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:
the SER input accordingly. Wind-generated wave action will be independently estimated using Corps of Engineers criteria such as the "Shore Protection Manual." When sufficient water depth is available, the significant wave height and runup are used for structural design purposes, and the 1% wave height and runup are used for flood level estimates. Where depth limits wave height, the breaking or broken wave height and runup is used for both purposes. For condition 3 (i.e., a "dry site"--one not subject to stream flooding by virtue of local topographic considerations), the following procedures apply: 1. Use Corps of Engineers PMF estimates for other sites in the region to develop "regional drainage area versus PMF discharge (cubic feet per second/square mile) (m per sec/km 3 2 (ft per sec/mi ))" data, for extrapolation to the site. 3 2 11 2. Envelop the above data points to obtain an estimate of the PMF applicable to the site. 3. Increase the estimate based on a judgment as to the applicability of the basic estimates. An increase in the range of 10% to 50% is generally appropriate. 4. If warranted by relative elevation differences between the site and adjacent stream, estimate the flood level at the site using slope-area techniques or water surface profile computations. 5. Estimate wind (2-yr extreme windspeed) wave runup based on breaking or 1% wave heights. Criteria for estimating windspeed are discussed in ANSI N170 and References 12 16, 18, and 19. 17, 19, and 20. 13 6. Compare resultant water level with proposed plant grade and lowest safety-related facility that can be affected. The above items of review are performed only when applicable to the site or site region. Some items of review may be done on a generic basis. For standard design certification reviews, site-related parameters, including probable maximum precipitation (PMP), should be identified in the site parameter envelope. The specified value should be representative of credible, bounding