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:
sign, 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 formal or high-level languages are used, care must be taken to ensure that requirements are not overlooked simply because they cannot be described by the specification or design language selected. All requirements must be identified and addressed. Requirements or designs may be described by any combination of languages, including any effective combination of formal languages, high- level languages, and natural languages, provided the interfaces between requirements expressed in different forms are appropriately addressed. Many formal methods deal only with a single life cycle activity. Often the outputs of one activity must be manually transformed to provide inputs for methods or tools used in subsequent activities. Where such combinations of formal methods are used, the review should confirm that the transformations are appropriately verified. Note that in some methods a single high-level description may be part of more than one design output. For example, in some programmable logic controller (PLC) implementations a single ladder logic description may describe logic requirements in the SRS, describe logic design in the SDD, and serve the function of source code. Such uses are acceptable provided that the BTP HICB-14 criteria for each design output are met. The review process described above is applicable to any digital I&C system. However, the complexity and depth of the review can vary substantially depending upon the extent, complexity, and safety significance of the systems involved. Each of these review topics is described in more detail below. C.3. Discussion of Digital System Review Topics This section provides detailed information on each of the digital system review topics identified above; information on the review of the acceptance of commercial-grade