes, valves, and heat<br />

exchangers, as well as user-specified external sources <strong>of</strong> coolant. In addition, the ovefflow <strong>of</strong><br />

coolant from one pool to another can be modeled. The status <strong>of</strong> models <strong>for</strong> the removal <strong>of</strong><br />

suspended aerosols and fission products, as a result <strong>of</strong> ESF operation, is indicated below.<br />

Fan Coo ler. Fan coolers provide nonemergency cooling and augment the heat removal capabilities<br />

<strong>of</strong> the sprays. These coolers use large-capacity fans in conjunction with banks <strong>of</strong> finned,<br />

service-water-cooled coils to cool the containment atmosphere. Two types <strong>of</strong> fan cooler models are<br />

available. The fmt model is similar to that developed <strong>for</strong> the MARCH code. ~oo83] It is simple<br />

and fast, and it adequately reproduces the cooling capacity <strong>of</strong> actual plant equipment under saturated<br />

conditions. It can be used whenever the effects <strong>of</strong> superheated conditions are expected to be<br />

relatively minor.<br />

A second, more mechanistic, fan cooler model is based on <strong>for</strong>ced convective heat transfer<br />

correlations similar to those used throughout the code. This model calculates mass and heat transfer<br />

coefficients based on the atmosphere and coil conditions and can treat superheated conditions.<br />

However, it requires a more detailed knowledge <strong>of</strong> fan cooler characteristics than the simple model<br />

described above. These two fan cooler models are discussed in more detail in Section 12.1, and the<br />

input <strong>for</strong> the models is discussed in Section 14.3.3.2.<br />

Because <strong>of</strong> the relatively cool surfaces and high condensation rates provided by fan coolers,<br />

substantial deposition <strong>of</strong> aerosols can occur. The aerosol removal resulting from diffusiophoresis<br />

is calculated if the mechanistic fan cooler model is used. This modeling is discussed in Section 7.4.<br />

Ice Co ndenser. Ice condensers are used in some PWR containment systems to limit containment<br />

overpressure in the event <strong>of</strong> a loss-<strong>of</strong>-coolant accident by directing the steam released from the<br />

Rev O 2-23 6/30/97

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