PNO-III-07-016, Prairie Island, Unplanned Unit 1 Shutdown Greater than 72 Hours

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PNO-III-07-016: Prairie Island, Unplanned Unit 1 Shutdown Greater than 72 Hours
ML073601073
Person / Time
Site: Prairie Island Xcel Energy icon.png
Issue date: 12/26/2007
From: Bartleman J, Kenneth Riemer
NRC/RGN-III
To:
References
PNO-III-07-016
Download: ML073601073 (2)


December 26, 2007 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-III-07-016 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.

Facility Licensee Emergency Classification Prairie Island Unit 1 Notification of Unusual Event Nuclear Management Company (NMC) Alert Welch, Minnesota Site Area Emergency Docket: 50-282 General Emergency License: DPR-42 X Not Applicable

SUBJECT:

UNPLANNED UNIT 1 SHUTDOWN GREATER THAN 72 HOURS DESCRIPTION:

During post-maintenance testing on equipment associated with D2 Emergency Diesel Generator (EDG) and the associated Bus 16 Load Sequencer, testing was performed on the Bus 15 Load Sequencer as required by Technical Specifications to ensure the redundant bus equipment was operable. About midnight on Thursday, December 20, 2007, Bus 15 load sequencer failed its testing, and per procedure the associated D1 EDG was declared inoperable.

With both EDGs on Unit 1 inoperable, Technical Specifications required the site to begin a unit shutdown within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and be shutdown by 7:55 a.m. CDT on Friday, December 21, 2007.

Unit 1 was placed in MODE 3- HOT STANDBY about 7:05 a.m. CDT on Friday, December 21, 2007.

Upon investigation, the cause of the Bus 15 load sequencer failure was determined to be a faulty electronic circuit card. Bus 15 load sequencer was returned to service on December 21, 2007. The licensee subsequently completed maintenance and testing on D2 EDG the morning of December 24, 2007. With all required equipment for startup returned to service, the plant commenced startup of Unit 1 and returned the unit to full power at about 6:00 a.m. CDT on December 25, 2007.

The resident inspectors observed activities surrounding this shutdown; the repairs made and related testing.

The State of Minnesota will be informed.

The information in this preliminary notification has been reviewed by the licensee.

This information is current as of 2:30 p.m. CDT on December 26, 2007.

CONTACTS: Ken Riemer John Bartleman (630) 829-9628 (630) 829-9720