Document: NUREG-0800
Document ID: a4cb1b75-ec12-4a5f-9042-da6e8c17fe83
Document Type: srp
Title: and 7.7 of the safety analysis report (SAR).
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500502.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.6
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Content:
sider the overall protective functions on a system level. The RTS design should be compatible with the accident analysis. It is not sufficient to judge the adequacy of the RTS only on the basis of the design meeting the specific requirements of ANSI/IEEE Std 279 or IEEE Std 603. The RTS review should address all topics identified as applicable by Table 7-1. Appendix 7.1-A describes review methods for each topic. Major design considerations that should be emphasized in the review of the RTS are identified below. • Design basis — See Appendix 7.1-B item 1 or Appendix 7.1-C item 4. • Single-failure criterion — See Appendix 7.1-B item 3 or Appendix 7.1-C item 6. • Quality 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. • Defense-in-depth and diversity — RTS 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 RTS 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