A “closed” light didn’t prove the valve was closed. ⚠️ At Three Mile Island Unit 2, the pressurizer PORV opened and remained stuck open in 1979. The panel showed an electrical command to the solenoid, not the valve’s actual position, creating a critical gap in operator awareness. What evidence would you trust to confirm a component really moved? Save this case file and share it with someone who works with safety-critical systems. #ThreeMileIsland #NuclearSafety #HumanFactors #EngineeringFailures #SafetyEngineering #RiskManagement #ProcessSafety #ControlSystems #EngineeringHistory #CaseStudy - @amazeifystore