Bulletin ^ Vienna, Austria Quarterly Journal of the International Atomic Energy Agency
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Jal VOL.38, N0.3 /// 1996 BULLETIN ^ VIENNA, AUSTRIA QUARTERLY JOURNAL OF THE INTERNATIONAL ATOMIC ENERGY AGENCY TCHERNOBYL: MISE EN PERSPECTIVE riEPCriEKTHBbl HEPHOBblflfl CHERNOBIL EN PERSPECTIVA X X X X X X X Ì X X Front Cover: Just over ten years after the world's tragic nuclear IAEA i plant accident at Chernobyl, how much have we learned about its BULLETIN actual consequences? The scientific and technical answers are QUARTERLY JOUHMAL of ATOMIC ENEHQV AGENCY many and cover much ground and an array of complex topics. Fortunately, as the accident's long shadows recede and myths unravel, perspectives sharpen. Through global efforts, more light is being shed on the accident's true effects, and the needs of its victims. While open issues still must be resolved, a factual framework was set in April 1996 at the International Chernobyl Conference in Vienna to support decisions — especially those affecting the millions of men, women, and children living in the towns, villages, and farms most in need of assistance. (Cover design: Hannelore Wilczek, IAEA; Stefan Brodek, Vienna.) Facing Page: Women greet experts of the I990 International Chernobyl Project, one of many global studies that has examined post-Chernobyl social, health, and environmental effects in parts of Belarus, Russia, and Ukraine. (Credit: Mouchkin, PavlicekJ IAEA). CONTENTS Features Chernobyl — Ten years after by Abel J. Gonzalez 12 One decade after Chernobyl: The basis for decisions Highlights of the International Chernobyl Conference and its results 114 Special Reports Post-Chernobyl scientific perspectives: Social, health, and environmental effects Environmental consequences, report by Mona Dreicer and Rudolf Alexakhin 124 Social!psychological effects, report by Britt-Marie Drottz-Sjoberg, G.M. Rumyantseva, A.I. Nyagu, and L.A. Ageeva I 27 Clinically observed effects, report by Gerard Wagemaker, Angelina K. Guskova, Vladimir G. Bebeshko, and Nina M. Griffiths 129 Thyroid effects, report by E.D. Williams, A. Pinchera, D. Becker, E.P. Demidchik, S. Nagataki, andN.D. Tronko 131 Health effects, report by Fred A. Mettler /33 Long-term health effects, report by E. Cardis, A.E. Okeanov, V.K. Ivanov, and A. Prisyazhniuk I 36 Agricultural countermeasures, report by John I. Richards and Raymond J. Hance I 38 Nuclear safety aspects, report by Luis Lederman 144 Bulletin Update Inside Technical Co-operation: Nuclear Energy for the Environment /Insert Departments International Newsbriefs/Datafile / 48 Posts announced by the IAEA / 56 Keep abreast with IAEA publications / 58 Authors and Contributors to 1995 IAEA Bulletin / 60 Databases on line / 62 IAEA conferences and seminars/Co-ordinated research programmes / 64 ISSN 0020-6067 IAEA BULLETIN, VOL. 38, NO. 3 (SEPTEMBER 1996) FEATURES Chernobyl — Ten years after Global experts clarify the facts about the 1986 accident and its effects by n 26 April 1986, a catastrophic explosion at international conference on One Decade after Abel J. González OUnit 4 of the Chernobyl nuclear power Chernobyl: Summing up the Consequences of plant in the Ukrainian Republic — close to the the Accident, held at the Austria Center in point marking the three-way border with the Vienna. The Chernobyl Conference was a Republics of Belarus and Russia — sent a very model of international co-operation: six organi- large amount of radioactive material into the zations of the UN family, including the IAEA, atmosphere. The event was to become one of the and two important regional agencies were most protracted and controversial themes of the involved in its organization. (See boxes on pages modern technological era. The Chernobyl acci- 8 and 17.) dent caused widespread concern over its radio- Between the accident in 1986 and this logical consequences, and also focused attention Chernobyl conference, the IAEA participated in on nuclear safety generally. The accident's a range of scientific endeavours which sought to aftermath evolved together with the unfolding quantify the actual consequences. (See boxes on of glasnost and perestroika in the former USSR pages 5,6,7 and 8). and soon became bound up with many misun- The aim of the Chernobyl Conference was to derstandings and apprehensions about the consolidate "an international consensus on the radioactive release and its real or perceived accident's consequences, to agree on proven sci- effects. entific facts, and to clarify information and There was initial secrecy and confusion prognoses in order to dispel confusion". The about the accident — candidly reported in Prof. results of the Conference speak for themselves. Leonid Ilyin's book, Chernobyl: Myths and (See the following article for Highlights of the Reality. The people living in the affected areas Chernobyl Conference: Summary of Results). learned about the event mainly from hearsay Some important issues have been summarised rather than from authoritative reporting. The here and are separately analysed in reports fea- first evidence of the accident outside the USSR tured in this edition of the IAEA Bulletin. resulted from measurements in Nordic countries Radioactive fallout. Although even today showing an unexpected increase in environmen- there is no complete consensus on the amount of tal radioactivity. This initial lack of transparen- radioactive material released by the Chernobyl cy had an impact on public confidence, and sub- accident, the best estimates — which are of the sequently so did the confusing and at times con- magnitude of 10 international units of activi- tradictory nature of the information released. ty, called becquerels — are illustrative of the Perceptions of the catastrophe ranged from catastrophic nature of the accident. Two chemi- those who believed that Chernobyl had been one cal elements in the radioactive plume formed by of the world's worst ever disasters to those who the materials released dominated the radiologi- saw it as a relatively limited health problem cal consequences: iodine and caesium. There is despite the tragic circumstances. a family of mainly short-lived radioactive iso- A decade later, in April 1996, more than 800 topes of iodine: a significant one is iodine-131. experts from 71 countries and 20 organizations whose activity falls by half every eight days. — observed by over 200 journalists — met to Radioiodines were mainly responsible for irradi- review the Chernobyl accident's actual and pos- ation of the thyroid gland of the people living in sible future consequences, and to put these into nearby regions shortly after the accident. Of the proper perspective. They came together at the radioactive caesiums, the most significant is cae- sium-137. a long-lived nuclide whose activity falls by half every 30 years. Caesium-137 was Mr. González ¡s Director of the IAEA Division of Radiation and Waste Safety, Department of Nuclear Safety. transported through the atmosphere for long dis- IAEA BULLETIN, 3/1996 FEATURES Release of radioactive material into the environment 1 Q he destroyed reactor released a very large amount of radioac- About 10 becquerels of iodine-131 were released by the acci- Ttive material into the environment: lCr" international units dent. Iodine is mainly absorbed by a person's thyroid gland after of activity, termed becquerels. Although the discharge included inhalation or after consumption of contaminated foodstuffs such many radioactive chemical elements, just two of them — iodine as milk products; its short range beta particles irradiate the gland (in the short term) and caesium (in the long term) — were par- from the inside. Uptake of iodine by the thyroid is very easy to ticularly significant from a radiological point of view. prevent, for example by banning consumption of contaminated food for a few weeks until the iodine-131 decays sufficiently or by administering small amounts of non-radioactive iodine prophylactically to block the thyroid gland. About 10' ' becquerels of radioactive caesiums were released, and precipitated over a vast area (see map MEPHOBblilbCKMM flPOEKT on page 5). Exposure to caesium is difficult to pre- 3KCnEPTH3A PAAHOJIOTHMECKHX vent. Once it is deposited in the soil, its long range H OL4EHKA 3AtHHTHblX gamma rays can expose anybody in the area. To clean UTOrOBAfl EPOWIOPA the surfaces is difficult and, if the concentration of caesium is high, often the only feasible countermea- sure is to evacuate the inhabitants. Caesium in the soil can also be transferred into agricultural products and grazing animals. For iodine-131, there is no clear information on where the release went, who was exposed to it and to which levels, or whether iodine uptake was effective- ly prevented. Indirect estimations gave firm indica- tion that very high thyroid doses were incurred by some population groups. Children, who are particu- larly sensitive because of their normally high inges- tion of milk products and their small thyroids, received higher doses. In 1990 the International Chernobyl Project (see box, page 7) had predicted that, with high doses, a signif- icant increase in the incidence of the relatively rare cancer of the thyroid would occur in affected children after a few years. The cover of the Russian edition of a booklet describing the International Chernobyl Project, which was conducted by teams of international scientists in 1990 and 1991. tances, deposited variably over vast areas, mainly sequences for people and ecosystems in and in Europe and — to a minor but measurable near the Chernobyl plant site. Radiation damage extent — elsewhere over the whole northern correlates with the radiation dose incurred by hemisphere. The deposited caesium became the people and biota. Dose is a quantity related to main cause of whole body radiation exposure in the amount of radiation energy absorbed by the the long term. (Sec box above and map on pai>e 51. mass of biological matter. The dose incurred by Radiation doses. The release of radioactive people is expressed in Sieverts and. most com- material was expected to have severe direct con- monly, in the submultiple millisieverts — one IAEA BULLETIN, 3/1996 FEATURES Environmental damage.