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Learning Again from the Catastrophe

Published on Fev.20 ,2014 : The Denki shinbun(The Electric Daily News)
Shojiro Matsuura
Chairman of JANSI

Three years have passed since that catastrophe. As a person who is involved in nuclear safety issues, I was facing and kept thinking, for these last three years, about challenges posed by the catastrophe. The Atomic Energy Society of Japan (AESJ), a group of nuclear experts, is now gathering opinions from its members about “messages from the Fukushima accident to the next generation.” I hear that the AESJ is planning to publish the results as a feature article for the upcoming March issue of its journal.

Here in this article, I would like to focus on two essential but alarming challenges that are especially difficult to address.

One of the challenges is issues with safety evaluations. To the question “Is it possible to prevent accidents like Fukushima with the current technology of light water reactors?”, many experts here and abroad have presented the viewpoint “It is able to prevent if proper facilities are fully equipped based on current scientific and technological knowledge and if operations of those facilities during severe accidents are thoroughly trained.

On the other hand, several groups of experts made such a point as the one published in the American Society of Mechanical Engineers’ report on the Fukushima accident, “Forging a New Nuclear Safety Construct”. The report says, “Another in-depth research is indispensable to deal with rare events with potentially extreme consequences.” This, too, is a shared view among nuclear safety experts.

While the need for a research to address this point is recognized both here and abroad, no specific research method or implementation plan have been proposed yet. The reason probably comes from the fact that, even if the research covers events caused by natural disasters or human-caused events including terrorism, proper predictions are impossible solely based on the current scientific and technological insights and methods.

Realistic and feasible alternatives are; (1) to implement as feasible measures as possible to deal with predictable risks by scientific and technological knowledge, and (2) to set unpredictable risks as residual risks against other risks and then determine if they are socially acceptable or not. To make these alternatives reasonable, risk literacy of the public at large must be on a certain level. I strongly hope for a strategic research on social reforms to make such alternatives possible.

 

Another challenge is a comprehensive and microscopic research about low-dose radiation’s effects on human health.

Even today, three years after the Fukushima accident, most of approximately 150,000 evacuees have not come home yet. The major reason appears to be that, each evacuee, the public administration and society in general have not understood or been convinced of low-dose radiation’s effects on human health.

 

As for effects of low doses, a vast amount of epidemiological research already produced sufficient evidence for preventing radiation hazards during radiological work. Based on these findings, radiological work has been managed properly.

 

Scientific and epidemiological data show that there are no health effects in the low-dose region (100 mSv a year or less). There are also more conservative evaluations based on the radiation protection viewpoint of “the less exposure the better” where health effects in the low-dose region are deduced from the linear relationship between annual exposure and health effects observed at 100 mSv or more. However, under the post-Fukushima social circumstances, the general public are not convinced of these explanations.

 

In that case, why don’t we think that we are now required to take a different perspective from epidemiological studies, to examine all kinds of radiation effects at low doses (effects on different levels, from whole body, internal organs, tissue, cells and genes) and to show clearer scientific evidence? I suppose that we have an environment civilized enough to obtain scientific and technical means for that purpose.

 

The Fukushima accident taught us that, in order to calmly discuss, make choices and judgments of nuclear power as an important energy source for the future of mankind, it is indispensable to conduct a strategic and comprehensive research on the above challenges.

 

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