PNO-III-13-008, Clinton Manual Scram Following Transformer Failure
| ML13346A964 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 12/13/2013 |
| From: | Christine Lipa NRC/RGN-III/DRP/B1 |
| To: | |
| References | |
| PNO-III-13-008 | |
| Download: ML13346A964 (1) | |
PRELIMINARY NOTIFICATION December 13, 2013 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-13-008 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 and is basically all that is known by the Region III staff on this date.
Facility Licensee Emergency Classification Clinton Power Station
___ Notification of Unusual Event Exelon Generation Co., LLC
___ Alert Clinton, Illinois
___ Site Area Emergency Docket: 50-461
___ General Emergency License No. NPF-62 X Not Applicable
SUBJECT:
CLINTON MANUAL SCRAM FOLLOWING TRANSFORMER FAILURE On December 8, 2013, control room operators at Clinton Power Station received several alarms in the control room that indicated a loss of alternating current power on division 1 of the stations Class 1E electrical system. This loss of alternating current power was caused by a fault on the 4160 volt to 480 volt step-down transformer for division 1. Nonsafety-related instrument air was isolated to the primary containment due to the loss of 480 volt power on division 1. Operators manually shutdown the reactor when the scram air header pressure decreased due to loss of instrument air.
Since 480 volt equipment in division 1 no longer had a power source, several components were rendered inoperable, including low pressure core spray, the A train of residual heat removal, and the reactor core isolation cooling system. The equipment powered by divisions 2 and 3 remained operable, and the plant was shutdown safely. There was no impact on public safety.
Region III dispatched a Special Inspection Team to the site to understand the facts surrounding the event. The licensee has made repairs and is currently in the process of returning to full power operation. NRC inspectors will continue to review the licensees actions.
The State of Illinois has been informed.
This preliminary notification is issued for information only.
The information presented herein has been discussed with the licensee, and is current as of 9:00 a.m. Central Standard Time, December 13, 2013.
ADAMS Accession Number: ML13346A964
Contact:
Christine Lipa 630-829-9703 Christine.Lipa@nrc.gov