Document: NUREG-0800
Document ID: 9697248b-d015-42be-8808-2202db24977a
Document Type: srp
Title: STANDBY LIQUID CONTROL SYSTEM (BWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070680186.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.3.5
CFR Part: 
CFR Title: 

Content:
n a safe- shutdown condition, the SLCS, and structures housing the SLCS, must be capable of withstanding the effects of natural phenomena. Based on reviewing a number of safety analysis reports (SARs) for light-water reactor nuclear power plants, a seismic design classification system was developed for identifying those plant features that should be designed to withstand the effects of the SSE. Regulatory Guide 1.29, Position C-1, states that systems required for safe shutdown, including their foundations and supports, are designated as Seismic Category I and should be designed to withstand the effects of the SSE and remain functional. Compliance with Regulatory Guide 1.29 provides assurance that the SLCS will perform its intended safety function in the event of an earthquake. 2. GDC 4 requires SSCs that are important for safety to be designed to accommodate the effects of, and to be compatible with, the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents and to be appropriately protected against dynamic effects, including the effects of missiles, pipe whipping, and discharging fluids, that may result from equipment failures and from external events. The SLCS provides backup reactivity control, and the dynamic effects of water hammer could degrade system effectiveness. Compliance with GDC 4 assures that the SLCS will remain functional and provide backup reactivity control. 3. GDC 5 prohibits the sharing of SSCs among nuclear power units unless it can be shown that such sharing will not significantly impair their ability to perform their safety functions, including, in the event of an accident in one unit, an orderly shutdown and cooldown of the remaining units. In general, the SLCS provides backup reactivity control; however, in some newer designs such as the ESBWR the SLCS provides ECCS functions. The 9.3.5-6 Revision 3 - March 2007 SLCS needs to be designed such that the ability to accomplish these