|dc.description.abstract||A new high-fidelity integrated system method and analysis approach was
developed and implemented for consistent and comprehensive evaluations of advanced
fuel cycles leading to minimized Transuranic (TRU) inventories. The method has been
implemented in a developed code system integrating capabilities of MCNPX for highfidelity
fuel cycle component simulations.
The impact associated with energy generation and utilization is immeasurable due
to the immense, widespread, and myriad effects it has on the world and its inhabitants.
The polar extremes are demonstrated on the one hand, by the high quality of life enjoyed
by individuals with access to abundant reliable energy sources, and on the other hand by
the global-scale environmental degradation attributed to the affects of energy production
and use. Thus, nations strive to increase their energy generation, but are faced with the
challenge of doing so with a minimal impact on the environment and in a manner that is
self-reliant. Consequently, a revival of interest in nuclear energy has followed with much
focus placed on technologies for transmuting nuclear spent fuel.
In this dissertation, a Nuclear Energy System (NES) configuration was developed
to take advantage of used fuel recycling and transmutation capabilities in waste
management scenarios leading to minimized TRU waste inventories, long-term activities,
and radiotoxicities. The reactor systems and fuel cycle components that make up the
NES were selected for their ability to perform in tandem to produce clean, safe, and
dependable energy in an environmentally conscious manner. The reactor systems include
the AP1000, VHTR, and HEST. The diversity in performance and spectral
characteristics for each was used to enhance TRU waste elimination while efficiently
utilizing uranium resources and providing an abundant energy source.
The High Level Waste (HLW) stream produced by typical nuclear systems was
characterized according to the radionuclides that are key contributors to long-term waste
management issues. The TRU component of the waste stream becomes the main
radiological concern for time periods greater than 300 years. A TRU isotopic assessment
was developed and implemented to produce a priority ranking system for the TRU
nuclides as related to long-term waste management and their expected characteristics
under irradiation in the different reactor systems of the NES.
Detailed 3D whole-core models were developed for analysis of the individual
reactor systems of the NES. As an inherent part of the process, the models were
validated and verified by performing experiment-to-code and/or code-to-code
benchmarking procedures, which provided substantiation for obtained data and results.
Reactor core physics and material depletion calculations were performed and analyzed.
A computational modeling approach was developed for integrating the individual
models of the NES. A general approach was utilized allowing for the Integrated System
Model (ISM) to be modified in order to provide simulation for other systems with similar
attributes. By utilizing this approach, the ISM is capable of performing system
evaluations under many different design parameter options. Additionally, the predictive
capabilities of the ISM and its computational time efficiency allow for system
sensitivity/uncertainty analysis and the implementation of optimization techniques.
The NES has demonstrated great potential for providing safe, clean, and secure
energy and doing so with foreseen advantages over the LEU once-through fuel cycle
option. The main advantages exist due to better utilization of natural resources by
recycling the used nuclear fuel, and by reducing the final amount and time span for which
the resulting HLW must be isolated from the public and the environment due to
radiological hazard. If deployed, the NES can substantially reduce the long-term
radiological hazard posed by current HLW, extend uranium resources, and approach the
characteristics of an environmentally benign energy system.||en