The latest worry concerns the corrosive nature of the seawater that's been used to stabilize temperatures since a tsunami knocked out the complex's cooling system more than two weeks ago. The fear is that salt and other contaminants in the seawater could cause pipes to clog and coat the surface of reactor vessels and fuel rods, hampering the cooling process.
Japan's nuclear safety agency says plant operators are trying to inject fresh water, and U.S. naval barges are on their way to the site loaded with half a million gallons of it.
Radiation has been seeping from the plant since a magnitude-9 earthquake and the tsunami struck, making its way into milk, seawater and vegetables grown in the area. Tap water in several areas, including Tokyo, has shown higher-than-normal levels of radiation. But the levels have fallen steadily since peaking Wednesday, and officials say Tokyo's tap water is now safe for babies to drink.
