J. T. SMITH

ABSTRACT

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: Wind — scale, 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.

Issues in Environmental Science and Technology, 32 Nuclear Power and the Environment Edited by R. E. Hester and R. M. Harrison © Royal Society of Chemistry 2011

Published by the Royal Society of Chemistry, www. rsc. org

1 Introduction

Prior to the 2011 Fukushima accident, there had been four accidents of major importance in terms of their actual or potential consequences for the envir­onment and human health. The two earliest accidents, at the Windscale site in the UK and at Kyshtym in the former Soviet Union, were at facilities which were part of the Cold War drive to produce materials for nuclear weapons production. The latter two, at Three-Mile Island (TMI) in the USA and at Chernobyl, in the former Soviet Union, were at civilian nuclear power plants (see Table 1). Much has previously been written about these four accidents, particularly the Chernobyl accident, and this chapter aims to give a brief summary and overview of this literature.

In addition to these major accidents, there have previously been significant releases of radioactivity to the environment during development of nuclear weapons and from ‘‘routine’’ operations at nuclear facilities. Some key past releases of radioactivity to the environment are summarised in Table 2. It should be noted that long-term environmental contamination from the Hiroshima and Nagasaki bombs was not significant; the high radiation exposures to the population of these cities came primarily from radiations during or shortly after the explosions. During the Cold War, atmospheric (i. e. above ground) testing of nuclear weapons caused fallout of relatively low level radioactivity (particularly 90Sr, 137Cs and 14C) globally, mainly in the Northern Hemisphere. Several hundred atmospheric nuclear weapons tests were carried out by the USA, USSR and the UK until a test ban treaty was signed in 1963. Limited atmospheric nuclear weapons tests were carried out by France and China in the early 1970s.