ML18176A042
| ML18176A042 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 06/25/2018 |
| From: | Vaughn S Nuclear Energy Institute |
| To: | Division of Inspection and Regional Support |
| Lewin A, NRR/DIRS, 415-2259 | |
| References | |
| Download: ML18176A042 (20) | |
Text
An Alternate Approach to NUMARC 93-01 Chuck Sibley (Wolf Creek)
Jenna Burr (Exelon)
Jim Zapetis (Exelon)
Mike McLain (APS)
Larry Ellgass (TVA)
Roy Linthicum (PWROG)
Steve Vaughn (NEI)
June 20, 2018
© NEI 2018. All rights reserved. For use by NEI members only.
Outline
- Background
- Purpose
- Proposed Changes
- Overall Process
- Proposed Pilot Effort
- Challenges
- Project Schedule
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=
Background===
- Delivering the Nuclear Promise Initiative (early 2017)
- Focus resources on high safety significant functions
- Gain efficiencies in the interface between the Maintenance Rule program and other station programs
- Leverage improvements in data collection/analysis and system monitoring
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Purpose
- Provide members with a risk-informed framework that supports the implementation and monitoring of a maintenance effectiveness program that complies with 10 CFR 50.65, effectively and efficiently leverages utility resources, and is focused on equipment performance commensurate with safety.
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Proposed Changes
- Leverage the effectiveness of maintenance strategies and lessons learned from the equipment reliability process
- Address every High Safety Significant functional failure in near real time
- Trend Low Safety Significant failures in CAP and evaluate in the (a)(3) assessment
- Leverage the (a)(4) configuration risk management program (i.e.,
CDF Trending) for unavailability insights during the (a)(3) assessment
- Consider using the Birnbaum importance measure as an additional tool in determining safety significance
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Proposed Changes
- Perform causal evaluations commensurate with safety
- All HSS functional failures and Plant Level Events warrant a near real time causal evaluation
- A trend of low safety significant failures warrants an appropriate causal evaluation.
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Overall Process - The Start
- Scoping
- Safety Significance Determination
- Establish HSS and LSS functions/SSCs considering insights from the Birnbaum importance measure (evaluated during pilot)
- Establish/Implement Maintenance Strategy
- Currently well-established equipment reliability program
- (a)(1)-(a)(2) Determination
- Based on the effectiveness of the component-specific maintenance strategy
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Overall Process - Steady State
- (a)(1)-(a)(2) Determination
- Based on the effectiveness of the component-specific maintenance strategy
- (a)(1)
- Components that are not currently effectively controlled via effective maintenance strategy
- (a)(2)
- Components that are currently effectively controlled via effective maintenance strategy
- Perform Maintenance Strategy
- Execute the defined maintenance strategy
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Overall Process - Reacting to Failures - Part I
- Issue Report (IR)/Condition Report (CR) Initiated
- If the failure is associated with an HSS SSC and is either a No Maintenance Rule Functional Yes Failure (MRFF) or a Condition Yes Monitoring Event (CME) a CAP cause evaluation is performed
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Overall Process - Reacting to Failures - Part II Yes
- LSS failures are inputs for trending under the (a)(3)
No No assessment
- HSS failures that are not MRFF or CME are inputs to determine adverse trends under the (a)(3) assessment
- If an adverse trend is identified, a Yes CAP cause evaluation is performed
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Overall Process - (a)(1) Loop
- (a)(1) process is essentially the same
- Ensure that monitoring performance to goals is focused on the effectiveness of changes to the Maintenance Strategy No Yes
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Overall Process - CDF Trending
- Core Damage Frequency (CDF)
Trending uses the (a)(4) configuration risk management process to provide unavailability Yes data for evaluation
- Both a high-level and detailed assessment of unavailability data No
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Overall Process - CDF Trending
- Actual average CDF compared to present limits
- Evaluate periods of higher risk
- Could they have been avoided?
- Indications of higher than average risk
- If evaluation results in changes to maintenance strategy, evaluate for (a)(1)
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Overall Process - Example #1
- Component: HPSI Injection Valve
- Function: Indirect Radiation Release
- Safety Significance: High
Description:
Body to bonnet leak estimated to exceed the TRM limit. Determined to be a MRFF. Cause: failure to follow work instructions resulting in an inadequate weld.
- NUMARC 93-01: Performance criteria: 3 failures, 36 months, remained in (a)(2).
- Proposed Process: (a)(1)-(a)(2) determination would consider changes to the maintenance strategy given the ineffectiveness of maintenance (inadequate weld).
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Overall Process - Example #2
- Component: Radiation Monitor RU148 (Containment Monitor)
- Function: Monitor plant radiological conditions for assessment of site boundary radiation exposure levels
- Safety Significance: Low
Description:
Monitor taken offline due to excessive spiking and several ALERT alarms - due to apparent electronic interference.
- NUMARC 93-01: Third failure against performance criteria of 4 failures in 12 months - remain in (a)(2).
- Proposed Process: LSS failure would be slated for review in (a)(3)
Assessment. CAP trending or (a)(3) review could identify or determine adverse trend.
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Overall Process - Example #3
- Component: Station Battery
- Safety Significance: HSS
Description:
Failure is unacceptable. Use condition monitoring (i.e., CME). Specific gravity and other parameters are monitored to detect adverse trends and allow corrective actions prior to failure.
- NUMARC 93-01: Criteria: 2 CMEs in 24 months.
- Proposed Process: Each battery CME has a CAP cause evaluation performed and assess for (a)(1) - (a)(2)
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Proposed Pilot Effort
- At least one pilot in each Region
- Some stations will pilot the entire MR program while others will pilot just several systems
- Pilots are not required to implement the NUMARC 93-01 process in parallel for the systems being piloted
- Pilot starts in 4th quarter 2018 or 1st quarter 2019
- Continued interactions with the staff
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Challenges
- Change management
- Impact to other station processes
- Defining responsibilities
- Other efficiencies
- Applicability of current enforcement and inspection guidance
- 50.65 is a performance-based rule
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Project Schedule
- September- Workshop/Training for pilot plants
- Fall 2018 - Pilots develop station procedures
- 4th quarter 2018/1st quarter 2019 - Begin pilot process (1 year duration)
- 1st quarter 2019 - Public meeting to review initial pilot plant results
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QUESTIONS?
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