Tennessee Nuclear Plant Gets Four New Steam Generators

By Dave Flessner, Chattanooga Times/Free Press, Tenn.

Nov. 1–Workers at the Watts Bar Nuclear Plant will begin unloading four new steam generators today as part of a $215 million repair of TVA’s newest reactor.

The 380-ton steam generators, built for Westinghouse Electric Co. in South Korea, arrived by barge at the Spring City, Tenn., plant Sunday night. The Tennessee Valley Authority plans to install the replacement units at Watts Bar next September, only a decade after the plant began generating power.

The existing steam generators, designed in the 1970s, have developed cracks and leaks in 6 percent of the thousands of tubes within the units, according to Paul Trudel, a project manager for TVA’s steam generator replacement program.

“This is an industrywide problem with pressurized water reactors like Watts Bar that we have closely monitored for years,” he said. “We determined that the refueling outage in 2006 would be the best time to make these replacements.”

The leaky tubes within the steam generators have been plugged by TVA and don’t present any danger to plant employees or the public, TVA spokesman John Moulton said. But the plugged tubes do limit the efficiency of the steam generators, which convert the heat from the reactor core into steam to drive the turbines at Watts Bar.

Watts Bar Unit 1 will be one of about 40 U.S. reactors that have replaced older-version steam generators with new units. The new equipment for Watts Bar — designed by engineers at Westinghouse facilities in Chattanooga — is made of more durable nickel chromium alloys, Mr. Moulton said.

The repairs at Watts Bar will be the biggest since the reactor began generating power in 1996. TVA made a similar replacement of steam generators at its Sequoyah Unit 1 reactor near Soddy-Daisy in 2003 at a cost of more than $150 million.

“The Sequoyah project was quite successful as demonstrated by the performance of the unit since the repairs were completed,” Mr. Trudel said.

TVA is still studying if and when it may replace the steam generators at Sequoyah Unit 2. TVA’s other nuclear plant at Browns Ferrry in Alabama is a boiling water reactor and does not use such steam generators.

In 1986, TVA and other utilities settled claims against Westinghouse over the steam generator problems and obtained an extended warrantty on the equipment through 1994. But Wattts Bar, the last U.S. commercial reactor to begin power generation, took 24 years to build and get licensed and didn’t begin operation until 1996.

To remove the old steam generators and install the replacement units at Watts Bar, TVA will shut down the reactor, empty its fuel and cut a hole in the reactor building. One of the world’s largest cranes will be used to remove the old steam generators and install the new 380-ton units.

TVA will then reseal the lid of the reactor building, officials said.

TVA is building a reinforced concrete building at Watts Bar to store the old radioactive steam generators until the plant is eventually decommissioned, Mr. Trudel said.

Once the reactor is idled for refueling next fall, TVA expects to complete the replacement of the steam generators in about 80 days.

Bechtel Power Corp., which helped in the replacement of the steam generators at Sequoyah two years ago, will also help provide most of the 600 workers involved in the Watt Bar steam generator replacement next year, Mr. Trudel said.

So far, Mr. Trudel said, the project is on schedule and on budget. In fact, the four steam generators arrived on the exact date TVA prediced after the units were built in Korea, shipped across the Pacific Ocean and through the Panama Canal and up the Tennessee-Tombigbee Waterway and the Tennessee River to Watts Bar.

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