Code Manual for CONTAIN 2.0 - Federation of American Scientists

Heat transfer between layers can be set to zero through the use of the table option, but there is a
simpler method. This involves the use of the keyword HT-TRAN, followed by five flags. The
HT-TRAN option can be used to completely turn off all heat transfer between layers, between the
basemat and the bottommost layer, and between the uppermost lower cell layer and the upper cell.
Note that the heat transfer from the CORCON layer cannot be turned off if CORCON is active. The
HT-TRAN option is discussed in more detail in Sections 10.7 and 14.3.1.6.
5.5.3 Lower Cell Conduction Modeling
If CORCON is not active, a simple one-dimensional heat conduction model is used to calculate heat
transfer between the various layers in the lower cell, from the uppermost layer downward. The lower
cell conduction algorithm is identical to that used for structures as described in Section 10.5.3 and
the reader is referred to that section for details. However, only slab geometry is allowed. The crosssectional
area used for the conduction solution is that given by the lower cell GEOMETRY keyword
discussed in Section 14.3.2.1. In applying this model to the lower cell, the basemat below the first
layer is handled as a surface temperature boundary condition. This temperature is specified
following the BC keyword in the lower cell input block. The interlayer heat transfer coefficients
used in the lower cell conduction model are described in Sections 5.5.1 and 5.5.2. The interlayer
heat transfer coefilcients are by default internally calculated as discussed in Section 5.5.1, but may
be overridden by the user through the HT-COEF option (as discussed in Section 5.5.2).
If CORCON is specified but is not active initially, the conduction model is operative prior to the
start time for the CORCON calculations and after CORCON finishes, but not while CORCON is
active. Moreover, the conduction model assumes that core debris is absent prior to the CORCON
start time and is present after CORCON finishes. This approach is used to allow the starting
temperature of the debris in the cavity to be specified by the user (see TOXIDE and TMETAL in the
intermediate layer input) without being affected by the conduction model prior to initiation of CCI
phenomena modeling in CORCON.
5.6 LQwer Cell Mass and Enerw Addition
The sections below discuss various ways that mass and energy may be added to the lower cell layers.
These include the decay heating by explicit fission products discussed in Section 8.5; the ANSIstandard
DECAY-HT makeup decay power model discussed in Section 5.6.1 below; external
material sources to the lower cell discussed in Section 5.6.2 below; and the QVOL external
volumetric heating model discussed in Section 5.6.3 below.
The application of these models is complicated by the possible presence of null layers (containing
at most deposited aerosols and fission products) and the possible use of the CORCON model to
describe CCIS. In the case of fission product, DECAY-HT, and QVOL heating of null layers, the
heating is simply reassigned to the first node below that is not null, unless CORCON has been
invoked. If CORCON has been invoked and is active, the fission product, DECAY-HT, and QVOL
heating models are ignored for the intermediate and concrete layers representing CORCON, with the
exception that the DECAY-HT makeup power, plus any explicit fission product heating assigned
to the CORCON intermediate layer is used to scale the total decay power in the CORCON melt
layers. In the case of a null coolant pool, any heating directed to the pool layer from the above three
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