Document: NUREG-0800
Document ID: 106978f1-fb10-4fa9-ad95-601f3c16bd36
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550072.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
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Content:
perators with the information needed to place and maintain the plant in a hot shutdown condition. Human factors engineering 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. 4. Review Procedures The applicant/licensee's D3 analysis is reviewed against the above acceptance criteria using the detailed guidance of NUREG/CR-6303. Emphasis should be given to the following topics: 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 errors, will not propagate to other equipment or software. BTP 7-19-8 Revision 5 - March 2007 Examples of typical blocks are computers, local area networks, and programmable logic controllers. 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/licensee. Postulated Common-Cause Failures In certain cases, the Staff has concluded that software-based components are sufficiently simple and deterministic in performance that measures such as, for example, online error checking and exhaustive testing provide adequate assurance that the component is not a significant source of common-cause failure. Common-cause failure of such components need not be considered in the course of a D3 analysis. When a basis is given that a block is not susceptible to software common-cause failure, the Staff should examine