Document: NUREG-0800
Document ID: 757b676a-0f71-4094-8677-ca3a50743281
Document Type: srp
Title: Revision 7 – August 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1601/ML16019A344.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

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equipment that performs the coordinated actuation logic. The displays may include digital components that are not adversely affected by a CCF of the safety functions credited in the accident analysis. Functional characteristics (e.g., range, accuracy, time response) should be sufficient to provide operators with the information needed to place and maintain a plant in a safe shutdown condition. HFE principles and criteria should be applied to the selection and design of the displays and controls. Human-performance requirements should be described and related to the plant safety criteria. Recognized human-factors standards and design techniques should be employed to support the described human-performance requirements. BTP 7-19-20 Revision 7 – August 2016 4. Review Procedures In reviewing the applicant’s D3 analysis using the above acceptance criteria and the detailed guidance of NUREG/CR-6303, emphasis should be given to the following topics: 4.1 System Representation as Blocks The system being assessed is represented as a block diagram; the inner workings of the blocks are not necessarily shown. Diversity is determined at the block level. A block is a physical subset of equipment and software for which it can be credibly assumed that internal failures, including the effects of software and logic errors, will not propagate to other equipment or software. Examples of typical blocks are computers, local area networks, and programmable logic controllers. 4.2 Documentation of Assumptions Assumptions made to compensate for missing information in the design description materials or to explain particular interpretations of the analysis guidelines as applied to the system are documented by the applicant. 4.3 Exclusion of Components from D3 Analysis A software-based component may be sufficiently simple and deterministic in performance such that the component is not a source of a CCF. Such components need not be considered in a D3 analysis. When a basis is given that a