Management of radioactive wastes

Annals of Nuclear Energy, Vol. 3, pp. 285 to 295. Pergamon Press 1976. Printed in Northern Ireland

MANAGEMENT OF RADIOACTIVE WASTES W~l. L. LENNEMANN, H. E. PARKER and P. J. WEST International Atomic Energy Agency Vienna, Austria Summary--There are several areas of current concern either bordering on or regarding radioacitve waste management in the nuclear fuel cycle. These areas have local, regional and global aspects and require either immediate attention or preparation for future implications. Those areas requiring immediate attention are better management and control over mill railings, a shortage of irradiated fuel storage space, and decommissioning criteria. Fuel storage should be recognized as a viable alternative to reprocessing for at least the next decade and suitable storage space incorporated in nuclear reactor facilities. Regulatory bodies should establish decommissioning criteria which then should be taken into account during the planning and design of a nuclear facility. Areas indicating future implications are removal and confinement of gaseous radionuclides, particularly tritium and krypton-85. There is now also some concern regarding carbon-14 which should be investigated. Resolving the high-level and alpha-bearing waste disposal question seems to be one of the most serious problems and highest priority objectives facing the nuclear industry today. Use of suitable geologic formations appears to be the only technology which will be available for the next several decades. The alternative is surface storage in engineered facilities which does not finally answer the question. Consequently, demonstrating the disposition of high-level and alpha-bearing wastes in suitable geologic formations should proceed without delay. International co-operation in the establishment and use of regional centres rather than having a proliferation of local facilities for fuel reprocessing should facilitate significantly the management of the resulting radioactive wastes. It also would reduce the hazards associated with having a large number of sources for radioactive releases. Nuclear power programmes can come closer to maturity through international co-operation in resolving the waste disposal question and minimizing the number of facilities involved in fuel reprocessing and radioactive waste management. INTRODUCTION The radioactive wastes that are generated in the various sectors of the nuclear fuel cycle have been characterized to include uranium mine dumps, mill tailings, low-level liquid and solid wastes, gaseous wastes, high-level wastes and wastes contaminated with plutonium and other actinides. There also is a rather nebulous category of intermediate-level wastes which indicates either one of the two following things: (a) that some manner of processing is worthwhile from either an economics standpoint or some other reason, concentrating the radionuclides in the waste into a small fraction of the original volume for storage and permitting the controlled release or discharge of the bulk of the material, or

(b) its level of radioactivity is such that it cannot be freely released into the environment but can be managed in a manner that takes advantage of environmental barriers to the spread of radioactivity, such as using seepage basins or solid waste burial. High-level wastes, for purposes of this presentation, are those wastes that contain concentrations of Paper presented at the European Nuclear Conference, Paris, April 1975.

radionuclides to the extent that they cannot be discharged to the environment but have to be isolated from the biosphere for long p e r i o d s - - a t least until the radionuclides have decayed to innocuous concentrations. High-level wastes indicate high-levels of radioactivity, resulting in heat generation rates which complicate their management. On the other hand, there are wastes contaminated with plutonium and other long-lived actinides, the so-called alpha-emitters, which are neither highly radioactive nor require special measures for heat dissipation but are highly toxic when introduced into body tissue. Consequently, wastes contaminated with the long-lived alpha-emitters, a typical example being plutonium-239 with a half-life of about 24,000 yr, must be safely confined under surveillance for very long periods of time or disposed of in a manner that has a very high probability of their presence never becoming hazardous to man or his environment. Uranium-233, an alpha emitter, generally is contaminated with uranium-232 which itself does not emit troublesome radiation but some of its daughter products do, building up to relatively high levels of radioactivity rather rapidly. Assuming that most of you here probably are involved in some way with radioactive waste management and have kept abreast of the developments in this field, there would be a redundancy in 285

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W . L . LENNEMANN,H. E. PARKER and P. J. WEST Ore

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reviewing the origins of radioactive wastes and the techniques being used to manage them. Consequently this paper will discuss where we, the authors, feel there are soft spots in radioactive waste management along with some opinions of the challenges which the nuclear power industry must face in these areas. It will cover some pertinent data which was developed during a recent cursory study made by the staff of the International Atomic Energy Agency (Agency) to estimate the benefits that might be derived from regional centres to handle nuclear fuel reprocessing and the resulting radioactive wastes. Finally, it will summarize some possibilities for strengthening the soft spots. NUCLEAR

FUEL

CYCLE

Safe operation of a nuclear reactor is not the end of nuclear responsibilities. Nuclear fission breeds responsibilities, some with long half-lives. Nuclear power programmes require consideration not only of the power plants, their siting and operation, and planning for the nuclear fuel supply but also of what is to be done with the irradiated fuels and the nuclear waste in them. There have to be decisions on spent fuel management, whether the fuel is to be stored and]or reprocessed--when and where, on having the appropriate facilities and technical competence

available when needed, on the management and disposition of the radioactive wastes resulting from any fuel reprocessing, and on the safeguarding and utilization of the nuclear materials recovered from reprocessed fuels. Figure la is one way of schematically illustrating the nuclear fuel cycle. Irradiated fuel storage normally has not been included as part of the cycle but it has been included in Fig. la because, today, fuel storage may become a viable option prior to reprocessing the fuel at some later time. The shaded areas of Fig. lb indicate where we believe there are immediate and future areas of concern in the nuclear fuel cycle operations, essentially all involving radioactive waste management. In addition, there is decommissioning which applies to all fuel cycle facilities. Besides their temporal aspects, these areas of our concern have spatial implications thus giving a need to consider their local, regional and global aspects. Local aspects in waste management have to do with impacts from local activity such as management of mill tailings at uranium mills, the effects of releases from a nearby nuclear facility and storage and disposal sites for radioactive waste. Regional aspects have to do with impacts from a network of nuclear activities, including those that extend beyond governmental boundaries. The

Management of radioactive wastes principal concerns in this area include the development of methodology to assess impacts from many sources, and, by assessing any detriment to the environment to point the way to necessary waste management, controls and standards. Another matter for consideration is the formulation and implementation of regional plans for the management of high-level and alpha-bearing radioactive wastes, particularly from nuclear fuel reprocessing. It seems probable that of the total 3500 GWe* nuclear generating capacity that is estimated to be operational by the year 1990, 3000 GWe will be located in about ten countries that will have fuel reprocessing facilities. The remaining 500GWe will be located in a larger number of countries spread all over the world. The questions that arise in respect to these countries are: Will they opt for the reprocessing of their nuclear fuel themselves or by contract to those countries with reprocessing facilities ? Who is to be responsible for the disposal of the radioactive wastes ? What are the liabilities involved ? Will they sell their irradiated fuel as a resource material to reprocessing countries? Or, will they opt for the discard of irradiated fuel elements as a radioactive waste? Whatever the answers to these questions may be, there would seem to be an advantage in international co-operation with regard to the safe management of the radioactive materials. Global aspects result mainly from releases of radionuclides of global significance such as tritium, krypton-85, and possibly iodine-129 from the nuclear fuel cycle. Carbon-14 may be another. The rapid growth of nuclear power throughout the world and the consequent growth in fuel reprocessing operations may eventually lead to requirements for the control of releases of these radionuclides to the environment as gaseous wastes; and waste management technology then will have to provide for the isolation from the biosphere of a major portion of these radioactive waste products. Disposal ot radioactive v,'astes into the seas is another activity with potential global significance. Whether the foregoing areas are of immediate or future concern will become apparent during their discussion. MILL TAILINGS The residual activity in mill tailings is due chiefly to naturally occurring radium-266. Although its concentration in mill tailings is very low, about 800 pCi/g, it is of concern because of its long half-life (1620 yr) and associated decay products. Radon gas * It now appears that this estimate is somewhat optimistic but it is retained for illustrative purposes.

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from the decay of radium-226 can diffuse outwardly from those tailings. Consequently, there is general agreement that such railings should not be used either in structural materials or in backfill material in connection with buildings for human occupancy. Thus, there is a need for long-term control and surveillance of uranium mill tailings. The radiation from uranium mill railings does not present a serious health hazard in open, wellventilated areas or outside. Nevertheless, the hazard will persist for thousands of years. Consequently, location and disposal of tailings must be planned and engineered with the foregoing and permanence in mind. When use of a particular tailings disposal area ceases, it should be stabilized and revegetated to the extent feasible with protection from water and wind erosion. Its location should be well marked as permanently as possible and registered with local land authorities and with appropriate restrictions in perpetuity being placed on use of the area. FUEL STORAGE A tacit assumption seems to have been that when the spent fuel is discharged from a reactor, fuel reprocessing and waste management services will be, or soon will become, available at charges which would be compenstated for by the value of the recovered fissible material. Furthermore, there has been the assumption that the reprocessor of the fuels would provide all of the necessary waste management services arising from the reprocessing to the extent that those concerned with reactor operations no longer would be involved with responsibilities for managing these wastes. The charges for the waste management services would be included in the fuel reprocessing charge. Except for the heavy water reactors using natural uranium fuels, there seems to have been little thought given to situations where fuel reprocessing services either may not be available or are economically unattractive. Consequently, for either one of these two reasons, there are indications that a shortage of fuel storage space is becoming a pressing problem requiring immediate attention. While irradiated or spent fuel is not regarded in most nuclear economies today as a waste, the management of it while in interim storage is not unlike the management of solidified high-level waste. All the heat generating fission products are there, even more plutonium, and, in addition, the gaseous nuclides, tritium, iodine and krypton. While the container and the fuel form may not meet the waste manager's goals for solidified high-level waste, they have withstood rather brutal treatment in the

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W . L . LErCt~MAm~, H. E. PARKER and P. J. W~sT

reactor. The problems attendant to such storage are not a lack of technology but the provision of facilities and practices to assure continued cooling, adequate monitoring and surveillance to detect release of activity from the containers, adequate treatment of effluents, no unauthorized entry or removal and that faulty or failed containers can be replaced or overpacked. However, if the fuel is to be considered as waste; that is, not to be processed; then one is faced with all the normal high-level waste problems plus the questions of how to handle the gaseous wastes and should the oxide material be converted to another form or can it be overpacked and stored or disposed of, in its present form, with or without outgassing? Furthermore, unless there is a disposal method available for these alpha-bearing wastes, then one is faced with their continuing storage or reprocessing these fuels as a way of disposal.

this may be decided on in individual cases to allow reuse of the site or for aesthetic reasons." Anyone who has dismantled a contaminated hood or glove box, or closely observed such an operation, can begin to appreciate the problems of decommissioning a reactor to Stage 3. But, can anyone really appreciate the problems of decommissioning a plutonium fuel fabrication plant or a fuel reprocessing plant to Stage 3? The costs of such a decommissioning effort, including the management of the resulting wastes, have been estimated to equal or exceed the original facility cost. Although no one has tried to design a facility for ease of decommissioning, the studies and actual decommissioning work done to date indicate that many of the design alternatives that are most attractive from the construction and operations viewpoint may make decommissioning much more difficult. If one objects to passing a nuclear liability to future generations, this decommissioning problem DECOM2VIISSIONING already seems to have got out of hand. But that The decommissioning of facilities associated with does not mean it should continue to be. Governnuclear power generation will not become a wide- ments, regulatory authorities, utilities and industry spread problem for 20 or 30 yr. However, what is need to face the questions--who is going to "clean done each day in designing, constructing, operating up" and "how much" when operations at a nuclear and maintaining these facilities determines the facility cease? If a government is going to do it, magnitude of that problem. A group of consultants criteria need to be established for the condition of for the Agency has defined three stages of decommis- the facility at the time of its transfer for decomsioning as follows: missioning. If a public utility is to do it, the anticipated cost should be taken into account in the Stage 1 : Lock up with surveillance charges for electric power. If industry is going to be "This can generally be regarded as a temporary liable for decommissioning its nuclear facilities, then expedient prior to future work, but in many cases it their charges also must take into account the costs may be all that is justifiable." of decommissioning. At this time, criteria for decommissioning and, arrangements for the funding Stage 2: Conversion and restricted site release to do this is not being taken into account. No mat"This stage can take many forms but means ter who will do the decommissioning, the public essentially that some or all of the plant is converted should insist that total cost be minimized since in to other uses." The level or type of contamination the end the public will pay for it. That means that of the plant and its equipment, along with the criteria for the decommissioned site and facility ability to decontaminate would determine its should be established, then decommissioning plans permissible use. Extensive decontamination, along should be factored into plant design and into operwith equipment replacement, may have to be done ating and maintenance procedures. This planning for its modifications to permit other uses. But, for decommissioning is a drastic departure from eventually there will come an end to the useful life present practice but until it is done, how can the public and those opposed to nuclear power be conof the plant and its facilities. vinced that nuclear monuments are not being built. Stage 3 : Unrestricted site release " F o r thit stage removal of all significantly radioactive equipment and structural material is Krypton-85 and Tritium required to allow unrestricted access and unresIn gaseous radioactive wastes, the nuclide of tricted land use. This does not necessarily mean complete demolition of the non-radioactive struc- concern to date has been iodine-131. However, tures as a part of the decommissioning, although with its 8-day half-life, it is controlled rather simply

Management of radioactive wastes either by sorption in an appropriate media and allowed to decay or by allowing sufficient radiodecay time prior to reprocessing the fuel. Gaseous radionuclides that may become a problem in the future are tritium, krypton-85 and possibly iodine-129. Xenon-133 with its relatively short (5.3 day) half-life is not anticipated to become a problem. On the other hand, there is some concern being expressed regarding a build-up of carbon-14 in the atmosphere and biosphere as a source of population exposure from nuclear power (Martin and ApSimon, 1974). While the capacity of the environment with respect to tritium, krypton-85 and iodine-129 is not well established, it has been estimated that the global concentrations of tritium and krypton-85 may approach acceptable limits during the first half of the next century. Some regulatory groups and critics maintain that the technology which is available today should be applied and recovery of these nuclides be initiated immediately. Apparently, they have been misled by work reported on the pure gases into believing there is such technology ready for application. Tritium acts chemically as hydrogen and readily replaces one atom of hydrogen in water. Therefore, tritium released as a gas may be deposited locally by rainout and tritium released in aqueous effluents also causes local radiation levels somewhat above the global levels of tritium. On the other hand, krypton, being a noble gas, is distributed globally as dictated by meterological conditions. The principal releases of krypton and tritium occur during fuel reprocessing. If it were feasible to trap all tritium (T) in the dry, gaseous state, the retention would not be so difficult. However, much of it is formed or released in aqueous media resulting in a very dilute tritiated water. A number of process survey studies have been undertaken but little experimental effort has been devoted to this problem to date. One proposal to handle the gaseous tritium is to collect all air from the shearing and other reprocessing plant head-end operations, oxidize it, covcrting the T2 to T20 and recover the T20 at a concentration of 1-5 7o. Adsorption of tritium on vanadium oxide is under study as are isotope separation processes such as high pressure and temperature diffusion through palladium films. The use of solvent extraction to separate H20 and H T O has also been suggested. After concentration, the tritium must be stored. Some experimental work is underway on making concrete with tritiated water followed by polymer impregnation of the concrete blocks to reduce leaching; adsorption of H T O on silica gel followed by incorporation in concrete or polymer and the

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reaction of H T O with calcium carbide to produce acetylene which is then polymerized. The bulk of the krypton is released in the head end of the fuel reprocessing plant. Separation processes potentially applicable to removing krypton from off-gas streams include absorption in liquids (liquid air, carbon dioxide, or fluorocarbons), absorption on charcoal and other solids, thermal diffusion, electrostatic diffusion and diffusion through a selective membrane. These processes are at a variety of technological levels and each has its own particular advantage or disadvantage. The cryogenic process is at a high state of development due to its use commercially for non-radioactive noble gas recovery. A cryogenic liquid-air absorption process has been operated intermittently at the Idaho Chemical Processing Plant for many years to recover krypton-85 for a variety of uses, but quantitative recovery has never been attempted. This process has the disadvantage of the potential explosion hazard of ozone. Absorption in fluorocarbons has been piloted only and more work is required on feed pretreatment. Selective membrane work has been performed only on bench scale but it would be a high capital cost process. Also, the effect of radioactivity on membranes operating under high differential pressures is unknown. Actually, the principal technology to resolve in all processes is clean-up and pretreatment of the gas to produce a suitable feed. High pressure confinement in steel cylinders presently appears to be the most practical means of isolating the krypton-85. However, inclusion of the krypton-85 into glasses, resins, molecular sieves and metals offers ways of reducing the effective vapour pressure in a cylinder. Storage or disposal methods that have been considered include placing the cylinders into an engineered storage facility, dumping the cylinders into the sea, and direct discharge of the krypton-85 into an appropriate geologic formation. The foregoing attempts to summarize the state of technology for removal and concentration of tritium and krypton-85. One cannot say that their removal from gaseous waste is an immediate waste management requirement but it may become one in the future. Consequently, within the next ten years processes for removal and confinement of these two gaseous radioisotopes should have been demonstrated and available. To do this, it seems that there is going to have to be a greater level of effort in developing the appropriate technology than there exists at present. In addition to developing technology for handling tritium and kryptoii-85, the

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waste management ramifications regarding carbon14 also should be investigated. STORAGE AND DISPOSAL OF HIGH-LEVEL AND ALPHA-BEARING WASTES Satisfactory technology is either being used on a routine operating basis or being demonstrated for every sector of the nuclear fuel cycle except for high-level waste disposal which is disposal in the sense that the hazardous concentrations of radionuclides are effectively isolated from the biosphere in a final resting place where control and surveillance eventually can be relinquished. After over 20 yr of nuclear power programmes in several of the major developed countries, technology for the solidification and storage of high-level wastes from reprocessing power reactor fuels still remains to be demonstrated on a continuing full scale operating basis, while methods for the disposal of high-level and alpha-contaminated wastes have progressed no further than studies. Although use of several possible alternatives can be projected broadly, reactor operators and authorities responsible for a nuclear power programme do not have adequate knowledge today of what the responsibilities and charges will be with respect to the reprocessing of the fuel and the disposal of the resultant radioactive wastes. The initial concern regarding radioactive wastes from fuel reprocessing revolved about the primary fission product waste stream, a high-level waste, which was thought to constitute a hazard for up to a thousand years. It later was recognized that material contaminated with plutonium and other transuranic alpha-emitting radionuclides could have hazardous periods exceeding a half-million years. However, fission product waste streams and most other high-level wastes contain small concentrations of the alpha-emitting radionuclides, which places them in the alpha-waste category as a long-term hazard. Consequently, the considerations for storage and disposal of the alpha-bearing wastes and the high-level wastes are not too different except that one does not have to be concerned about the high radiation fields and heat dissipation with such alpha-bearing waste containing very little or no fission products. Because of the extremely long half-life of the alpha-emitters and the realization that effective containment has to exist for hundreds of thousands of years, elimination of the alpha-emitters from the bulk of the waste, especially the high-level waste, is an attractive idea. The success of this scheme, removal of the alpha-emitters, would depend upon essentially a quantitative removal of these nuclides from the fission and activation products found in

the reprocessing plant waste stream. Processes are available to achieve a reasonably complete separation of the alpha-emitters from the fission products but the problems are the cost and maintaining the operational controls necessary to achieve such a separation in practice. Then, of course, there is a proliferation of additional radioactive waste effluents and contaminated facilities and equipment which have to be handled and which could be a bigger problem than the original alpha contamination. If separation of the alpha-emitters can be made applicable for a production operation, one faces such questions as are the benefits of having an alpha-free fission product waste worth the cost plus the risks of extra handling and processing and the additional contaminated materials that are generated and what is to be done with the alpha-emitters ? The radioactive waste disposal question is a challenging one and the sooner an acceptable disposal method for these wastes can be demonstrated the better. Until this question is resolved satisfactorily, nuclear power programmes can expect increasing opposition, particularly for the construction of fuel reprocessing plants as well as for nuclear power itself. Opponents of nuclear power are becoming aware that nuclear power reactors in themselves release relatively small amounts of radioactivity when compared with fuel reprocessing plants where the fuels are dissolved with the release of the volatile fission products along with controlled small releases of radioactivity with liquid and solid waste effluents. However, with the exception of the volatiles, essentially all of the nuclear wastes pass through plant process streams and are accumulated in storage areas. The construction of facilities which are to be used for storing the radioactive waste forms during some unspecified interim period while alternative methods for the disposal of their contents are being studied and developed, does not encourage the public confidence regarding the benefits of nuclear power and does provide arguments for those opposed to nuclear power. It is understandable that few, if any, localities feel inclined to accept fuel reprocessing plants and]or waste storage sites with the prospect of becoming what is popularly called "a dumping ground for nuclear waste" regardless of all technological assurances for safe storage of such material. However, localities would, we authors believe, be more ready to accept suitably located fuel reprocessing facilities provided there is an acceptable disposal method being demonstrated. At present, there appear to be four general concepts for the ultimate storage location or disposal of

Management of radioactive wastes those radioactive wastes which require many centuries of isolation, namely : 1. Byextraterrestrial, that is, by disposal into space. 2. By transmutation, for example, by bombardment with atomic particles into stable elements or short half-life radioisotopes. 3. Using the surface ofthe earth, which includes the concepts of using engineered facilities on ground surface or placement on the ocean floor. 4. Using geologic formations on land or beneath the sea bed. While the foregoing concepts have all been studied conceptually, the only promising ones available for application during this century appear to be the last two, using the surface of the earth or geologic formations. If one applies the criterion of retrievability, which could be needed in case of an unforeseen development, then this virtually eliminates the oceans and leaves but two alternatives, land with use of engineered surface facilities or use of geologic formations within land masses. At this time then, one can consider two approaches as being currently applicable for isolating waste from the biosphere for long periods of time: a surface storage facility with continuous monitoring and surveillance versus a disposal technique that presumably would leave no burden to future generations. While one must admit there can be no absolute guarantee of radionuclides not escaping from a geologic site, one also has to consider that there can be no absolute guarantee on the continuous maintenance and monitoring of a surface storage facility. Maybe it boils down to whom one trusts the most, man or nature. In any comparative hazards evaluation between surface and geologic storage one cannot overlook the fact that waste stored or disposed of in a geologic formation, say at least several hundred meters deep, is far better protected from catastrophic acts of nature and man, including the human tendencies for procrastination and neglect, than waste being stored in facilities on the surface of the ground. So, storage in geologic formations might be considered as the best compromise between safety and responsibility. And here, the term storage in geologic formations is used because until the safety of using a geologic location for the disposal of radioactive waste has been reasonably assured, the waste first will have to be stored there. Surveillance and retrievability are relative things. While surveillance and retrievability would be less complicated using a surface storage facility, surveillance and retrievability from a geologic storage site could be accom-

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plished quite readily with proper design and management. The only credible pathway by which radionuclides confined in a geologic formation can reach the biosphere and become a hazard to man are their movement through ground water action. Consequently, the principal criterion for geologic disposal is to use either a dry formation or one where there is little or no movement of ground water with geologic indications that this condition will remain relatively stable for hundreds of thousands of years. Another approach might be to protect the waste and/or radionuclides in it from ground water movement and for redundancy--both measures might be taken. Besides the natural barriers afforded by a geologic disposal site to the movement of radionuclides, the form of the waste and its packaging or containment are two other important aspects which can provide additional elements of safety and confinement for placing waste in a geologic formation. Combinations of the three can provide considerable latitude for assuring perpetual isolation of the radionuclides from the biosphere. Geologic formations such as salt, granites, shales and clays have been in existence and relatively stable for millions or hundreds of millions of years. By thorough investigation of formations and their surrounding formations, the historical stability of the formation can be determined as well as the presence, absence of, or type of, connate or nearby water that might form a pathway to the biosphere and man. Regardless of whether the geologic formations are salt desposits, limestones, shales, granites, etc. most of the locations and deposits probably will be unique and will have to be examined and evaluated as to their respective structure and the particular hydrological situation. Some formations and their situation may be considered "less safe" than others but that does not necessarily mean they would be "unacceptable." All evidence indicates that high-level and alphabearing wastes have been managed safely to date but the questions that nag the public and cannot be answered with evidence today are "What are you eventually going to do with it?." " H o w are you going to isolate it from the environment for the thousands or millions of years that a potential hazard exists ?." " H o w can you be sure it will not contaminate the biosphere?." "What assurance do we have that you can dispose of it safely?." "Where ?," and so on. Therefore, it is imperative that the necessary investigations move ahead to select potential disposal sites in geologic formations and embark upon demonstration projects at these sites

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without further delay. The technology is available to drill holes, construct cavaties, evaluate rock, perform the necessary geologic and hydrological investigations to determine the acceptability of a given geological formation and construct underground engineered facilities to the extent necessary. The technical questions to be resolved are the very long-term stability of waste forms and packaging in its surroundings, interactions between waste forms and the geologic formation and the long-term effects of heat flux and possibly radiation on the geologic structures. Since storage contemplates retrieval; the requirements or proof of long-term suitability of a geologic formation would be less critical for storage than for disposal. As mentioned earlier, any demonstration of disposal in a given geologic formation should be conducted initially as a storage operation. When the safety of the site and the operation has been demonstrated and proven beyond reasonable doubt, the intent to retrieve can be abandoned, the degree of surveillance reduced and the operation continued as disposal. In general, resolution of the high-level and alphabearing waste disposal question seems to be one of the most serious problems and highest priority objectives facing the nuclear industry today. The construction and maintenance of interim surface storage facilities does not provide the final answer and may not reassure the public. Technology is available today to demonstrate and prove that certain geologic locations are acceptable for waste storage, hopefully leading to disposal. One might question if funds and resources used for constructing and maintaining surface storage facilities could be devoted better during the next ten years to evaluating and demonstrating geologic storage with disposal in mind. Nuclear power is in trouble now because there has been no demonstrated approach or real life resolution of the long-term radioactive waste disposal problem. Critics of nuclear power are using this point more and more effectively. One can expect public and political groups, particularly where fuel reprocessing plants are proposed, to listen seriously to these critical views. Once nuclear wastes are being stored in an acceptable geologic formation in a retrievable manner, demonstrating long-term applicability, and the method can be logically explained and defended in public forums, nuclear power and especially fuel reprocessing plants should become more acceptable. Some suggestions along these lines will be made later.

REGIONAL FUEL REPROCESSING AND WASTE MANAGEMENT CENTRES This past October 1974, the Agency's staff made a cursory study to estimate the economic benefits which might result from regional centres for nuclear fuel reprocessing. What might be considered more or less a typical region was studied using a projected fuel reprocessing load of the region for the year 1990. The following three fuel reprocessing and waste management strategies were examined briefly to determine their comparative costs. I. One fuel reprocessing facility for the region. II. Two fuel reprocessing facilities for the region. III. Local fuel reprocessing facility for each country. Capital and operating costs for the various reprocessing and waste management capacities that would be required were estimated and totalled for each strategy, and compared. It was assumed that each fuel reprocessing plant buried its low-level solid waste and stored its solid alpha-contaminated and high-level solidified wastes in surface storage facilities pending the availability of facilities for the ultimate disposition of such wastes. An allowance was made for the impact of fuel transport casks and transportation charges if the fuel was not reprocessed locally. In addition, a comparison was included of storing the irradiated nuclear fuel at centralized facilities. To establish a common basis for a cost comparison, it was assumed that both waste and fuel storage facilities would be constructed with storage capability for 20yrs of operation at the estimated 1990 fuel discharge rates of the region and all facilities were amortized over the 20 yr operating period. Assuming a cost index of one (1.0) for the estimated capital investment and, similarly, a cost index of one (1.0) for the estimated operating cost of the regional plant, the following tabulation presents the comparisons which were found for the region that was studied. Cost index comparison of fuel management alternatives* Capital Operating investment costs Fuel Reprocessing Strategies:t A regional facility Two regional facilities Local facilities Fuel storage strategy

1.0 1.1 1.5 0.6

1.0 I. 1 1.6 0.3

* Capital investment and operating cost indices are not additive. t Includes waste management through solid waste storage.

Management of radioactive wastes 8

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capacity

Fig. 2. Index of fuel reprocessing-waste management costs* for tributary nuclear generating capacity. While the study did include the alternatives of regional and local fuel storage centres, there appeared to be no significant economic difference between them because of the cost impact of fuel transport. The study also considered locating the two regional fuel reprocessing centres so as to maximize their size as opposed to locating them to minimize spent fuel transportation. Here again no significant economic difference was noticed for the region. It should be emphasized that the indices do not indicate the potential economic benefits to any individual country but only for the region which comprised the countries. However, the studies did show the impact of fuel reprocessing and the management of the generated radioactive wastes on a nuclear power programme. Figure 2 indicates that part of the nuclear power generation costs, which include those costs generally associated with captial recovery, operations and maintenance, nuclear fuel and the nuclear fuel cycle, that can be attributable to fuel reprocessing and management of the radioactive wastes. The waste management costs include solid waste burial, which are relatively insignificant, and high-level waste solidification and interim Storage of the solid high-level and alpha-bearing wastes. * Waste m a n a g e m e n t costs are through solid waste storage.

Both the cost index tabulation and Fig. 2 show there are significant economic incentives for countries with smaller nuclear power programmes to co-operate in considering regional centres for fuel reprocessing and handling the radioactive waste therefrom. For example, Fig. 2 indicates that, exclusive of transport costs, it would cost a national power programme of 40,000MWe generating capacity around 1.2 times more annually and one of 10,000 MWe generating capacity around 2.3 times more annually for local reprocessing than to use a regional centre serving a tributary nuclear generating capacity in excess of 80,000 MWe. Also from Fig. 2, it appears that the waste management costs will comprise from 33 to 40% of the total fuel reprocessing--waste management costs or range from about a half up to two-thirds of the fuel reprocessing costs. As previously qualified, the waste management costs included solid waste burial, high-level waste solidification and high-level and alpha-bearing solid waste storage in surface facilities, but not waste disposal. Besides any economic advantages, there are at least two other good reasons, from a waste management standpoint, for international co-operation in using regional centres for nuclear fuel reprocessing and handling the radioactive wastes. One reason is to reduce the number of sources of radioactive contamination and the number of facilities contaminated

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with radioactivity. This would be particularly significant thirty to fifty or more years from now when many nuclear facilities constructed today will have served their useful lives and must be decommissioned to a safe condition. Another reason is that well-located, well-managed, well-staffed, well-operated regional centres should significantly reduce the risk of an accidental large release of radionuclides into the environment or of causing a major radiation exposure to a population group. Such a release or an exposure probably would cause a world-wide adverse public reaction, possibly to the extent of disrupting large nuclear power programmes in developed nations as well as having an adverse impact in developing countries. Consequently, it would appear to be in the best interest of those nations well advanced in nuclear power generation and nuclear technology to provide all possible co-operation and encouragement in the development of suitably located regional fuel reprocessing and waste management centres in order to minimize the number of smaller fuel reprocessing centres and radioactively contaminated sites and also to avoid the possibility that some of them may be inadequately equipped or operated with respect to the safe handling of radioactive materials, especially wastes. As was recently pointed out by a group of Senior Advisors convened by the Agency to review radioactive waste management technology, " . . . it is not possible to separate considerations of spent fuel processing from waste management acitivities. The availability of an adequate and proven system for ultimate disposal of radioactive wastes will be an important element in the decisions concerning the installation of regional reprocessing centres." And one might add, this applies to the construction of any fuel reprocessing facility--no matter where it is located. Consequently, this suggests that there should be a concentrated co-operative effort among those countries having or considering nuclear power to resolve the question of high-level and alpha waste disposal as quickly as possible. This is not a small task. One or two countries cannot do it all. Both its urgency and the resources required call for international co-operation. The effort should be concerned with various countries exploring, determining the acceptability of, and, where favourable, demonstrating the use of geologic locations within their boundaries for the emplacement of radioactive wastes. Acceptable geologic formations need not necessarily be limited to salt deposits but may include such formations as granites, bedrock, shales, limestones, etc., if located in a suitable geologic environment. Furthermore,

because of its geologic environment, a given type of formation may appear suitable for waste disposal in one country but not in another country. There should be a co-ordinated exchange of information as such an international programme progresses. One approach would be the establishment of an international group of geologists, hydrologists, waste management experts, scientists and mining engineers and, yes, even environmentalists. (After all aren't most of us environmentalists despite any allegations to the contrary.) Such a group could provide co-ordination and advice for the task. Regardless of the approach for coordination, there should be developed in the international technical community the basis for a consensus, that, under reasonable conditions, storage, leading to disposal, of radioactive waste in certain geologic formations in suitable geological environments is acceptable. MATURITY OF NUCLEAR ENERGY The theme for this First European Nuclear Conference is the Maturity of Nuclear Energy. Maturity should not necessarily mean that the best possible technology has been developed and is being applied but that existing technology can be successfully applied where it is needed. In this respect, one can say that radioactive waste management is one off-spring of nuclar energy which, while well on the road, has not reached maturity. What is there yet to be done? Hopefully, it is clear what we, the authors, think should be done but to make our points again, briefly: (a) There should be better management of and control over mill tailings. Here, it probably requires more conscientious application of existing technology. (b) While not necessarily waste disposal, fuel storage should be recognized as a viable alternative to reprocessing, at least for the next ten years or so. There should be incorporated in the planning and construction of nuclear reactors the capability for storing, say five years of fuel discharges, with the means for easy expansion. An alternative could be the construction of storage basins servicing a number of reactors. Adequate fuel storage technology exists and is being used. (c) There should be a recognition of the decommissioning (and decontamination) of nuclear facilities and equipment in their design. Regulatory bodies should establish criteria for decommissioning and a decommissioned site so the criteria can be taken into account during the planning and design stages for a nuclear facility.

Management of radioactive wastes (d) Technology should be developed and demonstrated within the next ten years for removal, concentration and containment of krypton and tritium from fuel reprocessing effluents in order to have such technology available if and when it is required. The carbon-14 question should be investigated. (e) Demonstrating the disposition of the high-level and alpha-bearing wastes in suitable geologic formations should proceed without delay. Adequate technology appears to exist for locating appropriate sites and demonstrating waste storage there, leading ultimately to disposal. Resolving the disposal question appears to be the most crucial challenge for waste management technology today, and, possibly, the acceptance of nuclear power. (f) In a way, with the exception of mill railings and fuel storage, the other areas of difficulty in radioactive waste management which have been mentioned could be reduced by regional fuel reprocessing and waste management centres rather than having a proliferation of local facilities. It should help to

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minimize the potential hazards associated with fuel reprocessing and the subsequent handling of the radioactive wastes. There should be a conscientious effort to resolve any national and international barriers to regional sites. In spite of civil and public impediments, nuclear reactors are going to continue to be built and operated and spent nuclear fuels will be discharged in increasing quantities. What is to be done with them and their radioactive wastes? A criterion of maturity is reasonable co-operation. For nations to achieve nuclear maturity, there must be a co-operative effort amongst them to manage nuclear energy wisely and safely and join together in minimizing the impact of the disadvantages such as the radioactive wastes, that arise from its use. REFERENCES Martin A. and ApSimon H. (1974) Population Dose _ Evaluation and StandardsJbr Man and His Environment, pp. 15-26. IAEA, Vienna, STI/PUB/375.