Flood Design Strategies

DOE-STD-1020-2002

drains and snow and ice loads. These were either developed during the

design of existing facilities or will be those from applicable regulations. If

the design criteria for the roof is exceeded (i.e., deflection, stress

allowables), the design must be revised (see Step 9).

If the DBFL for a SSC due to local precipitation produces levels of

flooding such that the performance goals (i.e., damage level due to

inundation or exceedance of design criteria allowables), are not satisfied,

design modifications must be developed. The design modifications must

provide additional capacity (i.e., runoff capacity, additional strength) to

satisfy the performance goals. Alternative design strategies are discussed

in Section 4.1.3.

10.

For SSCs that are impacted by the DBFL, emergency operation plans must

be developed to provide for the safety of personnel and to secure critical

areas to satisfy performance goals.

In principle, each SSC is designed in accordance with the requirements for the applicable

Performance Category. However, because floods have a common-cause impact on SSCs that are

in proximity to one another, the design basis for the most critical SSC may govern the design for

other SSCs or for the entire site. Stated differently, it may be more realistic economically and

functionally to develop a design strategy that satisfies the performance goals of the most critical

SSC and simultaneously that of other SSCs. For example, it may be feasible to harden a site

(e.g., construct a levee system), thus protecting all SSCs. Conversely, it may be impractical to

develop a design strategy that protects the entire site when SSC locations vary substantially (i.e.,

they are at significantly different elevations or there are large spatial separations).

The possible structural or functional interaction between SSCs should be considered as

part of the evaluation process. For example, if an SSC in Performance Category 4 requires

emergency electric power in order to satisfy the performance goals, structures that house

emergency generators and fuel should be designed to the DBFL for the Performance Category 4

SSC. In general, a systematic review of a site for possible structural or functional dependencies

is required. As an aid to the review, the analyst can develop a logic model that displays the

functional/structural dependencies between SSCs.

4.1.3 Flood Design Strategies

The basic design strategy for SSCs in Performance Categories 2 to 4 (excluding local

precipitation), is to construct the SSC above the DBFL. When this can be done, flood hazards

are not considered in the design basis except that possible raised ground water level must be

considered. The flood criteria have been established with this basic strategy in mind. Note that

local precipitation is an exception since all sites must consider this hazard in the design of the

site stormwater management system, roof systems, etc.

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