International Nuclear Emergency Exercises (INEX)

    The INEX series of international nuclear emergency exercises, organized under the OECD Nuclear Energy Agency's (NEA) Working Party on Nuclear Emergency Matters (WPNEM), have proven successful in testing, investigating and improving national and international response arrangements for nuclear accidents and radiological emergencies. Previous INEX exercises focused largely upon national and international aspects of early phase management of nuclear power plants emergencies. The NEA's work on International Nuclear Emergency Exercises began with the INEX-1 Exercise in June 1993.


    Based on the experience of INEX-1 and its associated workshops, it was agreed that a second, more realistic exercise should be developed and sponsored by the NEA. INEX-2 used as its basis a national-level emergency exercise at an existing power plant. In order to investigate the various international aspects of accident planning, preparedness and management, three exercise objectives were added to the national-level exercise:

    • Decision-making based on limited information and uncertain plant conditions;
    • Use of real time communications with the actual equipment and procedures; and
    • Public information and interaction with media.

    Other countries were invited to participate using their actual hardware, software, procedures and facilities as if it were an actual emergency. Countries then received and collected accident information, performed accident situation analyses and made decisions in real time.

    To allow several different countries in different geographical areas to "host" INEX-2, it was agreed to hold four regional exercises roughly equally spaced in time between mid-1996 and early 1999. For each of these regional exercises, an "accident host" country proposed to use a previously planned and scheduled national-level command-post exercise as a platform for the INEX-2 objectives. Other participating countries activated their own emergency command posts and used existing bilateral and multilateral notification and communication agreements, as well as such agreements with international organisations (IAEA and EC), to receive and transmit information. Only the information gathered through these normal channels were used as the basis of decision-making (countermeasures, public information, data management, etc.). Four exercises were held:

    Exercise Date Nuclear Power Plant
    Swiss INEX-2 November 1996 Leibstadt (BWR)
    Finnish INEX-2 April 1997 Loviisa (PWR)
    Hungarian INEX-2 November 1998 Paks (PWR)
    Canadian INEX-2 April 1999 Darlington (CANDU)

    Early on during the Swiss and Finnish exercises (INEX-2), it became clear that in an emergency situation more information than is currently available would be necessary to ensure that decisions and public information were based on appropriate knowledge. The existing procedural and technological means for information and data transmission were shown to be in need of improvement and modernisation.

    To address these concerns, three working groups were established in order to prepare a coherent strategy to:

    • Better identify key emergency data;
    • Improve emergency communication and information management; and
    • Improve emergency monitoring strategies.

    The results of this work are summarised in the report Monitoring and Data Management Strategies for Nuclear Emergencies. The objective of this new strategy is to assist the decision maker by improving the selection of the data which is being transmitted, the transmission and reception of data and information using modern communication methods, (e.g. secure internet technologies), and by defining emergency monitoring and modelling needs.

    Many NEA Member countries, the European Commission and the International Agency Energy Agency are implementing this strategy. Other countries and international organisations (the World Health Organization, World Meteorological Organization, and the United Nations Office for the Coordination of Humanitarian Affairs) are considering how best to adapt the strategy to their roles and needs.


    The NEA's work on International Nuclear Emergency Exercises began with INEX-1 in June 1993. The objective of this exercise was to identify important policy issues and areas where transboundary communication and co-ordination could be improved. An important issue here was the intervention levels which had been adopted by various countries, and how the implementation of countermeasures was co-ordinated, particularly in border regions.

    An assessment of INEX-1 results revealed three areas for further work. To address these issues, three workshops were held, between 1994 and 1996:

    • The implementation of short-term countermeasures after a nuclear accident;
    • Agricultural aspects of nuclear and/or radiological emergency situations;
    • Nuclear emergency data management.

    Based on the experience from INEX-1 and from the three follow-up workshops, a more realistic international nuclear exercise was launched. INEX- 2 was planned as a series of regional, command-post exercises with the voluntary and simultaneous real-time participation of many countries. The objectives of this exercise series focused on the real time exchange of information, public information and decision making based on limited information and uncertain plant conditions.

    Related publications and links

    Second International Nuclear Emergency Exercise, INEX-2: Final Report of the Finnish Regional Exercise, NEA, Paris, 2000

    Monitoring and Data Management Strategies for Nuclear Emergencies, NEA, Paris, 2000

    Second International Nuclear Emergency Exercise, INEX-2: Final Report of the Swiss Regional INEX-2, NEA, Paris, 1998

    Emergency Data Management, Proceedings of the NEA Workshop, Zurich, September 1995, NEA, Paris, 1996

    INEX-1: An International Nuclear Emergency Exercise, NEA, Paris, 1995.

    Short-term Countermeasures, Proceedings of the NEA Workshop, June 1994, Stockholm, NEA, Paris, 1995.

    Agricultural Aspects of Nuclear and/or Radiological Emergency Situations, Proceedings of an NEA Workshop, June 1995, NEA, Paris, 1996.

    Last reviewed: 27 October 2010