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Category:NRC Preliminary Notification of Event/Occurrence
MONTHYEARPNO-III-22-001, Dresden Nuclear Power Station, Unit 3, Unplanned Shutdown Greater than 72 Hours and Notice of Unusual Event for a Fire Affecting the Main Power Transformer2021-10-19019 October 2021
PNO-III-22-001 Dresden Nuclear Power Station, Unit 3, Unplanned Shutdown Greater than 72 Hours and Notice of Unusual Event for a Fire Affecting the Main Power Transformer
PNO-III-15-004, Byron Unit 1 Automatic Shutdown After Falling Ice Caused Main Power Transformer Short Circuit2015-03-10010 March 2015
PNO-III-15-004 - Byron Unit 1 Automatic Shutdown After Falling Ice Caused Main Power Transformer Short Circuit
PNO-III-15-002, Dresden Unit 2 Shutdown2015-02-11011 February 2015
PNO-III-15-002 Dresden Unit 2 Shutdown
PNO-III-14-006, Dresden, Unit 2 and Unit 3, Report of Tritium at Dresden Sewage Treatment Plant2014-06-11011 June 2014
PNO-III-14-006, Dresden, Unit 2 and Unit 3, Report of Tritium at Dresden Sewage Treatment Plant
ML14120A1602014-04-29029 April 2014
Update to Dresden, Unit 2, Shutdown Due to Main Transformer Damage
PNO-III-14-005, Dresden Unit 2 Shutdown Due to Main Transformer Damage2014-04-15015 April 2014
PNO-III-14-005 Dresden Unit 2 Shutdown Due to Main Transformer Damage
PNO-III-12-010, A - Update-Unplanned Shutdown Greater than 72 Hours on August 30, 2012, Due to Circulating Water System Vacuum Vent Line Failure2012-09-0707 September 2012
PNO-III-12-010A - Update-Unplanned Shutdown Greater than 72 Hours on August 30, 2012, Due to Circulating Water System Vacuum Vent Line Failure
ML12248A3962012-09-0404 September 2012
PNO-III-12-010 - Unplanned Shutdown Greater than 72 Hours on August 30, 2012, Due to Circulating Water System Vacuum Vent Line Failure
PNO-III-12-003, Byron Station Unit 1 Unplanned Shutdown for Greater than 72 Hours2012-03-14014 March 2012
PNO-III-12-003 - Byron Station Unit 1 Unplanned Shutdown for Greater than 72 Hours
PNO-III-12-002, A, (Update) Byron Unit 1 Loss of Offsite Power and Declaration of a Notice of Unusual Event2012-03-0202 March 2012
PNO-III-12-002A, (Update) Byron Unit 1 Loss of Offsite Power and Declaration of a Notice of Unusual Event
ML12060A3862012-02-29029 February 2012
PNO-III-12-002 - Byron Unit 1 Loss of Offsite Power and Declaration of a Notice of Unusual Event
PNO-III-12-001, Byron Unit 2 Restarts After a Loss of Offsite Power and Declaring a Notice of Unusual Event2012-02-0707 February 2012
PNO-III-12-001, Byron Unit 2 Restarts After a Loss of Offsite Power and Declaring a Notice of Unusual Event
PNO-III-10-015, Byron, Initiation of Reactive Inspection in Response to a Failure of the Mechanism That Cools Water Surrounding a Canister Containing Spent Fuel2010-08-31031 August 2010
PNO-III-10-015: Byron, Initiation of Reactive Inspection in Response to a Failure of the Mechanism That Cools Water Surrounding a Canister Containing Spent Fuel
PNO-III-09-004, Dresden Tritium Leakage2009-06-10010 June 2009
PNO-III-09-004: Dresden Tritium Leakage
PNO-III-08-002, A - Byron, Unit 2, Update Notice of Unusual Event Due to Loss of Offsite Power to Vital Busses2008-03-28028 March 2008
PNO-III-08-002A - Byron, Unit 2, Update Notice of Unusual Event Due to Loss of Offsite Power to Vital Busses
ML0808602592008-03-26026 March 2008
PNO-III-08-002: Byron Unit 2 Notice of Unusual Event Due to Loss of Offsite Power to Vital Busses
PNO-III-07-014, Byron Unit 1, Nitrogen Leak During Maintenance2007-11-27027 November 2007
PNO-III-07-014: Byron Unit 1, Nitrogen Leak During Maintenance
PNO-III-07-012, A - NRC Inspection Team - Update to Dual Unit Shutdown2007-10-31031 October 2007
PNO-III-07-012A - NRC Inspection Team - Update to Dual Unit Shutdown
ML0729601092007-10-23023 October 2007
PNO-III-07-012 - Both Units at Byron Shut Down Due to a Lead in Pipe
PNO-III-06-004, B: Byron, Resumption of Effluent Discharges2006-04-20020 April 2006
PNO-III-06-004B: Byron, Resumption of Effluent Discharges
ML0609006692006-03-31031 March 2006
PNO-III-06-004A Tritium Leakage (Update)
PNO-III-06-006, Byron: Unusual Event Declared Due to a Fire within the Plant Protected Area2006-02-24024 February 2006
PNO-III-06-006, Byron: Unusual Event Declared Due to a Fire within the Plant Protected Area
ML0604602112006-02-15015 February 2006
PNO-III-06-004, Tritium Leakage
ML0535503512005-12-21021 December 2005
PNO-RIII-05-017- Byron Potential Gunshot Injury to a Site Employee
PNO-III-05-012, Dresden: Shutdown Expected to Be Greater than 72 Hours to Replace the Unit 2 Main Transformer2005-09-0101 September 2005
PNO-III-05-012, Dresden: Shutdown Expected to Be Greater than 72 Hours to Replace the Unit 2 Main Transformer
PNO-III-02-030, Granting of Notice of Enforcement Discretion (NOED) to 54 Licensed Operators for Failure to Take a Comprehensive Requalification Written Examination2002-07-0505 July 2002
PNO-III-02-030 - Granting of Notice of Enforcement Discretion (NOED) to 54 Licensed Operators for Failure to Take a Comprehensive Requalification Written Examination
ML17252A9231974-02-21021 February 1974
Notification of an Explosion in the Off-Gas System on 02/20/1974 at Dresden Unit 3
2021-10-19
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February 15, 2006PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-RIII-06-004This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or publicinterest 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.FacilityDresden 2 and 3Exelon Generation Co.
Morris, Illinois Docket: 50-237 and 50-249 License: DPR-19; DPR-25 Byron 1 and 2 Exelon Generation Co.
Byron, Illinois Docket: 50-454 and 50-455 License: NPF-37; NPF-66Licensee Emergency Classification Notification of Unusual Event Alert Site Area Emergency General Emergency X Not Applicable
SUBJECT:
TRITIUM LEAKAGEDESCRIPTION:
On February 10, 2006, Exelon's Dresden Station informed the resident inspectors and Region III (Chicago) that elevated levels of tritium (the radioactive isotope of hydrogen) hadbeen measured in a monitoring well located near underground piping. The piping in the area goes from the condensate storage tank (CST) to the High Pressure Coolant Injection (HPCI) system. The pipe is located onsite.In 2004, leakage was discovered in the CST to HPCI supply line pipe. The pipe is 175 feetlong; the licensee replaced approximately 75 feet of piping where leaks had been identified in 2004. The licensee suspects that the current leak is in the 100 feet of piping that was notreplaced at that time.The sample result on February 11, 2006, was 486,000 picocuries per liter (pCi/L), on February 12, 2006, was 529,000 pCi/L, on February 13, 2006, was 680,000 pCi/L, and onFebruary 14, 2006, was 540,000 pCi/L.The pipe was isolated on February 11, 2006. The licensee plans to drain the pipe. Thelicensee had planned to replace the pipe in June 2006, but is considering an adjustment to the schedule for replacement.Also, on February 10, 2006, Exelon's Byron Station informed the resident inspectors andRegion III (Chicago) that elevated levels of tritium in water had been identified in severalvacuum breaker vaults located along the discharge piping. CONTACTS:
Mark MitchellSteven Orth630/829-9855630/829-9827 PNO-RIII-06-004-2-This piping is on plant property. The piping is approximately 2.5 miles long normally carryingnon-radioactive circulating water to the Rock River. The discharge pipe is also used for planned liquid radioactive effluent releases with effluent mixing with the discharge water. The licensee is pursuing installation of monitoring wells adjacent to the piping to determine if tritium has migrated from the vaults. The licensee sampled water in 5 vaults along the pipeline. The tritium concentrations rangedfrom 256 pCi/L to 86,000 pCi/L. Resident inspectors and Region III staff are monitoring the licensee's activities. Based oncurrent information, the effects of the leakage are localized to the immediate area.The licensee is issuing a news release regarding the tritium issues at Braidwood, Byron, andDresden and announcing program for tritium assessment at all 10 of the Exelon Nuclear Generating sites.The State of Illinois has been notified. The information in this preliminary notification has beenreviewed with licensee management and is current as of 9 a.m. on February 15, 2006.
