The FuTure oF nuclear Fuel cycle - MIT Energy Initiative

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advanced technology opportunities The united States has not made significant investments in understanding fuel cycle options for several decades. In this time new options (appendix B) with potentially better characteristics but major uncertainties have been partly developed. Several of these are described here. LWRs with modified cores. The appeal of liquid-metal cooled fast reactors (lMFrs) is that they enable a closed fuel cycle that extracts 50 times as much energy from uranium as does the once-through (open) fuel cycle of existing lWrs. But demonstration lMFrs to-date have been more expensive compared to existing light water reactors (lWrs) and so have never been commercialized. The sodium fast reactor was chosen in the 1970s as the preferred sustainable reactor because of its high conversion ratio. our analysis indicates that a lower conversion ratio near unity is preferable for a sustainable reactor. advances in the design now indicate that a hard-spectrum lWr could have a conversion ratio near unity and be a sustainable reactor. Such modified-core lWrs are likely to be less costly to develop than lMFrs, because only the reactor core needs to change, and may be more economic to operate. Moreover, this approach may provide the option of using some of the existing reactor fleet for a closed, sustainable fuel cycle that would greatly extend uranium resources. There has been significant work in several countries on such modified-core lWrs, but additional research and demonstration would be required to determine commercial viability. Advanced High-Temperature Reactors. In the last decade, a new reactor concept has been proposed that uses liquid fluoride salts as coolants and graphite-matrix coated-particle fuel. The reactor combines the coolant developed for molten-salt reactors and the fuel developed for gas-cooled high-temperature reactors. one variant uses pebble-bed graphite-matrix coated-particle fuel. With this option, the fuel pebbles would not be fixed in place as with a conventional fuel assembly, but would slowly move through the reactor core. This allows continuous re-fueling and three dimensional optimization of the reactor over time, enabling novel fuel cycles. For example, such a reactor may be operated in a combined uranium-thorium fuel cycle in a once-through mode or may have a high conversion ratio (near unity) if operated with a closed fuel cycle. The reactor would operate at low pressures and with high coolant temperatures resulting in increased efficiency of electric power generation. Thus such reactors could have lower capital costs and enhanced safety and nonproliferation characteristics relative to lWrs. rd&d would be needed to determine long-term commercial viability. This reactor is also called the fluoride salt high-temperature reactor. Uranium from Seawater. Seawater contains about four billion tons of uranium, enough to support thousands of reactors for thousands of years. recent Japanese research suggests that the cost of obtaining uranium from seawater may ultimately be low enough to be commercially feasible, which would enable once-through fuel cycles for centuries. The economic viability of this option depends upon the long-term durability in seawater of the ion exchanger that is used to separate uranium. r&d is required to determine the potential for seawater uranium. Nuclear renewable futures. historically, nuclear energy has been considered as a source of base-load electricity, which constitutes a quarter to a third of the world’s total energy needs. however, there are additional candidate markets, such as meeting peak and other variable electricity demands by coupling base-load nuclear reactors to huge energy storage systems, or production of renewable liquid fuels in nuclear-powered biorefineries. Viability depends upon both the economics of nuclear power and successful development and commercialization of technologies such as gigawatt-year heat storage, high-temperature electrolysis for hydrogen production, and hydrocracking of lignin. developments in this area could significantly expand lowcarbon energy options for the united States and may drive market requirements (temperature of delivered heat, reactor size, etc.) that, in turn, would drive reactor and fuel cycle decisions. chapter 10. recommended analysis, research, development, and demonstration Programs 141
There are large financial and policy incentives for cooperative international programs where different nations build different research infrastructure facilities with agreements for longterm sharing. It would enable the U.S. and others to examine multiple fuel cycle options through demonstration projects before making major long-term commitments. Unlike in the past, most new nuclear reactor and fuel cycle research is being done elsewhere (France, Japan, China, India, Russia, and South Korea)—a very different environment from that in which the U.S. led nuclear energy R&D. Large-scale cooperation has been historically difficult to achieve. However, research areas such as waste management science and technology serve the global interest and will in many cases be employed by national authorities. This may be a fruitful avenue for collaboration with less intellectual property complications than reactor technology development. CitationS and noteS 1. U.S. Department of Energy Science Based Nuclear Energy Systems Enabled by Advanced Modeling and Simulation at the Extreme Scale, E. Moniz and R. Rosner, Cochairs, Crystal City, Va., May 2009) 2. http://www.er.doe.gov/ascr/ProgramDocuments/ProgDocs.html 3. U.S. Department of Energy, Nuclear Energy Research and Development Roadmap: Report to Congress (April 2010) 4. Idaho National Laboratory, Required Assets for a Nuclear Energy Applied R&D Program (March 2009) 5. Safety regulations for nuclear power plants have been designed for LWRs. The regulations for LWR safety are not appropriate for other reactor technologies. The U.S. Nuclear Regulatory Commission is moving toward “technologyneutral” licensing where new technologies must meet the same safety goals but can use different approaches to meet those goals. However, cost and time to license any new technology is a major barrier to innovation and better systems—including nuclear systems with better safety, waste management, and nonproliferation characteristics. Federal funding in demonstration projects reduces the barriers for technologies with large social benefits but small economic ones to the companies commercializing such technologies. 142 MIT STudy on The FuTure oF nuclear Fuel cycle
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Other Reports in This Series The Fu
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MIT Nuclear Fuel Cycle Study Adviso
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vi MIT STudy on The FuTure oF nucle
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viii MIT STudy on The FuTure oF nuc
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Study Findings and Recommendations
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Recommendation We recommend that a
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p Innovative nuclear energy applica
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p In line with many of our R&D reco
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The “once through” or open fuel
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have been implemented slowly. This
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Recommendation We recommend that th
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oped policies for specific wastes r
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nuClear Fuel CyCleS The united Stat
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- The primary differences were in t
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Recommendation Integrated system st
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Table 1.2 Summary of R&D Recommenda
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18 MIT STudy on The FuTure oF nucle
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the once-through Fuel Cycle for lig
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tricity costs. Waste management cos
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Figure 2.3 partial recycle of lWr S
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history of the nuclear Fuel Cycle B
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• What is the impact of timing of
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nuclear fuel cycles, the wastes (SN
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Because ore demand is closely coupl
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eStimatinG Future CoStS oF uranium
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Figure 3.3 relative uranium Cost vs
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Figure 3.4 100 year price trend for
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Stockpiling If supply interruption
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CitationS and noteS 1. Uranium 2007
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If SNF is to be shipped, typically
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a policy that maintains fuel cycle
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Dry cask storage is used for short
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For decommissioned sites, our econo
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with its attractiveness of jobs and
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2. The United States should create
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Table 5.1 United States Waste Class
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table 5.3 examples of operational G
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Waste Isolation Pilot Plant The uni
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Successful repository programs are
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designed with limited SNF storage c
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CitationS and noteS 1. A Handbook f
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energy spectrum centered at higher
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light Water reactor Fuel technical
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(fertile-free) to CR=1.0 (break-eve
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license. However, fuel reprocessing
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Figure 6.4 densification Factors as
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As expected, the breeder installed
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Figure 6.8 shows the development of
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Table 6.8 Uranium Cost in $/kg, Sta
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Figure 6.11 location of the tru inv
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Page 113 and 114: Summary oF ConCluSionS Among the in
Page 115 and 116: [hoffman et al., 2006] e.a. hoffman
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Page 123 and 124: Table 7.4 The LCOE for the Fast Rea
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Page 131 and 132: Figure 8.1 Weapons-usability Charac
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eaCtor teChnoloGieS Nuclear power e
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via 239 Pu and 240 Pu, and then the
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urnups, but the gap between the nec
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(~700°C) with higher thermal-to-el
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There are several unique consequenc
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performance goals can be achieved.
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is that it will be many decades bef
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system [1]. The nuclear power plant
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The HTRs can be used to provide hig
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[http://nextgenerationnuclearplant.
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CitationS and noteS Brinkmann, H. U
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The analysis is based on the assump
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considerations discussed above. We
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In our analysis we make the explici
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Figure d.4 transmutation Consequenc
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Figure d.5 breeder Consequences LWR
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facilities. These concerns are the
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Technological applicability Geologi
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It must be noted, that net risks an
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p Once-through fast reactor fuel. T
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Table E.1 Recycling Plant Functions
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Table E.3 Conventional Fuel Fabrica
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eactor. A summary of inputs from in
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