TOKYO—Japanese engineers conceded on Friday that burying a crippled nuclear reactor in sand and concrete may be the only way to prevent a catastrophic radiation leak, as Japan raised the Fukushima crisis to level 5, putting it at par with the Three Mile Island accident, the second biggest nuclear disaster in history.
Entombing the stricken Japanese reactors in sand and concrete would replicate the method used to seal huge leakages from Chernobyl in 1986, considered the worst in history.
It was the first time the Japanese nuclear facility operator had acknowledged that burying the sprawling complex was an option, a sign that piecemeal actions, such as dumping water from military helicopters, were having little success.
“It is not impossible to encase the reactors in concrete. But our priority right now is to try and cool them down first,” an official from the plant operator, Tokyo Electric Power Co., told a news conference.
Japan’s nuclear safety agency raised the crisis level at the Fukushima Daiichi facility to 5 from 4 on the international scale of gravity for atomic accidents, which goes to as high as 7.
France’s Nuclear Safety Authority rates the Fukushima crisis at 6 on the scale. The Chernobyl disaster is at 7, the highest.
Level 4 means there has been an “accident with local consequences.”
The decision by the Nuclear and Industrial Safety Agency (Nisa) puts Fukushima on the same level as the 1979 accident at Three Mile Island in Pennsylvania and makes it the worst ever in Japan.
Cooling function lost
A spokesperson for Nisa said it had alerted the International Atomic Energy Agency (IAEA) on its decision, which was made due to the condition of reactors 1, 2 and 3 at the plant stricken by last week’s massive earthquake and tsunami.
“The cooling function was lost and the reactor cores were damaged. Radioactive particles continue to be released in the environment,” he said.
Among the six reactors at the power plant, reactors 1, 2 and 3 were operating at the time of the quake and halted automatically.
But the cores are believed to have partially melted because the twin disasters knocked out the plant’s reactor cooling systems, sparking a series of explosions and fires.
Authorities have since struggled to keep fuel rods inside reactors and fuel storage containment pools under water. If they are exposed to air, they could degrade further and emit large amounts of dangerous radioactive material.
Three Mile Island, Chernobyl
The March 28, 1979, accident at Three Mile Island was a partial reactor meltdown that led to “very small” releases of radioactivity. It caused no casualties, but was rated 5, corresponding to “an accident with wider consequences.” Level 6 is a “serious accident.”
The April 26, 1986, explosion at the Soviet nuclear power plant in Chernobyl was the world’s worst atomic accident.
It spewed radioactive dust over swathes of Ukraine, Belarus, Russia and western Europe. Estimates of the death toll ranged from the UN figure of 4,000 to tens or even hundreds of thousands, proposed by nongovernmental groups.
The reclassification did not appear to signal that the crisis had grown more severe, only that officials felt it needed to be upgraded.
Japan overwhelmed
Chief Cabinet Secretary Yukio Edano acknowledged on Friday that the government was overwhelmed by the scale of last week’s twin disasters.
Nuclear experts have been saying for days that Japan had been underplaying the severity of the crisis.
“The unprecedented scale of the earthquake and tsunami that struck Japan, frankly speaking, were among many things that happened that had not been anticipated under our disaster management contingency plans,” Edano said, admitting that information had not been shared quickly enough.
“In hindsight we could have moved a little quicker in assessing the situation and coordinating all that information and provided it faster,” he said.
Almost 17,000 dead, missing
The number of confirmed dead in the earthquake and tsunami has hit 6,539, surpassing the toll from the massive tremor in Kobe in 1995, police said.
The number of unaccounted for rose to 10,354, putting the combined total of dead and missing at 16,893. A total of 2,513 people were injured.
The chances of finding more survivors have dwindled.
Fear of radiation
Millions in Tokyo remained indoors on Friday, fearing a blast of radioactive material from the nuclear complex, 240 kilometers to the north, although prevailing winds would likely carry contaminated smoke or steam away from the densely populated city to dissipate over the Pacific Ocean.
Radiation did not pose an immediate risk to human health outside the vicinity of the plant, said Michael O’Leary, the World Health Organization’s representative in China.
President Barack Obama, who stressed the United States did not expect harmful radiation to reach its shores, said he had ordered a comprehensive review of domestic nuclear plants and pledged Washington’s support for Japan.
The Group of Seven rich nations, stepping in together to calm global financial markets after a tumultuous week, agreed to join in rare concerted intervention to restrain a soaring yen.
History of secrecy
The Japanese government has been slow in releasing information on the crisis, even as the troubles have multiplied. In a country where the nuclear industry has a long history of hiding its safety problems, this has left many people—in Japan and among governments overseas—confused and anxious.
At times, Japan and the United States—two very close allies—have offered starkly differing assessments over the dangers at the Fukushima plant.
Tokyo said on Friday it was asking Washington for help.
A US military fire truck was used to help spray water into the crippled Unit 3 at Fukushima. The US vehicle was used alongside six Japanese military fire trucks.
The fire trucks allowed emergency workers to stay a relatively safe distance from the radiation, firing the water with high-pressure cannons.
Cooling may take weeks
The US Nuclear Regulatory Commission said it could take weeks to reverse the overheating of fuel rods at Fukushima.
The Vienna-based IAEA said the radiation level at the plant was as high as 20 millisieverts per hour. The limit for the workers was 100 per hour.
At its worst, radiation in Tokyo has reached 0.809 microsieverts per hour this week, 10 times below what a person would receive if exposed to a dental X-ray.
More than 452,000 people made homeless by the quake and tsunami were staying in schools and other shelters, as supplies of fuel, medicine and other necessities ran short.
About 343,000 Japanese households still do not have electricity, and about 1 million have no water. Reports from Reuters, AFP and AP