TOKYO — A Japanese government agency that spent several years evaluating the Fukushima Daiichi nuclear plant declared the facility safe after dismissing concerns from a member of its own expert panel that a tsunami could jeopardize its reactors.
Yukinobu Okamura, a prominent seismologist, warned of a debilitating tsunami in June 2009 at one of a series of meetings held by the Nuclear and Industrial Safety Agency to evaluate the readiness of Daiichi, as well as Japan’s 16 other nuclear power plants, to withstand a massive natural disaster. But in the discussion about Daiichi, Okamura was rebuffed by an executive from Tokyo Electric Power Co., which operates the plant, because the utility and the government believed earthquakes posed a greater threat.
That conclusion left Daiichi vulnerable to what unfolded March 11, when a 9.0-magnitude earthquake struck off Japan’s northeast coast.
Experts now say that Daiichi, as designed, withstood the quake. It was the ensuing tsunami, more than 20 feet high, that knocked out the facility’s critical backup power supply and triggered a nuclear emergency, resulting in widespread releases of radiation.
The disaster highlights the government’s miscalculation in prioritizing one natural disaster over another and casts scrutiny on a review that more often re affirmed NISA’s and TEPCO’s standards than challenged them.
“Now I regret that I didn’t stress this more strongly, to push them to research this,” said Okamura, a director at a government-funded research institution.
