Second leak in two weeks found at VY
Last week, technicians discovered a leak in the plant's condenser tubes, miles of piping used to cool down radioactive steam produced by the reactor to power the plant's turbine.
The service water leak is located near the plant's intake structure on the Connecticut River, according to the NRC. The section of piping of concern channels water that is sprayed on screens used to minimize the buildup of debris on those screens. The screens themselves keep debris from the river from entering the plant's condenser tubes.
A Yankee spokesman said the valve to the service water pipe has been shut off, meaning it is not actively leaking at this point. It will only be turned on when enough debris -- such as sticks, stones and mud -- has accumulated on the screens to justify a backwash to flush them clean, said Larry Smith, Yankee's director of communications.
The pipe is an eight-inch line and was found to be leaking in the past two days by technicians conducting their normal inspection rounds, he said.
Shutting off the valve is "obviously a temporary solution," wrote Neil Sheehan, spokesman for the NRC, in an e-mail to the Reformer.
Vermont Yankee technicians will need to develop a plan to make permanent repairs to the piping, he wrote. They are in the process of performing an "extent-of-condition" review to check this leak and associated piping using ultrasonic testing.
The NRC's resident inspectors, who are stationed full time at the power plant, are monitoring the technicians' progress.
In the plan being prepared by Yankee, said Howard Shaffer, a nuclear engineer who assisted in start-up operations at the power plant in 1972, technicians need to explain why the leak happened.
"The leak points to a missed pipe thinning spot in the pipe measuring under the Erosion Corrosion program," he said.
He added that Yankee needs to explain how it is going about finding other pipe thinning in the plant.
The spray function itself is not safety related, stated Sheehan, since the problem does not affect the ability to safely shut down the plant. However, he wrote, the piping that supplies water for the spray function is classified by the American Society of Mechanical Engineers as safety related.
"The water taken off of that piping for spraying onto the traveling screens is not a safety function," he stated. "In other words, the plant could take water from another source to spray debris off the traveling screens."
Despite the leak, there is no danger of radioactive water leaking into the river, stated Sheehan.
"This water does not come into contact with radioactivily contaminated water in the plant."
A spokesman for a local anti-nuclear group said this leak is just another reason why Vermonters should replace Yankee with clean renewable energy sources.
"Vermont Yankee is falling apart," said Ed Anthes, of Nuclear Free Vermont by 2012. "At this rate, we'll be lucky if Entergy makes it to 2012 safely."
Entergy, which owns and operates Yankee, has applied to the NRC to extend the plant's operating license from 2012 to 2032.
Another spokesman for an anti-nuclear group said Yankee is too old to continue operation past 2012.
"At what point is this thing leaking too much?" asked Bob Stannard, a lobbyist for the anti-nuclear Citizen Action Network. "If ever there was a clearer indication that this plant is showing its age it's what's happening in front of our eyes."
In April 2008, a condenser leak forced the plant to power down to 45 percent of its 650-megawatt capacity. The leak was estimated to be about one quart a minute.
Technicians were unable to find the leak and returned the plant to 100 percent.
The condenser leak discovered last week -- of about one-half gallon a minute -- will be repaired "in the next several weeks" after the plant has reduced power for that purpose, according to a press release issued at the time of the discovery of the leak.
The condenser is made up of 24,000 copper-alloy tubes. A total of 360,000 gallons per minute of river water flows through the condenser tubes during normal plant operation.
Filters are installed in the system to remove any contaminants in the river water from getting into the reactor. The condenser is designed in a way that prevents contaminated water from entering the river.
Condenser replacement or retubing is scheduled for refueling outages in 2013 and 2014, and it could cost up to $100 million to fix.
According to a recent audit conducted at the plant, the condenser is near the end of its useful life and might not be able to operate reliably through 2012 without some remedial actions.
Entergy has indicated it is waiting to learn if it can continue operation of the plant past 2012 before it replaces the condenser.
The consultants assigned to conduct the audit were specifically asked to address the service water issue, said Arnie Gundersen, a member of the public oversight panel tasked with reviewing the audit.
"Today's leak shows a weakness in the overall audit process," said Gundersen, who has been asked to oversee Entergy's progress in addressing issues raised in the audit.
Bob Audette can be reached at email@example.com, or 802-254-2311, ext. 273.
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