Emergency workers in Japan tried every method imaginable to cool one of the country’s overheated nuclear reactors, including helicopters, heavy-duty fire trucks, and water cannons. But nothing has seemed to work; three of the reactors are in partial meltdown, and the pools used to store used nuclear fuel are going dry, meaning that the reactors’ internal rods could dangerously overheat and spew radiation. If the plants go into full meltdown, radiation will be released across a much larger area. U.S. Nuclear Regulatory Commission Chairman Gregory Jazcko said it could take "possibly weeks" to get the complex under control, and recommended a 50-mile evacuation radius—much larger than the area suggested by Japanese authorities. A U.N. official said there has been “no significant worsening” at the plant, but that the situation remains "very serious."