ENS 49486

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v t e ENS Event
16:17 Oct 30, 2013
Title	Postulated Fire Event That Could Adversely Impact Safe Shutdown Equipment
Event Description	A review of industry operating experience regarding the impact of unfused Direct Current (DC) ammeter circuits in the control room has determined the described condition to be applicable to the Cooper Nuclear Station resulting in a potentially unanalyzed condition with respect to 10 CFR 50 Appendix R analysis requirements. The original plant wiring design and associated analysis for the Class 1E batteries control room ampere indications do not include overcurrent protection features to limit the fault current. In the postulated event, a fire could cause one of the ammeter wires to short to ground. Simultaneously, it is postulated that the fire causes another DC wire from the opposite polarity on the same battery to also short to ground. This could cause a ground loop through the unprotected ammeter wiring. This event could result in excessive current flow (i.e., heating) in the ammeter wiring to the point of causing a secondary fire in the raceway system. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR. 50 Appendix R. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(ii)(B). Interim compensatory measures (i.e.., fire watches) have been implemented for affected areas of the plant. The licensee has notified the NRC Resident Inspector.

ENS 49486 +/-
Where
Cooper Nebraska (NRC Region 4)
Reporting

10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
LER:	05000298/LER-2013-001
Time - Person (Reporting Time:+0.43 h0.0179 days <br />0.00256 weeks <br />5.89014e-4 months <br />)
Opened:	Brian Hasselbring 16:43 Oct 30, 2013
NRC Officer:	Howie Crouch
Last Updated:	Oct 30, 2013
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v • d • e

v t e Emergency Notification System
Cooper with 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
WEEKMONTHYEAR2019-12-05T14:10:00 [Table view]
[ENS list for Cooper]

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