TEPCO knew of tsunami danger in 2008

August 26, 2011

A top executive of TEPCO, as far back as June 2008, was informed by its own employees that a raging tsunami more than 10 meters in height could swamp its Fukushima No. 1 nuclear power plant, TEPCO said Aug. 25.

According to the Tokyo Electric Power Co., the utility requested that the Japan Society of Civil Engineers review methods of tsunami modeling. Before the request was filed, the results of a trial calculation were presented to Sakae Muto, then deputy general manager of TEPCO's Nuclear Power and Plant Siting Division in June 2008.

The tests showed that the Fukushima No. 1 plant could be hit by tsunami in excess of 10 meters, well above the height calculated in safety measures for the plant.

The modeling results were also given to Ichiro Takekuro, then TEPCO executive vice president, after the request was filed with the JSCE in October 2008.

In December 2008, TEPCO ran another trial using a different modeling method. The two sets of modeling results were presented to the Nuclear and Industrial Safety Agency on March 7 this year, four days before the March 11 magnitude-9.0 earthquake and deadly tsunami that crippled the plant northeast of Tokyo. The modeling results were not made public.

"Even tentative modeling results are a matter for evaluations, and they should have been reviewed by government panels," Yoshinori Moriyama, NISA's deputy director-general for nuclear accident measures, said at an Aug. 25 news conference. "TEPCO should have reported and published them earlier."

Junichi Matsumoto, acting general manager of TEPCO's Nuclear Power and Plant Siting Division, was also present at the same news conference.

"We did not publish the modeling results because they were based on a number of assumptions and were subject to uncertainties," he said. "We will think about (whether we will publish them in the future)."

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