Document: NUREG-0800
Document ID: f1629507-6318-4e71-94a6-9d6664ba96a3
Document Type: srp
Title: of the plant safety analysis report (SAR).  Although NRC did not endorse the annexes of
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070660327.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.6
CFR Part: 
CFR Title: 

Content:
ection 4 of SRP Appendix 7.1-C provides review guidance. 5. SAFETY SYSTEM CRITERIA (IEEE Std 7-4.3.2-2003 Clause 5) Clause 5 of IEEE Std 603-1991 requires that safety systems shall, with precision and reliability, maintain plant parameters within acceptable limits established for each design basis event. The following subsections address the criteria in the order they are listed in IEEE Std 7-4.3.2-2003. For some criteria there are no additional criteria beyond what is stated in IEEE Std 603-1991 and the appropriate subsection of SRP Appendix 7.1-C is referenced. 5.1. Single-Failure Criterion (IEEE Std 7-4.3.2-2003 Clause 5.1) The requirements are in IEEE Std 603-1991. Subsection 5.1 of SRP Appendix 7.1-C provides additional guidance. Clause 5.1 in IEEE Std 603-1991 defines the single- failure criterion. Guidance for the application of this criterion is provided in IEEE Std 379-2000, “IEEE Standard Application of the Single-Failure Criterion to Nuclear Power Generating Station Safety Systems,” which is endorsed by Regulatory Guide 1.53, Revision 2, “Application of the Single-Failure Criterion to Safety.” The approach stated in Clause 5.5 of IEEE Std 379-2000 is also appropriate for potential Appendix 7.1-D-4 March 2007 common-cause failures associated with computer hardware and software that have been developed under the criteria of IEEE Std 603-1991 and IEEE STD 7-4.3.2-2003. SRP Appendix 7.1-C discusses certain concerns of digital computer-based systems; for example, a design using shared databases and process equipment has the potential to propagate a common-cause failure of redundant equipment and software programming errors can defeat the redundancy achieved by the hardware architectural structure. Because of these concerns, the NRC staff has placed significant emphasis on defense-in-depth against common-cause failures within and between functions. SRP BTP 7-19 provides guidance for evaluating diversity and defense-in-depth features. SRP BTP 7-19 has