ML20038A314
| ML20038A314 | |
| Person / Time | |
|---|---|
| Issue date: | 02/07/2020 |
| From: | Tekia Govan NRC/NRR/DRO/IRSB |
| To: | |
| Govan T, NRR/DRO, 415-6197 | |
| References | |
| Download: ML20038A314 (11) | |
Text
Draft Branch Technical Position 7-19, Revision 8 Public Meeting NRC Staff Presentation February 11, 2020
Agenda
- Background on Commissions Common Cause Failure (CCF) Policy
- Key Proposed Changes:
Incorporates the guiding principles from SECY 18-0090 Categorization Scheme and Graded Approach Qualitative Assessment Means to Eliminate CCF from Further Consideration Spurious Operation Assessment Re-structuring of Branch Technical Position (BTP) 2
- SRM-SECY-93-087 presents the Commissions four-point policy on how potential CCFs should be addressed in DI&C systems
- SECY-18-0090 clarifies the application of the Commissions direction in the four positions within SRM-SECY-93-087 Recognizes significant effort has been applied to the development of highly reliable DI&C systems but residual faults within digital systems may lead to CCFs Provides five guiding principles for updating the staffs guidance for addressing CCF Guiding principles were incorporated into draft BTP 7-19, Revision 8 3
Proposed Categorization Scheme and Graded Approach 4
Safety-Related NSR Safety Significant Significant contributor to plant safety A1 Perform D3 Assessment B1 Perform Qualitative Assessment Not Safety Significant Not a significant contributor to plant safety A2 Perform Qualitative Assessment B2
Proposed Qualitative Assessment Framework
- Based upon Supplement 1 to RIS 2002-22, now utilized as part of the graded approach to address CCF
- Evaluate potential CCFs and their effects in A2 and B1 systems (i.e. sufficiently low likelihood of failure)
- For B2 systems, basis for not performing an assessment should be documented 5
Proposed Guidance for Means to Eliminate CCF from Further Consideration 6
- Diversity - Clarifies guidance for application within the DI&C system or component
- Testing - Clarifies criteria and terminology associated with use of testing to eliminate CCF from further consideration
- Defensive Measures -
Use defensive measures to prevent, limit, or mitigate the effects of a potential CCF to eliminate CCF from further consideration Provides criteria for use of other methodologies with the provision of a technical basis and acceptance criteria Based on NRC-approved methodology
Proposed Spurious Operation Guidance Enhancement
- Provides bifurcated criteria for addressing spurious operation:
- Operating reactors: existing safety analysis not invalidated by the proposed digital modification
- Enhanced guidance for new and advanced reactors
- Clarifies scope and methods for performing the assessment 7
Proposed Re-Structuring of BTP 7-19
- Simplifies background and incorporates new guidance on CCF
- Maps criteria to four positions in the SRM-SECY-93-087
- Consolidates CCF guidance and corresponding acceptance criteria 8
Next Steps
- Public comment period ends March 16, 2020
- ACRS Sub-Committee scheduled for June 25, 2020
- ACRS Full Committee meeting in July 2020
- Final issuance targeted for September 2020 9
10 Questions
11 Acronyms BTP Branch Technical Position NSR Not safety related CCF Common Cause Failure PRA Probabilistic Risk Assessment CFR Code of Federal Regulations RIS Regulatory Issue Summary D3 Defense-in-Depth and Diversity RPS Reactor Protection System DI&C Digital Instrumentation and Control SAR Safety Analysis Report ESFAS Engineered Safety Feature Actuation System SRM Staff Requirements Memorandum MCR Main Control Room SSC Structure, System and component MP Modernization Project