Three Mile Island

On March 28, 1979, following a breakdown of the cooling system’s water feed pumps at the electricity power station on Three Mile Island in Pennsylvania (USA), the core of a nuclear reactor began to melt down. The confinement enclosures nonetheless resisted and there were no victims as a result of the accident, which was restricted to the release of radioactive vapour which caused in some workers an exposure to radiation which was hardly greater than that of natural radioactivity. This incident nonetheless led to a thoroughgoing review of the security procedures and the construction methods for this type of nuclear power station.