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:
for cold shutdown and maintenance thereof. The design requirements for flood protection are the subject of Regulatory Guide 1.102, "Flood Protection for Nuclear Power Plants." The material previously contained in Appendix A, "Probable Maximum and Seismically Induced Floods on Streams," has been replaced by American National Standards Institute (ANSI) Standard N170 1976, "Standards for Determining Design Basis Flooding at Power Reactor Sites,", which has been endorsed as acceptable by the NRC staff with the ex ception noted in Appendix A. In addition to informa tion on stream flooding, ANSI N170-1976 contains methodology for estimating probable maximum sur 'Copies of ANSI Standard N 170-1976 may be purchased from the American Nuclear Society. 555 North Kensington Avenue. La Grange Park, IL 60525. ges and seiches at estuaries and coastal areas on oceans and large lakes. Appendix B gives timesaving alternative methods of estimating the probable max imum flood along streams, and Appendix C gives a simplified method of estimating probable maximum surges on the Atlantic and Gulf coasts. The Advisory Committee on Reactor Safeguards has been con sulted concerning this guide and has concurred in the regulatory position. B. DISCUSSION Nuclear power plants should be designed to pre vent the loss of capability for cold shutdown and maintenance thereof resulting from the most severe flood conditions that can reasonably be predicted to occur at a site as a result of severe hydro meteorological conditions, seismic activity, or both. The Corps of Engineers for many years has studied conditions and circumstances relating to floods and flood control. As a result of these studies, it has developed a definition for a Probable Maximum Flood (PMFY and attendant analytical techniques for estimating, with an acceptable degree of conser vatism, flood levels on streams resulting from hydrometeorological conditions. For estimating seismically induced flood levels, an acceptable degree of