(CNN) Eight years after a 9.0 magnitude earthquake triggered Japan's worst ever nuclear disaster, work has begun to remove spent fuel rods from a reactor that went into meltdown at Fukushima Daiichi nuclear power station.

Three reactors partially melted down at the plant, operated by Tokyo Electric Power Co. (TEPCO), in the wake of the earthquake and subsequent tsunami on March 11, 2011, as radioactive material leaked into the air and the Pacific Ocean.

Japan's nuclear agency deemed the incident a Level 7 event --- the highest level of nuclear crisis, matched only by the Chernobyl disaster of 1986.

As the Fukushima plant was melting down, more than 300,000 people living nearby were evacuated, according to the Red Cross.

More than 20,000 people died or went missing in the quake and tsunami, while hundreds of thousands more lost their homes.

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