Damaged Japanese nuclear plant found to sit on fault line

Published 19 July 2007

World’s largest nuclear power plant shut down indefinitely after 6.5 magnitude causes radioactive spillage; future of Japan’s nuclear industry uncertain

This is not what the Japanese wanted to hear: The world’s biggest nuclear power station faces an uncertain future after it emerged yesterday that it may lie directly above the fault line that triggered this week’s earthquake in which nine people died and more than 1,000 were injured. The Kashiwazaki-Kariwa plant — the biggest in the world in terms of output capacity — has been shut down indefinitely after it shook violently when an earthquake measuring 6.8 on the Richter scale struck Niigata prefecture in northern Japan on Monday. The plant was not designed to resist shaking caused by earthquakes of greater than magnitude 6.5.

The Guardian’s Justin McCurry reports that the Tokyo Electric Power company (Tepco), which operates the plant, said the amount of radioactivity in water that leaked into the sea during the earthquake was 50 percent higher than it originally said. The firm blamed a calculation error and said the levels were still well within safety standards. It also said that 400 drums of low-level radioactive waste — not 100 originally reported — had toppled over during the quake. About 40 lost their lids, spilling their contents on to the ground. The spillage was one of more than 50 malfunctions the plant experienced in the immediate aftermath of the quake. International nuclear inspectors said they were concerned by Tepco’s apparent lack of preparedness for such a powerful earthquake.

The mayor of Kashiwazaki, Hiroshi Aida, ordered Tepco to close the plant indefinitely until its safety could be assured. The closure has forced the firm to ask six other power utilities to supply it with additional electricity until end of September to avoid power cuts when demand peaks later this summer.

Tepco is under pressure to explain why it took so long to inform the authorities of radioactive leaks and why only four employees were on hand to tackle a fire inside an electrical transformer that was only extinguished after firefighters arrived almost 90 minutes later. The mishaps have raised questions about the wisdom of building nuclear power stations in a country where earth tremors are recorded, on average, every few minutes. New safety regulations were brought in last year, but upgrading ageing reactors so that they can withstand tremors of a greater magnitude than 6.5 will require a huge investment. Akira Fukushima, the deputy director general of Japan’s Nuclear and Industrial Safety Agency, said no irregularities had been found in critical areas of the plant, but added: “It is possible that the epicentre fault line does run beneath the power plant. Our decision on what to do in the future will depend on the report we get from Tepco.” Inspectors reportedly identified four fault lines in the area while conducting a geological survey before work began on the Kashiwazaki plant in 1980 but concluded that they were inactive, according to the Asahi newspaper.

Japan has very few indigenous energy sources and it depends on 55 nuclear plants for 30 percent of its electricity. Despite several accidents and mounting public opposition to nuclear power, it plans to increase capacity to 40 percent by the end of the decade. Only France and the United States have more nuclear power stations than Japan, where the first plant went into service in 1966. Japan’s 55 plants have a total generating capacity of 49,470 megawatts, supplying just under a third of the country’s electric power output.