When the Fukushima Daiichi nuclear disaster began on 11 March 2011, reactor unit 4 was shut down and all fuel rods had been transferred to the spent fuel pool on an upper floor of the reactor building.
Reactor unit 4 was shut down. The Fukushima Daiichi nuclear disaster began on 11 March 2011. All fuel rods had been transferred to the spent fuel pool on an upper floor of the reactor building.