Japan’s nuclear regulators and the plant’s operator, Tokyo Electric Power, or Tepco, have said that the magnitude 9.0 earthquake and 45-foot tsunami on March 11 that knocked out cooling systems at the Fukushima Daiichi Nuclear Power Plant were far larger than anything that scientists had predicted. That conclusion has allowed the company to argue that it is not responsible for the triple meltdown, which forced the evacuation of about 90,000 people.

But some insiders from Japan’s tightly knit nuclear industry have stepped forward to say that Tepco and regulators had for years ignored warnings of the possibility of a larger-than-expected tsunami in northeastern Japan, and thus failed to take adequate countermeasures, such as raising wave walls or placing backup generators on higher ground.

They attributed this to a culture of collusion in which powerful regulators and compliant academic experts looked the other way while the industry put a higher priority on promoting nuclear energy than protecting public safety. They call the Fukushima accident a wake-up call to Japan to break the cozy ties between government and industry that are a legacy of the nation’s rush to develop after World War II.

Ex post rationalizations or explanations?

Update: And this from the MIT Technology Review.

A year after Japan’s largest earthquake and most destructive tsunami led to the Fukushima nuclear accident, experts say the industry has moved beyond any claims of absolute safety. As happened after the 2010 BP oil spill in the Gulf of Mexico, experts now recognize that any technology—whether it’s deepwater drilling or nuclear fission—can and will fail, and operators must prepare for the worst.

“Fukushima Daiichi … was not just due to an inadequately sized seawall—that is the wrong way to look at it,” says Edward Blandford, a professor of nuclear security at the University of New Mexico and a postdoctoral fellow at Stanford University’s Center for International Security and Cooperation. “The events at Fukushima Daiichi were due to a series of failures, including failures in plant defensive actions, mitigation efforts, and emergency response. If backup equipment had been stored in waterproof vaults or higher elevations, the accident would have most likely been avoided.”

Nuclear operators and regulators say they embrace the need to anticipate the worst. Nuclear utilities in the U.S. launched a program this winter to stock portable reactor-cooling equipment at regional depots, and last week, the U.S. Nuclear Regulatory Commission (NRC) approved new mandates requiring operators to prepare for events worse than what a reactor is designed to handle—or “beyond design-basis events,” in industry lingo.