Meltdown in Slow Motion

Without cooling, the nuclear fuel began to overheat. What followed was a terrifying sequence over four days:

• Reactor 1 — a hydrogen explosion blew the roof off the building on March 12
• Reactor 3 — a more violent hydrogen explosion on March 14 injured 11 workers
• Reactor 2 — the containment vessel was breached on March 15, releasing heavy radiation
• Reactor 4 — a fire in the spent fuel pool threatened a catastrophic release

All three active cores partially melted down. Workers pumped in seawater to cool them — a desperate move that ruined the reactors but prevented a far worse outcome.