Calculating nuclear accident probabilities from empirical frequencies


Since there is no authoritative, comprehensive and public historical record of nuclear power plant accidents, we reconstructed a nuclear accident data set from peer-reviewed and other literature. We found that, in a sample of five random years, the worldwide historical frequency of a nuclear major accident, defined as an INES level 7 event, is 14 %. The probability of at least one nuclear accident rated at level ≥4 on the INES scale is 67 %. These numbers are subject to uncertainties because of the fuzziness of the definition of a nuclear accident.

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Fig. 1
Fig. 2


  1. 1.

    The first lines of the INES reference User’s Manual (2008 edition): states “The need for easily communicating the significance of any event…” (Foreword, page v.) and “The International Nuclear and Radiological Event Scale is used for promptly and consistently communicating to the public the safety significance of events associated with sources of radiation” (section 1.1).

  2. 2.

    Since the limits between INES level are fuzzy, accidents rated at level = 3 were also searched for in the research to build the data set. They will be used, in a later study, to allow more specific tests regarding the influence on the results of this study stemming from a fuzzy frontier between different INES levels.

  3. 3.

    Or four major accidents if one considers that 3 major accidents occurred in Fukushima Daichi.


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We acknowledge preliminary research by Arnaud de Myttenaere, ENSAE student intern at CIRED. We thank warmly M. V. Ramana for a careful reading of the manuscript and his valuable comments. All remaining errors are the responsibility of the authors.

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Correspondence to Minh Ha-Duong.

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Ha-Duong, M., Journé, V. Calculating nuclear accident probabilities from empirical frequencies. Environ Syst Decis 34, 249–258 (2014).

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  • Nuclear accidents
  • Frequencies
  • Nuclear power
  • Industrial history
  • Bootstrap
  • INES scale