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Nuclear Safety Into the Future

Mike Weightman

Mike Weightman, a nuclear safety consultant, was the Chief Inspector of Nuclear Installations and Chief Executive Officer of the United Kingdom’s Office for Nuclear Regulation before his retirement in 2013. He is a member of the International Nuclear Safety Group (INSAG), and was the leader of the IAEA International Expert Fact Finding Mission to Japan in May-June 2011.

It is now ten years since the Great East Japan Earthquake and the associated devastating tsunami that led to the nuclear accident at TEPCO’s Fukushima Daiichi nuclear power plant. Various reports have been produced. Several conferences have been held. A range of detailed analyses and technical investigations conducted. Have we learned enough and implemented lessons sufficiently? What are the main messages from the accident for future generations?

Nuclear power can be a major component in addressing the global problems of clean energy and clean water. But public acceptance of the technology is low in many countries. Why should people believe in it if, some people say, when it goes wrong, it can cause major disruption to societies and harm to people? Society is changing, and fast. Technology is advancing peoples’ lives. What does it all mean for the future of nuclear safety? Do we know?

Main lessons from the Fukushima Daiichi nuclear accident

Lessons from the accident have been listed in several analyses, most authoritatively in The Fukushima Daiichi Accident — the IAEA Director General’s report of 2015. In essence, these lessons fall into two groups — technical and human/organizational — but they should be looked at as part of an overall system, and that in itself is a major lesson.

The technical lessons include:

The main areas where further advances in nuclear safety may be made in the ongoing programme of nuclear operation and development are those in the fields of human and organizational safety.
Mike Weightman, Nuclear safety consultant
  • Having a consistent approach to setting design bases for external hazards based on a precautionary approach to uncertainty;
  • Covering related hazards and multi-plant scenarios in safety analyses and provisions;
  • Providing robust means to ensure fundamental safety functions (containment, control and cooling), including in severe accident scenarios;
  • Providing robust means to monitor reactor and spent fuel safety parameters in severe accidents;
  • Ensuring that off-site emergency monitoring and emergency control centres can work effectively under severe conditions; and
  • Using an all-risk approach to off-site emergency decision-making.

Of course, it can be said that the requirements of existing IAEA safety standards cover such issues, but what matters is whether they are understood, followed and implemented. This requires paying attention to the human and organizational elements of safety, and that is where some of the major challenges lie. Some major lessons observed in this area are:

  • Guarding against complacency and groupthink;
  • Adopting a continuous improvement philosophy;
  • Ensuring nuclear regulators are truly independent;
  • Using a system approach to determining and improving the institutional arrangements for ensuring nuclear safety; and
  • Adhering to IAEA safety standards and other guidance, such as reports 4 and 27 of the International Nuclear Safety Group (INSAG).

The implementation of these lessons has been sparked through a variety of routes: regulators, international institutions, public concerns, countries that have nuclear power plants, and other stakeholders, as well as by, importantly, the nuclear industry itself. These have been chronicled in many places, notably in Implementation and Effectiveness of Actions Taken at Nuclear Power Plants following the Fukushima Daiichi Accident (IAEA TECDOC-1930); reports by the World Association of Nuclear Operators (WANO) and the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development (OECD/NEA); and national, regulatory and utility publications. These lessons have illustrated the many areas where, on the basis of a culture of continuous improvement, changes have been made.

Into the future

Given what has been achieved to date, it is unlikely that any further significant lessons to improve nuclear safety will emerge from the ongoing decommissioning work at Fukushima Daiichi or related work elsewhere. Of course, as the inside of the stricken reactors is surveyed and material recovered and decommissioned, more research will assist in promoting confidence in analytical and severe accident modelling techniques or in enhancing them further.

Further consideration of a balance for optimized risk decisions involving low level radiation exposure will assist in determining emergency arrangements to minimize health and societal detriments.

With the increasing consideration of advanced reactor designs, the opportunity arises to look afresh at instilling a more fundamental approach to nuclear safety, utilizing passive safety philosophy, with less reliance on multiple complex protective systems. Additionally, ongoing research into accident tolerant fuels is potentially an important step forward that could also benefit present nuclear reactor safety.

However, the main areas where further advances in nuclear safety may be made in the ongoing programme of nuclear operation and development are those in the fields of human and organizational safety. In particular, we have to develop a more integrated and systemic approach for establishing and improving nuclear safety institutions to enable future generations to utilize safe and economical nuclear power to address the environmental challenges the world faces. And to do that, we must ensure, and demonstrate, that our hard-won lessons are not lost and, through a humble and responsive approach, earn the trust of a changing society. That is our duty.

To find out more on the implications for nuclear safety in a changing society, see the International Conference on a Decade of Progress After Fukushima-Daiichi: Building on the Lessons Learned to Further Strengthen Nuclear Safety.

March, 2021
Vol. 62-1

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