CONTROVERSES ENER...ETHIQUES
et NUCLEAIRES
SEISMES ET ENERGIE NUCLEAIRE
JAPON, le 16 juillet 2007
Japan closes nuclear plant damaged by earthquake
Sources Sortir du nucléaire, http://www.iht.com/
July 17, 2007
By Martin Fackler

     TOKYO: The Japanese authorities on Tuesday shut down a nuclear power plant after a radiation leak and other damage from an earthquake in the nation's northwest raised new concerns about the safety of Japan's nuclear industry.
     Tokyo Electric Power, which operates the nuclear plant near the city of Kashiwazaki, said it had found more than 50 problems had been caused by the earthquake Monday. Most were minor, but the most serious involved 100 drums of radioactive waste that fell over. The lids on some of them opened, the company said, and the contents spilled out.
     The earthquake, the first of two that struck Japan on Monday - one with the same intensity rattled the sea off Kyoto - also caused a small fire at the plant and the leakage of 317 gallons of water containing trace levels of radioactive materials into the Sea of Japan, the company said.
     The company announced Tuesday that it had detected tiny amounts of radioactive material in an air filter in one of the plant's seven reactors, but the company said it was unlikely that the material had entered the atmosphere.
     The company said it was examining how the tainted water got out, but said the levels of radioactivity were too low to endanger humans or the environment.
     Prime Minister Shinzo Abe criticized Tokyo Electric for being "too slow" in reporting the problems to the government and the public.
     "Nuclear power can only operate with the people's trust," Abe said. Power companies "must accurately and swiftly report what is happening."
     Television footage showed rescuers digging through buildings in Kashiwazaki that were toppled by the earthquake, which local police said killed at least nine people and injured another 1,000. Japan's meteorological agency said the earthquake measured 6.8 on the Richter Scale, while the United States Geological Survey put it at 6.6.
     Japan's military used warships and trucks to carry rice balls, bread and water to the remote region in Niigata Prefecture, about 255 kilometers, or 160 miles, northwest of Tokyo. But the relief efforts were slowed by landslides and gaping cracks in the earth that severed rail lines and roads, media reports said.
     About 13,000 residents fled their homes, the news media reported. TV footage showed many sleeping on blankets and futons in school gymnasiums that had been turned into makeshift shelters.
     In Tokyo, government ministers scrambled to reassure the public about the safety of the nation's nuclear power plants, which have suffered a string of accidents in recent years. The Economic Ministry, which regulates the power industry, moved swiftly to reprimand Tokyo Electric for failing to report the leak to authorities for six hours. The ministry also ordered the plant's operations shut down until safety could be ensured and dispatched a team of inspectors to survey the damage.

      Nuclear-safety problems can be a particularly sensitive issue in Japan, the only nation to be attacked with atomic weapons, in Hiroshima and Nagasaki in 1945. Safety experts said the authorities apparently feared the accidents Monday could raise new doubts about the 55 nuclear reactors that Japan relies on for about a third of its electricity and to lessen oil dependence on the Middle East.
     "This will stir new debate about whether nuclear plants are safe enough," said Haruki Madarame, a professor in nuclear-safety engineering at Tokyo University. "Authorities will have to show the public that they are taking all reasonable steps to ensure safety."
     Japan is one of the most earthquake-prone nations in the world and has strict regulations meant to prevent earthquake damage to its nuclear plants. Those include building nuclear plants on solid bedrock to limit shaking from earthquakes and erecting anti-tsunami walls at plants along the coast, like the Kashiwazaki plant.
     Tokyo Electric said the damage from the earthquake did not threaten the safety of the reactors at the Kashiwazaki plant, the world's largest by amount of electricity produced. Four reactors were operating at the time, and all shut down safely, Tokyo Electric said.
     But the power company said a cause of the damage was that the force of the shaking from the earthquake had exceeded the design limits of the reactors, suggesting that the plant's builders had underestimated the strength of possible earthquakes in the region.
     The chief government spokesman, Yasuhisa Shiozaki, said the designs of other nuclear plants may also have to be re-examined after earthquake to make sure they are strong enough to resist all potential earthquakes.
     Japan needs "a careful analysis of how far" the earthquake exceeded estimates "to determine whether there is any new knowledge to be learned," Shiozaki said.
     Safety experts said Monday's earthquake struck as power companies were examining reactors to see if they met new safety standards enacted in September. They said the unexpected strength of the earthquake's tremors could force the authorities to set even tougher standards and carry out new seismic studies to determine if they were underestimating the size of potential earthquakes.
     The closure of the Kashiwazaki plant, which can produce up to 7,219 megawatts, came as Tokyo prepared for peak power use during the summer months.
     In March, another nuclear plant operator, Hokuriku Electric Power, shut down a reactor after admitting it had covered up a 15-minute uncontrollable nuclear chain reaction in 1999. Three years ago, Japan's deadliest nuclear accident killed four workers at a nuclear plant when a steam pipe burst.