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| Entered date | Event description | |
|---|---|---|
| ENS 51484 | 20 October 2015 23:55:00 | This report is being made under 10CFR50.72(b)(3)(iv)(A) 'any event or condition that results in a valid actuation of any system listed in paragraph (b)(3)(iv)(B) of this section' due to the automatic start of 'A' and 'B' Standby Diesel Generators. The automatic start of the Standby Diesel Generators occurred on a valid bus under-voltage condition caused by severe weather (lightning strikes) in the DAEC (Duane Arnold Energy Center) area. The Standby Diesel Generator output breakers did not close onto their respective essential buses. Essential electrical buses remained powered from off-site circuits through their normal power supply transformer, 1X3 Startup Transformer, during and after the event. The Standby Diesel Generators have been returned to the standby readiness condition. Both credited off-site power circuits were available before the event and remain available after the event. The licensee notified the NRC Resident Inspector. |