Va. quake shifted spent nuclear fuel containers

Last week's central Virginia earthquake jolted huge concrete containers holding spent nuclear fuel at the North Anna power plant in Louisa County, shifting some one to four inches, said the plant's operator, Dominion Virginia Power.

The containers, called casks, weigh 115 tons each and are filled with bundles of uranium dioxide fuel rods that no longer generate enough heat to produce electricity.

The plant houses a total of 53 casks on two concrete pads. Of 27 casks on one pad, 25 shifted during the magnitude 5.8 earthquake that struck Aug. 23 some 12 miles south of the plant, said Dominion spokesman Richard Zuercher.

"They are safe and remain intact," Zuercher said. "They are designed not to fall over and they didn't fall over."

Sensors designed to detect leaks of helium gas - which fill the casks - indicated no leaks, Zuercher added.

The casks - which look like concrete silos - sit on two secure pads outside the two-reactor power plant, which continues to be shut down pending inspections by a special team sent by the Nuclear Regulatory Commission this week.

Each of the 27 casks on one pad is at capacity, holding 32 fuel rods.

On a second storage pad, 26 newer storage casks did not shift, Zuercher said. Some concrete did flake off the outside of these newer casks, which sit horizontally instead of vertically like the older casks. Thirteen of those casks hold fuel; the rest are empty.

The containers that moved were licensed and began taking fuel in 1998.

"This indicates that reactors that have these dry casks in these earthquake prone areas, they're going to have to do more to protect them from ground motion," said Robert Alvarez from the Institute for Policy Studies, who has extensively studied nuclear waste storage. "One thing is to bolt them to the pads. And that's not a Home Depot-type job. The pads themselves also need to be examined to see if they're durable enough."

Zuercher said Dominion continues its own inspections of the facility alongside the NRC team. "We have not found anything significant, nothing that affects nuclear safety," he said. "Both units are offline and in cold shutdown."

On Aug. 26, Dominion notified the NRC that the earthquake may have shaken the facility more than it was designed to handle. An analysis of "shake plates" that record ground motion will be completed Friday, Zuercher said, and the company will then make a final determination if the ground motion exceeded the plant's design.

As at many U.S. nuclear plants, when fuel rods at North Anna lose power, they are moved to an indoor spent fuel pool. After cooling there for several years, workers move the rods to the so-called dry storage casks, which are outdoor and cooled by natural air circulation.

Fuel rods remain radioactive for thousands of years as they slowly decay.

Dry casks were designed as temporary storage, Alvarez said, but have become de facto long-term waste warehouses as the country has failed to build a permanent waste repository.

According to the NRC, 55 sites in the U.S. have nuclear waste in dry cask storage, including two sites in Virginia and one in Maryland, at the Calvert Cliffs facility in Lusby.

Starting in 1986, the federal government began planning to move the nation's nuclear waste to a permanent repository at Yucca Mountain in Nevada. But after President Obama took office in 2009, he defunded the partially built hole in the mountain and declared the project closed.

Lawsuits arguing for and against completing Yucca Mountain are now wending their way through federal courts.

A report released in April by the Government Accountability Office estimated that $15 billion has been spent on the attempt to find, and build, a place to put spent nuclear fuel.

Until such a site is built, waste will continue to accumulate at the nation's 104 nuclear reactors.