(Bloomberg) -- Utility giant Southern Co. has launched a search to replace longtime Chief Executive Officer Tom Fanning, who plans to announce his retirement in the coming months, according to people familiar with the matter. 

Fanning, who turned 65 in March, is expected to step down by the end of the year but will likely remain with the company in some capacity, the people said, who asked not to be identified because the matter is private.

A company spokesman said no decision has been made regarding the timing of Fanning’s departure.

During a July 28 interview, the CEO acknowledged he’s been considering his succession plan and said he wanted to stay at the helm until Southern completes its long-troubled effort to expand the Vogtle nuclear plant. 

“I have it as a personal aim to guide the company through the completion of Vogtle,” said Fanning, who has been CEO since 2010. 

The project to add two new reactors at Vogtle is at least seven years behind schedule. The cost has ballooned to about $30 billion -- more than doubled from the original budget. It’s currently slated to be finished next year, with the first reactor completed by April.

Southern, based in Atlanta, Georgia, has a mandatory retirement age of 65 for executives, but the company’s board can extend that age limit based on business need. The board extended Fanning indefinitely based in part on his leadership of Vogtle, a company spokesman said. 

Fanning is among the US utility industry’s most prominent CEOs and has represented the sector on matters including national cybersercurity, nuclear power and energy policy. He has served as chair of the Federal Reserve Bank of Atlanta and the Edison Electric Institute, the US utility trade group. 

Since taking over as CEO, Fanning has steered Southern through a period of unprecedented change as new clean energy technologies and concerns about climate change disrupted the once-staid utility business. Fanning has moved the company away from its coal-heavy roots toward using more natural gas, solar and wind. 

His tenure hasn’t been without controversy. Along with the beleaguered Vogtle nuclear project, Fanning oversaw a failed $7.5 billion effort to build a clean coal facility in Mississippi. 

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