Vermont Yankee Forced to Reduce Power

Associated Press: DAVID GRAM, August 22, 2007

MONTPELIER, Vt. - The Vermont Yankee nuclear plant was forced to reduce its power output by at least half on Tuesday after staff at the Vernon reactor detected problems with one of its two cooling towers.

Neil Sheehan, a spokesman for the federal Nuclear Regulatory Commission's regional office for the Northeast, said the problems did not raise a safety concern at the plant.

But he said if allowed to fester, they likely would cause the plant to violate its state water discharge permit by spilling more heated water back into the Connecticut River (otcbb: CRCA.OB - news - people ).

The problem "does not affect the safe operation of the plant," Sheehan said Tuesday. "They're really just there to comply with the state discharge limits."

Both wooden components and piping had failed in one of the towers, said Sheehan and Robert Williams, spokesman for plant owner Entergy (nyse: ETR - news - people ) Nuclear.

Sheehan said the plant had reduced power by 60 percent of its usual, 610-megawatt output, and that repairs "will take several days, at least." The summer power reduction comes during a time of year when demand is relatively heavy on the New England power grid.

Williams said the plant's power reduction target actually was 50 percent, but it would reduce power below that level temporarily.

Vermont Yankee's cooling towers are not of the iconic bell-shape recalled from the Three Mile Island nuclear plant or seen on the hit TV series "The Simpsons." Rather, they are two rectangular-shaped banks of 11 cooling towers apiece, each bank 50 feet high, 40 feet wide and 300 feet long, Sheehan said.

River water is taken into the plant to cool various components. In winter, it is sent directly back to the river. In summer, some is sent to the cooling towers, where it is allowed to fall through the tower much like rain, cooled by fans pulling air into the tower from the outside.

The cooling towers became embroiled in controversy two years ago, as Vermont Yankee was seeking approval - eventually received - to increase its power output by 20 percent.

The plant also won approval to increase water temperatures in the river near the plant by 1 degree above previously set limits, arguing that failing to get that permission would cause it to have to use its cooling power more, driving up costs.

Arnie Gundersen of Burlington, a former nuclear industry engineer and now an industry critic, said he was not surprised the plant was experiencing problems in the cooling towers. He said the type of towers used at Vermont Yankee had been prone to collapse at other power plants and refineries where they are used.

He said the plant's 20 percent power boost left it needing to use more cooling water, creating "additional rain and additional weight on the towers." Before the plant increased its power output from 540 to 610 megawatts, the problems seen Tuesday "probably wouldn't have happened," Gundersen said.

Sheehan said the problem began to come to light late last week when plant technicians heard rubbing that he said originated with a fan in one of the cooling towers. When they inspected the noise, they found some "degradation" in some of the wood that makes up most of the structure of the towers.

The NRC spokesman said the problem was "sagging" in parts of the wooden structure. "I don't know if I'd characterize it as rotting, but more sagging, deformation in some of the wood," he said of the material that was installed before the plant opened in 1972.

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