View source for PNO-III-12-018, A - Update - Unplanned Shutdown Expected to Last Greater than 72 Hours Due to Electrical Ground Detected on the Main Generator Field

{{Adams
| number = ML12347A204
| issue date = 12/12/2012
| title = PNO-III-12-018A - Update - Unplanned Shutdown Expected to Last Greater than 72 Hours Due to Electrical Ground Detected on the Main Generator Field
| author name = Ring M
| author affiliation = NRC/RGN-III/DRP/B1
| addressee name = 
| addressee affiliation = 
| docket = 05000331
| license number = DPR-049
| contact person = 
| document report number = PNO-III-12-018A
| document type = NRC Preliminary Notification of Event/Occurrence
| page count = 2
}}
{{#Wiki_filter:PRELIMINARY NOTIFICATION - REGION III December 12, 2012 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-12-018A 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 III staff.
Facility                                           Licensee Emergency Classification Duane Arnold Energy Center                             Notification of Unusual Event NextEra Energy Duane Arnold, LLC                       Alert Palo, IA                                               Site Area Emergency Docket: 50-331                                         General Emergency License: DPR-49                                      X Not Applicable

==SUBJECT:==
UPDATE - UNPLANNED SHUTDOWN EXPECTED TO LAST GREATER THAN 72 HOURS DUE TO ELECTRICAL GROUND DETECTED ON THE MAIN GENERATOR FIELD DESCRIPTION: On December 6, 2012, Duane Arnold operators commenced a reactor startup following troubleshooting and testing of the main generator. The reactor was made critical at 10:55 p.m. CST on December 6, 2012, and the main generator was synchronized to the grid at 5:08 p.m. CST on December 7, 2012. The reactor is expected to return to full power on December 12, 2012. The NRC resident inspectors observed the forced outage and restart activities.
The events that led to the shutdown described below are from PNO-III-12-018 dated December 3, 2012.
On December 1, 2012, at 3:18 p.m. CST, operators of the Duane Arnold Energy Center reactor took the main generator offline, and at 8:15 p.m. CST, shut down the reactor to investigate and repair an electrical ground that was detected on the main generator field.
On Thursday, November 29, 2012, while increasing reactor power following a scheduled refueling outage, control room operators received an alarm for a ground detected on the main generator field. Upon receiving this alarm, operators followed their alarm response procedures and attempted to identify the cause of the alarm while the main generator was online, but were unsuccessful. The licensee proceeded to take the main generator offline to perform additional tests and make repairs. The licensee plans for the reactor to be shut down for greater than 72 hours to perform these activities. The NRC resident inspectors observed the shutdown activities, and the State of Iowa has been notified.
This preliminary notification is issued for information only.

Region III received initial notification of this occurrence by a telephone call from the resident inspectors office (RIO) at approximately 7:30 a.m. CST on November 29, 2012.
The information presented herein has been discussed with the licensee, and is current as of 9:00 a.m. CST on December 12, 2012.
ADAMS Accession Number ML12347A204 CONTACT:       M. Ring (630) 829-9703 Mark.Ring@nrc.gov}}

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