Three+Mile+Island

Three Mile Island Accident, 1979

On March 28, 1979 just outside of Harrisburg, Pennslyvannia, a cooling malfunction at a nuclear power plant caused a mass amount of radiation to be released. This accident became known as one of the worst accident in the history of nuclear power with the release of 43,000 curies of radioactive materials. Although no injuries or deaths occured, this led to many drastic reforms in emergency response planning for nuclear power plants. Because of a series of events beginning with equipment and human error, a partial meltdown of the core occured and caused the release of radioactivity into the enviornment.

__**What Happened**__ Beginning on March 28th, 1979 at 4:00 a.m., a secondary section of the Three Mile Island Nucleur plant failed and the feedwater pumps stopped running due to mechanical and electrical failure. This stopped the steam generators from removing heat from the core of the plant causing it to begin to overheat. After this, pressure began to build up which caused the pilot-operated relief valve to open and, for an unknown reason, not close again. This caused a large amount of water, which was suppose to stay in the valve, to pour out. Because there was no way for the mechanics to know whether the valve was open or not, they believed that it was closed and, as a result, had no idea that cooling fluid was escaping through the valve. By this point the core was becoming very overheated and the fuel pellets were begininning to melt. If the core had increased in temperature, it would melt the chamber that housed it and would melt into the earth, contaminating an aquarfir beneath the complex. Many years later scientists discovered that over half the core had melted during the meltdown. By that evening everything was thought to be stable until March 31st, when a large hydrogen bubble appeared. If this bubble were to explode, it would leak radiated water into the environment and potentialy harm the 25,000 people that lived close to the plant. Tests later discovered that the bubble could not burst and was therefore harmless to the plant. This accident could have had very harmful and drastic effects due to the number of mechanical and human errors, but luckily resulted in no injuries or deaths. The accident occured at 4:00 am Eastern standard time on March 28, 1979. This was the exact minute when the power plant was opened and ready to produce energy.

The Three Mile Island incident caused a precedent for heightened security measures and increased regulation on building powerplants. The meltdown had a psychological impact on the American public as well. Before the accident, 70 percent of the public prefered nuclear power due to its lack of toxic output. After the accident, only 50 percent of the public prefered nuclear powerplants. The accident also started a decline in the production of nuclear powerplants. In 1979, 129 powerplants recieved aproval from the US government. But after the accident, only 53 plants were constructed or in construction. The incident also took a financial toll on the US government; the clean-up of the accident cost $975 million to remove the waste. In addition, the media tarnished the reputation of nuclear power further by releasing a film called "The China Syndrome," about a nuclear reactor going critical and almost melting down before the disaster was averted by the protagonist.
 * __Aftermath__**





- Diagram of how a reactor core is cooled.

media type="youtube" key="jxH9N3N1L08&hl=en&fs=1" height="344" width="425"-Movie describing the accident Sources: [|wikipedia.org], [|youtube.com]