Document: NUREG-0800
Document ID: eea126bc-3192-4a98-b937-2f09794010cd
Document Type: srp
Title: COOLING WATER SUPPLY
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340556.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.11
CFR Part: 
CFR Title: 

Content:
to the trip. For such cases, emergency operating pro- cedures are required, and are reviewed to assure that they are consistent with the postulated conditions. The-analysis'of the dependability of the ultimate heat sink is reviewed and the conclusions are provided to the Auxiliary Systems Branch (ASB) and Power Systems Branch (PSB). Determination of the dependability of the ultimate heat sink is accomplished by using Regulatory Guide 1.27 as a standard of comparison. Each source of water for normal or emergency shutdown and cooldown, and the natural phenomena and site-related accident design criteria for each should be identified. A systems analysis is first undertaken of all water supply sources to determine the likelihood that at least one source would survive (1) the most severe of each of the natural phenomena; (2) site-related accident phenomena; and (3) reasonable combinations of less severe natural and accident phenomena. Second, arbitrarily assumed mechanistic failures of water supply structures and conveyance systems are postulated and the systems analysis repeated, to assure that the failure of one component will not cause failure of the entire system. These analyses are coordinated with the ASB and PSB review of the ultimate heat sink and related cooling systems, to avoid duplication. Operating rules for each portion of the system are ascertained to determine the amount of water that can be assumed available in the event of normal or accidental shutdown. If there is evidence of potential structural or mechanical effects, the Structural Engineering Branch (SEB) or Mechanical Engineering Branch (MEB) will be requested by HGEB to ascertain whether the effects are properly con- sidered in the structural or mechanical design bases for the plant. Consulta- tions with the Geosciences-Branch (GB), the Accident Evaluation Branch (AEB), SEB, ASB, and PSB are undertaken where design criteria are not firmly established. The potential for surges in intake sumps (i.e.,