ML25216A243
| ML25216A243 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 08/05/2025 |
| From: | Palo Verde, AZ |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML25216A235 | List: |
| References | |
| Download: ML25216A243 (1) | |
Text
Risk-Informed Process for Evaluations (RIPE) License NRC RIPE Workshop NRC Headquarters, Rockville, Maryland August 5th, 2025
Overview of RIPE Applications at Palo Verde Diverse Auxiliary Feedwater Actuation (DAFAS)
System Exemption Removal of obsolete, low-risk system Safety Injection Tank (SIT) License Amendment Request (LAR)
Extension of Completion Time from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 10 days Both submittals:
- Demonstrated minimal risk impact
- Preserved defense-in-depth
- Received NRC approval
3 DAFAS RIPE Submittal - Key Insights Defense-in-depth preserved via:
Operator training System redundancy NRC emphasized clarity on:
Manual actions Common cause failure defenses Defense-in-depth strategy
Safety Injection Tank RIPE Submittal - Key Insights Scope of PVGS SIT RIPE change well defined PVGS SIT IDP review provided value and good challenges Defense-in-depth provided by robust design bases No new risk management actions required PRA results for extending the AOTs of TS 3.5.1.B and TS 3.5.2.B from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 10 days was within the RIPE acceptance criteria
5 Palo Verde IDP Process Cross-functional teams (Ops, PRA, Engineering, Licensing)
RIPE-specific training and procedures developed Structured review with scenario walkthroughs Open participation from NRC and leadership
NRC Pre-Submittal Meetings Early engagement clarified expectations Defense-in-depth was a central focus NRC requested:
Clear exemption basis (e.g., undue hardship)
Resources associated with maintaining or replacing DAFAS was not commensurate with its safety significance, which represented an undue hardship Clarification of PRA assumptions and historical reliability data
Questions