ML24155A211
| ML24155A211 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/07/2024 |
| From: | Arnold E Arizona Public Service Co |
| To: | William Orders NRC/NRR/DORL/LPL4 |
| Orders, William | |
| Shared Package | |
| ML24155A213 | List: |
| References | |
| Download: ML24155A211 (1) | |
Text
VRR-02:
Exercise Test Frequency reduction Eli Arnold, IST Program Owner June 7, 2024
Alternative Request Summary Current Requirements Alternative Requirements Alternative Justification Duration of Proposed Alternative Conclusion Agenda
3 Reason for the request:
Palo Verde desires to perform once-per-cycle exercise testing of select valves.
Operating cycles are 18 months, which exceeds the 3-month frequency required by ISTC-3510.
Scope - active valves with fail-safe function to close that are normally closed. No open safety function.
Alternative to requirements of ASME OM-2012 No industry precedents Alternative Request Summary
4 Current Requirements
5 Current Requirements
6 Alternative Requirements Requirements:
Amended ISTC-3510 Active category A and B valves with a safety function to close, a fail-safe function closure and no safety function in the open position, shall be exercised once per refueling cycle.
Summary:
Valves in the scope of this request shall receive formal exercise testing once per refueling cycle.
7 Normally closed Limited opportunity to be open at accident start.
The valves are only operated to support testing or specific plant evolutions All applicable procedures ensure the valves return to their normally closed position after use.
Valve design validates safety function to close Control room hand switches remove the energy source that holds the valve open, permitting passive closure via a spring.
Alternative Justification
8 Example Palo Verde already has valves tested once-per-cycle 9 AOVs and 13 SOVs, per unit ISTC-3521, Category A and Category B Valves Cold shutdown and refueling outage testing due to impracticality OM Code acknowledges once-per-cycle testing provides acceptable level of quality and safety Alternative Justification
9 The proposed alternative shall be used for the duration of Palo Verdes fourth 120-month in-service testing interval, which ends January 14, 2028.
Duration of Proposed Alternative
10
- Palo Verde can provide an acceptable level of quality and safety by performing a once-per-cycle exercise test.
- The valves are designed, operated and controlled to assure safety functions are met.
Conclusion