The four owners of the Vogtle 3&4 AP1000 project under construction near Waynesboro, Georgia have voted to continue construction of the two new reactors, after agreeing on new cost-sharing provisions.

"We are all pleased to have reached an agreement and to be moving forward with the construction of Vogtle Units 3&4 which is critical to Georgia's energy future," said the co-owners. "While there have been and will be challenges throughout this process, we remain committed to a constructive relationship with each other and are focused on reducing project risk and fulfilling our commitment to our customers."

The Vogtle expansion project is co-owned by Georgia Power (45.7%), Oglethorpe Power (30%), MEAG Power (22.7%) and Dalton Utilities (1.6%).

Under the revised ownership agreement, the three largest owners had to approve the revised budget by the end of September, or the project would have been stopped. Three of the co-owners had approved the agreement by 25 September, but Oglethorpe Power, was still to vote on whether construction at the Georgia site could continue.

Since work started on Vogtle 3&4 over a decade ago, Oglethorpe noted that the project’s partners have faced an "ongoing series of cost increases." Southern Company is now projecting an additional $2.3bn rise since December 2017.

With four years remaining on the construction schedule, Oglethorpe had been seeking to hold Southern Company accountable for its newly revised budget and let their owners be responsible for any additional amounts beyond this level.

According to the 8-K reports filed with the US Securities and Exchange Commission by Georgia Power and Oglethorpe, under the new arrangement each partner would be obliged to pay its proportionate share of construction costs to complete the reactor based on the $8.4bn estimated cost of completion filed with the Georgia Public Service Commission earlier this year, along with its share of $800m of additional construction costs.

Georgia Power would be responsible for 55.7% of any construction costs that exceed the $8.4bn estimate by $800m-$1.6bn, with the other owners accountable for the remaining 44.3% based on their ownership shares.

If costs exceed the estimate by $1.6-2.1bn, Georgia Power will be accountable for 65.7% of any construction costs, with the other owners accountable for the remainder, based on their ownership shares.

The agreement also stated that if construction costs surpass the $8.4bn estimated cost by more than $2.1 billion, "each of the other Vogtle Owners would have a one-time option to tender a portion of its ownership interest to Georgia Power in exchange for Georgia Power's agreement to pay 100%" of the co-owners' share of the cost over the $8.4 billion cap.

“Georgia Power would also the option of cancelling the project in lieu of purchasing a portion of the ownership interest of any other co-owner.”

Vogtle 3&4 are the first new nuclear units to be built in the United States for more than three decades. Vogtle 3 is expected to come online in November 2021, with Vogtle 4 in November 2022.