Browns Ferry cuts output; river too warm: 1 reactor taken offline, 2 slowed down

Aug 17 - McClatchy-Tribune Regional News - Eric Fleischauer The Decatur Daily, Ala.

The same heat that is triggering historic energy demand in the Tennessee Valley forced TVA to cut power production at Browns Ferry Nuclear Power Plant.

At about 5 p.m. Thursday, TVA officials decided to manually shut down Unit 2 to reduce the temperature of water discharged from the plant, Browns Ferry spokesman Jason Huffine said.

Units 1 and 3 continued operating at about 70 percent power, Huffine said.

Browns Ferry sucks water from the Tennessee River into the plant, circulates it to reduce heat in the plant, cools it to 90 degrees or below in the cooling towers and discharges it into the river.

Federal regulations prohibit the plant from discharging water that exceeds 90 degrees into the Tennessee River. High temperatures of the river water taken into the plant, however, have increased the temperature of the discharged water, Huffine said.

To keep the discharge water temperature at or below 90 degrees, TVA had to reduce power production.

"The last 24-hour average I saw was right at 90 degrees. That's why we took it off," Huffine said of water temperatures taken downstream of the plant.

The 24-hour average upstream was 90.4 degrees, he said.

"These temperatures are just record-setting, and we're having to take what Mother Nature is dishing out. We've never reached this 90-degree threshold," Huffine said.

"To our knowledge, this has never been an issue," he said. "We haven't dropped a unit for this before."

TVA had reduced output on Units 1 and 3 by 15 percent earlier Thursday.

Unit 2 had been running at 73 percent before shutdown. It was already at reduced power because TVA is repairing a pump.

"This pump takes the water from the river," Huffine said. "It has to do with the condensers. The condensers turn the steam back into water before it goes back to the river."

Huffine said the pump malfunction does not raise safety issues for the public.

Unit 2 won't return to power until maintenance is complete, he said.

"Right now we don't really have a set schedule when we're going to put that unit back online. When we drop a unit, we don't put it back online until we've looked at everything," he said.

The shutdown shouldn't affect TVA's ability to meet the high demand for power, Huffine said.

TVA broke records for peak demand last week. High temperatures Thursday made it likely it would break the record again.

"The TVA system is pretty robust and we feel confident we'll be able to continue to meet those demands," Huffine said.