Tokyo Electric Power Co. was aware 10-meter-plus tsunami could hit the Fukushima No. 1 nuclear power station as early as in 2008, reporting the results of simulations for the first time to the Nuclear and Industrial Safety Agency on March 7 — four days before 13-meter waves knocked out the plant, leading to three meltdowns, it was learned Wednesday.
The government and Tepco repeatedly had claimed they never imagined tsunami of such heights could hit the Fukushima plant.
But Tepco in fact conducted the simulations, from April to May 2008, assuming 10-meter-plus tsunami, officials of the utility said. The utility, however, never attempted to bolster the wave defenses of the Fukushima plant.
“That was only one of the research activities,” a Tepco official said, playing down the significance of the simulations.
Tepco conducted the simulations after the government revised quake resistance standards for nuclear plants in 2006.
The simulations were based on 10.2-meter-high tsunami hitting reactors 5 and 6 of the Fukushima plant, 9.3-meter waves hitting unit 2 and 8.7- to 8.4-meter waves hitting reactors 1, 3 and 4.
A Tepco section chief reported the results to NISA on March 7. NISA officials had pointed out “countermeasures are urgently needed,” calling for modifications.
The simulations assumed the occurence of an 8.2-magnitude quake hitting the ocean trench along the Tohoku region to the Boso Peninsula of Chiba Prefecture. The March 11 temblor was 9.0-magnitude.
“We need to examine how and what measures were taken” after the simulation results were submitted to NISA, said Yoshinori Moriyama, a senior NISA official in charge of measures against nuclear disasters.
8% of kids bolted
Fear of radiation prompted more than 70 percent of school transfers involving children in Fukushima Prefecture amid the nuclear crisis, a Kyodo News survey showed Wednesday.
The poll found that 17,651 children were transferred from preschools, elementary or junior high schools in Fukushima, representing 8 percent of about 210,000 such pupils in the prefecture as of May 2010.