Document: NUREG-0800
Document ID: 6cac2015-4823-4421-9a34-1ee7f23d1ec2
Document Type: srp
Title: or ESFAS — Section 7.3):
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500512.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.2
CFR Part: 
CFR Title: 

Content:
ement of IEEE Std 279 with regard to the system reliability and testability. Therefore, the Staff finds that the DCS satisfies these requirements of GDC 21. Based on the review of software development plans and the inspections of the computer development process and design outputs, the Staff concludes that the computer systems conform to the guidance of Reg. Guide 1.152. Therefore, the special characteristics of computer systems have been adequately addressed, and the Staff finds that the DCS satisfies these requirements of GDC 21. DCS functions were included in the Staff's review of defense-in-depth and diversity analysis for RTS and ESFAS. Based upon this review, the Staff concludes that the protection systems, including the DCS functions, comply with the criteria for defense against common-mode failure in digital I&C systems. Therefore, the Staff finds that adequate diversity and defense against common-mode failure has been provided to satisfy the diversity requirements of GDC 22 and the Staff Requirements Memorandum on SECY-93-087, item II.Q. The staff has reviewed EMI/RFI susceptibility and seismically exposed portions of the DCS. Based upon this review and the finding that the requirements of GDC 2 are satisfied, the staff concludes that the DCS satisfies the requirement for independence from the effects of natural phenomena. The DCS conforms to the guidelines in Reg. Guide 1.75 for protection system independence. Based on the review of system independence and separation, the Staff concludes that the DCS satisfies the requirement of IEEE Std 279 or IEEE Std 603 with regard to systems independence. Therefore, the Staff finds that the DCS satisfies the requirements of GDC 22. DCS failure modes were accounted for in the failure modes and effects analysis for the RTS and ESFAS. Based upon the Staff's review of these analyses, the Staff concludes that the protection systems, including the DCS, are designed to fail into a safe mode if a condition such as