The US approved its first new nuclear power reactors in decades on Thursday, despite objections from the country's top regulator that safety issues raised by last year's Fukushima meltdown were not fully addressed.

Commissioners of the Nuclear Regulatory Commission voted 4-1 to approve the construction of two 1,100 megawatt Westinghouse-Toshiba AP1000 at power generator Southern Co.'s existing nuclear facility in Vogtle, Georgia.

The dissenter was the NRC chairman, Gregory Jaczko, who argued for the need for "binding commitments" that the builders would implement design fixes to fully address risks exposed by the crisis at Japan's Fukushima nuclear plant after the March 11 earthquake-tsunami disaster.

"I cannot support issuing this license as if Fukushima has never happened... In my view that is what we are doing," he said.

In his written dissent he suggested that both the power plant builders and the NRC itself would be prone to slipping on promises and expectations to raise safety standards.

"On the day before the Fukushima accident, any nuclear professional or regulator would likely have told you that a natural disaster causing a loss of containment at three reactors simultaneously anywhere in the world was not a credible event we need be concerned about," he said.

"If nothing else, the Fukushima accident has demonstrated the potential consequences of that type of complacency."

But the other commissioners said such a commitment was not necessary and that Jaczko's concerns would be addressed.

"Imposing the license condition suggested by Chairman Jaczko would neither improve this effort nor make a difference in the operational safety of new reactors," they said in their decision.

The approval gave the go-ahead for the $14 billion project near Waynesboro, Georgia, seven years after Southern Co. first applied for permission.

Construction at the site is well under way, and Southern said the first reactor could be running by 2016 and the second a year later.

"Today is an historic day," Southern Co.'s president Thomas Fanning said after the decision.

"These two new units will set the standard for safety and efficiency in the nuclear industry."

The design of the Westinghouse reactor was approved in December after lengthy delays to address risks of terror attacks post September 11, 2001 and to address some concerns about meltdowns like those at Fukushima.

The design is supposed to be able to withstand the impact of a large aircraft being crashed into it.

It also is required to have passive shutdown capabilities in case of disaster. In Fukushima the reactors failed to shut down, and evacuated workers could not manually stop them, after a loss of external power prevented the reactors' cooling system from working.

The result was the worst disaster in the nuclear industry since Chernobyl in 1986, with blasts, fires and reactor meltdowns sending radiation levels in the surrounding region to extremely dangerous levels.

It also raised safety concerns over nuclear energy around the world, causing countries like Germany to begin turning away from nuclear energy.

High costs and safety worries have stifled expansion of the US nuclear power industry since Chernobyl.

The last NRC construction approval for a plant was in 1978; the last reactor to start up was in 1996.

NRC commissioner Kristine Svinicki insisted that the lessons of Fukushima were not being ignored in the approval Thursday.

"There is no amnesia, individually or collectively," she said.

The commitments Jaczko wanted "would not improve our systematic regulatory approach to these events... Nor would it make in our view any difference in the operational safety of the new reactors."

Fanning said that the company would meet Jaczko's concerns.

"The lessons of Fukushima are taken into account every day and will be taken into account for years to come," he told reporters.

"Anything that we learn from Fukushima I assure you we will bring to bear on our operations here."

He added that unlike in Fukushima the Vogtle plant was located far away from the coastline and not vulnerable to tsunamis.

"We are not in a seismically sensitive area," he added.