Document: NUREG-0800
Document ID: 2cd63ebf-9196-42c0-880d-a80500b202a4
Document Type: srp
Title: - 15.1.4
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550005.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.1.1
CFR Part: 
CFR Title: 

Content:
evaluates the reactor protection system that operates to shut down the reactor automatically to terminate the events (anticipated operational occurrences) analyzed in this SRP section. The events are terminated by the reactor protection system in a timely manner such that fuel 15.1.1-15.1.4-7 Revision 2 - March 2007 cladding integrity is maintained. For a BWR, this means that the minimum value of the critical power ratio reached during the transient should be such that 99.9% of the fuel rods in the core would not be expected to experience boiling transition during core-wide transients. This limiting value of the minimum critical power ratio (MCPR) is called a safety limit. For example, the ABWR certified design MCPR is 1.07. For a PWR, this means that the minimum value of the departure from nucleate boiling ratio (DNBR) reached during the transient must remain above the 95/95 DNBR limit for the applicable DNBR correlation. For example, the System 80+ certified design, the DNBR is 1.24. Meeting the requirements of GDC 20 provides assurance that specified acceptable fuel design limits are not exceeded by ensuring that the reactor protection system acts in a timely manner to terminate reactor operation prior to reaching a safety limit. 5. Compliance with GDC 26 requires that one of the reactivity control systems be control rods capable of reliably controlling reactivity changes to ensure that under conditions of normal operation, including anticipated operational occurrences, and with appropriate margin for malfunctions such as stuck rods, specified acceptable fuel design limits are not exceeded. GDC 26 is applicable to this section because the reviewer evaluates these overcooling events analyzed in this section that may involve the movement of control rods in response to the initiating event, and rod misalignment, including stuck rods, can produce more severe thermal-hydraulic conditions than would otherwise exist. GDC 26 requires that the thermal margin be