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Category:NRC Preliminary Notification of Event/Occurrence
MONTHYEARPNO-III-23-002B, Prairie Island Update to PNO-III-23-002 Declaration of an Unusual Event Following a Turbine Generator and Reactor Trip Due to Fault on Unit 2 Generator Main Transformer2023-06-0808 June 2023
PNO-III-23-002B Prairie Island Update to PNO-III-23-002 Declaration of an Unusual Event Following a Turbine Generator and Reactor Trip Due to Fault on Unit 2 Generator Main Transformer
PNO-III-23-002, Prairie Island Nuclear Power Station Declaration of an Unusual Event Following a Turbine Generator and Reactor Trip Due to Fault on Unit 2 Generator Main Transformer2023-06-0101 June 2023
PNO-III-23-002 - Prairie Island Nuclear Power Station Declaration of an Unusual Event Following a Turbine Generator and Reactor Trip Due to Fault on Unit 2 Generator Main Transformer
PNO-III-15-011, Prairie Island Nuclear Plant: Shutdown of Unit 2 and Notice of Unusual Event2015-12-18018 December 2015
PNO-III-15-011 - Prairie Island Nuclear Plant: Shutdown of Unit 2 and Notice of Unusual Event
PNO-III-15-008, Prairie Island Unit 2 Shutdown Due to Trip of Main Power Turbine2015-06-0909 June 2015
PNO-III-15-008: Prairie Island Unit 2 Shutdown Due to Trip of Main Power Turbine
PNO-III-15-003, A: Update: Shutdown of Prairie Island Unit 2 Due to Loss of Instrument Air to Containment Building2015-03-26026 March 2015
PNO-III-15-003A: Update: Shutdown of Prairie Island Unit 2 Due to Loss of Instrument Air to Containment Building
ML15069A1852015-03-10010 March 2015
PNO-III-15-003 Prairie Island Nuclear Plant: Shutdown of Prairie Island Unit 2 Due to Loss of Instrument Air to Containment Building and Notification of Unusual Event
PNO-III-15-001, A: Update: Shutdown of Prairie Island Unit 1 Due to Increasing Trend in Reactor Coolant System Leakage2015-02-17017 February 2015
PNO-III-15-001A: Update: Shutdown of Prairie Island Unit 1 Due to Increasing Trend in Reactor Coolant System Leakage
ML15028A0232015-01-27027 January 2015
PNO-III-15-001 - Shutdown of Prairie Island Unit 1 Due to Increasing Trend in Reactor Coolant System Leakage
PNO-III-14-012, A Update: Shutdown of Prairie Island Unit 1 Due to Increasing Trend in Reactor Coolant System Leakage2014-12-29029 December 2014
PNO-III-14-012A Update: Shutdown of Prairie Island Unit 1 Due to Increasing Trend in Reactor Coolant System Leakage
ML14346A4682014-12-12012 December 2014
PNO-III-14-012 Shutdown of Prairie Island Unit 1 Due to Increasing Trend in Reactor Coolant System Leakage
PNO-III-12-014, Notification of Unusual Event at Prairie Island Nuclear Generating Plant2012-11-0101 November 2012
PNO-III-12-014, Notification of Unusual Event at Prairie Island Nuclear Generating Plant
ML12234A6382012-08-20020 August 2012
Update to Prairie Island Unit 1 Unplanned Shutdown Due to Both Emergency Diesel Generators Being Declared Inoperable
ML12229A3572012-08-16016 August 2012
PNO-lll-12-008 - Prairie Island, Unit 1 Unplanned Shutdown Due to Both Emergency Diesel Generators Being Declared Inoperable
PNO-III-11-013, A, Prairie Island Unit 2 Unplanned Shutdown for Greater than 72 Hours (Update)2011-10-20020 October 2011
PNO-III-11-013A, Prairie Island Unit 2 Unplanned Shutdown for Greater than 72 Hours (Update)
ML1127804832011-10-0505 October 2011
PNO-III-11-013 - Prairie Island Unit 2 Unplanned Shutdown for Greater than 72 Hours
PNO-III-10-002, Prairie Island Units 1 and 2, Fire in a Nonsafety-Related Diesel Generator2010-01-21021 January 2010
PNO-III-10-002, Prairie Island Units 1 and 2, Fire in a Nonsafety-Related Diesel Generator
PNO-III-09-003, Prairie Island - Unplanned Unit 1 Shutdown Greater than 72 Hours2009-05-20020 May 2009
PNO-III-09-003: Prairie Island - Unplanned Unit 1 Shutdown Greater than 72 Hours
PNO-III-08-007, A - Prairie Island, Unplanned Unit 1 Shutdown Greater than 72 Hours (Update)/ Notification of Unusual Event Due to a Release of a Toxic Gas Deemed Detrimental to Normal Operation of the Plant2008-08-0404 August 2008
PNO-III-08-007A - Prairie Island, Unplanned Unit 1 Shutdown Greater than 72 Hours (Update)/ Notification of Unusual Event Due to a Release of a Toxic Gas Deemed Detrimental to Normal Operation of the Plant
ML0821408742008-08-0101 August 2008
PNO-III-08-007, Prairie Island Unit 1, Unplanned Unit 1 Shutdown Greater than 72 Hours/Special Inspection
PNO-III-07-016, Prairie Island, Unplanned Unit 1 Shutdown Greater than 72 Hours2007-12-26026 December 2007
PNO-III-07-016: Prairie Island, Unplanned Unit 1 Shutdown Greater than 72 Hours
PNO-III-07-005, Prairie Island Non-Credible Bomb Threat2007-03-20020 March 2007
PNO-III-07-005 - Prairie Island Non-Credible Bomb Threat
PNO-III-06-003, Prairie Island Technical Specification Required Shutdown of Unit 2 for Greater than 72 Hours2006-02-0606 February 2006
PNO-III-06-003, Prairie Island Technical Specification Required Shutdown of Unit 2 for Greater than 72 Hours
PNO-III-05-009, Technical Specification Required Shutdown of Prairie Island Unit 2 for Greater than 72 Hours2005-04-20020 April 2005
PNO-III-05-009, Technical Specification Required Shutdown of Prairie Island Unit 2 for Greater than 72 Hours
2023-06-08
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PRELIMINARY NOTIFICATION - REGION III June 8, 2023 UPDATE TO PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -
PNO-III-23-002B 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 Xcel Energy X Notification of Unusual Event Prairie Island Nuclear Generating Plant Alert Welch, MN Site Area Emergency Docket: 05000306 General Emergency
__ Not Applicable
SUBJECT:
UPDATE TO PNO-III-23-002 DECLARATION OF AN UNUSUAL EVENT FOLLOWING A TURBINE GENERATOR AND REACTOR TRIP DUE TO FAULT ON UNIT 2 GENERATOR MAIN TRANSFORMER This is an update to the May 27 reactor trip and subsequent Notification of Unusual Event (NOUE) at the Prairie Island Nuclear Generating Plan per Preliminary Notification PNO-III 002 issued on June 1, 2023.
The NOUE was due to indications of a potential fire in the containment building subsequent to the Unit 2 turbine and reactor automatic trip due to a fault on the Unit 2 generator main transformer. The NOUE was terminated shortly after operators were able to confirm that no fire existed. The licensee determined that the fire alarms were caused by the electrical transient which occurred due to the fault on the Unit 2 main transformer.
Following the May 27 trip, the licensee maintained the plant in a safe and stable condition and initiated repairs to the main generator transformer.
The NRC Resident Inspectors continued to monitor the licensees repair efforts following the identification of the cause of the transformer failure. All repairs were completed, and the licensee commenced restart of the Unit 2 reactor.
On June 2, the licensee restarted the reactor and reached approximately 49 percent power.
During the restart, the licensee identified a main feed pump malfunction and initiated troubleshooting activities. On June 5, the licensee determined that a reactor shutdown was necessary to make necessary repairs to the main feed water pump. The licensee shutdown the Unit 2 reactor on June 7 at 3:33 AM CDT. The resident inspectors observed and monitored reactor shutdown and continue to follow licensee activities to implement repairs.
The State of Minnesota was initially notified of the original event by the licensee on May 27.
Region III Government Liaison Officer established communications with the States of Minnesota and Wisconsin to inform them of the latest situation and answer questions.
OFFICIAL RECORD COPY
NRC Region III, located in Lisle, IL, received notification of initial event occurrence by telephone call at 7:28 PM CDT via official event notification of the NOUE on Saturday May 27, 2023, with updates being provided daily. The subsequent plant restart and post maintenance issues were received by the resident inspectors on June 3. Repairs to the main feed pump and restart the unit are being closely monitored by the resident inspectors. The information presented herein has been discussed with the licensee and is current as of 10:50 AM CDT on June 7, 2023.
ADAMS Accession Number: ML23159A226 Contacts: Hironori Peterson (630) 829-9707 Hironori.Peterson@nrc.gov OFFICIAL RECORD COPY
