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Accidents on Commerical Reactors


Serious Accidents on Commercial Reactors

  The two well-known accidents on commercial nuclear reactors occurred at Chernobyl in 1986 and Three Mile Island in 1979 had significant impact to the nuclear industry around the world. It had brought about major changes to the design of nuclear power plants to ensure nuclear safety, particularly in enhancement of operator training and emergency planning.
  Occurrence of the Chernobyl accident on April 26, 1986 was mainly due to a combination of severe design deficiencies of the reactor and its shutdown system, coupled with violation of procedures when conducting an experiment on the reactor unit. The Chernobyl-type accident could not occur at the nuclear power stations in Daya Bay which have reactors of entirely different design.

The cause of the accident at Three Mile Island (TMI-2) was apparently attributed to a combination of component failure, deficient instrumentation, and human errors. The operators were unable to diagnose or respond properly to a "loss of coolant accident" due to a defective pressure relief valve. Although there was a partial melting of the reactor core at TMI-2, the radiological release was mainly confined within the containment building and the release to the environment is minimal and insignificant. There were also no injuries or adverse health effect as a result of the accident.

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