Nuclear reactor taken offline in Georgia due to ‘valve issue’

One of the two nuclear reactors at Georgia’s Plant Vogtle has been taken offline due to a “valve issue”.

The announcement came roughly a week after Unit 3 of the reactor was powered down, according to a report in the Atlanta Journal-Constitution.

Georgia Power did not immediately reply to Fortune’s request for comment about the reactor.

Unit 3 (which is one of four reactors at the plant) shut down on July 8 when a valve that supplies feedwater to the steam generator malfunctioned. Georgia Power officials said safety systems worked as designed and there is no threat to the area or employees.

Repairs have reportedly been completed on the reactor, but officials have not said when it will come back online.

The issues with Unit 3 comes less than three months after Unit 4 went into operation, helping the state meet high demand as temperatures soar and air conditioners run regularly in homes and businesses. (Officials say they do not expect to have trouble meeting the demand, even with Unit 3 down.)

Unit 3 first went online last July. At a cost of $35 million (more than $17 million higher than projected), i was the first nuclear reactor built from the ground up in the U.S. in over 30 years. It joined two of the oldest nuclear reactors, which have been in operation since the 1980s. Construction was not a smooth process and the unit did not go into operation until nearly seven years later than expected.

Calculations show Vogtle’s electricity will never be cheaper than other sources Georgia Power could have chosen, even after the federal government reduced borrowing costs by guaranteeing repayment of $12 billion in loans, but regulators remain bullish about the two new plants.

This story was originally featured on Fortune.com