Three of five members of the Nuclear Regulatory Commission voted this week to approve a new and revised advanced reactor design that could lead to the first plants being built in the United States in more than three decades.

NRC Chairman Gregory Jaczko and the two Democratic commissioners said they voted to approve Westinghouse Electric Co.'s AP1000 nuclear plant model that they say is safer and simpler than existing plants. The reactor design could be used in up to 12 proposed U.S. reactors, starting with Georgia and South Carolina.

"The combination of passive safety, severe accident, and defense-in-depth features gives me confidence that the AP1000 design is sufficiently safe," Jaczko said in the ballot he cast on Dec. 6 and announced this week.

The agreement of the chairman and two commissioners is a departure from the nasty feud between Jaczko and the four other commissioners. In Capitol Hill hearings this week, his colleagues have accused Jaczko of berating female staffers, withholding information from his colleagues and abusing his authority during emergencies -- allegations the chairman denies (E&E Daily, Dec. 15).

The infighting did not keep Jaczko from joining Commissioners William Magwood and George Apostolakis in approving a new advanced reactor design from Westinghouse, a subsidiary of Toshiba Corp. The company, they said, has shown the structure is sound and sufficiently addressed concerns about the plant's ability to withstand earthquakes and temperature shifts, they said (Greenwire, May 27).

The commission's two Republican commissioners, Kristine Svinicki and William Ostendorff, have not yet revealed how they will vote.

The votes won't be finalized until the agency meets Dec. 22 on the final certification rule, NRC spokesman Scott Burnell said.

The three NRC members who voted for the design applauded its simplicity and ability to maintain core cooling for at least 72 hours with little human intervention. During that time, plant operators could repair a plant damaged by natural disasters or other events and transport emergency equipment or fuel needed to continue cooling the reactors.

The silo-shaped design includes fewer electric pumps, valves, piping and other gadgets that could be knocked out during a natural disaster or terrorist attack, Westinghouse says. Instead, the AP1000 includes massive water storage tanks at the top of the structure that would open during an emergency and release water to cool the steel containment vessel that houses the reactors. At that point, gravity and convection would cool the plant until operators can safely shut it down, said Scott Shaw, a spokesman for Westinghouse.

Jaczko, Magwood and Apostolakis also rebuffed concerns of nuclear skeptics who question the reactor's ability to withstand extreme events like the earthquake and tsunami that struck Japan's Fukushima Daiichi nuclear complex in March. The design was first approved in 2006 but Westinghouse asked a year later to amend the model to address questions about the shield building and peak accident pressures expected within the reactor's containment.

Magwood said the AP1000's reliance on a passive safety system would have prevented similar problems. Jaczko agreed, saying the Westinghouse design meets the safety requirements of NRC's internal task force that reviewed the Japanese disaster.

NRC staff also addressed concerns that fell outside the agency's safety review, including whether the steel containment shell would rust as it did at FirstEnergy Nuclear Operating Corp.'s Beaver Valley plant in Ohio, Magwood said. "I find that the design of the AP1000, which provides for a three foot air gap between the liner and the shield building, precludes the chain of events that led to the Beaver Valley corrosion," Magwood said.

If NRC approves the AP1000 design, the agency may decide within months to approve construction and operating licenses for plants in South Carolina and Georgia that would use the model, Shaw said.

Southern Co. hopes to receive two combined licenses to build and operate the $14 billion Vogtle Units 3 and 4 near Waynesboro, Ga., and South Carolina Electric & Gas Co. wants to use the design in two proposed reactors at its V.C. Summer station northwest of Columbia, S.C.

If approved, the licenses would be the first for new reactor construction since 1978 (Greenwire, Sept. 28).

Four plants that use the new AP1000 design are currently under construction in China with the first coming online in 2013, Shaw said. Overall, there are about 440 operating reactors using other AP1000 designs around the world, he said.

Click here for Magwood's vote.

Click here for Jaczko's vote.

Click here for Apostolakis' vote.