By Steven Mufson
Washington Post Staff Writer
Tuesday, July 17, 2007
A small amount of water used to cool radioactive spent fuel rods at a Japanese nuclear reactor leaked into the Sea of Japan as a result of a massive earthquake that struck the country yesterday, though officials of Tokyo Electric Power insisted it posed no danger.
The leak took place at one of the seven units at the company's sprawling Kashiwazaki-Kariwa facility, the largest nuclear-power-producing site in the world. The unit, one of the two newest at the site, was designed by General Electric and is similar to about half of the reactors in the United States.
About 1.5 liters of slightly radioactive water spilled out of the cooling pool for spent fuel rods, leaked into another supply of water, and 315 gallons of that water were pumped into the sea, said Hiro Hasegawa, the manager of corporate communications at Tokyo Electric Power, by telephone.
Separately, a fire broke out at an electrical transformer at the site.
"This was a very, very small amount of water," said Hasegawa. "Even if it has some radiation, it doesn't have any impact on the atmosphere or the environment."
[The Associated Press reported that Tokyo Electric did not reveal the accident for hours after a 6.8 magnitude earthquake struck Japan's northwest coast.
[At least nine people were killed, and about 900 were injured as the earthquake toppled hundreds of wooden homes and tore 3-foot-wide fissures in the ground. Highways and bridges buckled, leaving officials struggling to get emergency supplies into the region.
[Some 10,000 people fled to evacuation centers as aftershocks rattled the area.]
Although the spill of cooling water at the electrical-generating plant was small, nuclear experts in the United States said the incident raised safety questions. It remained unclear how the cooling-pool water leaked out of its building if it spilled over the edge of the pool.
"It doesn't sound like it's such a big deal, but it is a leak and it makes you wonder whether the cooling pool is damaged," said Allison M. Macfarlane, professor of environmental science and policy at George Mason University.
Though Japanese nuclear plants, like U.S. plants, are built to withstand powerful earthquakes, Bloomberg News reported the unit had two cracks. But Hasegawa said the pool was no longer leaking and there was no hazard to the fuel rods. The cooling pool is 33 feet deep, and about 23 feet of water lies over the spent fuel rods.
Experts were cautious about accepting Tokyo Electric Power's assurances. Japan's nuclear power industry has a history of covering up incidents. In March, Tokyo Electric Power, Asia's biggest utility, said it would delay completion of two nuclear reactors after admitting that it covered up an accident in 1978. In 2002, the company shut all 17 of its reactors after admitting that employees had falsified nuclear safety documents since the late 1980s.
Safety concerns are one reason the company's plants have operated at less than 70 percent of capacity. At the time the quake hit yesterday, three of the seven units at Kashiwazaki-Kariwa were shut down for inspection. The other four units shut down automatically after the quake, the company said.
"Obviously something broke," said Michael Mariotte, executive director of the Nuclear Information and Resource Service. "The utility has not been very forthcoming in this incident."
Japan relies heavily on its 55 nuclear power plants. The government has set a target of building enough nuclear plants to keep nuclear's share of total electricity in Japan between 30 and 40 percent.