Oct 9 - McClatchy-Tribune Business News Formerly Knight Ridder/Tribune Business News - Chris Flores Daily Press, Newport News, Va.

 

Dominion Resources shut down one of its two nuclear reactors Saturday night at Surry Power Station after steam in a nearby turbine building blew sheet metal siding off the building into power lines that supply electricity to the reactors' safety systems.

The steam that was released was not radioactive and no one was injured, company officials said. Dominion is trying to figure out why steam was released about 5:18 p.m. in the turbine building, which is separate from the two large dome-shaped nuclear reactors.

Water is heated by nuclear rods inside the reactors and is transferred through pipes to the turbine building. Once they enter the building, the pipes with the heated radioactive water feed into tubes that are filled with water that never touches the radioactive water.

The nonradioactive water is heated and turns to steam, which powers a turbine and generator that send electricity to the power grid.

Somehow this steam broke through the tubes and blew off part of the side of the turbine building, which is enclosed with just sheet metal.

"It's not a large section, but the debris from the siding apparently landed on one of the overhead power lines," said Rick Zuercher, a Dominion spokesman.

There are three transformers that are backup power systems for the plant's safety systems. A second power line had also failed for a still-undetermined reason, leaving only one working outside transformer and an on-site generator.

"This caused the backup diesel generators to all start up immediately," said Zuercher.

As part of the plant's design, the reactor shuts down if it loses its power source.

But Dominion workers shut it off right before it would have anyway. Dominion declared an alert at 6 p.m. Saturday and ended the alert at 5:40 a.m. Sunday.

The alert is a formal process determined by the federal Nuclear Regulatory Commission, which must be updated on details and will investigate the incident.

When a problem occurs at a plant, there are four levels of severity, and an alert is the second lowest.

Dominion workers restored power to one of the two failed electrical systems that serve the plant by 2 a.m.

The company kept the reactor that is connected to the area of the steam problem that remained shut down while they investigated.

The reactor that was shut down was built in 1973. Richmond-based Dominion, the parent company of Virginia Power, is one of the largest operators of nuclear plants nationwide.

The utility is in the early stages of planning a new reactor next to its existing two at North Anna outside Richmond.