ML040020046
| ML040020046 | |
| Person / Time | |
|---|---|
| Issue date: | 12/23/2003 |
| From: | Tjader T NRC/NRR/DIPM/IROB |
| To: | Bradley B Nuclear Energy Institute |
| Tjader T., NRC/IROB, 415-1187 | |
| Shared Package | |
| ML033650093 | List: |
| References | |
| Download: ML040020046 (14) | |
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Risk Managed Technical Specifications Guidelines December 16, 2003 1 GOP ENCLOSURE 4
Goals of Effort
- Develop Guidelines to support a Risk-Informed Flexible AOT structure that:
. Is integrated with Maintenance Rule (a)(4)
. May be implemented by plants with robust (a)(4) programs
- Full or phased implementation
- flexibility commensurate with capability
- Improves risk management decision-making
. Doesn't require Rulemaking (No change to Part 50)
. Maintain ISTS structure
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. II . 1 Flexible AOT builds upon Existing Industry "Good Practices"
- Maintenance Rule Risk Management Process 10CFR50.65 requires utility to:
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+ (a)(1):SSCs monitored to ensure performance goals for equipment are commensurate with safety
- (a)(3):Maintenance practices periodically reviewed to ensure appropriateness of preventive maintenance activities
- (a)(4): Before performing maintenance activities licensees shall assess and manage plant risk
- NUNJARC-93 -01, Revisions 3 Section 11 provides general guidance for implementation
- Provides integrated and instantaneous risk goals
- Revision 2 of NEI guidance endorsed by RG 1.182
- Section 11 of Revision 3/Revision 2 are the same 4*
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What is the Flexible AOT?
- "Flexible AOT" includes a TS Action statement that provides for an allowable action to continue maintenance beyond the current or risk informed completion time, based on results of a contemporaneous risk assessment.
a Concept includes:
. "Front stop" analogous to current AOT/CT process
- Backstop -Maximum time beyond which plant configuration must be restored.
- Thirty day backstop N~~~K I~~~
- Covers most anticipated repairs 4 ~~~ez-~ 1
- Assures equipment restored to original design regardless of low risk importance
Why two pilots?
Single System Approach Full System Application (TSTF 424) (STP)
- Provides detailed vertical slice and
- Provides horizontal application of insights into risk assessment risk assessment over a broad
- Proof of concept to industry and NRC range of systems
- Allows phased introduction of RMTS
- Validates value of robust into plant maintenance rule application
- Provides basis and understanding for
- Available to plants with full extrapolation to a broad range of plants scope, high capability PSAs (per
- Allows for incremental integration of DG-1 122) and robust risk various RITS initiatives assessment processes.
- Implementation commensurate with PSA Capability t 4v
Role of RMTS Guidance
- Universal m Inclusive, based on industry consensus
- Similar to, and an expansion of, existing (a)(4) guidance
- Applies to all Flexible AOT applications n Intended to allow variability in implementation while capturing relevant risk insights 6
While Guidance is generic implementation may vary
- Plant design
- Plant maintenance practices
- Extent of the implementation
- All systems, all combinations
- Single Systems
- Mixture
- PSA Capability 7 g
Key Features of RMTS A. Risks ass ated with Pre-planned entries into extended AOT evaluated prior to entry.
B. Emergent Conditions Evaluated in a Time Frame consistent with Risk Impact
- On-Line Risk Assessment Typically performed in under < lhr Includes all systems models and multiple trains of TS equipment Or
- Identify high risk operational considerations which may require expedited plant shutdown.
Provide early detection of high risk system and system combinations.
- 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> assessment limited to conditions. Not applicable to exigent shutdown Actions (based on Initiative 6)
- Pre-determined list of risk significant combinations C. Demonstration of risk acceptability beyond Front Stop
- Quantitative process with qualitative considerations Risk assessment of ICDP/ICLERP required, extent of qualitative input will be dependent on the comprehensiveness of the PSA and the ability of the PSA to model the condition under question Greater PSA scope and capability allows potential increased reliance on PSA Qualitative assessments used to bring in non-quantified factors, impact of concurrent maintenance activities (not modeled), grid stress etc.
Target risks to maintain activities beyond frontstop using normal work controls A I
- ICDPs/ICLERPs tracked with intent to maintain impact of beyond front stop maintenance c with intent of RG 1.174 for small impact
Key Features of RMTS D. Define RI Backstop as 30 days.
Thirty day backstop is deterministic and represents a compromise with the 90 day 50.59 allowed for temporary change.
AOTs for extended repairs based on risk and need 30 days consistent with observation that NOEDs granted by NRC typically average 14 days with longer NOEDs reaching 28 days E. Includes a Risk Informed Shutdown Decision Process Process entry triggered by Risk Assessment Guidance to shutdown will consider time to complete repair, and risk trade-offs
- Once entered basis for decision to be documented F. Regulatory Control Use of Flexible AOT to be tracked and re-evaluated annually with respect to RG 1.174
- Many High risk maintenance decisions will be subject to review via Oversight Process Maintenance rule through components in (a)(1) and (a)(3) maintenance progrg Loz_
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Key Features of RMTS G. PSA Quality
- Must be capable of performing its task. "Capability commensurate with application"
- Likely Demonstration of tool and process required prior to implementation
- Consistent with ASME Standards
- Meets intent of DG-1 122
- Peer review and issue resolution important
- Scope limitations (i.e. less than full scope PSAs) may restrict scope of implementation 10 ;@
is Benefits of Flexible AOT
- Allows plant actions to be commensurate with risk.
Focus emergent activities to repair high risk component in preference to AOT limiting component.
- Allows optimized repair strategies.
- Avoids risk of unnecessary plant shutdowns
- Allocates plant staff based on risk significance of inoperability
- Reduction in NOEDs 11
Expectations of Regulatory Process a SER for RMTS Guidance a SER for TSTF 422 including associated Topical Report a HPSI CEOG plant specific LAR Referencing approved Topical Report
Conclusions
- Risk Informed Flexible AOTs allows potential risk improvements in plant operation.
- Maintenance may be prioritized based on risk consequences as opposed to TS clocks
- Added features to assessment improve quality of risk assessment
- As a consequence of the rigid definition of OPERABILITY risk assessments may result in significant benefits without significantly altering plant risk profile
- Graded application encourages enhancement of PSA scope and capability 13
- Fewer Applications for NOEDs
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