This is very, very bad news for the people of Japan and those living in areas where radiation may be carried:
The United States expressed increasing alarm Wednesday about the the threat posed by Japan's nuclear crisis, with its top nuclear energy chief suggesting that one crippled reactor was in danger of a complete meltdown.
The U.S. urged Americans to evacuate a wider area around the plant. Other governments advised their citizens to leave the country altogether.
Amid the controversy, Japan's military dropped water from two helicopters onto another crippled reactor.
Gregory Jaczko, chairman of the U.S. Nuclear Regulatory Commission, painted a much bleaker picture of the situation at the Fukushima Dai-ichi plant than Japanese officials. He told a congressional hearing in Washington that all the water was gone from the spent fuel pools at Unit 4, one of six reactors at the complex.
"There is no water in the spent fuel pool and we believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures," he said.
Japanese officials denied that all the cooling water was gone. Hajime Motojuku, spokesman for plant operator Tokyo Electric Power Co., said the "condition is stable" at Unit 4.
If Jaczko is correct, it would mean there's nothing to stop the fuel rods from getting hotter and ultimately melting down. The outer shells of the rods could also ignite with enough force to propel the radioactive fuel inside over a wide area.
Jaczko did not say how the information was obtained, but the NRC and U.S. Department of Energy both have experts at the Fukushima complex along Japan's northeastern coast, which was ravaged by last week's magnitude-9.0 earthquake and subsequent tsunami.
