ML21231A167
| ML21231A167 | |
| Person / Time | |
|---|---|
| Issue date: | 08/18/2021 |
| From: | Mike Franovich Office of Nuclear Reactor Regulation |
| To: | |
| S Mehta | |
| References | |
| Download: ML21231A167 (21) | |
Text
Risk Management Committee Meeting PWROG Meeting: August 18, 2021 Michael X. Franovich, Director Division of Risk Assessment Office of Nuclear Reactor Regulation 1
AGENDA RIPE - Updates on Temporary Staff Guidance Treatment of FLEX in PRAs and LARs Potential Endorsement of IEEE 1819-2016 Updates to RG 1.201 2
RIPE Leverages Previous Risk-Informed Initiatives Integrated Decision-making Panel (IDP) Reviews Key IDP Engineering Principles RIPE (using existing regulations)
Demonstrated Probabilistic Risk Assessment PRA Acceptability 3
Expansion of RIPE
- RIPE was originally only available to licensees who had a previously approved TSTF-505 license amendment.
- RIPE was expanded in Revision 1 to allow licensees to demonstrate they have a technically acceptable PRA using an approved TSTF-425 amendment.
- Expansion of RIPE was documented in a memo to the NRR Office Director dated June 30, 2021 (ML21180A012).
- Enclosure 1 - Guidelines for Characterizing the Safety Impact of Issues, Revision 1 (ML21180A014)
- Enclosure 2 - Temporary Staff Guidance TSG-DORL-2021-01, Revision 1 (ML21180A013) 4
Expanding RIPE TSTF-505 & Streamlined Review -
50.69 IDP or Equivalent No review of PRA or deterministic review TSTF-425 &
Risk-informed review 50.69 IDP or Equivalent Future work - Other risk information 5
Whats Next for RIPE?
Continue outreach to other interested Continue working parties and the on graded public.
Finalized Expansion approach to of RIPE to include support other levels licensees with an of risk-informed approved TSTF-425 integrated decision-license amendment making.
(ADAMS Package ML21180A011) 6
Treatment of FLEX Credit in Risk-Informed LARs
- Initially, LARs provided limited information to support credit
- Staff has been issuing multi-part RAIs to address all contingencies including human error probabilities, failure rate/demand probability, PRA upgrade, impact on application
- May 30, 2017 NRC memo
- Variety of meetings with industry 7
Guidance on Key Assumptions and Sources of Uncertainty RG RG NUREG comparison of NRC reviewer Guidance on 1.174 the PRA results with 1.200
[will] focus their 1855 Treatment of the acceptance review on key Uncertainties guidelines must be assumptions and Associated with based on an areas identified PRAs understanding of by peer reviewer the PRA as being of contributors to the PRA resultsand concern [i.e.,
the impacts of the F&Os]
uncertainties, both those that are explicitly accounted for in the results and those that are not.
8
Overarching statement on FLEX credit Permanently Human installed actions Revised equipment NEI Guidance Data sources Portable and updates equipment 9
Observations/Next Steps
- Recent adherence to NEI FLEX guidance has been mixed
- PWROG report on equipment reliability
- Revision to May 30, 2017 memo 10
Potential Endorsement of IEEE 1819-2016 "IEEE Standard for Risk-Informed Categorization and Treatment of Electrical and Electronic Equipment at Nuclear Power Generating Stations and Other Nuclear Facilities" 2004: IEEE develops October 15, 2019:
a goal to 2016: IEEE Develops IEEE requests priority December 26, 2019:
incorporate risk- IEEE 1819-for endorsement of NRC states that staff informed methods 2016 standard for IEEE 1819-2016 will consider into IEEE standards risk categorization of based on increased feasibility of for electrical and EESCs as a NRC emphasis on endorsing IEEE 1819-electronic systems complement to risk-informed 2016.
and components existing standards.
categorization.
(EESCs).
11
Potential Endorsement of IEEE 1819-2016 10 CFR 50.69 Where would IEEE 1819-2016 fit into the Reg Guide existing 1.201 regulatory framework?
NEI 00-04 -or-Other methods 12
Similar Risk Categories to RG 1.201 and NEI 00-04 Deterministic RG 1.201 and NEI 00-04 IEEE 1819-2016 13
Similar Inputs to NEI 00-04 Risk Characteriz-ation Periodic Reviews Deterministic Principles RISC EESC -
1234 specific guidance IDP Treatments Risk Insights and from Corrective Approved Actions, PRA Based on Risk Category Quantitative Method for some EESCs Sensitivity (Annex B)
Studies 14
Potential Endorsement of IEEE 1819-2016 New EESC- Quantitative specific Method for Applies to system functions not guidance Identify and develop system some EESCs associated with supplying functions based on providing power to SSCs; (e.g., fault power to the served loads (Annex B) protection, alarms, lighting), or to unanalyzed system functions For each system function, Maintain specific associations determine an overall risk by between EESCs and their power assigning numeric answers to sources essential risk questions One suggested method using a Considerations for specific sliding scale of 1-4 is provided components such as breakers, in Annex B; other methods may cables, or relays be developed 15
Endorsement Paths Endorse in full RG 1.201 Clarifications update Endorse in Part Sections not ENDORSED endorsed Endorse in full NOT New RG Clarifications ENDORSED Endorse in part Sections not endorsed 16
Potential Updates to RG 1.201 Mature Robust 50.69 Categorization Methodology Developed Over Many Years 2002 November July 2005 May 2006 South Texas 2004 NEI 00-04 50.69 Project Proof of Promulgate 10 CFR SSC Regulatory Guide 1.201 Concept 50.69 Rule Categorization Rev 1, For Trial Use Guideline August 2021 December 2017 24 sites approved 2014 Second LAR 5 LARs under review Vogtle Pilot submittal approved LARs based on RG 1.201 with changes 17
50.69 Categorization Process Evolved Beyond Current RG 1.201 Rev 1 Other Internal Fire Seismic Passive Shutdown External Events Hazards Seismic Margin PRA ANO-2 Analysis SSEL Shutdown Safety Hazard Plan Screening Fire Induced PRA Vulnerability PRA N-660 Evaluation (FIVE)
Appendix R Safe Limerick PRA PRA Shutdown Alternate Tiered Proposed Equipment List EPRI Approach (SSEL) Alternate In RG 1.201 Not yet In RG 1.201 Under AND used in RG NOT used in Review in LARs 1.201 LARs 18
Alternative Tiered EPRI Seismic Approach
- A three-tiered for plants with low, medium and high seismic hazard/margin (EPRI Report 3002012988) proposed for plants without SPRA or SMA
- To support the approach, EPRI Report uses four seismic PRAs to identify insights related to seismic risk
- Claims that most seismic risk significant SSCs are already captured by the internal events and/or fire PRAs
- Identifies unique seismic insights and failure modes
- Tier 1 (low risk) approved for several plants
- Tier 2 (medium risk) approved for one plant
- No plants have submitted for Tier 3 19 19
Limerick Application under Review
- Changes proposed to the 50.69 categorization process
- Alternate defense-in-depth methodology as described in PWROG-2015-NP, Rev. 1 (ML21082A522) in lieu of the defense-in-depth methodology in Chapter 6 of NEI 00-04
- Alternate passive pressure boundary component categorization as described in EPRI 3002015999 (ML21082A171) in lieu of the approved ANO-2 methodology
- Early stages of review 20
Questions?
21