Document: NUREG-0800
Document ID: b9d43224-eb4e-4b19-a212-b3bb8c0ffbb5
Document Type: srp
Title: Diversity and
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070660258.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.9
CFR Part: 
CFR Title: 

Content:
Defense-in-Depth Review * * * Same review as supported system(s) Functional Requirements Review Review Limited review Review Same review as supported system(s) Development Process Review Review Limited review Review Same review as supported system(s) Process Implementation Review Review Limited review Review Same review as supported system(s) Design Outputs Review Review Limited review Review * While a diversity and defense-in-depth analysis is not required for systems other than RTS and ESFAS, changes to other I&C systems in plants that have existing digital RTS and ESFAS should be reviewed to confirm that the proposed changes do not affect assumptions and commitments made in the existing diversity and defense-in-depth analysis. This includes ensuring compliance with the diversity requirements of 10 CFR 50.62, as discussed in SRP Section 7.8. The level of review depends upon the importance to safety of the system under review. Control systems receive a limited review as necessary to confirm that control system failures cannot have an adverse effect on safety system functions and will not pose frequent challenges to the safety systems. An area of special emphasis for control Appendix 7.0-A-11 Revision 5 - March 2007 systems is to assure that the control system design is consistent with the commitments for control system/safety system independence. Isolation of safety systems from control system failures should be addressed. Data communication systems are treated as support systems (see SRP Section 7.9), although they are often composed of specialized hardware, embedded software, and communication protocol software that runs on the computers linked together by the data communication system. They may support protection systems, other safety systems, diverse I&C systems, control systems, or any combination thereof. A design may provide separate safety and non-safety data communication systems. The review topics applicable to any data communication system are the