Document: NUREG-0800
Document ID: 74415b71-98a0-4109-9ba7-8a72a89a3d18
Document Type: srp
Title: ULTIMATE HEAT SINK
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070520.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.2.5
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Auxiliary Systems Branch (ASB)Plant Systems Branch (SPLB)1 Secondary - None I. AREAS OF REVIEW The ultimate heat sink (UHS) is the source of cooling water provided to dissipate reactor decay heat and essential cooling system heat loads after a normal reactor shutdown or a shutdown following an accident, including a loss-of-coolant accident (LOCA). The design of the UHS 2 must satisfy the requirements of General Design Criteria 2, 5, 44, 45, and 46. The ASBSPLB reviews the water sources which make up the ultimate heat sink. This includes 3 the size, type of cooling water supply (e.g., ocean, lake, natural or manmade reservoir, river, or cooling tower), makeup sources to the ultimate heat sink, and the capability of the heat sink to deliver the required flow of cooling water at appropriate temperatures for normal, accident, or shutdown condition of the reactor. The UHS is reviewed to determine that design code requirements, as applicable to the assigned quality classifications and seismic categories, are met. A related area of review is the conveying system, which is generally the service water pumping system. The service water system is reviewed under Standard Review Plan (SRP) Section 9.2.1. 4 1. The ultimate heat sink is reviewed with respect to the following considerations: a. The type of cooling water supply. b. The ability to dissipate the total essential station heat load. DRAFT Rev. 3 - April 1996 9.2.5-2 c. The effect of environmental conditions on the capability of the UHS to furnish the required quantities of cooling water, at appropriate temperatures and with any required chemical and purification treatment, for extended times after shutdown. d. The effect of earthquakes, tornadoes, missiles, floods and hurricane winds on the availability of the source water. The UHS is also reviewed to assure ensure that 5 adverse environmental conditions including freezing will not preclude the safety function of the UHS. e. Sharing of