ML21006A006

NEI 20-07 - Overview Presentation - Jan 12, 2021, Guidance for Addressing Software CCF in High Safety Significant Safety-related Di&C Systems

ML21006A006
Person / Time
Site:	Nuclear Energy Institute
Issue date:	01/12/2021
From:	Vaughn S Nuclear Energy Institute
To:
Govan T
References
NEI-20-07
Download: ML21006A006 (12)

Text

©2021 Nuclear Energy Institute Guidance for Addressing Software CCF in High Safety Significant Safety-related DI&C Systems NEI 20-07 January 12, 2021

©2021 Nuclear Energy Institute 2 Reasons for moving on from the NEI 16-16 approach Overall concept and structure of NEI 20-07 Agenda This Photo by Unknown Author is licensed under CC BY

©2021 Nuclear Energy Institute 3 NEI 16-16:

Too much technical detail with no clear tie to regulation or standards Included hardware defensive design measures without establishing a technical basis for each NEI 20-07:

Focuses the guidance on quality software development Enables use of state-of-the art defensive design measures based on industry standards without being overly prescriptive Departure from NEI 16-16 Approach This Photo by Unknown Author is licensed under CC BY-SA

©2021 Nuclear Energy Institute 4 NEI 20-07 Approach

©2021 Nuclear Energy Institute 5 1.

Software quality depends on complete and correct requirements, design, review, implementation, and testing 2.

Concurrent triggering conditions are required to activate a latent software defect 3.

The effects of a software CCF can be reduced by design 4.

Operating history can provide evidence of software quality 1st Principles This Photo by Unknown Author is licensed under CC BY-SA

©2021 Nuclear Energy Institute 6 Each of the 1st principles has a clear connection to various NRC regulations to include:

50.55(a)(h)

Various 10 CFR Part 50, Appendix A General Design Criteria (GDC)

Various 10 CFR Part 50, Appendix B Quality Assurance Criterion 1st Principles Connect to Regulations This Photo by Unknown Author is licensed under CC BY

©2021 Nuclear Energy Institute 7 SDO Definition: Objective criteria for addressing the potential for a software defect being introduced during the software development and integration processes Approximately 70 defined SDOs that yield software quality Provided for both platform and application software Formulated using IEC 61508 and EPRI research Safe Design Objectives (SDOs)

©2021 Nuclear Energy Institute 8 Application software requirements are derived from, and backward traceable to, the functional and performance requirements of the affected plant systems and their design and licensing bases (10.1.3.1)

A hazard analysis method is used to identify hazardous control actions that can lead to an accident or loss, and application software requirements and constraints are derived from the identified hazardous control actions (10.1.3.2)

SDO Examples from NEI 20-07 This Photo by Unknown Author is licensed under CC BY-SA

©2021 Nuclear Energy Institute 9 Each SDO:

is linked to one or more 1st principle has established goals SDOs 1st Principles NRC Regulations Creates a verifiable and defensible chain SDOs Connect to 1st Principles This Photo by Unknown Author is licensed under CC BY-NC-ND

©2021 Nuclear Energy Institute 10 Document adherence with the SDOs Traceable method to clearly demonstrate how each SDO was met Justification for any exceptions taken to a given SDO Assurance Case This Photo by Unknown Author is licensed under CC BY-NC-ND

©2021 Nuclear Energy Institute 11 1st Principles completely describe the progression from systematic failures (latent software defects) to CCFs in plant systems Each 1st Principle aligns with one or more NRC regulations Meeting Safe Design Objectives (SDOs) supports and upholds the 1st Principles Various defensive design meaures can be used to meet SDOs as evidenced and documented by the Assurance Case Summary This Photo by Unknown Author is licensed under CC BY-NC-ND

©2021 Nuclear Energy Institute 12 Fall 2020 - NEI 20-07 provided to NRC Staff for pre-endorsement/informal review January 12, 2021 - Initial public meeting to kickoff the document review February/March XX, 2021 - public meeting to begin detailed discussion of NEI 20-07 Q2 and Q3 2021 - Future public meetings to discuss NEI 20-07 content Q4 2021 - NEI 20-07 submittal for NRC formal endorsement Proposed Schedule This Photo by Unknown Author is licensed under CC BY-NC