Document: NUREG-0800
Document ID: dc63e8aa-2a74-4078-9e19-9a26ed1b4d8c
Document Type: srp
Title: Revision 6 – July 2012
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1105/ML110550791.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
d be independent of the safety system such that a CCF of the safety system would not affect the diverse system. Revision 6 – July 2012 BTP 7-19-8 Concerning Point 4: Point 4 directs the inclusion of a set of displays and manual controls (safety or non-safety) in the main control room (MCR) that is diverse from any CCF vulnerability identified within the “safety computer system” discussed in Points 1 and 3 above and meets divisional independence requirements as applicable for the specific design implementation. These displays and controls are for manual, system level or divisional level (depending on the design) actuation and control of equipment to manage the “(plant) critical safety functions” (see Section B.1.2 above). Further, if not subject to the CCF, some of these displays and manual controls from Point 4 may actually be credited as all or part of the diverse means called for under Point 3. The Point 4 phrase “. . . . safety computer system identified in items 1 and 3 above.” refers to the safety-related automated RTS and ESFAS. For digital system modifications to operating plants, retention of existing analog displays and controls in the MCR could satisfy this point (see Section B.1.5, "Manual Initiation of Automatically Initiated Protective Actions Subject to CCF"). However, if existing displays and controls are digital and/or the same platform is used to provide signals to the analog displays, this point may not be satisfied. Where the Point 4 displays and controls serve as the diverse means, the displays and controls also should be able to function downstream of the lowest-level components subject to the CCF that necessitated the use of the diverse means. One example would be the use of hard-wired connections. Once manual actuation from the MCR using the Point 4 displays and controls has been completed, controls outside the MCR for long-term management of these (plant) critical safety functions may be used when supported by suitable HFE