The sole remaining nuclear power plant under construction in the U.S. is facing mounting opposition from cities and lawmakers concerned about its rising costs.

A decision on the expansion of Georgia’s Alvin W. Vogtle Electric Generating Plant is expected by Monday, when its three primary owners are set to vote on whether to continue going ahead.

The project is billions of dollars over budget and years behind schedule, and expected to cost upwards of $27 billion, more than double the original price tag estimated when work began a decade ago. It has received $12 billion in federal loan guarantees, including $3.7 billion from the Trump administration last year.

Southern Co., the utility that serves as the largest owner of the project, announced last month that costs had risen by $2.2 billion, triggering the vote with the other major owners, Oglethorpe Power and the Municipal Electric Authority of Georgia.

The Vogtle plant is the only nuclear power plant under construction, or even serious consideration, in the U.S. If work on it stops, the prospects for new nuclear power in the U.S. would dim considerably and raise the question of whether the country can revitalize its nuclear industry.


On Wednesday, 20 Georgia lawmakers wrote a letter expressing “concern about the ever-escalating cost” of the power plant, under construction in Waynesboro, Ga., and seeking a cap on how much of those costs could be passed on to customers of smaller utilities. Georgia Gov. Nathan Deal, a Republican, wrote a letter in support of finishing work, offering his “full support moving this project forward.”

Earlier this month, one the biggest future expected customers of the nuclear plant, a public utility in Jacksonville, Fla., filed a lawsuit to try to back out of the deal. The utility, JEA, contracted with the Municipal Electric Authority of Georgia, known as MEAG, to buy about 10% of the plant’s new units for 20 years. Now, it argues, there are less expensive options.

On Tuesday, the JEA chairman wrote an open letter urging MEAG—a collection of 49 rural electric cooperatives and cities that operate municipal power companies—to vote against continuing with the project when it takes up the issue Friday, before the Monday vote by the three major partners.

JEA ran ads in Georgia newspapers on Wednesday, including one published in the Newnan Times-Herald that called Vogtle “a mistake that will cost you and your children for years to come.”


MEAG said in a statement that it appreciated input from state politicians, but that a decision on whether to create a cost cap would have to be decided by the Southern unit leading the project, Georgia Power.

When Southern announced last month that the Vogtle costs had risen by $2.2 billion, the company said it would not ask its customers to pay for the increase and instead took a $1 billion charge to its earnings. But as public utilities, some of the other partners have noted that they don’t have shareholders with whom to share the burden.

Georgia Power said it “has voted to move forward, and we hope the co-owners will also vote in favor to fulfill their obligation.”

If any of the three owners vote against moving ahead, the project would be imperiled. Southern’s Georgia Power owns 45.7% of the plant, while MEAG owns 22.7% and Oglethorpe roughly 30%. Another company, Dalton Utilities, owns a small share, 1.6%.


The project has faced many problems. These include design changes required by regulators following the 2011 disaster at the Fukushima nuclear plant in Japan, as well as the bankruptcy last year of Westinghouse Electric Co., which was building the facility. The economics also suffered when the price of natural gas fell, and Congress declined to pass legislation that capped carbon emissions.

Work stopped last year on the only other nuclear project under construction, the V.C. Summer plant in South Carolina, after its owners decided the rising costs didn’t justify pressing ahead to completion. The decision to abandon that project half-finished left politicians and utility companies squabbling over who should pay a $4.7 billion tab.

The Vogtle and Summer plants were designed using modular Westinghouse reactors that were supposed to be simpler to build than those in previous generations of nuclear power plants, and easier to deliver on time and on budget.

Neither aspiration turned out to be realistic, as problems arose with quality control in complex manufacturing tasks and with hiring qualified workers.

Write to Russell Gold at russell.gold@wsj.com