Code Manual for CONTAIN 2.0 - Federation of American Scientists

included in vtiPti The definition of vP~is discussed in Section 4.4.8. Other contributions to % from
engineered systems operation are discussed in Sections 7.4 through 7.6.
In CONTAIN, the user should note that aerosols wilI not deposit onto the submerged portion of an
inner surface of a heat transfer structure or on an outer surface if the outer face of the structure is not
specified to be in the cell in which the structure is defined, even if aerosols are present in the cell in
which the outer face resides. The outer surface of a ceiling structure is considered a floor deposition
area and the outer surface of a floor structure is considered a ceiling deposition area. If surfaces
with deposited aerosols and fission products are subsequently submerged, the deposited aerosols and
fission products are transferred to the pool in proportion to the previously unsubmerged area that is
subsequently submerged.
The user should also note that a lower cell coolant pool must be defined for deposition onto the
lower cell, discussed in Chapter 5, to occur. The reason for this restriction is that the aerosol
deposition arrays are associated with the lower cell coolant pool and not the lower cell system. If
a pool is present, the deposition will occur on a pool area equal to the cell cross-sectional area at the
pool height, as defined in Sections 4.1 and 14.3.1.1. If such a pool is logically defined but has zero
mass, deposition will occur on the pool substrate. This substrate may consist either of lower cell
layers or the basemat, with an area equal to the lower cell substrate area, or of the CORCON upper
melt surface, if CORCON is active. The user should also note that if a pool is defined, the SETTLE
keyword is no longer necessary to enable such deposition. The lower cell substrate area does not
. have to correspond to the entire bottom cross-sectional area of the cell, since the cell bottom may
be partially or completely spanned by a floor heat transfer structure or by a flow path opening. In
the latter case, aerosols may be transported through gas flow paths by settling if the VCOSN
keyword is used in the ENGVENT input block to define a flow path inclination angle. (See Sections
7.8 and 14.2.4.2.)
7.3 Aero sol Sources
Aerosol sources, which contribute to the ~ term in Equation (7-3), may consist of two types, internal
and external. As discussed in Chapter 5, aerosols maybe produced internally through the effects of
CCI, as modeled within the CORCON Mod3 module. The size distribution of such aerosols are
calculated within the VANESA routines within CORCON. Sources may also be explicitly specified
by the user. Such user-supplied sources may be introduced directly into the atmosphere or in
conjunction with gas sources under the surface of the coolant pool through the safety relief valve
(SRV) model. When introduced through the SRV model, the aerosols will be scrubbed as described
in Section 7.7 before being added to the atmosphere.
The size distribution of aerosols initially present or introduced into a cell from an external source
is assumed to be lognormal as described in Section 7.1. The distribution is normally given by the
constant “amean” and “avar” parameters specified in the global AEROSOL block (see Section
14.2.5). These parameters correspond to the spherical-equivalent mass median diameter and the
natural logarithm of the geometric standard deviation with respect to diameter, respectively. Each
aerosol component or species may have a different distribution. However, by using the AERTIM
option, also described in Section 14.2.5, or the SRV model, discussed in Sections 11.2 and 14.3.4,
Rev. O 7-23 6/30/97