ENS 46739
ENS Event | |
|---|---|
23:07 Apr 7, 2011 | |
| Title | Unusual Event Declared Due to Hydrogen Burn During Maintenance |
| Event Description | [The licensee declared an Unusual Event at 1607 PDT due to a] small hydrogen burn when opening the stator cooling water system for maintenance. There were no injuries or equipment damage.
The licensee entered EAL 93U3 'Toxic Gases inside the Protected Area Boundary.' The licensee notified state/local agencies and will inform the NRC Resident Inspector. The licensee plans to issue a press release.
[At 2053 PDT,] Columbia has terminated the Unusual Event declared at 1607 [PDT] on 04/07/11. Conditions throughout the plant have remained stable. Columbia has confirmed there is no hazard to personnel safety nor a challenge to safe plant operation. The licensee will notify the NRC Resident Inspector. Notified R4DO (OKeefe), NRR EO (Blount), IRD (Grant), DHS (Jenkins), and FEMA (O'Connell).
At 1922 EDT on April 7, 2011, NRC was notified of an Unusual Event at Columbia Generating Station (EN#46739), The NRC was notified the event was terminated at 2353 EDT on April 7, 2011. Based on further investigation, this event is being retracted. The stator cooling water system contains a mixture of water and hydrogen when in operation. The system had been removed from service, drained and blanketed with nitrogen prior to commencing maintenance. There was no active source of hydrogen in the system. Although the system had been tested for hydrogen and none was detected, the event occurred when workers cut into a section of the system piping where a small amount of residual hydrogen remained. Immediately following the event, tape was placed over the cut to prevent any debris from entering the pipe. Hydrogen measurements were taken in the vicinity of the cut section of pipe and in the general area and concentrations were below hazardous levels. The only elevated reading occurred directly at the cut location when the tape was removed, This indicated that hydrogen, residual in nature, was confined to the inside of the pipe. Since the system was not in use and the residual hydrogen was confined, plant operations were not affected, As a result of this event, no personnel were injured, no equipment was damaged, and there was no impact to structures needed for plant operation. The licensee will notify the NRC Resident Inspector, the media, and local, state, and other government agencies of this update. Notified R4DO(O'Keefe) |
| Where | |
|---|---|
Columbia Generating Station  Washington (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.75 h-0.156 days <br />-0.0223 weeks <br />-0.00514 months <br />) | |
| Opened: | Tom Steckler 19:22 Apr 7, 2011 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Apr 8, 2011 |
| 46739 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 467392011-04-07T23:07:0007 April 2011 23:07:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Hydrogen Burn During Maintenance ENS 452452009-08-05T14:50:0005 August 2009 14:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Toxic Gas from a Switchgear Fire in the Turbine Building ENS 451692009-06-27T03:05:00027 June 2009 03:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Based on Fire Lasting Greater than 15 Minutes ENS 432902007-04-07T20:44:0007 April 2007 20:44:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Fire in the Reactor Protection System Division 2 Equipment Room ENS 424502006-03-28T21:57:00028 March 2006 21:57:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Range Brush Fire Near Plant ENS 417922005-06-24T06:21:00024 June 2005 06:21:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Licensee Declared an Unusual Event Due to Detection of a Flammable Gas in the General Services Building ENS 415652005-04-06T00:12:0006 April 2005 00:12:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Under E.A.L. 9-3.U.1 ENS 409102004-07-30T17:00:00030 July 2004 17:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared at Columbia Generating Station 2011-04-07T23:07:00 | |