ENS 52544

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v t e ENS Event
01:24 Feb 4, 2017
Title	Unanalyzed Condition Due to Unaccounted Loads in Safe Shutdown Analysis
Event Description	On February 3rd, 2017, during engineering modification reviews of electrical busses for a station switchyard transformer, electrical loads were identified on 4kV breakers that are not accounted for in the current safe shutdown analysis. Further reviews revealed the unanalyzed loads are associated with 26 cables that are routed through multiple fire zones in the Turbine Building and both Unit 1 and Unit 2 4kV rooms that have the potential to be affected from a fire event. Per NFPA 805 requirements, the cables need to be analyzed for overcurrent trip capability to demonstrate that the breakers will isolate a fault for a fire. Hourly Fire Watch tours have been established in the identified fire zones. The public health and safety is not impacted. This notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. The NRC Resident Inspector was notified. This is a late notification for the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report. * * RETRACTION PROVIDED BY ERIK LANKHEET TO JEFF ROTTON AT 1522 ON 04/04/2017 * * * The condition reported in EN# 52544 pursuant to 10 CFR 50.72(b)(3)(ii)(B) has been evaluated, and determined not to be an unanalyzed condition that significantly degraded plant safety and is being retracted. Fire Protection Engineering performed circuit analysis of the discovered loads and determined that the Fire Safety Analysis credited power supply for an established recovery action was lost due to a Turbine Building fire. This was determined to not be a significant impact to plant safety due to the availability of an alternate offsite 4kV power supply that was not impacted by this fire. Emergency Operating Procedures already contain guidance that directs operators to align the 4kV busses to this offsite power circuit and that can be accomplished within the time necessary to perform the recovery action. During periods when this offsite power circuit was removed from service over the past three years, risk was managed using the online risk management process and no additional actions would have been required for its use as the credited power source in the Fire Safety Analysis. The NRC Resident Inspector was notified of this retraction. Notified the R3DO (Skokowski).

ENS 52544 +/- *RETRACTED*
Where
Cook Michigan (NRC Region 3)
Reporting

10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
Time - Person (Reporting Time:+116.92 h4.872 days <br />0.696 weeks <br />0.16 months <br />)
Opened:	Rob Eisenman 22:19 Feb 8, 2017
NRC Officer:	Dong Park
Last Updated:	Apr 4, 2017
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v • d • e

v t e Emergency Notification System
Cook with 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition
WEEKMONTHYEAR2017-02-04T01:24:00 [Table view]
[ENS list for Cook]

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