Inside Fukushima I (Dai-Ichi), Nuclear Power Plant, Japan

On November 2, 2010 unit 5 had an automatic SCRAM while an operator was conducting an adjustment to the control blade insertion pattern. The SCRAM was caused by a reactor low water level alarm. The turbine tripped along with the reactor and there was no radiation injury to workers.
Nuclear accidents of 2011
On 11 March 2011 an earthquake categorised as 9.0 MW on the moment magnitude scale occurred at 14:46 Japan Standard Time (JST) off the northeast coast of Japan. Units 4, 5 and 6 had been shut down prior to the earthquake for planned maintenance. The remaining reactors were shut down automatically after the earthquake, and the remaining decay heat of the fuel was being cooled with power from emergency generators. Then, the subsequent tsunami disabled emergency generators required to cool the reactors. Over the following three weeks there was evidence of a partial nuclear meltdown in units 1, 2 and 3; visible explosions, suspected to be caused by hydrogen gas, in units 1 and 3; a suspected explosion in unit 2, that may have damaged the primary containment vessel; and a possible uncovering of the units 1, 3 and 4 spent fuel pools. Radiation releases caused large evacuations, concern over food and water supplies, and treatment of nuclear workers.