Three+Mile+Island

=Three Mile Island=

Overview
Three Mile Island is remember for the nuclear meltdown at its nuclear power station in 1979. The power plant was constructed on an island of the Susquehanna River in central Pennsylvania, 10 miles south of Harrisburg. The Three Mile Island Unit 1 nuclear reactor began creating energy for the public September 2, 1974. On the last day of 1978, Three Mile Island Unit 2 started the same thing. Only months into operation, this reactor underwent a serious problem. The trouble began with the malfunction at 4:00 AM March 28, 1979 of the main water pumps, located away from the nuclear reactors. Because of this error, the nuclear reactor turned off automatically; the pressure increase created in the coolant system was counteracted by opening the relief valve. The critical failure was the relief valve didn't close when the pressure subsided, lowering the nuclear core's coolant below necessary levels and no instrument specifically signaled this problem. The employees, not knowing the true cause of the overheating reactor, attempted a series of actions, one of which was to lower the coolant in the reactor.

Central Issue
The core began a meltdown, in which the zirconium rods holding the fuel pellets cracked under the environment, allowing the nuclear fuel to melt. If this fuel was able to escape the plant's containment, the entire region surrounding Three Mile Island could experience harmful radiation levels. The situation was presented to the White House by 9:15 AM. Organizations like the NRC, EPA, and Department of Energy observed the scenario and prepared for what might come. All unnecessary people at the facility were instructed to leave by 11:00 that morning. Traces of radioactive gases were discovered beyond the reaches of the plant. By the day's end, it appeared as if the scare was over as the reactor had cooled. When radiation was monitored being given off from a building made to regulate pressure to and coolant for the reactor, a new wave of fear arrived. The governor of Pennsylvania ordered the evacuation of all pregnant women and children below school age in a five-mile radius of the plant.

Conclusion/Historical Significance
The final problem encountered was the formation of a bubble of hydrogen in the structure housing the reactor's core. If the hydrogen was able to explode, the structure might break, allowing the nuclear material to seep out. This issue was resolved by April 1 once the bubble had been reduced in size and experts concluded the bubble could not combust because the structure was void of oxygen. The crisis was over. Three Mile Island Unit 2 was completely cleaned out of all hazardous materials over the next 14 years and decommissioned. Unit 1 currently continues to provided power, but once its license runs out, it will cease operations too. The incident at Three Mile Island was not important because of the radiation it exposed to the nearby citizens—it was approximately an extra 3-4 average days worth of radiation for them. The reason this event still matters is it had a major affect on the future of power in our country. Before the Three Mile Island incident, most Americans worried little about the dangers of nuclear power. Afterwards, people were uneasy about these radiation producers. Since the meltdown, not a single new nuclear power plant has been constructed in the United States.