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Before and After the Fukushima Daiichi Accident

Published on Sep. '2013 : The Magagine of Atomic Energy Society of Japan
Shojiro Matsuura
Chairman, Japan Nuclear Safety Institute
President, Japan Atomic Energy Agency

Since the beginning, it has generally and strongly been recognized that the primary objective to ensure safety in the development and use of nuclear energy is to protect the general public from the risk of radiation hazards associated therewith. As a framework to achieve this objective, the establishment and maintenance of an overall defense-in-depth system for the planning, design, manufacturing, and operation of facilities, as well as the embodiment, improvement, and steadfast maintenance of safety culture on the major premise of ensuring safety have been laid down. The foundation of this basic framework has not changed from the beginning. Depending on the stage of development and use, however, priorities and focus areas have rigorously been reviewed, in particular, based on the lessons learned from major accidents.

Typical accidents in which severe regrets and lessons were engraved include: (1) the Windscale accident (U.K.), (2) SL-1 accident (U.S.), (3) TMI-2 accident (U.S.), and (4) Chernobyl-4 accident (former Soviet Union). Lessons learned include the prevention of release of a large amount of radioactive material in (1), the prevention of reactivity accidents in (2), and the improvement of the relationship between workers and equipment and the grasp of weaknesses within the system through probabilistic analysis in (3). In (4), the importance of maintaining safety culture in the course of operation was strictly pursued in addition to the lessons learned in (1) and (2). In particular, the lessons learned before and after the TMI accident and the Chernobyl accident have had a major impact worldwide on the measures to reinforce nuclear safety.

The Fukushima Daiichi accident also had a worldwide impact and a great majority of evacuees still cannot go home even after the elapse of two and a half years since the accident. What kind of lessons should we learn from it? How should we impose a radical reform on our way of pursuing the development and use of nuclear energy before and after the accident? Since immediately after the accident, the government, the Diet, and TEPCO have intensively conducted investigation into the causes of the accident. Investigation reports on findings have also been published. Based on the information contained in them, professional organizations and expert groups both at home and abroad are continuously publishing reports on what and how action should be taken into the future.

Among these, the most obvious and severe understanding is that “this accident shows us that similar accidents could happen unless licensees do what they should do.” On the other hand, it has been pointed out that “even if an unprecedented event like the major earthquake and massive tsunami that caused the accident should occur, the present level of light water reactor technology can deal with it appropriately as long as equipment is in place and preparations are made on organizational and engineering levels for advanced utilization.” In other words, the most important lesson learned after the Fukushima Daiichi accident is that we need to gain social trust about the feasibility of severe accident prevention (“the protection of the living environment of the public or social protection,”) in addition to the conventional safety objective of “protecting the public from the risk of radiation hazards.”

To this end, it is not enough if mandatory safety regulations by the government are stringent. Rather, it is necessary for the industrial and academic parties concerned with the development and use of nuclear energy to take on the practical challenge of safety culture, or I should say “the Way of Safety,” in which they will voluntarily pursue the way to ensure safety with “INTEGRITY” and strong perseverance. This also involves important challenges of not only upgrading and enhancing components and systems, but also reinforcing human characteristics, i.e. personal and organizational characteristics (e.g. leadership, organizational effectiveness, resilience, effective governance, information sharing, foresight, insight, performance capability, and use of field experience). We must decisively improve INTEGRITY we lacked in the past development and use of nuclear energy in Japan.

end(Written on July 28, 2013)

[note]:JANSI have translated p.479 in September issue of ATOMO∑(the Magagine of Atomic Energy Society of Japan)