“Within 4 seconds, the reactor’s energy output had soared to several times its intended capacity. Runaway heat and pressure deep inside the core ruptured fuel channels, then water pipes, causing the pumps’ automatic safety valves to close. This stopped the flow of coolant, increasing the rate at which steam was forming from the core’s diminishing water supply. The reactor’s own safety valves attempted to vent the steam, but the pressure was too great and they, too, ruptured.”
