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Construction of two nuclear reactors in South Carolina was halted Monday after the project’s owners announced they were suspending work on the multibillion-dollar power plants.

The reactors, which were supposed to be operational by 2019, were among the first American nuclear power projects to be built in decades.

In statements, the utilities behind the project blamed Westinghouse, the nuclear energy company that began building the plants in 2013 but filed for bankruptcy in March.

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Unit one of the V.C. Summer Nuclear Stations near Jenkinsville, South Carolina, in 2106. Chuck Burton / AP

A Westinghouse analysis showed that the station wouldn’t be finished until 2024, according to one of the utilities, Santee Cooper.

“The best case scenario shows this project would be several years late and 75 percent more than originally planned,” Santee Cooper President and CEO Lonnie Carter said in a statement. “We simply cannot ask our customers to pay for a project that has become uneconomical.”

The utility, which owns a 45 percent share in the project, originally approved a $5.1 billion budget, most of which has been spent. Suspending construction will save ratepayers an estimated $7 billion, the statement from Santee Cooper said.

Environmental groups had asked state regulators to abandon the project and to refund the billions that utility customers paid through annual rate increases, the Associated Press reported.

The project had been heralded as an effort to kickstart a "30-years-dormant industry," Leighton Lord, chairman of Santee Cooper's board of directors, said in a statement. But its collapse signals a setback in an industry that has struggled to overcome a fear of nuclear power in the United States triggered by the meltdown at Three Mile Island in Pennsylvania in 1979.

Edwin Lyman, a senior scientist with the Global Security Program at the Union of Concerned Scientists in Washington, told Reuters that strict safety standards will cost companies billions. What happened in South Carolina, he said, should be looked at as a cautionary tale.

"Unless the nuclear industry acknowledges that there are no shortcuts to development of new nuclear power technology, it will be doomed to repeat this failure," he said.