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--> 1 Introduction This chapter presents a brief introduction to the study, identifying important aspects of the decontamination and decommissioning (D&D) of the gaseous diffusion plants (GDPs) that comprise the nation's uranium enrichment facilities.1 The discussion covers the objectives of the study, a brief history and description of the gaseous diffusion facilities, the establishment of the United States Enrichment Corporation (USEC) and the D&D cost estimates developed to support the transfer of management of the enrichment facilities from the federal government to the corporation, the implications the Energy Policy Act of 1992 (EPACT) for D&D, and a brief overview of the committee's report. Study Background And Objectives EPACT, signed into law on October 24, 1992, calls for the National Academy of Sciences to conduct a study and provide recommendations for reducing costs associated with the D&D of the nation's uranium enrichment facilities located at Oak Ridge, Tennessee; Paducah, Kentucky; and Portsmouth, Ohio (U.S. Congress, 1992).2 Following EPACT, the U.S. Department of Energy (DOE) Assistant Secretary for Environmental Restoration and Waste Management requested that the National Research Council (NRC), principal operating arm of the National Academy of Sciences, undertake such a study. In response, in November 1993, the NRC established the Committee on Decontamination and Decommissioning of Uranium Enrichment Facilities to study opportunities for cost reduction in the D&D of the nation's GDPs. The committee was also charged with assessing options for the disposition of a large inventory of depleted uranium hexafluoride (DUF6) stored outdoors in steel cylinders at each of the sites.3 As part of this effort, the committee reviewed previous cost studies for the D&D of the GDPs and for the disposition of the DUF6 inventory. The committee was not asked to develop specific D&D cost estimates. (Appendix A contains the committee's complete statement of task.) 1 D&D activities include characterization, decontamination, dismantling, and disposition of a facility's equipment and structures, as well as waste treatment. Decontamination consists of those activities that reduce levels of radioactive and/or hazardous contamination in or on materials, structures, and equipment (DOE, 1994). 2 The Ohio plant is actually located in Piketon, Ohio, about 20 miles north of Portsmouth, but it is generally referred to as the Portsmouth site. 3 Depleted uranium has a 235U isotopic content less than the 0.71 percent by weight in natural uranium.
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--> The committee's study identifies opportunities for cost reduction vis-à-vis existing cost estimates. The study also considers practices and approaches that would likely reduce D&D costs in a broader context. The only gaseous diffusion plant that has undergone D&D for which cost information is available is a British Nuclear Fuels (BNFL) plant at Capenhurst in the United Kingdom. This experience and its reported cost data served as an important benchmark in addressing the costs of D&D of the U.S. plants. The present study is restricted to the D&D of the buildings and equipment comprising the GDPs. As defined by the statement of task, the study excludes consideration of environmental restoration activities, such as cleanup of soils and groundwater at the three enrichment facility sites. Also excluded are the gaseous centrifuge facilities at the Oak Ridge and Portsmouth sites that were never used for commercial production. These facilities do not represent a major part of the D&D costs at these sites, but some of this study's recommendations are pertinent to their D&D as well. The committee has considered the coordination and integration of D&D, environmental restoration, and management options for the DUF6 for cost-effective management of the cleanup program. The U.S. Uranium Enrichment Enterprise Natural uranium found in ore deposits consists of the three isotopes uranium-234, uranium-235, and uranium-238 (234U, 235U, and 238U). 234U is found in trace amounts; 235U and 238U occur in abundances of about 0.71 and 99.28 percent, respectively. The percent by weight of 235U to all uranium atoms is termed the percent enrichment of 235U in uranium; thus, for natural uranium the enrichment level is 0.71 percent. Many applications require enrichment levels above 0.71 percent, typically from 2 to 5 percent for light-water power reactors and 20 percent and greater for such applications as research reactors, compact reactors for naval use, and nuclear weapons. The U.S. uranium enrichment program was created in the 1940s to produce enriched uranium for military applications, such as nuclear weapons. The three GDPs were used primarily for this mission through the 1960s, but in 1964 Congress authorized the private ownership of enriched uranium for commercial uses. After this time, the amount of enriched material delivered to the commercial sector grew rapidly, making up 90 percent of all the separative work units (SWUs) produced in 1974.4 Beginning in 1968, the production capacity of the three plants was increased in response to demand from the commercial nuclear power sector. The U.S. enrichment program has relied on the gaseous diffusion process. The feed material for a GDP is uranium hexafluoride (UF6) gas, which is produced at other industrial facilities using natural uranium and delivered to the GDPs. The enriched UF6 product from the GDPs is sent to other plants for fabrication into uranium products such as reactor fuel. A DUF6 4 Enrichment capacity is typically measured in SWUs (see Glossary).
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--> gas stream resulting from the enrichment process is collected and stored in cylinders, which are placed in outdoor storage yards at the three GDP sites (see Chapter 7).5 The Oak Ridge GDP was built between 1942 and 1945 under the auspices of the Manhattan Engineering District Project and began operation in 1945. The Oak Ridge GDP had the capability to enrich uranium up to 90 percent. The second plant, the Paducah GDP in Kentucky, was built between 1951 and 1955 to produce uranium to enrichment levels no greater than 2 percent. The third plant, the Portsmouth GDP in Ohio, began operation in 1956 and was designed to accept natural uranium feed, as well as the product from either the Oak Ridge or the Paducah GDP, and produce enriched uranium ranging from 2 percent to greater than 97 percent 235U. When all three plants were operational, they constituted an integrated production complex (see Figure 1-1 for the geographic locations of the plants). The Oak Ridge GDP ceased production of highly enriched uranium (with enrichment levels greater than or equal to 20 percent) in 1964 because of insufficient demand. Low-enriched uranium (with enrichment levels less than 20 percent) was produced until 1985, when the plant was placed in a standby mode because of declining demand for low-enriched uranium from the commercial nuclear power sector; the plant was permanently closed in 1987. Since cessation of enrichment operations at the Oak Ridge GDP in 1985, the two plants at Portsmouth and Paducah have constituted a two-site complex. Both plants receive natural and partially enriched feed. The Portsmouth high-enrichment section has been closed since November 1992. The enrichment level capacity of certain parts of the Paducah plant was increased to 2.75 percent in 1995.6 The cost estimate prepared by Ebasco Environmental (Ebasco) assumes both operating plants would close in 2005, at which time other lower cost enrichment technologies would be expected to be used in the United States. The time of closure of the plants is uncertain, depending on the world uranium enrichment market and competitive forces. The Ebasco estimate assumed a sequential cleanup, Oak Ridge followed by Paducah, with Portsmouth last. The Ebasco cost estimate assumed the physical decommissioning to occur from 2002 to 2030 (DOE, 1991a). If either the Paducah or Portsmouth plant were to close sooner, there might be cost or other incentives to change the sequence or schedule of D&D activities for the three plants. The United States Enrichment Corporation EPACT restructured the government-owned uranium enrichment enterprise, which was under the management of DOE, by creating the USEC. The corporation was established as of 5 This depleted UF6 is sometimes referred to as "tails," although that term is not universally favored (Lemons et al., 1990). 6 Personal communication from Michael Buckner, Lockheed Martin Utility Services, Paducah, Kentucky, to James Zucchetto, NRC, June 1, 1995. The USEC has contingent approval from its current regulator, DOE, to operate at this enrichment level, but as of January, 1996 no uranium has been enriched at this plant above 2 percent. Modifications to the plant required to satisfy the contingent approval are expected to be in place by the time the Nuclear Regulatory Commission assumes regulatory authority over the plant, sometime in 1996.
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--> FIGURE 1-1 The geographic relationship of the three GDPs. July 1, 1993, as a wholly owned government corporation that is an agency and instrumentality of the United States. USEC is structured as a self-financing entity "to operate as a business enterprise on a profitable and efficient basis" to "help maintain a reliable and economical domestic source of uranium enrichment services." Ownership of the corporation is to be transferred eventually to private investors (U.S. Congress, 1992). The corporation is currently leasing the Paducah and Portsmouth GDPs and related property from DOE for a period of 6 years from the transition date (July 1, 1993). The lease does not apply to those DOE facilities at Portsmouth necessary for the production of highly enriched uranium. Lockheed Martin Utility Services (formerly Martin Marietta Utility Services [MMUS]) is the USEC managing contractor for the uranium enrichment plants (USEC, 1993). The organization is responsible for plant operation and maintenance in accordance with work programs and budgets prepared in cooperation with the USEC. Lockheed Martin Energy Systems (formerly Martin Marietta Energy Systems [MMES]) is DOE's management contractor for environmental restoration and waste management activities at the Paducah and Portsmouth sites. USEC is not involved with the nonoperating facilities at the Oak Ridge GDP. The management and operations contractor at the Oak Ridge GDP is Lockheed Martin Energy Systems.
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--> EPACT stipulates that DOE is responsible for any cost of D&D with respect to conditions existing before the transition date.7 The corporation is obligated to return the facilities in the same condition as they were received and to remove deposits of uranium that represent a criticality risk (DOE, 1993).8,9 This arrangement is not necessarily optimal for subsequent D&D efforts. Substantial uranium deposits would probably still remain in the process equipment. A large percentage of these deposits could be removed from the intact, functioning cascade through a gaseous decontamination process, or through other approaches. This was not done for a substantial part of the Oak Ridge plant when it stopped operations (see chapters 2 and 3). The degree to which gaseous decontamination, or other approaches, should be used at the Paducah and Portsmouth plants to reduce the amount of uranium deposits will involve calculating a number of tradeoffs to determine the most cost-effective approach for D&D of the cascade equipment (see chapters 3 and 6). The D&D Fund EPACT established a Uranium Enrichment Decontamination and Decommissioning Fund (D&D Fund) to finance cleanup efforts of the uranium enrichment facilities by the federal government. EPACT specifies that payments per fiscal year of $480 million, adjusted for inflation, shall be made into the D&D Fund for 15 years, with up to $150 million per year from a special assessment on electric utilities, proportional to their purchases of uranium enrichment services (measured in terms of SWUs) from DOE through October 24, 1992, and the balance of the payments from annual appropriations from the federal treasury. The special utility assessment is thus capped at $2.25 billion. If all payments are made as planned, a total of $7.2 billion will be contributed to the D&D Fund. EPACT stipulates that all D&D activities are to be paid for from the D&D Fund until such time as the Secretary of Energy certifies and Congress concurs, by law, that such activities are complete. EPACT also stipulates that the annual cost of remedial action at the gaseous diffusion facilities shall be paid from the D&D Fund to the extent that the amount available in the fund is sufficient. To the extent the amount in the fund is insufficient, DOE shall be responsible for the cost of remedial action (U.S. Congress, 1992). A recent court decision has raised questions about the expected utility contributions (Newman, 1995). 7 EPACT stipulates: "The payment of any costs of decontamination and decommissioning, response actions, or corrective actions with respect to conditions existing before the transition date, in connection with property of the Department leased … shall remain the sole responsibility of the Department." 8 Section 4.4 of the USEC lease specifies in subparagraph (b): "… Remove solid deposits of UO2F2/UF4 to the extent necessary to prevent criticality …;" and in subparagraph (e): "Place structures to be returned at the facility in a safe secure condition, removing any immediate threats to human health and safety. …" 9 In a nuclear criticality event, an assemblage of enriched uranium results in a self-sustaining nuclear chain reaction generating heat, radioactive contamination, and gamma and neutron radiation. Usually a criticality event is self-limiting because the energy release disrupts the geometric configuration of the enriched material that caused the criticality. If the assemblage reforms again, another criticality event will occur. Hence, some criticality events are pulsed events.
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--> The Challenges Of A D&D Effort The GDPs constitute a complex of large buildings, with hundreds of acres of floor area and thousands of large pieces of equipment (see figures 1-2 and 1-3 and Chapter 2). In addition to the process buildings, there are auxiliary buildings, electrical switchyards, and connecting piping and electrical systems. The process equipment at the nonoperating plant at Oak Ridge contains significant quantities of solid deposits of uranium of all degrees of enrichment. Large quantities of hazardous substances, such as asbestos and polychlorinated biphenyls (PCBs), will have to be dealt with at all three sites. Despite the large scale of the facilities, the effort will essentially be a large disassembly and deconstruction project. The repetitive and common designs throughout the GDPs should allow for economies of scale in D&D, and there is a potential to FIGURE 1-2 Photograph of the interior of a process building showing the repetitive arrangement of the cascades. SOURCE: Briefing material from the committee meeting at the Oak Ridge GDP, February 3-4, 1994.
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--> FIGURE 1-3 The Oak Ridge GDP site. SOURCE: Briefing material from the committee meeting at the Oak Ridge GDP, February 3-4, 1994. recycle significant quantities of metals with commercial value. Careful removal of enriched uranium deposits will be required to avoid criticality accidents and to ensure material accountability. These deposits, some highly enriched as in the K-25 building at Oak Ridge, present a distinguishing problem, namely, the prevention of a criticality accident, which is germane to few other facilities requiring cleanup. Requirements for preventing criticality will increase costs at Oak Ridge and Portsmouth compared to Paducah, where deposits are at much lower enrichment levels.
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--> Perhaps the greatest challenge to reducing D&D costs is effectively managing this large effort, which involves numerous regulatory authorities, spans several decades, and faces many uncertainties. A number of issues need resolution: the regulatory requirements that define to what extent the sites must be cleaned up; the future uses of the sites; the extent to which materials can be decontaminated and recycled; and the disposal costs and site location for wastes resulting from D&D. There is a complex multi jurisdictional regulatory regime under which D&D must be undertaken. Stakeholders must be brought into D&D planning. The amount of money that will be available from the D&D Fund could affect the schedules and timing of D&D operations. These uncertainties have important implications for the success of the D&D program and its associated costs. DOE is also responsible for a total of over 500,000 metric tons of DUF6 contained in about 46,000 steel cylinders in outside storage yards at the three sites. Future uses have been suggested for this material (see Chapter 7). However, concern about deterioration of the storage cylinders over time, which could result in the release of hazardous material, and difficulties in cylinder handling, could very well favor conversion of the DUF6 into a more stable chemical form. It was not evident to the committee whether DOE intends to closely coordinate the disposition of the DUF6 with the D&D of the facilities. D&D Costs Financial assessments were made by the federal government in developing a plan for restructuring DOE's uranium enrichment enterprise. The assessments required the cost for environmental cleanup of the three uranium enrichment sites including the D&D of the facilities (i.e., the major buildings and structures housing the GDPs), remedial actions at areas outside of the major buildings and structures, and disposition of DUF6 held in storage. An independent financial assessment by Smith Barney, Harris Upham & Company (1990), recommended that a complete D&D cost study be undertaken, based on the conclusion that the costs associated with D&D would be high and significantly affect the economic viability of the uranium enrichment enterprise and any proposed restructuring (Timbers, 1990). The Smith Barney study also recommended that D&D costs associated with operations prior to any transfer of ownership should remain a direct liability and obligation of the federal government. Following on this financial assessment, DOE commissioned two cost estimates for D&D of the GDP facilities (see Chapter 4). Ebasco prepared a preliminary cost estimate that assumed "prompt dismantlement," with the facilities to be cleaned of radioactive and hazardous materials and restored to a condition such that a future occupant would not be exposed to harmful substances (DOE, 1991a). An initial D&D cost estimate by Ebasco amounted to almost $46 billion, but a set of reevaluations, redefining the scope of the effort, resulted in a final estimate of $16.1 billion (1992 dollars), not including environmental restoration activities for the sites or management and disposition of the stored DUF6 (Table 1-1). TLG Engineering (TLG) was contracted by DOE through Systematic Management Services to "estimate the costs of decommissioning … from the standpoint of a Decommissioning Operations Contractor performing the work at the lowest competitive cost"
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--> TABLE 1-1 Estimated Costs for Prompt Dismantlement of the Gaseous Diffusion Plants (billions of 1992 dollars) Contractor Oak Ridge Paducah Portsmouth D&D Total Ebasco 7.5 3.3 5.3 16.1 TLG 7.3 3.1 3.5 13.9 SOURCE: DOE (1991a; 1991b). (DOE, 1991b). Some assumptions were different from those used in the Ebasco study. TLG developed an estimated cost for the D&D of the three GDPs of about $13.9 billion (see Chapter 4). MMES estimated the cost of converting the stored DUF6 at the three sites to uranium oxide and aqueous hydrogen fluoride (HF) at between $1.3 billion and $4 billion (1992 dollars) (see Chapter 7; Charles et al., 1991; DOE, 1991a). This study assumed an inventory of about one million tons of DUF6, including both the DOE legacy and future accumulations estimated to be produced through 2005 from the operation of the plants. Organization Of The Report As seen above, the D&D of the GDPs and associated cost estimates involve a number of issues, such as the state of the sites and the scope and extent of cleanup, technologies for accomplishing the D&D, and the regulatory environment and standards under which the D&D will occur. Chapter 2 of the report discusses the current situation at the GDP facilities describing the gaseous diffusion process and the equipment used for uranium enrichment, the buildings and sites, the radioactive and nonradioactive contaminants in the buildings that have to be removed, and the risks subsequent to closure of the facilities. Chapter 3 addresses the technologies that could be, or have been, used to accomplish D&D of GDPs, including those used by BNFL at the Capenhurst gaseous diffusion plant in the United Kingdom. Chapter 3 also identifies research and development needs. The committee has reviewed the Capenhurst experience in some detail because it represents the only GDP of design similar to that of the U.S. plants that has undergone D&D. Chapter 4 reviews the cost studies that have been prepared for the D&D of the U.S. GDPs, including the Ebasco and TLG estimates and an analysis of the Ebasco estimate by Science Applications International Corporation (SAIC). Major projected cost drivers in D&D are identified. The cost data reported for the actual D&D of the Capenhurst plant is also presented, along with a scaleup analysis the committee conducted that estimates the cost of D&D for the U.S. GDPs based on the Capenhurst experience.
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--> Chapter 5, on D&D program planning, emphasizes the point that D&D of the GDPs involves more than just technology. A number of groups and individuals (the stakeholders) have an interest in the process of D&D and in the eventual end states of the sites. Regulations play an important role in the cost of cleanup because they determine to what extent the facilities will need to be cleaned and whether recycling of materials to the commercial market will be allowed. Specification of different end states for the sites also has a significant impact on cost; for example, carrying out D&D of the buildings for reuse compared to removing radioactive and hazardous substances, demolishing the buildings, and burying all the waste. Chapter 5 also presents a D&D planning approach to minimize conflict and delays. Based on all the preceding material, Chapter 6 delineates opportunities for cost reduction grouped according to the categories used in the Ebasco cost estimate: program integration, radioactive and hazardous waste management, decontamination and decommissioning, and support facilities. Chapter 6 also addresses how changes in the cost estimate assumptions could lead to reduced costs. Chapter 7 addresses the issues, management options and related cost estimates for the DUF 6 inventory at the sites. The chapter also discusses potential uses for the DUF6 and evaluates technologies for conversion of the DUF6 into other chemical forms. Finally, Chapter 8 presents the committee's major recommendations. The appendices provide a variety of supporting material.
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--> References Charles, L.D., R.A. Joseph, D.E. Brashears, R. VanWinkle, and J.H. Pashley. 1991. Cost Study for the D&D of the GDPs: Depleted Uranium Management and Conversion. K/D-5940-F Oak Ridge, Tennessee: Martin Marietta Energy Systems. September. DOE (U.S. Department of Energy). 1991a. Environmental Restoration of the Gaseous Diffusion Plants. Technical Summary Document, vol. 1. Washington, D.C.: Ebasco Environmental and Main-1893 for the DOE. October. DOE. 1991b. Preliminary Cost Estimate for D&D of the Gaseous Diffusion Plants. Document S14-25-002. Bridgewater, Connecticut: TLG Engineering, Inc. for Systematic Management Services, Inc. for the DOE. September. DOE. 1993. Lease Agreement Between the U.S. Department of Energy and the United States Enrichment Corporation. Washington, D.C.: DOE. July 1. DOE. 1994. Decommissioning Handbook. DOE/EM-0142P. Office of Environmental Restoration. Washington, D.C.: DOE. March. Lemons, T.R., C.R. Barlow, J.M. Begovich, F.C. Huffman, P.M. Kannan, J.D. McGaugh, J.H. Pashley, J.J. Staley, W. J. Spetnagel, and L.D. Trowbridge. 1990. The Ultimate Disposition of Depleted Uranium. K/ETO-44. Oak Ridge, Tennessee: Uranium Enrichment Organization, Martin Marietta Energy Systems, Inc., for the DOE. December. Newman, P. 1995. Yankee Atomic wins cleanup case against DOE. The Energy Daily. July 5. 23(126): 4. Smith Barney, Harris Upham & Co. 1990. United States Enrichment Enterprise: An Independent Financial Assessment. Washington, D.C.: Smith Barney, Harris Upham & Co. for DOE. May. Timbers, W.H. Jr. 1990. Testimony on the Department of Energy's Uranium Enrichment Enterprise and the Independent Financial Assessment Prepared by Smith Barney before the Subcommittee on Energy Research Development Committee on Energy and Natural Resources, U.S. Senate, June 28, 1990. U.S. Congress. 1992. Energy Policy Act of 1992. Conference Report to Accompany H.R. 776. Washington, D.C.: U.S. Government Printing Office. USEC (United States Enrichment Corporation). 1993. Summary and Fact Sheet (for Portsmouth Gaseous Diffusion Plant). Piketon, Ohio: USEC. November.
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Representative terms from entire chapter: