Can it happen here?

BY DENNIS GEISINGER

On July 19, an earthquake with a magnitude of between 6.6 and 6.8, centered near the city of Kashiwazaki, Japan, started a fire at the world's most powerful nuclear power plant, causing a reactor to spill radioactive water into the sea. According to the New York Times, the Tokyo Electric Company,which owns and operates the nuclear power plant, admitted later that "the force of the shaking caused by the earthquake had exceeded the design limits of the reactors, suggesting that the plant's builders had underestimated the strength of possible earthquakes in the region."

On April 18 last year, CNN reported on a Canadian-led study that had identified a possible driving mechanism for the "intraplate seismicity" of the so-called "New Madrid fault" running along the course of the Mississippi River Valley that had caused at least three earthquakes estimated at a magnitude of 8 or more during the winter of 1811-1812. The last and greatest of these destroyed half the town of Madrid, Mo., and sent aftershocks felt over some 1 million square miles, as far north as the Montreal region of Canada.

According to witnesses, the Mississippi River flowed backward.
According to the St. Louis University Earthquake Center, there have been at least 15 earthquakes with a magnitude of 3.0 or above throughout the area of the New Madrid Fault during the past three years.

When Southside Pride asked Viktoria Mitlyng, senior public affairs officer for the U.S. Nuclear Regulatory Commission's (NRC) Midwest office in Lisle, Ill., if the reactors at Minnesota's Prairie Island and Monticello plants could withstand an earthquake equal to the Kashiwazaki quake, she said, "Yes. Otherwise, if there was any question about safety they wouldn't be allowed to operate."

"Their entire mode of operation is based on the idea that events like that will not occur," said George Crocker, executive director of the North American Water Office in Lake Elmo. "The reality is that, by rights, it could easily already have happened at any one of the plants, world- wide," he said.

There are 438 nuclear reactors in operation worldwide, according to the European Nuclear Society. Here in America, the federal NRC and the Nuclear Energy Institute (NEI), the policy organization of the nuclear energy industry, say that every U.S. nuclear power plant is designed to withstand an earthquake equal to the plant's maximum projected seismic event without any release of radioactive materials.

"Experts identify the potential ground motion for a given site by studying various soil characteristics directly under the plant," according to information available from the NEI. "As a result, the design requirements for resisting ground motion are greater than indicated by historical records for that site."

But other sources, like the owner and operator of the Oyster Creek nuclear power plant in New Jersey, are not so confident. According to a story that appeared last year in the Ocean County Observer in Toms River, only a few miles north of the plant, "Oyster Creek's steel and concrete radiation containment system has a 74 percent chance of failing if the reactor core melts or fuel is seriously damaged from an accident, according to a risk analysis by AmerGen Energy Co., which runs the plant. The details are in the plant's 2,400-page relicensing application."

"Part of the licensing procedure is the safety evaluation of each plant," said the NRC's Mitlyng.

"The nuclear industry and its regulators are willing to 'push the envelope' to preserve the ability of the industry to stay in business and make money," said Crocker. "At some point, one of the 400-plus reactors will again go over the edge, and the survivors will say, 'How could this happen?'" he said.

Allessandro Forte of the Université du Québec à Montréal and colleagues say the engine behind the quakes is an ancient, giant piece of the earth called the Farallon plate that started its descent under the West Coast 70 million years ago which is pulling the earth's crust down two-thirds of a mile from more than 360 miles beneath the Mississippi Valley.

Geologic formations that sink oceanic crust are called subduction zones, and the ones near Japan produce intense and damaging seismic activity. The Farallon plate is said to be a similar subduction zone deep inside the Earth below the central Mississippi River Valley.

According to the research team's projections, the Farallon plate will continue its descent into the mantle and cause mantle downwelling in the New Madrid region for a long time.

As quoted by CNN, Forte said, that this "suggests that the seismic risk in the New Madrid region will not fade with time."