05000341/LER-2025-001-01, Cancellation of Licensee Event Report LER 2025-001-01, Div. 1 Transformer 64 Load Tap Changer Failure Potentially Prohibited by Technical Specifications and Potential Loss of Safety Function
| ML25272A007 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 09/26/2025 |
| From: | Banker S DTE Electric Company |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NRC-25-0038, LER 2025-001-01 | |
| Download: ML25272A007 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3412025001R01 - NRC Website | |
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Stephanie P. Banker Vice President - Engineering & Technical Support DTE Electric Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734-586-4431 Email: stephanie.banker@dteenergy.com September 26, 2025 10 CFR 50.73 NRC-25-0038 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Fermi 2 Power Plant NRC Docket No. 50-341 NRC License No. NPF-43
Subject:
Cancellation of Licensee Event Report (LER) 25-001-01, Div. 1 Transformer 64 Load Tap Changer Failure Potentially Prohibited by Technical Specifications and Potential Loss of Safety Function In accordance with NUREG-1022 Sections 2.8 and 5.1.2, DTE Electric Company (DTE) is cancelling (formally withdrawing) Licensee Event Report (LER) Number 2025-001-01, submitted to the U.S. Nuclear Regulatory Commission on August 14, 2025 (Reference 1). The LER reported, pursuant to Title 10 Code of Federal Regulations (CFR) 50.73(a)(2)(i)(B) and 50.73(a)(2)(v)(D), any condition which was prohibited by the plant¶s Technical Specifications and loss of safety function needed to mitigate the consequences of an accident. Subsequent to the submittal of LER 2025-001-01, DTE completed its reevaluation of the condition and determined that it no longer constitutes a reportable condition pursuant to 10 CFR 50.73 and NUREG-1022 guidance.
Based on an engineering evaluation, DTE determined no condition prohibited by TS occurred.
Fermi Station is required to enter a Limited Condition of Operation (LCO) per TS 3.8.1 whenever there are not two (2) qualified offsite circuits connected to the onsite AC power system and two (2) emergency diesel generators (EDGs) per division operable. The LCO CONDITION D duration is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for restoration of the offsite source with the EDGs operable but is reduced to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if an EDG is also out of service (CONDITION F). While Transformer 64 LTC was in manual mode, an offsite circuit would be qualified if the offsite voltage was high enough to maintain Division 1 Bus 64B and Bus 64C voltages above the degraded voltage relay setpoint for a postulated Loss of Coolant Accident (LOCA) event. The longest time that entered CONDITION D was 9.72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The longest period that entered CONDITION F was 9.72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Both time in conditions were less than the TS COMPLETION TIME. In summary, no condition prohibited by TS occurred.
References:
- 1) DTE Letter, NRC-25-0037, ³Licensee Event Report (LER)
No. 2025-001-00', dated August 14, 2025 (ML25226A116)
USNRC NRC-25-0038 Page 2 Based on an engineering evaluation, DTE has concluded there was no loss of safety function.
The original calculation assessing whether bus voltages could sustain emergency equipment during a postulated LOCA included significant conservatism. When that margin was removed, the analysis concluded that the bus voltages were still sufficient to support the safety function, confirming operability under actual grid conditions. Therefore, LER 2025-001-01 should be cancelled.
No new commitments are being made in this submittal.
Should you have any questions or require additional information, please contact Mr. Eric Frank, Manager-Nuclear Licensing, at (734) 586-4772.
cc: NRC Project Manager NRC Resident Office Regional Administrator, Region III Sincerely, Stephanie P. Banker Vice President - Engineering & Technical Support