Design flaw at new nuke?

The nuclear reactors Southern Co. is building near Augusta could be more dangerous in an accident than older reactors, a nuclear expert working with environmental groups warned on Wednesday.

The new AP 1000 reactors, designed by Westinghouse, lack a backup system for containing radiation if its initial protective layer develops holes, said Arnie Gundersen of Vermont-based Fairewinds Associates. Gundersen has testified nationally on nuclear issues.

Older reactors have two layers of containment, with concrete barriers backing up vessels made of steel, he said. The AP 1000 will not have this. The steel containment vessel sits inside a concrete structure with an unfiltered vent at the top.

If radiation escaped the reactor into the steel container, and the container had an undetected hole, the radiation would release into the atmosphere, Gundersen said. A number of operating reactors have had steel containment corrosion problems. He said a filter should be added at the top of vent at additional cost.

Westinghouse spokesman Scott Shaw said the company is looking at Gundersen’s analysis. He also said Gundersen’s radiation leakage scenario is highly unlikely, noting the steel containment vessel in the new reactors will be far thicker than those in older reactors, built at 1-3/4-inch thick.

Ongoing inspection programs would identify containment system holes before the holes caused problems. "If a hole develops, we'll find it," Shaw said.

Gundersen explained his concerns in a telephone briefing sponsored by the AP 1000 Oversight Group, a coalition of environmental organizations in the South. They include the Southern Alliance for Clean Energy and Georgia WAND. The group wants the the Nuclear Regulatory Commission to look at the AP 1000 containment system.

Fourteen AP 1000 reactors are planned in the Southeast. Two reactors at Georgia Power's Plant Vogtle likely will be the first.  The company has been offered $8 billion in loan guarantees for the project and has until next month to accept.

The AP 1000 design is now on its 18th revision at the NRC. The company is currently working with the agency to allay concerns about security of its shield building.