Document: NUREG-0800
Document ID: 861c72fa-b163-4443-a01e-48d1504c12a6
Document Type: srp
Title: INTERLOCK SYSTEMS IMPORTANT TO SAFETY
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159B156.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.6
CFR Part: 
CFR Title: 

Content:
and IEEE Std 603-1991, respectively, and how they are used in the review of the interlock systems. SRP Appendix 7.1-D discusses the criteria of IEEE Std 7-4.3.2 and how they are used in the review of interlocks. Although the primary emphasis is on the equipment comprising the interlock systems, the reviewer should consider the interlock functions at the system level. The interlock systems design should be compatible with the SAR Chapter 15 design bases accident analyses. It is not sufficient to evaluate the adequacy of the interlock systems only on the basis of the design’s meeting the specific requirements of IEEE Std 279-1971 or IEEE Std 603-1991. The interlock systems review should address the applicable topics identified in SRP Table 7-1. SRP Appendix 7.1-A describes review methods for each topic. Major design considerations that should be emphasized in the review of the interlock systems are identified below. A. Single-failure criterion - See SRP Appendix 7.1-B, Subsection 4.2 or SRP Appendix 7.1-C, Subsection 5.1. B. Quality of components and modules - See SRP Appendix 7.1-B, Subsection 4.3 or SRP Appendix 7.1-C, Subsection 5.3. 7.6-6 Draft Revision 6 – August 2015 C. Independence - See SRP Appendix 7.1-B subsections 4.6 and 4.7 or SRP Appendix 7.1-C, Subsections 5.6 and 6.3. D. System testing and inoperable surveillance - See SRP Appendix 7.1-B, Subsections 4.9, 4.10, and 4.13 or SRP Appendix 7.1-C, Subsections 5.7, 5.8, and 6.5. E. Use of digital systems - See SRP Appendix 7.0-A and SRP Appendix 7.1-D. F. Interlocks to prevent over-pressurization of low-pressure systems - See SRP BTP 7-1. G. Interlocks to prevent over-pressurization of the primary coolant system during low-temperature operations of the reactor vessel - See SRP BTP 5-2. H. Interlocks for ECCS accumulator valves - See SRP BTP 7-2. I. Interlocks required to isolate safety systems from nonsafety systems. J. Interlocks required to preclude inadvertent inter-ties between redundant or diverse