Document: NUREG-0800
Document ID: 8b98402f-b225-4b85-948c-c6f2a4cb5e09
Document Type: srp
Title: POTENTIAL DAM FAILURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070242.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.4
CFR Part: 
CFR Title: 

Content:
96 The staff will review the applicant's analyses and independently assess the coincident river flows at the site and at the dams being analyzed. ANSI N170 provides guidance on acceptable river 8 flow conditions to be assumed coincident with the dam failure event. The applicant's estimates (which may include landslide-induced failures) of the flood discharge resulting from the coincident events should be no more than 5% less conservative than the staff's estimates to be acceptable. If the applicant's estimates differ by more than 5%, the applicant should fully document and justify its estimates or accept the staff's estimates and redesign applicable flood protection. For SAR Section 2.4.4.1 (Dam Failure Permutations): The location of dams and potentially "likely" or severe modes of failure must be identified. The potential for multiple, seismically induced dam failures and the domino failure of a series of dams must be discussed. Approved models of the Corps of Engineers and the Tennessee Valley Authority are used to predict the downstream water levels resulting from a dam breach (Refs. 7, 11, 16, 17 and 18 8, 12, 17, 18, and 19). First-time use of other models will require complete model description and 9 documentation. Acceptance of the model (and subsequent analyses) is based on the staff review of model theory, available verification, and application. Where other than instantaneous failure is assumed, the conservatism of the rate of failure and shape of the breach should be well documented. A determination of the peak flow rate and water level at the site for the worst possible combination of dam failures and a summary analysis (that substantiates the condition as the critical permutation) must be presented, along with a description (and the bases) of all coefficients and methods used. Also, the effects of other concurrent events on plant safety, such as blockage of the river and water-borne missiles, must be considered. For SAR Sections 2.4.4.2 (Unsteady Flow