APPENDIX L
INTERIM REPORT OF THE COMMITTEE ON SEPARATIONS TECHNOLOGY AND TRANSMUTATION SYSTEMS

May 15, 1992



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Nuclear Wastes: Technologies for Separations and Transmutation APPENDIX L INTERIM REPORT OF THE COMMITTEE ON SEPARATIONS TECHNOLOGY AND TRANSMUTATION SYSTEMS May 15, 1992

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Nuclear Wastes: Technologies for Separations and Transmutation NATIONAL RESEARCH COUNCIL COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES 2101 Constitution Avenue Washington, D.C. 20418 BOARD ON RADIOACTIVE WASTE MANAGEMENT (202) 334-3066 Fax: 334-3077 Office Location: Milton Harris Building Room 456 2001 Wisconsin Avenue, N.W. 20007 May 15, 1992 The Honorable Leo P. Duffy Assistant Secretary for Environmental Restoration and Waste Management U.S. Department of Energy 1000 Independence Avenue, S.W. EM-1, Room 7A-049 Washington, D.C. 20585 Dear Mr. Duffy: Enclosed is an interim report of the Panel on Separations Technology and Transmutation Systems. The enclosure response to the Secretary of Energy's request for a report on the Argonne National Laboratory and General Electric Company waste management work, as part of the larger study on how the technologies of separation and transmutation might affect the national program for handling high level radioactive waste. If you have any questions, we will be please to meet with you and your staff. Sincerely yours, Norman C. Rasmussen Chairperson Separations Technology and Transmutation Systems Panel The National Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering to serve government and other organizations

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Nuclear Wastes: Technologies for Separations and Transmutation Interim Report of the Panel on Separations Technology and Transmutation Systems Board on Radioactive Waste Management Commission on Geosciences, Environment, and Resources Energy Engineering Board Commission on Engineering and Technical Systems Board on Chemical Sciences and Technology Commission on Physical Sciences, Mathematics and Applications May 1992 National Research Council Washington D.C.

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Nuclear Wastes: Technologies for Separations and Transmutation NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the panel responsible for the report were chosen for their special competencies and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Frank Press is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the national Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Samuel O. Thier is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council. Support for the project was provided by the United States Department of Energy. Copies of this report are available from Board on Radioactive Waste Management National Research Council 2101 Constitution Avenue, N.W. Washington, D.C. 20418 Printed in the United States of America

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Nuclear Wastes: Technologies for Separations and Transmutation Contents Page     Foreword   iv     The Advanced Liquid Metal Reactor (ALMR) as an Actinide Burner   1     Is a breeder program, viable on its own merits, a prerequisite to an actinide burning ALMR program?   1     What could be achieved by actinide burning and on what time scale?   1     What would be the effect on the radiation-induced health risks?   2     What licensing or regulatory problems may be encountered?   4     How would actinide burning affect the need and schedule for the first geological repository?   4     What are the costs of actinide burning?   6     Summary   6     References   7     Panel on Separations Technology and Transmutation Systems   8     Subpanel on Separation   9     Subpanel on Transmutation   10     Subpanel on Integration   11

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Nuclear Wastes: Technologies for Separations and Transmutation Foreword At the Department of Energy's request, the National Research Council of the National Academy of Sciences and the National Academy of Engineering has undertaken a study of how the technologies of separation and transmutation might affect the national program for handling high level radioactive waste. To conduct this study, the National Research Council formed the Panel on Separations Technology and Transmutation Systems (STATS) in the fall of 1991, with instructions to issue a final report by July of 1994. The STATS Panel in its first six months of operation has held a two-day international symposium and has had briefings from the Department of Energy, the Nuclear Regulatory Commission, the Environmental Protection Agency, the General Electric Company, the Electric Power Research Institute, Argonne National Laboratory, Los Alamos National Laboratory, Brookhaven National Laboratory, Hanford Engineering Development Laboratory, and the Yucca Mountain Project. In addition, members of the Panel have made visits to Argonne National Laboratory-East, Argonne National Laboratory-West, Los Alamos National Laboratory, Savannah River, Hanford, and THORP (in the U.K.). This fact-finding effort provided the Panel a large amount of information, not all of it consistent, about these technologies. The STATS Panel is now about to embark on the analysis phase in which we shall draw conclusions about the role separation and transmutation might have in the national high-level radioactive waste program. Some months ago the Department of Energy asked the Panel for a report at about this time, on any insights we might have gained about the General Electric Company-Argonne National Laboratory concept of actinide burning (fissioning) using fast reactors. It would be inappropriate for us to state conclusions about technologies that we have just begun to study. We can, however, review some of the possible results of actinide burning if the system works as well as the proponents have contended it will. This report should not be considered complete in the sense that all important features have been considered. For example, we need to go into greater detail on mass balances; we must address costs and schedules; defense wastes are only touched upon in passing; accelerator transmutation is not addressed - nor is transmutation in reactors other than the ALMR; foreign programs are not addressed herein; and the important topics of impact on proliferation and other institutional issues are not addressed at all. These issues will be considered in the final report.

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Nuclear Wastes: Technologies for Separations and Transmutation The Advanced Liquid Metal Reactor (ALMR) as an Actinide Burner The Advanced Liquid Metal Reactor (ALMR) concept is being proposed by its designers, the General Electric Company and Argonne National Laboratory, as a fast breeder reactor to generate electricity in the future. Here, we are only concerned with its use as an actinide (specifically, transuranic actinide) burner. For this application the core could be redesigned to reduce the breeding ratio to less than 1. Some proponents say that values as low as 0.2 could be attained (Reference 1), but others assert safety considerations would make the practical limit about 0.6. (Reference 2). With a breeding ratio of less than 1, the reactor would produce less actinides than it burns, and so with enough burner reactors it would be possible to burn up (i.e., fission) the transuranic actinides that are accumulating in spent light water reactor fuel. If enough of the light water reactor fuel actinides were consumed, the geological repository capacity requirements and the long-term health risks of the repository might be reduced (Reference 3). A reprocessing plant for spent light water reactor fuel would be required to prepare the light water reactor actinides for burning. The uranium would be separated, and then stored or recycled. Most of the actinides and some fission products (lanthanides) would be made into fuel for the ALMR. The remaining fission products and a small amount of actinides would be removed and disposed of as high level waste in a geological repository. In addition to ALMRs and reprocessing plants for light water reactor fuel, ALMR fuel fabrication plants and reprocessing plants for ALMR fuel would be required (Reference 4). The residual fission product and actinide waste would go to a geological repository. Some suggest removal of cesium and strontium from that waste, and temporary surface or subsurface storage (50 to 100 years) to allow the cesium and strontium to decay to reduce the heat load introduced to the geological repository. Is a breeder program, viable on its own merits, a prerequisite to an actinide burning ALMR program? All the people we heard from who commented on this point, including ALMR project participants, felt it made no sense to develop and deploy ALMRs solely for actinide burning. The breeder will be introduced when public policy, licensing, and economic considerations, such as the cost and availability of uranium, justify it. The ALMR proponents and some others felt that if the United States had a healthy breeder program, then it might be possible and justified to modify some or all of the breeder reactors to be actinide burners. What could be achieved by actinide burning and on what time scale? Actinide burning greatly reduces the actinides sent to the repository by storing them on the surface in ALMRs and slowly burning them. The fraction of the actinide inventory that could be consumed by this process depends upon the process decontamination factor, reactor fuel-cycle parameters, and length of time of ALMR operation. Based on ALMR project data, including actinide process decontamination factors specified as desirable goals by the ALMR project of

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Nuclear Wastes: Technologies for Separations and Transmutation 1,000 or more (References 1 and 8), the inventory of actinides that would otherwise accumulate in spent fuel from light water reactors could ultimately be reduced by a few hundred-fold in ALMRs operating continuously at constant power. Transuranic actinide inventory reduction is enhanced by a low breeding ratio, b (so that the ALMR generates fewer new actinides), and by a high process decontamination factor, g (because 1/g is the fraction of transuranic actinides that are lost to waste in each reprocessing cycle). Referring to Figure 1 (from Reference 7, based on Reference 8), we see that, independent of the design parameter b, and for g greater than 1,000, the time required to reach an inventory reduction factor of 10, equivalent to burning 90% of the actinides, would be more than 100 years, the time to reach an inventory reduction factor of 100 would be more than 1,000 years, and the time to reach an inventory reduction factor of 1,000 would be more than 10,000 years. This indicates that the actinide inventory reduction factor that can be achieved in a few centuries is nearer 10 than 100 or 1,000. A typical ALMR with breeding ratio of 0.62 would require about 30 metric tons of actinides for its initial charge and refueling for a 40-year life (Reference 5). The accumulated actinides in U.S. light water reactor spent fuel by the year 2011 are estimated as about 600 metric tons. Thus, even if light water reactors are phased out, about 20 ALMRs would be required to treat the actinides in U.S. light water reactor spent fuel on hand in 2011. The actinides in those 20 ALMRs at end of life would have to be burned in the next generation of about 10 ALMRs, and so on until the remaining actinides are insufficient to fuel one ALMR; those remaining actinides would go to a repository. If the light water reactor economy persists, many more ALMRs will be required for a longer time. What would be the effect on the radiation-induced health risks? The effect of actinide burning on radiation-induced health risks depends on just which isotopes contribute most to long term health risks due to their possible leakage from the repository. The long-lived actinides have a greater potential for radiation-induced health impact than do short-lived fission products after about 300 years, but the long-lived isotopes of technetium and iodine are also of concern. The health risks depend not only on the toxicity of the material but also on how rapidly it spreads into the environment. It turns out under all planned repository conditions that the actinides are much less soluble than the long-lived fission products. Thus, for solubility-limited repository scenarios, the fission products dominate the health effects, and burning of the actinides produces little or no reduction in the health risk. However, in invasive scenarios such as those involving human intrusion, the actinides are expected to dominate risk and a benefit is obtained from a reduction in actinide content of the waste. If we assume that any ALMR introduced into the electric utility grid would replace a light water reactor, use of the ALMR would allow already-mined depleted uranium or uranium from spent fuel to be used instead of natural uranium. Then the associated reduction in radioactivity from radon and other components in uranium ore would be expected to more than compensate for radioactivity released as a result of reprocessing for the ALMRs (Reference 3). On the other hand, the current ALMR flow sheets show technetium-contaminated uranium as a by-product of pyroprocessing of light water reactor spent fuel (References 1 and 5). Although we have not studied

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Nuclear Wastes: Technologies for Separations and Transmutation Figure 1 (from Reference 7, Figure 4-9, based on Reference 8) Ψ is the ratio of (inventory of transuranic actinides at time τ in spent fuel from the LWR at constant power, with no ALMR) to (inventory of transuranic actinides in the ALMR at constant power, in the ALMR fuel cycle, and in radioactive waste at time τ).

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Nuclear Wastes: Technologies for Separations and Transmutation the fate of this uranium, it appears that it may have to be placed in the repository because of its potential health risk. Because of increased fuel cycle activities, there might also be increases in risk due to potential fuel cycle accidents; we have seen no estimate of this. Proponents of the ALMR think the small unit size of its modular construction makes it safer (due to low coolant pressure and decay heat removal by natural convection) than a conventional light water reactor (Reference 2). If true, this would reduce risk. What licensing or regulatory problems may be encountered? Significantly reducing the total inventory of light water reactor-produced actinides by ALMR actinide burners will require an extensive, fully deployed ALMR system. As proposed, such a system would consist of ALMRs with associated ALMR reprocessing facilities, fuel fabrication facilities, and one or more facilities for reprocessing light water reactor spent fuel. In addition, storage and disposal facilities must be provided for the new waste streams, some of which will be high-level waste streams, produced by the ALMR system. Each of these facilities must be licensed. In the U.S., the Atomic Energy Commission granted operating licenses in the 1960s to one fast breeder reactor, Fermi I, and to the reprocessing plant at West Valley, New York. The licensing processes for any reactor or other nuclear facility are likely to be difficult and contentious; this is especially likely for new types of facilities such as the ALMR and its associated reprocessing plants. Adequate opportunity for U.S. Nuclear Regulatory Commission staff to perform generic rule-making, review standard designs and establish regulatory guides would be mandatory for the ALMR to succeed. Strong local intervention could be expected for each facility. How would actinide burning affect the need and schedule for the first geological repository? The statutory limit for the first repository is 70,000 metric tons of uranium until such time as the second repository is in operation. Of this amount, about 63,000 metric tons of uranium is expected to be light water reactor spent fuel, containing about 600 metric tons of transuranic actinides. This corresponds to the amount of spent light water reactor fuel projected to be discharged in the U.S. through the year 2011. In the actinide burning cycle, a repository would still be required. The repository would receive canisters of high-level waste containing mostly fission products and relatively small quantities of actinide waste from light water reactor fuel and reprocessing of existing defense wastes. Current estimates are that the fission products and remaining actinides would require about the same number of canisters as in the once-through spent fuel cycle (Reference 7, Table 4-5). Hanford defense wastes contain a much smaller amount of transuranics (a total of approximately 500 kg of transuranic actinides); Hanford plans to concentrate and vitrify the fission products and actinides for deep geological disposal. Again, removing the transuranics by transmutation does not appear to reduce the number of waste canisters, although chemical separation can greatly decrease the number of canisters of Hanford defense wastes. The ALMR

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Nuclear Wastes: Technologies for Separations and Transmutation high-level waste may be in a form different from spent fuel and defense waste (Reference 7); if so, an extensive research program would be required to characterize the ALMR high-level waste before it could be shown to be acceptable for emplacement at the repository. The primary thermal impact of transuranic actinide removal is the formation of a waste which cools to moderate temperatures after a few hundred years instead of thousands of years. At early times, the thermal output is dominated by Cs-137 and Sr-90 with about 30 yr half-lives. Because of this, for the initially emplaced waste, power density and repository operational heat issues are not changed substantially by actinide removal. The time duration of the thermal excursion and the maximum temperature reached are both substantially reduced by actinide removal. In some scenarios, capacity increases over time could be greater with actinide removal because of reductions in the long-term thermal output. If it is found desirable to keep repository temperatures low, removal of the actinides is beneficial. However, reduced heat generation may be undesirable in a repository in unsaturated rock, such as that at Yucca Mountain, where near-field temperatures above the boiling point of water may be beneficial for an extended time. Additional reduction in the required disposal area could result from removal of cesium and strontium, but separate surface or subsurface storage of these elements would be required for an extended time. Other engineering measures may also substitute for or add to the potential repository area reductions mentioned above. The current schedule for the first geological repository is determined by actions necessary to characterize the site and submit a license application in 2001 with repository operations beginning in 2010. The schedule for development of the ALMR system, as proposed, indicates that the first reactor and associated ALMR fuel reprocessing plant would provide modified high-level waste around 2020. Achieving this would require the development, design, licensing, and construction of the reprocessing plant and waste fixation plant for light water reactor spent fuel. The ALMR system will directly affect the licensing of the repository in that the resulting waste form must be certified as part of the repository license. This and other related public policy and institutional factors might introduce uncertainty and potential delays into the repository schedule. However, it may be possible, after initial licensing has been obtained and operation of both the repository and the ALMR system have begun, to modify the repository license to accommodate changes in waste form specification and concomitant repository operations. This could allow a decoupling between the licensing schedules of the ALMR and the repository. Thus, the General Electric Company licensing schedule for high-level wastes from the ALMR to the repository may not affect the repository schedule. However, the ALMR could still affect the repository schedule. The ALMR project expects major commitments to design and construction of reactor and reprocessing plants in 2002-2005 (Reference 2), as early as eight years before the 2010 opening of the repository. Therefore, under this scenario, there would be no reason to send light water reactor spent fuel to the repository; the fuel could be stored at the light water reactor site or at an interim storage facility until needed for ALMRs. Hence, successful development of the actinide-burning ALMR on the planned schedule makes it unnecessary to load commercial high-level waste into the repository until 2020, when the

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Nuclear Wastes: Technologies for Separations and Transmutation first waste from reprocessing of light water reactor spent fuel for the ALMR would be ready for emplacement (Reference 2). What are the costs of actinide burning? The feasibility of an actinide-burning ALMR is strongly affected by the unit cost of reprocessing light water reactor spent fuel. Such cost is uncertain and is likely to be high because of several factors, especially: (1) the low concentration of actinides in light water reactor fuel, (2) the relatively early state of development of the reference pyro-chemical process for light water reactor fuel, (3) the uncertainty of capital costs for all the facilities involved, and (4) the wide variability in the methods and costs of financing an industrial-scale reprocessing facility in the U.S. The large uncertainty about costs in information presented to the Panel has yet to be resolved. Summary This report summarizes the Panel's current information concerning actinide burning in ALMRs and the possible repository impacts. Because we are still in the fact-finding stage of our studies, no conclusions have been drawn about this technology; it and other technologies will now be analyzed by the Panel.

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Nuclear Wastes: Technologies for Separations and Transmutation REFERENCES 1 Personal communication in presentation to Transmutation Subpanel by Yoon Chang, Director of the Integral Fast Reactor Program, Argonne National Laboratory, Idaho Falls, 13 March 1992. 2 Personal communication in presentation to Transmutation Subpanel by Marion Thompson, Manager of Advanced Liquid Metal Reactor Program, General Electric Company, 13 March 1992. 3 Michaels, G. E. Impact of Actinide Recycle on Nuclear Fuel Cycle Health Risks, ORNL/M-1947, to be published June 1992. 4 McPheeters, C. C., and R. D. Pierce. Nuclear Waste From Pyrochemical Processing of LWR Spent Fuel for Actinide Recycling, ANL-IFR-165, to be published June 1992. 5 Pigford, T, and J. S. Choi. Inventory Reduction Factors for Actinide-Burning Liquid-Metal Reactors, Trans. Am. Nuc. Society 64, 1991. 6 Ramspott, L. D., J. Choi, W. Halsey, and A. Pasternak, Lawrence Livermore National Laboratory. Impacts of New Developments in Partitioning and Transmutation on the Disposal of High-Level Nuclear Waste in a Mined Geologic Repository. March 1992. Report No. UCRL ID-109203. 7 Johnson, T. R. Characteristics of IFR High Level Waste Forms, ANL-IFR-164, March 1992. 8 Pigford, T. H. and J. S. Choi. Reduction in Transuranic Inventory by Actinide Burning Liquid-Metal Reactors, UCB-NE-4183, June 1991.

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Nuclear Wastes: Technologies for Separations and Transmutation Panel on Separations Technology and Transmutation Systems Norman C. Rasmussen, Chairman, Massachusetts Institute of Technology Thomas J. Burke, The Johns Hopkins University Gregory Choppin, Florida State University Allen G. Croff, Oak Ridge National Laboratory Harold K. Forsen, Bechtel National, Inc. B. John Garrick, PLG, Inc. John M. Googin, Martin Marietta Energy, Inc. Hermann A. Grunder, Continuous Electron Beam Accelerator Facility L. Charles Hebel, Xerox PARC Thomas O. Hunter, Sandia National Laboratories Mujid Kazimi, Massachusetts Institute of Technology Edwin E. Kintner Rolland A. Langley, BNFL Inc. Edward Mason Fred McLafferty, Cornell University Thomas H. Pigford, University of California at Berkeley Dan Reicher, Natural Resources Defense Council James E. Watson, University of North Carolina Susan D. Wiltshire, J.K. Associates Staff Carl A. Anderson, BRWM Associate Staff Director Lisa J. Clendening, Project Assistant

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Nuclear Wastes: Technologies for Separations and Transmutation Separations Technology and Transmutation Systems Subpanel on Separation Fred McLafferty, Chairman, Cornell University James Buckham, Allied General Nuclear Gregory Choppin, Florida State University Melvin S. Coops Gerhart Friedlander, Brookhaven National Laboratory John M. Googin, Martin Marietta Energy, Inc. Darleane C. Hoffman, Lawrence Berkeley Laboratory C. Judson King, III, University of California Rolland A. Langley, BNFL Inc. Robert A. Osteryoung, SUNY-Buffalo Raymond, G. Wymer, Oak Ridge National Laboratory Staff Douglas Raber, BCST Staff Director Scott Weidman, Senior Staff Officer Karen McMillan, Senior Project Assistant

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Nuclear Wastes: Technologies for Separations and Transmutation Separations Technology and Transmutation Systems Subpanel on Transmutation Edwin E. Kintner, Chairman Ersel A. Evans, Consultant, Pacific Northwest Laboratories Harold K. Forsen, Bechtel National, Inc. Hermann A. Grunder, Continuous Electron Beam Accelerator Facility William M. Jacobi Mujid Kazimi, Massachusetts Institute of Technology Glenn E. Lucas, University of California at Santa Barbara John C. Lee, University of Michigan Thomas H. Pigford, University of California at Berkeley Staff Mahadeven Mani, EEB Staff Director Kamal J. Araj, Study Director James J. Zucchetto (Study Director as of 5/22/92) Susanna Clarendon, Administrative Assistant

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Nuclear Wastes: Technologies for Separations and Transmutation Separations Technology and Transmutation Systems Subpanel on Integration Edward Mason, Chairman Thomas J. Burke, The Johns Hopkins University Allen G. Croff, Oak Ridge National Laboratory Harold K. Forsen, Bechtel National, Inc. B. John Garrick, PLG, Inc. L. Charles Hebel, Xerox PARC Thomas O. Hunter, Sandia National Laboratories Rolland A. Langley, BNFL Inc. Thomas H. Pigford, University of California at Berkeley Dan Reicher, Natural Resources Defense Council James E. Watson, University of North Carolina Susan D. Wiltshire, J.K. Associates Staff Carl A. Anderson, BRWM Associate Staff Director Lisa J. Clendening, Project Assistant

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