Document: NUREG-0800
Document ID: 96afb1d6-6ce9-41e4-b4ec-1fc7747bc0b2
Document Type: srp
Title: Revision 8 – January 2021
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2033/ML20339A647.pdf
Revision Date: 2023-05
Chapter: 7
Section ID: 7
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be needed. For example, an ATWS system may be credited as the diverse means of tripping the reactor, provided it is not vulnerable to the same CCF that could disable the safety function. If a diverse means is part of a safety-related system, it is then subject to the divisional independence requirements in IEEE Std 603-1991, Clause 5.6.1, which is incorporated by reference into 10 CFR 50.55a, “Codes and standards.” If the diverse means is NSR, then the requirements in IEEE Std 603-1991, Clause 5.6.3, for separation and independence between safety-related systems and NSR systems apply. 8 While required for implementing 10 CFR 50.69, the quality assurance measures called for by 10 CFR 50.69(d) are not required for the equipment comprising the diverse means, but they can serve as guidance for assessing the quality of that equipment. BTP 7-19-12 Revision 8 – January 2021 Point 4 directs the inclusion of a set of displays and manual controls in the main control room (MCR) that is independent of and diverse from the “safety computer system” discussed in points 1 and 3.9 The reviewer should determine whether this set of displays and manual controls provides for divisional independence as applicable to the specific design implementation. Depending on the design, these displays and controls should provide manual system- or division-level actuation and control of equipment to manage the “critical safety functions” (see Section B.1.2).10 Furthermore, if not vulnerable to the same CCF as the proposed safety-related DI&C system, some of the displays and manual controls from point 4 may be credited as all or part of the diverse means provided to address point 3. The point 4 phrase “safety computer system identified in items 1 and 3” refers to a safety-related DI&C system that is credited for mitigating an AOO or PA in the accident analysis. Typically, the automatic safety-related I&C system is credited, but for some events, manual safety-related controls are