Bloomberg
(Updates with comment from Tepco in third paragraph.)
By Yuji Okada and Aaron Sheldrick
April 12 (Bloomberg) -- 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 today raised
the rating to 7. The accident at the Fukushima Dai-Ichi station
was previously rated 5 on the global scale, the same as the 1979
partial reactor meltdown at Three Mile Island in Pennsylvania.
The stricken nuclear plant, located 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. Tokyo Electric Power Co. said its plant,
which has withstood hundreds of aftershocks, may spew more
radiation than Chernobyl before the crisis is contained.
“The radiation leaks haven’t stopped,” Junichi Matsumoto,
general manager of the utility’s nuclear power and plant fitting
division, said in Tokyo today. “If the leaks continue, the
total radiation from the reactors may exceed” that from
Chernobyl.
The radiation released so far from the Fukushima accident
is estimated to be around 10 percent of that from Chernobyl,
Japan’s nuclear safety agency said earlier.
Today’s rating change won’t lead to a further widening of
the evacuation zone beyond the increase announced yesterday,
Kenkichi Hirose, an adviser to Prime Minister Naoto Kan’s
cabinet, said at the nuclear agency’s news conference.
Evacuation Zone
Chief Cabinet Secretary Yukio Edano said yesterday 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
today. “The assessment level of 7 may be the same, but in terms
of its shape and contents, the process has been different."
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 times increase in the severity of the incident
or accident, according to the INES factsheet.
Levels 1 through 3 are classified as incidents and those
from 4 to 7 are defined as accidents. Level 7 means there has
been a ‘‘major release of radioactive material with widespread
health and environmental effects requiring implementation of
planned and extended countermeasures,’’ the factsheet says.
‘Beginning to Wake Up’
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 level 7 assessment is based on the combined severity of
the situation at reactor Nos. 1, 2 and 3.,Hidehiko Nishiyama,
deputy director-general of the nuclear safety agency, said
today.
‘‘Most radioactive substances detected around the plants
were probably released from explosions that happened at the
early stages of the crisis,’’ Kazuhiko Kudo, research professor
of nuclear engineering at Kyushu University, said before the
announcement.