Fairly Moderate Quake Motion Could Damage Protective System With AM-Weapons Reactor
WASHINGTON (AP) _ Fairly moderate earthquake ground motion could damage a major protective system of the Energy Department’s P-Reactor at the Savannah River Plant in South Carolina, a department official said Tuesday.
But major reactor components could withstand larger quakes, according to a report by Richard Starostecki, deputy assistant secretary for environment, safety and health to the department’s new Advisory Committee on Nuclear Facility Safety
The department plans to operate the P-Reactor for another year before beginning a major upgrade of its protection against earthquakes.
Starostecki presented DOE’s first numerical estimates of the ability of major systems of the reactor to come through earthquakes and still function. Studies aimed at similar estimates are under way for the two other nuclear weapons material production reactors at the Savannah River Plant.
Ground acceleration of about 1 foot per second per second would be enough to harm the filtration system designed to remove radioactive particles from air escaping from the reactor building in a major accident, Starostecki said.
In this ″confinement″ system, ″the limiting areas ... are primarily the filters″ - and at that acceleration, there is doubt ″that you can keep them up against the ductwork.″
Beyond about 3.2 feet per second per second, ″you probably don’t have confinement capability,″ Starostecki said.
One foot per second per second is about 3 percent of the acceleration that gravity imparts to a freely falling object, about 32 feet per second per second.
The acceleration due to gravity is called ″g,″ and engineers frequently express other accelerations as a fraction of ″g″ - 16 feet per second per second is 0.5g, 1 foot per second per second is 0.03g, and so forth.
People in a car accelerating steadily to 60 miles per hour in 15 second undergo an acceleration of a little less than 6 feet per second per second or 0.18g.
There is no necessary connection between ground acceleration and earthquake severity, said Ken Campbell, a civil engineer in the Boulder, Colo., office of the U.S. Geological Survey. Destructiveness ″is a function of duration of the shaking and its frequency content,″ as well as local geology, he said.
Campbell estimated that the 1886 earthquake centered 19 miles west of Charleston, S.C., caused ground accelerations of about 0.5g over the center of the earthquake, which has been estimated at 6.8 to 7.2 on the Richter scale.
Acceleration in the 1886 earthquake probably would have been less than 0.1g about 200 miles away, he said. Savannah River is about 115 miles northwest of Charleston.
According to Starostecki’s report, ground accelerations of 0.1g could disable the emergency cooling system. At 0.2g ability to shut down the reactor and remove its decay heat could be jeopardized.
Each year, there is a 1 per cent to 2 percent chance of an earthquake large enough to produce ground accelerations of 0.05g to 0.1g at Savannah River, said John Knight of Starostecki’s office. The chance of accelerations of 0.2g is about one in a thousand.
″As I see it, there is a crying need to sit back and say what are the seismic criteria for the site - no pun intended - from the ground up,″ Knight said. ″Keep in mind these systems were never subjected to a seismic analysis.″
Civilian reactors must be able to shut down in earthquakes of varying severity, with standards tailored to individual sites.
Frank Ingraham of the Nuclear Regulatory Commission said the most lenient is the site for the Yankee Rowe plant in Massachusetts, where shutdown must be possible in ground motions of 0.05g. The strictest is the Diablo Canyon site in California, close to a major fault, where shutdown must be possible in motions of 0.75g.