10.08.2013 Views

Code Manual for CONTAIN 2.0 - Federation of American Scientists

Code Manual for CONTAIN 2.0 - Federation of American Scientists

Code Manual for CONTAIN 2.0 - Federation of American Scientists

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

By default this diameter is not defined, thus the model is not active. A diameter must be specified<br />

by the user in a given DCH-CELL input block using the DIATR4P keyword to enable non-airborne ~<br />

debris interactions in that cell. The DIATRAP keyword maybe used either by itself to speci~ a<br />

constant diameter or within the VAR-PARM block to specify a time-dependent diameter. For a<br />

given effective diameter, the debris surface area is computed according to the relation<br />

‘DCH<br />

6 x ‘nad,i,k<br />

Anadi = k<br />

pn,@i‘n=d,i<br />

(6-160)<br />

where &,i is the surface area <strong>for</strong> the non-airborne field in cell i, ~~~j,~is the mass <strong>of</strong> debris species<br />

kin the non-airborne field in cell i, pnad,i is the average material density <strong>of</strong> debris in the non-airborne<br />

field in cell i, and dn,~,is the user-specified effective diameter <strong>for</strong> the non-airborne field in cell i.<br />

The mass <strong>of</strong> non-airborne debris is governed by the rate <strong>of</strong> debris addition to the non-airborne debris<br />

field, the rate <strong>of</strong> entrainment from the non-airborne debris field, and the trapping rate <strong>of</strong> debris into<br />

the non-tiborne debris field. Equation (6-78) in Section 6.3.1 gives the governing equation <strong>for</strong> the<br />

mass <strong>of</strong> debris in the non-a.hbome field that takes into account these three processes. The addition<br />

<strong>of</strong> debris to the non-airborne field and the entrainment <strong>of</strong> debris out <strong>of</strong> the non-airborne field is<br />

governed by user-specified tables or the RPV models as noted above.<br />

The average material density <strong>of</strong> the non-airborne debris is calculated as the inverse <strong>of</strong> the mass ~<br />

average <strong>of</strong> specific volume <strong>of</strong> all materials in the trapped field at the temperature <strong>of</strong> the trapped field.<br />

Normally the densities are taken from the material property tables given in the USERDAT input, but<br />

they will be ignored if the DENDRP global input (or VAR-PARM table) is specified, in which case<br />

the average density <strong>of</strong> airborne and non-airborne debris will be set to the specified value.<br />

The second unique aspect <strong>of</strong> non-airborne debris heat transfer is that heat transfer to structures or<br />

the ice surfaces in an ice condenser cell is not modeled <strong>for</strong> debris that is not airborne. There<strong>for</strong>e, the<br />

non-airborne field is not included in the debris to surface heat transfer calculation. The third<br />

difference is that the black body multiplier <strong>for</strong> debris to gas radiation can be specified separately <strong>for</strong><br />

non-airborne debris. This is done using the RADTRAP keyword. By default this value is equal to<br />

the value <strong>of</strong> e~,~that is used <strong>for</strong> the airborne debris fields.<br />

The fourth and final difference <strong>for</strong> non-airborne debris is that if VELTRAP is not specified and<br />

fewer than two structures are defined in the cell, an average gas velocity through the cell is used <strong>for</strong><br />

heat and mass transfer <strong>for</strong> non-airborne debris. This average is calculated by using the current cell<br />

gas volume to the two-thirds power <strong>for</strong> the cell hydraulic area. If VELTR4P is not specified and two<br />

or more structures are defined in the cell, then the <strong>for</strong>ced convective velocity defined <strong>for</strong> the second<br />

structure is used (see Sections 10.1.1.6, 13.3.2.2.2, and 14.3.1.3). This is in contrast to airborne<br />

debris, where the trapping conditions and the gas and debris flow velocities are used to calculate an<br />

appropriate velocity <strong>for</strong> heat transfer as described in Section 6.3.2. This is not done <strong>for</strong> non-airborne<br />

debris since this field is not flowing and is not subject to trapping as are the airborne debris fields.<br />

R O 666

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!