ENS 48463

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v t e ENS Event
11:15 Oct 31, 2012
Title	Sequencer Fault Resulting in System Actuations
Event Description	On October 31, 2012 at 0615 hours0.00712 days <br />0.171 hours <br />0.00102 weeks <br />2.340075e-4 months <br /> CDT, Unit 1 Train 'B' Safety Injection/Blackout Sequencer faulted resulting in a start of the Turbine Driven Auxiliary Feed Water (TDAFW) Pump and Train 'B' Emergency Diesel Generator (EDG). Reactor power was reduced to 97% rated thermal power (RTP) by an immediate load reduction of 50 MWe due to the resulting cooler Auxiliary Feed Water being injected into the Steam Generators; reactor power did not exceed 100% RTP. Train 'A' equipment was not affected by the event. The TDAFW Pump was secured at 0628 hours0.00727 days <br />0.174 hours <br />0.00104 weeks <br />2.38954e-4 months <br /> by closing the Train 'B' steam supply valve from the main control board and the steam supply valve was declared operable at 0916 hours0.0106 days <br />0.254 hours <br />0.00151 weeks <br />3.48538e-4 months <br /> when the hand switch was returned to 'Auto' and the control switch lineup surveillance was completed. The Train 'B' EDG was loaded to 100% capacity in accordance with the operating procedure and secured at 1032 hours0.0119 days <br />0.287 hours <br />0.00171 weeks <br />3.92676e-4 months <br />. The EDG is available but remains inoperable until the Sequencer is declared operable. Efforts continue to restore the Sequencer at this time. A faulted 15 Volt power supply was identified and further investigation/calibration will determine if other conditions contributed to the fault. A final surveillance test will determine Sequencer operability. The most limiting Shutdown Technical Specification action statement is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in accordance with Safety Injection Sequencer TS 3.8.1 F. Current projections for Sequencer operability, and thus Train 'B' EDG operability, are 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />. This action appears to be an invalid actuation. However, this will be confirmed after a cause analysis and an update to this event will be provided at that time. The licensee has notified the NRC Resident Inspector. * * UPDATE FROM ROBERT CLARK TO VINCE KLCO ON 12/20/12 AT 1130 EST * * * This is an update to Event Notification#48463. This event was initially reported on October 31, 2012 as a valid actuation per 50.72(b)(3)(iv)(A). However, further evaluation of this event has confirmed that the cause was isolated to a failed 15VDC power supply and the ESF bus voltage sensed by the Blackout Sequencer did not dip. Therefore, a valid blackout condition did not occur and the starts of the Unit 1 Turbine Driven Auxiliary Feed Water Pump (TDAFWP) and the Unit 1 Train B Emergency Diesel Generator (EDG) were both determined to be invalid. For the EDG start, the associated electrical bus was never de-energized and the EDG output breaker did not close. Therefore, the EDG start is not reportable per 10CFR50.73(a)(2)(iv)(A) since it was an invalid actuation and the safety function (i.e. provide power to the safety related electrical bus) had already been completed at the time of the EDG actuation. For the TDAFWP start, the AFW system safety function had not already been completed. Therefore, the TDAFWP start is reportable as an invalid actuation per 10CFR50.73(a)(2)(iv)(A) with the option to provide a telephone notification within 60 days instead of an LER per 10CFR50.73(a)(1). The following required information is being submitted per NUREG-1022, Rev. 2 for the TDAFWP start: (a) The specific train(s) and system(s) that were actuated - Unit 1 Turbine Driven Auxiliary Feed Water Pump. (b) Whether each train actuation was complete or partial - The train actuation was complete. (c) Whether or not the system started and functioned successfully - The system started and functioned successfully. The NRC Resident Inspector has been informed. Notified R4DO (Spitzberg).

ENS 48463 +/-
Where
Comanche Peak Texas (NRC Region 4)
Reporting

10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation
Time - Person (Reporting Time:+2.9 h0.121 days <br />0.0173 weeks <br />0.00397 months <br />)
Opened:	Michael Stakes 14:09 Oct 31, 2012
NRC Officer:	Dong Park
Last Updated:	Dec 20, 2012
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v • d • e

v t e Emergency Notification System
Comanche Peak with 10 CFR 50.73(a)(1), Submit an LER
WEEKMONTHYEAR2019-11-01T00:19:00 [Table view]
[ENS list for Comanche Peak]

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