March 28, 1979 America's worst commercial nuclear accident occurred inside the Unit 2 reactor at the Three Mile Island plant near Middletown, Pa. The accident began about 4:00 a.m. on March 28, 1979, when the plant experienced a failure in the secondary, non-nuclear section of the plant. The main feedwater pumps stopped running, caused by either a mechanical or electrical failure, which prevented the steam generators from removing heat. First the turbine, then the reactor automatically shut down. Immediately, the pressure in the primary system (the nuclear portion of the plant) began to increase. In order to prevent that pressure from becoming excessive, the pilot-operated relief valve (a valve located at the top of the pressurizer) opened. The valve should have closed when the pressure decreased by a certain amount, but it did not. Signals available to the operator failed to show that the valve was still open. As a result, cooling water poured out of the stuck-open valve and caused the core of the reactor to overheat.
As coolant flowed from the core through the pressurizer, the instruments available to reactor operators provided confusing information. There was no instrument that showed the level of coolant in the core. Instead, the operators judged the level of water in the core by the level in the pressurizer, and since it was high, they assumed that the core was properly covered with coolant. In addition, there was no clear signal that the pilot-operated relief valve was open. As a result, as alarms rang and warning lights flashed, the operators did not realize that the plant was experiencing a loss-of-coolant accident. They took a series of actions that made conditions worse by simply reducing the flow of coolant through the core.
Because adequate cooling was not available, the nuclear fuel overheated to the point at which the zirconium cladding (the long metal tubes which hold the nuclear fuel pellets) ruptured and the fuel pellets began to melt. It was later found that about one-half of the core melted during the early stages of the accident. Although the TMI-2 plant suffered a severe core meltdown, the most dangerous kind of nuclear power accident, it did not produce the worst-case consequences that reactor experts had long feared. In a worst-case accident, the melting of nuclear fuel would lead to a breach of the walls of the containment building and release massive quantities of radiation to the environment. But this did not occur as a result of the three Mile Island accident.
Detailed studies of the radiological consequences of the accident have been conducted by the NRC, the Environmental Protection Agency, the Department of Health, Education and Welfare (now Health and Human Services), the Department of Energy, and the State of Pa.. Several independent studies have also been conducted. Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a chest x-ray is about 6 millirem. Compared to the natural radioactive background dose of about 100-125 millirem per year for the area, the collective dose to the community from the accident was very small. The maximum dose to a person at the site boundary would have been less than 100 millirem.
1978 In Stump v. Sparkman, the U.S. Supreme Court voted 5-3 to uphold the judicial immunity of an Indiana judge against a lawsuit brought by a young woman who had been ordered sterilized by the judge when she was a teenager.
In 1971 Judge Harold D. Stump, of the Circuit Court of DeKalb County, Indiana, acted on a petition filed by Ora Spitler McFarlin, the mother of fifteen-year-old Linda Spitler. McFarlin sought to have her daughter sterilized on the ground she was a "somewhat retarded" minor who had been staying out overnight with older men.
Ten years ago the authors of a book on the Oklahoma City bombing revealed that during prison interviews, Timothy McVeigh had shown no remorse for what happened, and called the 19 children who died "collateral damage."
Thought for today "Those who say they give the public what it wants begin by underestimating public taste and end by debauching it." — T.S. Eliot, American-Anglo poet and critic (1888-1965)
Over and out.
As coolant flowed from the core through the pressurizer, the instruments available to reactor operators provided confusing information. There was no instrument that showed the level of coolant in the core. Instead, the operators judged the level of water in the core by the level in the pressurizer, and since it was high, they assumed that the core was properly covered with coolant. In addition, there was no clear signal that the pilot-operated relief valve was open. As a result, as alarms rang and warning lights flashed, the operators did not realize that the plant was experiencing a loss-of-coolant accident. They took a series of actions that made conditions worse by simply reducing the flow of coolant through the core.
Because adequate cooling was not available, the nuclear fuel overheated to the point at which the zirconium cladding (the long metal tubes which hold the nuclear fuel pellets) ruptured and the fuel pellets began to melt. It was later found that about one-half of the core melted during the early stages of the accident. Although the TMI-2 plant suffered a severe core meltdown, the most dangerous kind of nuclear power accident, it did not produce the worst-case consequences that reactor experts had long feared. In a worst-case accident, the melting of nuclear fuel would lead to a breach of the walls of the containment building and release massive quantities of radiation to the environment. But this did not occur as a result of the three Mile Island accident.
Detailed studies of the radiological consequences of the accident have been conducted by the NRC, the Environmental Protection Agency, the Department of Health, Education and Welfare (now Health and Human Services), the Department of Energy, and the State of Pa.. Several independent studies have also been conducted. Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a chest x-ray is about 6 millirem. Compared to the natural radioactive background dose of about 100-125 millirem per year for the area, the collective dose to the community from the accident was very small. The maximum dose to a person at the site boundary would have been less than 100 millirem.
1978 In Stump v. Sparkman, the U.S. Supreme Court voted 5-3 to uphold the judicial immunity of an Indiana judge against a lawsuit brought by a young woman who had been ordered sterilized by the judge when she was a teenager.
In 1971 Judge Harold D. Stump, of the Circuit Court of DeKalb County, Indiana, acted on a petition filed by Ora Spitler McFarlin, the mother of fifteen-year-old Linda Spitler. McFarlin sought to have her daughter sterilized on the ground she was a "somewhat retarded" minor who had been staying out overnight with older men.
Ten years ago the authors of a book on the Oklahoma City bombing revealed that during prison interviews, Timothy McVeigh had shown no remorse for what happened, and called the 19 children who died "collateral damage."
Thought for today "Those who say they give the public what it wants begin by underestimating public taste and end by debauching it." — T.S. Eliot, American-Anglo poet and critic (1888-1965)
Over and out.
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