Nuclear Accidents

7General Conclusions

7.1. The probability of military and civil accidents

Major accidents in nuclear reactors are rare, but the consequences are catastrophic. There are many causes of nuclear accidents, but their main cause is often human error due to misinterpretation of the warning signals of an accident.

7.1.1. Nuclear risks and probabilities

Major nuclear accidents are caused by fusions of the reactor core. Based on past accidents, the core meltdown frequency is 11/14,400, or 7.6 × 10^-4, or one accident every 1,300 years per reactor. However, the order of magnitude advanced in probabilistic safety assessments is between 10^-4 and 10^-5, or one accident per reactor every 10,000–100,000 years. Compared to an accident every 1,300 years, a factor of 10–100 separates the calculated probabilities from the observed probability. Bishop [LÉV 13a] wondered about the reasons for such a gap. He believes that there are four possible reasons, good and bad, trivial and complicated. These four reasons are bad luck, incompleteness, that each event is unique and that bad settings and models are retained.

The highest nuclear risks concern the major American cities such as New York, Washington, Atlanta, Toronto, Asian cities such as Shanghai, Hong Kong, Tokyo and Osaka, as well as Western Europe given the proximity of many nuclear reactors.

Moller and Mousseau [MØL 13c] have drawn up a list of difficult questions that they address to the authorities. Why are nuclear reactors often grouped ...