Editor's note: This is the last in a four-part series on the problems, such as the safety myth, inherent in the nation's nuclear power generation industry.
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The moment seismologist Kojiro Irikura felt a massive shaking in Tokyo's Kasumigaseki district on March 11, he wondered whether a nuclear power plant somewhere might have been damaged. But deep down, he may have already known the answer.
Irikura, 70, professor emeritus at Kyoto University, called the Nuclear Safety Commission of Japan and learned that reactors at the Fukushima No. 1 nuclear power plant had stopped.
The magnitude-9 Great East Japan Earthquake spawned a tsunami, which overwhelmed a 10-meter-tall coastal levee and swamped the plant.
It overturned the conventional wisdom that a gigantic earthquake would not occur in the Japan Trench, where plates are relatively old.
Irikura, who has chaired the Nuclear Safety Commission of Japan's Investigatory Advisory Board on Assessment of Seismic Safety since 2007, believes that warnings about earthquake risks to nuclear power plants were not taken seriously for many years.
He became involved in the nuclear power industry in the early 1990s, when he was asked by the government to take part in safety screening for a nuclear fuel recycling facility in Aomori Prefecture.
Irikura argued that hidden active faults near the facility should be taken into account. But his calls fell on deaf ears, and he was not invited to the screening process after several sessions.
Irikura became a university faculty member in 1968, a year after construction started on the Fukushima No. 1 nuclear power plant. Seismology was still in its early years, and the plate tectonics theory was not yet established.
While nuclear power plants were required to be built three times as sturdy as general structures, there were virtually no concrete measures to protect against tsunami.
In 1978, the government introduced its first guidelines, which require nuclear power plants to withstand an earthquake anticipated from nearby active faults or undersea plate boundaries.
Seismologists and some nuclear experts called on the government to review the earthquake-resistance guidelines to reflect new scientific findings, but those calls long went unheeded.
"Japan was still building many nuclear power plants," said Kenji Sumita, 80, professor emeritus at Osaka University, who specializes in nuclear engineering. "A delay in discussions (on enhancing earthquake resistance of nuclear power plants) was convenient for electric power companies."
After the magnitude-7.3 Great Hanshin Earthquake in 1995, the Nuclear Safety Commission of Japan started to verify whether nuclear power plants could survive a similar earthquake.
Irikura was angry because the commission concluded in only eight months that the earthquake-resistance guidelines were appropriate.
Irikura discovered that certain areas were seriously damaged by the 1995 quake due to their subsurface structures even though they did not sit on active faults.
He said subsurface structures should be closely examined for all nuclear power plants.
In 2001, the commission finally started a review of the earthquake-resistance guidelines, but the discussions made little progress.
Members were divided over how the impact of a major earthquake should be incorporated because of its low probability. Irikura said it should be strictly evaluated based on research.
But nuclear researchers told him that nuclear power plants are equipped with safety measures other than those for earthquakes and that damage can be prevented even if an earthquake is a little stronger than expected.
Irikura said he did not feel that they were paying serious attention to potential risks.
The earthquake-resistance guidelines were revised in 2006. They required nuclear power plants to withstand a 20 to 30 percent stronger earthquake.
They also included provisions for tsunami protection for the first time.
But Tokyo Electric Power Co. postponed countermeasures based on the new guidelines for the Fukushima plant.
Specific procedures to implement the guidelines were compiled in December, only three months before the Fukushima plant was crippled by the Great East Japan Earthquake.
Both the earthquake and tsunami exceeded levels anticipated by the revised guidelines.
Masataka Shimizu, president of Tokyo Electric Power Co., the plant's operator, apologized at the company's head office on March 13.
"We feel the deepest regrets for the serious accident even though it was caused by the most powerful earthquake Japan experienced," Shimizu said.
Seismologist Kunihiko Shimazaki, 65, said he could have done more to prevent damage by the Great East Japan Earthquake.
Shimazaki, professor emeritus at the University of Tokyo, is president of the Coordinating Committee for Earthquake Prediction, Japan.
He also chairs the Earthquake Research Committee's subcommittee for long-term evaluations, which has predicted the scale and probability of anticipated earthquakes in Japan since the Great Hanshin Earthquake.
In February, the subcommittee held discussions on the Jogan Earthquake of 869, which produced a tsunami that hit roughly the same region as the March 11 tsunami.
Before the earthquake, the subcommittee was expected in April to announce the results of discussions and warn about the dangers of tsunami.
Shimazaki said had his panel completed the discussions earlier, damage from the March 11 tsunami, including that to the Fukushima plant, would have been reduced.
"I have regrets as someone responsible for preventing damage from earthquakes," Shimazaki said in a speech on May 12.
Like Irikura, Shimazaki has run into the wall of the electric power industry.
Every time his panel released the implications of an earthquake near a nuclear power plant, electric power industry officials maintained that the presumed magnitude was too large.
Shimazaki said nuclear power plants, which would pose a serious danger in case of an accident, should be prepared for a worst-case earthquake.
Still, he said the problem is not limited to the electric power industry.
He said Japanese society at large is responsible for postponing concrete measures to deal with risks of a major earthquake on grounds that such an earthquake is rare and one cannot deal with every risk.
"In the 16 years after the Great Hanshin Earthquake, everybody has forgotten the truly important things to protect," Shimazaki said. "All of Japan has stopped thinking."
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