Is Nuclear Power Losing Steam In Japan?

For Tokyo's confident corps of nuclear regulators, a "systems failure" is something that happens in far-off places such as Three Mile Island and Chernobyl, not in western Japan. So last month, when nearly 70 tons of radioactive coolant gushed through a cracked pipe at Kansai Electric Power Co.'s Mihama No. 2 nuclear reactor and radiation leaked out, they were taken aback. For weeks, they downplayed the accident, preferring to call it "an incident."

Now, the lid is off, and there is growing evidence that Japan's problems are more widespread. If so, besides costing millions to fix, that could throw cold water on Japan's nuclear-energy program. The Mihama No. 2 reactor was built in 1972 by Mitsubishi Heavy Industries Ltd., using technology licensed from Westinghouse Electric Corp. If it's a design problem, that could spell trouble for eight other nuclear reactors across Japan built with the same technology.

Already, the accident is providing fuel for the antinuclear movement. Just last summer, Tokyo's Ministry of International Trade & Industry announced a plan to increase Japan's reliance on nuclear power from 30% of electricity needs now to 43% in 20 years. The antinuclear movement was beginning to lose steam as the gulf war reminded consumers of their dependence on oil. Now, activists are crying cover-up at Mihama. "I clearly say they are lying," says Jinzaburo Takagi, a nuclear chemist and head of the Citizen's Nuclear Information Center. "The data show that it was dangerously close to a meltdown."

While Kansai Electric won't comment until its investigation is complete, analysts suspect that either corrosion or excessive vibration helped crack a 25-foot tube. Two valves failed to open, preventing emergency cooling water from entering. A backup spray system did cool off the core, and the reactor was shut down. But on Mar. 1, Kansai Electric revealed that radioactive steam had seeped out for seven minutes before a worker manually shut a third faulty valve.

NEW BLUEPRINT. Westinghouse, which built Mihama's 340-megawatt No. 1 reactor in 1970, says Mitsubishi altered the design when it built the more powerful 500-megawatt No. 2 reactor. "There's no fundamental flaw in the design," says Jon R. Elmendorf, president of Westinghouse Energy Systems-Japan Inc. Yet after a series of tube failures at U. S. plants, Westinghouse in the late 1970s changed its design, switching from carbon steel supports to more durable stainless steel.

Since Mihama, there have been three less serious accidents. A special committee is now reviewing existing regulations. MITI has already tightened its rules on when to shut down a reactor. Japan once prided itself on having one-tenth the U. S. shutdown rate, but "overnight, that confidence was destroyed," admits Kazumasa Kusaka, MITI's director of nuclear energy. MITI plans to spend $27 million on a nuclear awareness campaign, but after Mihama, many Japanese think they are aware enough.