Code Manual for CONTAIN 2.0 - Federation of American Scientists

The cell geometries assumed in CONTAIN 1.2 are based on a representation of the cell in which
up to 10 different constant cross-sectional areas maybe specified through the CELLHIST keyword ~
as a function of height, relative to a common reference for the entire problem. The cell geometry
is assumed freed in time. The cross-sectional areas represent the area associated with the principal
atmosphere and pool fluids. Heat transfer structures, the coolant film on structures, and any lower
cell layers except for the coolant pool are assumed to have been excluded from the specified cell
cross sections. One possible cell configuration is shown schematically in Figure 4-2 for the case of
three different cross sections.
For old files lacking an explicit specification of cross-sectional areas through the new CELLHIST
input, a single cross-sectional area is assumed and taken to be “volume’’/’’height,” where the gas
“volume” and “height” are parameters previously required in the cell GEOMETRY block The
obsolete keyword ELEVCL in the FLOWS input is also used to define the initial gas center of
elevation. The pool volume, if any, is added to the “volume” parameter to obtain the total cell
volume. A diagnostic is given whenever the lower cell area is significantly different from the new
cell cross-sectional area(s), as major changes in pool-atmosphere heat transfer areas and pool depths
may occur. The user should also be aware that extremely large values of “height,” for example, for
cells representing the environment, may produce spurious effects because of the unrealistically large
gravitational heads involved.
4.2 Flow Path ConfiswrationS
The recommended procedure with respect to flow paths is to construct them, in general, from
engineered vents, which are specified through the ENGVENT input blockl discussed in Section
14.2.4.2. These flow paths have unlimited connectivity, in the sense that any number maybe used
to connect a given pair of cells. Beginning with CONTAIN 1.2, a given flow path modeled within
this option may now transport either the atmosphere fields or the pool fields. The atmosphere and
pool fields may flow only in a path of the appropriate type, defined by the user to be either GAS or
POOL, respectively. Thus, it is necessary to deftne both a GAS and a POOL path in the ENGVENT
block to represent any physical path in which both fields can flow, and it is assumed that the user
will do this if necessary. The flow of the atmosphere and pool fields within their respective paths
is taken to be independent, in the sense that the effects of interracial shear and void fraction effects
are neglected within the flow paths. However, gas-pool equilibration and liquid head effects related
to the coverage of the inlet or outlet of a gas path by pool coolant are taken into account. In addition,
a simple pool-gas hierarchy determines when gas or pool coolant can flow in a GAS or POOL path.
For example, gas is not allowed to flow in a GAS path when the inlet is submerged to any
appreciable degree below the surface.
CONTAIN flow paths are considered to be attached to a cell at a point, rather than a range of
elevations corresponding to the physical opening height. By default, as shown in Figure 4-3, a gas
path is attached at the tops of the cells connected by the path, and a pool path is attached to the
bottoms of the cells. The user may speci~ the elevations at which each of the flow path ends are
lThe option to use “regular” flow paths within the FLOWS input block is considered obsolete. However, if used,
these paths are treated as type GAS. The input format for such flow paths is discussed in Appendix B.
Rev O 44 6/30/97