Code Manual for CONTAIN 2.0 - Federation of American Scientists

A number of reference elevations are also used for the lower cell repositories in a given cell,
depending on the material and whether a transfer is involved. With the exception of liquid coolant ~
and gases and aerosols directed to and from the coolant pool, the reference elevation for computing
the gravitational potential energy for a lower cell repository is the cell-bottom elevation. For
transfers of liquid coolant to and from the pool, the reference elevation is taken to be the pool surface
elevation, computed on the basis of the cell-bottom elevation, the pool cross-sectional area, and the
pool coolant density. For purposes of calculating. the repository potential energy of the pool coolant,
the reference elevation is the pool-center elevation. With respect to gases and aerosols introduced
into the pool through flow path or the boiling water reactor safety relief valve or suppression vent
models, the reference elevation for the point of introduction is given by the injection height above
cell bottom. With respect to gases and aerosols introduced into the pool through core-concrete
interactions modeled by CORCON, the reference elevation for the point of introduction is the cellbottom
elevation. The reference elevation for the point of departure from the pool of gases and
aerosols is the pool surface elevation defined above. For all other materials in the coolant pool and
for all materials in all other lower cell layers, the reference elevation is the cell-bottom elevation.
It should be noted that the latter elevation is fixed and not allowed to change in conjunction with
concrete or intermediate layer inventory changes in the course of a problem.
Repository pressures are also needed to define the repository energy and inter-repository energy
transfers and are defined in the following way. For repositories adjacent to the gas space, or free
volume, in a cell, the gas pressure is taken to be the gas center-of-volume pressure, without
adjustment for the variation in gas pressure in a cell due to gas gravitational heads. Such an
assumption affects processes such as the intercell flow of liquid between pools. Note, however, that
in this case, the pressure is adjusted for the liquid heads present. The neglect of gas pressure ~
variation within a cell should affect only slightly the partitioning of liquid between pools in different
cells, or the partitioning of energy between the atmosphere and pool.
The initial energy EO,iis the total energy for repository i at the start of the calculation
(A-3)
where N~~~is the number of thermodynamic materials in the problem, m~x is the initial mass of
thermodynamic material kin repository i; ~ is the initial temperature of repository i; Rx is the initial
pressure of material k in repository i; g is the acceleration due to gravity; and ~,~ is the initial
repository-average reference elevation of material k in repository i. As discussed above, for liquid
water in a lower cell pool, this elevation is the pool-center elevation. All other average reference
elevations are either the gas-center-of-volume (gas-center) elevation, cell-center elevation, or cellbottom
elevation, depending on the repository.
The external source energy E~j is defined as the sum of the energies due to external source tables,
the coupling to external repositories, and heat conduction boundary conditions at external
boundaries:
R O A6 6/30/97