PNP 2025-036, Milestone Schedule for Open Phase Condition Detection Implementation
| ML25150A402 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/30/2025 |
| From: | Schultheis M Holtec Palisades |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| PNP 2025-036 | |
| Download: ML25150A402 (1) | |
Text
27780 Blue Star Highway, Covert, MI 49043 PNP 2025-036 10 CFR 50.4 May 30, 2025 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Palisades Nuclear Plant Docket No. 50-255 Renewed Facility Operating License No. DPR-20
Subject:
Palisades Nuclear Plant - Milestone Schedule for Open Phase Condition Detection Implementation The U.S. Nuclear Regulatory Commission (NRC) issued NRC Bulletin 2012-01, Design Vulnerability in Electric Power Systems on July 27, 2012 (Reference 1) to request information and require a response from licenses regarding the Open Phase Condition event at Byron Station Unit 2 on January 30, 2012.
In Reference 2, Palisades Nuclear Power Plant (PNP) provided the 90 days response to NRC Bulletin 2012-01 and made plans to implement a hardware modification to eliminate the vulnerability to an undetected open phase condition on the offsite power circuits at the Palisades Nuclear Plant (PNP).
Reference 3, a proposed schedule for installing the modification was published by the Nuclear Energy Institute (NEI) in NEI 13-12 Open Phase Condition Industry Guidance Document, dated December 2013. In Reference 4 NEI issued a supplement to the NEI 13-12, Section 3, which provided guidance for use in submitting deviations and exemptions to NEI-13-12.
In Reference 5, NEI issued Revision 1 to the initiative in a letter to the NRC dated March 16, 2015. This revision extended the date for implementation of design changes to December 31, 2018.
In Reference 6, the NRC was notified that PNP would follow the NEI initiative guidance schedule. Reference 6 included a list of interim corrective actions based upon lessons learned from the events at Byron Station 2. These actions will be implemented prior to exiting no-mode and entering Mode 6.
References 7 and 8 document a change in schedule for implementation, dated December 20, 2018, and April 1, 2021.
In Reference 9, NEI issued guidance which allowed risk assessment to guide open phase condition actions. The following were considered relating to Reference 9:
PNP 2025-036 Page 3 of 3
- 5)
NEI letter to Entergy Nuclear Operations, Inc, Industry Initiative on Open Phase Condition, Revision 1 (Project Number: 689), dated March 16, 2015
- 6)
Entergy Nuclear Operations, Inc. letter to NRC, PNP 2014-007, Response to Request for Additional Information - NRC Bulletin 2012-01, dated January 30, 2014 (ADAMS Accession Number ML14034A169)
- 7)
Entergy Nuclear Operations, Inc. letter to NRC, CNRO2018-00053, Schedule Change to Open Phase Condition Detection Implementation, dated December 20, 2018 (ADAMS Accession Number ML18354A823)
- 8)
Entergy Nuclear Operations, Inc. letter to NRC, PNP 2021-017, Schedule Change to Open Phase Condition Detection Implementation, dated April 1, 2021 (ADAMS Accession Number ML21091A062)
- 9)
Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, Revision 3, dated June 6, 2019 (ADAMS Accession Number ML19163A176)
- 10)
NEI 19-02, "Guidance for Assessing Open Phase Condition Implementation Using Risk Insights," dated June 20, 2019 (ADAMS Accession Number ML19172A086)
- 11)
Holtec Decommissioning International, LLC letter to U.S. Nuclear Regulatory Commission, Application for Order Consenting to Transfer of Control of License and Approving Conforming License Amendments, dated December 6, 2023 (ADAMS Accession No. ML23340A161)
Attachments: 1)
Closure Plan Summary and Milestone Schedule for Open Phase Condition Detection Implementation
- 2)
List of Regulatory Commitments cc:
NRC Region III Regional Administrator NRC Senior Resident Inspector - Palisades Nuclear Plant NRC Project Manager - Palisades Nuclear Plant NEI Open Phase Steering Committee
1 Holtec Palisades, LLC (Holtec Palisades) is the licensed owner of PNP. Holtec Decommissioning International, LLC (HDI) is the licensed operator of PNP while the facility is in decommissioning. Pursuant to the license transfer application submitted in connection with the PNP restart (Reference 10), licensed authority will transfer from HDI to Palisades Energy, LLC (Palisades Energy) upon NRCs approval of the transition from decommissioning back to power operations. Holtec Palisades will remain the licensed owner of PNP.
PNP 2025-036 Closure Plan Summary and Milestone Schedule for Open Phase Condition Detection Implementation 1 Page Follows
Closure Plan Summary and Milestone Schedule for Open Phase Condition Detection Implementation Palisades plant design has two offsite power source transformers (EX-07 & EX-04).
Safeguards Transformer 1-1 (EX-07) normally supplies offsite power to two Class 1E safety buses. Startup Transformer 1-2 (EX-04) provides an alternate offsite power source to the same Class 1E safety buses during all modes of plant operation.
During refueling outages, one of the two transformers is removed from service for maintenance while the other fulfills GOP-14 Shutdown Cooling Operations requirements.
This is to ensure reactor core safety by the availability of an offsite power source during outage activities.
The Open Phase Detection System was installed on Startup Transformer 1-2 (EX-04) in 1R24 (fall 2015). Monitoring and software algorithm revisions were made through 1R26 (fall 2018), at which time the 345kV Rear Bus trip function was enabled.
The schedule provided below contains the major milestones for completion of the Open Phase Detection System installation on Safeguards Transformer 1-1 (EX-07) at PNP.
Milestone Milestone Completion Date1 NRC Public Meeting - Palisades Nuclear Plant Open Phase Detection Closure Plan April 29, 2025 Redevelop Design Change 2Q2027 Implement Design Change Next refueling outage Monitor Data Report 2Q2028 Final Adjustments after Monitoring Period 3Q2028 Design Change Closeout 3Q2028 Update Design Basis Information 3Q2028 1 Milestone dates are subject to change as implementation progresses.
PNP 2025-036 List of Regulatory Commitments 1 Page Follows
Regulatory Commitments This table identifies actions discussed in this letter for which, upon approval, Holtec Decommissioning International, LLC (HDI), Holtec Palisades, LLC (Holtec Palisades), or Palisades Energy, LLC (OPCO) commits to perform. Any other actions discussed in this submittal are described for the U.S. Nuclear Regulatory Commissions (NRC) information and are not commitments.
Original Commitment Type (Check One)
Scheduled Completion Date One-Time Action Continuing Compliance Demonstration of compliance with the open phase condition criteria through analysis, or identify appropriate actions required to demonstrate compliance.
X Per NEI Open Phase Condition Initiative, Palisades demonstrates compliance by fully funding and adopting the PCS2000 Solutions Open Phase Detection & Isolation system.
Implementation of the NEI (NSIAC CNO) Open Phase Condition Initiative to meet the initiative schedule for operating plants.
X The Open Phase Detection System was installed on Startup Transformer 1-2 (EX-04) in 1R24 (fall 2015).
Monitoring and software algorithm revisions were made through 1R26 (fall 2018), at which time the 345kV Rear Bus trip function was enabled.
Completion of the Open Phase Detection System installation on Safeguards Transformer 1-1 (EX-07) is scheduled for the end of 2028.
If a monitoring period was deemed necessary, completion of any design adjustments identified during the monitoring period and enabling all active actuation features needed to demonstrate compliance with the open phase condition criteria.
X Within one year after installation.