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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 August 20, 2012 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE
- PNO-lll-12-008A 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 Prairie Island Nuclear Generating Plant, Unit 1 Notification of Unusual Event Northern States Power Company, Minnesota Alert Welch, Minnesota Site Area Emergency Docket No: 50-282 General Emergency License No: DPR-42 X Not Applicable
SUBJECT:
UPDATE TO PRAIRIE ISLAND UNIT 1 UNPLANNED SHUTDOWN DUE TO BOTH EMERGENCY DIESEL GENERATORS BEING DECLARED INOPERABLE
==
Description:==
On August 14, 2012, at 04:30 a.m. CDT, Prairie Island Unit 1 commenced a reactor shutdown due to both emergency diesel generators being declared inoperable. Unit 1 has two emergency diesel generators; each generator is capable of supplying electrical power to plant equipment in the event of a loss of offsite electrical power. Both generators were declared inoperable due to evidence of a small candle sized flame on each diesel occurring during testing. Unit 2 was unaffected by this event.
Prior to the shutdown, the licensee had taken one of the switchyard transformers out-of-service for planned maintenance. This transformer supplied power to non-safety related equipment normally used to cool the reactor during full power operation. While the transformer was out-of-service, power to these pumps was being provided by the main generator. Essentially, some of the electricity being produced by the plant was used to supply power to the pumps while the rest was sent out onto the offsite grid. Offsite power to the safety-related equipment was still available via an alternate transformer.
Once the reactor was shutdown, the main generator was unable to provide power to the non-safety related pumps. This required the plant to use the safety-related, backup systems (which were being supplied by offsite power) to continue cooling the reactor. This is an allowable method in which the auxiliary feedwater pumps are used to supply non-radioactive water to the steam generators and the non-radioactive steam from the generators is released to the atmosphere.
Unit 1 was restarted on August 20, 2012. The resident inspectors monitored the repair and restoration of the diesel generators and observed the plant restart.
This preliminary notification is issued for information only. State and local officials have been informed. The site issued a press release on August 14, 2012, describing the event.
The information presented herein has been discussed with the licensee, and is current as of 9:00 a.m. CDT, on August 21, 2012. This preliminary notification is issued for information only and no further action by the staff is anticipated.
ADAMS Accession Number: ML12234A638 CONTACT: Nirodh Shah 630-829-9821 Nirodh.Shah@nrc.gov
