Document: NUREG-0800
Document ID: f689fb6d-4711-4972-b900-1b2001877b19
Document Type: srp
Title: TSUNAMI HAZARDS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1819/ML18190A200.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.6
CFR Part: 
CFR Title: 

Content:
vious decade. Changes were made to update the text with editorial and clarifying statements, including utilizing consistent terminology within this SRP section and planned updates within the other SRP 2.4 sections. A key change to this SRP section was to delete the word “probable” from both the SRP section title and elsewhere in the body of the text. This particular word implies a probabilistic aspect to an analysis that is still essentially deterministic. Similarly, the terms “maximum” and “probable maximum” have been deleted. It is the staff’s view that these terms equate to the term “consequential flood” (discussed below) that is the focus of the review outlined in this SRP section. As there might be multiple flooding maxima at multiple locations within the powerblock due to tsunamis (as well as other flood-causing mechanisms), the staff’s regulatory interest is in that water surface elevation that would be instrumental in defining the design basis for the purposes of the regulations; thus, the staff’s preference for the use of the term “consequential flood(ing).” As noted above, a new term “consequential flooding” has been defined and introduced. In reference to any consequential flooding, the staff is now proposing that licensees prepare inundation maps identifying the elevation of flood waters in relation to the SSCs within the reactor powerblock. Depending on the reactor sites’ topography and geography, the powerblock and service water and ultimate heat sink intake structures may be at different elevations relative to each other. As a consequence, the staff is also proposing that applicants calculate separate flooding levels corresponding to these two features’ locations as the tsunami’s wave amplitude may vary across the reactor site owing variable site topography and the presence of multiple as-built reactor structures. The staff envisions that the requisite calculations would be represented by one of more inundation maps