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:
or corrosion products, as recommended in Generic Letter 89-13 (Reference 12). The program for surveillance and control is reviewed by SPLB as indicated in subsection I of this SRP section.42 3. Plants utilizing cooling towers as the ultimate heat sink are reviewed as described above and in addition the reviewer determines that: a. The tower structure and basin design bases in the SAR include requirements for withstanding design basis natural phenomena or combinations of such phenomena at historically observed intensities. The natural phenomena to be considered include tornadoes, tornado missiles, hurricane winds, floods, and the SSE. b. The results of failure modes and effects analyses show that the mechanical systems (fans, pumps, and controls) can withstand a single active failure in any of these systems, including failure of any auxiliary electric power source, and not prevent delivery of water in the quantities and at temperatures required for safe shutdown. c. Adequate net positive suction head (NPSH) can be provided to all essential pumps considering variations of water level in the basins. This is verified by performing independent calculations. d. The towers can provide the design cooling water temperature under the worst combination of adverse environmental conditions including freezing, and that the 9.2.5-9 DRAFT Rev. 3 - April 1996 supply of water in the basins can provide a 30-day capability for long-term cooling at the required temperature without makeup unless acceptable makeup capabilities can be demonstrated. This is verified by independent calculations. e. Cooling towers or spray ponds used as a UHS and designed to withstand the effects of tornado missiles need not be designed to seismic Category I if another UHS is also available that is designed to meet the seismic classification guidelines of Regulatory Guide 1.27. 4. Reactor sites that utilize large natural or manmade water sources which for all practical purposes have an infinite supply of