Document: NUREG-0800
Document ID: 4f141c71-35ca-4353-9047-a13efe6d56b7
Document Type: srp
Title: Revision 6 - August 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1601/ML16019A308.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
e thread audit, for each requirement traced, the reviewer should check that each requirement is complete, that the requirements are consistent with the overall safety system requirements, and that the requirement is not in conflict with some other requirement. The requirements should be understandable and unambiguous. Each requirement should be traceable to one or more safety system requirements, and the requirements traceability matrix should show where in the software the required action is being performed. The requirements traceability matrix should also show where the particular requirement is being tested. B.3.3.2 Design Activities - Software Architecture Description (SAD) NUREG/CR-6101, Section 3.3.1, “Hardware and Software Architecture,” and Section 4.3.1, “Hardware/Software Architecture Specifications,” contain relevant guidance. A SAD should be produced. The SAD should include all of the functional and software development process characteristics listed below. B.3.3.2.1 Functional Characteristics of SAD For each of the functional characteristics, the requirements imposed on the software for that characteristic should be satisfied by the software architecture. A review of the software architecture requires a concurrent review of the hardware architecture. Functional characteristics addressed by the SAD should include reliability, safety, security, and timing. Reliability means that the combined hardware and software architecture are such that individual software element failure will not compromise safety. The software architecture should identify actions to be taken in the event of error detection. The hardware and software architecture should be reviewed to verify that the propagation of errors is controlled via a well- structured modular design. Safety means that the software architecture introduces no new hazards into the safety system. The safety functions should be separated from normal operating and overhead functions, with well-defined and