Merits and Viability of Different Nuclear Fuel Cycles and Technology Options and the Waste Aspects of Advanced Nuclear Reactors (2023) / Chapter Skim
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3 Potential Merits and Viability of Advanced Nuclear Reactors and Associated Fuel Cycles
3 Potential Merits and Viability of Advanced Nuclear Reactors and Associated Fuel Cycles
Pages 53-82
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From page 53... ...
(Chapter 4 provides more details on the development and infrastructure needed to support fuel cycles for advanced reactors.) The committee notes that an assessment of the cost competitiveness of advanced reactor systems as compared with other energy sources is beyond the scope of this study.
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DOE-NE has programs that support the development of the advanced reactor and associated fuel cycles, but it will have to make difficult decisions in the coming years based on budgetary constraints. Finally, while the advanced reactors under development have several potential merits, these have yet to be demonstrated, and there are no operating prototypes in the United States for any of these reactors.
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comparable to uranium-based fuels. 3.2 TYPES OF ADVANCED REACTORS AND ASSOCIATED FUEL CYCLES A large number of advanced reactors are being designed that differ significantly from the current fleet of thermal LWRs deployed in the United States.
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. DOE's framework for advanced reactors designs is similar to that of GIF, but DOE more highly prioritizes versatility compared with earlier reactor generations, especially the ability to provide nonelectrical services, such as desalination, process heat, and hydrogen production, as an additional goal of the advanced reactor designs.
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ADVANCED NUCLEAR REACTORS AND ASSOCIATED FUEL CYCLES 57 FIGURE 3.1 Schematics of the six advanced reactor concepts in the Generation IV International Forum.
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As discussed in Section 3.5, cooperative activities involve use of materials testing reactors and other facilities for evaluation of advanced reactors' fuels and materials. To facilitate cooperation, INEPC can use bilateral technical collaboration arrangements, memorandums of understanding, technical action plans, the International Nuclear Energy Research Initiative (I-NERI)
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. Detailed technical design considerations, safety aspects, electricity generation, and nonelectricity applications of these advanced reactors are addressed in the parallel National Academies study Laying the Foundation for New and Advanced Nuclear Reactors.
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U/Steel HALEU OTC Once-through breed reactor (10–18.5% core and burn; closed fuel average) cycle via multirecycling ARC-100 U-Zr/Steel HALEU (10.9- OTC Closed fuel cycle via 15.5%)
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UC/TRISO/ HALEU (19.75%) OTC prismatic block a Primary fuel cycle as intended currently by the advanced reactor developers.
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. In the United States, as discussed in detail in Section 3.3.2, X-energy's Xe-100 has recently received more than $1 billion of support via DOE's Advanced Reactor Demonstration Program (ARDP)
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. According to the IAEA ARIS (Advanced Reactors Information System)
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. 3.2.3.4 Lead-Cooled Fast Reactor Lead-cooled fast reactors (LFRs)
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or dissolved in the molten salt to form a liquid "fuel salt" such as in Flibe Energy's design. The latter has the advantage that no solid fuel fabrication is required, but because gaseous fission products separate from the liquid fuel during operations, a fully open fuel cycle is not technically possible.13 Molten salt coolants can be either a fluoride- (e.g., FLiBe [27LiF-BeF2]
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Research needs for FHR fuel cycles are analogous to those described above for both TRISO fuel and molten salts, and are detailed in Chapters 4 and 5. Kairos Power is developing an example of this reactor type, the KP-FHR.
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use of uranium dioxide fuel with enrichment less than 5 percent uranium-235, which can be produced with the existing LWR fuel cycle infrastructure; (3) substantial financial support from government and investors; and (4)
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. 3.2.4 Fuel Cycle Options for Advanced Reactors During the information-gathering meetings, almost all developers told the committee that they are planning on an open, once-through fuel cycle at least for the near to intermediate terms, and likely for the next 30 years (see Table 3.1)
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Fully implementing a fuel cycle, however, could require a couple of decades to a century in order to transition from a fleet using one fuel cycle, such as the once-through LWR cycle, to a fleet of fast reactors using multirecycling (Williamson and Taiwo, 2021)
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Comparing all values for η suggests that the most promising breeding occurs with a fast reactor and 239Pu (i.e., a U-based fuel cycle)
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and summarized here. If the fuel is reprocessed from a thermal reactor operating on a Th/U fuel cycle, mining of U for 235U can be eliminated, thus extending nuclear fuel resources by two orders of magnitude without the need to deploy fast reactors.
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. However, the development, licensing, and construction of advanced reactor systems that might realize the full benefit of a closed Th/U fuel cycle is a long-term undertaking, as the requisite dedicated Gen IV and beyond breeder reactors, including molten salt reactors, are currently in the conceptual design phase.
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A report by the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development on Th fuel cycles highlights several long-lived radionuclides generated in Th fuel cycles -- 233U, 231Pa, and 232U -- that "have a more important radiotoxicity than their counterparts in the uranium cycle," and also concludes that "radiotoxicity of thorium-based fuels is more accurately described as being comparable to that of uranium-based spent nuclear fuel" (NEA-OECD, 2015b)
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3.3 U.S. GOVERNMENT SUPPORT FOR DEVELOPMENT OF ADVANCED REACTORS AND ASSOCIATED FUEL CYCLES Chapter 2 provides information on U.S.
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• By 2035, demonstrate at least two additional advanced reactor designs through partnerships with industry." For developing advanced nuclear fuel cycles, the goal is to attain these objectives: • "Address gaps in the domestic nuclear fuel supply chain. • Address gaps in the domestic nuclear fuel cycle for advanced reactors.
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In October 2020, DOE-NE announced the selection of TerraPower and X-energy as the Advanced Reactor Demonstration award winners for demonstration of the Natrium and Xe-100 reactor designs, respectively. On December 16, 2020, DOE announced the selections of five teams to receive funding under the Risk Reduction for Future Demonstration program: Kairos Power, LLC, for the Hermes Reduced-Scale Test Reactor; Westinghouse Electric Company, LLC, for the eVinci microreactor; BWXT Advanced Technologies, LLC, for the BWXT Advanced Nuclear Reactor; Holtec Government Services, LLC, for the Holtec SMR-160 Reactor; and Southern Company Services, Inc., for the Molten Chloride Reactor Experiment.
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program provides "access to technical, regulatory, and financial support" for nuclear energy developers, both existing commercial reactor technologies and advanced reactors (Caponiti, 2020b)
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3.3.4 U.S. Nuclear Regulatory Commission's Regulatory Programs on Advanced Reactors and Associated Fuel Cycles As mentioned above, NEIMA directs the U.S.
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NRC staff on the regulatory programs relevant for advanced reactors and associated fuel cycles (Regan et al., 2020)
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Notably, advanced reactors, which propose using a wider variety of coolants and fuel types, will have more comprehensive prototyping requirements. In addition to the prototyping described above, advanced reactor developers will have to do substantial prototyping of basic materials' strength and performance when subjected to entirely different operating environments, including differing coolants, neutron flux, temperature, and pressures.
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This weakening in active test reactors, new build expertise, and manufacturing at a commercial level will impact how quickly technology development for advanced reactors and fuel cycles can advance in the United States, especially without considering foreign supply chain expertise. As mentioned in Section 3.3.2, a major question for development and deployment of test reactors is, Who should pay for the reactors?
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. While the ATR has capabilities relevant for testing some types of advanced reactors, the major missing capability is fast neutrons.
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