Document: NUREG-0800
Document ID: 6209b3e7-917d-48d2-a299-4d1230aa5b51
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550070.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
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Content:
al-time performance. Digital system architecture affects performance because communication between components of the system takes time, and allocation of functions to various system components affects timing. The architecture may also affect timing because an arrangement of otherwise simple components may have unexpected interactions. Requirements for redundancy and diversity BTP 7-21-6 Revision 5 - March 2007 may complicate timing analysis because they result in additional components and interconnections. General guidance on evaluating a system architecture is given in SRP BTP 7-14. Specific timing requirements may affect system architecture because it may not be possible to get sufficient computational performance for a specific function or group of functions from a single processor, or the locations where functions are performed may be widely separated. Timing requirements may also increase complexity, either by fragmenting the system into multiple processors or by code tuning, which makes the software product harder to understand, verify, or maintain. The digital instrumentation loop often includes the sensor, transmitter, analog-to-digital converter, multiplexer, data communication equipment, demultiplexer, computers, memory devices, controls, and displays. Timing analysis should consider the entire loop. 2. Information to be Reviewed Information to be reviewed is contained in the safety analysis report (SAR), revisions to the SAR, license amendment requests, topical reports, and other applicant/licensee documentation. The SAR and referenced documents typically contain the architectural description, design basis events and analyses, and certain design commitments. Inspections, tests, analyses and acceptance criteria (ITAAC) or detailed design documents describe designs, tests, analyses, or other methods of demonstrating satisfaction of design commitments for applications made under 10 CFR 52, "Early Site Permits; Standard Design Certifications; and Combined