The groups warned of the lawsuit last week. Their concerns gained momentum after U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko voted against the Vogtle project, saying he could not get his fellow commissioners to commit to including certain post-Fukushima safety rules in the license agreement.
A Southern spokesman said the company "fully accepts responsibility" to build and operate the reactors safely.
"We are confident that the agency fully complied with the federal regulatory requirements in approving and issuing the license and see no cause to delay construction under the [combined operating license], said Steve Higginbottom, a Southern spokesman.
Georgia Power, a subsidiary of Atlanta-based Southern, is building the reactors with a group of municipal and cooperative utilities. The company is responsible for $6.1 billion of the estimated $14 billion project.
The federal government has awarded the project $8.3 billion in conditional federal loan guarantees, and Georgia Power's customers are paying down the financial costs of the project with a fee on monthly bills.
Both moves shift the financial risk of building the reactors away from Southern's shareholders and onto U.S. taxpayers and Georgia Power customers.
Georgia Power must file construction cost and scheduling reports with the state Public Service Commission every six months. An independent project monitor pointed out 12 issues in one of the reports to the Public Service Commission that could change the cost of the project, but that information in the document is redacted in the version released.
NC Warn's Warren has accused Southern of "deliberately covering up" the information. Georgia Power said the redacted information is deemed a trade secret.