mime221_essay_TMI_final

mime221_essay_TMI_final - After the magnificent discovery...

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After the magnificent discovery of nuclear reactions in the last century, Albert Einstein, one of the greatest thinkers of those times, once remarked, “There is not the slightest indication that nuclear energy will ever be obtainable.” (1) Nowadays, despite this brave prediction, humans take full advantage of this energy source at no surprise to anyone; yet, many still question whether this advancement is absolutely safe to our health and environment, and these beliefs are not unreasonable. One of the largest impacts on people and the industry was made by the nearly catastrophic Three Mile Island nuclear accident that occurred near Middletown, Pennsylvania, USA. In the early morning of March 28, 1979, the Unit 2 (TMI-2) (2) of the plant experienced a major failure: the central feed-water pumps stopped functioning, preventing heat removal from the steam generators. The turbine and the reactor shut down, increasing the pressure inside the pressurizer. Automatically, the relief valve opened, but got stuck-open once the pressure stabilized. The malfunction was not noticed by the operator, and the coolant poured out of the valve, causing core overheating. Meanwhile, the control room indicators were not able to show the actual level of coolant water in the reactor core; the operators could only see the level of water in the pressurizer which was unallowably high, and because of that, they wrongly supposed that the core was fully covered with water. There still was no visible indication that the relief valve was open. Not being able to identify the loss-of-coolant situation, the operators turned off the automatic emergency- cooling system and almost all of the emergency pumps, reducing the flow of coolant through the core even more. (5) Without cooling, the fuel casing material reacted with the steam and produced hydrogen which then escaped into the containment structure and exploded. This, fortunately, did not lead to a breach in the containment walls. (2) The nuclear rods overheated and the pellets began to melt. Next shift’s crew arrived and managed to block the relief valve, then contacted Babcock & Wilcox and the Nuclear Regulatory Commission (NRC), (5) however, for the latter one, they could only leave a message. The regional office sent the first team of inspectors to the site and, as the radioactivity levels were already raising, all but essential personnel was ordered to leave the plant.
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This note was uploaded on 12/01/2009 for the course MIME MIME 221 taught by Professor Hassani during the Winter '08 term at McGill.

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mime221_essay_TMI_final - After the magnificent discovery...

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