Japanese news agency Kyodo on Sunday, Mar 13 reported that The cooling system had stopped working in a sixth reactor.
Kyodo agency also reported that radiation levels have risen above the safety limit around Tokyo Electric Power Co's (TEPCO) nuclear plant hit by a massive earthquake and the company has informed the government of an "emergency situation".
After several tests, 18 people reportedly were found poisned by the radiation leak and the total death toll is estimated to cross 1,800.
Japan ordered to evacuate almost 170,000 people from the area near the damaged nuclear power plant, informed the UN nuclear watchdog. People were ordered out of a 20-kilometre radius surrounding the Fukushima, sources reported.
Earlier reports showed that the explosion was not of the reactors, but occurred in the plant. The outer wall of the building holding the first reactor was blown off in the impact.
Authorities informed that if the cooling system remains inoperative for many hours, the water will eventually boil away, and the fuel will begin to melt.
However, Secretary of States, Hillary Clinton informed, "We just had our Air Force assets in Japan transport some really important coolant to one of the nuclear plants." Confirming Clinton's statement, Presindent Barack Obama also earlier claimed, "So Air Force planes were able to deliver that. So we're really deeply involved in trying to do as much as we can on behalf of the Japanese and on behalf of US citizens."
The crisis at the aging plant confronted Japan with its worst nuclear accident and perhaps the biggest mishap at nuclear plant since the Chernobyl nuclear disaster in 1986.