Nuclear Safety Into the Future

• 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.