Historical Event-Three Mile Island

In 1979 there was a core meltdown at Three Mile Island. In Dauphin, Pennsylvania near Harrisburg. The accident began at 4:00 AM March 28, 1979. A cooling malfunction caused part of the core to melt in the #2 reactor. Up to 13 million curies of radioactive noble gases, but less than 20 curies of the hazardous iodine were released. The mechanical failures were compounded by the failure of plant operators to recognize the problem due to poor training. They did not see the failures in the non-nuclear secondary system, followed by a stuck pilot operated relief valve in the primary system, which allowed large amounts of reactor coolant to escape. Some radioactive gas was released a couple of days after the accident, but not enough to cause any dose above backgrounds levels to local residents. There were no injuries or health effects from the accident.
The #2 reactor took nearly 12 years and cost approximately $973 million to clean up the damage. The surfaces had to be decontaminated. Water used and stored during the clean up had to be processed. About 100 tons of damaged uranium fuel had to be removed from the reactor.