The committee appointed by the government to investigate last year’s accident at the Fukushima No. 1 nuclear power plant released its final report on July 23.
The report, which followed reports by two other Fukushima disaster inquiry panels, one set up by the Diet and the other created by a private-sector organization, marked an end to the initial round of efforts by third parties to discover and analyze the causes of the devastating accident.
Unfortunately, however, none of the panels has been able to work out the details of how and why the accident occurred and led to such a tremendous scale of damage.
It is vital to continue efforts to pin down the causes.
The collective findings of the three investigative panels have clarified, to a considerable extent, the cultural and other background factors behind the accident.
Their inquiries have revealed how the “safety myth,” the unfounded belief that no serious accident would take place at Japan’s nuclear power plants, was formed. They have also disclosed disturbing derelictions on the part of the government and a lack of awareness among Tokyo Electric Power Co. and other businesses involved concerning their direct responsibility for the accident.
It has also become clear that the local governments failed to recognize the safety risks and take effective measures to prevent such a disaster.
All these structural problems caused serious confusion following the accident.
The lessons learned should be used to ensure the effectiveness of the new nuclear safety regime, to be built around a new nuclear regulatory commission.
The problem is that there remain many unanswered questions about what actually happened in the crippled reactors.
A good model for investigations into large-scale accidents was supplied by the U.S. presidential commission charged with investigating the Space Shuttle Challenger disaster in 1986.
The report released by the Rogers Commission showed how the panel determined that the midair breakup of the space shuttle was caused by the failure of a component of its right solid rocket booster. The commission gathered as many fragments from the spacecraft and related photographs as possible and ruled out all other causes one by one. The report described the chain of events leading to the disintegration of the spacecraft on the millisecond time scale.
The Fukushima disaster, of course, is different from the Challenger disaster in many respects. In particular, it is almost impossible to look directly inside the stricken reactors because of high levels of radiation.
But it must have been possible to conduct an experiment to reconstruct conditions at the reactors by using other reactors of the same type in Japan or building a small experimental plant.
Computer-based analyses could have been used to examine how things might have been different if other choices and decisions had been made after the power supply to the plant was cut off. They could have answered such questions as what if this valve had been opened, or whether the hydrogen explosions could have been prevented if nitrogen had been injected at this point.
Such efforts would have allowed the panel to get closer to finding answers to such key questions as whether the core cause of the accident was problems with the structures of the reactors and buildings, or human errors.
Yotaro Hatamura, who heads the government’s investigative committee, himself said at a July 23 news conference that he had wanted to carry out an experiment to reproduce conditions at the time of the accident.
Hatamura said the panel didn’t have enough time or manpower for the work needed. But the panel was set up exactly for this kind of work.
The panel’s report cannot be an end to the efforts to get to the bottom of the accident.
Japan has the responsibility to clear up the causes of the disaster for the benefits of the entire world.
We suggest that the new nuclear regulatory commission put together a team of experts comprising researchers and engineers to conduct engineering studies into the accident.
Unless serious efforts to uncover the whole picture continue, there can be no “resolution” of the disaster.
--The Asahi Shimbun, July 24
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