Newspaper: The Patriot
Date: March 30, 1979
Title: ‘Foul Up’ Sketched for Panel
Author: Peter J. Bernstein, of our Washington Bureau
WASHINGTON-Federal regulators told a panel of concerned members of Congress on Thursday that “multiple failures” in the cooling systems at Pennsylvania’s Three Mile Island power plant forced the reactor to overheat and send radioactivity seeping through the plant’s massive concrete walls into the surrounding environment.
“It was some foul-up,” said Joseph Hendrie, chairman of the Nuclear Regulatory Commission.
He acknowledged under questioning that a “similar” mechanical failure involving the plant’s cooling system occurred last Nov. 3, forcing the plant to shut down for repairs. The problem then was brought under control without any release of radioactivity.
This time, for reasons that weren’t immediately clear, he said, operators at the huge plant activated a rarely used emergency cooling system to keep enough water surrounding the reactor, then shut off the system only five minutes after it began operating.
Though the accident involved a greater degree of radioactive contamination than any other incident at a commercial reactor in U.S. history, the radiation in nearby communities is quite low and not dangerous to human life, he indicated.
He said federal monitors measured radioactivity levels to 20 millirems an hour a mile downwind from the plant. Exposure for three hours at that level, he said, is comparable to the radiation dose from a chest x-ray.
The radiation levels inside the reactor building, however, are a different matter. Instruments within the concrete containment building surrounding the reactor showed radiation levels of 20,000 millirems at the top of the building and levels of 10,000 millirems near the operating area, he said. Radiation would have to reach that intensity in order for gases to penetrate the four-foot thick containment walls.
In a hurriedly organized briefing for members of the House subcommittee on nuclear power, Hendrie said the NRC has launched an investigation into circumstances surrounding the accident at the $1 billion complex.
What is known is that the accident occurred about 4 a.m. Wednesday when a key part of the plant’s cooling system failed to function properly. Yet federal authorities weren’t notified until 7:45 a.m. Some state and local officials weren’t told about the accident until much later. “We still don’t know why,” he said.
The severity of the problem apparently wasn’t immediately recognized, he said, until high radiation levels began showing up in the cooling water.
He said that after the plant’s cooling system failed, the flow of water used to take the heat away from the reactor and generate steam was interrupted. This led to a stopping of the steam turbine and a consequent closing of the nuclear reactor.
However, even after a reactor is closed down it continues to generate enormous quantities of heat for some time. This heat apparently caused a buildup of pressure within the plant’s primary cooling system, which includes the reactor core.
To relieve that pressure, some radioactive water from the main cooling system had to be discharged into the lower level of the reactor containment building. The water reached six feet at one point.
At the same time, enough water had to be retained around the reactor to keep it from heating to dangerously high levels that could lead to a “melt-down” of the reactor core and a large release of radiation into the environment.
According to Darcell Eisenhut, deputy director of NRC’s Division of Operating Reactors, a plant operator, evidently fearing a possible melt-down, triggered the emergency cooling system.
“Five minutes after the emergency cooling system went on, it was turned off. We don’t know why, or the details, but it was turned off,” Eisenhut said.
What happened, he said, is that the resulting buildup of pressure within the reactor “blew open” a release valve, enabling radioactive gases to fill the containment building. “The release valve may have hung open,” he said.
“We’ve had a number of instances when relief valves have failed,” Hendrie told the subcommittee.
Although the plant at present is in “stable condition,” there was damage to reactor fuel rods and the inside of the containment building was seriously contaminated, Hendrie said. He said the damage was serious enough to keep the plant closed down for some time.
The plant, owned by General Public Utilities Co., (the parent company of Metropolitan Edison Co.) began operating late last year. The company’s other unit at Three Mile Island is currently is closed for routine maintenance. This unit is currently scheduled to return to operation early next month, though it couldn’t be immediately determined whether the accident at the other unit would affect that schedule. The two units can generate a total of about 1.7 million kilowatts of electricity.
Hendrie said the Pennsylvania plant is “typical” of many light water reactors currently operating in different parts of the country. Asked if NRC would shut down all such nuclear facilities as a precautionary measure, Hendrie said that would be unnecessary. “We haven’t seen anything this far that suggests generic problems” involving other plants, he said.
The accident, however, is the latest in a recent series of events that seem likely to damage seriously the cause of nuclear power, which already is in deep trouble.
Rep. Morris Udall, D-Ariz., chairman of the subcommittee which held the briefing, said the accident “is going to make us look harder and with a more skeptical eye at proposals to expand and expedite nuclear development.” He said this was another in a series of conventions of those who think we have rushed headlong into a dangerous technology without sufficient understanding of the pitfalls.”