Code Manual for CONTAIN 2.0 - Federation of American Scientists

12.0 ENGINEERED SAFETY FEATURE MODELS
The models in CONTAIN for the three major engineered safety features (ESFs)--fan coolers, ice
condensers, and containment sprays--are described in this section. Thermal-hydraulic effects and
the removal of aerosols (and associated fission products) from the atmosphere are modeled, as is the
removal of gaseous iodine species for spray systems (but not fan coolers or ice condensers). The
heat exchangers typically used in the containment spray system and various liquid transport system
components (tanks, pumps, valves, pipes, orifices, and pool overflows) associated with the ESFS are
also modeled. The liquid transport system can also function independently of the basic ESF models.
Restrictions on the allowed combinations of systems and components are discussed in the
appropriate subsections. Boiling water reactor (BWR) suppression pools, often described as an ESF,
are also modeled, but are described in Chapter 11. Key elements of the ESF models are illustrated
in Figure 12-1.
The arrangements of some of the engineered system components used with an ESF are illustrated
by the containment spray system of a light water reactor, shown in Figure 12-2. The spray can be
used to produce steam condensation, a drop in temperature, and reduction of fission product
concentrations in the atmosphere. After initiation of the spray, water from the water storage tank
(WST) flows through nozzles located near the top of the containment dome. Upon reaching the
floor, the spray water drains into the cavity sump (pool). When the water in the WST is exhausted,
recirculated water from the sump is pumped through a cooling heat exchanger and then to the spray
nozzles. The ESF framework allows a detailed description of such a system. Alternatively, the user
may simply specify the mass flow rate and temperature versus time through the spray system.
The removal of aerosols from the atmosphere through the operation of ESFSis discussed in Sections
7.4 through 7.6. Except in the case of sprays, the only fission products considered in this modeling
are those attached to aerosols. For sprays, however, the removal of molecular iodine and gaseous
organic iodides is also modeled as described in Section 8.6. The removed aerosols and fission
products are conveyed, along with the effluent from operation of the ESF, to the coolant pool, if
present, in cell “iclout,” which is specified in the ENGINEER input block (see Section 14.3.3).
Otherwise, they are placed in the waste repository of “iclout.”
The optional FPLIQUID global input block described in Section 14.2.5.1 can be specified to allow
liquid transport system components or pool flow paths to carry fission products from one pool to
another (see Section 8.8.2). Such fission product transport between pools occurs only in conjunction
with single components, such as a pipe, that are connected between pools. Such transport does not
occur, for example, when the spray system is operated in a recirculation mode between two different
pools. Only those fission products with non-zero user-specified values of “fpliq” will be transported
to the destination pool. The fraction of fission products transferred with the liquid is equal to the
fraction of liquid transferred from a pool times “fpliq.” Note that the “fpliq” values also control the
washdown of fission products from structure surfaces, as discussed in Section 8.8.2.
An engineered systems source table maybe used to provide a time-dependent source of coolant at
a specified temperature or enthalpy to an ESF. Because of the nature of the systems modeled, the
only allowed source material is water. This option otherwise is specified much like the other source
Rev O 12-1 6/30/97