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' ' ... Cover: The Advanced Gas -Cooled Reactor at Windscale, England. Reproduced by kind permission of the United Kingdom Atomic Energy Authority. WHO Regional Publications European Series No. 3

HEALTH IMPLICATIONS OF NUCLEAR POWER PRODUCTION

Report on a Working Group Brussels, 1 -5 December 1975

WORLD HEALTH ORGANIZATION REGIONAL OFFICE FOR EUROPE COPENHAGEN 1978 ISBN 92 9020 103 7

© World Health Organization 1977 Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol 2 of the Universal Copy- right Convention. For rights of reproduction or translation, in part or in toto, of publications issued by the WHO Regional Office for Europe application should be made to that Office, Scherfigsvej 8, DK -2100 Copenhagen 0, Denmark. The Regional Office welcomes such applications. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or of certain manufacturers' products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. This report contains the collective views of a Working Group and does not necessarily represent the decisions or the stated policy of the World Health Organization.

PRINTED IN DENMARK Note

This report was previously issued for limited distribution under the symbol ICP /CEP 804(1) but some minor editorial amendments have been made. The Thirtieth World Health Assembly in May 1977 endorsed the use of SI units in medicine, and such units will therefore be used in future publications of the World Health Organization. However, the present report was prepared before this resolution was taken, and it contains a few non -SI radiation units. In addition, Fig. 2 (pages 18 -20), which is reproduced from another publication, contains a number of non -metric units. The conversion factors for all of these are given in the tables below.

Non -SI unit SI unit and symbol Conversion factor rad gray, Gy 1 rad = 0.01 Gy curie, Ci becquerel, Bq 1 Ci = 3.7 X 1010 Bq (or 37 GBq, gigabecquerel) rem joule per kilogram, J /kg 1 rem = 0.01 J /kg Correct name and Unit as symbol if different Approximate SI unit and symbol given in from those given conversion Fig. 2 in Fig. 2 factor kwh kilowatt hour, joule, J 1 kW h = 3.6 X 106 J kwh acre square metre, m2 1 acre = 4 047 m2 ton ) 1 ton = 1 016 kg kilogram, kg (or 1 ton = 1.016 t) ( (or tonne, t) MT tonne, t / 1 t = 1 000 kg gal. US gallon, 1 gal (US) = 3.785 X 10 -3 m3 gal (US) cubic metre, m3 (or 1 gal = 3.785 litres) (or litre, I) cu. ft. cubic foot, ft3 1 ft3 = 2.832 X 10 -3 m3 gal. /min. US gallon per cubic metre per second,1 gal (US) /min = minute, m3 Is (or cubic metre 6.309 X 10 -5 m3 /s gal (US) /min per minute, m3 /min) (or 3.785 X 10 -3 m3 /min) (or litres per second or per minute may be used instead) CONTENTS

Page

Introduction 5 1. Conclusions and recommendations 6 2. Health effects of radiation 11 2.1 Somatic effects 12 2.2Genetic effects 13 2.3 Other carcinogenic and mutagenic agents 14 3. The nuclear fuel cycle 16 3.1 Mining, extraction and milling 16 3.2Enrichment 16 3.3 Fuel fabrication 21 3.4Power reactor operation 21 3.5 Fuel reprocessing 21 3.6Waste management 21 3.7Transport 23 4. Health and safety regulations of the nuclear fuel cycle 23 5. Radioactive waste management 26 5.1 Highly active waste from fuel reprocessing 27 5.2 Other highly active solid waste 32 5.3 Medium and low activity solid waste 33 5.4Medium and low activity liquid waste 33 5.5 Discharges into the atmosphere 34 6. Siting and decommissioning of nuclear facilities 36 6.1 Siting 36 6.2Decommissioning 36 7. Accidents in the nuclear fuel cycle 38 7.1 Power plant accidents 38 7.2 Transport accidents 42 7.3 Accidents in fuel reprocessing plants 43 7.4Accidents during disposal of high -level radioactive waste. 43 7.5 Procedures for mitigating the consequences of accidents... . 44 7.6Non -radiationoccupationalaccidentsinnuclear power production 44

3 8. Radiation exposures from normal operation of the nuclear fuel cycle 44 8.1 Construction of installations 46 8.2Mining and milling 46 8.3 Fuel fabrication and enrichment 50 8.4Reactor operation 50 8.5 Fuel reprocessing 51 8.6Transport 52 8.7Waste storage 52 8.8 Decommissioning of nuclear facilities 53 8.9Accidents to nuclear plants 53 8.10 Total radiation exposure from nuclear power programmes and consequent effects 53 9. Environmental effects 54 9.1 Thermal effects 54 9.2Chemical waste 56 10. Proliferation of nuclear explosives, sabotage and terrorism 56 11. Consideration of healtheffects from nuclear and alternative energy production systems 58 11.1Public health effects 58 11.2 Occupational health effects 60 11.3 Radioactivity from plants utilizing fossil fuels 61 11.4 Environmental impacts 61 11.5 Alternative energy production systems 62 11.6 Conclusions 62 12. Public information 63 References 64 Annex IDefinitions of "risk ", "detriment ", and "collective dose" 72 Annex IIParticipants 7

4 INTRODUCTION

The Regional Office for Europe of the World Health Organization, at the request of, and in collaboration with, the Government of Belgium, convened a Working Group in Brussels,1 -5 December 1975, to study, discuss, and appraise the effects of nuclear power industry on man and the environment. One of the reasons for the meeting is the concern of the general public about the safety of nuclear power generation. This report, which is based on the collective knowledge and experience of the members of the Working Group, as well as on the available literature, provides some guidelines for public health authorities. It was not the purpose of the Working Group to express any opinions on the advisability of the construction of nuclear power facilities. The meeting was attended by 19 temporary advisers from 12 European countries and from the USA. Six major disciplines (health administration, health physics, human biology, human genetics, environmental science and technology, and nuclear engineering) and five professional categories (physi- cians, biologists, engineers, physicists and chemists) were represented, thus ensuring a multidisciplinary approach to the discussions. Representatives from five international governmental and nongovernmental organizations were also present. The temporary advisers acted in an individual capacity and not as representatives of their countries or organizations. The Working Group reviewed the experience gained from building and operating nuclear facilities and made estimates of the attendant health risks. The Group also considered estimates of the risks associated with the generation of electrical power from other types of fuel. It was agreed to accept the definition of "risk ", "detriment ", and "collective dose" as given in full in Publication No. 22 of the International Commission for Radiological Pro- tection (ICRP) (see Annex I). The Working Group discussed the magnitude of these risks to the general population and to workers in the nuclear power industry. Attention was focused on:

(a)the radiation risks to man, both somatic and genetic, and the environmental aspects of the nuclear fuel cycle, from the mining of uranium to the final stages of decommissioning a nuclear plant and the storage and disposal of radioactive waste products;

(b) the likelihood and consequences of nuclear and non -nuclear accidents, sabotage, and theft of nuclear material.

The Working Group considered measures to protect the population, (including safety regulations and emergency procedures following an accident);

5 technical and administrative procedures on both the national and international levels; education and training of personnel in the nuclear power industry; and public information. A quantitative evaluation of radiation risks for workers and the general population, as well as non -radiation occupational fatalities in the various stages of the nuclear fuel cycle, was incorporated in a summary table (Table 9) as a function of power output. Dr B. Lindell was elected Chairman, Dr E. Komarov, Vice -Chairman, Dr J. Schubert, Rapporteur, and Dr P. Czerski, Co- Rapporteur. Dr M.J. Suess acted as Scientific Secretary. The conclusions and recommendations of the Working Group are given in section 1 of the report. The programme of the meeting, a list of working documents, and a list of participants are given in Annexes II, III and IV, respectively. On the basis of a preliminary draft drawn up by the Rapporteur and the comments of the members of the Working Group on this preliminary draft, a drafting committee, consisting of Dr Dgiderlein, Dr Lister, and Dr Schubert, prepared a draft final report. The Group members subsequently reviewed this draft, and their comments were taken into consideration by the drafting committee in preparing the final version.

1. CONCLUSIONS AND RECOMMENDATIONS

In their discussions, the members of the Working Group drew upon their collective experience and numerous sources of information in evaluating the health implications, hazards and problems involved in the different stages of the nuclear fuel cycle. They kept in mind public health aspects at national and international levels. Subsequently, they formulated the following conclusions and recommendations regarding the generation of electricity by nuclear power reactors.

1.1 Comparative effects of nuclear and alternative energy sources

Quantitative analyses of the effects of the nuclear power industry on the health and wellbeing of individuals and populations must be assessed in comparison with the corresponding effects of alternative energy sources (present and future). In such assessments, data should be treated on an equivalent basis, i.e., for equal energy output and for the complete cycle of operations. Since knowledge of the health effects of alternative sources of energy (for example, fossil fuels) is generally less precise than that of radiation effects, available information should be critically reviewed and appropriate research conducted on the health effects of alternative energy sources.

6 1.2 Radiation exposure

Radiation exposure of workers in the nuclear power industry is generally kept well within the dose limits recommended by the International Commis- sion for Radiological Protection (ICRP). Future exposure of the general public to radiation from all phases of nuclear power production can remain far below the limits recommended by ICRP. It was anticipated that exposures per megawatt of electricity per year (MW(e)a) in the future can and will be reduced by using the available technology. The Group identified the activities in all phases of nuclear power production which are expected to have health consequences to man. The more important ones are: (1) occupational accidents, not involving radiation, during mining and construction; (2) whole -body radiation exposures of workers in reactor and fuel reprocessing operations; (3) radiation doses to the lungs of uranium miners; (4) the collective radiation dose to the world's population due to the release into the atmosphere of long -lived gaseous radionuclides, particularly from carbon -14 compounds. Technology for the reduction of the release into of carbon -14 and other long -lived radionuclides is being developed, and its use, in due course, should be encouraged. The average radiation exposures to local and global populations from nuclear power production, even at a high level, are low compared with the average levels of exposure from natural sources or medical practices. The annual collective radiation dose to radiation workers in nuclear power plants is greater than that to the general population. Most of the radiation dose to the workers occurs during inspection of structural components, maintenance and repair work. The Group agreed that it was neither acceptable nor desirable that radiation exposure from such activities be reduced by decreasing the frequency of this type of work. Only a relatively small reduction in terms of manrem per MW(e)a may be attainable. Whereas the collective occupational radiation doses per MW(e)a associated with reprocessing plants have been high in comparison with those resulting from the operation of nuclear reactors, there isno reason for accepting this situation. With improved design of reprocessing plants, these higher doses can be reduced to the lower levels attained in reactor operation.

1.3 Genetic -somatic effects and epidemiological needs

After reviewing the various factors involved inexposure to radiation and cancer induction, induced mutation rates, and induction of chromosomal

7 aberrations, the Working Group concluded that a linear relationship still serves best for purposes of radiological protection. Indeed, there is increasing evidence that the use of such a relationship might not overestimate the risk to the degree thought earlier. Current estimates of radiation- induced genetic effects are based on experimental data obtained in mammals, largely under conditions of low dose rate exposure where repair of premutational damage is expected already to have taken place. These experimental data support the concept of linearity in the dose range relevant to radiation protection and give no indication of the presence of a threshold dose. In view of the uncertainties inherent in the use of data from animal experimentation for quantitative prediction of effects in human beings, the importance of continued support for epidemiological studies in human populations with special characteristics was emphasized. It is also important that national health statistics be used, after careful scrutiny, to evaluate possible genetic and somatic effects of radiation and other environmental factors. The development and use of biological monitoring methods (cytological and biochemical) should be encouraged. There is need for continuing international initiative and cooperation in developing such programmes under WHO guidance.

1.4 Radioactive waste

With respect to the storage and disposal of long -lived highly active waste, it was concluded that, although the present practice of using modern, specially designed containers for storing this waste in liquid form had proved safe, long -term safety could be further improved by converting this liquid waste into a solid form. There is a genuine need for further development and testing of processes for this purpose. A number of options are available for the final disposal of this waste, but the lack of any immediate need for deciding and acting upon a method allows time for proper and thorough evaluation of these options. Such evaluations should proceed, but pressures to take rapid decisions that might eventually prove to be premature should be resisted. The management of large volumes of solid contaminated materials, e.g., contaminated equipment, requires continued attention. The dumping of conditioned low -level solid waste into the deep ocean under the control of the Nuclear Energy Agency of the Organisation for Economic Co- operation and Development (NEA /OECD) is at present practised on a small scale in relation to limits now under review by the International Atomic Energy Agency (IAEA). The Group called for the acceleration of acceptance of IAEA recommendations on procedures as requested in the

8 Final Act of the Intergovernmental Conference on the Dumping of Wastes at Sea, London, 13 November 1972 (known as the London Convention) .a The Group discussed the effects on man and the aquatic environment of discharges of radioactive substances into fresh water and the sea. The effects depend on the quantities, nature and conditions of the discharge, particularly on the radionuclides concerned, and the degree of initial and final dilution in the water mass. Particular attention must be given to the possible effects on man through various exposure routes, e.g., food chains, rather than on the possible (temporary) effects on aquatic populations. Itis important to establish the predominant exposure routes to man through bioaccumulation or external radiation before major discharges are made, and to carry out and publish the results of appropriate monitoring programmes. Current and predicted discharges to the marine environment constitute only a minute addition to its total natural levels of radioactivity.

1.5 Chemical waste

The Group discussed the control of non -radioactive chemical waste generated during various stages of the nuclear fuel cycle. Although chemical effluents are controllable, within and outside the plants, available technology may not always be utilized to the best advantage. The control of many non- radioactive chemical effluents is also a public health, environmental and regulatory problem in the conventional chemical industry.

1.6 Thermal effects

The Group discussed various aspects and consequences of the discharge of heated water from nuclear power plants. This discharge is not different in kind from that produced by conventional power plants, except that a nuclear power plant discharges somewhat more heat per unit of energy produced. Since both harmful and beneficial ecological effects may occur, the overall consequences of thermal discharges for any specific reactor location must be carefully assessed.

1.7 Siting

The Group considered various factors which govern the siting of nuclear reactors, including the population density around the reactor. It was emphasized that siting can never be a substitute for sound design, construction and operation.

a The London Convention came into force in 1975 and the IAEA Provisional Definitions and Recommendations were accepted as operative for the purposes of the Convention by the contracting parties in September 1976.

9 1.8Decommissioning Detailed studies are being made on the decommissioning and dismantling of reactors and plants, and several pilot plants have already been decommis- sioned and dismantled without considerable problems. I lowever, such operations inevitably produce large amounts of low- activity waste. The inclusion of a requirement for safe and efficient decommissioning in the planning and design of future nuclear facilities is desirable_

1.9 Accidents The Group saw no reason to dissent from the general conclusions of the safety analyses of nuclear power plants recently carried out in a number of countries. All of these analyses assess the risk to the public from accidents involving releases of radioactivity from the reactor core to the environment to be low. Whereas many small accidents might occur, their impact would be more in terms of loss of generating capacity, financial penalties and emotion, than of physical harm. For the assessment and treatment of possible injury caused by high doses of radiation or by the intake of potentially harmful amounts of radioactive materials, there is a need for planned collaboration of various disciplines (medical, dosimetric, analytical) and the establishment of necessary links with specialist services outside the organization involved, which would vary with the type and severity of injury foreseen. It is important that public health authorities be involved in establishing and reviewing emergency arrangements which would apply following an accident serious enough to involve the evacuation of residents for radiological protection purposes. 1.10 Sabotage and terrorist acts Although thereis no way of obtaining absolute assurance against terrorist thefts of radioactive materials (which might be used for the production of a weapon) or against sabotage of a nuclear plant, any risk to the public from such acts would not contribute substantially above that already existing in contemporary society from other similar threats. Reducing the rate of nuclear power development would not substantially reduce the overall possibility of terrorist threats. However, it is important to continue efforts to minimize the possibility of risk from plutonium diversion and from sabotage against nuclear plants. 1.11 Public information Itis important to keep the public currently and fully informed on the likely consequences of operating nuclear power plants, as well as on

10 comparisons with alternative power production sources. Public health authorities would be expected to participate in the dissemination of such information. Contacts established with the general public should continue after construction of these plants. International organizations should play an important role in the dissemination of information on nuclear energy and should contribute to the general awareness and confidence of the public.

1.12 Inspection and personnel training

In addition to the routine inspections of nuclear operations which are carried out by the operators of the facility, the practice of independent checks should be continued. The education and training of personnel was discussed. Operators and other personnel involved in nuclear reactor operations should be technically capable and stable persons. The competence of operating personnel should at least be maintained at the present level.

2. HEALTH EFFECTS OF RADIATION

The biological effects of ionizing radiation on organisms are described in numerous publications, including handbooks on radiobiology, monographs, and compilations such as those in references1and2.Radiation can produce harm when arising from sources outside the body or originating from radioactive isotopes deposited within the body(1,2,3,4,5).The acceptable levels to man of individual radionuclides are based not only on calculations of dose delivered, but on well -established data derived from human epidemiological surveys and on relatively high doses given to experimental animals. Radiation can cause acute (short-term) or long -term health effects. The acute effects are manifested immediately or within daysor weeks following exposure. The long -term effects are not manifested before many years after the radiation exposure. There are several types of long -term effects, including malignant diseases in the exposed individual, abnormal development following irradiation of the foetus (somatic effects), and inherited abnormalities in the descendants of the exposed individuals (genetic effects). There is no evidence at low doses of any life shortening inman from causes other than the induction of fatal malignant diseases. The frequency with which long -term effects may be induced per unit dose of radiation has been estimated, including those resulting from nuclear power programmes, on the basis of a substantial body of experimental and epidemiological data (e.g., references2, 5, 6, 7).

11 2.1 Somatic effects When whole -body radiation is delivered in a short period of time (minutes or hours), the dose of radiation which could kill 50% of the persons irradiated (the LD 50) has been estimated at 250 -450 rad. However, these acute effects would only occur in case of highly unlikely accidents (see Section 7). In normal circumstances, radiation exposures (controlled in accordance with internationally accepted protection standards) amount to at most a few rad per year. Under these circumstances the main somatic radiation hazard, apart from that to the embryo, is the induction of malignancies, including leukaemia. At very low doses, itis cautiously assumed that the risk of cancer induced is simply (linearly) proportional to radiation dose. Estimates can thereby be made of the maximum likely risk of a fatal or non -fatal cancer being induced by applying this dose /risk relationship to the estimated average irradiation of populations (such as might result from nuclear power production) from both more or less uniform irradiation of the whole body and from local organ exposures. Observations on the effects of radiation in humans have been made in follow -up studies on persons who have received radiation for medical diag- nostic or therapeutic purposes, studies of survivors of the attacks on two Japanese cities(8),epidemiological studies on populations in areas of high natural background radiation(9,10,11,12,13)and on groups of persons exposed in the course of their work(14).The actual incidence of radiation - induced cancer depends on many factors, especially age, because of the long delay between radiation exposure and cancer; this can exceed 30 years. An upper limit to the risk of inducing malignant disease by large doses of radiation, in the region of 100 rad or more (delivered in a short period of time), can now be estimated from a number of epidemiological surveys of human populations followed for prolonged periods of time after known radiation exposure. These indicate total risk rates of fatal cancer induction in the region of 100 to 150 cases per million persons exposed to one rad of whole -body exposure. The additional risk of non -fatal (or curable) cancer is likely to be lower. At the much lower dose levels of a few rad (occupational) or a few millirad (general population) exposure per year, there is no adequate evidence of the risk rate per rad, and those quoted may overestimate the risk per rad at these low doses and dose rates. There is no direct evidence of any risk of causing other diseases at these dose levels. The evidence for the induction of malignancies at low radiation doses has been reviewed many times, e.g., in the 1972 BEIR report(2).This evidence has been recently examined(15);the available data for minimum doses producing a detectable increase in the induction of malignancies in humans are summarized as follows:(1) thyroid cancer in children at estimated

12 mean doses of about 6 rad;(2) malignancies following exposure of the foetus, probably at mean doses of a few rad; and (3) leukaemia in the survivors of Hiroshima and Nagasaki exposed to doses of less than 10 rad. A reasonably dependable estimate for radiation carcinogenesis is that for every case of induction of leukaemia 4 -5 other malignancies will eventually occur.

2.2Genetic effects

The genetic effects of ionizing radiation have been known for nearly half a century in a large number of organisms, from microorganisms to plants and higher animals. Regardless of species, the genetic effects of radiation, as of chemical agents, involve attack on DNA, the essential component of the genes. It is well recognized that the incidence of diseases with a partial or full genetic component is significant in human populations (16,1 7). It appears that some 6% of all liveborn children have diseases of genetic origin, divided as follows: (1) 1% dominant and X- linked diseases; (2) 1% chromosomal and recessive diseases; and (3) 4% congenitalanomalies and constitutional and degenerative diseases. More recent data (18) present substantially lower figures for dominant diseases and higher values for the third category (congenital anomalies and other multifactorial diseases). An increase in the mutation rate in humans from any source would be a matter of concern. It is assumed that the dominant or X- chromosome- linked disease would increase in proportion to the mutation rate, i.e., it is assumed that there is a linear relationship between the radiation dose and the frequency of radiation induced genetic diseases. The increase in the mutation rates for recessive diseases is very small, requiring scores of generations to reach an equilibrium value (Table 1). The best estimated value for the doubling dose for protracted radiation exposure is now considered to be 100 rad for both sexes (7). Estimates of the effect of 1 rad per generation on a population of 1 million, assuming a doubling dose of 100 rad, are given in Table 2. Estimates of genetic damage to man from any type of mutagenic agent involves assumptions about dose -effect relationships in low dose and low dose -rate regions. Although precise calculations of genetic damage from radiation, among other mutagenic agents, may not be attainable, it is necessary and possible to make simplified estimates of the probable level of genetic effect (2, 7). Dose -rate data for specific locus mutation induction in mice give a reasonably close approach (at less than 0.8 rad min-1) to a linear dose - effect curve. Some acute exposures have a higher effectiveness, some a lower. The mechanisms causing variation in effectiveness are not known. As a basis for risk estimates, however, the linear regression based on the low- dose -rate data can be used, with suitable adjustment for acute exposures.

13 a Table 1.Effect of a doubling in mutation rate from 106to 2 X 10.6

Number of affected individuals (per 106) Type of detrimental gene Old After one New equilibrium generation equilibrium

Recessive; fitness of as =0 1 aa 1.002 aa 2 aa

Semi dominant; fitness of Aa =0.9 of as =0 20 Aa 22 Aa 40 Aa

Dominant; fitness of Aa =0 2 Aa 4 Aa 4 Aa

Sex linked; recessive fitness of aa and aY =0 3 aY males 4 aY males 6 aY males a After Ramel (19).

As the average"child expectancy" (of having children subsequently) falls rapidly after the age of 30 in both sexes, gonadal radiation exposure is not of the same "genetic significance" at all ages. When the total risk of significant inherited abnormalities is estimated, therefore, the age distribution of the irradiated population must be taken into account. Per rad of exposure, the risk of inducing any serious inherited abnor- mality is estimated as being in the region of 10 -4 (in the first two generations) or 2X 10-4 to 3 X10-4 (in all generations) of the fraction of the radiation exposure which is of genetic significance. For the general population, this fraction is in the region of 0.5 of the total exposure; for occupational exposures it is about 0.25. 2.3 Other carcinogenic and mutagenic agents Many factors, other thanradiation, including exposure to a growing number of chemicals, are now recognized to be carcinogenic and mutagenic (19). Inthe opinion of the International Agency for Research on Cancer (IARC), approximately 80% of all cancer cases have an environmental cause, whereas even higher figures are quoted by others (20). Most of the relevant environmental factors are likely to be man -made or naturally occurring chemicals. Although the world's exposure to potentially carcinogenic and mutagenic chemicals is growing, a quantitative comparison of the relative effects of

14 Table 2.Estimated effects of 1 rad per generation of low dose, low dose -rate, low -level irradiation on a population of one million live births if the doubling is 100 rada

Effects of 1 rad Disease Current per generation : Equilibrium classificationb incidence first generation incidence incidence d

Autosomal dominant and X- linked 1000 - 10 000e 2 - 20f 10 - 100f

Recessive diseases 1 100 Relatively slightVery slow increase

Chromosomal diseases 6 000g ? ?

Congenital anomalies Anomalies expressed later Constitutional and 90 100b 5 - 45' 45 - 450' degenerative diseases

Total 98200 - 107 200 10 - 701 60 - 600g

% of current incidence 0.01 - 0.07 0.06 - 0.6

aAfter San karanarayanan (7). bFollows that given in BEIR report (2). c Current incidence values based on Trimble & Doughty (181 with certain modi- fications. d The first generation incidenceis assumed to be about 0.2 of the equilibrium incidence for autosomal dominant and X- linked diseases; for those included under the heading "congenital anomalies, etc." it is 0.1 of the equilibrium incidence. eThe low value of 1 000 is based on Trimble & Doughty (18) and the high values of 10 000 on Stevenson's used in the 1972 UNSCEAR (51 and BEIR reports (2). f The low and high valuesare based on current incidences of 1 000 and 10 000 respectively. g Based on pooled values from 7 surveys of new -borns; includes mosaics. hIncludes an unknown proportion of numerical (other than Down's syndrome) and structural chromosomal anomalies. ' The range reflects the assumption of 5 and 50% mutational components. Rounded off values.

15 chemical agents and radiation is not yet possible because of a lack of information on the former. The information presented later in this report suggests that, with continuation or improvement of present radiation protection practices, itis unlikely that radiation from present and projected nuclear power programmes will contribute a major fraction of the total carcinogenic and genetic effects observed.

3. THE NUCLEAR FUEL CYCLE

The term "nuclear fuel cycle" refers to the sequence of processes through which the materials used in the production of nuclear energy pass. It covers all steps from the mining of uranium ore to the conditioning, storage and final disposal of the waste materials; the intermediate stages are uranium extraction and milling, enrichment of the fissile uranium content, conversion to fuel, fabrication of the fuel elements, irradiation in the reactor, separation of the unused fuel from the products of the nuclear reaction and its reconsti- tution into fuel. These stages, in each of which potential exposure of workers and public to radiation must be controlled, are illustrated in Fig. 1 and 2 and described briefly in the following paragraphs (see also reference 21). As in the remainder of the report, attention is focused on the nuclear fuel cycle for thermal reactors.

3.1 Mining, extraction and milling

Uranium occurs relatively widely in nature, although it forms only about 2X 104% of the earth's crust. The largest resources are in North America, southem Africa, Australia and Sweden. Present commercial ores typically contain between 0.1 and 0.3% of uranium and are converted into a concentrate known as "yellow cake ". The well- documented hazards of uranium mining, which are dealt with in Section 8, must not be overlooked in any assessment of the health consequences of the nuclear fuel cycle.

3.2 Enrichment

Many reactors have been designed to operate with uranium fuel with its fissile uranium -235 content artificially enriched. Enrichment is now carried out by a diffusion process after conversion of the uranium into a volatile compound (the hexafluoride). Alternative processes being developed commer- cially include use of the gas centrifuge.

16 Fig. 1. The main stages of the uranium nuclear fuel cycle

Mining, extraction and milling of uranium

Enrichment Conversion to fuel

Fabrication of fuel elements

1 Power reactor Waste products operation storage /disposal

Irradiated fuel

Storage Plutonium

Fuel rep ocessing

Uranium

17 00 Fig. 2. The fuel cycle of a 1 000 MW(e) uranium -fuelled water -reactorpower planta Gaseous Gaseous Gaseous 56.7 Ci Rn222 9.43 MT NOx 12.21 MT NOx 0.0226 Ci Ra226 0.11 MT fluorides 0.69 MT fluorides 0.0226 Ci Th230 25.7 MT SO2 22.4 MT SOx 0.0334 Ci U 0.0132 Ci U 0.002 Ci U 15.0 MT NOx

Input 16 acres Isotope Enriched Milling 85,700 MT ore Separation Uranium Mining 2.54x106 MT overburden and Conversion (as UF6 ) (Open - Pit) Concentration U308 -UF6 ( separative 0.2% ore U (as U30e) U (as UF6) work-172 MT)34.53 MT U 2.7 acres 171.4 MT 2.4 acres 171.4 MT 3.3% U235 0.71% U235 1.2 acres Recycled uranium

(T (as UF6) Elec. Energy ) 33.04 MT 1 (j 4.20x108 kwh 0.798% U235 2.54 x 106 Liquid Liquid MT overburden 1.9 Ci U 0.027 Ci U r 0.051 Ci Ra226 0.025 Ci Th' Depleted uranium 3.20 Ci Th230 0.25 Ci Ra226 stored os UF6 170 MT 0.2% U236 Solid tailings 56.3 Ci 86,200 MT 53.5 Ci Th2 0 Liquid: 56.6 CiRa226 0.029CiU Solid: 37.7 MT ash 24.4 MT NaCI Stored solid: 7.91 MT Ca+ 0.26 Ci Th -U 7.91 MT SOq in 15.5 Kg ash 0.52 MT Fe 3.96 MT NO3 Note. The quantities were calculated assuming operation for one year at 100% load factor. The material quantities assume an equilibrium annual reload cycle with each fuel element operating 1100 full -power days prior to discharge, corresponding to an average thermal energy generation of 33 000 MW(e)d per ton of uranium and an average thermal power of 30 MW(e) per ton of uranium. The reactor is refuelled by a programme of partial batch uranium, in which one third of the reactor is replaced with fuel each year. The fresh fuel contains uranium enriched to 3.3% uranium -235. Fig. 2 (continued) Transmission Delivered Electrical Energy: 7.984x109 kwh Electrical Energy: 8.76x109 kwh Transmission Losses: 0.7761109 kwh

Boiling Pressurized Gaseous Water Water 5.18 MT NO3 Gaseous ReactorReactor 8.29 MT NH3 H3 10 to 50 Ci 0.39 MT fluorides 1131 0.3 to 0.8 Ci 0.00019 Ci U Kr + Xe 50,000 7000 Ci

Nuclear Enriched Steam- Electric Uranium Fabricated GeneratingPlant Irradiated Storage of (as UF6) Conversion Fuel Fuel Irradiated Shipment of and 1000 Mwe Fuel Irradiated 34.53 MT U Fabrication 34.53 MT U 33.044 MT U 33.044 MT U Fuel 3.3% U235 3.3% U 32% Thermal Efficiency0.296 MT Pu 0.296 MT Pu P ant area: 160 ocres 150 days 5.17x109 Ci 1.35x108 Ci 2738x101° kwh /yr

Liquid radioactive discharge Circulating water 966,000 gal. /min.

Blowdown water: 7210 gal. /min. 7180 MT dissolved solids Liquid 0.0196 Ci U Cooling Tower BWR PWR 0.0098 Ci Th23 H3 90 450 Ci Other 5 5 Ci

33.8 MT solid CaF2 Humidified air: 23.0x106 MT H2O evaporated 0.059 Ci U in CaF2 1.86 x 1010 kwh waste heat 0.024 Ci other U Drift: 483 gal. /min. Makeup water 481 MT dissolved solids .0 19,230 gal. /min. Fig. 2 (continued)

Surface Water Gaseous. 3340 Ci H3 Ci Kr85 3.67 Ci Ru106 20,580 Ci H3 5.03 MT Na' 0.06 Ci 1129, 131 0.23 MT CI- 0.918 Ci other F.P. 0.415 MT SOâ 0.0037 Ci transuranics 0.176 MT NO3 7.4 MT NOx

Shipped Irradiated High -level Interim High -level Shipment High -level Perpetual Reprocessing ( 5 -year ) Fuel Wastes Wastes to Wastes Storage of Storage of High- Level High Level Federal 3.7 acres 1.32x108 Ci F.P. 1.83x107Ci F.P. Repository 1.83 x107 F.P. Wastes and 0.0015 MT Pu Wastes 114 cu. ft. 114 cu. ft. Other Wastes 20,500 Ci Pu Cladding hulls: Cladding hulls: 11,400 gal. if liqu d 1.67x105 Ci 1.67x103Ci 114 cu.ft. if solid 72 cu.ft. 72 cu.ft. Process water Cladding hulls: 9 gal. /min. 4.28 x106 Ci Storage Area: 72 cu.ft. 0.2 to 1.6 acres

Intermediate -level ( 104 to 106 x MPC 1 liquid wastes to storage: 6900 gal.

> Low -level ( 10 to 104 x MPC ) liquid wastes: 340,000 gal.

Buried solid wastes: 6900 cu.ft.:0.14 acres Sole, recycle or storage Pu (as Pu( NO3 )4 ) 0.296 MT 4.09x106 Ci

Yt 33.04 MT U, 0.798% U

Uranium from the ore concentrate, or uranium hexafluoride after enrichment, is converted by a series of chemical reactions into oxide or metal. In one or another of these forms it is loaded into metal tubes (cladding), which are filled with gas and sealed. The filled tubes, either singly or in clusters, are assembled into fuel elements for insertion into the nuclear reactor. 3.4 Power reactor operation In the core of a nuclear reactor the process of fission (splitting) of the atoms of fuel by neutrons produces heat and a range of lighter elements (the fission products), most of which are radioactive. In an additional reaction, atoms heavier than uranium are produced (the transuranic elements, including plutonium, americium and curium), which are also radioactive and are of special importance in the nuclear industry. The amounts of transuranic elements formed are summarized in Table 3. In normal operation the products of the nuclear reaction are retained within the cladding of the fuel elements. Spent fuel elements unloaded from reactors are stored in heavily shielded areas; they require cooling for some time until the radioactivity of the irradiated fuel has fallen substantially by natural radioactive decay. 3.5 Fuel reprocessing If the waste products and the plutonium are to be separated from the unburnt fuel, the spent fuel containing these materials is transferred after several months to a reprocessing plant in massive, thick -walled containers. There the fuel is dissolved in acid and the solution is treated chemically to separate itinto a number of streams. One stream contains the unused uranium, which is recovered to make new fuel. The second stream contains the bulk of the plutonium, which can be kept for future use in fast reactors or for recycling in thermal reactors. The third stream contains the fission products and most of the other transuranic elements; this is highly radioactive waste. The chemical separation process is carried out remotely in plants equipped for safe handling of the highly radioactive materials. 3.6 Waste management As inall industrial processes, including most methods of producing power, a variety of waste materials is produced at various stages of the fuel cycle. National and international bodies concerned with health and safety have made recommendations and established procedures for managing this waste (23) without undue risk to the general population or the workers in the nuclear industry. The different kinds of waste produced and their present and future management are discussed in greater detail in Section 5 of this report.

21 Table 3. Annual amounts of transuranic elements in the fuel cycle of 1 000 MW(e) nuclear reactors (80%load factor)a

Uranium -fuelled Uranium -plutonium Fast breeder water reactor fuelled water reactor reactor Occurrence Element

kg /a Cita kg /a Cita kg /a Cita

In fuel processing Plutonium 2456 1.06X 105(a) 1 573c 6.78 X105 (a) 1 970d4.49 X 105(a) 3.1 X106(0) 3.1 X107(13) 1.3 X107(0)

Americium 4.39 6.36X 103 (a) 75.7 1.126X 105 (a) 17.8 3.82 X104(a) 1.10X 102 (ß) 2.65 X103(ß) 1.869X 103 (ß)

Curium 0.926 3.80X 105 (a) 9.73 3.65 X106 (a) 0.676 1.12 X106 (a)

Net production in reactor Fissile plutonium 172 - ( -304)e - 132 -

In fuel fabrication Plutonium 0 - 1 958 - 1 757 - a After Pigford(22). 6 1.8% Pu-238, 59.3% Pu-239, 24% Pu-240, 11.1% Pu-241, 3.8% Pu-242.

1.9% Pu-238, 34.2% Pu-239, 31.4% Pu-240, 18.5% Pu-241, 13.9% Pu-242.

d0.77% Pu-238, 66.9% Pu-239, 22.4% Pu-240, 6.1% Pu-241, 3.8% Pu-242.

eRequired make -up from uranium -fuelled water reactors. 3.7 Transport

Continued geographical separation of facilities for different stages of the fuel cycle will require an increasing number of transport operations involving nuclear materials. Transport of raw fuel materials and fresh fuel assemblies do not entail significant radiation risks, whereas transport of irradiated fuel and separated products of the nuclear reaction have a higher potential for accidents which could involve exposure of workers or members of the general population (see Section 7). Co- location of power plants with fuel fabrication and reprocessing plants would reduce but not eliminate transport operations.

4. HEALTH AND SAFETY REGULATIONS OF THE NUCLEAR FUEL CYCLE

In all countries using or planning to use nuclear power, there are extensive regulations, rules, and codes of practice for protection of workers and the public. International bodies, e.g., the International Commission for Radiological Protection (ICRP), provide recommendations on health protection standards (e.g.,24),which serve as bases for national regulations adapted to national and local conditions. These recommendations (examples of which are shown in Tables 4 and 5) derive from extensive world -wide research and experience on the effects of radiation on man, on metabolic behaviour and on studies of dispersion and /or concentration of radioactive substances in air, water and food chains. The scientific bases for these and other radiation -related recommendations are kept under constant review by international bodies such as the United Nations Committee on the Effects of Ionizing Radiations (UNSCEAR), ICRP and IAEA. Continued international cooperation on radiation protection is important, as the distribution of some materials released from nuclear facilities adds to levels of radioactivity on a world -wide basis. Other international actions relating to the protection of the public include the Treaty on the Non- Proliferation of Nuclear Weapons, covering the peaceful uses of fissile materials, and the London and Oslo Conventions on the disposal of low -level radioactive waste at sea. Other relevant material is provided in IAEA publications (e.g., in references25, 26, 27, 28, 29, 30). In most countries the formulation and enforcement of detailed regulations and carrying out national reviews of radiation exposure are the respon- sibility of national radiation protection institutions or special nuclear regulatory or inspection bodies. A basic principle in formulating radiation protection regulations is the ICRP recommendation that all radiation exposures be kept as low as readily

23 Table 4. Maximum permissible annual radiation doses recommended by ICRP for occupational exposure'

Organ irradiated Dose (rem)

Whole -body ) Bone marrow ) 5 Gonads

Skin and bone 1 30 Thyroid gland

Hands and forearms ) Feet and ankles )

Other single organs 15

Note. Values for individual members of the population (except for the thyroid gland of children up to 16 years of age when the limit is 1.5 rem /a) are 10 times lower and for exposed populations 30 times lower than those for occupational exposure.

aAfter International Commission on Radiological Protection (31). achievable, economic and social considerations being taken into account (32). In the nuclearindustry all stages of the nuclear fuel cycle must be considered. For members of the general population, direct measurement of radiation exposure is not practicable, and protection must depend oneffective control of radioactivity releases at the source. Following discharges of radioactive materials with half -lives of days or longer, these materials may travel large distances in air or water. Regulations and dose assessments must therefore con- sider the collective dose to national, regional and global populations. In many cases, regulations are also framed to provide for future expanded use of nuclear power. Regulations covering general industrial activities (site permits, building permits, water discharge permits, boiler codes, etc.) also apply to nuclear facilities, where applicable. Permits for the erection and operation of nuclear facilities are only granted by governmental bodies. Governments therefore exert a more direct control over nuclear power production than over many other industrial developments. Siting of nuclear facilities is subject to special regulations and practices. These may, for example, relate to thermal effects of cooling water, seismic activity and local population characteristics, as well as provisions to include public participation in the siting decision process.

24 Table 5, Some environmentally important nuclides associated with the nuclear fuel cycle, their half -lives and ICRP recommended concentration limits

Derived concentration limits for workers exposed for 40 hours per week' Radioactive Nuclide 3 half -life µCi cmin air pCi cm3in water Soluble materialbInsoluble material

H -3 12.5a 8X10-6 3X10-3 1X10-1 (as water vapour) (as gas) c -2 C -14 5.7X103 a 4X10-6 1X10-7 2X 10 Ar -41 1.8h - 2X10-6 C _c Kr -85 10.8a - 1X10-5 Sr -90 27.7a 1X10-9 5X 10 -9 1X10-5 -8 Zr -95 65.5d 1X10-7 3X 10 2X10-3 Nb -95 35.0d 5X10-' 1X10-7 3X 10 -3 Ru-106 368d 8X10-8 6X10-9 4X10-4 1 -129 1.7X 10' a 2X10-9 7X10-8 1X10-5 I -131 8.1d 9X10-9 3X10-7 6X10-5 Xe -133 5.3d - 1X10-5 - Cs -137 30.0a 6X10-8 1X10-8 4X 10 -4

Np-237 2.1 X 106 a 4X10-12 1X10-1° 9X 10 -5 Pu -239 2.4X 104a 2X10-12 4X10-11 1X10-4 Am -241 458a 6X10-12 1X10-'9 1 X 10 -4 Cm -242 163d 1X10-19 2X 10 -10 7X10-4

a The derived concentration limit,if maintained, will not lead to the relevant maximum permissible annual dose being exceeded. For members of the general population the limits are reduced by a factor of 10 for all radionuclides other than iodine, for which the factor is 20. All limits are reduced by a further factor of 3 if exposure is for the full 168 h w .

b i.e., compounds of the nuclide soluble in body fluids. Limit is based on external radiation from surrounding airborne gas.

25 The Working Group agreed that, in addition to the usual self- monitoring procedures of the nuclear industry, the practice of independent inspection by governmental organizations should be continued and possibly expanded. The importance of broad, high -level training of nuclear facility personnel was emphasized by the Working Group. As in several other industries, mental stability as well as technical capability are essential criteria in the selection of personnel (33). The Group also noted the importance of effective training of the staff of governmental regulatory and inspection agencies.

5. RADIOACTIVE WASTE MANAGEMENT

In general, there are only two acceptable ways of dealing with waste of any kind if it cannot be destroyed or is uneconomical to recycle. It may either be stored in a safe and well- managed way, or it may be disposed of. In the latter case, physical barriers and natural processes, e.g., dilution effects or chemical changes, may assist in reducing the environmental impact to an acceptable level. Both storage and disposal are practised in the case of radioactive waste. It is necessary to maintain a clear distinction between the terms "storage" and "disposal ". Storage signifies the supervised retention of material, isolated from human and other forms of life, but under such conditions that it can be recovered when desirable. Disposal refers, on the one hand, to the discarding of material (in a controlled manner in the case of radioactive waste) with no intention of its ever being recovered; this may be achieved either by deliberate dispersion in the atmosphere, the sea or fresh water, or by isolation from the biosphere. On the other hand, radioactive decay during storage may so reduce the toxicity of the material that immobilizing it at the site of storage may then be considered an adequate form of disposal. It is also acceptable in certain cases to ensure the isolation of the waste for long periods followed by slow dispersion when the initial high levels of radioactivity have decayed away. Storage always involves surveillance of the waste; disposal may involve more limited surveillance of the disposal site. If the irradiated fuel is to be reprocessed, its unwanted constituents and the associated metal cladding and other components of the fuel elements will eventually become waste. If, however, there is no intention to reprocess the fuel, the whole or large parts of the irradiated fuel element itself is treated as a waste material, which must be safely managed. Classification of radioactive waste depends on a number of factors, including the type of radiation, its activity per unit of weight (specific activity), and the toxicity of the radionuclides concerned, including their half - lives. For examples of definitions see the IAEA Report (34). For convenience

26 in this report the terms "high ", "medium" and "low" have been loosely used to quantify the activity of the waste, although these terms do not refer to precisely defined levels of radioactivity. The quantities of waste produced are influenced by the type of reactor, its construction, operating conditions, the site conditions, and by the subsequent treatment of the fuel (for example see Tables 6 and 7). Many publications giving details of waste management procedures, which depend on the nature of the materials and the levels of radioactivity involved, are listed in the references (e.g., 35, 36, 37, 38). 5.1 Highly active waste from fuel reprocessing Nearly all the highly active liquid waste arises from the reprocessing of nuclear fuels. The liquid concentrates from the reprocessing plant after the uranium and plutonium have been recovered contain about 99.9% of the residual total fission product activity. This liquid, which is waste material of very high specific activity, also contains small amounts of unrecovered uranium and plutonium and other radioactive transuranic elements (particularly americium and curium) formed during irradiation in the reactor. Be- cause of the high toxicity of some of the long -lived radioactive components, the waste has to be isolated from the biosphere for a very long time. At the time of separation of the waste from the uranium and plutonium, nearly all of its activity is due to the fission products. Although at first the activity of the fission products falls quite rapidly as the shorter -lived radionuclides such as strontium -90 and caesium -137 (which have half -lives of about 30 years), require isolation for a few hundred years. By this time, the toxicity of the waste would have decayed by a factor of over a million. Several of the highly radiotoxic isotopes of the transuranic elements contained in the waste have half -lives of thousands of years, and after a few hundred years they become the dominant hazard (see, e.g., Fig. 3). Although the fission product activity of the highly active liquid waste (about 109 Ci per 1000 MW(e)a of power produced after one month's storage) is largely independent of reactor type, the degree of concentration achievable and hence the final volume of the liquid waste depends on the chemical separation process used. However, the volume is always very small per unit of power produced, compared with that of (less toxic) waste from fossil fuel power production. As an example, the total volume of highly active liquid waste produced from the United Kingdom nuclear power programme since its start in 1955 is less than 700 m3 (40). By the end of the century this could reach at most 6000 m3 containing 1010 Ci of fission products and 108 Ci of transuranic elements. At present, this waste is stored in specially designed, cooled, steel tanks with outer containment. In the more modern, doubly contained, stainless steel tanks, monitoring would rapidly detectany leak, and spare tank capacity is always maintained. Experience with modern designs of tank has led to confidence that this method of storage could be safely continued for many decades.

27 Table 6. Annual production of liquid waste from operation of a 1 000 MW(e) pressurized water reactor (PWR)a

Annual volume (m3) Annual volume (m3) Characterization of the waste of untreated waste of conditioned waste

Activity Radioactive Reactor Fuel Reactor Fuel Category or (Ci m ) contaminantb operation reprocessing operation reprocessing

s Very low 10to10-2 FP + AP 7 000 - 4 to 8 -

Low <1 FP + TU 4 000 2 000 20 20

Medium <1 000 FP + TU - 45 - 45

High >1 000 FP + TU - 40 - 4

aPersonnel communication from Dr P. Dejonghe.

b FP= mixed fission products AP = activation products TU = transuranic elements

The figures given for reprocessing were obtained by estimation of the volumes anticipated for an industrial -size reprocessing plant capable of handling 500 -1 000 t/a of uranium, corresponding to the needs of 15 to 30 PWRs of 1 000 MW(ela. They depend considerably on the chemical separation and waste conditioning processes. Table 7. Summary of rates of discharge of radioactive materials to atmosphere for various reactor types'

Discharge rate Ci per 1000 MW(e)a

Krypton -85 Iodine -129 Tritium Carbon -14 Reactor

At reprocessing At reprocessing At At reprocessing At At reprocessing plant plant reactor plant reactor plant

PWR 3X 105 10-2 12 5X103 6 1.5

BWR 3X105 10-2 20 -100 5X 103 15 1.5

Magnox 3X105 10-2 - 5X103 6 6

HWR 3X105 10-2 -2 104 5X103 10 1.5

aAfter Commission of the European Communities (39).

N Fig. 3.Relative ingestion radiotoxicity of components of highly active waste and naturally occurring radioactive pitchblende.a

106

Fissionproducts in1g of wasteglass

104

103 .. Transuranicelements

Typicalfor \.., 1gpitchblende \ 10 '

1 10 102 102 104 105 Age of wastes (years)

Assumptions:pressurized water reactor fuel, uranium fuel cycle, 1% plutonium in waste, 15% waste in solidified (glass) material, typical pitchblende toxicity normalized to unit weight.

aAfter McGrath (41), additional data for pitchblende provided by Dr B. Skytte- Jensen (personal communication, 1977).

30 Any storage system needs surveillance, but the degree and importance of surveillance would be reduced, and the storage of the waste made even safer, if the liquid were converted to a stable solid. In a number of countries relevant development programmes are well advanced, the favoured product being a form of glass which has been shown to be highly resistant to water leaching, to chemical attack and to high levels of radioactivity. Plans are being made to store these blocks of glass, encased in steel, in a cooled, controlled and moni- tored environment. 1000 MW(e)a of nuclear electricity would result in from 1 to 4 m3 of contained vitrified high -level waste, depending upon its decay time and chemical composition. It has been reported(43,44) that a nuclear power programme rising to 100 000 MW(e) installed by the end of the century would produce, by then, about 3000 m3 of vitrified waste which could be stored in water basins covering an area of ground less than 10 000 m2. The Working Group considered it important that the development and testing of solidification processes continue energetically. There is no technical reason why such methods of engineered and supervised storage should not be safely applied indefinitely. Even so, various methods are being developed in several countries for this waste to be disposed of in isolation from man's environment without the need for permanent supervision. These studies include examination of burial in deep geological formations, such as salt domes, clay or hard rock, and disposal in or on the deep ocean bed (42).In Europe the Commission of European Communities (CEC) is coordi- nating a comprehensive programme of work in this field (45). An illustration of the radiotoxicity of vitrified highly active waste can be gained from comparing it with the toxicity of naturally radioactive minerals. Such a comparison is shown in Fig. 3, indicating the relative radiotoxicity of fission products and transuranic elements in the glass and naturally occurring pitchblende. All toxicities are evaluated on the basis of data from ICRP and are derived from ICRP recommendations on maximum permissible nuclide concentrations in drinking- water. It is to note that after some 1000- 3000 years the toxicity of the waste material will become (gram for gram) less than that of typical radioactive minerals. Geological stability at the disposal site is important and it is relevant to note a recent discovery that 2000 million years ago high uranium concentrations, in the Oklo mine in Gabon, West Africa, initiated a number of natural "reactors" which operated for about a million years (46). Evidence on the migration away from their site of formation of the tons of fission products and transuranic elements formed by these natural reactors con- firms what would have been expected from geochemical knowledge. Those elements which, from their chemical and physical properties, would have been expected to remain had done so, and those which would be expected to be mobile, had moved. There is evidence that plutonium -239 did not mig- rate during its lifetime, and the circumstances were certainly less favourable than would be expected in a carefully selected disposal site.

31 A number of more exotic suggestions for disposal have been made, such as firing the waste into space in rockets and burial in the polar ice caps (47). In principle, it is possible to convert the very long -lived component of the waste into shorter -lived or stable materials. If the small amounts of transuranic elements associated with the fission product waste could be separated and used as fuel in a reactor, they would eventually be converted into shorter - lived or stable fission products (nuclear incineration) (48). After a total of 30 years of neutron irradiation, 99.9% of the transuranic elements would be converted to fission products. This approach is theoretically feasible, but development of the specialized new technology would be lengthy and expen- sive. The processes involved are being examined collaboratively in a number of countries, but there is no assurance that its application would give an overall environmental advantage compared with disposal without separation: the introduction of new plants and new processes would inevitably result in an increasein occupational exposure. Although nuclear incineration would substantially remove the long -lived radioactive component of the waste, itis not a disposal method and should not be looked upon as an alternative to the disposal options already referred to. The Working Group concluded that there are a number of options for the safe disposal of high level radioactive waste and that no insurmountable technical problems have been identified. However, to reach a conclusion as to the best option will involve substantial research programmes. Such programmes and the present trend towards international collaboration should be encouraged. Although for the proper development of nuclear power it will be necessary to demonstrate the feasibility and safety of any disposal route, the Group concluded that the lack of any immediate need for deciding and acting upon a method allows time for proper and thorough evaluation of the options. Pressures to take rapid and irreversible decisions that might eventually prove to be premature and ill- advised should be resisted. In summary, experience has shown modern methods of storing liquid waste to be safe; technology and plans for converting this waste into solid form are well advanced, and a number of technologically and economically feasible options for final disposal are under detailed study.

5.2 Other highly active solid waste

Much of the highly active solid waste arising from the nuclear industry consists of contaminated swarf or metal cladding removed from the irradiated fuel before reprocessing and highly activated structural parts of reactor cores. At present, these and other highly active wastes are stored in heavily shielded facilities. Retrievability of the waste for final disposal must be a consideration in the design of these facilities. The major source of the long -lived activity is small amounts of irradiated fuel which adhere to the metal. Waste from the reprocessing of high burn -up fuel, e.g., from fast reactors, will present a

32 special problem because of the presence of plutonium and other transuranic elements. Decontamination to reduce the amount of plutonium will be necessary in the preparation of the waste for long -term storage or disposal.

5.3 Medium and low activity solid waste

All major users of radioactive materials produce a miscellaneous collec- tion of solid waste of medium and low activity. At power stations, active sludge and ion exchange resins arise from the treatment of liquid effluent and cooling pond water. At present, according to its level of radioactivity, some of the waste in this category is stored in a retrievable way, some is buried in controlled areas, and some is immobilized in concrete or bitumen and disposed of into the deep ocean(49, 50, 51, 52). Several dumping operations into the north Atlantic Ocean have been jointly carried out since 1967 by a number of European countries under the surveillance of NEA /OECD. It is strictly controlled in respect of amounts, packaging, the dumping area, safety precautions during transportation, etc., and the operations are carried out within the terms of the 1972 London Convention (the Intergovernmental Conference on the Dumping of Wastes at Sea), which requires prior authorization from national authorities and pro- hibits the dumping of high level waste. Following this Convention, IAEA was asked to define the upper limits for dumping. The present IAEA definition (53),which is subject to periodic review, defines the waste according to the type of radiation and its concentration on an activity /weight basis; it assumes an upper limit of 100 000 t a-1 at any one site. Although aware of some public concern on possible late consequences of dumping waste into the oceans, the Working Group recognized that current levels of dumping represent only a minute fraction of the amounts permitted in the IAEA definition and are a factor of 10' lower than the amounts which the model adopted by NEA /OECD (54) predicts could give rise to exposure at the ICRP recommended maximum permissible level. The Group recommended that studies be continued in this and alternative fields of waste disposal and called on WHO and IAEA to accelerate acceptance by the member states of the IAEA recommendations on procedures, as requested in the Final Act of the London Convention (55).

5.4 Medium and low activity liquid waste

A variety of medium and low level liquid waste arises from nuclear power stations and reprocessing plants and from medical, laboratory and industrial uses of radioactive materials. In the nuclear industry this waste is treated, if necessary, to reduce its content of radioactive materials to a level at which the effluent is safely discharged to the environment. Such treatment also produces various forms of solid waste which have to be stored. The

33 amounts of low activity liquids which are permitted to be discharged to the environment are determined by national regulatory bodies on the basis of international recommendations in such a way that exposures to the general public are kept well below accepted health protection standards. For example, the impact on man and on the aquatic environment receiving liquid effluent depends on the quantities and nature of the materials discharged and on the conditions of the release, particularly on the radionuclides concerned and the degree of initial and final dilution in the water mass. The Working Group stressed that particular attention must be paid to the possible effects on man through various exposure routes, e.g., food chains, rather than to the possible (and probably temporary) effects on aquatic populations. Before major discharges are made, it is important to establish the predominant exposure routes for man through bioaccumulation and /or external radiation. During and following periods of discharge it is necessary to carry out appropriate monitoring programmes and to publish the results in terms of human exposure. The Group agreed that current and predicted releases of radioactive waste to the sea make only a minute addition to its total natural levels of radioactivity (25C Ci km-3, mainly potassium -40) and that extensive data offer no evidence that these releases have been harmful to man (56). However, prudence dictates that the exposure routes leading to man and to accumulation in marine organisms should be kept under close review. As the nuclear industry grows, maintenance of the present low levels of exposure (see Section 8) will demand improved decontamination of some of the liquid effluents. The Working Group recognized that developments are being undertaken to achieve these improvements. Discharges to the aquatic environment have been the subject of extensive review, and there are many detailed publications (50, 51, 57).

5.5 Discharges into the atmosphere

Discharges from reactors into the air may include argon -41 (from irradiation of air), krypton -85(afission product), xenon -133 and isotopes of iodine, and carbon -14 from irradiation of reactor materials. From fuel reprocessing plants, the most volatile elements still remaining in the fuel, most importantly krypton -85 and tritium, are likely to be released during dissolution of the fuel. Quantities of radionuclides which could be of importance to health are eliminated or reduced to acceptable levels by present technology. Atmospheric transport on a global scale and the long half -lives of some of the radionuclides concerned necessitate an evaluation of the collective exposure of populations on a world -wide as well as on a local or individual basis. To be effective, control measures to limit exposure from discharges of these radionuclides will require international agreement and implementation.

34 The discharges of greatest importance in the nuclear industry consist of long -lived tritium, carbon -14, krypton -85 and iodine -129. Tritium (half -life 12.2a) is produced naturally in the atmosphere by the interaction of cosmic rays with nitrogen and oxygen. Its production rate is 1.6X106 Ci a-1 and the natural inventory is 2.8X107 Ci. Ninety per cent of natural tritium is in the hydrosphere, 10% in the stratosphere and 0.1% in the troposphere (1). Tritium can be formed in reactors in a number of ways, e.g., by neutron activation of constituents of light or heavy water or as a fission product. Total production in gas -cooled and light water reactors has been quoted as about 2X104 Ci per 1000 MW(e)a and from heavy water reactors as about 5X 105 Ci per 1000 MW(e)a (39, 58). Its quantity in, and distribution among, the various waste streams also depend on the reactor type and on the nature of the cladding and quality of the fuel (39). Dilution in the sea is likely to result in a lower radiological impact on the population than discharge to atmosphere. In the long term, schemes will be required to prevent tritium from reaching waste streams and for its safe storage or disposal. Carbon -14 (half -life 5730a) is continuously formed in the upper atmosphere through cosmic ray bombardment at a rate of about 3X 104 Ci a-1, maintaining a total atmospheric inventory of 2.8X 108 Ci. The human body contains about 10 -9Ci. Small quantities are produced in reactors by the reaction of neutrons with atoms of nitrogen, oxygen and carbon in fuel, coolant and moderator. The production rate of carbon -14 will vary with reactor type, graphite moderated gas -cooled reactors producing more than light water or fast reactors for which the production rate has variously been quoted as 10 -50 Ci per 1000 MW(e)a (6, 59). The relative fraction discharged from reactors and reprocessing plants also depends on the reactor type (39). The Working Group noted that technology to reduce carbon -14 discharges is being developed and will be available when required. At fuel reprocessing plants the greatest discharge of radioactivity to the atmosphere is of the noble gas krypton -85 (half -life 10.8a), a fission product which is released into the atmosphere on dissolution of the irradiated fuel. A 1000 MW(e) power reactor will produce about 3X 105 Ci of krypton -85 in a year's operation (39, 58). It has been estimated (60) that at the end of the century the atmospheric inventory could be more than 109 Ci, producing a genetically significant dose approaching 1% of that from natural background radiation. Means for removal and safe storage of krypton are being developed for the time when they are deemed necessary. Although the shorter -livediodine -131fission product (half -life 8d) has substantially decayed beforefuelreprocessing, iodine -129 (half -life 1.7X 107a), formed in much smaller quantities (about 1 Ci a-1in a 1000 MW(e) reactor (39)) has a half -life of 16 million years. Radiological protection authorities do not expect that health considerations will necessitate further provisions for removing it from airborne effluents from reprocessing plants for the time being, but if the need arises methods for doing so already exist.

35 6. SITING AND DECOMMISSIONING OF NUCLEAR FACILITIES

6.1 Siting Factors influencing the selection of sites for nuclear facilities include site characteristics which influence the effects of normal or accidental releases of radioactivity (population distribution, hydrology, meteorology and land use for agriculture or industrial purposes), site technical features (transmission lines, availability of cooling water, accessibility), site characteristics possibly endangering the facility (flooding, earthquakes, geotechnical features of the soil, transport operations) and amenity and economical factors (including possible future use of the land). IAEA has recently issued a publication dealing with many aspects of siting nuclear facilities (27). In the unlikely event of an accidental release into the atmosphere of radioactivity from a nuclear plant, an important factor affecting control of potential population exposure is the population density and distribution near the facility. Criteria have been developed by some licensing authorities which specify an acceptable population distribution relative to the plant design and its engineered safety factors. With improving safety technology, and a growing desire to locate power plants close to energy consumption areas, there has been a tendency in the past few years towards accepting higher population density sites. Population characteristics of nuclear sites vary widely, with densities from less than about 0.1 persons per km2 within 20 km from the site to sites with a population of more than a million persons within 20 -30 km. Exclusion zones with various restrictions around power plants vary from 0 to about 2 km. The Working Group strongly emphasized that remote siting cannot be considered as a substitute for sound design, construction and operation of the plant.

6.2 Decommissioning

The operating life of a commercial nuclear reactor is variously assumed to be 25 -35 years (49). Most of the sites licensed for nuclear power plants were chosen for features which provide a strong incentive for their continued full use. It would therefore normally be desirable for a plant at the end of its life to be dismantled, as far as is necessary and as quickly as is consistent with safety, to make way for a new plant which can use existing site facilities. Some nuclear installations, including a number of small reactors and other plants, have already been successfully dismantled. This experience includes the decommissioning of the 22 MW(e) Elk River reactor and an experimental fast reactor in the USA. A large section of the fuel reprocessing

36 plant at Dounreay in Scotland was decontaminated prior to its reconstruction to handle fuel from the 250 MW(e) fast reactor, and dismantling operations have begun on the Le Bouchet uranium fabrication plant in France. But dismantling has not yet been necessary for large power reactors. After years of operation many reactor components and structures will have become radioactive as a result of their intense irradiation by neutrons, and some will have become contaminated. Their dismantling will require special techniques and will create thousands of tons of waste material of various low and intermediate levels of radioactivity. In the steel structures the activity will at first be dominated by relatively short -lived isotopes of iron and cobalt. Later, however, the longer -lived nickel -63 (half -life 92a) becomes the principal radionuclide, and after 40 -50 years the total activity in the steel will decay with a half -life of about 100 years. There are also smaller amounts of longer -lived radionuclides, such as nickel -59 (half -life 8X1 04 a). For a number of years the problems and costs of decommissioning redundant nuclear plant (particularly reactors) have been under examination. Three stages are envisaged.

Stage 1. Permanently taking the installation out of service, without dismantling it, and putting it into a state in which it would be safe under routine surveillance and monitoring. Stage 2. Reduction of the installation to the minimum size without penetrating the highly irradiated or contaminated parts, e.g., those associated with the reactor core. Surveillance of the plant and the environment would be continued.

Stage 3. Complete removal of radioactive components of the plant and release of the area without restriction.

Decisions on how far to proceed will depend on energy demands, on economic considerations, on the radiation exposure penalty to the dismantling staff, and on future policies on the disposal of radioactive waste. Al- though it is premature to make firm cost estimates, it is likely that the cost of dismantling would be a reasonably small fraction (perhaps a few per cent) of the initial investment. An IAEA Technical Committee (61) has considered various aspects of decommissioning. Whatever the future policies may be, it will be important for the site layout and the design and construction of nuclear plants to incorporate features which would aid their eventual decommissioning and dismantling. Requirements to this effect, on plant design, etc., are being implemented in several countries.

37 7. ACCIDENTS IN THE NUCLEAR FUEL CYCLE

As is the case with all energy production facilities, nuclear plants entail risks of accidents that could affect workers and the public. This section discusses potential accidents in the thermal reactor fuel cycle that could conceivably lead to substantial releases of radioactive materials to the atmosphere and hence to uncontrolled radiation exposures of the population. (The case of the fast reactor was not specifically discussed by the Group.) Occupational accidents in the nuclear industry not involving radiation exposure are also considered. Extensive analyses have been made of the probabilities and health consequences of accidental releases of radioactivity from nuclear facilities. Nuclear plants are designed and constructed so as to ensure very low probabilities for accidents that could potentially have serious consequences for the public. If such an accident did happen, siting policies (Section 6) and emergency plans and procedures would help to mitigate the consequences. 7.1 Power plant accidents A number of detailed studies have been made to assess the probabilities and health and environmental consequences of reactor accidents(62, 63, 64, 65).All these studies are consistent in showing low risks for the population from nuclear power plants (66). Even following simultaneous failure of a number of independent safety systems, a major release of radioactivity can only take place after the fuel has overheated, a substantial part of the reactor core has melted, and the barriers surrounding the fuel and the reactor have been broken. In general, therefore, it is the gaseous and volatile fission products which would be released most readily. Such an accident could conceivably lead to radiation exposure of large numbers of people in the population. Froni a public health point of view, the most important isotopes would be those of the fission product gases (krypton and xenon), iodine (iodine-131), tellurium, ruthenium and caesium (caesium -137). Following a release, a cloud of radioactive material could be carried downwind, progressively decreasing in concentration, at a rate which would depend on wind speed and weather conditions, and with a reduction in radioactivity due to radioactive decay and deposition. At very short distances direct radiation from the cloud would be important, but as the cloud dispersed inhalation of fission products would be the dominant immediate hazard. For the first few days the most important source of exposure would be radioactive iodine, but after some time radiation from deposited caesium would be the dominating factor. The most important factors in determining the consequences of a given release of activity are the meteorological conditions, the population distribution, and the actions taken to mitigate the consequences, such as taking shelter or eventually evacuating.

38 The most detailed study of reactor accidents is that sponsored by the US Nuclear Regulatory Commission (62). Although this study (referred to below as the Reactor Safety Study (RSS)) was made for American conditions (60 actual reactor sites in the USA were considered), the results are in line with studies carried out in other countries. The main results are summarized in Fig. 4. In order to put the nuclear accident risks for society into perspective, data for other types of major accidents caused by the activities of man are included. A tabular presentation of the data pertaining to the acute death risk is given in Table 8, which refers to the USA. The long -term effects of a reactor accident could include genetic effects and cancer. The total numbers of delayed deaths could be substantially greater than the numbers of acute deaths. The RSS concluded that, for exampsle, for the serious accident which might occur at a frequency of once in 10reactor years of operation, the number of delayed cancer deaths per year would be similar to or somewhat greater than the number of acute deaths. For accidents of decreasing severity (and higher probability) the number of cancer effects would be increasingly important relative to the number of acute deaths. However, on a national basis, the number of these health effects would be difficult or impossible to detect statistically from the normal incidence rate. The RSS further shows that whereas there is a small probability of a large accident (for instance, about 1 chance in 100 million years for an accident in one reactor causing 1000 acute radiation fatalities), an accident involving melting of the fuel in the reactor core will most probably not lead to breaches of the containment and hence will not result in any acute radiation- induced fatalities, cancers or genetic effects in the public. The RSS was based on a detailed examination of possible plant failures that could lead to radioactivity releases. There is no way of proving with absolute certainty that all possible failure sequences that could contribute to public health risk have been taken into account. However, the systematic approach used in identifying possible accident sequences makes it very unlikely that a dominant contributor to the overall risk was overlooked. Al- though not extensively reported, parametric studies were performed, as part of the RSS, to test this conclusion. These studies gave corroboratory results. A further important factor is that only those failure sequences that could lead to core meltdown need be considered, substantially limiting the type and number of failures of equipment and human failures that could contribute to public risk (reference 62, Appendix XI, Chapter 3). In discussing the probabilities and consequences of possible major accidents involving nuclear power plants, the Working Group saw no reason to dissent from the general conclusions of safety analyses recently carried out in a number of countries which have assessed the risk to the public from accidents involving releases of radioactivity from the reactor core to the environment as

39 Fig.4. Examples of frequency of accidents involving acute fatalities due to human activities, including operation of nuclear power plants'

y, I

J`,3 o, ------t-

10 -1

10 `--

- -

I 0-5-^ I -t -+ - -

I I I

I I 100 Nuclear Power Plants 10-6 - -1- - - 1-- - -

I I I

I I I I

I I I I 0' f 1 i 1 I 10 100 1 000 10 000 100 000 1 000 000 Number of acute fatalities (X) per accident

aAfter Reactor safety study - an assessment of accident risks in US commercial nuclear power plants (62). Reproduced by kind permission of the US Nuclear Regu- latory Commission.

40 Table 8.Risks of acute death from various causes'

Annual number Accident type Individual death of fatalities risk per year

Motor vehicle 55 791 1 in 4 000

Falls 17 827 1 in 10 000

Fires and hot substances 7 451 1 in 25 000

Drowning 6 181 1 in 30 000

Firearms 2 309 1 in 100 000

Air travel 1 778 1 in 100 000

Falling objects 1 271 1 in 160 000

Electrocution 1 148 1 in 160 000

Lightning 160 1 in 2 000 000

Tornadoes 91 1 in 2 500 000

Hurricanes 93 1 in 2 500 000

All accidents 111 992 1 in 1 600

Nuclear reactor accidents 1 in 5 000 000 000 (100 plants) (estimated)

aAfter US Nuclear Regulatory Commission (62).

41 low. It was pointed out that although, as in any industry, many small and localized accidents might occur, their impact would be more likely to involve loss of generating capacity and financial penalties than physical harm.

7.2 Transport accidents The potential for accidental radiation exposures of the public during transport of radioactive materials in the nuclear fuel cycle is, in practice, mainly associated with the transport of spent fuel elements from power plants to reprocessing plants and possible future transport of high level waste from reprocessing plants to waste storage installations or disposal sites. IAEA has published recommendations for the transport of radioactive materials including spent fuel elements (26). They include requirements that type B transport casks (those used for potentially more hazardous consignments) are able to withstand the following conditions without the escape of radioactivity from the cask: -a free fall of 9 m on to a hard surface; a free fall of 1 m on to a 15 cm diameter steel bar; a 30- minute fire at 800 °C; immersion under water to a depth of 15 m. Thus, it is considered highly unlikely that transport accidents could rupture the cask and the fuel assemblies and thereby give rise to harmful releases of radioactivity. As the fuel assemblies are stored for extended periods before shipment, most of the radioactivity will be due to the longer lived strontium -90 and caesium -137, which are not volatile. Numerous studies have been performed on the risks and consequences of transport accidents (67, 68). Estimates suggest that an accident serious enough to cause a minor release of radioactivity may occur once every 80 -200 million vehicle .km for road and rail. One 1100 MW(e) reactor can be expected to require about 60 truck or 10 rail shipments of spent fuel per year (69). In the USA to date about 4000 shipments of spent fuel have been made. Half a dozen serious accidents have taken place during these shipments. In no case has a type B package released activity into the environment as a result of an accident and in no case have members of the population been exposed to excessive doses of radiation. In an accident causing rupture of the shipping container, any radioactive contamination occurring would be localized. Although in extreme cases evacuation of people from the immediate vicinity might be desirable, more general evacuation, although common in accidents including releases of other toxic materials such as noxious gases, would not be necessary (68). On the basis of experience and the assessment studies made, the Working Group concluded that public health risks from transport of spent fuel are very small.

42 High level radioactive waste will be transported from reprocessing plants to waste storage or disposal sites only in solidified form and a number of years after the fuel has been taken out of the reactor. Considering the form of the waste and the lower number of transport operations, the public health risks from the transport of high level waste are expected to be even less than those from spent fuel transportation. 7.3 Accidents in fuel reprocessing plants A reprocessing plant may contain roughly as much radioactivity as a 1000 MW(e) operating reactor. However, all fission gases except krypton -85, as well as the most volatile fission products, will have substantially decayed. The most important nuclides will be strontium -90, ruthenium -106 and caesium -137. Operations in reprocessing plants do not involve high pressures and temperatures and involve a lower specific heat generation than in a reactor; the potential for releases of radioactivity into the atmosphere or into water is lower, even though the material is mostly present in liquid form during the reprocessing operation. Hence, itis not considered likely that major concentrated releases to the atmosphere could occur that would lead to public health consequences similar to those which might follow a major reactor accident. 7.4 Accidents during disposal of high -level radioactive waste As indicated in Section 5, a likely method of permanent disposal of solidified high -level radioactive waste is in geologically stable formations underground, e.g., in rock salt or other rock formations. The extreme consequences of an accident following disposal would involve total leaching of the radioactivity into ground water, which would subsequently reach surface water and be consumed by the public. An extensive study of the worst possible situation has been made (78), assuming burial in average, undisturbed geological formations. Following leaching, movement of radioactive materials in the ground water towards the surface would be retarded by chemical and physical processes in rock and soil. The delay in reaching the surface would be tens of thousands of years for strontium -90 and probably millions of years for the transuranic elements. If this water were ingested by the population, the study estimates that it could cause less than 0.5 fatality during the first million years after disposal. A combination of this type of accident with major geological upheavals could have more serious consequences. However, disposal sites would be carefully selectedin areas of high geological stability and isolated from moving ground water (or where the flow of any ground water is very slow) (see also Section 5.1). The probability of an accident involving exposure to man following carefully controlled disposal of high -level radioactive waste is considered to be remote and would have very limited consequences.

43 7.5 Procedures for mitigating the consequences of accidents

Following accidents involving the release of radioactivity to the environment, the implementation of comprehensive emergency plans would serve to reduce substantially the public health impact. In some circumstances limited evacuation of people from the downwind sector might be necessary. In case of longer -term hazards due to contamination, consumption of 'food and drink might have to be controlled for a period of time. Other actions might include decontamination and distribution of tablets containing stable iodine to reduce thyroid uptake of radioiodine. Mitigating actions will vary according to the type of accident, local conditions, available facilities, etc. It is expected that local and central health authorities would be heavily involved both in planning and execution of the emergency plan. In taking decisions on emergency action, e.g., evacuation, it must not be overlo'oked that these actions may have associated risks of their own, e.g., transport accidents, and due regard must be paid to the local conditions at the time of the accident. Emergency plans and radiation monitoring programmes must be developed in close cooperation between the relevent public health authorities and the staff at the nuclear facility. Periodic exercises involving plant personnel, emergency teams and local authorities should be carried out. IAEA and WHO have issued reports on the role of public health authorities in the radiological field (49, 71).

7.6 Non -radiationoccupational accidentsinnuclear power production As for other types of energy production, nuclear power brings with it the risk of occupational accidents in fuel production, plant construction and operation, transport and handling of waste. A summary of some recent data (6, 72) is presented in the final column of Table 9, which shows that the non -radiation occupational accident fatality rate in the nuclear industry is dominated by mining and construction accidents.

S. RADIATION EXPOSURES FROM NORMAL OPERATION OF THE NUCLEAR FUEL CYCLE

Drawing on the combined experience of members of the Working Group and on the results of a review made for NEA /OECD (6), the state of knowledge on present health risks from radiation exposure from the various stages of the nuclear power industry was reviewed.

44 Table 9.Collective whole -body doses, partial -body exposures and occupational fatality rates occurring at different stages of the nuclear power production process

Whole -body exposures Occupational (manrem per MW1e)a) Partial -body (non -radiation) Stage exposures fatalities Population Occupational per 1 000 MW1e)a

Construction of installations - - - 0.25

Uranium mining - External, to miners 0.05 Lungs (miners) 0.1

Milling and processing - (Probably) <0.1 Lungs and hands, slight -0.1

Fabrication and enrichment - - Probably slight <0.01

Liquid waste From activation and Reactor operation <0.01 fission products (external - 0.02 Gaseous waste and tritium) 1.0 0.1 Carbon 4 Liquid waste O. a From activation and Occupational, occasionally to 0.2 fission products lungs and other tissues. Reprocessing plants Gaseous waste (mainly external) 1.0 Public, to skin, intestine, thyroid 0.02 0.25 and bone for small groups

Other fuel steps - 0.03 - <0.01

Transport <0.01 <0.01 - <0.01

Accidents 0.05 - - <0.01

Decommissioning - 0.03 - 0.05

TOTAL 0.7 2.2 - 0.55

TOTAL (genetically significant) 0.3 0.6 - -

a Exposure from carbon -14 integrated over 500e and assuming 90% retention (see Section 8.4). Modified after Pochin 16). The doses received by members of the population are generally too low to be measured directly. In most cases they must be estimated by using models of the distribution of radioactive materials following their release into air or water in association with surveys which identify the exposed population and important exposure pathways. This review takes into account exposure of individuals, populations near nuclear sites and, where appropriate, global populations. In drawing conclusions as to health effects from radiation exposure, the Group used the best current information on dose/ effect relationships, as detailed in Section 2: for radiation protection pur- posesa linear relationship extending down to the very lowest levels of radiation to which the general population is exposed from nuclear power operations was adopted following ICRP recommendations (32). The analysis takes account of the total dose involved, including not only the dose received during the year of operation but also that to which the population is com- mitted in the year of operation to receive in the future. The total exposure of populations is expressed as "collective doses" in manrem and represents the average dose or dose commitment in rem multiplied by the number of persons in the population considered (see Annex I). The calculated health effects are summarized in terms of the total collective dose per unit of nuclear electrical power production. The main sources of exposure involve whole -body radiation. The radiation exposures received as a result of the operations of the nuclear industry must be of man from other man -made sources (medical applications, nuclear weapon fallout and con- sumer products) and the inescapable background radiation from natural sources (from cosmic radiation, radioactive constituents of rocks and building materials and from radioactive materials present naturally inall human bodies). The levels of these various sources of radiation are shown in Table 10. Geographical variations in the natural levels of terrestrial radiation, even over small distances, far outweigh increases in radiation exposure calculated from the world's predicted nuclear power programmes.

8.1 Construction of installations

The only significant potential source of radiation exposure during construction of nuclear plants, as for other large constructional projects, is industrial radiography.

8.2 Mining and milling

The mining of uranium ore is associated with radiation health risks due to the inhalation of radon and its daughter products. The principal internal radiation exposure is from alpha radiation, the emitters being attached to very small particles which are inhaled from the mine atmosphere. The problem

46 Table 10. Estimates of average annual whole -body radiation exposure (mrem) to the population from various natural and man -made sources'

United USA Kingdom

Source 1970 2000 1973

(whole -body dose) (gonad dose)

Natural background 102b 876 Cosmic radiation 44 28 Terrestrial radiation 40b 38b Internal radiation 18 21

Medical practices 73 -73 14

Man -made environmental Global fallout 4 5 2.2 Nuclear power (wastes) 0.003 0.4 0.01c Miscellaneous sources 2.6 1.1 0.7

Occupational exposure 0.8 0.9 0.6 (from nuclear power production, industrial radiography medical and dental work, etc.)

Total 182 182 105

aAfter National Academy of Sciences, National Research Council (2) and Webb (72).

bThere are wide variations in natural levels of radiation and individual levels of exposure in different parts of the same country. For example, the United Kingdom study (72) reports individual variations of 65 -200 mrem.

c More recent estimates suggest a figure of about 0.1 mrem.

47 seems to be minimal in open -pit mines and may be partially controlled underground by care through mine ventilation and related measures, such as sealing off unused sections of a mine. The technology needed to provide acceptable working conditions appears to be available. Although personal protective devices may be used their overall effectiveness is probably low due to various physical and usage factors. When radiation levels in the mine atmosphere are not adequately controlled, serious health consequences result. The health consequences and epidemiology have been thoroughly reviewed and evaluated (25, 73,74,75, 76, 77). Health consequences of mining must be considered as an inevitable component of the use of nuclear fuel and should not be overlooked in countries which do not mine uranium but import it. The cumulative radiation exposures of uranium miners are expressed (76) in terms of working levels months (WLM), the cumulative product of periods of underground exposure in working months (each of 170 hours) and the corresponding air concentrations of radon daughters in working levels (WL)a. Much of what we know about the exposure- response relationship between inhalation of radon and its daugher products and lung cancer comes from a study of miners in the USA during the period 1951 -1960 and in Czechoslovakia. In the American study (73), the exposures of the miners were estimated from their histories of employment and from yearly average (measured or estimated) mine radiation levels. Subsequent mortality of the miners, including lung cancer mortality, was then related to the estimated radiation exposures and other important factors such as cigarette smoking. By 1974 mortality from lung cancer in this group was roughly 4 -5 times greater than that in the general population. The incidence was higher among cigarette smokers, but adjustments for smoking did not account for most of the excess. (At present, many mining officials prohibit uranium miners from smoking while underground.) The mortality from lung cancer was much higher than that in other mining operations, such as coal and potash mining, where radiation levels are low. Other studies of miners working at intermediate to low levels of radiation show intermediate lung cancer risks. Non -malignant respiratory diseases were also high, as in other types of mining (77). Estimates of excess lung cancer mortality have been made for the current US maximum permissible exposure level in mining (4 WLM /a). For miners working 30 years, starting at 20 years of age, these range from 2.1 to 5.5 excess deaths up to age 80 per 10 000 man. a 1 of mining. This range

aOne WL is any combination of radon daughters in 1 litre of air which results in the ultimate release of 1.3x105 MeV of alpha energy. This numerical value is derived from the alpha energyeleased by the total decay of the short -lived daughter products in equilibrium with 10 µCi of radon -222 per litre of air.

48 depends upon whether the estimated risks from all levels of exposure are used or only those from the lower levels of exposure in the American study. As far as possible, assumptions made were checked by analyses of the data (77). Most respiratory cancer deaths occur 10 or more years after the start of mining (76). In a recent Czechoslovak study (78), covering on average 24 years of observation after the onset of the exposure, the exposure- effect relationship in the total group was not at variance with the assumption of a linear dose- response relationship. The presumption of direct proportionality of the exposure and effects yields 0.23 ± 0.04 lung cancer cases per 1000 workers per WLM as an estimate of average radiation risk. If the same "modified life table method" as in the USA study (73) is applied, the excess death rate from lung cancer in Czechoslovak uranium miners is about 30 deaths per 10 000 man a, or the excess death rate about 78 per 10 000 mana of mining. Whereas the technology needed to provide acceptable working conditions in uranium mines is available, it has been stressed (74) that ventilation alone will not reduce concentrations of radon daughters to much lower levels than those prevalent in 1969. As has been pointed out "studies of methods of reducing radon emission into working areas, more effective and more lasting means of closing off inactive areas, more acceptable respi- rators, and of removing radon from mine air might well result in further reductions in atmospheric contamination" (74). The radioactive materials in rock may produce external exposures of roughly 0.5 rem a-1. Thus, assuming (6) that 100 miners are involved in supplying uranium ore for a1 000 MW(e)a output, a collective dose of 50 manrem or 0.05 manrem per MW(e)a would result. The dose will depend on the percentage of open -pit mining, the grade of ore, the degree of mech- anization, etc. The accidental fatality rate in uranium mines in the USA was about 10 deaths per year per 10 000 miners over the period 1966 -76,a corresponding to an average of about 0.1 death per year for a 1 000 MW(e)a output. The tailings from uranium milling produce continuing releases of radon -222 which can result in the exposure of members of the general population (49, 80, 81, 82, 83). However, the problem can be minimized, for example, by covering the tailings with about 6 m of earth. This has been estimated (82) to reduce the radon emission by as much as 98 %. If the tailings pilings are exposed to weathering and leaching by water care must be exercised because the water runoff contains radium. In some cases in the USA the radioactivity of the river into which liquid tailings have been discharged may be 10 or more times the normal level (35). a Lundin, F.E., private communication (1976).

49 8.3 Fuel fabrication and enrichment In the fabrication of uranium fuel elements, the control of potential risks is relatively straightforward (84) and experience has shown containment procedures to be adequate. No appreciable discharge of radioactive material to the environment is to be expected, and there is little or no risk to the population. Exposure of operating staff is low. The introduction of plutonium- bearing fuels in thermal and fast reactors requires a high degree of containment because of the toxicity of plutonium (5, 85). In the handling and storage of plutonium and enriched uranium fuels, elaborate precautions are taken to prevent the possibility of over -accumulation which could lead to a criticality accident, giving potentially lethal levels of radiation in the working area.

8.4 Reactor operation

Exposure of populations during normal reactor operation comes mostly from controlled releases of radioactive materials, particularly fission products, discharged to the atmosphere. Far smaller amounts of radioactive materials (from induced activity in corrosion products, etc.) may be discharged with aqueous effluents. The magnitude and route of human exposure depend on the type of reactor; the radioactive content of the effluent depends on the delay, if any, before its discharge. During irradiation of the fuel, small amounts of some of the fission products which build up in the fuel leak through the cladding. This applies especially to the gaseous radionuclide such as tritium, isotopes of krypton and xenon and volatile compounds of carbon -14. In reactors using heavy water as moderator, some small proportion of the tritium produced can also leak into the atmosphere, and tritium is also produced where light water is used for cooling. In gas- cooled reactors (particularly the earlier designs) exposure of local populations occurs through the release of short -lived argon -41 (half -life 1.8 h) formed by irradiation of air used for cooling the reactor shielding. The collective dose to populations within 80 km of modern boiling water reactors from short -lived gases has been estimated to be 0.02 manrem per MW(e)a whereas the dose from gas -cooled reactors is about 0.04 manrem per MW(e)a. Pressurized water reactors release mainly xenon -133, the exposure within 80 km being estimated to be 0.01 manrem per MW(e)a (6). Various figures have been calculated for the average annual dose received by individual members of the population from worldwide nuclear reactor operation (49). For the USA a figure of 0.013 mrem has been reported and for the United Kingdom a figure of less than 0.003 mrem. These are less than 0.02% of the average natural radiation background. These figures lead (6) to overall estimates of about 0.1 manrem per MW(e)a from discharges into the

50 atmosphere and less than 0.01 manrem per MW(e)a from discharge of liquid waste. The total collective dose from all liquid discharges from reactors producing 3000 MW(e) of nuclear power in 1971 was estimated (49) not to exceed 3 manrem. Radioactive carbon -14 is at present released predominantly from reactors, with smaller amounts being released during fuel reprocessing. The radioactivity of carbon -14 released per 1000 MW(e) of power produced (-1 Ci) is many orders of magnitude lower than for krypton (3X 105 Ci)or tritium (2X 104 Ci). However, its very long half -life and its long circulation in the biosphere will cause it to accumulate slowly and cause irradiation at low dose rates for long periods of time. Assuming production of 50 Ci per 1000 MW(e)a, taking current atmospheric, hydrological and biological models and assuming total release of the carbon -14 formed, the collective dose commitment during the first 30 years has been calculated to be about 0.5 manrem per MW(e)a (6). Over 500 years the integrated collective dose commitment would be 1 manrem per MW(e)a. Further calculations extrapolated to the whole of future time yield a value of 10 manrem per MW(e)a for the limit of collective dose commitment from this source. Assuming formation of 30 Ci per 1000 MW(e)a, a collective dose extrapolated to infinity has been calculated to be 4.5 manrem per 1000 MW(e)a (86). All these values include the assumption (certainly over -pessimistic) that presently available or future technology will not be applied to reduce the releases. The Group felt it would be reasonable to assume 90% retention and suggested use in overall estimates a 500 -year integrated value of 0.1 manrem per MW(e)a. A wealth of data from a number of countries permits estimation of the exposure of workers in nuclear power plants, e.g., data published by the United Nations Scientific Committee on the Effects of Atomic Radiation ( UNSCEAR) (1). The UNSCEAR data, expressed in terms of power produced, show considerable uniformity between exposures from 20 reactors in six different countries despite variations in age, although the relative contributions from external and internal exposure show some differences. Much of the exposure in reactor operation is received during fuel replacement, maintenance and unscheduled repairs. Experience of the Working Group and published information led to a figure of 1 manrem per MW(e)a for the present contribution of whole -body occupational exposure (internal plus external) during reactor operations.

8.5 Fuel reprocessing

Exposure of populations from reprocessing plants comes partly from release to atmosphere of the most volatile radioactive materials (particularly fission products), still remaining at the time of full dissolution, and partly from discharges of low activity liquid effluents.

51 The main source of whole -body exposure is from the release of krypton - 85, and estimates of global exposure from thermal reactor fuel reprocessing are in the range 0.15 -0.2 manrem per MW(e)a (6) (for fast reactors 0.1 man - rem per MW(e)a). Lower exposures are expected from releases of tritium and other radionuclides (0.02 manrem per MW(e)a for thermal reactors and 0.02 manrem per MW(e)a for fast reactors (30)), the total exposure from all airborne releases being perhaps 0.25 manrem per MW(e)a. The very low activities of iodine -129 released contribute very small exposures to the thyroid gland. There are few major discharges of liquid waste from reprocessing plants to coastal waters. Calculations of population exposure from the amounts discharged is complex, depending very much on the local circumstances in the area of release and exposure pathways specific to that area. Examination of published information suggests that it would be reasonable to predict future collective population exposures by this route from the normal operation of reprocessing plants of the order of 0.2 manrem per MW(e)a. The reprocessing of nuclear fuels involves exposure of operating staff both to external radiation and to the risk of internal contamination, although most of the measured exposure is from external sources. In noting that the individual doses to workers in reprocessing plants are at present higher than those in the operation of nuclear reactors, the Working Group agreed that there was no reason why this exposure situation should be accepted. With improved design of reprocessing plants it should eventually be possible to reduce individual occupational exposures to the levels attained in reactor operation. Experience of the Working Group and published information led to an average of about 1 manrem per MW(e)a for present whole -body exposure from combined external and internal sources from fuel reprocessing.

8.6 Transport

Strict application of internationally recommended standards for transport operations (87) keeps radiation exposure of the general population and operators to very low levels. Figures of 0.03 and 0.005 manrem respectively per MW(e)a have been calculated (6).

8.7 Waste storage

The storage of waste materials and stocks of fuel and other radioactive products within nuclear sites is carried out in such a way that exposure of operators and the public is minimal. Storage and eventual disposal of waste on storage sites should also result in minimal exposure of operators and the public compared with exposure to other parts of the fuel cycle.

52 8.8Decommissioning of nuclear facilities

Radiation exposure of workers will occur during the dismantling of contaminated and activated components of redundant nuclear plants. The level will depend markedly on the techniques developed for remote operation and on design features incorporated in future reactors to ease dismantling. It is too early for anything but very crude estimates to be made but the Working Group accepted that a collective dose of about 1000 manrem might be received during the eventual dismantling of a large power station. This would lead, averaged over a 30 -year plant life, to a figure of 0.03 manrem per MW(e)a.

8.9Accidents to nuclear plants

The consequences of individual nuclear accidents have been discussed in Section 7. On the basis of the results of reactor safety studies it has been estimated (6) that accidents involving radiation might contribute to the total effects of the nuclear cycle, an annual average exposure of 0.05 manrem per MW(e)a.

8.10 Total radiation exposure from nuclear power programmes and consequent effects

The values derived above and in Section 7 for collective whole -body exposures and fatal accidents in the various stages of the nuclear fuel cycle a_ re summarized in Table 9. Within the limitations of the assessment, the total whole -body exposures to workers in the nuclear industry and to the public are 2.2 and 0.7 manrem per MW(e)a, respectively, whereas the genetically significant dose to workers and the general population are somewhat less, i.e., 0.6 and 0.3 manrem per MW(e)a, respectively. The generation of 1000 MW(e)a of electrical power from nuclear plants would entail, each year, an estimated collective dose commitment of some 3000 manrem of whole -body radiation, roughly three -quarters of which is received by the workers and the remaining one -quarter by the general population. The collective dose to the population would be made up of higher individual doses to relatively small numbers of people near the nuclear facilities and lower doses to a much larger number of people from widespread distribution through the atmosphere or water masses (88). The smaller genetically significant component of the collective annual dose commitment from 1000 MW(e)a of nuclearpower has been estimated to be about 900 manrem, of which two- thirds is received by workers in the industry. These estimates of whole -body and genetically significant dose commitment include extrapolation of the collective population exposure

53 from release of carbon -14 forward for 500 years. For carbon -14 a retention of 90% has been assumed. Assessments for other radionuclides are based on present practices and make no allowance for future and presently available technological improvements for reducing exposure of the general population and workers in the industry. When considering the incorporation of plant improvements to reduce already small population exposures, it must not be overlooked that this would almost inevitably increase occupational exposure still further as well as produce other forms of waste. It is necessary to evaluate the total impact of exposure and not only that affecting the general population. By combining these figures with the dose /effect relationships developed in Section 2, the possible total health effects from exposure to workers and the general population have been evaluated. The results of the evaluation indicate that the supply of 1000 MW(e)a of nuclear power (which would serve the needs of about a million people) would give rise to less than one malignant tumour; in about half the cases the cancer would be curable. For each 1000 MW(e)a of operation, less than 0.5 genetic defect on the average might be expected within a range of varying severity. In addition, workers in the industry would probably suffer on the average about 0.5 fatal accident and about 30 other disabling accidents not associated with radiation.

9. ENVIRONMENTAL EFFECTS

All industries, including all energy producing operations, have some impact on the environment. This section considers thermal effects (and their biological and ecological consequences) and chemical wastes. These are not unique to nuclear power plants; the environmental effects of fossil- fuel plants are further discussed in Section 11.

9.1 Thermal effects The discharge of warmed water from a nuclear power plant is no different qualitatively, and little different quantitatively, from that from conventional power plants. "Thermal pollution ", as it is sometimes called, refers to the accumulation of unwanted heat energy in any phase of the environment(89).Reviews of thermal effects inthe environment have currently been published(90, 91). The "spent" steam used to drive a turbine is condensed by cooling with large amounts of water. For the same electrical output, nuclear plants use more cooling water than modern fossil -fuel plants and produce about 20% more

54 waste heat (92, 90). The thermal efficiency of present nuclear plants is about 33 %, whereas future plants are expected to reach thermal efficiencies of about 35 -40 %. Under full load conditions the temperature of the cooling water coming from the outlet of a nuclear station is about 8 -10 degC above that of the inlet. This has to be taken into account if direct cooling by river, lake or sea water is considered. Various methods of heat disposal are employed (93) which can minimize the impact of thermal discharges upon such natural bodies of water; these include cooling towers, dilution in artificial lakes or canals (if sufficient land is available), water intake from deeper, cooler points, or the addition of cooler water before discharge (49).

Biological and ecological consequences. The environmental effects of thermal discharges depend on the size of the water -body receiving the warm water, its depth, movements, etc. Increased temperature may produce pro- found effects upon reproduction, growth, breeding habits, survival, and disturbances in the varieties of aquatic life at a given site. Increased temperature also reduces the solubility of gases in water; for example, between 20 °C and 30 °C the dissolved oxygen decreases by 17% (89), i.e., from 9.2 mg 1-' to 7.6 mg 1 -1. Simultaneously, the use of oxygen by organisms increases since the metabolic rate roughly doubles for a 10 degC rise in temperature. Mixing between the upper and lower layers of water may be inhibited by thermal stratification so that organic waste is kept separate from the higher amounts of oxygen contained in the upper layer; this leads to oxygen depletion in lower strata (90). One consequence of increasing metabolic rate with increasing temperature is a higher uptake of many radionuclides, e.g., caesium, cobalt, iodine and zinc. Concomitantly, the biological half -life of these radionuclides is reduced, resulting in a more rapid attainment of equilibrium concentration levels (57). Although some fish may favour warmer temperatures, generally few will survive above 30 °C. Their food supply, such as diatoms, decreases as the temperature rises above 20 °C and becomes replaced by the less desirable and often toxic blue -green algae. Above 35 °C nearly all the diatoms disappear. Hence, at temperatures of 30 -35 °C a water -body is essentially a biological desert (89). For these and other reasons, as for example the scouring effect of the discharged water on the bottom characteristics, regulatory agencies in different countries have imposed strict limits on cooling water discharges. Beneficial effects of the discharged warm water (91) include the use of heated effluents to maintain optimal temperatures for growth and high yields of fish and other seafood, warm water irrigation, soil heating and protection of crops, and district heating. Detailed information on the biological and ecological effects of thermal discharges is available (27, 28, 49, 50, 51, 53, 57, 89, 90, 91, 94, 95).

55 Climatic effects. Some evaporation of cooling water takes place in a wet cooling tower; it can be expedited by blowing air through the sprays of water inside the tower. Discharges of water into the atmosphere at temperatures above that of the air can result in localized effects, e.g., fog, ice formation on trees, roads and transmission lines (90). Chemicals added to the water in cooling towers to inhibit the growth of organisms can be transported and may have adverse environmental effects (49). Because of the environmental impacts of wet cooling towers (direct water/ air contact), dry air cooling towers with closed loop water transport are being considered in many places despite higher costs and greater land requirements.

9.2 Chemical waste The control of chemical effluents is important in both nuclear and fossil- fuelled power production, as well as in other industrial operations. Although the means exist to control chemical effluents, available technology is not always utilized to the best advantage for meeting acceptable limits. Numerous chemicals are used during the operations of fossil -fuel and nuclear power plants (96). These include those used for corrosion control, such as mixtures of chromate, zinc, phosphate and silicates. Microbial growth is controlled by additives to the water in the cooling towers such as chlorine, hypochlorites, chlorophenols, quaternary amines and organometallics. The pH of water is controlled by acids and alkalies. Silt deposition may be reduced by the use of polymers such as lignin- tannin dispersives, polyacryla- mides,polyacrylates and otherpolyelectrolytes. An extensivelistof chemicals associated with nuclear power plants and their effects on test organisms is included in 96. Non -radioactive waste from the nuclear fuel cycle (see Fig. 2) includes oxides of nitrogen and sulfur, fluorides, sulfates, inorganic salts of calcium and iron, sodium chloride, nitrates and ammonia. Maximum safe levels and regulations for the disposal of these chemicals are usually set by governmental authorities (97).

10. PROLIFERATION OF NUCLEAR EXPLOSIVES, SABOTAGE AND TERRORISM

Proliferation of nuclear explosives must be seen in two different contexts: that of a possible increase in the number of sovereign nations that have access to atomic weapons, and that of sub -national groups obtaining and using nuclear explosives for terrorist purposes.

56 Regarding the question of the proliferation of nuclear weapons, the Working Group noted the status of the Treaty on the Non -Proliferation of Nuclear Weapons, now ratified by 100 nations, and the efforts of nuclear export countries concerning coordination of measures to assist in reducing probabilities of international proliferation. Taking into account the increasing amounts of fissile material expected to be handled in the future, the Working Group pointed to the importance of continued efforts to minimize a possible risk to the public from illegal future diversion of materials from the nuclear fuel cycle. Individual governments and international organizations are developing stricter measures for physical protection and control of fissile material in use, transit, or storage(98, 99, 100). Many assessments have been made of the effort needed to construct a nuclear weapon if the necessary material has been acquired. These assessments range from a few man -months(79, 101)to tens of man -years(102) of highly skilled effort. One study(102)has concluded that theft of a nuclear weapon from one of the nuclear weapon states represented the greater risk. Studies of the susceptibility of nuclear facilities to sabotage for a broad range of threats have been made(103, 104, 105).These studies point out that such plants appear far less susceptible to sabotage than most other civil industrial targets. Evaluations of probable consequences following sequences of sabotage actions conclude that they are likely to be small fractions of the maximum consequences for reactor accidents yielded by the American RSS (Section 7). The consequences of wilful dispersion by terrorists of a plutonium aerosol in densely populated areas could be serious. The health consequences of such dispersion have been the subject of several studies(104, 106).For realistic scenarios, inhalation of the cloud appears to be the main risk following dispersal, causing eventually approximately 0.05 death per gram of plutonium dioxide dispersed(106).Local areas could become contaminated to such an extent that limited evacuation followed by decontamination would be necessary. It has been estimated(107)that for relatively small amounts dispersed, the costs of decontamination could run into millions of dollars. Since most health effects of the dispersal will be delayed by 15 to 45 years, and because of the difficulty of executing this type of terrorist act, itis concluded that plutonium dispersal would probably represent a very small part of the overall risk from acts of terrorism. One perspective on the dispersion of plutonium is obtained from the observation that, as a result of nuclear weapons tests, some 5 t of plutonium have been dispersed in the atmosphere(108).If this were evenly distributed in the world's population each person would have accumulated a body burden in excess of 1 mg; in fact measured plutonium body burdens are tens of millions of times lower than this(109).

57 One recent study(105)has indicated the possible usefulness of quantitative decision theory in evaluating the potential economic and social risks of nuclear terrorism and sabotage. The Working Group concluded that, although there is no way of obtaining absolute assurance against terrorist thefts of radioactive materials which may be used for the production of a nuclear device, or against nuclear plant sabotage, any risk to the public from such acts would not contribute substantially above that already existing in contemporary society from other similar threats. It was also concluded that reducing the rate of nuclear power development would not substantially reduce the overall possibility of terrorist threats. However, the Group emphasized the importance of continued efforts to minimize the possibility of risk from plutonium diversion and sabotage of nuclear plants.

11. CONSIDERATION OF HEALTH EFFECTS FROM NUCLEAR AND ALTERNATIVE ENERGY PRODUCTION SYSTEMS

A meaningful perspective on the health and environmental effects of nuclear power can only be obtained by comparing them with alternative means of energy production. Comparative assessments are also needed as a basis for rational and cost /effective safety and control procedures. The main alternatives to nuclear power generation are at present coal- and oil -fired power plants.

11.1 Public health effects

The increasingly stringent effluent controls for fossil- fuelled power plants will presumably lead to future reductions of the health effects per unit of electricity produced from these plants. Future technology could lead to substantial reductions in the emission of a number of the toxic chemical pollutants (Table 11 and ref.110).In addition to the pollutants listed in the Table, about 30 trace elements present in coal are released during combustion. Several of these elements are toxic, including beryllium, mercury, arsenic, cadmium, lead, vanadium, and nickel. Attempts have been made to relate air pollution to various health effects(19, 40, 111, 112, 113, 114, 115, 116).In the absence of reliable data at low pollutant exposures, a threshold -type relationship is generally assumed for acute and chronic diseases caused by air pollution. However, as in the case of radiation, a non -threshold relationship is generally assumed for genetic and carcinogenic effects(117).

58 Table 11.Annual releases of chemical pollutants from 1000 MW(e) fossil -fuelled power stations'

Total annual emissions (per 1000 t) Pollutants Coalb Oilc

Aldehydes 0.052 0.12 Carbon monoxide 0.52 0.0084 Hydrocarbons 0.21 0.67 Nitrogen oxides 21 22 Sulfur oxides 139d 53 Particulate matter 4.58 0.7

aModified after Terril et al. (118). b Represents the burning of about 2.1x106 t a 1of semi -bituminous coal.

cRepresents the burning of about 1.7x105 m3 a-1 of oil with an assumed ash content of 0.05% and 1 .6% sulfur content by weight (present sulfur values are closer to an average of about 0.7% (113)). The emissions given here assume the operation is carried out with no pollution control. d Assuming 3.5% sulfur content, of which 15% remains in ash.

Assuming 9% ash content and 97.5% fly ash removal efficiency.

A number of estimates of possible fatalities among the members of the general population have been made. A recent survey of these estimates (111) concludes that the number of premature deaths from emission from fossil - fuelled power plants may be considerably higher than for nuclear plants. However, the uncertainties in these estimates are considerable, as shown by the wide range of the number of estimated deaths (e.g., for one year of operation of a 1000 MW(e) coal -fired station, 1.6 -111 deaths), and true comparisons with nuclear power are difficult. A difficult problem in evaluating health effects of emissions from fossil - fuelled power plants is the identification of the individual contributions, if any, of the various chemical pollutants, bearing in mind the known syner- gistic effects of, for example, suspended particulates, ozone and nitrogen oxides. An additional complication is the unknown influence of the chemical and physical nature of the suspended particulates. Sulfur dioxide, in combination with particulate matter, has generally been believed to represent the main health hazard from fossil -fuelled power plant

59 emissions. Thus, air quality standards usually include limits on sulfur dioxide to protect human health. The safety margins on some of those standards appear to be small. The standards have been set in a range of pollutant concentrations where adverse health effects appear to be perceivable. These are described as ranging from "discomforts, through physiological deviations from the norm, prevalence of symptoms, appearance of illness, lost working time and premature retirement, to complete incapacity and death" (119). It is now being increasingly realized that sulfur dioxide concentrations are probably not the best indication of the health hazard from sulfur pollution. Rather, sulfate or sulfuric acid particles, to which atmospheric sulfur dioxide is converted, are believed to be the most important harmful agents. It is clear that the safety margins for fossil- fuelled plant emissions (in terms of those levels producing readily detectable health effects) are much smaller than those for radiation from the nuclear fuel cycle.

11.2 Occupational health effects

Statistical information isavailable on accidents involving death or injury for workers in the nuclear, coal and oil power production industries, including mining operations. A survey of this information has been made (111) and respective data are presented in Table 12, together with the Working Group's estimate for the nuclear power industry.

Table 12.Occupational accidental deaths from 1 year of operation of a 1000 MW(e) electrical power plant and associated fuel cycle services'

Fuel Occupational accidental deaths/3

Coal 0.54-5 Oil 0.14- 1.3 Nuclear 0.01- 0.86 ^'0.3e

a Data on accidents during construction of installations are not included because of lack of data for fossil -fuelled power plants.

bThe ranges shown are the lowest and highest estimates from four studies cited (111). C The figure is taken from Table 9. It does not include occupational fatalities during construction.

60 11.3 Radioactivity from plants utilizing fossil fuels

The fly ash from coal- and oil- fuelled plants contains trace quantities of uranium and thorium and their radioactive decay products, especially radium -226 and radium -228. The actual amounts depend on the efficiency of fly ash removal and the composition of the coal. The quantities of radium released by an oil -fired power plant are much less, because oil fly ash contains about a tenth as much radium as coal fly ash and, in addition, coal has a higher ash content than oil(120).The radiological exposure from fossil- fuelled plants is small, corresponding (per MW(e)) to somewhere in the range of 1 part per 10 8 of the ICRP recommended limits as determined from field measurements(120).A number of comparisons have been made between the radiological health impacts of fossil -fuel and nuclear power generation plants(112, 120).Generally, it appears that with present technology the health effects from airborne radioactivity from coal -fired power stations is less than that from boiling water reactors and larger than that from pressurized water reactors. The radiological impact of liquid effluents from coal -fired plants (including that from waste) does not appear to have been evaluated, but is expected to be far less than that from nuclear power plant liquid effluents.

11.4 Environmental impacts

Generally, the land areas required for power plants and fuel mining and production are smaller for nuclear plants than for fossil -fuelled plants (121). Whereas large nuclear power plants generally require the equivalent of less than 70 truck transports of fresh and spent fuel per year, fossil -fuelled power plants of similar output require transport by ship or rail of 1.5- 2.5X106 t a' of fuel. Movements of waste from fossil- fuelled plants will vary substantially with solid waste handling procedures. Thus the environmental impact of fuel and waste transportation systems will be markedly greater for coal- and oil -fired plants. As is well known, the environmental impact of emissions into the air from fossil -fuelled power plants can be substantial over large regions. Suchan impact is mainly determined by acid precipitation (caused by oxides of sulfur and nitrogen) and includes increased acidity of lakes, rivers and soil, with consequent effects on aquatic life forms and on the composition and growth rates of vegetation. Releases of radioactivity from fossil -fuelled and nuclear plants probably have no environmental impact. Rejection of waste heat from nuclear and fossil -fuelled plantsare similar, the nuclear plants generally releasing about 20%more waste heat to water than fossil- fuelled plants. In certain locations, increase in the temperature of cooling water can lead to substantial local impacts on aquaticcon- ditions.

61 Climatic effects of fossil- fuelled and nuclear power plants can be caused by waste heat releases, which generally are only of local importance(122), and for fossil -fuelled power plants on a global scale by release of carbon dioxide(123, 124).The global temperature increases that could be caused by carbon dioxide releases from fossil -fuelled power plants are, however, counter- acted by accompanying releases of dust and fly ash. It has, for example, been estimated(122)that there would be a global average temperature increase of about 5 degC in the period 1980 -2050 if the energy needs of the world population were met largely by fossil- fuelled power plants. Such estimates are subject to major uncertainties due to insufficient data and knowledge.

11.5 Alternative energy production systems

The main future large -scale alternatives to present energy production systems appear to be nuclear fusion and solar energy. Even if successfully developed, these alternatives will also have health and environmental impacts (125). Possible future nuclear- fusion power plants will, at the end of their lives, produce large volumes of solid radioactive waste which will require disposal or safe storage for generations. Some release of radioactivity during operation appears inevitable(126),tritium almost certainly presenting the main radiological health hazard from nuclear- fusion power plants. Radio- active waste production is, however, expected to be substantially less than that from nuclear -fission power plants. Electrical power production plants using solar energy could introduce substantial environmental effects due to the large land area required. Produc- tion of the materials required for such large plants, their maintenance and operation, the required transmission systems, and plant decommissioning entail possible health consequences which are difficult to evaluate in the absence of more detailed plant designs and information on operations and waste handling procedures. Other proposed commercial sources of power, the wind, waves, tides and geothermal energy, will certainly not be without risks and environmental impact. However, since quantitative predictions of health and environmental impacts of all these possible future sources of power cannot yet be made owing to lack of information on plant design and operational procedures, a meaningful comparison of impacts with existing power production systems is not possible.

11.6 Conclusions

62 and future). In such assessments, data should be treated on an equivalent basis, i.e., for equal energy output and for the complete cycle of operations. Indeed, estimates of harm should be compared with what would result from failure to develop necessary additional power by any of the alternative means. Since knowledge of the health effects of alternative sources of energy (e.g., fossil fuels) is generally less precise than that of radiation effects, it was recommended that available information be critically reviewed and appropriate research conducted on the health effects of alternative energy sources. A recent review (127) suggests the priorities which should be given to any future research on health effects of fossil fuels.

12. PUBLIC INFORMATION

Nuclear power has been introduced into several countries without giving rise to public discussions or controversy. In many countries, however, there is increasing public debate on the acceptability of nuclear power. Public and private organizations are providing the public with increasing amounts of often conflicting information on all aspects of the growth of nuclear power. Health effects of radiation from the nuclear fuel cycle are a prominent concern in the public debate. The Working Group stressed the importance of early and continuous dissemination to the public of full and factual information on the likely consequences of operating nuclear power plants, including comparison with alternative power production sources. Public health authorities would be expected to participate in the dissemination of such information. International organizations should play an important role in the dissemination of information on nuclear energy and should contribute to the general awareness and confidence of the public.

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68 84. International Atomic Energy Agency. Radiological safety requirements for fuel fabrication plants. Report of an Advisory Group meeting, December 1975 and August 1976, Vienna (in press) 85. US Environmental Protection Agency. Health effects of alpha- emitting particles in the respiratory tract. Washington, DC, 1976 (EPA 520/4 76 -013) 86. Pochin, E.E. Occupational and other fatality rates. Community Health, 6: 2 (1974) 87. International Atomic Energy Agency. Regulations for the safe transport of radioactive materials.Vienna, 1973 (Safety Series No. 6 (rev. ed.)) 88. US Atomic Energy Commission. The potential radiological implications of nuclear facilities on the Upper Mississippi River Basin in the year 2000. Washington, DC, 1973 (WASH -1200) 89. Cole, L.C. Thermal pollution. Bioscience, 19: 989 -992 (1969) 90. Parker, F.L. Thermal pollution and the environment. In: Industrial pollution. London, Van Nostrand Reinhold, 1974, p. 150 91. International Atomic Energy Agency. Environmental effects of cooling systems and thermal discharges at nuclear power plants. Vienna, 1975 (STI /PUB /3 78) 92. Cohen, B.L. Nuclear science and society. Garden City, NY, Anchor Books, 1974 93. International Atomic Energy Agency.Environmental effects of cooling systems at nuclear power plants. Vienna, 1975 (STI /PUB/ 378) 94. International Atomic Energy Agency. Thermal discharges at nuclear power stations. Vienna, 1974 (Technical Report Series No. 155) (STI/ DOC/ 10/ 155) 95. International Atomic Energy Agency. Combined effects of radioactive, chemical and thermal releases to the environment. Vienna, 1975 (STI/ PUB /404) 96. Becker, C.D. & Thatcher, T.O. Toxicity of power plant chemicals to aquatic life. Richland, WA, Battelle Pacific Northwest Laboratories, 1973 (WASH -1249) 97. Casarett, L.J. & Doull, J., ed. Toxicology. London, Macmillan, 1975 98. International Atomic Energy Agency. The physical protection of nuclear material. Vienna, February 1976 (INF.CIRC /225) 99. International Atomic Energy Agency. Safeguarding nuclear materials. vol. I & II. Vienna, 1976 (STI /PUB /408) 100. International Atomic Energy Agency. International treaties relating to nuclear control and disarmament. Vienna, 1975 (Legal Series No. 9) (STI /PUB /387) 101. Wilhich, M. & Taylor, T.B. Nuclear theft: risks and safeguards. Cam- bridge, MA, Ballinger, 1974

69 102. Gyldén, N. & Holm, L.W. Risks for illegal production of nuclear explosives. Stockholm, FOA 4 Report (C4567 -T3) (in Swedish) 103. US Nuclear Regulatory Commission. Safety and security of nuclear power reactors to acts of sabotage. Nuclear Safety, 17: 665 (1976) 104. Chester, C.V. Estimates of threats to the public from terrorist acts against nuclear facilities. Nuclear Society, 17 (6): 659 (1976) 105. Barragher, S.M. et al. The economic and social costs of coal and nuclear energy generation: a framework for assessment and illustrative calculations for the coal and nuclear fuel cycles. Stanford Research Institute Report to the National Science Foundation, Menlo Park, CA, 1976 106. Cohen, B.L. The hazards in plutonium disposal. Oak Ridge, Institute for Energy Analysis, 1975 107. Duchene, A. et al. The role of measurement in the assessment of third party liability following an accidental release of plutonium to the public environment. In: Recht, P. & Lakey, J.R.A. ed. International Symposium on Radiation Protection Measurement. Aviemore, Scotland, July 1974. Luxembourg, Commission of the European Communities, 1975 (EUR 5397e) 108. US Atomic Energy Commission. Draft environmental statement: liquid metal fast breeder reactor program. In: Environmental impact of the LMFBR. Washington, DC, 1974, vol. II (WASH -1535) 109. US Atomic Energy Commission. Fallout program quarterly summary report. Washington, DC, 1974 (Report HASL -278- Appendix) 110. Chang, B. & Wilson, R. Mitigation of the effects of sulphur pollution. Cambridge, MA, Harvard University Energy and Environmental Policy Centre, 1976 111. Comar, C.L. & Sagan, L.A. Health effects of energy production and conversion. Annual Review of Energy, p. 581 (Jan. 1976) 112. Lave, E.B. & Freeburg, L.C. Health effects of electricity generation from coal, oil and nuclear fuel. Nuclear Safety, 14: 409 (1973) 113. Hub, K.A. & Schlenker, R.A. Health effects of alternative means of electrical generation. In: Population dose evaluation and standards for man and his environment. Vienna, International Atomic Energy Agency, 1974 (STI /PUB /375) p. 463 114. Hamilton, L.D. & Morris, S.C., ed. Health effects of fossil fuel power plants. In: Symposium on Population Exposures. Knoxville, TN, 1974 115. US Senate Committee on Public Works. Air quality and stationary source emission control. Washington, DC, 1975 (Serial No. 94 -4) 116. Norwegian Institute for Air Research. Air pollution health effects of electric power generation. Kjeller, Norway, Institutt for Atomenergi, 1975 117. Air pollution and cancer, risk assessment methodology and epidemiological evidence. Report from an International Symposium at the Karolinska Institute, Stockholm, 8 -11 March 1977. Environmental Health Perspectives (in press)

70 118. Terrill, J.G. et al. Environmental aspects of nuclear and conventional power plants. Indust. Med. & Surgery, 36: 412 (1967) 119. Rall, P. A review of the health effects of sulphur oxides. Research TrianglePark, NC, NationalInstituteof Environmental Health Sciences 120. Martin, J.E. et al. Radiation doses from fossil -fuel and nuclear power plants. In: Berkowitz, D.A. & Squires, A.M., ed. Power generation and environmental change. Cambridge, MA, MIT Press, 1971 121. Council on Environmental Quality. Energy and the environment: electric power. Washington, DC, 1973 122. Schmidt, F.H. & Bodonsky, D. The fight over nuclear power. University of Washington, WA, 1976, Appendix B 123. Mitchell, J.M. A preliminary evaluation of atmospheric pollution as a cause of global temperature fluctuations in the past century. In: Singer, F., ed. Global effects and environmental pollution. 1970 124. Niehaus, F. A non -linear eight level tandem model to calculate the future CO2 and C -14 burden to the atmosphere.Laxenburg, Austria, International Institute for Applied Systems Analysis, 1976 (RM- 76 -35) 125. Flakus, F.N. Fusion power and the environment. Atomic Energy Re- view, 13 (3) (1975) 126. Kulcinski, G.L. Fusion power - an assessment of its potential impact in the USA. Energy policy, June 1974, p. 104 127. Comar, C.L. & Nelson, N. Health effects of fossil fuel combustion products: report of a workshop. Environmental Health Perspectives, 12: 149 (1975)

71 Annex I

DEFINITIONS OF "RISK ", "DETRIMENT ", AND "COLLECTIVE DOSE" (From ICRP Publication 22 (32), where the present term "collective dose" was referred to as "population dose ")

Risk (R) In this report the word "risk" is used to mean the probability that a given individual will incur a deleterious effect as a result of a dose of radiation. If pi is the probability of suffering the ith effect, then R = 1 - 7ri(1 - pi). When the different effects are mutually exclusive, the expression mentioned above reduces to R = Epi. This simplified formulation would also be approximately correct when all piG < <1, even if the effects are not mutually exclusive.

Detriment (G)

The "detriment" in a population is defined as the mathematical concept "expectation" of the harm incurred from a radiation dose, taking into account not only the probabilities of each type of deleterious effect, but the severity of the effects as well. Thus, if pi is the probability of suffering the effect i, the severity of which is expressed by a weighting factor gi, then the detriment G in a group composed of P persons is G = P Eipigi.

Collective dose

This is a measure of the total exposure of the whole body or a specified organ of a population of people. If the number of people receiving doses between H and H +dH is N(H) dH, the collective dose is given by the integral: f H N(H) dH, where the integration is carried out over the total dose distribution over the world population. In some cases, it may be useful to identify a component of the collective dose related to a given sub -population, which, for some purposes, may be the population of a country or a region. This component may then be called the collective dose for that sub -population.

72 Annex II

PARTICIPANTS

Temporary Advisers

Mr G. Bresson, Deputy Chief, Radiation Protection Department, Atomic Energy Commission, Fontenay -aux- Roses, France Dr P. Courvoisier, Chief, Nuclear Safety Division, Federal Office of Energy, Würenlingen, Switzerland Dr P. Czerski, Associate Professor and Head, Department of Genetics, National Research Institute of Mother and Child, Warsaw, Poland (Co- Rapporteur) Dr P. Dejonghe, Head, Division of Applied Research, Nuclear Energy Research Centre, Mol, Belgium Dr J.M. D$derlein, Director, Safety Technology Division, Institute for Atomic Energy, Kjeller, Norway (member of drafting committee of final report) Dr M. Faber, Professor and Director, Finsen Laboratory, Finsen Insti- tute, Copenhagen, Denmark Dr S. Halter, Chief Medical Officer, Ministry of Public Health and Family Welfare, Brussels, Belgium Dr V. Klener, Head, Centre of Radiation Hygiene, Institute of Hygiene and Epidemiology, Prague, Czechoslovakia Dr E. Komarov, Deputy Director, Central Research Institute of Roent- genology and Radiology, Leningrad, USSR (Vice- Chairman) Dr P. Korringa, Director, Netherlands Institute for Fishery Investiga- tions, Ijmuiden, Netherlands Dr A. Lafontaine, Professor and Director, Institute of Hygiene and Epi- demiology, Brussels, Belgium Dr B. Lindell, Professor and Director, Swedish National Institute of Radiation Protection, Stockholm, Sweden (Chairman) Dr B.A.J. Lister, Head, Nuclear Environment Branch, Atomic Energy Research Establishment, Harwell, Didcot, United Kingdom (member of drafting committee of final report)

73 Dr F.E. Lundin, Chief, Epidemiology Studies Branch, Division of Bio- logicalEffects, Bureau of Radiological Health, Department of Health, Education and Welfare, Rockville, MD, USA Dr P. Oftedal, Professor, Institute for General Genetics, University of Oslo, Norway Dr E.E. Pochin, National Radiological Protection Board, Harwell, Didcot, United Kingdom Dr J. Schubert, Professor of Environmental Health Sciences, Division of Natural Sciences, Hope College, Holland, MI, USA (Rapporteur and member of drafting committee of final report) Dr. J. Schwibach, Institute for Radiation Protection, Neuherberg, Federal Republic of Germany Mr P. Tanguy, Head, Nuclear Safety Department, Nuclear Energy Centre - Saclay, Gif- sur -Yvette, France

Representatives of Other Organizations

Commission of the European Communities

Mr H. Eriskat, Chief of Service, Directorate for Health Protection, Luxembourg

International Atomic Energy Agency

Dr F.N. Flakus, Radiological Safety Section, Division of Nuclear Safety and Environmental Protection, Vienna, Austria

International Commission on Radiological Protection

Dr B. Lindell (of the Swedish National Institute of Radiation Protection, Stockholm, Sweden)

International Radiation Protection Association

Dr A. Lafontaine (of the Institute of Hygiene and Epidemiology, Brussels, Belgium)

74 Organisation for Economic Co- operation and Development

Dr B. Rüegger, Administrator, OECD Nuclear Energy Agency, Paris, France

World Health Organization

Regional Office for Europe

Dr M.J. Suess, Regional Officer for Environmental Pollution Control (Scientific Secretary)

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