Nuclear accidents

In the wake of the Fukushima accident, this chapter provides a summary and comparison of the four previous major accidents in the history of exploitation of nuclear power for military and civilian purposes: Windscale, Kyshtym, Three-Mile Island (TMI) and Chernobyl. The events leading to each accident, and their consequences to environmental and human health, are summarised. The earlier accidents at Windscale (UK) and Kyshtym (former Soviet Union) could be attributed in large part to the pressures to produce plutonium for atomic weapons programmes during the early years of the Cold War. This led to nuclear facilities being built with insufficient emphasis on design safety and, in some cases, lack of full understanding of the processes involved. The latter accidents at TMI (USA) and Chernobyl (former Soviet Union) were also in part caused by design and equipment failures, but operator errors (caused by poor training, insufficient or unclear information and a failure in safety culture) made a key contribution. In terms of environmental and human health impacts, the Kyshtym and Chernobyl accidents were of much greater significance than those at Windscale and TMI. Both Kyshtym and Chernobyl caused mass permanent evacuation and significant long-term environmental contamination. As demonstrated at TMI, even where radiation doses to the public are very low, psychological and social consequences of nuclear accidents can be serious. Concerning impacts of nuclear accidents on ecosystem health, there is no clear evidence that even the Kyshtym and Chernobyl accidents have caused significant damage in the long term. However, studies of the effects of radiation damage in these contaminated environments have been confounded by the largely positive impact evacuation of the human population has had on the ecosystem.