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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6 Nonproliferation Implications and Security Risks
6 Nonproliferation Implications and Security Risks
Pages 181-216
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From page 181... ...
As discussed in Chapter 4, most advanced reactor designs propose using HALEU fuel, which, given 1 Nuclear proliferation is defined as diversion or misuse of civil nuclear materials by a state to produce nuclear weapons. 2 Nuclear terrorism is defined as acquisition of nuclear materials by substate actors seeking to build improvised nuclear explosive devices.
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From page 182... ...
Nonetheless, safeguards obligations on domestic facilities that the United States could assume under its voluntary offer agreement with the International Atomic Energy Agency (IAEA) would have indirect benefits by providing test beds for IAEA safeguards approaches for new technologies that may be deployed in other countries and would set an example for international cooperation.
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From page 183... ...
and other attractive nuclear materials that may be present in advanced reactor fuel cycles. 6.2 BACKGROUND ON NONPROLIFERATION, NUCLEAR MATERIAL SAFEGUARDS, AND NUCLEAR SECURITY 6.2.1 Nuclear Nonproliferation The Treaty on the Non-Proliferation of Nuclear Weapons (NPT)
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From page 184... ...
BOX 6.1 Definitions Relevant for Nuclear Nonproliferation and Safeguards Nuclear material accountancy is "implemented by the facility operator and the State system of accounting for and control of nuclear material (SSAC) … to satisfy the requirements in the safeguards agreement between the IAEA [International Atomic Energy Agency]
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From page 185... ...
of special nuclear materials indicates "the approximate amount of nuclear material for which the possibility of manufacturing a nuclear explosive device cannot be excluded." Significant quantities also take into account unavoidable losses from conversion and manufacturing processes and should not be confused with critical masses. "Significant quantities are used in establishing the quantity component of the IAEA inspection goal" (1 SQ or more of nuclear material over a material balance period)
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From page 186... ...
BOX 6.2 Implementation of IAEA Safeguards at U.S. Advanced Reactor and Fuel Cycle Facilities As mentioned in Section 6.2.2, as a nuclear weapon state under the Treaty on the Non-Proliferation of Nuclear Weapons, the United States is not obligated to make all its nuclear materials and facilities available for verification by the International Atomic Energy Agency (IAEA)
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From page 187... ...
Early involvement by the IAEA in the advanced reactor and fuel cycle projects would promote the effective implementation of safeguards-by-design principles. To the extent possible, these efforts would be comprehensive and serve as models for full IAEA verification protocols in non–nuclear weapon states where advanced reactors and fuel cycle facilities may be exported.
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From page 188... ...
As discussed in Chapter 5, advanced reactors and fuel cycles will create unique secondary wastes not associated with spent fuel, but these wastes are not expected to need physical protection controls beyond the current guidance provided for in existing IAEA documents. In December 2018, the IAEA convened a group of external experts to review the existing physical security documents in the context of advanced reactors.
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From page 189... ...
The U.S. NRC uses a nuclear material categorization system similar to that of the IAEA for grading the security requirements for protection against theft based on the attractiveness of the material for nuclear weapons.
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From page 190... ...
From an international nuclear security perspective, the IAEA provides umbrella guidance of how member states can comply with their CPPNM obligations regarding physical protection of nuclear and radiological materials in transport. Spent fuel security requirements for U.S.
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From page 191... ...
Relevant for this report are the NNSA objectives of "prevent" and "counter": • "Prevent would-be proliferant states from developing nuclear weapons or acquiring weapons-usable nuclear material, equipment, technology, and expertise, and prevent non-state actors from acquiring nuclear and radioactive materials that can be used for malicious purposes"; and • "Counter the efforts of both would-be proliferant states and non-state actors to acquire, develop, disseminate, deliver, or use the materials, expertise, or components of a nuclear or radiological device." (DOE-NNSA, n.d.-b) While most of the advanced reactor and fuel cycle facilities will be regulated by the U.S.
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From page 192... ...
6.2.5 Nuclear Material Attractiveness An important metric for assessing the relative nuclear proliferation and nuclear terrorism risks posed by different nuclear fuel cycles is the "attractiveness" of the various nuclear materials within the fuel cycle for different adversaries seeking to acquire nuclear weapons. The material attractiveness of a specific type of nuclear material can be defined as its "relative utility … for an adversary in constructing a nuclear device" (Bathke, 2021)
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From page 193... ...
. These materials are particularly relevant for proliferation and terrorism risks in those advanced reactor fuel cycles that separate them in quantities of significance from spent fuel, either individually or in mixtures (see Chapter 4)
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From page 194... ...
6.3 EVALUATION OF NONPROLIFERATION IMPLICATIONS AND SECURITY RISKS OF ADVANCED REACTORS' FUELS AND FUEL CYCLES This section provides the committee's evaluation of nonproliferation and security risks regarding the aspects identified in the statement of task (see Sidebar 1.1 in Chapter 1) for the fuel cycles of advanced reactor types examined in this study.
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From page 195... ...
Such an analysis would fully consider material attractiveness and proliferation resistance features, all routes to acquisition of nuclear weapon-usable materials, and the broader technical capabilities and political context in the countries where these fuel cycles may be deployed. 6.3.1 Once-Through Fast Reactors Using HALEU This category includes the Natrium and ARC-100 reactors (by TerraPower and ARC Clean Technology, respectively)
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From page 196... ...
Also, there will be a one assembly in, one assembly out restriction on the fuel handling machine, which will also have the capability to read and display the assembly tags that can be easily monitored. After the spent fuel is transferred to the water-filled pool and eventually to dry storage, the IAEA could use safeguards approaches it has experience implementing, such as the containment and surveillance measures it applied at the spent fuel pools at the Joyo and Monju sodium-cooled fast reactors in Japan, where both fresh and spent fuel assemblies were stored (Bays et al., 2021)
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From page 197... ...
. 6.3.1.3 Metallic Fuel Fabrication Another aspect of the fuel cycle for the PRISM-type metal-fueled fast reactors relevant for safeguards is that current fuel fabrication methods generate a large quantity of unrecoverable scrap (nearly 30 percent)
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From page 198... ...
.15 This material accountancy challenge is partially offset by the large number of items that would need to be diverted to acquire a significant quantity of special nuclear material. For example, each Xe-100 fresh fuel pebble contains 7 g of HALEU, so approximately 69,000 pebbles would need to be diverted to acquire 1 SQ of lowenriched uranium (485 kg)
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From page 199... ...
and have the same number of spent fuel pebbles to store and ultimately dispose of at the end of plant life. In that context, the likelihood of timely detection of a diversion of 1 SQ may be lower than one might surmise based on the large number of items needed, and will decrease over time as spent fuel pebbles accumulate.
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From page 200... ...
, all isotopic mixtures of plutonium, except those with 80 percent or more plutonium-238, may be attractive to some degree for nuclear weapons. A second argument is that TRISO fuel is inherently proliferation resistant because it is difficult to reprocess and there is little experience with the chemical techniques that would be required to do so, in comparison with highly mature LWR fuel reprocessing.
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From page 201... ...
. No research facilities are currently conducting experiments on irradiated salts in the United States, although China has recently begun to operate a small molten salt test reactor (Mallapaty, 2021; Scott et al., 2021; WNN, 2022b)
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From page 202... ...
. Establishing an effective material accountancy approach in salt-fueled reactors will be a complicated endeavor, requiring measurement of the types and quantities of nuclear materials in the fresh fuel, irradiated fuel, process stream, and waste streams.
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From page 203... ...
The committee did not receive sufficient information about the fuel cycle for this reactor to perform a detailed assessment. 6.3.4 Nonproliferation and Security Implications of the Use of HALEU Nearly all of the advanced reactor designs currently being supported by DOE and private entities would require HALEU in the enrichment range of 13–19.75 percent, but the fuel cycle supporting commercial nuclear power production today is not designed or optimized to accommodate reactors requiring HALEU fuel.
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From page 204... ...
whether the large-scale deployment of HALEU-fueled reactors and associated fuel cycle facilities around the world could lead to a significant increase in nuclear proliferation and nuclear terrorism risks compared with the current LWR-dominated fleet; (2) what measures would be needed to adequately mitigate those risks; and (3)
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From page 205... ...
In particular, facilities possessing a Category I quantity of highly enriched uranium or other strategic special nuclear materials must be able to protect the material from theft by a DBT adversary -- a violent attack by a sophisticated paramilitary group. This requirement drives the need for such facilities to have a dedicated and well-trained armed response force capable of neutralizing the DBT adversary.
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From page 206... ...
NRC will handle applications for possession and use of HALEU at reactors and fuel cycle facilities on a case-by-case basis, and if necessary, will require additional security measures as license conditions. This process could be burdensome if the U.S.
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From page 207... ...
According to this expert, while there are many aspects of advanced reactor designs that will have a greater impact on safeguards than the use of HALEU, the use of HALEU is one common factor of almost all designs being supported by the United States (Stern, 2021)
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From page 208... ...
26 For example, according to the IAEA Safeguards Implementation Report for 2019, there were a total of 804 PDI for 21 low-enriched uranium fuel fabrication plants in states with comprehensive safeguards agreements and additional protocols in place, averaging less than 40 PDIs per facility -- an order of magnitude less than the MRIE for a 500 MT/y facility (IAEA, 2020b)
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From page 209... ...
6.3.5 Proliferation and Security Risks of Fuel Cycles Using Reprocessing and Recycling In general, closed fuel cycles using reprocessing and recycling, as discussed in Chapters 2 and 4, pose greater nuclear proliferation and security risks than once-through fuel cycles. As a result, closed fuel cycles would require the application of more intensive international safeguards and domestic physical protection measures, which can be more costly in terms of the financial, technical, and human resources needed for their implementation, than are required for once-through cycles.
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From page 210... ...
. Nonetheless, for decades there have been numerous efforts to identify ways to modify closed fuel cycles to increase the intrinsic proliferation resistance -- including the International Nuclear Fuel Cycle Evaluation and DOE's Nonproliferation Alternative Systems Assessment Program in the 1970s and 1980s.
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From page 211... ...
. As discussed in Section 6.2.5, these studies concluded that none of the alternative reprocessing schemes considered conferred significant proliferation resistance compared to PUREX, because the product streams remained attractive materials for use in nuclear weapons (largely confirming what was already known)
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From page 212... ...
The U.S. NRC also requires that loss of a formula quantity Category IA materials (generally strategic special nuclear material items that can be carried by one person inconspicuously)
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From page 213... ...
Loss Scenario All 1% All 3% All 5% Abrupt Loss 100% 99% 63% Protracted Loss 1 100% 93% 31% Protracted Loss 2 100% 66% 13% SEID (kg Pu) 1.9 5.5 9.1 NOTE: IAEA = International Atomic Energy Agency; RSD = relative standard deviation; SEID = standard error of the inventory difference.
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From page 214... ...
Conventional neutron detectors used for nondestructive assay of plutonium and other actinides are sensitive to gamma-ray backgrounds, which limits their utility for measurements of impure mixtures at pyroprocessing plants, such as the uranium/transuranic product. Los Alamos National Laboratory has developed a High-Dose Neutron Detector that utilizes boron-lined proportional counters with argon and CO2 gas, which reportedly can function with gamma dose rates up to 800 rem/hour with a 30 percent reduction in neutron detection efficiency, allowing for measurements of the neutron multiplication to less than 5 percent uncertainty (Croce et al., 2021)
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From page 215... ...
. 6.3.5.5 Security Aspects of Alternative Closed Fuel Cycles The question of whether alternative closed fuel cycles can be designed to have significantly lower security risks than PUREX-based systems depends fundamentally on whether the materials that are produced, stored, processed, and transported are of low attractiveness for substate actors seeking to acquire nuclear weapons.
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From page 216... ...
NRC commissioners disapproved a staff proposal to include americium and neptunium in a revised material categorization scheme. Given the potential that advanced reactor fuel cycles involving separated streams or mixtures that include these elements may be developed in the future, the U.S.
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