A coalition of public-interest groups filed a legal challenge today with the U.S. Nuclear Regulatory Commission seeking to halt the fast-track approval process for the Westinghouse AP1000 reactor that utilities are planning to build across the South.

Filed directly with the NRC's five commissioners rather than agency staff, the petition [pdf] calls for suspension of the design approval process to consider safety concerns raised by experts -- and to allow time for the lessons of the Japanese nuclear disaster to be absorbed.

"There is no cause to rush the design certification for the AP1000," says John Runkle, attorney for the AP1000 Oversight Group. "Well before the emergency in Japan, serious shortcomings with the Westinghouse model had been identified. The events at Fukushima redouble the need for a careful and transparent review of the AP1000 relating to both safety and cost."

The motion notes that the NRC spent a year and a half after the 1979 Three Mile Island accident studying the disaster's implications. That effort led to regulatory changes making both existing and proposed reactors safer.

The Westinghouse AP1000 is the design chosen for construction of 14 reactors at seven sites across the Southeast. The companies seeking to build those reactors are Duke Energy, Florida Power & Light, Progress Energy, SCANA, Southern Company and TVA. Westinghouse is majority-owned by Japan's Toshiba Corp. Last year the Obama administration awarded the project at Southern Company's Plant Vogtle in Georgia an $8.2 billion federal loan guarantee.

The AP1000 Oversight Group charges that industry pressure caused NRC to skip testing of key aspects of the AP1000 design. Dr. John Ma, the NRC's lead structural engineer charged with evaluating the reactor's shield building, filed a formal nonconcurrence against approval of the design last November. He cited concerns that the new concrete material being used in the building is so brittle it could shatter "like a glass cup."

Other problems the coalition points to include high storage density in the spent fuel pools and a weak containment structure. In addition, NRC science advisers have warned that potential clogging in the reactor's passive emergency cooling system could dramatically increase the risk of a meltdown.

The petitioners acknowledge fundamental differences between the AP1000 design and the GE-Hitachi boiling water reactors used at Fukushima and many sites across the United States. However, they also point out that the Fukushima accident has direct implications for the AP1000 design and operation.

"Accidents with catastrophic consequences that were once considered to be of extremely low probability have occurred," the motion states. "Now the ramifications of those accidents must be dealt with and resolved safely before new designs are reviewed and certified, and new reactors are licensed."

In February, the NRC announced its preliminary approval of the AP1000 design. It required public comments to be filed in 75 days,and for the NRC staff to finalize approval 30 days after that.

The members of the AP1000 Oversight Group are the Bellefonte Efficiency and Sustainability Team, Blue Ridge Environmental Defense League, Citizens Allied for Safe Energy (Miami), Friends of the Earth, Georgia Women's Action for New Directions, Green Party of Florida, Mothers Against Tennessee River Radiation, NC WARN: Waste Awareness and Reduction Network, Nuclear Information and Resource Service, Nuclear Watch South, Sierra Club's South Carolina Chapter, and the Southern Alliance for Clean Energy.