ML23088A075
| ML23088A075 | |
| Person / Time | |
|---|---|
| Issue date: | 03/30/2023 |
| From: | Lundy Pressley NRC/NRR/DRA/APOB |
| To: | |
| References | |
| Download: ML23088A075 (1) | |
Text
PRA Configuration Control Workshop Tabletop Review x March 30, 2023 Lundy Pressley Reliability and Risk Analyst Office of Nuclear Reactor Regulation Division of Risk Assessment PRA Oversight Branch
Purpose of PRA Configuration Control (PCC) Initiative
- Gain familiarization with licensees PCC programs.
- Leverage insights from the information gathered from the voluntarily tabletops to develop options and a draft recommendation for the PCC framework.
- Perform PCC oversight gap analysis.
- Utilize a Balanced approach to ensure appropriate implementation of PCC programs for licensee PRA models that support risk-informed decision-making.
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Why is PCC Important?
- PRA is used to allow licensees to make important plant decisions often without NRC approval such as SSC categorization and treatment (50.69),
fire program changes (NFPA 805), Surveillance Frequency Control Program (SFCP) and Risk Informed Completion Times (RICT).
- If the PRA is not maintained up to date, plant baseline risk changes may not be properly understood, risk insights and key sources of uncertainty could be impacted but not understood, leading to quantitative estimates that underestimate risk.
- If the baseline risk model is no longer reflective of the as-built, as-operated plant, then any risk estimates and risk-informed decisions could be impacted and could impact safety management of the facility.
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PCC Requirements:
- 50.69: Specific requirement to review plant changes and OpE and Update the PRA as appropriate.
- Risk Informed Completion Time (RICT): Tech Spec - Administrative requirement that the PRA reflect the as-built, as-operated plant.
- NFPA 805: Requirement that PSA/PRA data reflect as-built, as-operated and maintained plant, and reflect OpE at the plant.
- Surveillance Frequency Control Program (SFCP): Tech Spec - Admin control of frequency changes IAW NEI 04-10. NEI 04-10 refers to RG 1.200 for Technical Adequacy for PRA which includes PRA Configuration Control.
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PRA Configuration Control Oversight Gap PRA found acceptable Issuance of SE/LA PRA Acceptable Changes/Modifications/Data/OpE T=0 T=Now Assessing the Gap Plant Modifications Operating Experience and Data No Current permanent PRA Maintenance and Upgrades NRC Oversight of PRA Changes 5
Cross-Agency Effort Working Group (WG) consists of:
- Region I
- NRR/DRA
- Region II
- NRR/DRO
- Region III
- Region IV 6
Overall Tabletops Plan Conducted 2 Public Selected Completed Developed Issue Public Meeting 8 Sites for Tabletops at Near-term Report on Workshops Tabletops all 8 Sites Recommendations Tabletops Feb & May 2022 Dec 2022 Feb 2022 April/May 2023 Apr 2022 Conduct Public Finalized Briefed Meeting/
Information Began NRC Mgt Workshop with Request for Tabletops on Tabletop Tabletop Tabletops July 2022 Observations Sites/Industry April 2022 Feb/Mar 2022 Stakeholders Mar 2023 7
Performed 8 Tabletop Site Visits, Combination of Risk-informed Initiatives
- 2 Sites with:
- 2 Sites with:
Surveillance Frequency Control Program 50.69 Risk-Informed (SFCP) Categorization of SSC National Fire Protection Association SFCP (NFPA) 805 NFPA 805
- 2 Sites with:
- 2 Sites with:
Risk-Informed Completion Times (RICT) SFCP SFCP RICT NFPA 805 50.69 NFPA 805 Performed 2 in each Region 8
Tabletop Staffing
- Team Composition (Typically 4 - 5 personnel) 2 - Reliability & Risk Analysts 1 - Headquarters Senior Reactor Analyst (SRA) 1 - Regional SRA 1 - Additional Technical Specialist (i.e., NFPA 805, as needed)
- Typically 3 days onsite 2 - 4 weeks preparation/coordination for tabletop site visit 9
Key Messages from Tabletops
- Variations on how licensees implement and manage PCC.
- NRC staff confirmed licensees are meeting the consensus standard; however, NRC staff identified several specific and general observations associated with PCC.
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Tabletop Observation 1:
Plant Representation Discrepancy The reliability of components that protect from a major flood were potentially not appropriately reflected in the internal flooding hazard group model, following a plant modification.
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Tabletop Observation 2:
Data Updates Unreliability and Unavailability Data had potentially not been updated for the internal hazard group model since 2016 (plant specific data) and 2010 (generic data).
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Tabletop Observation 3:
Operating Experience The internal events hazard model did not represent the as-built as operated-plant with regards to Open Phase Condition (OPC) as a potential pre-initiator for a scram or Loss of Offsite Power (LOOP) event.
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Tabletop General Observations
- Rigor of documentation and management of plant changes and the associated impacts on the PRA.
- Some PCC programs knowledge based versus proceduralized.
- Rigor of documentation of model changes/updates and conclusions and justification for determinations (i.e., Maintenance vs. Upgrade).
- Variations in the use of Human Reliability Analysis.
- Engineering Changes and Operating Experience (OE) inputs did not take advantage of official structured processes to alert the PRA organization for reviews.
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Tabletops Informed Future Guidance Development
- Items of Interest that were touched upon:
Licensee PRA maintenance/upgrade drivers and decision points, methods of documentation and tracking.
Potential future sample selection and areas of focus and hazard groups, risk significance, etc.
Information on potential future NRC inspection level of effort.
Potential NRC required proficiency and technical knowledge, training and qualifications for inspection staff.
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Proposed Path Forward Working Group recommendations will be covered in Part 2 of the NRC presentation, PCC Path Forward later in the Workshop.
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Questions 17