Document: NUREG-0800
Document ID: 5292500f-1078-455c-aa35-aea15092636c
Document Type: srp
Title: ENGINEERED SAFETY FEATURES SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16020A082.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.3
CFR Part: 
CFR Title: 

Content:
th - 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 7.3-9 Revision 6 – August 2016 may be automatically or manually activated, consistent with the response time requirements of the function. For digital computer-based ESFAS systems, the applicant or licensee should have performed a defense-in-depth and diversity analysis. Additionally, for advanced reactor design under 10 CFR Part 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants,” the design should provide for manual, system-level actuation of critical safety functions. SRP BTP 7-19 provides guidance for the review of diversity and defense-in- depth. G. System testing and inoperable surveillance - See SRP Appendix SRP 7.1-B, Subsections 4.9 and 4.10 or SRP Appendix 7.1-C, Subsections 5.7, 5.8, and 6.5. H. Use of digital systems - See SRP Appendix 7.0-A and SRP Appendix 7.1-D I. Setpoint determination - See RG 1.105, “Setpoints for Safety-Related Instrumentation,” and SRP BTP 7-12, BTP 7-3, Appendix 7.1-B, Subsection 4.18, and Appendix 7.1-C, Subsection 6.8. J. 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. 2. For review of a DC application, the reviewer should follow the above procedures to verify that the design, including requirements and