Kan Slams Tepco's Tsunami Defenses, Offers Assurances Over Radiation Leaks
Japan’s Prime Minister Naoto Kan. Photographer: Haruyoshi Yamaguchi/Bloomberg
Japan’s Prime Minister Naoto Kan said that a damaged nuclear plant’s tsunami defenses were inadequate, while reassuring the public that radiation leaks pose no health threat beyond an evacuation zone.
Tokyo Electric Power Co.’s sea wall, designed to withstand a 5.5-meter (18-foot) wave, was breached by a surge estimated by the government to be almost three times higher following a magnitude-9 earthquake on March 11. Back-up diesel generators for cooling systems, which might have prevented the nuclear disaster, were positioned in a basement swamped by the wave.
“It’s undeniable their assumptions about tsunamis were greatly mistaken,” Kan said in parliament. “The fact that their standards were too low invited the current situation.”
There is no danger of contamination outside the 20- kilometer (12.4-mile) exclusion zone imposed around the Fukushima Dai-Ichi plant, he said.
Plutonium traces found in soil pose no threat to workers on site or people close by, Hidehiko Nishiyama, a spokesman at the Japan Nuclear and Industrial Safety Agency, said in Tokyo yesterday. Radioactive water on the floor of turbine buildings at the No. 2 and No. 3 reactors will be drained and stored in tanks on site, he said.
“Plutonium can’t really travel by air, but we have to be careful about water,” said Tetsuo Iguchi, a professor specializing in isotope analysis and radiation detection at Nagoya University in central Japan.
Water Hazard
Water in a tunnel outside the No. 2 reactor emitted radiation exceeding 1 sievert an hour, a Tokyo Electric spokesman said. Exposure to that dose for 30 minutes would trigger nausea and four hours might lead to death within two months, according to the U.S. Environmental Protection Agency. A person standing 1 kilometer away would receive a dose 1 million times smaller, Iguchi said.
“Workers can’t work near water with radiation levels exceeding 1 sievert per hour, at least not within a few meters,” said Hironobu Unesaki, a professor at Kyoto University’s Research Reactor Institute. “They may need to remotely remove water or rotate workers for very short periods of time.”
Higher readings inside and outside the No. 2 unit indicate that a partial meltdown of fuel rods is “pretty much without a doubt,” Chief Cabinet Secretary Yukio Edano said yesterday. “This is a grave situation.”
The leakage of plutonium is another sign of such damage, Nishiyama said.
‘Puff Releases’
“If you have any damage to the fuel, you are likely to be spreading some of that around,” said Kathryn Higley, a radiation health physicist at Oregon State University in Corvallis, who has worked on reactors and inspected nuclear power plants for emergency preparedness. “As they start getting in there to try to remove the liquid, you’re probably going to see some localized spreading of contamination and maybe some puff releases.”
Sheep grazed in parts of the U.K. and Scandinavia contaminated by radioactive cesium from the 1986 Chernobyl reactor meltdown and fire are still routinely tested before they’re sold for slaughter, Higley said.
International Help
Cleanup probably will take at least five years because of the time needed for radioactivity to diminish so experts can assess the damage, Akira Tokuhiro, a professor of mechanical and nuclear engineering at the University of Idaho, said in an interview. That assessment will determine whether the reactors should be entombed or dismantled to eliminate any further radiation risk, he said.
“It will need international intervention, perhaps by the United Nations or the International Energy Agency,” to assure lessons of the disaster are learned by other nuclear operators, Tokuhiro said.
The plant “continues to further stabilize,” Bill Borchardt, the executive director for operations at the U.S. Nuclear Regulatory Commission, said during a briefing for the Senate Energy and Natural Resources Committee in Washington.
The number of dead and missing from the earthquake and tsunami had reached 27,575 as of 9 p.m. yesterday, Japan’s National Police Agency said.
To contact the reporters on this story: Takashi Hirokawa in Tokyo at thirokawa@bloomberg.net; Yuriy Humber in Tokyo at yhumber@bloomberg.net; Sachiko Sakamaki in Tokyo at ssakamaki1@bloomberg.net
To contact the editor responsible for this story: Patrick Chu at pachu@bloomberg.net
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