Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Nuclear Engineering

Major Professor

Howard L. Hall

Committee Members

Alan S. Icenhour, Laurence F. Miller, Steve E. Skutnik, Brandon C. Prins


Uranium enrichment finds a direct and indispensable function in both peaceful and nonpeaceful nuclear applications. Today, over 99% of enriched uranium is produced by gas centrifuge technology. With the international dissemination of the Zippe archetypal design in 1960 followed by the widespread illicit centrifuge trafficking efforts of the A.Q. Khan network, traditional barriers to enrichment technologies are no longer as effective as they once were. Consequently, gas centrifuge technology is now regarded as a high-priority nuclear proliferation threat, and the international nonproliferation community seeks new avenues to effectively and efficiently respond to this emergent threat.

Effective response first requires an accurate and dependable predictive capability. Modern scientific efforts have focused on predicting the hydrodynamics within a single centrifuge. Unfortunately, a single centrifuge alone is not a viable proliferation threat. An arrangement of hundreds or thousands of centrifuges operating in concert to produce meaningful quantities of enriched uranium, however, is. Such an arrangement is called a cascade, which represents the indivisible unit of the enrichment proliferation threat. Cascade theory was deemed a conquered science since before the advent of the gas centrifuge. It is suspected that the international nonproliferation community requires more robust developments in cascade theory rather than centrifuge hydrodynamics models.

Consequently, many of the traditional cascade analysis methodologies still heavily rely upon ideal cascade theory developed during the Manhattan Project and its modest improvements since. This study proposes a modern theory of cascade dynamics to compliment classical ideal cascade theory. This novel contribution includes the addition of time-dependent and non-ideal cascade analysis.

The benefits of employing cascade dynamics are demonstrated in this study using the NonProliferation Analysis of Centrifuge Cascade (NPACC) methodology. NPACC estimations are benchmarked to traditional ideal cascade analysis methods currently used by the nonproliferation community. It is discovered that traditional methods are unequipped to accurately estimate the performance of realistic centrifuge cascades as their physical design and feed rate result in deviations from ideal conditions. Implementation of cascade dynamics is expected to more accurately predict the performance of centrifuge cascades and therefore better meet the needs of the international nonproliferation community.


This dissertation is determined by the U.S. Department of Energy to contain technical information whose export is restricted by U.S. Export Control Laws and Regulations. Violations via unauthorized dissemination and/or disclosure may result in administrative, civil, and/or criminal penalties under U.S. federal law. A redacted version of this dissertation is available to the Tennessee Research and Creative Exchange (TRACE) electronic database for download. However, dissemination of the complete dissertation must be limited to U.S. persons only. To obtain access to this dissertation in its complete form or the original export control determination, please contact Dr. Howard L. Hall or an export control officer at The University of Tennessee.

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