Period+4+-+TMI

**Three Mile Island**

TMI occured at 4 a.m. on March 28th, 1979 near Middletown, PA and was the most serious accident in U.S. commercial nuclear power plant opperating history. TMI experienced a failure in the secondary non nuclear section of the plant which caused the temperature in the primary coolant to rise. This is what made the power plant shut down automatically. The feedwater pumps also stopped running. Due to the inadequate emergency response and the deficient control room instrumentation training proved to be root causes of the accident. However, no deaths or injuries occured because of this accident. Throughout the morning workers forced water into the reactor system to condense steam bubbles which blocked the flow of cooling water. The attempt was made to decrease the pressure in the reactor system. Later that evening they restored forced cooling of the reactor core when they were able to restart one reactor cooling pump. They condensed the steam so the pump could run with severe vibrations. The reactors fuel core became uncovered and more than one third of the fuel melted. There was conflicting news to the public about the event which created confusion and worry. It was clear that there was no "China Syndrome" resulting from this. The hydrogen bubble, a high temperature chemical reaction between water and the zircally metal tubes holding the nuclear fuel pellets, created hydrogen gas. The hydrogen gas bubble was removed from March 30th - April 1st. On April 27th instead of using mechanical pumping, natural movement of water was used. The plant was in "cold shutdown". Since then they have training improvements with their employees. The training became centered on protecting plants and cooling capacity. INPO was formed in 1979 which is the Institute of Nuclear Power Operations. It promotes the operation of nuclear plants and making their training programs better. TMI was a major cause of the decline of nuclear construction throught the 1980s and 1990s.
 * __The Details and Major Causes of Three Mile Island__**
 * __New Improvements__**

Web Sources: www.world-nuclear.org

http://www.atomicarchive.com/History/coldwar/images/tmi.jpg

http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/Tmi-2_schematic.svg/575px-Tmi-2_schematic.svg.png

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