Critics Call Vt. Yankee Repairs Sign of Plant’s Age
06/26/12 7:34AM By John Dillon
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The Vermont Yankee nuclear plant continues to operate at reduced power as technicians test repairs to a pump system that controls the reactor's output.
The system suffered an electrical failure a week ago. Critics say the break-down is a sign the 40 year-old reactor is showing its age. Entergy, Yankee's owner, says the plant has been well maintained.
Yankee spokesman Rob Williams says the motor that failed controls pumps that send cooling water to the reactor.
"The motor generator sets, and there's two of them, are used to vary reactor power by varying the flow of reactor cooling," he says. "So they're sort of like a throttle for reactor power."
With one of the two motors disabled, Yankee throttled back to 45 percent power last week. It was unfortunate timing for Entergy because high temperatures throughout the region had boosted demand - and prices - for wholesale electricity.
Williams says technicians have repaired wiring in the motor generator. But he could not predict when the plant will be operating at full power.
"The motor work has been completed and it's been remounted back in place," he says. "And we're doing testing. Following that testing, it will be actually re-connected and made ready for putting back in service."
The motor failed due to an electrical short that released smoke into the reactor building. Arnie Gundersen, a nuclear engineer and member of a state Yankee oversight panel, says equipment breakdowns like this should not be a surprise.
"This issue of aging wiring is a reliability concern that the panel had for years. And anybody who's had a 40 year old car knows that the insulation on wiring gradually breaks down because it's made of plastic and plastic doesn't last for years," he says.
Gundersen says Yankee has experienced several problems this year - from a leaking condenser to the failed pump.
"Since the 40th birthday the plant has been repeatedly down to less than 50 percent power with condenser problems. And now of course for last week it's been down to less than 50 percent with this pump problem," he says.
But plant spokesman Williams says Entergy has constantly replaced and updated reactor components.
"Vermont Yankee has been a highly reliable plant and that certainly continues under the Entergy ownership," he says.
Williams says Yankee continues to investigate the cause of the electrical failure.