An explosion at the Fukushima Dai-ichi power plant in northern Japan on March 12 blew the roof off one building and destroyed the exterior walls of a crippled reactor, but officials said the steel containment core around the reactor had not been breached, and denied that a major meltdown was imminent. Government officials and executives of Tokyo Electric Power gave what the New York Times called "confusing accounts" of the causes of the explosion and the damage it caused. But the explosion apparently occurred in a structure housing turbines near the No. 1 reactor at the plant rather than inside the reactor itself. The Nuclear and Industrial Safety Agency said serious damage to the containment core was unlikely despite the explosion.

Fears of a meltdown are being downplayed. In a seemingly contradictory statement, Naoto Sekimura, a professor at Tokyo University, told Japan’s public broadcaster NHK that "only a small portion of the fuel has been melted. But the plant is shut down already, and being cooled down. Most of the fuel is contained in the plant case, so I would like to ask people to be calm."

But according to the Fukushima Prefectural Government, hourly radiation emissions from the Fukushima plant reached 1,015 microsieverts on the premises—an amount equivalent to the dose an ordinary person would receive in one year. Iodine and cesium, two byproducts of the nuclear fission process, have been detected around the area. The Nuclear and Industrial Safety Agency rated the Fukushima accident at four on the International Nuclear Event Scale from 0 to 7, meaning an accident "with local consequences." The 1979 Three Mile Island accident in the US was rated five while the 1986 Chernobyl disaster in the USSR was a seven.

Residents within a 10-kilometer radius of the plant had been ordered to evacuate before the blast, up from an initial order to evacuate from a three-kilometer radius. Press accounts of the total number of evacuees range from 14,000 to 45,000. Thousands more have been evacuated from near a second plant, Fukushima Dai-ni, which also suffered damage to its cooling system. (NYT, AP, Radio Australia, ENS, Business Insider, March 12)

See our last posts on the Fukushima disaster.

Please leave a tip or answer the Exit Poll.