One of the reactors in the crippled Fukushima nuclear plant may have been relying on flawed steel to hold the radiation in its core, according to an engineer who helped build its containment vessel four decades ago.
Mitsuhiko Tanaka says he helped conceal a manufacturing defect in the $250 million steel vessel installed at the Fukushima Dai-Ichi No. 4 reactor while working for a unit of Hitachi Ltd. (6501) in 1974. The reactor, which Tanaka has called a “time bomb,” was shut for maintenance when the March 11 earthquake triggered a 7-meter (23-foot) tsunami that disabled cooling systems at the plant, leading to explosions and radiation leaks.
“Who knows what would have happened if that reactor had been running?” Tanaka, who turned his back on the nuclear industry after the Chernobyl disaster, said in an interview last week. “I have no idea if it could withstand an earthquake like this. It’s got a faulty reactor inside.”
Tanaka’s allegations, which he says he brought to the attention of Japan’s Trade Ministry in 1988 and chronicled in a book two years later called “Why Nuclear Power is Dangerous,” have resurfaced after Japan’s worst nuclear accident on record. The No. 4 reactor was hit by explosions and a fire that spread from adjacent units as the crisis deepened.
No Safety Problem
Hitachi spokesman Yuichi Izumisawa said the company met with Tanaka in 1988 to discuss the work he did to fix a dent in the vessel and concluded there was no safety problem. “We have not revised our view since then,” Izumisawa said.
Kenta Takahashi, an official at the Trade Ministry’s Nuclear and Industrial Safety Agency, said he couldn’t confirm whether the agency’s predecessor, the Agency for Natural Resources and Energy, had conducted an investigation into Tanaka’s claims. Naoki Tsunoda, a spokesman at Tokyo Electric Power Co., which owns the plant, said he couldn’t immediately comment.
Tanaka, who said he led the team that built the steel vessel, was at his apartment on Tokyo’s outskirts when Japan’s biggest earthquake on record struck off the coast on March 11, shaking buildings in the nation’s capital.
“I grabbed my wife and we just hugged,” he said. “I thought this is it: we’re dead.”
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