Document: NUREG-0800
Document ID: efac696f-0049-4b65-b562-4a813c1d817c
Document Type: srp
Title: STANDBY LIQUID CONTROL SYSTEM (BWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070538.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.3.5
CFR Part: 
CFR Title: 

Content:
neutron absorber in solution, along with the capability DRAFT Rev. 3 - April 1996 9.3.5-6 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to bring the reactor from rated power to cold shutdown (at any time in core life with the control rods remaining withdrawn in the rated power pattern, taking into account the reactivity gains from complete decay of the rated power xenon inventory, an allowance for imperfect mixing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 26.31 3. 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 for fine and coarse control of reactivity in a BWR are the control rods and their drive system, with the SLCS serving as a backup system. As such, the SLCS is a reliable and automatic means of making the reactor subcritical following an anticipated transient with a failure of the shutdown rods to insert. Acting in conjunction with other features to mitigate an ATWS, the SLCS provides additional protection and safety for all barriers to the release of fission products by reducing the potential for exceeding fuel, reactor coolant pressure boundary and containment integrity limits.32 4. Compliance with 10 CFR 50.62(c)(4) invokes explicit requirements regarding the performance of the SLCS. 10 CFR 50.62(c)(4) states, in essence, that each boiling water reactor must have a SLCS with a minimum flow capacity and boron content providing equivalent reactivity control to 326 Lpm (86 gpm) of 13 weight percent sodium pentaborate solution. As discussed in Generic Letter 85-03 (Reference 7), the "equivalent in control capacity" wording was chosen to allow flexibility in the implementation of the requirement (e.g., the equivalence can be obtained by