Document: NUREG-0800
Document ID: 4865fc6d-b85f-4173-9bca-162fa9fe67d2
Document Type: srp
Title: Appendix 7-A
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500555.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
Systems Branch, the Mechanical Engineering Branch, and the Materials and Chemical Engineering Branch is necessary in reviewing these analyses.) Identification of Alternative Mitigation Capability For each design-basis event, alternate mitigation actuation functions are identified that will prevent or mitigate core damage and unacceptable release of radioactivity. Where a common-mode failure is compensated by a different automatic function, a basis is provided which demonstrates that the different function constitutes adequate mitigation for the conditions of the event. Where operator action is cited as the diverse means for response to an event, the applicant/licensee should demonstrate that adequate information (indication) and sufficient time is available for operator action. Justification for Not Correcting Specific Vulnerabilities If any identified vulnerabilities are not addressed by provision of alternate trip, initiation, or mitigation capability, justification should be provided. Justification may be based upon the availability of systems outside of the scope of the analysis that act to prevent or mitigate the event of concern. For example, I&C system vulnerability to common-mode failure affecting the response to large-break loss-of-coolant accidents and main steam line breaks has been accepted in the past. This acceptance was based upon the provision of primary and secondary coolant system leak detection, and pre-defined operating procedures that together enable operators to detect small leaks and take corrective actions before a large break occurs. C. References ANSI/IEEE Std 279-1971. "Criteria for Protection Systems for Nuclear Power Generating Stations." ANSI/IEEE Std 379-1988. "Standard Application of the Single-Failure Criterion to Nuclear Power Generating Station Safety Systems." IEEE Std 603-1991. "IEEE Standard Criteria for Safety Systems for Nuclear Power Generating Stations." NUREG-0493. "A Defense-in-Depth & Diversity Assessment of the