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:
ifications are provided for shutdown before the ultimate heat sink can be adversely affected. The staff will evaluate the applicant’s evidence as it relates to low water considerations. If the staff disagrees with the applicant’s conclusions, they will request additional information. The applicant should fully document and justify its estimates or accept the staff’s estimates and redesign the SSC important to safety affected by low water levels. 2.4.11-8 Revision 3 - March 2007 The staff should use the suggested criteria of Regulatory Guide 1.27 when the water supply comprises part of the ultimate heat sink. For plants using rivers, minimum design service water levels are compared with asymptotic extrapolations of low-flow frequency curves which have been corrected for historical and potential future effects. Conservative estimates of low flow using statistical methodologies as used by the USGS provide magnitudes of low flow of specified recurrence interval and need to be used as indicators of low streamflow under hydrological drought conditions. For coastal or estuary plants, design low water levels are compared with probable maximum hurricane and tsunami-induced low water levels. For Great Lakes plants, design low water levels are compared with minimum historical levels coincident with probable maximum surge or seiche-induced low water levels. If historical flows and levels are used to estimate design values by inference from frequency distribution plots, the data used should be presented so that the staff can make an independent determination. The data and methods of NOAA, USGS, the Natural Resources Conservation Service, the Bureau of Reclamation, and the Corps of Engineers are used by the staff in its independent review. 2. Low Water from Other Phenomena: The effects to low water from other phenomena (including potential blockage of intakes by sediment, debris, littoral drift, and ice) are reviewed along with a complete history of low water conditions in