Fukushima engineer says he helped cover up flaw at Dai-Ichi reactor no. 4

By Jason Clenfield, Bloomberg
22 Mar 2011

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. … 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.” For Tanaka, the nightmare intensified the next day when a series of explosions were triggered next to the reactor that he helped build. Since then, the risks of radioactive leaks increased as workers have struggled to bring the plant under control. …

Fukushima Engineer Says He Helped Cover Up Flaw at Dai-Ichi Reactor No. 4