Vermont Yankee to power down to fix leak

Tuesday, June 9, 2009

By BOB AUDETTE, Reformer Staff
Brattleboro (VT) Reformer

BRATTLEBORO -- The miles and miles of pipes that are used to cool reactor steam produced by Vermont Yankee nuclear power plant sprang another leak Monday. According to a press release from Yankee, the plant will be reducing power in "the next several weeks" to attempt to repair the condenser, stated Rob Williams, spokesman for Yankee, in a press release detailing the leak.

The condenser acts as a radiator, using water from the Connecticut River to cool steam from the reactor, turning it back into water before sending it back to the reactor. The condenser is overpressurized to prevent reactor water from getting into the river.

The leak is allowing river water to enter the system and was discovered after plant technicians identified a slight increase in the chloride concentration in the reactor water.

"This condition has occurred at Vermont Yankee several times over the life of the plant including the last operating cycle," stated Williams. "Planning is under way to temporarily reduce power to allow technicians to identify the precise location of the leak and to repair it."

In April 2008, a similar 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 is made up of 24,000 copper-alloy tubes containing cold riverwater, which removes the heat from the steam. A total of 360,000 gallons per minute of river water flows through the condenser tubes during normal plant operation.

The leak is allowing one-half gallon a minute of river water into the reactor water system. Filters are installed in the system to remove any contaminants in the river water from getting into the reactor.

"Vermont Yankee has been aware of its condenser problems and has made the economic decision to wait until license renewal is approved to repair or replace it," said Arnie Gundersen, a critic of the manner in which Entergy, which owns and operates Yankee, maintains the plant.

Condenser replacement or retubing is currently scheduled for the refueling outages in 2013 and 2014, said Gundersen. It could take up to $100 million to "fix it right," he said.

Gundersen was a member of the Public Oversight Panel, which reviewed an audit of the power plant that was mandated by the Vermont state Legislature. Entergy has applied to the Nuclear Regulatory Commission to extend the operating license to 2032. It also must receive approval from the Vermont Department of Public Service and the state Legislature.

The Legislature asked for the audit to help it inform its decision on whether to allow the plant to continue operating. The Legislature is expected to render a decision during its 2010 legislative session.

Gundersen identified the condenser problems during power uprate hearings in 2003.

According to the audit, the condenser is near the end of its useful life and might not be able to operate reliably through 2012 without some remedial actions. "Vermont Yankee has known about (the problem) since 1999," said Gundersen, three years before it bought the plant from the Vermont Yankee Nuclear Power Corp. Leaks are caused by thinning tubes, according to Gundersen.

Fair Use Notice.