ENS Event | |
|---|---|
05:00 Dec 16, 2025 | |
| Title | Part 21 - Emergency Diesel Generator Failure |
| Event Description | The following information was provided by the licensee via email:
This is a non-emergency notification required by 10 CFR 21.21(d)(3)(i). A written report in accordance with 10 CFR 21.21(d)(3)(ii) will be provided within 30 days. On December 16, 2025, Peach Bottom engineering staff determined that a defect identified during a causal evaluation could constitute a substantial safety hazard. Failure analysis testing of a Fairbanks Morse Defense, emergency diesel generator (EDG) engine cylinder liner documented gross delamination between layers of the cylinder liner chrome plating. The delamination and subsequent loss of chrome plating contributed to piston ring damage that enabled combustion gas leakage into the engine crankcase, tripping the EDG on high crankcase pressure. The Fairbanks Morse Defense part number: LINER, CYLINDER, KIT, F/DIESEL GEN, MOD-38TD8-1/8, is purchased as a safety related part. Peach Bottom's procurement specification requires one single layer of chrome plating which is inconsistent with the defect exhibited, 'at least two passes of chrome plating' during failure analysis. The EDG piston ring failure and ensuing inoperability resulted in the loss of a sub-component function, which could constitute a substantial safety hazard. The defect extent of condition potentially includes 5-cylinder liners with serial numbers: H837-1, H837-2, H832-2, H838-1, and H9311-2. On December 17, 2025, the Peach Bottom site Vice President was notified of the requirement to report this event under 10 CFR 21.21. The NRC Senior Resident Inspector at Peach Bottom has been notified The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: This condition effects safety related diesel generators "E-1" and "E-3". After repair of "E-1" and an operability determination on "E-3", no limiting conditions of operability were entered as a result of the defect. Limerick Generating Station is potentially affected by this defect. Fairbanks Morse Defense has also been notified. |
| Where | |
|---|---|
Peach Bottom  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+34.48 h1.437 days <br />0.205 weeks <br />0.0472 months <br />) | |
| Opened: | Tim Grimme 15:29 Dec 17, 2025 |
| NRC Officer: | Ian Howard |
| Last Updated: | Dec 17, 2025 |
| 58091 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 580912025-12-16T05:00:00016 December 2025 05:00:00
[Table view]10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - Emergency Diesel Generator Failure 2025-12-16T05:00:00 | |