RADIOACTIVE WASTE DISPOSAL

Transcription

1 7. RADIOACTIVE WASTE DISPOSAL There are two basic strategies for radioactive waste disposal: isolate and confine or dilute and disperse. The first strategy involves the emplacement of waste into a disposal facility that is intended to isolate the waste from humans and the environment and to prevent or limit releases of potentially harmful substances (toxic metals, radionuclides, organics) such that human health and the environment are protected. The second strategy involves deliberately dispersing the waste into the environment in a manner intended to dilute harmful contaminants in the waste to levels that are considered acceptable according to internationally agreed standards [3.3]. Both of these strategies can include provisions for the decay of radionuclides before they are released into the environment. For example, radionuclides with very short half lives (days or months) can be stored until they are decayed and then the waste can be disposed in a nonradioactive landfill or directly discharged to the environment. In the case of radionuclides with half lives of years to tens of years, disposal facilities can be designed to isolate the waste for the time necessary for radionuclides to decay to insignificant levels. LILW Disposal The disposal method for LILW (see Section 3, The Classification of Radioactive Waste ) depends upon whether or not the waste is short-lived (LILW-SL) or long-lived (LILW-LL). For LILW-SL, a common strategy is to confine the wastes for a time frame sufficient for the radionuclides to decay to insignificant levels (generally a few hundred years). For LILW-LL, much longer confinement times are required. In addition, there is an expectation that some radionuclides in the waste will not decay to insignificant levels before there is any significant degradation of the contents of the disposal facility or of the facility itself. In this case, a defence-in-depth strategy is used, which relies on multiple barriers, both engineered and natural, to ensure that in case of any releases only acceptable quantities of materials are released into the environment in any given time period. The three major options for LILW disposal currently used or planned by IAEA Member States are: surface / near surface facilities, rock cavities (at several tens of meters to a few hundreds meters depth), and deep geologic repositories (typically at depths of more than a few hundred meters). A few conclusions can be drawn for LILW-SL management: surface / near surface disposal is and will most likely continue to be the most common disposal practice, and for various reasons, such as geological, climatic and socio-economic conditions or to minimize the risk of inadvertent intrusion into a disposal facility, some Member States have opted to dispose of their LILW-SL in rock cavities or geologic repositories. It is evident that the technical approaches and concepts also reflect the specific regulatory requirements, status of technical developments and capabilities at the time the repositories were licensed, built and operated. For example, simple shallow land trench concepts have Page 66 of 127

2 been adopted at Barnwell in the USA and at Vaalputs in South Africa since these sites have a low population density and a thick surface soil layer of low permeability. At the Centre de l'aube in France, Rokkasho in Japan, Drigg in the United Kingdom, and El Cabril in Spain, engineered concrete vault, near surface repositories have been designed and built to minimize groundwater infiltration into the repository, to decrease the potential release of radionuclides from the repository into the environment and to deter intentional or inadvertent human intrusion into the repository. In other countries, repositories in hard rock caverns are in operation, such as those at Forsmark in Sweden, Himdalen in Norway and Olkiluoto in Finland. Table 7-I, from the report Radioactive Waste Management Profiles - Compilation of Data from the Waste Management Database, No. 3 [2.6], indicates: an increase in the percentage of Member States reporting that LILW-SL are or will be disposed of in surface or near surface repositories (based on a decrease in the percentage of Member States that had not specified a disposal option), a shift in the percentages of Member States reporting that LILW-SL are or will be disposed of in rock cavities (at depths of several tens of meters to hundreds of meters) or in a geologic repository, an increase in the percentage of Member States reporting operating disposal facilities for accepting LILW-SL (based on a decrease in the percentage of Member States that had not specified a disposal facility operating status), essentially the same percentage of Member States reporting that they do not have an operating disposal facility for LILW-SL - however there was a decrease in the number of planned facilities and an increase in the number of facilities under construction, and an increase in the number of closed/shut down disposal facilities (in Brazil, Bulgaria, Estonia and France). Table 7-I: The Status of LILW-SL Disposal in IAEA Member States Number of Number of Countries per Type of Disposal Number of Countries versus Disposal Facilities Waste Countries surface or rock geologic not Class Reporting near surface cavity repository unspecified operational operational unspecified LILW-SL fraction => LILW-SL fraction => breakdown of "not operational" facilities Planned Under Construction Shut Down or Closed Some Member States reported more than one type of disposal facility - in some cases, not all had the same status The table above does not include the Russian Federation. The WMDB uses reference year 1993 for data collected in response to the 1991/92 Questionnaire and it uses reference year 1997 for data collected in response to the 1997/98 Questionnaire. Long-lived radionuclides can be found in varying concentrations in LILW arisings from uranium conversion and enrichment, nuclear fuel fabrication, the operation of nuclear power plants and the decommissioning of nuclear fuel cycle facilities. In accordance with the proposed IAEA waste classification scheme, LILW-LL is not considered to be suitable for disposal in near surface disposal facilities because of its higher concentrations of long-lived radionuclides. It is considered for deep geological disposal only. Page 67 of 127

3 Uranium isotopes and, in the case of mixed oxide (MOX) fuel, plutonium isotopes are found in solid and liquid wastes from uranium conversion and enrichment. Wastes from nuclear power plant operations include additional long-lived radionuclides such as C-14, Ni-59, Tc-99, I-129 and actinides. Ni-63 and Ni-59 can be found, for example, in activated metals and actinides can be found in wastes associated with the primary coolant water if there is some defective fuel. Radionuclides such as Ni-59, Ni-63, C-14 and isotopes of Europium can also be a concern in decommissioning wastes. Measures are being taken to reduce the amount of long-lived radionuclides in activated metals and in concrete by using structural materials that have a low nickel or Europium content [3.7]. Europium isotopes can also be a waste management issue for concrete shielding used at accelerator and research reactor installations. When addressing the long-term isolation of LILW-LL, the concentrations in water around the waste, and thus, potential releases of long-lived radionuclides can be significantly reduced by including features to take advantage of the chemical properties of specific radionuclides [7.1] to [7.3]. However, it is recognized that a carefully selected host rock formation with a sufficiently low groundwater flow is a major condition for the safety performance of the repository. Technology development has focused on waste packages, buffer materials and barriers with characteristics that create a long-term chemical environment where specific radionuclides can be sorbed on the packaging materials, buffer or barrier or can precipitate into a solid phase. Technologies involving cement are particularly effective against releases of C-14 [7.4]. For example, after the concrete begins to fail as a physical barrier (several hundred years), releases of C-14 are still limited by the chemical properties of concrete. This results from the precipitation of dissolved carbon at high ph conditions caused by degrading concrete. For wastes containing Tc-99, waste forms and buffer materials have been formulated to create a long term reducing environment, because technetium has a very low solubility in reducing conditions and thus concentrations of Tc-99 in water would be solubility limited. Table 7-II from the Profiles report [2.6] indicates: an increase in operations or plans for LILW-LL disposal in rock caverns or geological repositories, and a higher uncertainty for LILW-LL disposal than for LILW-SL disposal (about half of the Member States did not specify a disposal option for LILW-LL). Table 7-II: The Status of LILW-LL Disposal in IAEA Member States Number of Number of Countries per Type of Disposal Number of Countries versus Disposal Facilities Waste Countries surface or rock geologic not Class Reporting near surface cavity repository unspecified operational operational unspecified LILW-LL fraction => LILW-LL fraction => breakdown of "not operational" facilities Planned Under Construction Shut Down or Closed Some Member States reported more than one type of disposal facility - in some cases, not all had the same status The table above does not include the Russian Federation. The WMDB uses reference year 1993 for data collected in response to the 1991/92 Questionnaire and it uses reference year 1997 for data collected in response to the 1997/98 Questionnaire. Page 68 of 127

4 HLW/SF Disposal Most countries with nuclear power programmes also have programmes underway to develop the technology for the management of HLW and/or spent nuclear fuel (SF) and to construct/operate repositories for their disposal. Countries have two principal options (also see Section 3.3, Spent Nuclear Fuel: Waste or Resource? ): SF can be reprocessed to recover plutonium and uranium for recycling and the resulting liquid HLW can be conditioned (vitrified, for example) and eventually emplaced into a repository, or SF can be declared as waste and, after a suitable period of storage for radioactive decay, can be disposed of in a similar manner to vitrified HLW disposal (direct disposal). Regardless of the chosen option, many Member States plan to dispose of HLW or SF in geological repositories that have a system of engineered and natural barriers to isolate the waste from humans and the environment. It should be noted that special considerations may be required for SF from research reactors, which have fuels with different characteristics and burnup histories than fuel from nuclear power plants [7.5]. It should also be noted that changes in reprocessing strategies may influence the direct disposal alternative [7.6]. Although strategies may differ between national HLW/SF management programmes, the approach and methodologies used by Member States are often quite similar, thereby creating a sound basis for information exchange and other co-operative activities. For example, most national programmes call for geologic disposal of HLW and/or SF and a for national effort to implement such programmes (see Table 7-III). Some programmes have identified sites, while others are in the process of preparing programme strategies and approaches. Many Member States with a HLW/SF disposal programme are heading in a similar direction and are faced with similar challenges and issues. Table 7-III, from the Profiles report [2.6], indicates: no significant change was reported by Member States for plans for HLW or SF disposal, and about half of the Member States did not specify a disposal option for HLW or SF in response to the last WMDB questionnaire. some Member States have sent or have plans to send some or all of their SF to its country of origin (small quantities of SF from research reactors), some Member States have sent or have plans to send some of their SF to other countries for reprocessing and, therefore, have plans or will need to develop plans for disposal of the HLW returned to them from reprocessing plants, no HLW or SF repositories are yet in operation in any Member State; this remains a major challenge in radioactive waste management. Readers of this Status and Trends report are cautioned to consider the information in Table 7- III in combination with a review of individual HLW and SF reports for Member States as they appear in the Profiles report. Page 69 of 127

5 Table 7-III: The Status of HLW and SF Disposal in IAEA Member States Number of Number of Countries per Type of Disposal Number of Countries versus Disposal Facilities Waste Countries surface or rock geologic not Class Reporting near surface cavity repository unspecified operational operational unspecified HLW fraction => HLW fraction => breakdown of "not operational" facilities Planned Under Construction Shut Down or Closed Number of Number of Countries per Type of Disposal Number of Countries versus Disposal Facilities Waste Countries surface or rock geologic not Class Reporting near surface cavity repository unspecified operational operational unspecified SF fraction => SF fraction => breakdown of "not operational" facilities Planned Under Construction Shut Down or Closed UK not included, "SF is not considered to be waste" The WMDB uses reference year 1993 for data collected in response to the 1991/92 Questionnaire and it uses reference year 1997 for data collected in response to the 1997/98 Questionnaire. The development of underground research facilities or laboratories (URL) is an important tool for acquiring the necessary understanding of natural processes, for feasibility demonstrations of a number of technical issues, for providing an adequate level of confidence in models to be used for the various assessments and, for providing a representative database for these assessments. Most of the presently operational and planned URL can be considered as being developed for methodological purposes. The development of an underground research facility or a URL on a potential disposal site has merit as it will contribute considerably toward the characterization of that site. Table 7-IV lists: dedicated underground research facilities or URL, research facilities in existing repositories or in repositories in the licensing process. Page 70 of 127

6 Table 7-IV: Main Underground Research Facilities (information compiled by consultants at an IAEA sponsored meeting in 1999)* COUNTRY LOCATION USUAL NAME/TYPE OF FACILITY TYPE OF RESEARCH Page 71 of 127 HOST ROCK/ FORMATION NATURE OF EXPERIMENTS [3] TIME PERIOD BELGIUM MOL HADES+URF S [1] Plastic clay TCHMR+D since 1980 PRACLAY CANADA LAC DU BONNET URL G [2] Granite TCHM since 1984 Manitoba FINLAND OLKILUOTO Research Tunnel G Granite HM+D since 1993 (in VLJ repository) FRANCE FANAY Galleries in G Granite TCHM Augères/Tenelles U Mines AMELIE Galleries in G Bedded salt TM+D K Mine TOURNEMIRE Test Galleries G Shale CHM since 1990 GERMANY ASSE Test Galleries in G Dome salt TCHM/R + D K/salt mine GORLEBEN URL S Dome salt Characterization in exploration galleries since 1997 (now halted) KONRAD Test Galleries in S Shale CHM since 1980 Fe Mine JAPAN TONO Galleries in G Sandstone CHM since 1986 U Mine KAMAISHI Galleries in Fe-Cu G Granite Characterization Mine SWEDEN STRIPA Galleries in G Granite TCHM Fe Mine ÅSPÖ HRL G Granite TCHM + D since 1990 SWITZERLAND GRIMSEL GTS at dam G Granite TCHM since 1983 tunnel MONT TERRI Galleries at road G Shale TCHM since 1995 tunnel USA NEVADA Test Site CLIMAX G Granite D NEVADA Test Site G-Tunnel G Tuffs THM CARLSBAD WIPP S Bedded salt TCHM/R+D since 1982 YUCCA Mtn. ESF S Tuffs TCHM+D since 1993 YUCCA Mtn. Busted Butte G Tuffs CHM since 1997 * Existing facilities where tests were and/or are still undertaken. 1 (S) = Site-specific 2 (G) = Generic 3 T - Thermal, C - Chemical, H - Hydrogeological, M - Mechanical Tests, R - Radiation tests, D - Demonstration tests For information on salt formations, see Characterization of Bedded Salt for Storage Caverns, Recent Hydrogeological Research Published by the Bureau of Economic Geology, TRU Disposal Some Member States consider Transuranic (TRU) waste, also often referred to as alpha waste, to be a component of LILW-LL and, therefore, report TRU management as part of LILW-LL management. Some Member States manage LILW-SL and LILW-LL together as LILW and report LILW-LL and TRU management as part of overall LILW management. As such, the assessment of the world-wide management of TRU is difficult. Table 7-V from the Profiles report [2.6] indicates: essentially the same number of Member States reported TRU management separately in response to two WMDB questionnaires (however, different countries reported), and two Member States began operating repositories that can accept alpha bearing waste since the Radioactive Waste Management Profiles No. 2 was issued. Repositories in Norway (Himdalen) [7.7] and the United States of America

7 (Waste Isolation Pilot Plant, WIPP) [7.8] began operation in At time of writing, alpha bearing waste had not yet been disposed of in the Himdalen facility, whereas the WIPP facility has begun to accept TRU waste. However, the Himdalen facility also has chambers where long-lived waste is stored. Table 7-V: The Status of TRU Disposal in IAEA Member States Number of Number of Countries per Type of Disposal Number of Countries versus Disposal Facilities Waste Countries surface or rock geologic not Class Reporting near surface cavity repository unspecified operational operational unspecified TRU fraction => TRU fraction => breakdown of "not operational" facilities Planned Under Construction Shut Down or Closed The WMDB uses reference year 1993 for data collected in response to the 1991/92 Questionnaire and it uses reference year 1997 for data collected in response to the 1997/98 Questionnaire. 7.1 Topical Issue: Retrievability or Long-Term Storage versus Disposal The concept of retrievable disposal has attracted wide attention in recent years, such as Session 36, Monitoring and Retrievability Issues in Deep Disposal at the Waste Management 01 Symposium in Tucson, Arizona, USA, in February Originally the approach of deep geological disposal was developed to remove waste from the human environment to ensure that it remains isolated from that environment and inaccessible to humans for the very long time scales corresponding to the slow decay of long-lived radionuclides. The concept utilizes multiple barriers, such as the waste form, container(s), overpack(s), sealant(s), backfill, buffer(s), and the geosphere. The IAEA defines a disposal as [5.1] The emplacement of waste in an approved, specified facility without the intention of retrieval In many cases, the only element of this definition that is important is the distinction between disposal (with no intent to retrieve) and storage (with intent to retrieve) If retrieval of the waste at any time in the future is intended, the term storage is used The term disposal implies that retrieval is not intended; it does not mean that retrieval is not possible. Retrievability is the theoretical ability to recover wastes from a repository, regardless of how difficult that may ultimately prove to perform. Retrieval is the actual act of waste recovery from a repository. Organizations responsible for implementing repositories tend to refer to retrievability as an unlikely and probably unnecessary option. On the other hand, the public tends to express concern about how retrieval could actually be performed. The issue of retrievability centres on: storage (intent to retrieve) versus disposal (no intent to retrieve) disposal, including the accessibility of waste for retrieval, and the impact of accessibility on waste isolation and containment. Retrievability is viewed as a confidence builder by some since it does not leave the legacy of a final option for future generations. However, others feel that retrievability reduces confidence in the robustness of a repository since it could provide a pathway either for the Page 72 of 127

8 release of radionuclides and other hazardous materials from the repository or for gaining access to a repository, which is a safeguards concern. A variety of terms have been suggested to distinguish a repository without retrievability features from one with retrievability features, such as Very Long-term Interim Storage, Reversible Geological Storage, and Monitored Geologic Repository. In one concept, retrieval would not be taken to mean re-mining the disposed waste from a closed and sealed repository. Instead, the waste would be accessible for a certain period after waste emplacement to ensure that it could be readily removed [7.9]. Retrievability, currently viewed as the implementation of mechanisms to facilitate waste retrieval, whether or not there is an intent to retrieve, should not be confused with some current or past efforts to remove wastes from disposal facilities that have been deemed to be inadequate by today s standards (such as the retrieval of waste from RADON-type facilities in countries of the former Soviet Union). These past and current remediation activities represent retrieval, whereas the facilities were not originally implemented with retrievability in mind. Discussion regarding retrievability of nuclear wastes tends to focus on deep geological disposal for HLW or spent nuclear fuel. However, several countries propose some form of codisposal of long-lived plutonium-contaminated wastes, often referred to as intermediate-level waste (ILW) or transuranic waste (TRU). Doubt has been expressed about whether or not the characteristics of LILW, for the major part consisting of radionuclides with relatively short half-lives, would qualify it as a material for which the objectives for retrievability have any significance [7.10]. However, in response to public concerns, proposals have been made to implement retrievability with the Assured Isolation Concept (see Section 7.2, Topical Issue: Delays in the Implementation of Disposal Programmes ) for commercial LLW in the United States of America [7.11]. Additional reading material on retrievability can be found in references [7.12] to [7.17]. 7.2 Topical Issue: Delays in the Implementation of Disposal Programmes An article in the Washington Post [7.18] concerning the Yucca Mountain Project [7.19] for spent fuel disposal in the United States of America stated, With storage facilities at some nuclear power plants nearing capacity, supporters of the measure said urgent action is needed to avert a looming crisis. The country's 103 operating nuclear power plants are generating spent fuel at a rate of about 2,000 tons a year, and some are rapidly running out of space to store the material.. Regardless of journalistic rhetoric and the statistics cited, the fact of the matter is that slow progress on the implementation of disposal facilities (see Table 7-I to Table 7-III and Table 7-V on pages 67 to 72) is resulting in a need for more storage capacity and longer storage times for waste (see Table 6-I to Table 6-III on pages 62 to 63). For example, in an annual report to the Congress of the United States of America [7.20], the Department of Energy stated, Over 25 percent of North Carolina generators will run out of existing storage room within the next three years, with some running out within the next year. Concerns about delays in disposal facility implementation and an increasing reliance on storage for longer periods that anticipated a decade ago have lead to the suggestions for alternatives. For example, the Assured Isolation Concept proposes a concept that does not wholly depend on a site s natural characteristics for protection of public health and safety. It relies instead on a well-engineered structure, planned preventative maintenance, continuous Page 73 of 127

9 monitoring, and accessible facilities. In addition, disposal with retrievability is receiving wider attention (see Section 7.1). Increasingly, public concerns and perceptions and costs are influencing national policies on waste management that, in turn, affect progress in disposal programme implementation [7.21]. Notably, there is often public concern over and opposition to the siting of repositories (the not in my back yard (NIMBY) philosophy). One of the consequences of public concerns is that over the past decade, focus has shifted away from purely technical evaluations of waste management options to a consideration of both technical and socio-political issues [7.22] to [7.26]. Uncertainty about the ultimate disposition of waste (with concepts such as permanent disposal, retrievable disposal, monitored retrievable storage, assured isolation, longterm storage, et cetera) has the potential to simply defer today s problem for future societies. Most countries with nuclear programmes are using the deferral approach for spent fuel management, which provides the ability to continuously monitor spent fuel in storage and to retrieve it later for either direct disposal or reprocessing. Today, the worldwide reprocessing capacity is only a fraction of the total spent fuel arising and since no final repository has yet been constructed, there will be an increasing demand for storage [6.5]. In the United States of America, it has been stated [7.27] that, No new full-range low-level radioactive waste disposal facility has been established since the seventies in the United States The result has been a proliferation of temporary "interim" storage sites scattered throughout this nation as a result of the use of nuclear power and medical, industrial, and research applications. Clearly the situation presented by extended temporary storage sites represents a risk to the general public that cannot continue. With deferral, the problem of what to do with today s waste remains unresolved. For example, some storage sites are in operation well beyond their original estimated service times. This has resulted in the degradation of waste packages and the facilities themselves, which may result in releases of radionuclides into the environment [7.28], [7.29]. The consequence may be expensive remediation activities, which divert limited resources from disposal programmes. It is worth noting that the remediation of facilities within currently licensed, radioactive waste management sites may not be reported by countries to international information systems under the categories of contaminated sites, past practices or decommissioning. The remediation of operating facilities is likely to entail many of the same issues, problems and solutions that would be associated with these activity categories. References for Section The Scientific and Regulatory Basis for the Geological Disposal of Radioactive Waste, D. Savage Editor, John Wiley and Sons, New York, Near-Field Assessment of Repositories for Low and Medium Level Radioactive Waste, Nuclear Energy Agency, Paris, France, Chapman, N.A., Flowers, R.H., Near-Field Solubility Constraints on Radionuclide Mobilization and their Influence on Waste Package Design, Phil. Trans. Royal Soc. London, A-319, 83-95, Dayal, R., Near-Field Barriers for Carbon-14 Isolation, Ontario Hydro Technologies Report OHT-A-NBP P, CANDU Owner s Group report COG , Page 74 of 127

10 7.5 Procedures and techniques for the management of experimental fuels from research and test reactors, International Atomic Energy Agency Technical Document IAEA- TECDOC-1080, International Atomic Energy Agency, Vienna, April Status and Trends in spent fuel reprocessing, International Atomic Energy Agency Technical Document IAEA-TECDOC-1103, International Atomic Energy Agency, Vienna, August Anita A. Sörlie and Erling Stranden, "IAEA - WATRP Review of the Norwegian Combined Storage and Disposal Facility for LLW and ILW", Proceedings of the Nordic Society for Radiation Protection, Rekjavik, Iceland, August The Waste Isolation Pilot Plant web site, H. Selling, A Retrievable Concept for an Underground Radioactive Waste Repository in the Netherlands, Waste Management 98 Symposium, Tucson, Arizona, USA, March Richardson, P.J, Development of Retrievability Plans, prepared for: Dr Olof Söderberg, Swedish National Co-ordinator for Nuclear Waste Disposal (M 1996:C), c/o Ministry of Environment, S STOCKHOLM, Sweden, March D.V. LeMone, The Current Status of the Assured Isolation Concept for Low-Level Radioactive Wastes, Waste Management 2000 Symposium, Tucson, Arizona, USA, March J.B. Grupa et. al., Results of the Concerted Action on the Retrievability of Long- Lived Radioactive Waste in Deep Underground Repositories, Waste Management 01 Symposium, Tucson, Arizona, USA, February The Environmental and Ethical Basis of Geological Disposal: a Collective Opinion of the NEA Radioactive Waste Management Committee, Nuclear Energy Agency of OECD, Paris, Ethical aspects of nuclear waste, Some salient points discussed at a seminar on ethical action in the face of uncertainty in Stockholm, Sweden; September 8-9, 1987, SKN Report 29, Strategic Areas in Radioactive Waste Management Nuclear Energy Agency of the OECD, Paris, Confidence in the Long-term Safety of Deep Geological Repositories: its Development and Communication, Nuclear Energy Agency of the OECD, Paris, C. Pescatore, Long-term management of radioactive waste: ethics and the environment. Nuclear Energy Agency of the OECD, Newsletter, Vol. 17, No.1., Paris, House Backs Nuclear Waste Site Bill, Washington Post, Thursday, March 23, Yucca Mountain Project home page, Report to Congress Annual Report on Low-Level Radioactive Waste Management Progress, U.S. Department of Energy, Office of Environmental Management, DOE/EM-0444, July Page 75 of 127

11 7.21 Low-level Radioactive Waste Repositories: An Analysis of Costs, Nuclear Energy Agency, Paris, France, The Environmental and Ethical Basis of Geological Disposal: a Collective Opinion of the NEA Radioactive Waste Management Committee, Nuclear Energy Agency of OECD, Paris, Confidence in the Long-term Safety of Deep Geological Repositories: its Development and Communication, Nuclear Energy Agency of the OECD, Paris, Pescatore, C., Long-term management of radioactive waste: ethics and the environment. Nuclear Energy Agency of the OECD, Newsletter, Vol. 17, No.1., Paris, Ethical aspects of nuclear waste, Some salient points discussed at a seminar on ethical action in the face of uncertainty in Stockholm, Sweden; September 8-9, 1987, SKN Report 29, Communication and Fourth Report from the Commission on The Present Status and Prospects for Radioactive Waste Management in the European Union, European Commission report COM(98)799, Brussels, D.V. LeMone, T.A. Kerr, and L.R. Jacobi Jr., Assured Isolation Facilities: Solving the problem of safely managing low-level radioactive waste, Waste Management 99 Symposium, Tucson, Arizona, USA, March High Level Radioactive Liquid Waste, United States Department of Energy, Hanford Site, U.S. Nuclear Regulatory Commission, "Extended Storage of Low-Level Radioactive Waste: Potential Problem Areas," NUREG/CR-4062 (BNL-NUREG-51841), December Page 76 of 127