Document: NRC Regulatory Guide
Document ID: c7b1689b-ff17-4083-9fb1-f91b6965ea1a
Document Type: regulatory_guide
Title: Design Basis Floods for Nuclear Power Plants + HISTORY - HISTORY 02/2022 – DG-1290 , Proposed Revision 3 09/2014 – Periodic Review of Revision 2 – Revise 07/1980 – Errata to Revision 2 07/2024 – DG-1290 Revision 1 (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740388.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.59
CFR Part: 
CFR Title: 

Content:
ave activity constitute the design basis flood conditions that safety-related structures, systems, and components identified in Regulatory Guide 1.29 (see footnote 3) must be designed to withstand and retain capability for cold shutdown and maintenance thereof. a. The PMF on streams, as defined in Appendix A and based on the analytical techniques summarized in Appendices A and B of this guide, provides an ac ceptable level of conservatism for estimating flood levels caused by severe hydrometeorological con ditions. b. Along lakeshores, coastlines, and estuaries, estimates of flood levels resulting from severe surges, seiches, and wave action caused by hydrometeorological activity should be based on criteria comparable in conservatism to those used for Probable Maximum Floods. Criteria and analytical techniques providing this level of conservatism for the analysis of these events are summarized in Ap pendix A of this guide. Appendix C of this guide pre sents an acceptable method for estimating the still water level of the Probable Maximum Surge from hurricanes at open-coast sites on the Atlantic Ocean and Gulf of Mexico. c. Flood conditions that could be caused by dam failures from earthquakes should also be considered in establishing the design basis flood. Analytical techniques for evaluating the hydrologic effects of seismically induced dam failures discussed herein are presented in Appendix A of this guide. Techniques for evaluating the effects of tsunami will be presented in a future appendix. d. Where upstream dams or other features that provide flood protection are present, in addition to the analyses of the most severe floods that may be in duced by either hydrometeorological or seismic mechanisms, reasonable combinations of less-severe flood conditions and seismic events should also be 6Probable Maximum Gradient Wind is defined as a gradient wind of a designated duration, which there is virtually no risk of ex ceeding. considered to the extent needed for a