Focus on the 60th anniversary of the Kyshtym Accident and the Windscale Fire

The full text of the Invited Editorial is given in the PDF file.

A serious fire developed in the core of a nuclear reactor at Windscale Works, Sellafield, northwest England, which led to the release of significant quantities of radioactive material into the environment during 10–11th October, 1957. In 1957, Windscale Works was operated by the United Kingdom Atomic Energy Authority (UKAEA), and on 15th October it was announced by the Chairman of the UKAEA that a Committee of Inquiry had been established under the chairmanship of Sir William Penney to conduct an investigation into the accident. The Committee sat at Windscale Works during 17–25th October, interviewed 37 people (some more than once), and examined 73 technical exhibits. The Committee reported to the Chairman of the UKAEA on 26th October. The Report of the Committee formed the technical basis of a UK Government White Paper (Cmnd. 302) published on 8th November, 1957, but the Penney Report itself was not published, and was only made public (at what is now The National Archives, TNA, Kew) in January, 1988. The original Report of the Committee of Inquiry is reproduced here from a copy of the Report supplied by TNA from TNA File AB 86/25.

This paper presents an overview of the nuclear accident that occurred at the Mayak Production Association (PA) in the Russian Federation on 29 September 1957, often referred to as 'Kyshtym Accident', when 20 MCi (740 PBq) of radionuclides were released by a chemical explosion in a radioactive waste storage tank. 2 MCi (74 PBq) spread beyond the Mayak PA site to form the East Urals Radioactive Trace (EURT). The paper describes the accident and gives brief characteristics of the efficacy of the implemented protective measures that made it possible to considerably reduce doses to the exposed population. The paper also provides retrospective dosimetry estimates for the members of the EURT Cohort (EURTC) which comprises approximately 21 400 people. During the first two years after the accident a decrease in the group average leukocyte (mainly due to neutrophils and lymphocytes) and thrombocyte count was observed in the population. At later dates an increased excess relative risk of solid cancer incidence and mortality was found in the EURTC.

The experience accumulated while dealing with the aftermath of a major nuclear accident (the 'Kyshtym Accident') in 1957 at the Mayak complex in the Southern Urals of Russia is summarised. Information is presented on the causes of the accident, on the radiation environment and radioactive contamination of the affected territory in the critical period, and on the system of emergency management and decision-making adopted when dealing with the accident and its aftermath. The technical and organisational approaches applied and methods used are described, as well as remediation results and the current situation 60 years after the accident. It is demonstrated that the implementation of fairly simple and self-evident organisational and technical solutions gave good results, and that appropriate timely and task-oriented measures were applied. Safety relevant conclusions and recommendations are presented.

The full text of the Invited Editorial is given in the PDF file.

During 10–11 October 1957 a fire in the core of a nuclear reactor at Windscale Works, Sellafield (in the current county of Cumbria, England) led to a significant release of radioactive material to atmosphere. The accident at Windscale No. 1 Pile required a large-scale environmental monitoring programme to be conducted and the results of this survey led to a restriction on the distribution of milk from an area adjacent to Windscale Works for a period of several weeks. This monitoring programme was described in detail by H J Dunster and his colleagues from the Industrial Group of the United Kingdom Atomic Energy Authority (which operated Windscale Works in 1957) in a paper presented to the Second United Nations International Conference on the Peaceful Uses of Atomic Energy, held in Geneva during 1–13 September 1958. The paper, from the proceedings of this conference, is reproduced here.

The original reference of this paper is: Dunster H J, Howells H and Templeton W L 1958 District surveys following the Windscale incident, October 1957 Proceedings of the Second United Nations International Conference on the Peaceful Uses of Atomic Energy (Geneva, 1 September–13 September 1958). Volume 18: Waste Treatment and Environmental Aspects of Atomic Energy (Geneva: United Nations) pp 296–308

The paper is reproduced with the kind assistance of the United Nations, and of Mrs Rose Dunster, the widow of Mr H John Dunster.

The full text of the book reviews in this issue is given in the PDF file.

The mortality and cancer morbidity experience of the 470 male Sellafield employees known to be involved in the 1957 Windscale accident is reported. All these employees are known to have been involved in dealing with the fire itself, or in the clean-up operation afterwards. The size of the study population is small, leading to predicted low power to reveal any effects, but the cohort is of interest because of the involvement of the workers in the accident. For 1957-97, using rates for England and Wales to calculate the expected numbers, the all causes standardised mortality ratio (SMR) is 100 (observed=258, expected=258.80), and the all malignant neoplasms SMR is 79 (observed=58, expected=73.12) which is not significantly different from 100. For 1971-91, the all malignant neoplasms standardised registration ratio (SRR) of 85 (observed=59, expected=69.23) is not significantly different from 100. Significant excesses of deaths from diseases of the circulatory system (SMR=121) and from ischaemic heart disease (SMR=128), and a significant deficit of deaths from cancer of the genito-urinary organs (SMR=31), were found. There were no significant differences in mortality rates between workers who had received high recorded external doses during the fire and those who had received low doses, though the power of this comparison was low. Comparison of the mortality rates of workers directly involved in the accident with workers in post, but not so involved, showed no significant differences. This study has been unable to detect any effect of the 1957 fire upon the mortality and cancer morbidity experience of those workers involved in it.

On the 3rd October 1957, after a virtuoso speech by Aneurin Bevan, the Labour Party Conference voted against British renunciation of the H-bomb. On the 4th, the Soviet Sputnik I - the first man-made satellite to orbit the Earth - astonished and alarmed the Western world. On the 9th, Britain's last atmospheric A-bomb test took place in Australia. From the 10th to the 12th, fire in Windscale's Pile Number 1 threatened catastrophe. An epidemic of Asian flu swept through England and Wales.

From those ten memorable days the event most often remembered must be the Windscale accident. It is for me. When I read David McGeoghegan's and Keith Binks' paper (page 261 of this issue) it was another interesting reminder of topics that have recurred in my life for the past 40 years - Windscale, radiological protection and epidemiology.

When I joined the UK Atomic Energy Authority in January 1959, the 1957 accident still loomed hugely, especially for the new Authority Health and Safety Branch (AHSB) to which I was recruited. My first job there was as joint secretary of a committee on training in radiological health and safety, which had been set up as a result of the accident. It was not easy for a newcomer with no scientific background, but it was an immense privilege to meet such remarkable men as Sir Ernest Rock Carling and Professor Val Mayneord each week. And I was most fortunate to work for the UKAEA's first Director of Health and Safety, the wise and witty Dr Andrew McLean, who as Chief Medical Officer at Risley, had been much involved in all the health aspects of the accident.

As Director of Health and Safety, one of his concerns was to provide the UKAEA with the best possible, unified, system of health records. Apart from its management value, and its importance for public accountability and public relations, he was well aware of how essential it would be in the long term for epidemiological studies. At Risley, he had been able to coordinate and rationalise health records in the northern establishments. But the UKAEA was a highly decentralised organisation; various establishments had their own idiosyncratic methods of record keeping, and resisted change. Objections were raised, too, to the alleged costs of a unified system. Patience and persuasion prevailed, and by the mid-1960s Andrew McLean and his colleague, Ken Duncan (the UKAEA Chief Medical Officer), developed and put in place a system which was up to the highest standards of major industrial organisations of the period.

I remember once asking him whether a special life-time study might not be undertaken of the 470 men who had been engaged in the fire and the clean-up operation because, though only a small group, they had the advantages of being easy to follow up and of having good radiation records. As I remember, this was regarded as inadvisable, or even impossible, as it might cause harmful and unnecessary anxiety to the people concerned; nor could they be followed up after they left UKAEA employment, without an invasion of privacy. Now it is all here in McGeoghegan's and Binks' fascinating retrospective study.

I was transferred from the AHSB to the UKAEA history office in 1967, but the Windscale accident was not left behind for long. A two-volume history of 'Britain and atomic energy 1945-1952' was published in 1974, and work then began on the sequel (1952-1958). A chapter on the Windscale accident was assigned to me to write. I did a good deal of work on it, and interviewed many of the people involved. However, as it turned out, the 1952-1958 book was never completed or published. But the work was not altogether wasted, for some of the interviews I did then, and saved, would have been impossible in the 1980s.

The Windscale accident again came to the fore when the Chernobyl disaster in 1986 renewed public interest in reactor accidents. Nearer to home, the date was approaching (January 1988) when UKAEA and other official files about Windscale 1957 would be opened in the Public Record Office, and much media interest and publicity were likely. After a thorough study of all the relevant papers I suggested a book might be useful. It was agreed and the result was my Windscale 1957: Anatomy of a Nuclear Accident, first published in 1992.

There is so much to remember and reflect on, but I will conclude with just two comments. First, there is still more to learn about the accident, and various studies are, I know, ongoing. One significant event can yield new information and insights for many years, especially as new and more powerful analytical tools become available. This is true, a weapons scientist told me, of nuclear weapon tests, provided there are good records. The same is perhaps even truer of an event like the Windscale accident, in which the passage of time (as well as improved analytical methods) is so important in epidemiology.

Second, I am very conscious, as I read this study of morbidity and mortality, that I am seeing the outcome not of present radiological standards and methods of protection but of those that obtained decades ago. These results are a testimony to the work of post-war health physicists, and to the vital influence of ICRP - refounded in 1950 largely on the initiative of Rock Carling and Mayneord. With daunting practical questions crying out for answers, and little research material to draw on, ICRP gave sound and far-sighted advice for the new atomic age. The world has moved on, but we have good reason to remember the wise men of the 1950s with admiration and gratitude.

This paper studies the mortality and cancer morbidity of the 470 male workers involved in tackling the 1957 Sellafield Windscale fire or its subsequent clean-up. Workers were followed up for 50 years to 2007, extending the follow-up of a previously published cohort study on the Windscale fire by 10 years. The size of the study population is small, but the cohort is of interest because of the involvement of the workers in the accident. Significant excesses of deaths from diseases of the circulatory system (standardised mortality ratio (SMR) = 120, 95% CI = 103–138; 194 deaths) driven by ischaemic heart disease (IHD) (SMR = 133, 95% CI = 112–157, 141 deaths) were found when compared with the population of England and Wales but not when compared with the population of Northwest England (SMR = 105, 95% CI = 90–120 and SMR = 115, 95% CI = 97–136 respectively). When compared with those workers in post at the time of the fire but not directly involved in the fire the mortality rate from IHD among those involved in tackling the fire was raised but not statistically significantly (rate ratio (RR) = 1.11, 95% CI = 0.92–1.33). A RR of 1.11 is consistent with an excess relative risk of 0.65  Sv ^{− 1} as reported in an earlier study of non-cancer mortality in the British Nuclear Fuels plc cohort of which these workers are a small but significant part. There was a statistically significant difference in lung cancer mortality (RR = 2.18, 95% CI = 1.05–4.52) rates between workers who had received higher recorded external doses during the fire and those who had received lower external doses. Comparison of the mortality rates of workers directly involved in the accident with workers in post, but not so involved, showed no significant differences overall. On the basis of the use of a propensity score the average effect of involvement in the Windscale fire on all causes of death was − 2.13% (se = 3.64%, p = 0.56) though this difference is not statistically significant. The average effect of involvement in the Windscale fire was − 5.53% (se = 3.81, p = 0.15) for all cancers mortality and 6.60% (se = 4.03%, p = 0.10) for IHD mortality though neither figure was statistically significant.

This analysis of the mortality and cancer morbidity experience of those Sellafield workers involved in the 1957 Windscale fire does not reveal any measurable effect of the fire upon their health. Although this study has low statistical power for detecting small adverse effects, due to the relatively small number of workers, it does provide reassurance that no significant health effects are associated with the 1957 Windscale fire even after 50 years of follow-up.

The Windscale nuclear reactor fire at Sellafield, United Kingdom, in October 1957 led to an uncontrolled release of iodine-131 (radioactive half-life, 8 d) into the atmosphere. Contamination from the accident was most pronounced in the counties of Cumbria and Lancashire, north-west England. Radioiodine concentrates in the thyroid gland producing an excess risk of thyroid cancer, notably among those exposed as children, which persists into later life. For an initial investigation of thyroid cancer incidence in north-west England, data were obtained on cases of thyroid cancer among people born during 1929–1973 and diagnosed during 1974–2012 while resident in England, together with corresponding populations. Incidence rate ratios (IRRs), with Poisson 95% confidence intervals (CIs), compared thyroid cancer incidence rates in Cumbria and in Lancashire with those in the rest of England. For those aged  <20 years in 1958, a statistically significantly increased IRR was found for those diagnosed during 1974–2012 while living in Cumbria (IRR  =  1.29; 95% CI 1.09–1.52), but the equivalent IRR for Lancashire was marginally non-significantly decreased (IRR  =  0.91; 95% CI 0.80–1.04). This pattern of IRRs was also apparent for earlier births, and the significantly increased IRR in Cumbria extended to individuals born in 1959–1963, who would not have been exposed to iodine-131 from the Windscale accident. Moreover, significant overdispersion was present in the temporal distributions of the IRRs, so that Poisson CIs substantially underestimate statistical uncertainties. Consequently, although further investigations are required to properly understand the unusual patterns of thyroid cancer IRRs in Cumbria and Lancashire, the results of this preliminary study are not consistent with an effect of exposure to iodine-131 from the Windscale accident.