Little Bits of History

Three Mile Island

Posted in History by patriciahysell on March 28, 2011

Three Mile Island

March 28, 1979: At precisely 4:00 AM the water pump in the nuclear reactor cooling system at Three Mile Island, Tower 2, failed resulting in a partial nuclear meltdown. The nuclear power plant was built on an artificial island [Three Mile Island] in the Susquehanna River near Harrisburg, Pennsylvania. The plant was built as twin pressurized water reactors with the towers named TMI-1 and TMI-2. The meltdown occurred in TMI-2.

TMI-1 came online April 19, 1974 and is licensed to operate until the same date in 2014. TMI-2 came online in December 1978 and operated only about 90 days. Loss of coolant led to the meltdown and is considered the worst nuclear accident in the US. At the time, it was the worst in the world but the Chernobyl accident in 1986 proved far more devastating.

Three Mile Island, while causing no deaths or even injuries, was still catastrophic. It took five days and many government, business, and safety agencies to determine that the residents in the surrounding areas were not required to make a full evacuation. Because of this accident, public opinion concerning nuclear energy dropped from a 70% approval rating to a 50% rating. Cleanup began in August of 1979 and continued through December 1993 at a cost of $975 million. The end result was that TMI-2 was closed forever.

When the cooling pumps failed to work, heat built up in the reactor with an increase in steam buildup as well. Increased pressure opened a safety valve that should have released pressure and then closed, but instead, remained open. About 80 minutes after the initial problem, the cooling pumps shut down completely. After 130 minutes of elapsed time, the top of the reactor core was exposed and the intense heat damaged the nuclear fuel rods. Another 35 minutes elapsed before the radiation alarms were activated. Even though approximately one-half of the fuel melted, the reactor vessel contained the damaged fuel. President Carter and the Pennsylvania House of Representatives called for a full investigation. Human error, while not responsible, was a contributory factor and it was found that dials and gauges could have been better and more safely designed.

“The more human beings proceed by plan the more effectively they may be hit by accident.” – Friedrich Dürrenmatt

“A man ever supports great and inevitable misfortunes with more calmness and resignation than trifling accidents.” – unknown

“Fast-growing global energy demands, an increased emphasis on the security of energy supply, and the risk of climate change are driving a renewed consideration in many quarters towards investment in nuclear power.” – Mohamed ElBaradei

“A nuclear power plant is infinitely safer than eating, because 300 people choke to death on food every year.” – unknown

Also on this day:
Ragnar, the Viking – In 845, Ragnar sacked Paris.
Palm Sunday tornado – In 1920, a series of tornadoes broke out.

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