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:
nd accuracy design specifications. Robustness requires that the system be coded in such a way that corrupted data will not cause the safety system to fail. Data corruption should be avoided. All input data should be checked to ensure that the correct data is being read and that the data is in the correct format. All messages should be checked to ensure that the correct message is being read and that the message contents are in the correct format. Appropriate corrective actions should take place if any of these criteria are violated. Safety requires that the code introduce no new hazards into the safety system. Security requires that the code introduce no new security threats into the safety system software. Timing requires that the execution time be deterministic. BTP HICB-21 provides additional guidance on real-time performance. Software Development Process Characteristics Appendix 7-A Rev. 4 — June 1997 BTP HICB-14-35 Software development process characteristics exhibited by the code documents should include completeness, consistency, correctness, style, traceability, and verifiability. Completeness requires that the code meet all the specifications of the design and all implementation constraints. The software implementation should be compatible with the hardware environment. Consistency requires that all variable names, types, locations, and array sizes be defined consistently throughout the software units. The code should use mathematical equations which correspond to the mathematical models, algorithms, and numerical techniques described in or derived from the SDS. All parameters passed between software units should be consistent with respect to number, type, structure, physical units, and direction. Minimum and maximum execution times should be consistent with expected overall performance. Correctness requires that the code be correctly implemented. Style requires that the programming style constraints specified in the design documents be followed.