Engineering Commons^™

Determining 235u Enrichment Using A Dual-Energy Approach For Delayed Neutron Measurements, Angela Lynn Lousteau

Doctoral Dissertations

Bulk uranium items are often measured using active neutron interrogation systems to take advantage of the relatively high penetrability of neutrons, providing the ability to quickly and accurately measure uranium masses in large, dense configurations. Active techniques employ an external neutron source to induce fission in the uranium and subsequently measure emitted prompt fission or delayed neutrons. Unfortunately, the emitted neutrons from ²³⁵U [uranium-235] and ²³⁸U [uranium-238] are, for all practical purposes, indistinguishable; therefore, commonly used systems such as the Active Well Coincidence Counter, the ²⁵²Cf [californium-252] Shuffler, and other systems based on measurement of prompt or …

An Optimization Method For Matched Abundance-Ratio Cascades By Varying The Key Weight, Richard Dale Harvey

Doctoral Dissertations

The theory of multicomponent isotope separation in matched abundance-ratio cascades (MARC) has been well established by Cohen, de la Garza, von Halle, and others. Because separation factors of different isotopes vary in the same separator, isotopic weight fractions cannot be matched in the same sense as in a two-component ideal system. Therefore, the abundance ratios of the desired isotope and a selected key isotope are matched, hence the name. These ratios are matched by choosing a key weight between the two selected components of separation.

Desirable stable isotopes for separation can exist as minor components of a natural, multicomponent isotope …

Process Attribute Monitoring Approach To Gaseous Centrifuge Enrichment Plant Safeguards, Adam Michael Shephard

Doctoral Dissertations

Unattended and remote monitoring systems for the early detection of gas centrifuge enrichment plant (GCEP) misuse have long been sought by the International Atomic Energy Agency (IAEA) safeguards inspectorate, but have yet to be realized for most GCEPs. The primary misuse of concern is high enriched uranium (HEU) production but additionally include excess low enriched uranium (LEU) production and material diversion.

The current research is a feasibility study that investigates a process monitoring approach combined with passive gamma spectroscopy techniques to monitor GCEPs. In the current research, a simulated reference cascade and monitoring system is used to demonstrate several techniques …

Enrichment Determination Of Uranium Metal In Shielded Configurations Without Calibration Standards, Jason Michael Crye

Doctoral Dissertations

The determination of the enrichment of uranium is required in many safeguards and security applications. Typical methods to determine the enrichment rely on detecting the 186 keV gamma ray emitted by uranium-235. In some applications the uranium is surrounded by external shields, and removal of the shields is undesirable. In these situations, methods relying on the detection of 186 keV gamma rays fail because these gamma rays are shielded easily.

This research presents a novel method to estimate the enrichment of uranium metal when heavily shielded by high-Z materials. The method uses fast neutron tomography to estimate the geometry …

Development Of A Prognostic Method For The Production Of Undeclared Enriched Uranium, David Alan Hooper

Doctoral Dissertations

As global demand for nuclear energy and threats to nuclear security increase, the need for verification of the peaceful application of nuclear materials and technology also rises. In accordance with the Nuclear Nonproliferation Treaty, the International Atomic Energy Agency is tasked with verification of the declared enrichment activities of member states. Due to the increased cost of inspection and verification of a globally growing nuclear energy industry, remote process monitoring has been proposed as part of a next-generation, information-driven safeguards program. To further enhance this safeguards approach, it is proposed that process monitoring data may be used to not only …