Document: NUREG-0800
Document ID: 5e40cf60-028d-44c3-b9b8-735a6a68a48a
Document Type: srp
Title: Revision 6 - August 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16020A036.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
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aspects related to system performance and timing. NUREG/CR-6083 describes real-time systems with respect to performance, timing, and complexity. These documents include detailed guidance for reviewing such systems and a glossary of related terms. BTP 7-21-6 Revision 6 – August 2016 3. Purpose The purpose of this BTP is to provide guidance for NRC staff to verify conformance with the previously cited regulatory bases and standards in the design of digital computer systems. This BTP has three objectives: • To verify that system timing requirements calculated from the design basis events and other criteria have been allocated to the digital computer portion of the system as appropriate, and have been satisfied in the digital system design and implementation. • To make the reviewer aware that more extensive efforts are required to verify certain timing design and implementation techniques, such as interrupts. • To assess the technical basis for concluding that the installed plant systems perform as predicted when enlarged from small-scale or partial-system engineering prototypes used in the design phases. B. BRANCH TECHNICAL POSITION 1. Introduction System architecture needs to be considered in evaluating real-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 may complicate timing analysis because they result in additional components and interconnections. General guidance on evaluating a system’s 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