ATLANTA (AP) — Regulators say there's a "high probability" a nuclear plant under construction in Georgia will be delayed even longer than the three years already announced by its owners, according to an analysis obtained by The Associated Press.

Southern Co. subsidiary Georgia Power and its co-owners are building two more nuclear reactors at Plant Vogtle in eastern Georgia. A project using the same reactor design, Westinghouse Electric Co.'s AP1000, is underway at the Summer nuclear station in South Carolina, which has seen similar delays.

The first new reactor in Georgia was supposed to start operating in April 2016, with the second reactor following a year later. In January, Georgia Power announced the consortium designing and building the plant, Westinghouse and Chicago Bridge & Iron Co., expected the construction schedule would be delayed by more than three years. Those companies remain locked in a legal dispute about who should pay the resulting costs.

Those delays may prove a best-case scenario, according to an April 28 analysis by nuclear engineer William Jacobs Jr. and staff utility regulators at the Georgia Public Service Commission. The Associated Press obtained a copy of the report using Georgia's open records law.

Key deadlines set in the lengthened schedule from January had been delayed by March. For example, a two-month delay developed in the timeline to get a large section of the plant ready to be hoisted into place. The timeframe for completing concrete work on walls also slipped two months. Likewise, the deadline for installing a key protective barrier at the plant went backward three months.

Because the contractors have struggled to manage the schedule and have little track record of adapting, "additional delays have a high probability of being realized which would extend the units' in-service dates beyond the total current delay of 39 months," regulators said in the report.

Time is money in the nuclear power industry. The longer building a power plant takes, the more utility companies must pay in construction and borrowing costs. Ultimately, electric customers will pay for the plant's costs unless regulators intervene. A single day of delay will cost Georgia Power roughly $2 million, according to estimates from regulators.

Georgia Power owns a 46 percent stake in the plant and leads the development effort on behalf of its co-owners, Oglethorpe Power Corp., the Municipal Electric Authority of Georgia and the city of Dalton. Georgia Power originally expected to spend $6.1 billion on its share of the project. The latest estimates from regulators put the utility company's costs at $8.2 billion.

Executives with Georgia Power recently acknowledged the latest project schedule was slipping.

"While safe, quality, compliant construction will always be the number one focus, Company management continues to stress the importance of schedule adherence in meetings with the Contractor and provides guidance and support to the Contractor as necessary," the company wrote in a May 1 filing.

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