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At 0519 EST on November 27, 2021, with Uni … At 0519 EST on November 27, 2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Emergency AC Electrical Power System occurred. The reason for the Emergency AC Electrical Power System auto-start was a lockout of the CT-2 transformer; causing a temporary loss of AC power to the main feeder bus. The Keowee Hydroelectric Units 1 and 2 automatically started as designed when a main feeder bus undervoltage signal was received.</br>This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Emergency AC Electrical Power System. </br>Additionally, the temporary loss of AC power resulted in a loss of Decay Heat Removal (DHR) that was restored upon power restoration to the main feeder bus. Therefore, this condition is also being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v) for an event or condition that could have prevented fulfillment of a safety function.</br>There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.</br>The loss of the CT-2 transformer is under investigation. Main feeder bus power was restored within a minute so no plant heat up occurred as a result of the loss of the decay heat removal system.the loss of the decay heat removal system. +
10:19:00, 27 November 2021 +
55,612 +
13:16:00, 27 November 2021 +
10:19:00, 27 November 2021 +
At 0519 EST on November 27, 2021, with Uni … At 0519 EST on November 27, 2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Emergency AC Electrical Power System occurred. The reason for the Emergency AC Electrical Power System auto-start was a lockout of the CT-2 transformer; causing a temporary loss of AC power to the main feeder bus. The Keowee Hydroelectric Units 1 and 2 automatically started as designed when a main feeder bus undervoltage signal was received.</br>This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Emergency AC Electrical Power System. </br>Additionally, the temporary loss of AC power resulted in a loss of Decay Heat Removal (DHR) that was restored upon power restoration to the main feeder bus. Therefore, this condition is also being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v) for an event or condition that could have prevented fulfillment of a safety function.</br>There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.</br>The loss of the CT-2 transformer is under investigation. Main feeder bus power was restored within a minute so no plant heat up occurred as a result of the loss of the decay heat removal system.the loss of the decay heat removal system. +
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00:00:00, 27 November 2021 +
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10:19:00, 27 November 2021 +
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