The comparative evaluation of nuclear fuel cycle proliferation resistance (PR) is of a significant interest to the policymaking community, particularly in light of a recognized need to develop a more sustainable nuclear waste management strategy.
While robust probabilistic risk assessment (PRA)-based methods for PR evaluation have been developed by experts at the national laboratories, such methods are generally resource-intensive and often rely upon sensitive, non-public data to perform their analyses. In as much, there remains a strong need for open-source alternative PR models which can be used by the academic and policymaking communities, particularly for such tasks as scoping analysis of novel fuel cycles.
An alternative to PRA has been in attribute-based models, such as attribute analysis (AA) and multi-attribute utility analysis (MAUA), which characterize PR through the use of multiple independent “barriers” to a proliferation attempt. Using one such method developed at NC State (the Fuzzy Logic Barrier model) as a demonstration platform, this study describes a methodology for enhancing PR evaluation using such models. These enhancements include the exploration of system PR dynamics via direct coupling with nuclear materials characterization analysis (via nuclear fuel depletion codes such as SCALE) and methods to reduce the inherent subjectivity of attribute weighting. In addition, improvements to the Fuzzy Logic Barrier model are presented which are designed to draw upon verified physical data for barrier performance evaluation as much as possible.
A wide variety of nuclear fuel cycle configurations were evaluated using this methodology. These fuel cycles fall into three categories: “open cycles” with no actinide recycling, “modified open cycles” which consist of limited actinide recycling (e.g., separating plutonium for single-recycle in mixed-oxide fuels), and “fully closed” cycles consisting of the recovery of all transuranic materials in spent nuclear fuel for use in fast-spectrum reactors. The characteristics of system PR were explored for each of these fuel cycle classes, including the dynamics of system PR in response to the fuel cycle parameters identified above. The dynamics of system PR showed the strongest response for parameters which show a sustained “cascade” throughout the fuel cycle, such as uranium fuel burnup (impacting the plutonium composition) in partially-closed and full-closed fuel cycles, affected also by the choice of actinide recovery strategy.
The technique of Adversary Pathway Analysis (APA) is also developed in this study as an additional means of enhancing AA/MAUA methods for fuel cycle PR analysis. APA involves the characterization of fuel cycle PR as a function of assumed adversary capabilities and final target material. This technique can be used to refine PR evaluation carried out in AA/MAUA methods by providing an analysis of the convergent pathways evaluated in PRA-based techniques, thus providing a “bridge” between the methodologies.
Finally, an evaluation was made as to the effect of simplifications in the nuclear fuel depletion calculation as well as cross-section uncertainty effects upon the material attractiveness calculation used for PR analysis. Based upon a comparative evaluation of material attractiveness based on data obtained from ORIGEN-S, a more sophisticated lattice physics model calculated in TRITON, and experimental data, characterization of material attractiveness was carried out as function of fuel burnup for mixtures consisting both of pure plutonium and transuranic materials. While reactor simplifications such as homogeneous core enrichments impact factors such as the total plutonium produced, such simplifications do not adversely affect material attractiveness evaluations compared to higher-fidelity lattice physics calculations and experimental data. Other simplifying assumptions such as a uniform irradiation power history (e.g., compared to the actual non-uniform power history) do not produce unreasonable differences in evaluated material attractiveness and thus may be used for PR evaluation purposes.
|School:||North Carolina State University|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 72/12, Dissertation Abstracts International|
|Keywords:||Fuel cycle, Nuclear fuel, Proliferation resistance|
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