Document: NUREG-0800
Document ID: 3e2b0f8e-404f-49b4-8dde-3452e69e6218
Document Type: srp
Title: PROBABLE MAXIMUM FLOOD (PMF) ON STREAMS AND RIVERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070241.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.3
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Structural & Geosciences Branch (ESGB)Civil Engineering and Geosciences Branch (ECGB)1 Secondary - None I. AREAS OF REVIEW In this section of the safety analysis report (SAR), the hydrometeorological design basis is developed to determine the extent of any flood protection required for those structures, systems, and components necessary to ensure the capability to shut down the reactor and maintain it in a safe shutdown condition. The areas of review include the probable maximum precipitation (PMP) potential and precipitation losses over the applicable drainage area, the runoff response characteristics of the watershed, the accumulation of flood runoff through river channels and reservoirs, the estimate of the discharge rate trace (hydrograph) of the PMF at the plant site, the determination of PMF water level conditions at the site, and the evaluation of coincident wind-generated wave conditions that could occur with the PMF. Included is a review of the details of design bases for site drainage (which is summarized in SAR Section 2.4.2); a review of the runoff for site drainage and drainage areas adjacent to the plant site, including the roofs of safety-related structures, resulting from potential PMP; and a review of the potential effects from erosion and sedimentation. The analyses involve modeling of physical rainfall and runoff processes to estimate the upper level of possible flood conditions adjacent to and on site. Regulatory Guide 1.59 describes two positions with respect to flood protection for which a PMF 2 estimate is required to determine the controlling design basis conditions. If Position 1 is chosen, DRAFT Rev. 4 - April 1996 2.4.3-2 all safety-related systems, structures, and components must be capable of withstanding the effects from the controlling flood design basis. Position 2 limits the review to specific safety-related structures, systems, and components necessary for cold shutdown and maintenance thereof.