Detailed Requirements for Flood Hazard Assessment

DOE-STD-1023-95

3.3 Detailed Requirements for Flood Hazard Assessment

3.3.1 General

Design and evaluation criteria for DOE facilities against flood hazards are provided by DOE-STD-

1020-2002. In accordance with DOE-STD-1020-2002, a Design Basis Flood (DBFL) shall be

established in order to carry out the design/evaluation process. The DBFL is a flood level

determined from the mean flood hazard curve and the hazard annual probability of exceedance

specified in DOE-STD-1020-2002. A probabilistic flood hazard assessment is required to develop

the flood hazard curve at the site.

In accordance with Section 3.c, for sites containing facilities with SSCs in PC 3 or 4, a site-specific

probabilistic flood hazard assessment is required. A site-specific probabilistic flood hazard

assessment at a site shall involve the following two steps:

Step 1:

Perform a flood screening analysis to evaluate the magnitude of flood hazards that may

impact the SSCs under consideration. Specific criteria for a flood screening analysis are

provided in Section 3.3.2 of this Standard.

Step 2:

Perform a comprehensive flood hazard assessment, if needed, based on the results of the

flood screening evaluation. Specific criteria for a comprehensive flood hazard assessment

are provided in Section 3.3.3 of this Standard.

In accordance with Section 3.a, for sites containing facilities with SSCs in only PC 1 and 2 and

having no existing site-specific probabilistic flood hazard assessment, it is sufficient to utilize flood

insurance studies or equivalent to estimate the DBFL.

However, for sites containing facilities with SSCs in PC 2, a reduced-scope flood hazard assessment

is generally required because most flood insurance studies available have not been conducted at a

level which is compatible with the hazard annual probability of exceedance (5 X 10-4) associated with

PC 2 SSCs. A reduced-scope site-specific probabilistic flood assessment need contain only a flood

screening analysis as specified in Section 3.3.2.

For sites which have site-specific flood hazard assessments, the SSCs in PCs 1 and 2 shall be

evaluated or designed for the greater of the site-specific values, flood insurance studies, or equivalent

unless lower site-specific values can be justified and are approved by DOE.

The flood hazard assessment shall consider all the phenomena that can cause flooding (e.g., river

flooding, storm surge, dam failure). The identification of potential sources of flooding is addressed

in Section A3.3.2.1. In addition, all sites must design a site drainage system to handle the runoff due

If a site-specific flood hazard assessment is conducted, all effects of flooding, including

submergence, waves and runups, debris, and hydrodynamic effects (e.g., peak flow velocity), shall be

considered for each identified source of potential flooding.