Code Manual for CONTAIN 2.0 - Federation of American Scientists

7.5 ~ Ice
The ice condenser provides conditions under which significant deposition of suspended aerosols
fromthe atmosphere canoccur. The&rosol deposition model fortheice condenser tieats setding,
impaction/interception, Brownian diffusion, diffusiophoresis, and thermophoresis. The model is
based on the ICEDF model of Winegardner, Postma, and Jankowski, [Win83] with minor
modifications to make it consistent with other CONTAIN models. (Also see Reference 0wc85b.)
In contrast to the aerosol dynamic modeling presented in Section 7.2, the ice condenser thermalhydraulic
and aerosol deposition models use boundary layer values of physical quantities where
appropriate and also treat noncondensable gas media other than air, using the approximations
discussed in Sections 10.1 and 10.2.
The deposition modeling discussed below includes only effects attributable to the ice and ice basket
structures. Note that aerosol decontamination is calculated even in the absence of ice, because the
large surface areas represented by the ice baskets could be effective in removing particulate. The
walls, floors, and ceiling of the ice compartment should be modeled separately as heat transfer
structures. The deposition modeling for such structures is discussed in Section 7.2.3.
The aerosols and associated fission products that are removed from the atmosphere through ice and
ice basket interactions are placed in the pool, if present, in the cell “iclout” specified by the user for
the ice condenser. This treatment assumes that there is no holdup of aerosols and fission products
in the ice compartment. One consequence is that fission product decay heating does not contribute
to the melting of the ice. The “iclout” destination is also that used for the melt/condensate resulting
from ice condenser operation. If a pool is not present in the designated cell, the aerosols and fission
products will be placed in the waste repository of the designated cell.
The ice and ice basket contribution to the aerosol fractional removal rate 3 (s-l) from the five
mechanisms described above may be expressed as
(7-23)
where the terms on the right represent the effects of gravitational settling, Brownian diffusion,
thermophoresis, diffusiophoresis, and interceptionlimpaction, in that order. Turbulent deposition
is not modeled because it can be shown to have a negligible effect. ~in83]
- Theremov~ rate
velocity and the surface area
const~t
for savi~tion~ se~ing % is simPIYthe Product of the settling
(7-24)
where v, is defined as in Equation (7-17), except that actual ice boundary layer values are used for
gas properties, and A, is defined as
Rev. O 7-25 6/30/97