Japan raised the severity rating of its nuclear crisis to the highest, matching the 1986 Chernobyl disaster, after increasing radiation prompted the government to widen the evacuation zone and aftershocks rocked the country.
Japan’s Nuclear and Industrial Safety Agency yesterday raised the rating to 7. The accident at the Fukushima Dai-Ichi plant previously was rated a 5 on the global scale, the same as the 1979 partial meltdown at Three Mile Island in Pennsylvania.
The stricken plant, about 220 kilometers (135 miles) north of Tokyo, is leaking radiation in Japan’s worst civilian nuclear disaster after a magnitude-9 quake and tsunami on March 11. The station, which has withstood hundreds of aftershocks, may spew more contamination than Chernobyl before the crisis is contained, operator Tokyo Electric Power Co. said.
Fukushima has so far released about 10 percent as much radiation as Chernobyl, Japan’s nuclear safety agency said in a statement. The leaks won’t be stopped in “a few days or weeks,” Chief Cabinet Secretary Yukio Edano said.
U.S. stocks fell after Japan’s announcement, giving the Standard & Poor’s 500 Index the longest losing streak since November. The benchmark for American stocks has fallen for four consecutive days, retreating 0.7 percent to 1,315.37 at 9:32 a.m. in New York.
‘Will Do Our Best’
“We are trying to resolve the situation as soon as possible and will do our best to cool down the reactors and prevent the spread of radioactive substances,” Masataka Shimizu, president of the utility, said in a statement after the rating was raised. He also apologized for the accident.
The company’s shares fell 10 percent to close at 450 yen Tokyo yesterday. The stock has slumped 79 percent since the crisis began.
Prime Minister Naoto Kan said he has asked Tepco, as the utility is called, to give an assessment of when the company expects to resolve the crisis. “An outlook will be presented soon,” he said at news conference in Tokyo.
Edano said April 11 that residents of some towns beyond the 20-kilometer evacuation zone around the plant will have a month to move to safer areas.
“In contrast with Chernobyl, we have been able to avoid direct health risks,” Edano said at a public event in Tokyo. “The assessment level of 7 may be the same, but in terms of its shape and contents, the process has been different.”
The disaster in Ukraine spewed debris as high as 9 kilometers into the air and released radiation 200 times the volume of the combined bombings of Hiroshima and Nagasaki in 1945, according to a 2006 report commissioned by Europe’s Green Party.
Fewer people have been exposed to high levels of radiation from Fukushima than Chernobyl, said Richard Wakeford, a professor at the Dalton Nuclear Institute at the University of Manchester in the U.K. “The important thing is monitoring and protecting people on the ground,” Wakeford said by telephone.
The International Nuclear and Radiological Event Scale rates nuclear accidents in terms of their effects on health and the environment, according to the International Atomic Energy Agency, which helped set up the system. Each of its seven steps represents a ten-fold increase in severity.
A 7 rating means there has been a “major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures,” according to the INES factsheet.
‘Beginning to Wake Up’
The assessment is based on the combined severity of the situation at reactor Nos. 1, 2 and 3, said Hidehiko Nishiyama, deputy director-general of the Nuclear and Industrial Safety Agency, or NISA.
The government “is at last beginning to wake up to the reality of the scale of the disaster,” said Philip White, International Liaison Officer at the Citizens’ Nuclear Information Center, a Tokyo-based group opposed to atomic energy. “Its belated move to evacuate people from a larger area around the nuclear plant, likewise, is a recognition that the impact on public health is potentially much greater than it first acknowledged.”
The March 11 earthquake, the nation’s strongest on record, and tsunami left about 27,500 dead or missing, according to Japan’s National Police Agency.
Japan was struck by two earthquakes stronger than magnitude 6 yesterday, hindering recovery efforts as workers were temporarily evacuated. The temblors followed a 6.6-magnitude quake April 11 and a magnitude 7.1 aftershock on April 7.
While there was no damage to the Fukushima plant from the recent earthquakes, disruptions make it difficult to assess when it will achieve cold shutdown of the three damaged reactors, said Junichi Matsumoto, general manager of one of Tokyo Electric Power Co.’s nuclear divisions. The station has six reactors.