The operator of Japan’s ruined Fukushima Daiichi nuclear power plant was aware of the need to improve the facility’s defences against tsunami more than two years before the March 2011 disaster but failed to take action, according to an internal company document.
The revelation casts doubt on claims by Tokyo Electric Power (Tepco) that it had done everything possible to protect the plant, which suffered a triple meltdown after being struck by a towering tsunami.
The nuclear accident, the world’s worst since Chernobyl 25 years earlier, caused massive radiation leaks and forced the evacuation of more than 150,000 people, most of whom have yet to return to their homes.
Tepco executives agreed that building coastal defences to defend the plant against tsunami higher than those previously recorded in the region was “indispensable”, according to the document, which was discussed at a meeting at the plant in September 2008 – two and a half years before the disaster.
The utility disclosed the document this week during a lawsuit brought by more than 40 Tepco shareholders who are demanding damages totalling 5.5 trillion yen from company executives.
Tepco has always insisted that it was powerless to take precautions against a tsunami of the size that struck Japan’s north-east coast in March 2011, killing almost 16,000 people.
In April 2012, for instance, the company said that based on expert knowledge of previous tsunami in the region, the March 2011 disaster “could not have been foreseen, and Tepco also considers the height [scale] of the tsunami that followed this earthquake to have been unpredictable ”.
The company has voiced similar claims during the ongoing damages case at Tokyo district court, but Kyodo News quoted lawyers for the plaintiffs as saying that the internal document proved that Tepco “had clearly recognised as of  that measures against tsunami were inevitable, contradicting the company’s explanations so far”.
The document showed Tepco recognised the need to improve tsunami defences as “inevitable, as we cannot help but expect bigger tsunami than currently projected”, Japanese media said.
Plaintiffs cited a government report showing that Tepco had predicted in June 2008 that the Fukushima Daiichi plant could be hit by tsunami waves of up to 15.7 metres in height following a major offshore earthquake. Tepco failed to act on that prediction, and on concerns raised in the internal report, which was discussed by executives at Fukushima three months later.
In response, Tepco told the court that it was wrong to conclude that the 2008 tsunami estimate would have prompted the firm to improve the plant’s defences, “because there were differences of opinion, even among experts, on how to estimate [the size] of an earthquake”, the newspaper Asahi Shimbun said.