Document: NUREG-0800
Document ID: a2598df1-7ec6-43a6-9d2a-d8210d1f944f
Document Type: srp
Title: through 7.9. Additional information relevant to the review process can be found in the references in
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500461.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.1
CFR Part: 
CFR Title: 

Content:
appropriate attention should be given to requirements when addressing topics 4 through 7. The adequacy of system functional requirements is the subject of topic 4. In reviewing these requirements for conformance to ANSI/IEEE Standard 279 (Appendix 7.1-B) or to IEEE Standard 603 (Appendix 7.1-C), achievement of the design basis characteristics discussed in the appendices (7.1-B, Section 3 and 7.1-C, Section 4) is an important element in preventing errors in requirements specification. With respect to topics 5, 6, and 7, the planning and implementation activities should exhibit appropriate emphasis on the allocation of system functional requirements to components, the capture of functional and related software requirements, and the verification and control of those system and software requirements. The software requirements specification should exhibit the functional and process characteristics described in Section 3.3.a of BTP HICB-14. Formal or semi-formal methods are available for use in preparing some design outputs. Formal specification languages and high-level design languages (e.g., function block diagrams, logic diagrams, and ladder logic diagrams) are examples of such methods which can be useful for specifying certain aspects of software requirements. For example, function block diagrams are usually sufficient to specify the logical functions to be performed by a protection system. Rev. 4 — June 1997 SRP 7.0-A-8 The use of such languages reduces ambiguity and can make incomplete and inconsistent requirements easier to recognize. Furthermore, analytical tools are often available to support evaluation of ambiguity, completeness, consistency, and correctness. While the use of such languages may help to accurately specify certain aspects of requirements or design, existing languages do not support complete specification of requirements or design. For example, many formal design methods do not address timing or robustness requirements. Therefore where such