The Nuclear and Industrial Safety Agency (NISA) said Saturday afternoon the explosion at the Fukushima No. 1 nuclear plant could only have been caused by a meltdown of the reactor core.
Cesium and iodine, by-products of nuclear fission, were detected around the plant, which would make the explosion the worst accident in the roughly 50-year history of Japanese nuclear power generation. Nikkei.
Read Beyond Nuclear board member, Karl Grossman's explanation on Common Dreams.
According to reports, a seriously injured worker was trapped within Fukushima Daiichi unit 1 in the crane operating console of the exhaust stack and is now confirmed to have died. Four workers were injured by the explosion at the same reactor and have been taken to hospital. A contractor was found unconscious and taken to hospital. Two workers of a 'cooperative firm' were injured, said Tepco; one with a broken bone. At Fukushima Daiini unit 3 one worker received a radiation dose of 106 mSv. However, given the high levels of radiation inside the plant, and the opacity of information about what has actually gotten out, it is difficult to speculate at present on the true extent of radioactive contamination in the immediate and surrounding areas near the plant.
The Guardian is reporting that a Japanese seismologist Ishibashi Katsuhiko, warned long ago about the risks it faced in building nuclear plants in areas of intense seismic activity. Katsuhiko stated in 2007, specifically, that such an accident was highly likely to occur. Nuclear power plants in Japan have a "fundamental vulnerability" to major earthquakes. The government, the power industry and the academic community had seriously underestimated the potential risks posed by major quakes.
March 12, 2011