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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Appendix E: Fuel Cycle Characteristics and Geologic Repository Metrics of Advanced Nuclear Reactors
Appendix E: Fuel Cycle Characteristics and Geologic Repository Metrics of Advanced Nuclear Reactors
Pages 275-286
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From page 275... ...
, resulting in efficient slowing down or moderation of neutrons to arrive at an average neutron energy of 0.25 eV. Thus, water serves both as a coolant and moderator in light water reactors (LWRs)
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From page 276... ...
. Neutron reaction cross sections representing neutron/nucleus reaction probabilities -- in particular, fission cross section and radiative capture cross section -- depend heavily on the energy of neutrons and hence the neutron flux spectrum, as well as on the type of nuclides with which the neutrons interact.
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From page 277... ...
modular LWR, as summarized in Table E.2. TABLE E.2 Key Attributes of Advanced Nuclear Reactors Under Development Project Description Power Features Fuel Cycle Base Case: Large Light Water Reactor AP1000 Reactor 3.4 GWt Pressurized water coolant LEU once-through Westinghouse Electric 1.09 GWe 15.5 MPa 49 MWd/kgHM Modular Light Water Reactor NuScale Small 250 MWt Natural circulation cooling LEU once-through Modular Reactor 77 MWe 12 PWR modules 41-60 MWd/kgHM Fast-Spectrum Reactor Versatile Test Reactor 300 MWt Na cooled U-20Pu-10Zr metallic fuel U.S.
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From page 278... ...
NOTE: CANDU = Canadian Deuterium Uranium; FHR = fluoride-cooled high-temperature reactor; GWt = gigawatt thermal; GWe = gigawatt electric; HALEU = high assay low-enriched uranium; HTGR = high-temperature gas-cooled reactor; LEU = low-enriched uranium; LFTR = liquid fluoride thorium reactor; MPa = megapascal; MWd/kgHM = megawatt-day per kilogram of heavy metal; MWe = megawatt electric; MWt = megawatt thermal; PWR = pressurized water reactor; TRISO = TRistructural ISOtropic. MATERIAL FLOW SHEETS FOR REPRESENTATIVE FUEL CYCLES The corresponding fuel cycle characteristics are also discussed in terms of the inventories of nuclear fuel material, referred to as "heavy metal" (HM)
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From page 279... ...
Several modular LWR plants under development, including the NuScale Small Modular Reactor, feature low-enrichment uranium oxide fuel similar to that used in LWR plants and fuel cycle characteristics will not change much from those of Figure E.2, subject to possible improvements with increased thermal efficiency. Sodium-Cooled Fast Reactor The SFR design features one of the key Generation IV reactors fueled with uranium and TRU elements in the form of metallic U-Zr or U-Pu-Zr fuel rods.
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From page 280... ...
TerraPower plans to complete the development of fuel element designs without sodium bonding for the Type 1B Metal Core. With an increased thermal efficiency, the Natrium core design, as a fast-spectrum reactor, indicates a three-fold increase in the discharge fuel burnup and a four-fold reduction in the used nuclear fuel inventory discharged, compared with an equivalent 1.0-GWe LWR plant.
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From page 281... ...
The fuel residence time of 76.5 years is estimated from the limited recycle MSR case, represented as Evaluation Group 10, and essentially indicates that the fuel salt circulates through the system indefinitely, resulting in a large fuel burnup. The MSR system provides a continuous online fuel salt treatment with low processing loss so that the material processed and discharged consists primarily of FPs produced during the reactor operation.
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From page 282... ...
COMPARISON OF MATERIAL FLOW AND REPOSITORY METRICS The charge and discharge fuel material flows illustrated in Figures E.2–E.6 are summarized in Table E.3 and compared to clarify the characteristics of the five fuel cycles chosen to represent advanced reactor designs evaluated. The repository metrics including radioactivity at 100 and 100,000 years are compared for the three advanced reactor designs, together with the reference PWR and two-tier SFR-PWR recycle system.
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From page 283... ...
(The FP inventories are reduced for designs with higher thermal efficiency.) The yields for short- and long-lived FPs of interest in used fuel management and geologic repository analysis depend somewhat on the neutron flux spectrum and fissile nuclides, but the sum of FP yields of interest appear nearly independent of the fuel cycle.1 Table E.3 summarizes the results of spent nuclear fuel and high-level waste (HLW)
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From page 284... ...
a Excludes contributions from isometric. NOTE: HALEU = high-assay low-enriched uranium; LEU = low-enriched uranium; NFCE&S = nuclear fuel cycle evaluation and screening; PWR = pressurized water reactor; SFR = sodium-cooled fast reactor; TRISO = TRistructural ISOtropic.
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From page 285... ...
16 225Ra 14 210Po 35 93Zr 38 126Sn 16 225Ac 14 210Bi 35 93Nb* 37 210Po 11 214Po 35 233Pa 27 214Po 11 230Th 35 237Np 27 222Rn 11 135Cs 15 135Cs 17 233U 13 NOTE: HTGR = high-temperature gas-cooled reactor; MSR = molten salt reactor; PWR = pressurized water reactor; SFR = sodium-cooled fast reactor; *
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From page 286... ...
The production of MAs is significantly smaller in the SFR than in the PWR. These observations translate to a key potential of the SFR serving as a breeder of fissile Pu with a minor negative impact due to tracer quantities of MAs in the recycled fuel.
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