ENS 48414: Difference between revisions

v t e ENS Event
03:30 Oct 17, 2012
Title	All Four Emergency Diesel Generators Auto-Start on Valid Undervoltage Signal
Event Description	On October 16, 2012, Watts Bar Nuclear Plant Unit 1 experienced a momentary loss of power to the 1B 6.9 KV Shutdown board. This resulted in an emergency start of all 4 Emergency Diesel Generators due to actuation of the designed undervoltage EDG start signal. A manual transfer of the shutdown board from the Normal power supply to the Alternate was in progress to support maintenance. The momentary loss of power lasted approximately 2 seconds, which caused load shed and Diesel Generator start to occur. Core cooling was maintained throughout the transient. This condition is being reported under 10 CFR 50.72 (b)(3) (iv) (A). All safety systems responded as designed. The unit remains stable in Mode 5. The cause for this failure is not yet known. Investigation is in progress. The NRC Senior Resident has been notified.

ENS 48414 +/-
Where
Watts Bar Tennessee (NRC Region 2)
Reporting

10 CFR 50.72(b)(3)(iv)(A), System Actuation
Time - Person (Reporting Time:+2.27 h0.0946 days <br />0.0135 weeks <br />0.00311 months <br />)
Opened:	Michael Bottorff 05:46 Oct 17, 2012
NRC Officer:	Howie Crouch
Last Updated:	Oct 17, 2012
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v • d • e

v t e Emergency Notification System
Watts Bar with 10 CFR 50.72(b)(3)(iv)(A), System Actuation
WEEKMONTHYEAR2024-07-08T19:21:00 [Table view]
[ENS list for Watts Bar]

@@ Line 16: / Line 16: @@
 | event date = 10/16/2012 23:30 EDT
 | last update date = 10/17/2012
-| title = All Four Emergency Diesel Generators Auto-Start On Valid Undervoltage Signal
+| title = All Four Emergency Diesel Generators Auto-Start on Valid Undervoltage Signal
 | event text = On October 16, 2012, Watts Bar Nuclear Plant Unit 1 experienced a momentary loss of power to the 1B 6.9 KV Shutdown board. This resulted in an emergency start of all 4 Emergency Diesel Generators due to actuation of the designed undervoltage EDG start signal.  A manual transfer of the shutdown board from the Normal power supply to the Alternate was in progress to support maintenance.  The momentary loss of power lasted approximately 2 seconds, which caused load shed and Diesel Generator start to occur.
 Core cooling was maintained throughout the transient.

Latest revision as of 22:02, 1 March 2018