Ron Smith: The Significance of Chernobyl

Whenever the subject of civilian nuclear power arises, we sooner or later come to Chernobyl. For some this is the rhetorical equivalent of playing the ace. To mention the events of April 26, 1986, is taken to end all serious debate on the desirability of nuclear power as an energy source. But the reality is (to continue the metaphor) that it is a cheap ‘trick’.

There are a number of factors in the Chernobyl accident which make it an unreliable guide for future risk and there is a persistent and wilful misrepresentation of the actual consequences, which makes discussion of the events and their significance very difficult. And it is not as if there is any shortage of reliable data. ‘Chernobyl’ has been the subject of numerous official studies and reports, including those of the internationally-convened Chernobyl Panel and the World Health Organisation’s International Agency for Research on Cancer.

The key event at Chernobyl was a loss of control of reactor-temperature, which resulted in a structural breakdown and the release of large amounts of radioactive material. Two factors were crucial. The first was an apparent desire on the part of the local operatives to ‘experiment’ with control parameters, an activity which was thwarted by automatic safety mechanisms. The operators responded to this by disabling these mechanisms. The consequence of this was that, once the over-heating began they could not control it. The second factor concerned the design of the plant and, particularly, that it had no containment structure. Most reactors at the time and all modern reactors have such a structure, the function of which (as its name suggests) is to prevent the release of radioactive material in the event of malfunction. This is just what happened in the case of a similar event in the United States (Three Mile Island, 1979) where there was a partial core meltdown. In this case, no significant radioactive matter escaped at all and there were no health consequences.

Nearly twenty years after the events of April 1986, a panel of 100 experts from a variety of international agencies, including the World Health Organisation, the International Atomic Energy Agency and the United Nations Environment Programme, reported the conclusions of an extensive investigation (The Chernobyl Panel, September 2005). In this they give a figure for the number of deaths directly attributable to the accident. The total is 59: made up of 50 of the heroic recovery workers, who attempted to limit the effects of the disaster in the immediate aftermath; and 9 deaths from thyroid cancer, caused by the dispersal of radioactive iodine and a consequence of the vulnerability of children to this particular radio-isotope. The Panel also refer, somewhat speculatively, to ‘perhaps as many as 4,000 of the afflicted population in the region who might ultimately die as a consequence’.

On the other hand, the panel noted that there had been no observed rise in the incidence of leukaemia (a blood cancer associated with radiation exposure) and no detectable decrease in fertility or increase in birth defects. Indeed they concluded that that the largest public health problem unleashed by the accident was ‘the mental health impact’. Residents of the region were said to view themselves as victims of a tragedy they poorly understand and are ‘still haunted by an unfounded anxiety that has prevented many from restarting their lives’.

The Chernobyl Panel report also referred to the extensive exclusion zone, around Chernobyl, which had housed workers and their families before the accident. Of this, it was said that the actual radiation levels were within the variation in natural radiation around the world and lower than inhabited areas of China, Brazil, Britain and the United States. The Chernobyl exclusion zone may be an interesting experiment in what happens when nature retakes what man has wrought but it may not be strictly necessary on health grounds. On the other hand, it does seem as if it is a boon to the tourist and documentary industries.

As noted above, the Chernobyl Panel considered the possibility of long-term health effects over a much wider region of western-Russia and the Ukraine, as well as many parts of Europe in which elevated levels of radiation were detected. In April 2006 the WHO International Agency for Research on Cancer (IARC) reported on this.

Their findings were based on the assumption that there is no level below which exposure to radiation has no effect (the so-called Linear No-Threshold Hypothesis) so that a steady relationship between the ‘dose’ of radiation and the development of cancer is maintained even at very low ‘doses’. It is merely that the proportion of the exposed population that manifests the effect gets smaller and smaller. On this basis IARC projected that over the eighty years from 1985 to 2065 there might be 16,000 fatal cancers attributable to the Chernobyl event. They go on to comment that this would be 0.008% of the ‘natural’ rate over the period and thus will be undetectable in a population of 570 million with an expected 120 million deaths from cancer over the period. Detectable or not, this is the category of persons ‘who might ultimately die’, to which the Chernobyl Panel Report referred.

Chernobyl is by far the worst accident in the history of civilian nuclear power generation (which is now some sixty years). In the nearly quarter of a century since it happened, the technology has moved on in both safety and efficiency. It is hardly likely to happen again. It is also worth noting that the deaths directly attributable to this event are a fraction of those associated with the major competitive power-generation technologies (Coal, Oil, Gas, and Hydroelectric power). If we are thinking of the place of civilian nuclear power in the world today, Chernobyl is interesting history but it has little relevance for our decision-making. Rather, we should be thinking more of cost, reliability of supply and environmental impact. If we do this we might find that nuclear power stacks up rather well.