ML12208A090
| ML12208A090 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 07/26/2012 |
| From: | Paul Krohn Reactor Projects Region 1 Branch 4 |
| To: | |
| References | |
| PNO-I-12-004A | |
| Download: ML12208A090 (2) | |
Text
Date: July 26, 2012 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-I-12-004A This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. Some of the information may not yet be fully verified or evaluated by the Region Staff.
Facility Licensee Emergency Classification Exelon Generating Company LLC.
Limerick Unit 1 Pottstown, PA Docket: 50-352 X Notification of Unusual Event
__ Alert Site Area Emergency General Emergency Not Applicable
SUBJECT:
UPDATE - NOTIFICATION OF UNUSUAL EVENT DECLARED DUE TO AN ELECTRICAL FAULT IN A NON-SAFETY RELATED TRANSFORMER; ITEM OF POTENTIAL MEDIA INTEREST On July 18, 2012 at 8:39 a.m., Exelon declared an Unusual Event (UE) at Limerick Unit 1 due to an electrical disturbance on a non-safety related transformer located in the control enclosure inside the Protected Area (PA). The disturbance was caused by a load center electrical flash over that resulted in some deformation and charring on the exterior of the transformer cabinet.
Based on the damage, the flash over met the UE criteria for an explosion within the protected area. Safety-related equipment and off-site power sources were not impacted. Exelon exited the UE at 9:46 a.m.
Exelon personnel determined that the electrical disturbance was caused by an internal fault in the non-safety related transformer. The transformer was replaced with an available on-site spare. Exelon staff conducted an extent of condition review of similar transformers in Units 1 and 2 and did not identify concerns with the transformers.
While shutdown, Exelon personnel also replaced the reactor recirculation pump shaft seals on both recirculation pumps. The primary seals on both pumps were showing signs of degrading performance.
The NRC reviewed the licensees evaluation of the cause of the electrical transient as well as corrective actions taken, and concluded the plant is safe for restart.
On July 24 Exelon personnel performed a startup of Unit 1. The unit reached full power on July 25, 2012 at approximately 5:00 p.m.
The information presented herein has been discussed with Exelon management and is current as of July 25, 2012, at 5:00 p.m.
The Commonwealth of Pennsylvania has been notified. Region I Public Affairs has been responding to media inquiries.
ADAMS Accession Number: ML12208A090 CONTACT:
Paul Krohn (610) 337-5120 Paul.krohn@nrc.gov
ML12208A090 SUNSI Review Non-Sensitive
Sensitive Publicly Available
Non-Publicly Available OFFICE RI/DRP RI/DRP RI/SLO RI/PAO RI/ORA NAME PKrohn J Clifford/gtd for NMcNamara DScrenci DLew DATE 07/26/12 07/26/12 07/26/12 07/26/12 07/26/12