ENS Event | |
|---|---|
15:18 Mar 24, 2011 | |
| Title | Unexpected Loss of Annuciators During Planned Maintenance |
| Event Description | During a planned maintenance activity on the Unit 2 main control room alarm cabinets, it was identified that all Unit 2 safety system annunciators were lost. This was identified at 1006 [CDT]. Main Control Board indicators remained functional. At 1018 [CDT], the Shift Manager declared an Unusual Event under Emergency Action Level MU6. This was due to an unplanned loss of most (approximately 75%) safety system annunciators for > 15 minutes. The planned maintenance activity was not expected to affect the amount of annunciators that were lost.
At 1030 [CST], the [planned maintenance] clearance order was cleared and power was restored to the Unit 2 annunciators. There was not transient on other plant equipment and the plant remained stable before and after this event. The cause for the unexpected loss of annunciators is not clearly understood and is still under investigation. The licensee notified the NRC Resident Inspector.
The Unusual Event was terminated at 1047 CDT on 03/24/11. All annunciators have been restored and an investigation will be conducted to determine the cause. Notified R3DO (Cameron) |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.65 h-0.152 days <br />-0.0217 weeks <br />-0.005 months <br />) | |
| Opened: | Scott Butler 11:39 Mar 24, 2011 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Mar 24, 2011 |
| 46694 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 503012014-07-24T00:30:00024 July 2014 00:30:00
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