The US Nuclear Regulatory Commission has voted to certify an amended version of the Westinghouse AP1000 reactor design, paving the way for its construction in the United States.

The amended certification, which will be incorporated into the NRC’s regulations, will be valid until February 2021. NRC said that the rule would become immediately effective once it is published in the Federal Register.

“The road to receiving Design Certification has been long and sometimes arduous,” said Aris Candris, president and CEO of Westinghouse Electric Company. “But we’ve reached our final destination…”

The design certification is good news for utilities in Georgia and South Carolina, which can now move ahead with combined construction and operating license (COL) applications for the Vogtle 3&4 and VC Summer 3&4 projects.

Southern Company, which owns 45.7% of the planned Vogtle AP1000 project though its subsidiary Georgia Power, began site preparation work for the two-unit plant in 2009. Full construction can commence at the site after the NRC issues COL, which could come early in 2012.

“The commission now has all of the technical information needed to issue the Vogtle COL,” said Thomas A. Fanning chairman, president and CEO of Southern Company. Vogtle unit 3 continues on track for operation in 2016 and unit 4 in 2017, the company said in a statement.

The NRC is currently reviewing six COL applications that reference the amended AP1000 design. Four AP1000 reactors are already under construction in China at Sanmen and Haiyang.