The Kyodo news agency reported that the cooling system has failed at three reactors of Fukushima No. 2 nuclear power plant. The coolant water's temperature had reached boiling temperature, the agency reported, citing the power plant's operator, Tokyo Electric Power.
The cooling system failure at the No. 2 power plant came after officials were already troubled by the failure of the emergency cooling system at the Fukushima No. 1 plant, which officials feared could cause a meltdown.
Photos: Scenes from the earthquake
Authorities have ordered the evacuation of all civilians in a two-mile radius around the No.1 plant, a total of about 3,000 people, and planned to vent slightly radioactive steam from the plant, located about 160 miles north of Tokyo.
A properly functioning cooling system is critical to keep radioactive material from escaping the nuclear reactor's containment zone.
Videos of the earthquake
For more: Post-quake events at Japan nuclear plant raise concerns