Nuclear Engineering Commons^™

Distributed Sensor Network Data Fusion For Nuclear Security Applications, Ian Robert Stewart

Doctoral Dissertations

Detecting, locating, and interdicting radiological materials out of regulatory control or that pose a threat to the general public remains a high national security priority. Conventional methods employed a radiation detection system to detect radiological materials and alert the appropriate authorities for interdiction procedures. More recently, the concept of operations has focused to deploying multiple radiation detection systems to detect and track radiological materials, providing more detail to aid end-users during the interdiction process. The research proposed in this document utilizes data from a distributed sensor network to detect and track radiation anomalies through a network. The primary original contributions …

Development Of (Α,N) Signatures As A Viable Safeguards Measurement For Electrochemical Reprocessing, Stephen N. Gilliam

Doctoral Dissertations

As interest grows in electrochemistry for material separations and reprocessing of nuclear fuel research and development into the safegaurdability of such a system is needed. Plutonium quantification via (α,n) neutrons within the electrorefiner vessel is examined as a potential alternative means to the traditional spontaneous fission tracking. An MCNP model of an Epi-Thermal Neutron Multiplicity counter was used in the calculation of curium from a sample of curium, plutonium, and eutectic salt. This and the multiplicity variable alpha, the ratio between (α,n) neutron and spontaneous fission, were then used to define the plutonium mass as it related to its (α,n) …

Multiphysics Assessment Of Accident Tolerant Fuel, Cladding, And Core Structural Material Concepts, Jacob Preston Gorton

Doctoral Dissertations

The severe accident at the Fukushima-Daiichi nuclear power plant in 2011 ignited a global research and development effort to replace traditionally-used materials in Light Water Reactors (LWRs) with Accident Tolerant Fuel (ATF) materials. These materials are intended to extend the coping time of nuclear power plants during severe accident scenarios, but must undergo thorough safety and performance evaluations before being implemented. Four ATF concepts are analyzed in this dissertation using state-of-the-art computer modeling tools: (1) iron-chromium-aluminum (FeCrAl) fuel rod cladding, (2) silicon carbide (SiC) fiber-reinforced, SiC matrix composite (SiC/SiC) boiling water reactor (BWR) channel boxes, (3) mixed thorium mononitride (ThN) …

Development And Validation Of A Cross Correlation Function Based Indirect Flow Measurement Technique, Xiong Gao

Doctoral Dissertations

Nuclear Power Plants (NPPs) require the accurate measurement of mass flow rates. Advanced flow meters have been invented and widely applied in several current industries; however, the operation environment in nuclear power plants is especially harsh due to high temperature, high radiation and extremely corrosive conditions.. Several of the advanced reactor designs, such as liquid sodium pool reactors and integral small modular reactors, do not have conventional primary piping systems. These designs necessitate alternative methods to accurately measure primary flow.

Cross Correlation Function (CCF) flow estimation, which was proposed in the 1980s, can estimate the flow velocity indirectly without any …

Fast Neutron Assay Of Elemental Content Of Bulk Samples, Calder Emerson Lane

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this research was to analyze the capabilities of fast neutrons in the detection and analysis of various isotopes in bulk samples. The deuterium-tritium (DT) fusion reaction generates highly penetrating, high-energy (14.1-MeV) neutrons which induce nuclear reactions in irradiated targets. Neutrons and gamma rays are generated in these reactions. Emitted gamma rays are characteristic of the emitter; the gamma spectrum enables stoichiometric identification of the assayed samples. Neutron backscattering can also be used for identification of the elemental composition of the sample.

This work had three objectives. The first objective was to develop a computational technique to model …

Linking Theory Of Disruptive Technology With Nuclear Security: Uas As An Emerging And Disruptive Technology, Jason J. Karcz

Masters Theses

Technology used in nuclear security allows for many practical applications for securing material while simultaneously providing malicious opportunities for adversaries to potentially steal or misuse the material. Fixed sites and various modes of transport for nuclear and other radioactive material all can benefit from the use of new technology in mitigating against these threats. One emerging technology in nuclear security that is rapidly growing is the use of unmanned aerial systems (UAS). UASs provide a different dimension of security compared to methods that are traditionally used because of the added aerial characteristics of these devices. These devices offer new detection, …

Experimental Evaluation Of The Deadtime Phenomenon For Gm Detector: Deadtime Dependence On Operating Voltages, Bader Almutairi, Syed B. Alam, Tayfun Akyurek, Cameron S. Goodwin, Shoaib Usman

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A detailed analysis of Geiger Mueller counter deadtime dependence on operating voltage is presented in the manuscript using four pairs of radiation sources. Based on two-source method, detector deadtime is calculated for a wide range of operating voltages which revealed a peculiar relationship between the operating voltage and the detector deadtime. In the low voltage range, a distinct drop in deadtime was observed where deadtime reached a value as low as a few microseconds (22 µs for ²⁰⁴Tl, 26 µs for ¹³⁷Cs, 9 µs for ²²Na). This sharp drop in the deadtime is possibly due to reduced …

Computational Modeling Of Radiation Damage In A Multi-Phase Ceramic Waste Form Using Moose, Zeyu Chen

Theses and Dissertations

Ceramic waste forms have been proposed to replace the traditional glassy waste forms for long term stabilization of radionuclides. These waste forms are constantly exposed to self-irradiation emitted from the constituent radionuclides causing their material properties to change accordingly. It has been known that the radiation damage in waste forms is dominated by alpha particles emitted from transuranic (TRU) radionuclides. Since alpha particles usually have a range of 10~20 μm in such waste forms, some fraction of any non-transuranic containing phases (for a multiphase waste form) will be undamaged (or less damaged) if containing large enough grain sizes. Modeling and …

A Two-Dimensional Spherical-Polar Multigroup Discrete Ordinates Code For Atmospheric Particle Transport, Daniel T. Wakeford

Nuclear Engineering ETDs

A natural coordinate system for calculating neutral particle propagation in the atmosphere due to point sources is two-dimensional spherical-polar coordinates. Deterministic methods for solving the transport equation in this coordinate system require some interesting implementation details stemming from the two angular derivatives present in this form of the equation. In this dissertation, we present a bilinear discontinuous spatial discretization of the transport equation in this coordinate system. The weighted diamond difference discretization is applied to the angular derivative term in two angular dimensions, using zero-weighted starting directions to start the differencing. To our knowledge, the only previous deterministic code that …

Corrigendum: “A Correlation For Interfacial Area Concentration In High Void Fraction Flows In Large Diameter Channels” ([Chem. Eng. Sci.131 (2015) 172–186] (2015) 131 (172–186), (S0009250915002547), (10.1016/J.Ces.2015.04.004)), Joshua P. Schlegel, T. Hibiki

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

There is a Typographical Mistake in Eq. (21), Used in the Derivation of the Final Model, Which Should Read [Fourmula Presented] This Typographical Mistake is Also Present in Eq. (22b), Which is Necessary for Implementation of the Final Model, Which Should Read

Production Of Medical Radioisotopes Using Titanium Accelerator Targets, Christopher Shaun Loveless

Arts & Sciences Electronic Theses and Dissertations

Theranostic radiopharmaceuticals enable diagnostic imaging and radionuclide therapy in patients using a single molecular agent labeled with a diagnostic-therapeutic pair (e.g., 68Ga/177Lu) or a theranostic radionuclide (e.g., 131I). This theranostic approach can help inform patient-specific treatment plans and improve clinical outcomes. Radionuclide pairs used in theranostic agents fall into two categories: pseudo matched-pairs (e.g., 68Ga/177Lu) and matched-pairs (e.g., 124I/131I). Pseudo matched-pair radionuclides have similar chemistries and pharmacokinetics when bound to the same bioconjugate molecule. In contrast, identical chemistries and pharmacokinetics can be obtained by using the matched-pair radionuclides.

The isotopes of Sc include two diagnostic radioisotopes, 43Sc & 44Sc, and …

Nonlinear Dynamics Of Carbon Steel Corrosion Under Gamma Radiation, Youn Gyeong Shin

Electronic Thesis and Dissertation Repository

Corrosion of materials is still an unresolved problem affecting a multitude of industries. One of the grand challenges facing the corrosion community is the development of high-fidelity models for corrosion in actual service environments. The difficulties arise since corrosion involves transfer of metal atoms between the solid and solution phases thus making the system non-adiabatic. Interfacial transfer of atoms increases the chance of establishing systemic feedback between chemical reactions and transport processes, which results in chemical oscillation and periodic patterns on the corroding surfaces. These oscillating behavior in electrochemical measurements and pattern formation on corroding surfaces have been reported in …

A Datacentric Algorithm For Gamma-Ray Radiation Anomaly Detection In Unknown Background Environments, James M. Ghawaly Jr

Doctoral Dissertations

The detection of anomalous radioactive sources in environments characterized by a high level of variation in the background radiation is a challenging problem in nuclear security. A variety of natural and artificial sources contribute to background radiation dynamics including variations in the absolute and relative concentrations of naturally occurring radioisotopes in different materials, the wet-deposition of $^{222}$Rn daughters during precipitation, and background suppression due to physical objects in the detector scene called ``clutter." This dissertation presents a new datacentric algorithm for radiation anomaly detection in dynamic background environments. The algorithm is based on a custom deep neural autoencoder architecture called …

A 3d Image-Guided System To Improve Myocardial Revascularization Decision-Making For Patients With Coronary Artery Disease, Haipeng Tang

Dissertations

OBJECTIVES. Coronary artery disease (CAD) is the most common type of heart disease and kills over 360,000 people a year in the United States. Myocardial revascularization (MR) is a standard interventional treatment for patients with stable CAD. Fluoroscopy angiography is real-time anatomical imaging and routinely used to guide MR by visually estimating the percent stenosis of coronary arteries. However, a lot of patients do not benefit from the anatomical information-guided MR without functional testing. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a widely used functional testing for CAD evaluation but limits to the absence of anatomical information. …

Empirical Modeling Of Used Nuclear Fuel Radiation Emissions For Safeguards Purposes, Amanda M. Bachmann

Masters Theses

For nuclear nonproliferation safeguards, the ability to characterize used nuclear fuel (UNF) is a vital process. Fuel characterization ^allows for independent verification by inspectors of operator declarations of the special nuclear material flow and nuclear related activities within a facility, and an estimation of fissile material remaining in a fuel assembly. Current methods to verify this information rely heavily on non-destructive assay techniques, such as gamma spectroscopy and neutron detection measurements. While these measurements are effective tools for estimating a specific characteristic of the fuel, such as burnup or cooling time, they often require an accurate estimation of a select …

Determining The Feasibility Of Cyclic Voltammetry For Pyroprocessing Safeguards, Jonathan T. Mitchell

Masters Theses

No abstract provided.

Characterization Of Partial Charge Collection Induced By Neutron Damage In High-Purity Germanium Detectors, James W. Evans

Nuclear Engineering ETDs

This paper investigates the correlation of damage induced by neutron interactions and degradation in the spectra of HPGe detectors. As neutrons kinetically interact with germanium crystals, they create interstitial and vacancy defects within the lattice. These defects then interfere with the charge migration of electron-hole pairs and reduce resolution in the observed energy spectrum. The partial charge collection produces observable spectral changes by increasing the peak width and reducing resolution (full width half maximum). A detailed characterization using various check sources was performed before and after iterations of neutron exposure in order to observe the effects of the neutron damage. …

Eusectra: European Nuclear Security Training Centre Providing Hands-On Training And Education In Nuclear Security And Safeguards, Willem Janssens, Veronique Berthou, Abbas Kamel, Jean Galy, Klaus Luetzenkirchen, Klaus Mayer, Stefan Nonneman

International Journal of Nuclear Security

The European Nuclear Security Training Centre (EUSECTRA) inaugurated under this global name about 10 years ago and operated by the European Commission Joint Research Centre (JRC), located both on the Karlsruhe (Germany) and Ispra (Italy) sites, includes a large variety of capacity building and professional development activities which span from the hands-on training for nuclear security and safeguards actors (e.g. respectively border guards or customs and nuclear inspectors) to educational efforts in both nuclear security and safeguards. Whereas the first ones, which gave rise to the new name, focus mainly on detection, on-site assistance, crime-scene management, technical reach-back and nuclear …

Promoting Nuclear Security Education And Training Activities At Amity University, India, Arpita Datta, Dr. Alpana Goel

International Journal of Nuclear Security

In the present era of global nuclear governance, it is the responsibility of every individual not only the security personals to be accountable for the security of nuclear materials, facilities and radioactive materials. Amity university and other universities of India are the largest educational networks for young professionals who will enter the nuclear programme in India and will be involved in the management of nuclear and other radioactive materials in a wide variety of applications such as hospitals, industrial applications and nuclear facilities. Amity University Uttar Pradesh is taking leading part to sensitize the importance of nuclear security amongst the …

High Heat Flux Testing Facilities And An Electrothermal-Arc Plasma Source For Plasma-Material Interaction Studies And Diagnostic Development, Elizabeth G. Lindquist

Faculty Publications and Other Works -- Nuclear Engineering

Tokamak plasma-facing components experience significant stresses from plasma-material interactions (PMI) due to cyclic high thermal loads, plasma exposure, and neutron irradiation. As the field progresses to reactor-level power fluxes, the harsh fusion environment demands much of plasma-facing materials.

Chapter 1 introduces plasma-material interactions and the condition plasma-facing components are expected to endure. While plasma exposure and neutron radiation damage are introduced, the synergistic effects of cyclic high thermal loads under plasma exposure are focused on. This motivates the need for plasma-facing materials studies.

Chapter 2 gives a brief overview of many high heat flux test facilities worldwide. Three prominent high …