Document: NUREG-0800
Document ID: b3542dd9-b995-4eba-aa6c-0f8f08f8c772
Document Type: srp
Title: FLOODS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340525.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.2
CFR Part: 
CFR Title: 

Content:
events in the region. SRP Sections 2.4.3 through 2.4.7 discuss methods of analysis to determine the individual flood-producing phenomena. III. REVIEW PROCEDURES Construction permit (CP) stage reviews are carried out under this SRP section to evaluate the significance of the controlling flood level with regard to the plant design basis for flood protection. At the operating license (OL) stage, a brief review is carried out to determine if new information has become available since the CP review and to evaluate the significance of the new information with regard to the plant design basis for flood protection. New information might arise, for instance, from the occurrence of a new maximum flood of record in the site region, from identification of a source of major flooding not previously considered,' from construction of new dams, from flood plain encroachments, or from advances in predictive models and analytical techniques. If the CP-stage evaluation of flooding potential has been carefully done, all sources of major flooding should have been considered and any new floods of record should fall well within the design basis. Improvements in calculational methods may occur, but generally will be concerned with increased accu- racy in stream flow and water level predictions rather than with substan- tive changes in the flows and levels predicted. Where the OL review reveals that the controlling flood level differs more than 5% less conser- vatively from the CP evaluation, any supplemental provisions needed in the flood protection design basis should be directed toward early warning measures and procedures for ensuring safe shutdown of the plant or toward minor structural modification to accommodate the design flood level. For SAR Section 2.4.2.1 (Flood History): The staff will review publications of the U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), Soil Conservation Service (SCS), Corps of Engineers, applicable State and river