Document: NUREG-0800
Document ID: c41ee259-fb35-4539-bbe5-ca79a00f9f6f
Document Type: srp
Title: COOLING WATER SUPPLYLOW WATER CONSIDERATIONS1
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070258.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.11
CFR Part: 
CFR Title: 

Content:
based principally on the adequacy of the ultimate heat sink to supply cooling water for normal operations, anticipated operational occurrences, and for safe shutdown, 16 cooldown (first 30 days), and long-term cooldown (periods in excess of 30 days) during adverse natural conditions. In addition, the design basis of the intake system must be adequate to enable delivery of the necessary cooling water to the plant during adverse hydrologic conditions. Where the specific design bases preclude plant operation during severe hydrologically related events, sufficient warning time must be demonstrated so that the plant may be shut down during or in advance of adverse events without causing potential damage to safety-related facilities. In cases where sufficient warning time to permit advance shutdown is considered necessary to protect safety-related components, an item in the plant Technical Specifications will be required. SAR Section 2.4.11.1 (Low Flow in Rivers and Streams): For essential water supplies the low-flow/low-level design for the primary water supply source must be based on the probable minimum low flow and level resulting from the most severe drought that can reasonably be considered possible for the region. The low flow and level design bases for operation (if different than the design bases for essential water requirements) should be such that shutdowns caused by inadequate water supply will not cause frequent use of emergency systems. In cases where a common source of cooling water for operation and safety is provided, and where operation can affect minimum levels required for safety, the system will be acceptable if technical specifications are provided for shutdown before the ultimate heat sink can be adversely affected. SAR Section 2.4.11.2 (Low Water Resulting from Surges, Seiches, or Tsunami): If the site is 17 susceptible to such phenomena, minimum water levels resulting from setdown (sometimes called runout or rundown) from hurricane surges,