Drought could shut down nuclear power plants

At a nuclear plant, water is also used to cool the reactor core and to create the steam that drives the electricity-generating turbines. But those are comparatively small amounts of water, circulating in what are known as closed systems — that is, the water is constantly reused. Water for those two purposes is not threatened by the drought.

Instead, the drought could choke off the billions of gallons of water that pass through the region’s reactors every day to cool used steam. Water sucked from lakes and rivers passes through pipes, which act as a condenser, turning the steam back into water. The outside water never comes into direct contact with the steam or any nuclear material.

At some plants — those with tall, Three Mile Island-style cooling towers — a lot of the water travels up the tower and is lost to evaporation. At other plants, almost all of the water is returned to the lake or river, though significantly hotter because of the heat absorbed from the steam.

Progress spokeswoman Julie Hahn said the Harris reactor, for example, sucks up 33 million gallons a day, with 17 million gallons lost to evaporation via its big cooling towers. Duke’s McGuire plant draws in more than 1 billion gallons a day, but most of it is pumped back to its source.

Nuclear plants are subject to restrictions on the temperature of the discharged coolant, because hot water can kill fish or plants or otherwise disrupt the environment. Those restrictions, coupled with the drought, led to the one-day shutdown Aug. 16 of a TVA reactor at Browns Ferry in Alabama.

The water was low on the Tennessee River and had become warmer than usual under the hot sun. By the time it had been pumped through the Browns Ferry plant, it had become hotter still — too hot to release back into the river, according to the TVA. So the utility shut down a reactor.

David Lochbaum, nuclear project safety director for the Union of Concerned Scientists, warned that nuclear plants are not designed to take the wear and tear of repeatedly stopping and restarting.

“Nuclear plants are best when they flatline — when they stay up and running or shut down for long periods to refuel,” Lochbaum said. “It wears out piping, valves, motors.”

Both the industry and NRC spokesman Scott Burnell said plants can shut down and restart without problems.

More from msnbc.com Red Tape: Now’s your chance to spy on Google Fact or fiction? ‘McCain’ Dems opposed health bill Kenyan girls given a chance to dream On Twitter: Breaking news updates | Weird and wild

MORE FROM WEATHER

Weather Section Front

Weakening Ida drenches Gulf Coast   Dad, 7 kids survive car being buried in snow   Watch 3-day national forecast 10,000 Salvador flood victims need food Landslide kills at least 42 in India   Tornado rakes Oregon coastal town Weather Section Front   Add Weather headlines to your news reader: