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Earthquake hits japan
An earthquake of magnitude 9.0 occurs of the eastern coast of Japan causing units 1, 2, and 3 of the Fukushima nuclear power plant to shut down automatically. Offsite power is lost and the Emergency Diesel Generators start to provide electricity to the power plant. -
Tsunami hits Japan an hour after the earthquake
The Tsunami strikes the Fukushima facility . This causes the Emergency Diesel Generators to stop working, leaving the power plant with no electricity at all. -
The core overheats
Due to the lack of electricity to power the cooling systems, the core is not being cooled and is now overheating at a dangerous rate and all citizens within 3 kilometers of the plant are evacuated. -
Hydrogen explosion occurs in unit one of the power plant
Backup battery suplies are depleted and the ability to cool the reactors of units one, two, and three is unavaliable. At this time all people within 10 kilometers of the plant are evacuated. A hydrogen explosion occurs in the unit one reactor building. -
Spent fuel is exposed to the atmosphere
The explosion destroys the structure where the spent fuel was stored causing the spent fuel to be exposed to the atmosphere. Seawater is injected into the unit one reactor in a desperate attempt to coo it down. at this point, anyone within the 20 kilometers of the power plant is evacuated. -
Hydrogen explosion in unit 2 reactor building
Damage is confirmed on the tiop levels of the unit 4 reactor building. Also, a fire is reported in unit 4. They begin venting the unit 2 primary containment. Another hydrogen explosion occurs this time in the unit 2 reactor building. -
Seawater is dumped in unit 3 spent fuel pool
Helicopters are used to dump the seawater into the spent fuel pool in an attempt to cool it off even just a little bit. -
Operational EDG powers units 5 and 6
An operational unit 6 EDG powers units 5 and 6. At this time spent fuel pool cooling begins for units 5 and 6. -
Units 5 and 6 reach cold shutdown conditions
The spent fuel pool temperatures at units 5 and 6 decrease thanks to Emergency Diesel Generators working for those units. After the temperatures decrease, units 5 and 6 are shutdown. -
Offsite power is avaliable to units 1, 2, 5, and 6
With offsite power avaliable to these units, They begin testing the equipment that was affected by the earthquake and tsunami in units 1 and 2. Also, the power to unit 5 is switched from the unit 6 EDG to offsite power. -
Offsite power is now avaliable to units 3 and 4
Now that units 3 and 4 have offsite power, all six units in the power plant have external power. The testing of components in units 1 and 2 continues before reconnecting the power at the two units. -
Core cooling is increased in unit 1
The unit 1 reactor almost reaches 400 degrees celcius, exceeding it's design value of 302 degrees celcius. Because of this the core cooling is dramatically increased. -
Fresh water is used to cool the reactors
The cleanup crew switched from using seawater to using fresh water to cool the reactors. They also put the fresh water in the spent fuel pools. -
Work begins on ventilation system
The crew begins to set up a ventilation system to improve the working environment inside the unit 1 reactor building. -
Temporaary cover installed over unit 1 reactor bulding
Work begins to install a temporary cover over the unit 1 reactor building to reduce the further spread of radioactive material. -
Japanese government releases report
The government of Japan releases a report containing analyses of damage to the cores of units 1-3. -
Three reactors are in stable state of cold shutdown
Japanese prime minister Yoshihiko Noda announces that three of the reactors damaged by the by the earthquake and tsunami are now in a stable state of cold shutdown. All three of these units are maintained at around 70 degrees celcius.
