Document: NUREG-0800
Document ID: be033a97-be2a-4a23-91fe-52b123162b3b
Document Type: srp
Title: LOW WATER CONSIDERATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070730439.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.11
CFR Part: 
CFR Title: 

Content:
ct forces on the safety-related structures, this should be coordinated with the organization responsible for review of the structural design bases. For multiple purpose (normal operations, anticipated operational occurrences, and emergency shutdown and cooldown) water supply systems, the primary portion of the system should be reviewed first to determine that the water supply will be maintained at minimum volume requirements at all times. The secondary portion of the system should then be reviewed to determine whether an adequate emergency water supply can be expected to be available during operating conditions such as the regional drought of record (flows should be adjusted for historical and potential future effects). If not available, the applicant should be asked to provide a technical specification requiring plant shutdown at the point that an adequate shutdown water supply is still ensured. The ability of the ultimate heat sink to provide a 30-day supply of cooling water, as specified in Regulatory Guide 1.27, should be independently evaluated. For those cases where makeup water cannot be ensured (e.g., an onsite cooling pond supplied from a nearby river through nonseismic piping), estimates of water loss due to drift, evaporation, blowdown, and seepage should be made. Techniques described in NUREG-0693 and NUREG-0733 should be used to evaluate the adequacy of the initial water inventory under meteorological conditions of the severity discussed in Regulatory Guide 1.27. If the ultimate heat sink system is not capable of continued long-term water supply under the criteria in Regulatory Guide 1.27 or the above considerations, the system should be reviewed in two parts: short-term capability and long-term capability. For short-term capability, the organization responsible for the review of cooling water systems and the Licensing Project Manager (LPM) should be informed if the independently estimated supply appears to be less than 30 days. The applicant should be