TOKYO — Just a month before a powerful earthquake and tsunami crippled the Fukushima Daiichi plant at the center of Japan’s nuclear crisis, government regulators approved a 10-year extension for the oldest of the six reactors at the power station despite warnings about its safety.
The committee reviewing extensions pointed to stress cracks in the backup diesel-powered engines at Reactor No. 1 at the Daiichi plant, according to a summary of its deliberations that was posted on the Web site of Japan’s nuclear regulatory agency after each meeting. The cracks made the engines vulnerable to corrosion from seawater and rainwater. The engines are thought to have been knocked out by the tsunami, shutting down the reactor’s vital cooling system.
The Tokyo Electric Power Company, which runs the plant, has since struggled to keep the reactor and spent fuel pool from overheating and emitting radioactive materials.
Several weeks after the extension was granted, the company admitted that it had failed to inspect 33 pieces of equipment related to the cooling systems, including water pumps and diesel generators, at the power station’s six reactors, according to findings published on the agency’s Web site shortly before the earthquake.
Regulators said that “maintenance management was inadequate” and that the “quality of inspection was insufficient.”
Less than two weeks later, the earthquake and tsunami set off the crisis at the power station.
The decision to extend the reactor’s life, and the inspection failures at all six reactors, highlight what critics describe as unhealthy ties between power plant operators and the Japanese regulators that oversee them. Expert panels like the one that recommended the extension are drawn mostly from academia to backstop bureaucratic decision-making and rarely challenge the agencies that hire them.
Because public opposition to nuclear power makes it hard to build new power plants, nuclear operators are lobbying to extend their reactors’ use beyond the 40-year statutory limit, despite uneven safety records and a history of cover-ups. The government, eager to expand the use of nuclear energy and reduce the reliance on imported fossil fuels, has been largely sympathetic. Such extensions are also part of a global trend in which aging plants have been granted longer lives.
Over the next decade in Japan, 13 more reactors — and the other 5 at the Fukushima Daiichi plant — will also turn 40, raising the prospect of gargantuan replacement costs. That is one reason critics contend that the Nuclear and Industrial Safety Agency’s committee in charge of inspecting aging nuclear power plants may play down its own findings.
In approving the extension in early February, regulators told Tokyo Electric to monitor potential damage from radiation to the reactor’s pressure vessel, which holds fuel rods; corrosion of the spray heads used to douse the suppression chamber; corrosion of key bolts at the reactor; and conduction problems in a gauge that measures the flow of water into the reactor, according to a report published in early February.
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