"It is apparent that while little is known definitively about the cause and impacts of what occurred at Fukushima, many aspects of the accident have grave consequences for U.S. nuclear plants, including the AP1000 reactors," said the petition, filed by the AP1000 Oversight Group, comprised of 12 environmental groups.
Southern Nuclear, which plans to use the Westinghouse reactor design at Vogtle, risks potential cost overruns if it moves ahead too quickly on the $14.8 billion project, said Sara Barczak, the program director of the Southern Alliance for Clean Energy.
"The original Vogtle project was the poster child for cost overruns," she said, noting that additional regulatory requirements inflated the original $660 million cost to more than $8 billion.
"To us, it doesn't appear much has changed today. Odds are that the lessons learned from Japan may very well drive costs up."
Southern Nuclear is in the final stages of its quest for a combined operating license that would authorize both the construction and operation of the new units in Burke County.
The AP1000 has been touted as the newest and safest of all reactor designs with a unique, passive cooling system that includes a reservoir of cooling water stored above the reactor.
In the event of an emergency, cooling water can flow into the system by gravity without electric or diesel powered or pumps whose tsunami-induced failure contributed to the Japan crisis.
Jim Warren of the North Carolina Waste Awareness and Reduction Network said Westinghouse also must resolve lingering issues with the AP1000 shield building design, which the NRC said could not meet impact standards associated with aircraft strikes or natural disasters, such as a tornado-propelled object.
The group also raised questions about the spent fuel storage plan, which Warren claimed was changed to higher-density storage to cut costs, despite a 2005 National Academy of Sciences warning that such "high density racking" makes the fuel storage pools more vulnerable to degradation or fire if there is even a partial loss of cooling water.
Southern Nuclear spokeswoman Beth Thomas said the company has no plans to postpone its Vogtle project.
"As it relates to the recent events in Japan, Southern Nuclear supports a safety review and incorporating lessons learned," she said. "We remain, however, fully committed to the Plant Vogtle construction project. We plan to have Unit 3 operational in 2016 and Unit 4 in 2017."