Three Mile Island

The Three Mile Island Accident

The Three Mile Island Unit 2 reactor, located near Middletown, Pa., United States of America, partially melted down on 28 March 1979. This was the most serious accident in the history of US commercial nuclear energy plants. However, the small amount of radioactive release had no detectable health effects on plant workers or the public.

A combination of equipment malfunctions, design-related problems and worker errors led to the accident,

After the accident, changes were implemented in the nuclear industry, involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas. The US Nuclear Regulatory Commission states that all changes resulted in a safer operation of nuclear plants around the world.

As a result of the Three Mile Island accident, the Institute of Nuclear Power Operations (INPO) was established in Atlanta, Georgia, in 1979. INPO is a non-governmental organization that aims to promote the highest levels of safety and reliability in the operation of commercial nuclear plants. The Nuclear Energy Institute (NEI) states that the steady improvement in nuclear plant performance over the 30 years after the accident is proof of the positive impact INPO has had on the way plants are managed and operated.