Period+1+-+TMI




 ** Interesting Facts **
 * Most serious accident in U.S. commercial nuclear power plant operating history
 * No deaths of injuries involved
 * Began about 4am on March 28th, 1979

** Major Causes **


 * Sequence of events:
 * equipment malfunction
 * design related problems & worker errors
 * Main feedwater pumps stopped running either by mechanical or electrical failure preventing the steam generators from removing heat
 * Turbine then the reactor automatically shut down
 * Pressurizer relief valve opened
 * The valve shoule have closed when the pressure decreased by a certain amount but it did not.
 * Signals failed to show that the valve was still open
 * Stuck-open valve caused the pressure to continue to decrease in the system
 * Another problem arised somewhere else in the plant
 * Emergency feedwater system (backup to main feedwater) was tested 42 hours prior to accident during this the valve was closed and reopened at the end of the test. But this time through either an administrative or human error, the valve wasn't reopened preventing the emergency feedwater system from functioning
 * The closed valve wasn't discovered til 8 minutes into the accident after the emergency feedwater system began to work correctly, allowing cooling water to flow into the steam generators
 * As the pressure in the primary system continued to decrease, voids (areas with no water present) began to form in portions of the system other than the pressurizer. Because of this the water in the system was redistributed and the pressurizer was full of water.
 * Because adequate cooling wasn't available, the nuclear fuel overheated to a point where some of the zirconium cladding reacted with the water and generated hydrogen. Hydrogen was released into the reactor containment building.
 * led to significant damage to the Three Mile Island #2 reactor core but only very small off-site releases of radioactivity

** Major Details **

> the plant. > > >      **Laws and Policies Resulting from TMI**
 * The accident of Three Mile Island resulted in the temporary closure of all nuclear power stations of a similar design.
 * The accident significantly stalled the development of nuclear power in the USA.
 * The accident released radioactive water and gases into the environment.
 * Uncertain about how much radiation had been released beyond the building, experts recommended that children and pregnant women leave the area.
 * Of the short-term effects, the loss to business, totaling around $81.9 million, constituted the greatest impact.
 * The evacuation costs to households reached only $5.99 million.
 * Health-related costs were the smallest expenditure resulting from the TMI crisis.
 * Long-term economic effects were not large for people living in the immediate vicinity of
 * There was no indication of any significant change in property values near TMI due to the accident.
 * Most of the evacuations occurred on Friday, three days after the accident.
 * During the crisis period there was evidence of a 10% increase in reports of intense distress among people living close to the facility.




 * New training procedures for all operators and staff
 * Obtaining a lisence to open a new plant became more difficult
 * The Nuclear Regulatory Commission (NRC) expanded its resident inspector program, which is when 2 inspectors live near the plant and are involved in the daily activities of the plant
 * Performance-oriented as well as safety-oriented inspections made more often
 * Upgrading plant design
 * New emergency alert systems
 * Institute of Nuclear Power Operations (INPO) established, which basically makes all the rules
 * Greater international involvement in nuclear discussions
 * NRC began to publish a periodical report on the  performance and effectiveness of the plants
 * Enforcement of regulations becomes a higher priority    


http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html http://en.wikipedia.org/wiki/Three_Mile_Island_accident http://www.tmia.com/ //Three Mile Island: A Nuclear Crisis in Historical Perspective.// J Samuel Walker. Los Angeles: University of California Press. 2004. http://www.world-nuclear.org/info/inf36.html?terms=Three+Mile+Island "Three Mile Island" //A Dictionary of Contemporary World History//. Jan Palmowski. Oxford University Press, 2008. //Oxford Reference Online//. Oxford University Press. Cumberland Valley High School. 30 October 2008 http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t46.e2314 "Three Mile Island" //World Encyclopedia//. Philip's, 2008. //Oxford Reference Online//. Oxford University Press. Cumberland Valley High School. 30 October 2008 http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t142.e11552 Charles Perrow, //Normal Accidents: Living with High-Risk Technologies//, 1984 .John L. Campbell , //Collapse of an Industry: Nuclear Power and the Contradictions of U.S. Policy//, 1988. http://www.policyalmanac.org/environment/archive/three_mile_island.shtml http://www.questia.com/PM.qst?a=o&d=99374020


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