Japan’s Reactor Risk Foretold 20 Years Ago in U.S. Agency Report

The earthquake disaster at the Fukushima nuclear power plant north of Tokyo was foretold in a report published two decades ago by a U.S. regulatory agency.

In a 1990 report, the U.S. Nuclear Regulatory Commission, an independent agency responsible for ensuring the safety of the country’s power plants, identified earthquake-induced diesel generator failure and power outage leading to failure of cooling systems as one of the “most likely causes” of nuclear accidents from an external event.

While the report was cited in a 2004 statement by Japan’s Nuclear and Industrial Safety Agency, adequate measures to address the risk were not taken by Tokyo Electric Power Co., which operates the plant in Fukushima prefecture, said Jun Tateno, a former researcher at the Japan Atomic Energy Agency and professor at Chuo University.

“It’s questionable whether Tokyo Electric really studied the risks outlined in the report,” Tateno said in an interview. “That they weren’t prepared for a once in a thousand year occurrence will not go over as an acceptable excuse.”

Hajime Motojuku, a spokesman for Tokyo Electric, said today he couldn’t immediately confirm whether or not the company was aware of the report.

The 40-year-old Fukushima plant was hit by Japan’s strongest earthquake on record March 11 only to have its power and cooling systems knocked out by the 7-meter (23-foot) tsunami that followed.

Radioactive Steam

Lacking power to cool reactors, engineers vented radioactive steam to release pressure, leading to as many as four explosions that blew out containment walls at the plant 135 miles (220 kilometers) north of the capital.

While the appropriate measures that should have been implemented are still to be evaluated, more extensive waterproofing of the underground portion of the reactor could have helped prevent the cooling systems’ failure, said Tateno, who questions the use of nuclear power in Japan because of its seismic activity.

Engineering of the Fukushima Dai-Ichi nuclear plant or its age are unlikely causes of the problem, said Tateno, author of a book titled “The Coming Age of Scrapping Nuclear Plants.”

While nuclear power has been supported as a way of producing vast quantities of energy compared with other sources, “it will be difficult to get any more nuclear plants built going forward” in Japan, Tateno said.

To contact the reporters on this story: Makiko Kitamura in Tokyo at mkitamura1@bloomberg.net; Maki Shiraki in Tokyo at mshiraki1@bloomberg.net

To contact the editor responsible for this story: Peter Langan at plangan@bloomberg.net

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