Document: NUREG-0800
Document ID: 14c7085e-8b87-4b50-97fb-a095ea003ae8
Document Type: srp
Title: describes the general procedures to be followed in reviewing any I&C system. Procedures for
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500511.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.1
CFR Part: 
CFR Title: 

Content:
with the guidance of Generic Letter 85-06. The ATWS mitigation system should be testable at power (up to, but not necessarily including, the final actuation device). • Defense-in-depth and diversity analysis — The diverse I&C system designs should be consistent with the assumptions of the applicant/licensee's D-in-D&D analysis, if one has been performed. For example, diverse I&C system equipment should be environmentally qualified for the environments in which the D-in-D&D analysis assumes they will operate. • Use of digital systems — See Appendix 7.0-A. • Power supply availability — The reviewer should confirm with EELB that power sources will be available during and following a loss of offsite power. • Environmental qualification — The diverse I&C system equipment as installed should be qualified for the environment that could exist during the events for which the equipment is assumed to respond. • System status — Information should be available in the control room to indicate the operation of the diverse I&C systems. This review may involve the considerations included in emergency operating procedures. Rev. 4 — June 1997 SRP 7.8-6 • Potential for inadvertent actuation — The diverse I&C systems design should limit the potential for inadvertent actuation and challenges to safety systems. Diverse I&C systems should be designed to initiate after the primary protection system actuation conditions are exceeded. (The use of a primary protection signal sensor to simultaneously initiate diverse I&C functions is acceptable.) Additional major design considerations that should be emphasized in the review of ATWS mitigation systems are identified below. • Independence from the RTS — The ATWS mitigation equipment should be independent and diverse from the RTS from the sensor output to the final actuation device. See Appendix 7.1-B item 8 or Appendix 7.1-C item 24. • Manual initiation capability — The ATWS mitigation systems should include the