Emergency Declared at Japanese Nuclear PlantBy MATTHEW L. WALD
Published: March 11, 2011
...Some 6,000 people were told to leave a 2-mile radius around the Fukushima No. 1 plant, operated by Tokyo Electric Power and located in Fukushima Prefecture, after a mechanical failure in the cooling system of the facility, government officials said.
The evacuation was described as precautionary. Near midnight Japan time on Friday, Jiji Press, a Japanese news agency, quoted officials as saying that the cooling system would be reactivated and resume normal operations...
...Trouble was reported at two other nuclear plants in Japan as well, but there was no radiation leak at either of them, government officials said.
One major concern is that while operators can quickly shut down a nuclear reactor in an earthquake or during another emergency, they cannot allow the cooling systems to stop working. Even after the plant’s chain reaction is stopped, its fuel rods still produce heat. This is because they are filled with radioactive materials that are still throwing off sub-atomic particles or gamma radiation, which generates heat...
http://www.nytimes.com/2011/03/12/world/asia/12nuclear.html?hp