Was the tsunami foreseeable?

17 Octobre 2018

October 15, 2018

Whether tsunami predictable, damage avoidable focus of TEPCO nuclear disaster trial

https://mainichi.jp/english/articles/20181015/p2a/00m/0na/028000c

TOKYO -- The criminal trial of three top former Tokyo Electric Power Co. (TEPCO) officials indicted on charges of professional negligence resulting in death and injury over the 2011 Fukushima nuclear disaster will reach a climax as the defendants will begin to answer questions from prosecutors and their defense lawyers on Oct. 16.

They will face these two focal questions: Was it possible for them to predict the massive tsunami that triggered the triple core meltdowns at the TEPCO plant in the northeastern Japan prefecture of Fukushima, and was the damage from the natural disaster avoidable?

The three former TEPCO executives to undergo questioning are former Chairman Tsunehisa Katsumata and former vice presidents Ichiro Takekuro and Sakae Muto. All of them essentially answered no to those two questions in the opening session of the trial in June last year; that they could not foresee the tsunami, and therefore have no criminal responsibility for the damage caused by the natural disaster leading to the nuclear accident.

This unusual trial took several years to come to the Tokyo District Court as prosecutors' two refusals to indict the three ex-executives were overridden each time by the committee for the inquest of prosecution. As a result, the defendants were forcibly indicted by lawyers serving as prosecutors.

The trial's eight months of cross examinations of various witnesses that ended on Oct. 3 gave rise to the view that the former management essentially postponed taking sufficient countermeasures against the level of tsunami that hit the Fukushima No. 1 Nuclear Power Station on March 11, 2011 out of cost considerations.

The gushing seawater sent to the Fukushima shore by the Great East Japan Earthquake halted diesel power generators at the plant, making it impossible to cool down the nuclear fuel cores that melted down to the ground and resulted in the release of a massive amount of radioactive materials into the surrounding environment. This nuclear disaster forced the evacuation of tens of thousands of residents around the plant, and many of them are still unable to return to their homes seven years after the incident.

--- 'Management first, countermeasures second'?

In the 24th session of the trial on Sept. 5, an affidavit given to the prosecution by a former top TEPCO official in charge of tsunami countermeasures was read out: "Our business environment was deteriorating because of the Niigata Chuetsu offshore earthquake of 2007 that halted the Kashiwazaki-Kariha nuclear power station, and we wanted to prevent the Fukushima No. 1 plant from stopping by all means."

The statement said that the former management once decided to introduce measures to protect against possible tsunami damage but decided to postpone them after finding out that they were more costly than expected, implying that managerial decisions were behind the delay.

Earlier, all TEPCO tsunami countermeasure officials who testified before the court had agreed that such steps must be taken in response to a 2002 government estimate that "a massive tsunami could occur off the Fukushima coast." Their testimonies, however, did not explain why the process was delayed.

According to the affidavit, the three defendants including Katsumata approved countermeasures at a top-level TEPCO meeting in February 2008 after a report was presented to the meeting that an estimated wave 7.7 meters high or more could hit the Fukushima facility. But more detailed calculations showed that the potential maximum height would be 15.7 meters, and it was reported to Muto, the former vice president, that it was now estimated to cost tens of billions of yen and take more than four years to complete the countermeasures. Following this estimate, Muto decided to ask experts to re-evaluate the reliability of the 2002 government estimate, effectively shelving steps to mitigate damage from tsunami.

Implementing tsunami countermeasures could mean a halt to the Fukushima nuclear plant as construction work could not be completed in time. If that was the case, it was better to work behind closed doors and influence regulators so that they would clear the facility as safe, according to the testimony by a former tsunami countermeasure official presented in September this year.

If the management really postponed measures to curb tsunami damage as explained in the affidavit that would fit with the argument by the prosecution -- as highlighted by designated lawyers in the special trial. Another focal point of the trial would be how the three defendants would explain this point.

Moreover, it is still not clear what Katsumata, the then chairman, and Takekuro, another vice president back then, were thinking about the results of tsunami damage estimates reported to the February 2008 meeting. The level of involvement by these two defendants is also a highlight of the questioning session starting Oct. 16.

According to the 2002 government estimate, there was a 20 percent chance that a magnitude-8 earthquake could occur along the Japan Trench off the northeastern Japan coast of Sanriku and the eastern coast of Boso during the next 30 years. Fukushima lies alongside this area, which triggered three major tremblers that caused massive tsunami during the past 400 years as shown in historical records.

Professor Fumihiko Imamura of Tohoku University, a tsunami dynamics specialist, questioned the validity of the government evaluation during the trial saying, "It cannot be ignored but has many issues," siding with the three defendants. But professor emeritus Kunihiko Shimazaki of the University of Tokyo, a seismologist who headed an expert panel that compiled the 2002 estimate, testified that the panel's conclusion didn't face any objections from panel members. "It was a consensus conclusion. The (2011 nuclear) accident could have been avoided if countermeasures were taken according to the long-term evaluation," Shimzaki said. His testimony indicated the defendants failed to act properly.

In class action damages suits filed by evacuees from the 2011 nuclear accident and others, five district courts have ruled that the massive tsunami that triggered the core meltdowns could have been foreseen based on the 2002 estimate. But criminal trials require stronger proof and sometimes end with different conclusions than civil suits.

Meanwhile, about the question of whether the damage caused by the tsunami was avoidable, a former TEPCO employee at the time of the nuclear disaster said in the trial that "damage from tsunami could not be prevented even if countermeasures were taken." The superior of the employee testified that "countermeasures, if implemented, could be too late, but I think something could have been done."

A former employee of the Japan Atomic Power Co. testified that his company constructed soil embankments around its Tokai No. 2 nuclear power station in the village of Tokai in Ibaraki Prefecture to the south of Fukushima, to fend off a tsunami to a height of 12.2 meters. This measure was based on the 2002 government estimate, and the facility was spared of damage from the 2011 earthquake and tsunami. The prosecution argues that such a measure would have prevented the Fukushima nuclear facility from causing the devastating damage.

(Japanese original by Ei Okada, Science & Environment News Department, and Masanori Makita, City News Department)