ML26023A068
| ML26023A068 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/29/2025 |
| From: | Arnold E Arizona Public Service Co |
| To: | Thomas Scarbrough NRC/NRR/DEX/EMIB |
| References | |
| Download: ML26023A068 (0) | |
Text
Refined OM Requirements Drive Operational Efficiencies Eli Arnold July 29, 2025
Introduction
The Alternative Requests VRR-02 & VRR-03
4 VRR-02 Permits once-per-cycle exercise test (18 months) 28 active category A & B valves per unit Code requires quarterly exercise testing Benefit:
Saves time scheduling, printing, briefing, performing, and archiving records Three procedures per unit impacted
5 VRR-03 Permits single, upper acceptance criterion Accept a wider range of stroke times as acceptable 4 SOVs per unit with reference value Code requires a tolerance band (+/-)
Benefit:
Saves time and effort Station does not need to re-test and evaluate rapid stroke times
6 VRR-02 & VRR-03 Leverage plant-specific insights to gain operational efficiencies Installed minimum recirculation flow measurement does not meet instrument accuracy requirements for quarterly safety injection pump testing The absence of inlet pressure gages on diesel fuel oil transfer pumps Long-standing relief requests
Mindset From compliance to design
8 Compliance Mindset Ensure OM Code and regulatory requirements are met Data processing IST basis information Component trending Dispositioning test deviations Respond to new regulatory requirements Examples
9 Design Mindset Look for opportunities to solve programmatic, business and resource issues Identify problems Propose solutions Research Test Iterate Examples
10 Applied Design Mindset Insight - Identify the problem. Are we over-testing some valves? Do we really need to write these evaluations?
Investigation - Research requirements, capabilities, and scope.
Feedback - Regulators review the proposal, asking clarifying questions and challenging the technical basis to ensure an acceptable level of quality and safety.
Refinement - Perform additional research to answer regulator questions and provide comprehensive technical basis.
Iteration - Regulatory review is iterative because plants must satisfy all questions to demonstrate an adequate technical basis for acceptable quality and safety.
Final approval and implementation. - NRC issues a safety evaluation. Station revises procedures and program documentation to align with the approved alternative request.
Lessons learned Technical rigor in alternative requests
12 VRR-02 Pre-submittal meeting Risk
- 19 not modeled in PRA Performance & Maintenance history
- 7% of corrective maintenance from in-service testing
- Most issues identified by non-IST inspections, operations, and maintenance Duration in the non-safety open position
- Active is consistent with NUREG-1482 guidance on active/passive functions Operational methods of verifying valve closure after use
- Control room indicating lights maintained via ISTC-3700
13 VRR-02 Requests for Additional Information
- Administrative controls
- List of operating procedures for each valve
- Shift turn-over process
- Methods of assessing operational readiness
- Operations department guides
- Corrective action program requirements
14 VRR-03 Pre-submittal meeting
- Specify applicable valves
- Reduced scope to 4 from 48
- Performance and maintenance history
- 54% of corrective maintenance work orders were for increasing stroke times and fail-to-stroke
- All others were for either program management (test condition changes) or leakage
- Relationship between shorter stroke times and stem-disc separation
- Operating Experience for pinned and SOV stem-disc connections
- Valve body too small to allow pinned connection to detach
15 Summary Pre-submittal meetings
- First avenue for regulator input Performance and maintenance history
- VRR-02 and VRR-03 Incorporate regulatory guidance from NUREG-1482 Incorporate risk impacts for changes in test frequency
Conclusion
Questions