The following is the gist of an interim report of a government panel investigating the Fukushima nuclear accident released on Dec. 26.
The following is the gist of an interim report of a government panel investigating the Fukushima nuclear accident released on Dec. 26.
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Although the center was established about 5 kilometers from the Fukushima No. 1 nuclear power plant, no forethought was given to the possibility of a simultaneous nuclear accident and natural disaster. Therefore, the center's structure did not take into consideration the possibility of an increase in radiation levels.
Communication was insufficient between the fifth floor office where the relevant Cabinet ministers, the chairman of the Nuclear Safety Commission and executives of Tokyo Electric Power Co. had gathered to make decisions in response to the accident and the team of high-ranking ministry officials who had gathered at the basement.
Workers erroneously thought the isolated condenser (IC) was operating normally. It is unlikely that those working at the plant as well as those at TEPCO headquarters thoroughly understood the functioning of the IC. This was extremely inappropriate and was likely a major factor that led to a delay in cooling the reactor core.
Workers manually stopped the high pressure coolant injection because of concerns equipment was damaged and radioactive materials were leaking. However, without securing an adequate alternative means of pumping in water, the workers understated the risks involved and failed to reduce the pressure to allow for alternative pumping in of water.
If the SPEEDI calculation results had been used, the various local governments and residents would have been able to select more appropriate evacuation routes and methods. Evacuation instructions issued by the central government did not reach all the concerned local governments in the targeted evacuation zone in an expedient manner, and the contents of those instructions also lacked specifics.
The central government repeatedly said "there will be no immediate effect on human health" in providing information related in particular to the melting of the reactor cores, the dangerous situation at the No. 3 reactor and the effects of radiation on human health. That explanation was difficult to understand.
The delay in releasing information that should have been disclosed immediately and the tendency to make vague explanations were not appropriate in terms of communicating the risks involved.
Releasing contaminated water into the ocean without prior explanation to neighboring nations led to distrust of Japan's response to the nuclear accident among those nations.
Revisions of inspection guidelines for anti-quake design took five years and were completed in September 2009. However, the process was not used as an opportunity to come up with new measures to deal with tsunami.
No confirmed efforts were made by the regulatory agency to present methods to appraise tsunami or set appraisal standards for the effectiveness of anti-tsunami measures.
In 2008, when the risk of tsunami was again considered, an expected tsunami exceeding 15 meters was given for the Fukushima No. 1 nuclear power plant. But TEPCO officials judged that the figure was nothing more than a hypothetical one.
From a study released that year, TEPCO also obtained wave heights exceeding 9 meters through calculations using a source model of the Jogan tsunami of 869. But TEPCO officials did not view such studies as being based on sufficient grounds, including the uncertainty of the tsunami source model. No efforts started for specific measures.
There was insufficient recognition of the risk of tsunami. Although consideration began in 1992, it did not lead to regulations. Electric power companies could decide what measures to take.
(1) Secure independence and transparency. There will be a need to have the agency assume the responsibility to explain its actions along with giving it the proper authority, funding and personnel.
(2) There will be a need for specialized ability to allow for providing advice and guidance based on expert knowledge during emergency situations as well as management ability to allow for efficient functioning of the organization.
(3) There will be a need for persistent scrutiny of developments within academic organizations, specialized journals and overseas regulatory agencies as well as to continuously obtain the knowledge needed for regulatory purposes.
(1) TEPCO did not implement measures based on an assumption of a severe accident caused by tsunami as was the case with this accident. The same thing can be said about the regulatory agencies.
(2) For events in which an extremely large scale of damage is forecast, even if the evaluation is made that the probability of such events is low, there is a need to recognize the risk and implement necessary measures.
(3) Measures to deal with multiple disasters considered unlikely will be an important point in the future review of the safety of nuclear power plants.
(4) There is no denying the weakness in a perspective that took into consideration a much larger picture. The excuse that responses could not be made because of the special nature of the situation, in which a tsunami went beyond expectations, will be unacceptable.
From the above points, there will be a need for a conversion of the framework for the fundamental thinking related to anti-disaster measures for gigantic systems that could lead to serious damage.
The interim report can be viewed at the government panel's website at (http://icanps.go.jp/).