Document: NUREG-0800
Document ID: 062bafc6-0bc5-4a2f-a566-7200c0c49d7a
Document Type: srp
Title: ENGINEERED SAFETY FEATURES SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159B099.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.3
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pment comprising the ESFAS, the reviewer must consider the overall ESF functions at the system level. The ESFAS design should be compatible with the accident analyses. It is not sufficient to evaluate the adequacy of the ESFAS only on the basis of the design meeting the specific requirements of IEEE Std 279-1971 or IEEE Std 603-1991. The ESFAS review should address the applicable topics identified as applicable 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 ESFAS review are identified below. 7.3-7 Draft Revision 6 – August 2015 A. Design basis - See SRP Appendix 7.1-B, Subsection 3 or SRP Appendix 7.1-C, Subsection 4. B. Single-failure criterion - See SRP Appendix 7.1-B, Subsection 4.2 or SRP Appendix 7.1-C, Subsection 5.1. C. Quality of components and modules-See SRP Appendix 7.1-B, Subsection 4.3 or SRP Appendix 7.1-C, Subsection 5.3. D. 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. E. Completion of protective action - See SRP Appendix 7.1-B, Subsection 4.16 or SRP Appendix 7.1-C, Subsection 5.2. F. Diversity and defense-in-depth - ESFAS should incorporate multiple means for responding to each event discussed in the SAR Chapter 15, “Transient and Accident Analyses.” 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