Code Manual for CONTAIN 2.0 - Federation of American Scientists

The safety assessment of these designs also presents some new challenges. In particular, the existing
USNRC-sponsored analysis tools were not originally designed to address the passive safety features ~
found in these designs. The USNRC reactor safety rese~ch program has therefore undertaken to
adapt as necessary and apply their severe accident analysis tools to the analysis of ALWR behavior
under accident conditions. The two designs that are receiving the most attention at the time of this
writing are the AP600 design by Westinghouse and the simplified boiling water reactor (SBWR)
design by General Electric. The certification of these designs and possibly others will require the
USNRC to apply these adapted tools to the performance of the reactor and containment systems
under both severe accident and design basis accident conditions. As a result, some of the new
modeling capabilities in CONTAIN, such as the film tracking model discussed in Section 10.2.2.1,
address the unique features of the ALWR designs.
The need for containment analysis is common to all US commercial LWR containment types.
Therefore, CONTAIN 2.0 is intended to be applicable to large dry pressurized water reactor (PWR)
containment, subatmospheric PWR containment, suppression pool containment of boiling water
reactors (BWRs) (including horizontal and vertical vents), ice condenser containment, and passively
cooled ALWR containment.
1.2 Difference s Between CONTAIN 2.0 and Earlier Versions
The CONTAIN 2.0 code represents the third major version of CONTAIN. The first two major
versions were released in 1984 and 1988 as CONTAIN 1.0 ~er85b] and as CONTAIN 1.1,
[Mur89a, Mur89b, Was91] respectively. Table 1-1 lists the code versions from 1.0 through 2.0 and
summarizes the major improvements, new models, and other items contained in each version.
CONTAIN 1.1 and 2.0 incorporate numerous significant improvements and advancements not
included in CONTAIN 1.0. The CONTAIN 1.1 changes are summarized in References Mur89a and
Was91. The improvements offered by CONTAIN 2.0 over CONTAIN 1.1 are equally numerous and
significant.
Many of the latter improvements are embodied in interim versions. Four such versions have been
released: CONTAIN 1.11, CONTAIN 1.12, CONTAIN 1.12V, and CONTAIN 1.2. Table 1-2 shows
the oftlcial update sets incorporated in each of these interim versions. While CONTAIN 1.11, 1.12,
1.12V, and 1.2 are in use by a number of users (as approved by the USNRC on a case-by-case basis)
this manual for CONTAIN 2.0 represents the f~st formal documentation provided since CONTAIN
1.1. Some of the models in the interim versions may have been revised or replaced; therefore,
interim documentation on these versions may not agree with the descriptions provided in this code
manual.
Table 1-3 indicates the code version(s) associated with the addition of a new modeling capability or
code feature or the revision of an existing one and also lists the sections of this report where the
reader can obtain more information about the indicated model additions or revisions. Numerous
minor, but important, fixes to modeling errors or code bugs were also implemented but are not listed
in this table.
Rev. O 1-4 6/30/97