Document: NUREG-0800
Document ID: ebff6c02-bdd3-4751-9e36-9347caf05c8e
Document Type: srp
Title: and 2.4.6 are applicable to low water estimates due to the various phenomena discussed.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070258.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.5
CFR Part: 
CFR Title: 

Content:
of plant structures, systems, and components important to safety. Meeting the requirements of Appendix A to 10 CFR Part 100 provides assurance that plant structures, systems, and components important to safety are designed to withstand appropriately severe hydrologic phenomena and be capable of performing their intended safety functions.25 III. REVIEW PROCEDURES Minimum plant requirements (water level and flow) that are identified in SAR subsection 2.4.11.5 or 9.2.5 are compared towith the estimated minimum water levels and flows given in section subsection 2.4.11.1. If normal operation is not assuredensured at the 26 27 minimum water supply conditions, and loss of normal operation capability can adversely affect safety-related components, estimates of warning time are reviewed to assureensure that 28 shutdown or conversion to alternate water sources can be accomplished prior to the trip. For such cases, emergency operating procedures are required, and are reviewed to assureensure that 29 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)SPLB. Determination of the dependability of the 30 ultimate heat sink is accomplished by using Regulatory Guide 1.27 as a standard of comparison. Each source of water for normal operations, anticipated operational occurrences, or emergency 31 shutdown and cooldown, and the natural phenomena and site-related accident design criteria for each should be identified. First, a systems analysis is first undertaken of all water supply sources to determine the 32 likelihood that at least one source would survive: 1. The most severe of each of the natural phenomena, 2. Site-related accident phenomena, and DRAFT Rev. 3 - April 1996 2.4.11-8 3. Reasonable combinations of less severe natural and accident phenomena. Second, arbitrarily assumed mechanistic failures of water