Climate vulnerability -- TVA reactor shut down; cooling water from river too hot

Houston Chronicle, via AP: The Tennessee Valley Authority shut down one of three units at the Browns Ferry nuclear plant Thursday because water drawn from a river to cool the reactor was too hot, a spokesman said.

The nation's largest public utility shut down Unit 2 about 5:42 p.m. CDT because water drawn from the Tennessee River was exceeding a 90-degree average over 24 hours, amid a blistering heat wave across the Southeast.

"We don't believe we've ever shut down a nuclear unit because of river temperature," said John Moulton, spokesman for the Knoxville, Tenn.-based utility.

He said TVA would compensate for the loss of power by buying power elsewhere. The utility announced earlier Thursday that it was imposing a fuel surcharge on customers because of lower hydroelectric power production caused by drought conditions.

Two other units at the plant were operating, as well as towers to cool the water. But searing temperatures and a lack of cooler water in the upper part of the Tennessee River system made it too difficult to provide cool water for all three reactors. There was no safety threat posed by the shutdown.

Moulton said the average high temperature Thursday was 103 for five of the largest cities in TVA's coverage area: Huntsville and Knoxville, Chattanooga, Memphis and Nashville in Tennessee. "It's the hottest in 20 years," he said. He would not estimate when the unit would go back on line, saying it will depend on the weather.

"Temperatures are supposed to moderate some, but it will take a while for the river temperature to do that, too," Moulton said….