Utility says no risk in stored fuel mishap

Mar 29 - McClatchy-Tribune Regional News - Rusty Dennen The Free Lance-Star, Fredericksburg, Va.

Spent nuclear fuel was improperly loaded into storage containers at Dominion power's North Anna and Surry power plants, but company officials say the public was not at risk.

Seven storage casks at North Anna Power Station and four at Surry Power Station were affected, said Richard Zuercher, a spokesman for Dominion's nuclear operations.

The North Anna plant is on Lake Anna, near Mineral in Louisa County. Surry is on the James River near Williamsburg.

"We do not believe it poses any safety issue," Zuercher said yesterday.

The loading error was discovered in a review of storage documents and reported by Dominion to the Nuclear Regulatory Commission on Thursday.

Zuercher said the positions of some fuel assemblies were inadvertently switched in the casks. Fuel assemblies with a higher residual heat were supposed to be stored on the bottom of the casks. But it was discovered that in the 11 casks, assemblies with higher heat -- exceeding 800 watts -- were stored on top.

"The idea is that air circulates from the bottom up to the top. The fuel is pretty old -- from the early days of operation. My sense is that it did not exceed 800 watts by much," Zuercher said.

He said the casks exceeded the limit when they were first loaded years ago, but all but one cask at North Anna are now within the NRC limits.

"There's plenty of margin on those cannisters, but we realized we had loaded them incorrectly and we wanted to inform the NRC," Zuercher said.

The fuel assemblies begin as a bundle of zirconium tubes filled with pelletized uranium oxide. Every 18 months, new fuel assemblies are loaded into the reactors. The highly radioactive used ones are cooled in large underground containers, resembling swimming pools, for five to seven years.

At that point, the spent fuel is cool enough to be sealed in the steel casks, which sit on platforms in a secure area of the plants near the reactors.

North Anna has 37 casks. Twenty-seven are the older vertical storage casks; 10 are the newer nuclear horizontal modular storage design. Each cask holds 32 fuel assemblies. Surry has 69 storage casks.

Spent fuel is stored on site at nuclear power plants across the nation -- either in pools or casks -- as discussions continue over options for a permanent storage solution.

Rusty Dennen: 540/374-5431

Email: rdennen@freelancestar.com