Document: NUREG-0800
Document ID: c90016c6-e03f-4224-8ff3-87a6f7d3ca42
Document Type: srp
Title: Appendix 7-A
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500547.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
s additional guidance on real-time performance. Software Development Process Characteristics Software development process characteristics exhibited by the SRS should include completeness, consistency, correctness, style, traceability, unambiguity and verifiability. Completeness requires that all actions required of the computer system be fully described for all operating modes and all possible values of input variables (for example, the complete span of instrument inputs or clock/calendar time)*. The SRS should describe any actions that the software is prohibited from executing. The operational environment within which the software will operate should be described. All variables in the physical environment that the software must monitor and control shall be fully specified. Functional requirements should describe (1) how each function is initiated; (2) the input and output variables required of the function; (3) the task sequences, actions, and events required to carry out the function; and (4) the termination conditions and system status at the conclusion of the function. User interfaces should be fully described for each category of user. Consistency requires that the contents of the SRS be consistent with the safety system requirements, the safety system design, and documented descriptions and known properties of the operational environment within which the safety system software will operate. Individual requirements should not contradict other requirements. Timing requirements should be consistent with thermohydraulic analyses performed in the system safety analysis. Uniform and consistent terminology, notation, and definitions should be used throughout the SRS. Correctness requires that the description of actions required of the computer system be free from faults and that no other requirements be stated. The operational environment within which the software will operate should be accurately described. All variables in the physical environment that the software