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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 1, 2023 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-23-002 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:
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 On Saturday, May 27, at 6:44 p.m. CDT, the Prairie Island Nuclear Generating Plant notified the NRC of a Notification of Unusual Event (NOUE) due to indications of a potential fire in the containment building. At 6:19 p.m. CDT the Unit 2 turbine and reactor had automatically tripped due to a fault on the Unit 2 generator main transformer. At the same time as the trip, two fire alarms were received from the Unit 2 containment building. Personnel were unable to enter the Unit 2 containment to validate the fire alarms within 15 minutes; therefore, Shift Manager declared an NOUE at 6:34 p.m. CDT (EN 56543 completed at 7:20 p.m. CDT). After entry into the Unit 2 containment building, plant operators verified that there was no smoke, fire, steam, acrid odors, or elevated temperatures within the building. At 6:45 p.m. CDT, the licensee determined there was no fire. The licensee terminated the NOUE at 11:04 p.m. CDT. The licensee determined that the alarms were caused by the electrical transient which occurred due to the fault on the Unit 2 main transformer.
Following the trip, all safety systems operated as designed. Station personnel maintained the plant in a safe condition and troubleshooting is in progress to determine the cause of the main generator transformer fault and initiate any necessary repairs.
NRC Resident Inspectors responded to the site and verified that the plant was in a safe condition and that plant personnel were operating in a manner consistent with protecting the health and safety of the public.
The State of Minnesota was notified by the licensee. Region III Government Liaison Officer contacted the States of Minnesota and Wisconsin to inform them of the situation and answer questions.
The NRC resident inspectors will continue to monitor the licensees investigation and repair efforts. The resident inspectors are scheduled to observe and monitor the reactor plant restart following completion of repair activities.
OFFICIAL RECORD COPY
NRC Region III, located in Lisle, IL, received initial notification of this occurrence by telephone call at 7:28 p.m. CDT via official event notification of the NOUE on Saturday May 27, 2023, with updates being provided daily. The information presented herein has been discussed with the licensee and is current as of 4:10 p.m. CDT, May 31, 2023.
ADAMS Accession Number: ML23151A685 CONTACT: Hironori Peterson 630-829-9707 Hironori.Peterson@nrc.gov OFFICIAL RECORD COPY