Thursday, March 17, 2011

TVA debating new nuclear reactor

From today's Tennessean...

TVA to review Japan situation while debating new nuclear reactor

The TVA board has been poised to discuss whether to pay billions to build a new nuclear reactor, and now its members will have Japan's nuclear breakdown to consider when they meet next month.

"We will have a comprehensive review of what lessons are coming out of this situation in Japan and implications for TVA," said Dennis Bottorff, chairman of the board and managing general partner in a Nashville venture capital firm.

There may not be any conclusions about exactly what went wrong in Japan by the time of the April 14 meeting, but one immediate concern is that three of Tennessee Valley Authority's existing reactors are largely the same design as those affected by Friday's earthquake in Japan.

The three reactors at TVA's Browns Ferry site, which lies about 100 miles south of Nashville, are a 1970s-era General Electric boiling water design similar to the Japanese reactors. They are among 35 boiling water-type reactors in the U.S.

"We're all closely watching the events in Japan and monitoring the things happening there with an eye to learning lessons that we may incorporate into our operations," Bill McCollum, TVA's chief operating officer, said Tuesday.

"Right now there's a lot of information, some of which may turn out with time to be correct and some not correct. We've got to work through that."

TVA has two other plants that have pressurized water reactors, a different design than the damaged GE boiling water reactors in Japan. Most commercial reactors in the U.S, about 70, are pressurized water reactors,

TVA's Watts Bar plant, which is 60 miles southwest of Knoxville, has one of these reactors, and a second one is under construction there.

At TVA's Sequoyah plant, 18 miles northeast of Chattanooga, there are two such reactors.

The pressurized water reactors at these plants differ from the boiling water reactors in that the steam to run the turbine is produced in a steam generator.

Water in the GE-designed reactors at the Japanese plant and at Browns Ferry boils inside a pressure vessel, and a steam-water mixture is produced. Steam eventually goes to a turbine generator to create electricity.

McCollum said he did not know the detailed differences between the GE boiling water reactor at the Browns Ferry plant and the Japanese reactors, but he said that is being researched.

It appeared that at least one of the Japanese reactors doesn't include some of the circulating and cooling pumps found at Browns Ferry.

Pools can be problem

Another issue in Japan is possible problems with the used fuel pools, where highly radioactive rods of old fuel typically are left for several years. U.S. plants have such pools, too.

At TVA, the old fuel is moved out of the pools after a few years and put into dry casks for long-term storage.

"Our plants are designed, built and operated safely, and we have equipment and procedures and personnel in place to maintain the safety of our plants," McCollum said.

He said they are built to withstand slightly more than the size of an earthquake that might be expected at their particular locations. The TVA nuclear sites are all along the Tennessee River.

TVA is considering completing a new reactor at a cost of up to $4 billion at its Bellefonte site near Hollywood, Ala., which is about 110 miles southeast of Nashville.

Construction began on the plant in the 1970s and halted in the 1980s.

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