ENS 58139
ENS Event | |
|---|---|
05:00 Dec 10, 2025 | |
| Title | Part 21 - EMD Diesel Generator Cylinder Head Cracking |
| Event Description | The following is a summary of information provided by Engine Systems, Inc. via fax:
Commercial, high duty cycle applications have experienced cracks between the core plugs and injector well on EMD cylinder heads cast from May 2023 to August 2025. The effect is a minor jacket water leak at the top of cylinder head. If the leakage goes undetected, there is the long-term possibility of lube oil dilution that could prevent the engine from fulfilling its safety-related function. Data obtained from commercial applications indicates these top deck head cracks developed in only the heaviest loaded engines and at an average of 3000 hours0.0347 days <br />0.833 hours <br />0.00496 weeks <br />0.00114 months <br />. Considering a typical EMD nuclear engine operating time of 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> per year, a cylinder head is expected to last 60 years in an emergency standby application before a crack may develop. For the few commercial applications impacted by this issue (less than 0.5 percent), cracks were detected during top deck inspections, but the leakage did not negatively affect engine operation. Crack propagation has not been a concern, and the issue is localized to the top deck area adjacent to the core plugs. The effect of the crack was nuisance leakage. If left undetected, one symptom of the leak is oil dilution. It is recommended to perform periodic top deck visual inspections of the head and continue performing lube oil analysis. Corrective actions have been implemented by the casting manufacturer effective August 2025. For future shipments, ESI will ensure all cylinder heads have a cast date after August 2025. Responsible corporate officials: Dan Roberts, Quality Manager John Kriesel, Engineering Manager Engine Systems, Inc. 175 Freight Rd Rocky Mount, NC Affected plants: Region I - Fitzpatrick, Nine Mile Point Region II - Brunswick, Sequoyah, Turkey Point, Watts Bar Region III - Davis Besse, Dresden, Perry, Quad Cities Region IV - Grand Gulf |
| Where | |
|---|---|
| Engine Systems, Inc Rocky Mount, North Carolina (NRC Region 2) | |
| Organization: | Engine Systems, Inc |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+1235.15 h51.465 days <br />7.352 weeks <br />1.692 months <br />) | |
| Opened: | Dan Roberts 16:09 Jan 30, 2026 |
| NRC Officer: | Robert A. Thompson |
| Last Updated: | Jan 30, 2026 |
| 58139 - NRC Website | |
Engine Systems, Inc with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
WEEKMONTHYEARENS 581392025-12-10T05:00:00010 December 2025 05:00:00
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