On the afternoon of March 11th, 2011 - a massive 9.0 earthquake struck just off the main island of Japan - rattling the nation to its core. Nestled on the east coast of Japan - not too far from the epicenter of that quake - was the Fukushima Daiichi Nuclear Plant - a plant with six nuclear reactors - three of which weren't designed to handle an earthquake of that magnitude. Right after the ground started shaking - reactors 1, 2, and 3 at the plant went into automatic shutdown. Reactors 4, 5, and 6 were already shutdown for inspection. The main power source to keep the reactors cool - the electric grid - was knocked out by the earthquake - so 13 emergency diesel generators immediately kicked in to keep the reactors cool. But within ten minutes, the emergency cooling systems at reactor 1 failed - and radioactive fuel rods within the reactors began to melting down.

But things were about to get a lot worse. Approximately 50 minutes after the earthquake - a giant 45-foot tsunami slammed into the east coast of Japan - and right into the Fukushima Daiichi plant. It swept across the plant's seawalls - and flooded the turbine buildings - shutting down the emergency diesel generators - and cutting off critical cooling to the reactors. At this point - the operators of the Fukushima plant knew they had a crisis on their hands. At approximately 3:41 in the afternoon - less than an hour after the earthquake - TEPCO, which operated the plant, notified the authorities that they had a "First level Emergency" on their hands - reactors were melting down. To buy themselves time - operators begin relieving pressure from the reactors - by releasing radioactive steam out of the reactor buildings and into the air.

And in a frantic attempt to keep the reactors cool - nearby seawater is pumped into the plant. But that wasn't enough - and there's not much else that plant operators can do, since the radiation around the plant was spiking. Soon - reactor buildings begin exploding. One day after the earthquake - on March 12th - reactor 1 suffered a hydrogen explosion - collapsing its roof. Over the next few days - reactors 2, 3, and 4 would give way to similar hydrogen explosions - mangling the reactor buildings - and exposing highly radioactive spent fuel - which was stored in pools built into the ceilings of the reactors - to the atmosphere. Helicopters flew in to drop seawater into the crippled reactor buildings, trying to prevent the spent fuel pools from igniting.