A Graded Approach to Software Quality Assurance
DOE Guide 414.1-4 provides a graded implementation strategy for the 10 software quality work activities. The graded approach identifies activities and sub-activities that can be implemented at varying levels of rigor based upon the potential impact on safety and the type of software type. Three grading levels are specified—Levels A, B, and C.
Level A
Includes safety software applications that meet one or more of the following criteria:
- Software failure that could compromise a limiting condition for operation.
- Software failure that could cause a reduction in the safety margin for a safety structure, system, or component (SSC) that is cited in DOE approved documented safety analysis.
- Software failure that could cause a reduction in the safety margin for other systems such as toxic or chemical protection systems that are cited in either: 1) DOE approved documented safety analysis or, 2) an approved hazard analysis per DOE P 450.1 Safety Management System Policy and the DEAR ISMS clause.
- Software failure that could result in non-conservative safety analysis, design or misclassification of facilities or SSCs.
Level B
Includes safety software applications that do not meet Level A criteria but meet one or more of the following criteria:
- Software safety management databases used to aid in decision making whose failure could impact safety SSC operation.
- Software failure that could result in incorrect analysis, design, monitoring, alarming, or recording of hazardous exposures to workers or the public.
- Software failure that could comprise the defense in depth capability for the nuclear facility.
Level C
Includes software applications that do not meet Level B criteria but meet one or more of the following criteria:
- Software failure that could cause a potential violation of regulatory permitting requirements.
- Software failure that could affect environment, safety, health monitoring or alarming systems.
- Software failure that could affect the safe operation of an SSC.
Categories of Software
For each level of SQA there are different requirements for the 10 SQA work activities based on the category of software in question. The categories of software are:
- Custom developed software (e.g., in-house developed software)
- Configurable software
- Acquired software (e.g., off-the-shelf commercial software)
- Utility calculations software
- Commercial design and analysis software.