August 25, 2011
Tokyo Electric Power Company (TEPCO) on August 24 made public that it neglected to improve disaster preventive measures at its Fukushima Daiichi nuclear power plant despite having recognized the possibility that a nearly 16-meter tsunami could threaten the plant.
In 2002, TEPCO began doing trial calculations in order to judge the height of tsunami waves that might hit the Fukushima NPP if a massive earthquake occurred in the waters off Fukushima Prefecture.
As a result of the calculations, TEPCO in 2008 found that a magnitude 8.3 quake in the waters off Fukushima, similar to the 1986 earthquake off the coast of Iwate Prefecture, would cause 8.4- to 15.7-meter tsunamis and that these tsunamis would likely strike the Fukushima Daiichi and Daini NPPs.
Although TEPCO knew that the Fukushima power plant was only prepared for an up to 5.7-meter tsunami, it did nothing. The reason for this, the company said that it needed to examine the accuracy of the calculation results.
Furthermore, it was only four days before the March 11 disaster that the electric company submitted the results to the Nuclear and Industrial Safety Agency.
TEPCO claims that the main cause of the Fukushima nuclear accident was the power shutdown caused by the disaster resultant tsunami.
The actual height of tsunami waves that reached the Fukushima NPPs was 13.1 meters at Fukushima Daiichi and 9.1 meters at Fukushima Daini.
If TEPCO had taken prompt and proper measures against tsunamis at the time it obtained the results, it may well have averted a great deal of the damage that occurred.