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:
vity 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 safety-related functions is not compromised for each unit, regardless of equipment failures or other events that may occur in another unit. Meeting the requirements of GDC 5 provides assurance that unacceptable effects of equipment failures or other events occurring in one unit of a multiunit site will not propagate to the unaffected unit(s). 4. Compliance with GDC 26 requires that two independent reactivity control systems of different design principles be provided, with one of the systems being capable of holding the reactor core subcritical under cold conditions. In a BWR, the normal method of reactivity control utilizes control rods, which are capable of maintaining the reactor subcritical, including an allowance for a stuck rod, without the addition of any poison to the reactor coolant. The SLCS acts as an emergency backup to the insertion of control rods to provide a diverse means of making the reactor subcritical. Making provisions for the storage of an adequate amount of neutron absorber in solution, along with the capability for injection at a rate sufficient to bring the reactor from rated power to cold shutdown (at any time in core life with the control rods remaining withdrawn in the rated power pattern, taking into account the reactivity gains from complete decay of the rated power xenon inventory, an allowance for imperfect mixing and leakage, and dilution by the residual heat removal system), assures that the SLCS will the meet the performance requirements of GDC 26. 5. Compliance with GDC 27 requires that two independent reactivity control systems of different design principles be provided, with the reactivity control systems having a combined capability of reliably controlling reactivity changes under design-basis accident conditions. The primary means