On the International Nuclear Event Scale, a Level 7 nuclear accident – a la Chernobyl, the worst in history – involves “widespread health and environmental effects” and the “external release of a significant fraction of the reactor core inventory.” Japan says that’s where it now stands.
While the country’s nuclear regulator announced yesterday that the total amount of radioactive materials released so far from the Fukushima Daiichi reactor equaled about 10 percent of that released in the Chernobyl disaster, an official from the plant’s operator said that the radiation released could eventually surpass levels seen in 1986. From the Times:
Japan’s previous rating of 5 placed the Fukushima accident at the same level as the Three Mile Island accident in Pennsylvania in 1979. Level 7 has been applied only to the disaster at Chernobyl, in Ukraine.
“This is an admission by the Japanese government that the amount of radiation released into the environment has reached a new order of magnitude,” said Tetsuo Iguchi, a professor in the department of quantum engineering at Nagoya University. “The fact that we have now confirmed the world’s second-ever Level 7 accident will have huge consequences for the global nuclear industry. It shows that current safety standards are woefully inadequate.”
Michael Friedlander, a former senior nuclear power plant operator for 13 years in the United States, said that the biggest surprise in the Japanese reassessment was that it took a month for public confirmation that so much radiation had been released.
Prime Minister Naoto Kan of Japan called in a nationally televised speech on Tuesday evening for Japan to rebuild. While taking note of the decision to raise the severity of the nuclear accident at Fukushima to the worst level on the international scale, he took pains to say that the reactors were being stabilized and to emphasize that releases of radioactive material are now declining.
See this useful graphic illustrating the radiation danger near and far from the plant, watch what happened when Vice went to Chernobyl, and consider the debate over the actual health impacts of that Ukrainian cataclysm.