ENS 46712
ENS Event | |
|---|---|
20:38 Mar 30, 2011 | |
| Title | Discovery of After-The-Fact Emergency Condition (Unusual Event) |
| Event Description | An extent of condition review of Braidwood Unit 2 unplanned loss of safety system annunciators Emergency Plan Unusual Event on March 24, 2011 (ENS 46694) was performed for both Units of Braidwood Station. During this review it was identified that a previous unknown loss of annunciators had also occurred on August 10, 2010 from 1024 to 1136 CT on Unit 2. This condition occurred during planned maintenance on annunciator cabinet 2PA19J power supply capacitors.
The maintenance performed on August 10, 2010 would normally not cause a loss of all Unit 2 annunciators. During the work, it was expected to lose approximately one third of the annunciators. Latent annunciator system problems identified from the March 24, 2011 event caused a loss of all Unit 2 annunciators and contributed to this condition being unknown to Main Control Room operators. All Unit 2 indications and computer points to the sequence of events recorder remained available and Unit 2 was stable during this timeframe. At 1538 CT on 3/30/11, it was determined that the August 10, 2010 condition met the threshold for Emergency Action Level MU6, UNPLANNED loss of most or all safety system annunciation or indication in the control room for greater than 15 minutes. This notification is being made as an undeclared Unusual Event Emergency Plan Classification per 10 CFR 50.72(a)(1)(ii). Per NUREG 1022, a 1- hour notification is required when a condition existed which met the emergency plan criteria but no emergency was declared and the basis for the emergency class no longer exists at the time of the discovery. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| Reporting | |
| Emergency class: | Unusual Event |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+-3.63 h-0.151 days <br />-0.0216 weeks <br />-0.00497 months <br />) | |
| Opened: | Mike Deboard 17:00 Mar 30, 2011 |
| NRC Officer: | Vince Klco |
| Last Updated: | Mar 30, 2011 |
| 46712 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 528022017-06-12T14:14:00012 June 2017 14:14:00
[Table view]Other Unspec Reqmnt, 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification for Discharge of Circulating Water ENS 476372012-02-03T06:00:0003 February 2012 06:00:00 Other Unspec Reqmnt ENS 467122011-03-30T20:38:00030 March 2011 20:38:00 Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition (Unusual Event) ENS 421872005-12-02T23:00:0002 December 2005 23:00:00 Other Unspec Reqmnt Reactor Power Operation in Excess of Operating License Condition ENS 405592004-03-01T22:00:0001 March 2004 22:00:00 Other Unspec Reqmnt 24-Hour Condition of License Report Involving Potential Violation of Maximum Power Level ENS 401302003-09-03T12:30:0003 September 2003 12:30:00 Other Unspec Reqmnt 24-Hour Report Required by License Condition -- Potential Violation of Maximum Power Level ENS 401232003-08-31T06:32:00031 August 2003 06:32:00 Other Unspec Reqmnt 24-Hour Condition of License Report Involving Potential Violation of Maximum Power Level 2017-06-12T14:14:00 | |