WASHINGTON – More than 1 million fish and crabs are sucked out of the bay each year by the Calvert Cliffs nuclear power plant, which draws about 2.5 million gallons of water per minute to cool its two nuclear reactors.
But only a fraction of those fish are killed and none are prized species, said plant officials, responding to a national report that criticized nuclear plants for killing sea turtles, seals and crocodiles, and damaging the environment by discharging large volumes of heated water.
From 1993 to 1995, more than 3.5 million fish were trapped against the screens protecting Calvert Cliffs’ 12 intake pipes, and about 280,000 died, according to estimates in the plant’s 1999 license renewal documents.
Those documents did not report crab deaths, but the Academy of Natural Sciences estimated a survival rate of 99 percent for the 5.25 million blue crabs that were trapped by the screens between 1975 and 1982.
“We’ve been studied from before the first spadeful of earth was turned,” said Karl Neddenien, spokesman for Constellation Energy Group, which owns Calvert Cliffs. “We’ve been able to demonstrate from day one that we’ve had no measurable impact on the environment.”
The report, issued last week by three nuclear watchdog groups and the Humane Society, charged that power plants avoid more environmentally friendly cooling systems, such as cooling towers, because of the costs. The groups also charged that regulatory agencies are not adequately monitoring the nuclear industries.
Linda Gunter, a study author and spokeswoman for the Safe Energy Communication Council, said it is not just an issue of what species get trapped by power plant intake systems. The death of plankton and other small species cannot be overlooked, she said.
Gunter said plankton and fingerlings, critical elements in the food chain, often pass through the screens and enter the cooling system, where they are killed.
But George Abbe, senior scientist at the Academy of Natural Sciences in St. Leonard, downplayed the impact that plant-related plankton deaths might have on the food chain. Although plankton that travels through the cooling system may be damaged or killed, he said, they can still provide food for other animals when they come out the other end.
Neddenien noted that Calvert Cliffs is not located near a sanctuary or breeding ground for protected species, as is the case for some plants in Florida and California, and the plant uses a variety of methods to minimize the loss of marine life.
Water used in the plant is returned to the bay about 10 degrees warmer than when it entered, but the plant gets most of its water from the bottom of the bay, where it is about 10 degrees cooler, Neddenien said, so there is almost no effect on the temperature of the bay.
When the plant was built, “shield walls” extending from 3 to 4 feet above the water line to within 10 to 15 feet of the bottom were constructed around the intake pipes. The wall minimizes the amount of trash and aquatic life that enters the area around the intake pipes.
The intake pipes are further protected by a trash rack, which consists of metal bars that filter out logs, trash and larger organisms, such as freshwater turtles.
Finally, traveling screens with openings about 3/8 of an inch wide, further protect the plant’s cooling system, Neddenien said. The screens are rotated and the contents, dead and alive, are washed down a waterslide back into the bay.
Jay Hixson, an Academy of Natural Sciences researcher who said he spent almost every day between 1981 and 1998 at the plant, said he remembers only turtles and horseshoe crabs being caught by the trash racks.
Richard McLean, manager of nuclear programs at the state’s Power Plant Research program, said “there’s no question that Calvert Cliffs is a predator” in the bay. But he compared the fish kills caused by the plant to losses caused by a run of bluefish.
“I’m very comfortable,” McLean said. “Calvert Cliffs does not provide an environmental impact that’s unacceptable.”
Abbe said the plant has had no effect on the crab population in the area, and the oysters grew slightly faster in the slightly warmer around the plant, which extends the growing season.
McLean and Neddenien both said most of the fish killed by the cooling system, menhaden and anchovy, were forage fish and not commercially valuable in the bay.
The state estimates the average value of fish killed between 1993 and 1995 at $5,700 per year.