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4 Fuel Cycle Development for Advanced Nuclear Reactors
Pages 83-138

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From page 83...
... Finally, Section 4.5 provides information relevant for safety considerations of fuel cycles. 1  In contrast, Chapter 5 focuses on the direct disposal of spent nuclear fuel as waste.
From page 84...
... The situ ation is still in flux, with great uncertainty surrounding potential sanctions on Russian uranium and larger disruptions to the nuclear supply chain, but the committee provides here several recent announcements that could impact the development of advanced reactors and fuel cycles in the United States. Two advanced reactor developers gave public statements to Wired magazine in March 2022 that they would not use Russian HALEU for their reactors, despite having previously planned to do so.
From page 85...
... Implementing advanced fast reactors and their associated fuel cycles in order to effectively reduce, but not eliminate (because of inevitable process loss) , the quantity of long-lived actinides destined for geologic disposal would have to be operated for many decades to achieve the permanent benefits to the repository and other parts of the nuclear fuel cycle.
From page 86...
... Specifically, DOE should develop and implement a phased, long-range research and development program that focuses on advanced separations and transmutations technologies. Finding 9: As proposed for some advanced reactor closed fuel cycles, reprocessing and recycling of spent nuclear fuel introduces additional safety and environmental considerations over the management of open-cycle light water reactor oxide fuels.
From page 87...
... and international capacities for the specific steps of the front end: mining and milling, conversion, enrichment, and fuel fabrication, with particular emphasis on addressing the challenges of supplying HALEU. 4.2.1 Mining and Milling As introduced in Chapter 2, the mining and milling of uranium provide the raw uranium material required for nuclear fuel.
From page 88...
... The U.S. government has ongoing efforts to develop HALEU production capability through enrichment of natural uranium, downblending of highly enriched uranium excess to nuclear weapons, and reprocessing and downblending of highly enriched uranium spent nuclear fuel from research and test reactors.
From page 89...
... In addition, the site could produce even greater amounts of HALEU: in particular, up to 19 MT from reprocessing DOE's aluminum-based spent nuclear fuel, which is stored at the site, and up to 13 MT from reprocessing Idaho National Laboratory's spent nuclear fuel. Production of 1 to 1.5 MT per year could start in FY2023 (Bates, 2020)
From page 90...
... The cost estimate for fabrication equipment and glove boxes totaled $22.5 million for the metallic fuel line and $28 million for the ceramic/ intermetallic fuel fabrication line, with uncertainties of −20 to +50 percent. The annual operating cost for a fuel fabrication line was estimated to be around $7 million in 2019 dollars.
From page 91...
... sanctions on importation of Russian nuclear fuel services. Potentially, Orano could also produce and supply HALEU, though its enrichment facilities in France are not currently configured for this purpose.
From page 92...
... However, the existing domestic fuel fabrication facilities are not equipped to handle HALEU or to produce non–uranium dioxide fuels. Thus, fuel fabrication capabilities will have to be built to meet the needs of advanced reactors requiring HALEU and/or using fuel types other than uranium dioxide.
From page 93...
... NRC and fabricate low-enriched uranium fuel that is sold worldwide to the LWR community: Global Nuclear FuelAmericas in Wilmington, North Carolina; Westinghouse Columbia Fuel Fabrication Facility in Columbia, South Carolina; and Framatome, Inc., in Richland, Washington. In addition, as noted in Section 4.2.3, two U.S.
From page 94...
... . Current TRISO fuel particle designs use a spherical kernel with a diameter of 350–500 microns, which contains the nuclear fuel (e.g., uranium dioxide or UCO, a mixture of uranium oxide and uranium carbide)
From page 95...
... Most of the work to date has been processing with depleted and natural uranium, but the processing area is authorized to handle research quantities of HALEU to support fuel design, manufacturing, and licensing for the Xe-100 reactor. The facility is referred to as a "pilot facility" because only one fuel fabrication production line is being developed and tested under the American Society of Mechanical Engineers' Nuclear Qualification Assurance Standard.
From page 96...
... Fabrication of metallic fuels, as outlined in Figure 4.3, involves (1) preparing the fuel feedstock from ore or spent nuclear fuel; (2)
From page 97...
... , part of DOE's Nuclear Fuel Cycle and Supply Chain Program, is focusing its efforts related to advanced reactor fuel development on metallic fuels, given their proposed use in several advanced reactor designs (INL, 2021b)
From page 98...
... 4.3 BACK END OF THE FUEL CYCLE The remainder of this chapter discusses fuel cycles that support, or conceptually could support, the existing LWR fleet and potential future advanced reactors starting with the reference case, the once-through fuel cycle. The introduction of fuel reprocessing in a few countries has resulted in the monorecycling of both uranium and plutonium in existing LWRs.
From page 99...
... In its 2010 report Advanced Nuclear Fuel Cycles -- Main Challenges and Strategic Choices, the Electric Power Research Institute (EPRI) defined open, partially closed, and fully closed fuel cycles with respect to the management of Pu, noting that these terms are "often associated with different understandings by different authors" (EPRI, 2010b)
From page 100...
... The simplest and most straightforward fuel cycle is the once-through cycle that uses low-enriched uranium in LWRs and directly disposes of the spent nuclear fuel in a deep geologic repository. The once-through cycle, shown in Figure 4.4, is an open fuel cycle and is the reference to which all other fuel cycles are compared.
From page 101...
... The nitric acid solution is designated as high-level waste and is further treated to immobilize the minor actinides and nonvolatile fission products in a glass matrix using vitrification. In the vitrification process, the radioactive materials are dispersed within the glass and chemically bonded in the glass network.
From page 102...
... . Implementing a fuel cycle for the monorecycle of Pu requires the addition of a MOX fuel fabrication facility to the supporting infrastructure.
From page 103...
... LWR MOX Geologic Repository Pu HLW-Vitrified glass LWR-MOX Spent Fuel (FPs and MAs) Fuel Fabrication Reprocessing U dep Storage FIGURE 4.6 Steps for monorecycling Pu fuel in LWRs.
From page 104...
... . Many of these isotopes, especially californium-252, are intense neutron emitters that would make reprocessing or fuel fabrication much more difficult -- "the neutron source term for multi-pass recycling of MAs in LWRs is more than 2,000 times higher than that for fast reactors" (EPRI, 2010b)
From page 105...
... Closing the fuel cycle to recycle plutonium and destroy the minor actinides requires the development of advanced separation processes and fuel fabrication technologies. Fully closing the fuel cycle would require processing of advanced fuels that are much more radioactive than conventional uranium oxide fuel.
From page 106...
... . To achieve a 100-fold reduction in long-term hazards associated with spent nuclear fuel, fuel burnup in advanced reactors would need to be high, and reprocessing and fuel fabrication processes would have to be demonstrated on an industrial scale to have high recovery efficiencies with minimal (<0.1 percent)
From page 107...
... Consequently, any attempt to manage the minor actinides -- that is, to reduce their mass for disposal in a geologic repository -- only makes sense in the framework of closed fuel cycles with fast reactors (Szieberth et al., 2013; Tuček et al., 2008)
From page 108...
... For the case of plutonium breeding and P&T of the minor actinides in fast reactors, the same fuel cycle strategy as shown in Figure 4.9 is employed, except that the fast reactor is operating as a breeder/converter with a CR ≥1 and uses MOX fuel. The MOX fuel for the fast breeder/converter reactor (FBR-MOX)
From page 109...
... Thus, loading minor actinides using this method will likely be constrained to no more than a few percent. This constraint also helps to limit the dose and decay heat that must be managed during fuel fabrication, transport, and handling.
From page 110...
... The downside TABLE 4.1 Impact of Partioning and Transmutation of Minor Actinides on Fuel Fabrication and Reprocessing Actinide Content of FR Fuel " (comparison with reference FR-MOX fuel) 2.5% Np 2.5% Am 2.5% Cm Decay heat ×1 ×4 × 12 Fuel Fabrication γ dose ×4 × 80 × 500 Neutron source ×1 ×2 × 1,700 Decay heat ×2 ×3 ×6 Reprocessing γ dose ×1 ×1 ×1 Neutron source ×1 ×4 ×8 NOTE: FR = fast reactor; MOX = mixed oxide.
From page 111...
... Plutonium and the minor actinides are produced in nuclear fuel under irradiation in either thermal or fast neutron spectra, and the buildup of each isotope is a strong function of burnup. As a result, spent nuclear fuel subjected to different burnup conditions can result in large isotopic variations (i.e., large differences in the ratios of isotopes of plutonium, neptunium, americium, and curium)
From page 112...
... Head-end processes for liquid-fueled or liquid-cooled molten salt reactors differ in that they are used to prepare the spent nuclear fuel for subsequent use in molten salt reactors. Depending on the specific reactor type, fluorination or chlorination is used to convert spent oxide fuels to either fluoride or chloride salts.
From page 113...
... 4.3.6.2 Advanced Reprocessing Strategies for Nonaqueous, Pyroprocessing-Based Partitioning of the Actinides Nonaqueous, or pyroelectrochemical, processes used for recycling spent nuclear fuel rely on refining techniques23 conducted in molten chloride (or fluoride) salts at elevated temperatures (500–900°C)
From page 114...
... Motivation U-only U GANEX (1st cycle) , NEXT Recover remaining fissile U for UREX possible reenrichment Major actinide U and Pu separately PUREX -- Industry standard Recover fissile U for reenrichment and corecovery Pu for recycle as MOX fuel U/Pu or Pu/Np as a group COEX, UREX, UREX+ Aid MOX fuel fabrication and recycle U/Pu/Np as a group TBP extraction in NEXT process U/Pu/Np mixed oxide fuel recycle, send Am/Cm to waste with lanthanides and other fission products Transuranic Pu/Np/Am/Cm GANEX (2nd Cycle)
From page 115...
... The driving force for the separations is the free energy of formation (ΔG  º ) of f the various metal chlorides in the spent nuclear fuel.
From page 116...
... . Efforts to pyroprocess sodium-bonded highly enriched uranium metallic fuel from both EBR-II and Fast Flux Test Facility (FFTF)
From page 117...
... Collocation also avoids some of the transportation issues for spent nuclear fuel, and existing physical protection systems and engineered safeguards can be leveraged across the entire plant site. From a nonproliferation viewpoint, collocation of spent nuclear fuel storage, reprocessing, and fabrication of recycled fuel -- all within one protected facility -- is thought to be a more effective safeguards strategy compared with performing partial separation of actinides and fission products (using, e.g., UREX and COEXTM)
From page 118...
... In that case, a more extensive actinide drawdown operation by electrolysis or chemical reduction before passing the process salt on to waste form production steps would be needed to minimize actinide losses.35 4.3.6.5 Molten Salt Reactor: An Obvious Application of Pyroelectrometallurgical Technology Liquid-fueled and liquid-cooled MSRs are unique in that the molten salt acts as both the fuel and the heat transfer fluid, and the reactors are adaptable to a wide range of fuel cycles (Hombourger et al., 2019)
From page 119...
... However, it is too soon in the development of MSRs to discuss and analyze their associated fuel cycles. If and when MSR designs become more mature, their associated fuel cycles will become more obvious, as they will depend on the objectives of reactor operation (e.g., power production, breeder with online salt processing, actinide burning)
From page 120...
... , shows several potential fuel cycles and their expected impact on natural uranium consumption and on the mass of TRU waste being eventually disposed of in a geologic repository. Five fuel cycles were selected for illustration in Table 4.3:
From page 121...
... • LWR + FR (fast reactor) -- Multirecycling of plutonium in an FR in the form of MOX-FR, with partitioning of americium and curium, once-through transmutation of americium, and 100-year storage of curium • FR -- Multirecycling of plutonium in the form of MOX-FR with partitioning and homogeneous transmutation of transuranic elements These fuel cycles were selected first on the basis of their improved plutonium management in LWRs and second on their management of minor actinides (neptunium, americium, and curium)
From page 122...
... [kg] Pu 767 3,285 4,818 10,293 17,520 Np 53 131 116 241 88 Am 22 88 307 438 701 Cm 11 44 158 263 175 Total TRU 853 3,548 5,399 11,235 18,484 Requirements for Advanced Reactors and Facilities Fast reactors and Fast reactors and ALWRsb None required None required advanced FBR fuel advanced FBR fuel and reprocessing c reprocessing reprocessing a Values in this table were derived from the information in (NEA-OECD, 2006b)
From page 123...
... Whereas closing the fuel cycle makes recycling fuel (i.e., reprocessing and fuel fabrication) much more difficult, removing the actinides, which includes uranium, from the waste stream makes handling and managing of the waste in a repository somewhat easier and less complicated, because only about 3 percent of the mass of the spent nuclear fuel, consisting of the fission products, goes to the repository.
From page 124...
... Additionally, one must consider the radiotoxicity of the decay products. Thus, although some fuel cycles lower the actinide inventory, this does not necessarily reduce the long-term hazard.
From page 125...
... . As seen from Figure 4.12, the radiotoxicity of spent nuclear fuel in a geologic repository will remain above the reference level for (1)
From page 126...
... The residual heat power associated with spent nuclear fuel follows essentially the same trend as radioactive decay, being driven by short-lived fission products for the first 50–70 years and then by the alpha-emitting actinides (Pu, then minor actinides) at later times.
From page 127...
... , not the waste volume, is a key factor in repository design, a properly designed repository will have a disposal density (canister spacing) that manages the thermal pulse from the fission products from spent nuclear fuel, and doing so should be well within a conservative envelope to handle the late thermal load from the actinides.
From page 128...
... However, this option hinges on the siting, construction, and operation of a geologic repository. 4.4 COST ESTIMATION OF DIFFERENT FUEL CYCLE OPTIONS The committee was tasked with examining the potential costs of the different nuclear fuel cycles required for advanced nuclear reactors that could be commercially deployed by 2050.
From page 129...
... Second, there is great uncertainty about the cost of reprocessing spent fuel and the cost of fabricating the recycled fuel. Third, there is enormous uncertainty about the construction and operating costs for fast reactors, which are at the core of many alternative fuel cycles." Furthermore, the MIT study cautions: "A second elusive factor that can play a large role in the economic calculations is the cost of capital (discount rate)
From page 130...
... and the canceled mixed oxide fuel fabrication facility at the Savannah River Site. Chapter 5 also provides information on the additional costs to the government when there are delays in opening geologic waste repositories; for example, about $600 million annually is being paid out of the Judgment Fund to utilities for costs of continued storage of spent nuclear fuel at nuclear power plant sites, since they cannot be stored at a disposal facility.
From page 131...
... To gain some insights regarding costs, the committee took a graded approach that reflected the reactor choices and fuel cycle options provided by the advanced reactor developers interviewed by the committee. Most of the nonwater-cooled advanced reactor developers expressed plans to use a once-through fuel cycle combined with direct geologic disposal for the foreseeable future with the option of transitioning to a closed fuel cycle at a later time; only a few advanced reactors expressed plans to close their fuel cycles upon initial deployment.
From page 132...
... The cost of fuel cycles to support advanced fast reactors or molten salt reactors will be specific to the reactor technology and will potentially exceed several tens of billions of dollars as the number of deployed reactor designs increases. During this study, the committee recognized the important concept of trade-offs when assessing potential merits and viabilities of different advanced reactors and their fuels and fuel cycles.
From page 133...
... As discussed in Chapters 2 and 5, the lack of a geologic repository requires that spent nuclear fuel be stored at reactor sites throughout the country. The spent fuels currently being stored are chemically stable and maintain the fission products and actinides in a nondispersible form.
From page 134...
... and external flooding. 4.5.2.2 Safety Considerations for Fuel Processing On the back end of the fuel cycle, spent nuclear fuel processing introduces risk associated with complex industrial chemical or electrochemical processes that involve treating significant quantities of fissile material with large quantities of other hazardous material.
From page 135...
... . Because of the risks associated with processing spent nuclear fuel, a graded approach to defense in depth45 is applied to processing facilities, similar to that applied to the nuclear power plants they support (IAEA, 2017b)
From page 136...
... For example, while reprocessing reduces the inventory of radioactive and fissile material ultimately disposed in a geologic repository, it requires managing large inventories of these materials at processing facilities, as illustrated in Table 4.4. In addition to the risks associated with the processing of spent nuclear fuel, processing facilities will also serve as interim storage locations for spent nuclear fuel awaiting processing and for the storage of low- and high-level radioactive wastes resulting from reprocessing.
From page 137...
... Tritium releases from processing are comparable to those from a single nuclear power plant. TABLE 4.4 Comparison of Radioactive Material Release Limits to Typical Discharges at the La Hague Reprocessing Facility and a Typical U.S.


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