The Nuclear Regulatory Commission greenlighted construction of the first new nuclear reactors in the United States in more than three decades Thursday.

The commission voted 4-1 to approve a license allowing construction and conditional operation of two reactors at Southern Co.’s Vogtle power plant near Waynesboro, Ga. Commission Chairman Gregory Jaczko dissented.

{mosads}The decision marks a monumental victory for the nuclear industry, which has been struggling for decades to build new reactors amid continued regulatory delays and financing problems.

“This is a historic day,” Marvin Fertel, president of the Nuclear Energy Institute, the industry’s trade group, said in a statement. “Today’s licensing action sounds a clarion call to the world that the United States recognizes the importance of expanding nuclear energy as a key component of a low-carbon energy future that is central to job creation, diversity of electricity supply and energy security.”

But the project faces major opposition from nuclear power critics, who say the project should be subject to additional environmental analysis in light of the disaster at Japan’s Fukushima Daiichi power plant.

Nine groups critical of nuclear power — including Friends of the Earth and the Southern Alliance for Clean Energy — said Wednesday that they intend to file a lawsuit challenging the decision.

Meanwhile, Thursday’s decision puts renewed attention on the Obama administration’s 2010 $8.3 billion conditional loan guarantee for construction of the new reactors, which will be built by Southern Nuclear, a subsidiary of Southern Co.

Some Democrats in Congress — noting that the loan guarantee is more than 15 times the size of the one granted to the failed solar firm Solyndra — have called on Obama not to finalize the loan.

“I think we are putting our taxpayer money at unnecessary risk given the unresolved safety issues and the lessons that have been learned from Fukushima,” Rep. Edward Markey (D-Mass.), a senior Democrat on the House Energy and Commerce Committee and a vocal critic of nuclear power, told The Hill Wednesday.

The commission is mulling new rules and procedures aimed at better protecting the country’s 104 nuclear reactors from earthquakes and floods.

A federal task force mandated by Obama in the aftermath of the Fukushima disaster called for sweeping improvements to the NRC’s “existing patchwork of regulatory requirements and other safety initiatives.”

In remarks explaining his dissent, Jaczko said the commission should not issue the license without first getting assurances that the reactor operators will take into account the lessons of the Fukushima disaster.

“I simply cannot authorize issuance of these licenses without any binding obligation that these plants will have implemented the lessons learned from the Fukushima accident before they operate,” Jaczko said in a written statement explaining his dissent.

The commission last authorized construction of a new nuclear reactor in 1978 for the Shearon Harris plant in North Carolina. The accident at the Three Mile Island power plant in Pennsylvania the next year resulted in new fears about nuclear power that greatly slowed the industry’s progress.

On Thursday, the commission approved a staff-led review of Southern Nuclear’s application. NRC Staff will issue the necessary licenses within 10 days, allowing the company to build and operate two AP1000 reactors at the existing Vogtle plant.

Southern Co. President Thomas Fanning praised the commission’s decision and argued that the federal review of the project was “thorough and complete.”

Construction of the reactors will create 4,000 to 5,000 jobs, Fanning said.

He also said the company has learned from the Fukushima disaster.

“The events of Fukushima are taken into account every day and they’ll be taken into account for years to come,” Fanning told reporters Thursday afternoon.

—This story was updated at 12:46 p.m., 1:47 p.m. and 2:11 p.m.