Table 4-2 Design Basis Flood Events

DOE-STD-1020-2002

Table 4-2 Design Basis Flood Events

Primary Hazard

Case No.

Event Combinations*

River Flooding

Peak flood elevation. Note: The hazard analysis for river flooding

should include all contributors to flooding, including releases from

upstream dams, ice jams, etc. Flooding associated with upstream-dam

failure is included in the dam failure category.

Wind-waves corresponding, as a minimum to the 2-year wind acting in

the most favorable direction (Ref. 4-2), coincident with the peak flood or

as determined in a probabilistic analysis that considers the joint

occurrence of river flooding and wind generated waves.

Ice forces (Refs. 4-2 and 4-3) and Case 1.

Evaluate the potential for erosion, debris, etc. due to the primary

hazard.

Dam Failure

All modes of dam failure must be considered (i.e., overtopping,

seismically induced failure, random structural failures, upstream dam

failure, etc.)

Wind-waves corresponding, as a minimum to the 2-year wind acting in

the most favorable direction (Ref. 4-2), coincident with the peak flood or

as determined in a probabilistic analysis that considers the joint

occurrence of river flooding and wind generated waves.

Evaluate the potential for erosion, debris, etc. due to the primary

hazard.

Local Precipitation

Flooding based on the site runoff analysis shall be used to evaluate the

site drainage system and flood loads on individual facilities.

Ponding on roof to a maximum depth corresponding to the level of the

secondary drainage system.

Rain and snow, as specified in applicable regulations.

Storm Surge, Seiche

Tide effects corresponding to the mean high tide above the MLW** level

(due to hurricane,

(if not included in the hazard analysis).

seiche, squall lines, etc.)

Wave action and Case 1. Wave action should include static and

dynamic effects and potential for erosion (Ref. 4-2).

Levee or Dike Failure

Should be evaluated as part of the hazard analysis if overtopping and/or

failure occurs.

Snow

Snow and drift roof loads as specified in applicable regulations.

Tsunami

Tide effects corresponding to the mean high tide above the MLW** level

(if not included in the hazard analysis).

* Events are added to the flood level produced by the primary hazard.

** MLW-Mean Low Water.

The DBFL for a SSC for a flood hazard (e.g., river flooding, local precipitation) is

defined in terms of:

Peak-hazard level (e.g., flow rate, depth of water) corresponding to the

mean, hazard annual exceedance probability (see Table 4-1), including the

4-3