Power Failure Shuts Down NC Nuke

Monday, February 27, 2012 @ 03:02 PM gHale

After a disruption in the electricity supply, Progress Energy shut down Unit 1 of the Brunswick Nuclear Plant.

An electrical connector – or bus – providing power for non-nuclear systems for both of the plant’s nuclear reactors failed shortly before 7 p.m. Wednesday, the company told the Nuclear Regulatory Commission (NRC).

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One of the systems that lost power maintains pressure in the emergency core cooling systems for both reactors, Mosier said.

The loss of power to this system resulted in a low discharge pressure alarm for both units, requiring shutdown of the reactors starting a few minutes after the initial failure, the event report stated.

After about four hours, temporary power went to both cooling systems, allowing the shutdown of Unit 2 to terminate and the unit to return to full power.

The shutdown of Unit 1 continued, because the power failure also resulted in a loss of circulating water intake pumps on that reactor, the company report continued.

Mosier said the investigation into the cause of the fault is ongoing, but an initial inspection revealed signs of a transformer overheating.

Thursday afternoon the plant staff was working to replace the transformer and the bus that failed, Mosier said. Although they reported the incident to federal regulators, no emergency action levels triggered.

At that time, he said Unit 1 was in hot shutdown. Unit 2 was at full power.

Progress Energy does “not expect problems meeting customer energy demand with other generating resources,” Mosier said.

The Southport power plant’s Unit 2 is capable of generating 920 megawatts of power while Unit 1 produces 938 megawatts.

The biennial refueling of Unit 1 should begin in a week or two, Mosier said, adding the company should be on track “if our current repair plans do not impact the schedule.”



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