Document: NUREG-0800
Document ID: 21a25622-c805-4d35-996c-a62a763f51a4
Document Type: srp
Title: describes the general procedures to be followed in reviewing any instrumentation and control
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500503.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.1
CFR Part: 
CFR Title: 

Content:
of components and modules — See Appendix 7.1-B item 4 or Appendix 7.1-C item 8. • Independence — See Appendix 7.1-B items 7 and 8 or Appendix 7.1-C items 11 and 24. • Completion of protective action — See Appendix 7.1-B item 17 or Appendix 7.1-C item 25. • Defense-in-depth and diversity — ESFAS systems should incorporate multiple means for response to each event discussed in Chapter 15 of the SAR. At least one pair of these means for each event should have the property of signal diversity, i.e., the use of different sensed parameters to initiate protective action, in which any of the parameters may independently indicate an abnormal condition, even if the other parameters are sensed incorrectly (see NUREG/CR-6303, "Method for Performing Diversity and Defense-in-Depth Analyses of Reactor Protection Systems"). The diverse means may actuate the same protective function or different protective functions, and may be automatically or manually activated, consistent with the response time requirements of the function. For digital computer-based ESFAS systems the applicant/licensee should have performed a defense-in-depth and diversity analysis. Additionally, for advanced reactor design under 10 CFR 52, the design should provide for manual, system-level actuation of critical safety functions. BTP HICB-19 provides guidance for the review of defense-in-depth and diversity. • System testing and inoperable surveillance — See Appendix 7.1-B items 10 and 11 or Appendix 7.1-C item 12, 13, and 27. • Use of digital systems — See Appendix 7.0-A. • Setpoint determination — See Draft Reg. Guide DG-1045 (the proposed revision 3 to Reg. Guide 1.105, "Instrument Setpoints for Safety Systems"), and BTP HICB-12. • ESF control systems — Conformance to the single-failure criterion on a system basis, and operability from onsite and offsite electrical power as required by GDC 34, 35, 38, and 41. In each safety review, the Staff should determine the elements of the