ATLANTA (AP) — A utility says a first-of-its-kind nuclear plant under construction in eastern Georgia will go over budget.

Atlanta-based Southern Co. said Thursday that finishing Plant Vogtle (VOH’-gohl) will now cost an estimated $6.85 billion, up from $6.11 billion.

The firm also moved back the completion dates for the massive project. While the two reactors at the plant were supposed to start producing power in April 2016 and April 2017, those dates have now shifted to late 2017 and late 2018.

Utility officials say completing the nuclear plant remains cheaper than the alternatives.

Georgia’s Public Service Commission must ultimately decide whether to approve the new budget.

Plant Vogtle is one of three U.S. nuclear plants under construction. The nuclear industry has struggled historically to meet construction budgets.