ATLANTA (AP) — One of the owners of a nuclear power plant being expanded in Georgia says it’s shifting costs to Georgia Power Co. in exchange for giving up a sliver of its ownership.

Oglethorpe Power Corp said Saturday that it had exercised a contractual option to freeze its costs for Plant Vogtle at $8.1 billion.

Oglethorpe provides power to 38 Georgia electric cooperatives. Oglethorpe says the move will save members at least $400 million.

In exchange, Oglethorpe’s share of the two new reactors east of Augusta would fall from 30% to 28%.

Georgia Power officials have said they don’t expect regulators to approve customers paying further costs. That meaning shareholders of Georgia Power’s parent Southern Co. would pay.