ML20289A694
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| ML20289A694 | |
| Person / Time | |
|---|---|
| Issue date: | 10/08/2020 |
| From: | Michael Montecalvo NRC/NRR/DRA |
| To: | |
| Kichline M | |
| Shared Package | |
| ML20289A715 | List: |
| References | |
| Download: ML20289A694 (11) | |
Text
NRCs audit results for the PWROGs FLEX OpE data collection and analysis Mike Montecalvo, U.S. NRC NEI FLEX Summit September 2020 1
Objective
- Brief History
- Audit Team
- PWROG approach
- Audit Results
- Path Forward
- Questions 2
Project History
- One of the two remaining challenges to crediting FLEX
- Highlighted from the beginning of crediting FLEX project
- Credit for FLEX has been provided
- Data is needed to support efficient decisions
- PWROG took over the effort (2017)
- Access to the PWROG report (March 2020)
- Audit - March 24-25 extended to May 4th Commissions PRA policy statement:
PRA evaluations in support of regulatory decisions should be as realistic as practicable and appropriate supporting data should be publicly available for review.
3
Audit Team
- Team
- Matt Humberstone (NRR/DRA)
- John Lane (RES/DRA)
- Mike Montecalvo (NRR/DRA)
- Frank Arner (RI SRA)
- Zhegang Ma (INL)
- Idaho National Lab Support
- Shawn St. Germain
- John Schroeder
- Andrea Mack (Statistics)
- Cynthia Gentillon (Statistics) retired
- Cory Atwood (Statistics) retired
- Tom Wierman 4
PWROG Approach PWROG-18043-P rev.0, FLEX Equipment Data Collection and Analysis
- GOAL: Consistent with NUREG/CR-6928, Industry-Average Performance for Components and Initiating Events at U.S. Commercial Nuclear Power Plants
- Did not address CCF or unavailability
- Data Compilation
- Data from all nuclear sites
- Condition reports (CRs), preventative maintenance (PMs),
- Component Boundaries
- Common FLEX equipment (589 pieces of equipment, 16 categories)
PWROG Approach Continued PWROG-18043-P rev.0, FLEX Equipment Data Collection and Analysis
- Used INLs Nuclear Reliability and Operating Experience Database (NROD) and the RADS calculator to support their calculations
- Data Analysis Approach (3 methods)
- Empirical Bayes (EB) (8 parameters)
- Jeffreys Noninformative Prior (JNI) (13 parameters)
- Weakly Informed Prior (WIP) (11 parameters)
- Parameters with weak operating experience
- < 50 demands or <100 hrs operating
- Represents 54 out of 582 pieces of FLEX equip (~ 9% )
- Uses permanently installed equip as priors
- Engineering judgement 6
PWROG Results PWROG-18043-P rev.0, FLEX Equipment Data Collection and Analysis
- Table 6-1, Generic Failure Rates for FLEX Equipment
- Failure Mode
- Distribution
- Mean
- Method (EB, JNI, or WIP)
- Most failure probabilities are greater than similar permanently installed equipment
Audit Result/Observations
- PROCESS
- Need for explicit failure definition
- Formal update process needed
- Component Boundary definitions
- DATA COLLECTION
- Overall data pedigree (PM frequencies aligned with actual starts)
- Data collected from before FLEX was officially established
- Does run data reflect loaded conditions
- DATA ANALYSIS
- WIP method relies heavily on engineering judgement
- Potential errors in WIP results
- CCF and unavailability 8
Path Forward
- PWROG to review the NRCs audit summary
- Potential adjustments to process
- Finalize FLEX OpE data analysis report
- Publicly available
- NRC audit team plans to review PWROGs final report
- NRC will establish a position on final report
- The process/results could have significant changes 9
Conclusions
- NRC Audit Summary (ADAMS Accession No. ML20155K827)
- INL/EXT-20-58327, Evaluation of Weakly Informed Priors for FLEX data, (ADAMS Accession No. ML20155K834)
- Audit Conclusion If these observations and concerns are addressed in the PWROGs updated approach, this will provide a robust basis for FLEX equipment failure probabilities.
10
Questions?
1 11 1