Did You Know the U.S. Came Seconds From a Nuclear Disaster? The Three Mile Island accident was the most serious accident in U.S. commercial nuclear power history. #ThreeMileIsland, #NuclearAccident, #Meltdown, #NuclearEnergy, #Radiation, #HistoryFacts, #DidYouKnow, #NuclearSafety, #EnergyCrisis, #ScienceHistory, #HistoricEvents, #USAHistory, #AtomicAge, #NuclearPower, #Disaster, #SafetyFirst, #NuclearThreat, #EmergencyResponse, #Harrisburg, #1979, #NuclearEngineering, #OperatorError, #PartialMel