TVA nuclear reactor needs $200 million repair

SPRING CITY, Tenn. - Oct 7 (The Associated Press)

Eight years into a licensed 40-year lifetime, the $7 billion Watts Bar nuclear station needs a $200 million repair.

The Tennessee Valley Authority plans to replace four steam generators at the single-reactor plant located about 40 miles south of Knoxville. The plant began operation in 1996 after 23 years of interrupted construction.

TVA is not alone. Utilities across the nation are having to replace these expensive pieces of equipment at pressurized water reactors like Watts Bar because of leaking tubes affecting power generation.

"You reach a point where you have to make a business decision to either have less output from the plant or to replace the steam generator," said Paul Trudel, project engineer for the steam generator replacement.

The steam generators essentially are heat exchangers. Water from the reactor goes through the generator and is turned into steam, which turns turbines that produce electricity.

In 2003, TVA spent $177 million replacing steam generators on the Unit 1 reactor at Sequoyah nuclear plant near Chattanooga. The federal utility expects to receive Watts Bar's steam generators by late 2005 and install them in 2006.

David Lochbaum, nuclear safety engineer with the Union of Concerned Scientists in Washington, D.C., said the problem can be traced to the stainless steel alloy used in the steam generator tubes.

"The material ... was thought, when the plants were designed and constructed, it wouldn't degrade over 40 years," Lochbaum said. Instead, the metal proved vulnerable "to a number of degradations, corroding, cracking, swelling up."

That can lead to safety problems as well as loss of generation capacity, he said.

The steam generators are no longer made in the United States. TVA will contract with Westinghouse in Chattanooga, which designed the system and will buy and ship the steam generators from Doosan in South Korea.

The old steam generators, having received water from the reactor, are highly radioactive and must be carefully stored. The ones at Sequoyah are encased in a concrete-reinforced bunker and stored at the plant site. TVA plans to store the steam generators at Watts Bar the same way.

TVA is the nation's largest public utility serving 8.5 million people through 158 distributors in Tennessee and parts of Alabama, Kentucky, Georgia, Mississippi, North Carolina and Virginia.

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TVA: http://www.tva.com

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Information from: The Knoxville News Sentinel, http://www.knoxnews.com