OMAEZAKI, Japan >> The nuclear power plant, lawyers argued, could not withstand the kind of major earthquake that new seismic research now suggested was likely.

If such a quake struck, electrical power could fail, along with backup generators, crippling the cooling system, the lawyers predicted. The reactors would then suffer a meltdown and start spewing radiation into the air and sea. Tens of thousands in the area would be forced to flee.

Although the predictions sound eerily like the sequence of events at the Fukushima Daiichi plant following the March 11 earthquake and tsunami, the lawsuit was filed nearly a decade ago to shut down another plant, long considered the most dangerous in Japan — the Hamaoka station.

It was one of several quixotic legal battles waged — and lost — in a long attempt to improve nuclear safety and force Japan’s power companies, nuclear regulators and courts to confront the dangers posed by earthquakes and tsunamis on some of the world’s most seismically active ground.

The lawsuits reveal a disturbing pattern in which operators underestimated or hid seismic dangers to avoid costly upgrades and keep operating. And the fact that virtually all these suits lost reinforces the widespread belief in Japan that a culture of collusion supporting nuclear power, including the government, nuclear regulators and plant operators, extends to the courts as well.

Yuichi Kaido, who represented the plaintiffs in the Hamaoka suit, which lost in a district court in 2007, said that victory could have led to stricter earthquake, tsunami and backup generator standards at plants across the nation.

“This accident could have been prevented,” Kaido, also the secretary-general of the Japan Federation of Bar Associations, said of Fukushima Daiichi. The operator of the plant, Chubu Electric Power Co., temporarily shut down Hamaoka’s two active reactors over the weekend, following an extraordinary request by Prime Minister Naoto Kan.

After strengthening the plant’s defenses against earthquakes and tsunamis, a process that could take a couple of years, the utility is expected to restart the plant.

Japan’s plants are all located in coastal areas, making them vulnerable to both quakes and tsunamis. The tsunami is believed to have caused the worst damage at the Fukushima plant, though evidence has begun emerging that the quake may have damaged critical equipment before the waves struck.

The disaster at Fukushima Daiichi, the worst nuclear accident since Chernobyl, directly led to the suspension of Hamaoka here in Omaezaki, a city about 120 miles southwest of Tokyo. But Kan’s decision was also clearly influenced by a campaign, over decades, by small groups of protesters, lawyers and scientists, who sued the government or operators here and elsewhere.

They were largely ignored by the public. Harassment by neighbors, warnings by employers and the reluctance of young Japanese to join antinuclear groups have diminished their numbers.

But since the disaster at Fukushima and especially the suspension of Hamaoka, the aging protesters are now heralded as truth-tellers, while members of the nuclear establishment are being demonized.

On Friday, as Chubu Electric began shutting down a reactor at 10 a.m., Eiichi Nagano, 90, and Yoshika Shiratori, 78, were battling strong winds on the shoreline leading to the plant here. Shiratori, a leader of the lawsuit, led the way as Nagano followed with a sprightly gait despite a bent back. The two men scrambled up a dune, stopping only before a “No Trespassing” sign.

“Of course, we’re pleased about the suspension,” Nagano said, as the strong wind seemed to threaten to topple him. “But if we had done more, if our voices had been louder, we could have prevented the disaster at Fukushima Daiichi. Fukushima was sacrificed so that Hamaoka could be suspended.”

UNHEEDED WARNINGS

In 1976, a resource-poor Japan still reeling from the shocks of the oil crisis was committed fully to nuclear power to achieve greater energy independence, a path from which it never strayed despite growing doubts in the United States and Europe.

That year, as Hamaoka’s No.1 reactor started operating and No.2 was under construction, Katsuhiko Ishibashi, a seismologist and now professor emeritus at Kobe University, publicized research showing that the plant lay directly above an active earthquake zone where two tectonic plates meet. Over the years, further research would back up Ishibashi’s assessment, culminating in a prediction last year by the government’s own experts that there was a nearly 90 percent chance that a magnitude 8.0 quake would hit this area within the next 30 years.

After the 1995 Kobe earthquake, residents in this area began organizing protests against Chubu Electric. They eventually sued the utility in 2003 to stop the plant’s reactors, which had increased to four by then, arguing that the facility’s quake-resistance standards were simply inadequate in light of the new seismic predictions.

In 2007, a district court ruled against the plaintiffs, finding no problems with the safety assessments and measures at Hamaoka. The court appeared to rely greatly on the testimony of Haruki Madarame, a University of Tokyo professor and promoter of nuclear energy, who since April 2010 has been the chairman of the Nuclear Safety Commission of Japan, one of the nation’s two main nuclear regulators.

Testifying for Chubu Electric, Madarame brushed away the possibility that two backup generators would fail simultaneously. He said that worrying about such possibilities would “make it impossible to ever build anything.” After the Fukushima Daiichi disaster, Madarame apologized for this earlier comment under questioning in Parliament. “As someone who promoted nuclear power, I am willing to apologize personally,” he said.

In the early days of nuclear power generation in Japan, the government and nuclear plant operators assured the public of the safety of plants by promising that they would not be located on top of active fault lines, Ishibashi, the seismologist, said in an interview.

But he said that advances in seismology have led to the gradual discovery of active fault lines under or near plants, creating an inherent problem for the operators and the government and leading to an inevitable conclusion for critics of nuclear power.

“The Japanese archipelago is a place where you shouldn’t build nuclear plants,” Ishibashi said.

Advances in seismology also led to lawsuits elsewhere. Only two courts have issued rulings in favor of plaintiffs, but those were later overturned by higher courts. Since the late 1970s, 14 major lawsuits have been filed against the government or plant operators in Japan, which until March 11 had 54 reactors at 18 plants.

In one of the two cases, residents near the Shika nuclear plant in Ishikawa, a prefecture facing the Sea of Japan, sued to shut down a new reactor there in 1999. They argued that the reactor, built near a fault line, had been designed according to outdated quake-resistance standards.

A district court ordered the shutdown of the plant in 2006, ruling that the operator, Hokuriku Electric Power Co., had not proven that its new reactor met adequate quake-resistance standards, given new knowledge about the area’s earthquake activity.

Kenichi Ido, the chief judge at the district court who is now a lawyer in private practice, said that, in general, it was difficult for plaintiffs to prove that a plant was dangerous. What is more, because of the technical complexities surrounding nuclear plants, judges effectively tended to side with a national strategy of promoting nuclear power, he said.

“I think it can’t be denied that a psychology favoring the safer path comes into play,” Ido said. “Judges are less likely to invite criticism by siding and erring with the government than by sympathizing and erring with a small group of experts.” 

That appears to have happened when a higher court reversed the decision in 2009 and allowed Hokuriku Electric to keep operating the reactor. In that decision, the court ruled that the plant was safe because it met new standards for Japan’s nuclear plants issued in 2006.

Critics say that this exposed the main weakness in Japan’s nuclear power industry: weak oversight. 

The 2006 guidelines had been set by a government panel composed of many experts with ties to nuclear operators. Instead of setting stringent industrywide standards, the guidelines effectively left it to operators to check whether their plants met new standards.

In 2008, the Nuclear and Industrial Safety Agency, Japan’s main nuclear regulator, said that all the country’s reactors met the new quake standards and did not order any upgrades.

CONCEALING FACTS

Other lawsuits reveal how operators have dealt with the discovery of active fault lines by underestimating their importance or concealing them outright, even as nuclear regulators remained passive.

For 12 years, Yasue Ashihara has led a group of local residents in a long and lonely court battle to halt operations of the Shimane nuclear plant, which sits less than five miles from Matsue, a city of 200,000 people in western Japan.

Ashihara’s fight against the plant’s operator, Chugoku Electric Power, revolves around not only the discovery of a previously unknown active fault line, but an odd tug of war between her group and the company about the fault’s length, and thus the strength of the earthquakes it is capable of producing.

The utility has slowly accepted the contention of Ashihara’s group by repeatedly increasing its estimate of the size of the fault.

Yet a district court last year ruled in favor of Chugoku Electric Power, accepting its argument that its estimates were based on the better scientific analysis.

“We jokingly refer to it as the ever-growing fault line,” said Ashihara, 58, who works as a caregiver for the elderly. “But what it really means is that Chugoku Electric does not know how strong an earthquake could strike here.”

Her group filed the lawsuit in 1999, a year after the operator suddenly announced that it had detected a five-mile-long fault near the plant, reversing decades of claims that the plant’s vicinity was free of active faults.

Chugoku Electric said the fault was too small to produce an earthquake strong enough to threaten the plant, but Ashihara’s suit cited new research showing the fault line could in fact be much longer, and produce a much stronger earthquake. It got a boost in 2006, when a seismologist announced that a test trench that he had dug showed the fault line to be at least 12 miles long, capable of causing an earthquake of magnitude 7.1.

After initially resisting, the company reversed its position three years ago to accept the finding. But a spokesman for the Chugoku Electric said the plant was strong enough to withstand an earthquake of this size without retrofitting.

“This plant sits on solid bedrock,” said Hiroyuki Fukada, assistant director of the visitor center for the Shimane plant, adding that it had a 20-foot, ferro-concrete foundation. “It is safe enough for at least a 7.1 earthquake.”

However, researchers now say the fault line may extend undersea at least 18 miles, long enough to produce a magnitude 7.4 earthquake. This prompted Ashihara’s group to appeal last year’s ruling.

Ashihara said she has waged her long fight because she believes the company is understating the danger to her city. But she says she has at times felt ostracized from this tightly bound community, with relatives frowning upon her drawing attention to herself.

Still, she said she hoped the shutdown of Hamaoka would help boost her case. She said local residents had already been growing skeptical of the Shimane plant’s safety after revelations last year that the operator falsified inspection records, forcing it to shut down one of the plant’s three reactors.

In Ashihara’s case, the nuclear operator acknowledged the existence of the active fault line in court. In the case of Kashiwazaki-Kariwa nuclear plant in Niigata, a prefecture facing the Sea of Japan, Tokyo Electric Power Co., or TEPCO, the utility that also operates Fukushima Daiichi, did not disclose the existence of an active fault line until an earthquake forced it to. 

In 1979, residents sued the government to try overturn its decision granting TEPCO a license to build a plant there. They argued that nuclear regulators had not performed proper inspections of the area’s geology — an accusation that the government would acknowledge years later — and that an active fault line nearby made the plant dangerous. In 2005, the Tokyo High Court ruled against the plaintiffs, concluding that no such fault line existed.

But in 2007, after a 6.8-magnitude earthquake damaged the plant, causing a fire and radiation leaks, TEPCO admitted that, in 2003, it had determined the existence of a 12-mile-long active fault line in the sea nearby.

WEIGHING THE CHANCES

The decision to suspend Hamaoka has immediately raised doubts about whether other plants should be allowed to continue operating. The government based its request on the prediction that there is a nearly 90 percent chance that a magnitude 8.0 earthquake will hit this area within the next 30 years. But critics have said that such predictions may even underestimate the case, pointing to the case of Fukushima Daiichi, where the risk of a similar quake occurring had been considered nearly zero.

“This is ridiculous,” said Hiroaki Koide, an assistant professor at the Research Reactor Institute at Kyoto University. “If anything, Fukushima shows us how unforeseen disasters keep happening. There are still too many things about earthquakes that we don’t understand.” 

Until March 11, Koide had been relegated to the fringes as someone whose ideas were considered just too out of step with the mainstream. Today, he has become an accepted voice of conscience in a nation re-examining its nuclear program.

For the ordinary Japanese who waged lonely battles against the nuclear establishment for decades — mostly graying men like Nagano and Shiratori — the Hamaoka plant’s suspension has also given them their moment in the sun.

The two worried, however, that the government will allow Hamaoka to reopen once Chubu Electric has strengthened defenses against tsunamis. Chubu Electric announced that it would erect a 49-foot high seawall in front of the plant, which is protected only by a sand dune.

“Building a flimsy seawall isn’t enough,” Shiratori said. “We have to keep going after Chubu Electric in court and shut down the plant permanently.”

“That’s right,” Nagano said, the smallness of his bent frame emphasized by the enormous plant behind him. “This is only the beginning.”