Womack: Grand Gulf at little risk from earthquakes
Published: March 17,2011
PORT GIBSON — Mississippi has one nuclear power plant, Grand Gulf at Port Gibson, about 200 miles from the Gulf Coast. And that plant has only one reactor.
Within a year, it will be the largest single nuclear reactor in the United States. And it sits in the fringe area of a quake zone for the New Madrid fault, the most active fault in the central United States.
Mississippi Emergency Management Agency executive director Mike Womack said there’s very little risk of Grand Gulf being damaged by an earthquake.
The question has come up, in light of the earthquake in Japan that crippled a six-reactor nuclear plant at Fukushima. Fukushima and Grand Gulf both have boiling water-type reactors.
Womack said, “The farther you get from Memphis the less damage we anticipate from a large earthquake that would affect northern Mississippi.”
He said the New Madrid fault line just barely extends into Mississippi.
The New Madrid fault zone includes Mississippi, Missouri, Alabama, Arkansas, Illinois, Indiana, Kentucky and Tennessee. The New Madrid Fault, a network of deep cracks in the earth’s surface from southern Illinois to northeastern Arkansas and into northwestern Mississippi, produces hundreds of small quakes a year, most too weak to be noticed without scientific equipment.
Womack said a national quake response exercise to be held in May involves 10 states, but the exercise doesn’t include the county where Grand Gulf is located.
What the scientists estimate, he said, would be noticeable shaking in South Mississippi and damage would be light — pictures shaking on a desk, pictures falling off a wall, but nothing that would affect a nuclear power plant.
The chart he had was developed by the Mid-America Earthquake Center at the University of Illinois and Virginia Tech.
Grand Gulf is at the lower end of what they consider to be moderate damage, Womack said, cracks in plaster and masonry, small slides along creek banks and cracks in concrete ditches.
“None of this should impact our nuclear facilities,” he said. “They were built much stronger. They’re more concerned about 150 mph hurricane-force winds.”
There are two nuclear reactors closer to the Mississippi Coast than Grand Gulf. Entergy is the majority owner of all three. One is the Waterford plant southwest of New Orleans. It is less than 100 miles from Gulfport. And the other is the River Bend plant, on the Mississippi River about halfway between New Orleans and Port Gibson. It’s is about 125 miles from the coast. All three were built about the same time and are about 25 years old.
“As you go further down to the Louisiana plants,” Womack said, “they fall under a light category — dishes broken, pictures off the wall, furniture overturned and cracks in masonry.”
Grand Gulf is undergoing a $510 million upgrade that will enable it to produce 1,443 megawatts of power at its peak, surpassing the output of any other single reactor in the United States. And at 25 years of age, it is not considered old.
Mike Bowling, communications director for Entergy’s nuclear fleet, said there hasn’t been nuclear-plant construction in the United States in at least two decades, until now. It is expected that four to six new units may come on line by 2018.
Southern District Public Service Commissioner Leonard Bentz said he’s worried that the incident in Japan will undermine public opinion and erase years of good will.
“The U.S. was finally grasping the nuclear move to electricity,” he said. “I’m nervous that (Three Mile Island) is going to come back into the equation and put nuclear power back on the back burner.
“It’s the most efficient and best way to produce energy,” he said.
Bowling said the Nuclear Regulatory Commission requires plants be built with the most severe historically recorded natural disasters for the area in mind.
Grand Gulf is 280 miles from the New Madrid fault, yet its potential quakes were taken into consideration when the plant was built, he said.
The 1811 and 1812 quakes made the Mississippi River run backward north of Memphis and in northwest Tennessee. The quakes were felt for 1,200 miles in any direction, throughout Louisiana, even in New Orleans.
Gary Patterson, with the Center for Earthquake Research and Information at the University of Memphis, said that in an instant a 15-foot wall of earth shot up along a line that ran for 40 miles. It cut through the path of the Mississippi River in more than one place, raising the downstream side of the river, like tilting a playing field.
“It’s documented in the surface geology of the area,” he said.
That happened in northwest Tennessee and Missouri.
The southwest arm of the quake zone is close to Memphis and that’s where the closest danger would be for Mississippi.
Source: The Associated Press
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