The FuTure oF nuclear Fuel cycle - MIT Energy Initiative

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With few exceptions, the existing closed fuel cycle technologies require the separation of pure plutonium or plutonium/uranium mixtures from SNF before fabrication of new fuel because of technical and economic constraints in the production of new nuclear fuel assemblies. Nuclear fuel assemblies are highly engineered components that require extensive quality assurance. This is much easier to do this when starting with pure materials rather than with impure materials containing fission products with high radiation limits. In most cases separation of pure fissile materials such as plutonium is not a fundamental requirement of closed fuel cycles but rather a consequence of existing fuel fabrication technology limits. Different closed fuel cycles have radically different types of reactors and fuels; however, the same backend fuel cycle technologies are used for separating different types of SNF into product streams and converting wastes into acceptable waste forms for disposal. This is because all SNF contains the same actinides and fission products with the same requirements for acceptable waste forms. In contrast, the fuel fabrication technology is fuel cycle and reactor specific. A product slate is critical to the design, configuration, and operations of the separations and waste treatment units in a recycling plant. The product slate will depend on the SNF feed material, the selected recycling reactors (fast or thermal reactors), the recycle strategy (total or partial-closed cycle), fuel reactor fuel configurations (homogeneous or heterogeneous), type of recycled fuel (metal, oxides, other ceramics, etc.), as well as target materials/ configuration. Ultimately, it is the recycle fuel fabrication and waste disposal methods that provide the specifications for what are the form and composition of the products coming out of a recycling plant. Separations and Waste Treatment The larger the number of products desired from SNF, the more complex the recycling plant. A recycling plant incorporates separations to produce desired products and waste management facilities. Traditional functions encountered in recycling facilities are listed in Table E.1 for both aqueous and electrochemical (pyrochemical) processes. p Aqueous processing. The fuel is dissolved in a low-temperature aqueous acid solution with various organic extractants used to separate products from the aqueous solution. The process can be scaled to very large sizes (7000 tons SNF/year) p Electrochemical (pyrochemical) processing. The fuel is dissolved in a high-temperature salt with electrochemical methods used to “plate-out” metallic products. The process is usually operated as a batch process with multiple lines to meet throughput requirements. Commercially only one type of recycling facility exists, that which recovers plutonium from LWR spent fuel for production of MOX fuel (recycle of plutonium back to LWRs). Three complete commercial recycling plants have been built which include the separations and waste treatment portions, but all lack treatment for selected off-gases and tritiated water: p LaHague (France): 2 trains of 800 tons LWR SNF/year p Sellafield THORP (Great Britain): 1200 tons LWR SNF/year p Rokkasho (Japan): 800 tons LWR SNF/year appendix e: Status of Fuel cycle Technologies 231
Table E.1 Recycling Plant Functions area aqueouS FaCility FunCtion eleCtroChemiCal FaCility receiving cask unloading, assembly inspection and storage Feed Preparation chopping, leaching and dissolution chopping, shredding and load into baskets Gas handling and Purification System capture gases from dissolver and process operations removes oxygen and water from inert cell atmosphere and collects fission gases Separations recovery of variety of oxide products in solution recovery of metallic u and u/Tru product Product conversion Solidification consolidation (melting) equipment repair area for repair and maintenance of process and remote handling equipment and Maintenance Waste-form Production Storage Facilities Product Storage Facility conversion to waste forms acceptable for repository disposal, typically glass, treatment and storage of secondary waste, which may include cladding, hardware, llW, Tru, organics, process water, filters and failed equipment Production and packaging of metallic waste form and non-metallic waste form(s) acceptable for repository disposal, treatment and storage of secondary waste, which may include hardware, filters and failed equipment Facilities to manage waste previous to final disposal—including decay heat cooling of high-level waste before disposal Interim storage of products For multi-objective fuel cycles, there may be incentives to separate a number of materials given their potential benefit as shown in Figure E.1 for LWR fuel. As more products are recovered, the need to use a variety of separation and product fabrication technologies increases. Examples of different recycling technologies and their development stages are shown in Table E.2 for metal and oxide fuels. Figure e.1 potential product and Waste Streams of lWr Fuel recycling Fission Gases 3 H, 85 Kr, 129 I, 14 CO 2 ) (Driven by Regulatory Requirements) Actinide Recovery (Driven by Recycling Reactor Choice) Pure uranium u/Pu, u/Pu/np or u/Tru am/cm, am/cm/np or am Spent Nuclear Fuel Tailored HLW Waste Forms (Driven by Waste Management) Tc l cs/Sr Waste Water 3 H, 129 I) (Driven by Regulatory Requirements) Process Wastes (Driven by Regulatory Requirements) residual Fission Products 232 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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SenSitivity analySiS: alternative a
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Fast reactor technical Characterist
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cooled fast reactor (SFR) fueled by
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Summary oF ConCluSionS Among the in
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[hoffman et al., 2006] e.a. hoffman
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This chapter reports the cost of th
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Table 7.1 Input Parameter Assumptio
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Twice-Through Cycle Table 7.3 shows
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Table 7.4 The LCOE for the Fast Rea
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higher cost of disposal of the spen
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110 MIT STudy on The FuTure oF nucl
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power program might be used, as is
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Figure 8.1 Weapons-usability Charac
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inStitutional approaCheS to Fuel Cy
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the iaea additional protocol an Iae
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in technology innovation are likely
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Reprocessing choices Commercial rep
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Table 8.2 Safeguard Technical Objec
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port for nuclear power over the per
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Those Americans who have an opinion
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who are very concerned with global
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p Waste management must be integrat
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options because we do not know toda
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Nuclear Security. Nonproliferation
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There have been major changes in ou
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There are large financial and polic
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Figure 3A.2 shows the results. As c
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Figure A.3 plots Eq (2), where adva
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Again, assuming that q = 0.29, the
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Note that Eq. [7] suggests employin
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Figure 3b.1 Cumulative probability
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Figure 5a.1 decay of radioactivity
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and 241 Am. For the short term, hea
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Repository Engineering All reposito
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epreSentative repoSitory deSiGnS: u
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orehole diSpoSal There are three me
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table 7a.1 list of variables , 1 lc
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The Twice-Through Cycle The LCOE fo
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A proper representation of the chai
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In the Twice-Through Cycle, the pai
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table 7a.2 once-through Fuel Cycle
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above ground storage. However, the
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Page 201 and 202: p Analogous to plutonium. Plutonium
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