Three Mile Island is a nuclear power plant located in Pennsylvania, USA. It became famous for a partial meltdown that occurred on March 28, 1979. This incident was the most serious accident in U.S. commercial nuclear power plant history, leading to widespread public concern about nuclear safety. The accident was caused by a combination of mechanical failures and human errors. Although there was no significant release of radiation, the event prompted changes in regulations and safety protocols for the entire nuclear energy industry. It also influenced public perception of nuclear power for years to come.