Updated

The radioactive water that has accumulated at Japan's crippled nuclear power plant remains the biggest problem hampering the cleanup process three years after the disaster.

The Fukushima Dai-ichi plant has stabilized substantially since the March 11, 2011, earthquake and tsunami destroyed its power and cooling system, triggering multiple meltdowns. Massive amounts of water are being used to cool the plant's nuclear material, but the contaminated water has leaked repeatedly from storage tanks.

Plant chief Akira Ono said Monday that improving water management is crucial to the decontamination of the area so evacuees can return to their homes.

The disaster is the world's worst atomic accident since Chernobyl in 1986. More than 100,000 people have not returned home due to fear of radiation from the plant.