Nuclear Engineering Commons^™

Development Of A Nitrogen Incorporated Ultrananocrystalline Diamond Film Based Field Emitter Array For A Flat Panel X-Ray Source, Chrystian Mauricio Posada

Doctoral Dissertations

"As an alternative to conventional X-ray sources, a flat panel transmission X-ray source is being developed. A field emitter array (FEA) prototype to be incorporated as cold cathode in this flat panel X-ray source was fabricated for this work. Using the Particle-in-Cell code OOPIC Pro, an initial FEA was designed through simulations. Based on the simulation results, a FEA prototype was fabricated using conventional microfabrication techniques. Planar nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) films were used as field emitters. This N-UNCD based FEA prototype was composed of 9 pixels distributed in a 3x3 array, with a pixel size of 225x225 µm, and …

Development Of A Flat-Panel X-Ray Source, Edwin Joseph Grant

Doctoral Dissertations

"A novel flat-panel transmission type X-ray source was developed for both medical and industrial use. Depending on the geometry of the given situation, the flat-panel X-ray source could be used in tomography, radiography or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. The design incorporates a field emission cathode made of ultra-nanocrystalline diamonds (UNCD) doped with nitrogen. These field emitters show good electron output at low power and can be deposited over large areas as is the case with carbon nanotube "forest" (CNT) cathodes. This work presents …

Determination Of Minor And Trace Elements Concentration In Kidney Stones Using Elemental Analysis Techniques, Anjali Srivastava

Masters Theses

"The determination of accurate material composition of a kidney stone is crucial for understanding the formation of the kidney stone as well as for preventive therapeutic strategies. Radiations probing instrumental activation analysis techniques are excellent tools for identification of involved materials present in the kidney stone. The X-ray fluorescence (XRF) and neutron activation analysis (NAA) experiments were performed and different kidney stones were analyzed. The interactions of X-ray photons and neutrons with matter are complementary in nature, resulting in distinctly different materials detection. This is the first approach to utilize combined X-ray fluorescence and neutron activation analysis for a comprehensive …

Feasibility Study Of A Two-Fluid Small Modular Molten Salt Reactor With In Core Heat Removal Capability, Brandon James Lahmann

Masters Theses

"A feasibility study of a two-fluid small modular molten salt reactor (MSR) with in core heat removal was performed. The initial fuel block dimension for the configuration was based on the Fuji MSR. The fuel was a mixed fluoride salt of density 3.25 g/cc, composed of 71 LiF - 16 BeF₂ - 12 ThF₄- 1 ²³³UF₄ molar percentages. The coolant salt was Li₄(FLiBe) of density 1.94 g/cc. The work set out to establish whether or not such a reactor is thermodynamically feasible when optimized for various neutronics parameters. A Java based API was …

Detector Response Function Of An Energy-Resolved Cdte Single Photon Counting Detector, Xin Liu, Hyoung Koo Lee

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

BACKGROUND: While spectral CT using single photon counting detector has shown a number of advantages in diagnostic imaging, knowledge of the detector response function of an energy-resolved detector is needed to correct the signal bias and reconstruct the image more accurately.

Experimental Investigation Of The Pebble Bed Structure By Using Gamma Ray Tomography, Fadha Shakir Ahmed

Masters Theses

"Pebble Bed Reactors offer a future for new nuclear energy plants. They are small, inherently safe, and can be competitive with fossil fuels. The fuel forms a randomly stacked pebble with non-uniform fuel densities. The thermal-mechanical behavior of pebble bed reactor core is depends strongly on the spatial variation of packing fraction in the bed and in particular on the number of contacts between pebbles, and between the pebbles and the blanket walls. To investigate these effects, experimental data to characterize bed structure are needed along with other numerical simulation and computational tools for validation.

In this study, a powerful …

Computational Modeling And Experimental Study On Optical Microresonators Using Optimal Spherical Structure For Chemical Sensing, Hanzheng Wang, Lei Yuan, Jie Huang, Xinwei Lan, Cheol-Woon Kim, Lan Jiang, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Chemical sensors based on optical microresonators have been demonstrated highly sensitive by monitoring the refractive index (RI) changes in the surrounding area near the resonator surface. In an optical resonator, the Whispering Gallery Modes (WGMs) with high quality (Q) factor supported by the spherical symmetric structure interacts with the contiguous background through evanescent field. Highly sensitive detection can be realized because of the long lifetime of the photons. The computational models of solid glass microspheres and hollow glass spheres with porous wall (PW-HGM) were established. These two types of microresonators were studied through simulations. The PWHGM resonator was proved as …

Fiber Pigtailed Thin Wall Capillary Coupler For Excitation Of Microsphere Wgm Resonator, Haining Wang, Xinwei Lan, Jie Huang, Lei Yuan, Cheol-Woon Kim, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 x 10⁴ was observed using a borosilicate glass microsphere with a diameter of 71 µm. The …

Neutron Irradiation Effects On Domain Wall Mobility And Reversibility In Lead Zirconate Titanate Thin Films, Joseph T. Graham, Geoff L. Brennecka, Paulo Ferreira, Leo Small, David Duquette, Christopher Apblett, Sheldon Landsberger, Jon F. Ihlefeld

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The effects of neutron-induced damage on the ferroelectric properties of thin film lead zirconate titanate (PZT) were investigated. Two sets of PbZr_0.52Ti_0.48O₃ films of varying initial quality were irradiated in a research nuclear reactor up to a maximum 1 MeV equivalent neutron fluence of (5.16± 0.03) x 10¹⁵ cm^-2. Changes in domain wall mobility and reversibility were characterized by polarization-electric field measurements, Rayleigh analysis, and analysis of first order reversal curves (FORC). With increasing fluence, extrinsic contributions to the small-signal permittivity diminished. Additionally, redistribution of irreversible hysterons towards higher coercive fields was …

Method And System For Scatter Correction In X-Ray Imaging, X. Wu, J. Hsieh, P. Sainath, Xin Liu

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Approaches for deriving scatter information using inverse tracking of scattered X-rays is disclosed. In certain embodiments scattered rays are tracked from respective locations on a detector to a source of the X-ray radiation, as opposed to tracking schemes that proceed from the source to the detector. In one such approach, the inverse tracking is implemented using a density integrated volume that reduces the integration steps performed.

A New Approach To Nuclear Safeguard Enhancement Through Radionuclide Profiling, Aaron Dawon Peterson

Masters Theses

"The United States has led the effort to promote peaceful use of nuclear power amongst states actively utilizing it as well as those looking to deploy the technology in the near future. With the attraction being demonstrated by various countries towards nuclear power comes the concern that a nation may have military aspirations for the use of nuclear energy. The International Atomic Energy Agency (IAEA) has established nuclear safeguard protocols and procedures to mitigate nuclear proliferation. The work herein proposed a strategy to further enhance existing safeguard protocols by considering safeguard in nuclear fuel design. The strategy involved the use …

Insufficient Ct Data Reconstruction Based On Directional Total Variation (Dtv) Regularized Maximum Likelihood Expectation Maximization (Mlem) Method, Fahima Fahmida Islam

Masters Theses

"Sparse tomography is an efficient technique which saves time as well as minimizes cost. However, due to few angular data it implies the image reconstruction problem as ill-posed. In the ill posed problem, even with exact data constraints, the inversion cannot be uniquely performed. Therefore, selection of suitable method to optimize the reconstruction problems plays an important role in sparse data CT. Use of regularization function is a well-known method to control the artifacts in limited angle data acquisition. In this work, we propose directional total variation regularized ordered subset (OS) type image reconstruction method for neutron limited data CT. …

Design, Development And Characterization Of A Novel Neutron And X-Ray Combined Computed Tomography System, Vaibhav Sinha

Doctoral Dissertations

"Visualizing the three dimensional structure of objects (e.g. nuclear fuel, nuclear materials, explosives and bio materials) and phenomena (e.g. particle tracking) can be very important in nondestructive testing applications. Computed tomography systems are indispensable tools for these types of applications because they provide a versatile non-destructive technique for analysis. A novel neutron and X-ray combined computed tomography (NXCT) system has been designed and developed at the Missouri University of Science & Technology. The neutron and X-ray combined computed tomography system holds much promise for non-destructive material detection and analysis where multiple materials having similar atomic number and differing thermal cross …

Cfd Simulation Of Void Flow In Eccs, Lifeng Wang

Masters Theses

"Emergency core cooling system (ECCS) has been studied extensively for reactor safety. Emergency core cooling system (ECCS) is designed to make sure the reactor core it is protected by providing sufficient heat removal during accident conditions. In a loss-of-coolant-accident (LOCA) scenario, the ECCS is designed to take over the reactor core cooling by drawing water from a reservoir or tank. Voids may be introduced into the ECCS through a variety of means leading to total or partial loss of suction supply, or through gas depressurization resulting from difference in gas saturation pressure and ambient pressure. The transportation of voids through …

Method And Apparatus For Adaptive Scatter Correction, Xin Liu, J. Hsieh, X. Wu

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A CT system includes a rotatable gantry having an opening to receive an object to be scanned, an x-ray source configured to project an x-ray beam toward the object having a primary intensity, a detector configured to detect high frequency electromagnetic energy passing through the object and output imaging data, and a data acquisition system (DAS) connected to the detector and configured to receive the imaging data. The system also includes a computer programmed to obtain image projection data of the object from the DAS, correct the projection data using a scatter function that is based at least on a …

Optical Microresonator Based On Hollow Sphere With Porous Wall For Chemical Sensing, Hanzheng Wang, Lei Yuan, Cheol Woon Kim, Qun Han, Tao Wei, Xinwei Lan, Hai Xiao

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A porous-wall hollow glass microsphere (PW-HGM) was investigated as an optical resonator for chemical vapor sensing. a single mode optical fiber taper was used to interrogate the micro resonator. Adsorption of chemical molecules into the nanosized pores induced a refractive index change of the thin wall and thus a shift in its resonance spectrum. the PW-HGM resonator had shown higher vapor detection sensitivity in comparison with a solid microsphere under similar test conditions. © 2011 Optical Society of America.

Hot Channel Determination And Burnup Analysis Of Missouri University Of Science And Technology Research Nuclear Reactor, Kelly Christopher Rogers O'Bryant

Masters Theses

"A burnup analysis has been performed on the Missouri University of Science and Technology (Missouri S&T) Research Nuclear Reactor (MSTR). With use of the Monte Carlo neutronics depletion code MCNPX, burned material was input into a neutronics model (burned model) in order better simulate MSTR core characteristics. Simulated burnup values of ²³⁵U for the past twenty years of MSTR operations totaled 14.266 grams, slightly less than the 14.527 grams reported by the reactor staff. A distribution of ²³⁵U was simulated and a burnup map was developed.

Using the updated fuel material, the hot channel of the current configuration of the …

Verification Of A Monte Carlo Model Of The Missouri S&T Reactor, Brad Paul Richardson

Masters Theses

The purpose of this research is to ensure that an MCNP model of the Missouri S&T reactor produces accurate results so that it may be used to predict the effects of some desired upgrades to the reactor. The desired upgrades are an increase in licensed power from 200 kW to 400kW, and the installation of a secondary cooling system to prevent heating of the pool. This was performed by comparing simulations performed using the model with experiments performed using the reactor. The experiments performed were, the approach to criticality method of predicting the critical control rod height, measurement of the …

Wavelet Based Contrast Limited Histogram Equalization For Contrast Enhancement Of Digital Mammography, Ashish Vighnahar Avachat

Masters Theses

"Mammography has been the most efficient tool for screening of microcalcification and cancer tissues; however, the raw images produced by mammography systems are usually of poor contrast. In order to use these raw images for early diagnosis; their contrast, sharpness and noise need to be enhanced. Among these important enhancement parameters contrast enhancement is critical. A novel algorithm is introduced which blends wavelet transforms with Contrast Limited Adaptive Histogram Equalization (CLAHE) for contrast enhancement. In this algorithm, the input image is decomposed to its low frequency and high frequency components in wavelet domain. Decomposed coefficients from different bands are then …

Determination Of Linear Attenuation Coefficients Of Chemically Bonded Phosphate Ceramics, Jason Joseph Pleitt

Masters Theses

"Chemically Bonded Phosphate Ceramics (CBPCs) is a composite based material formed in a manner similar to cements. CBPCs have shown to be a good structural material with excellent thermal resistance properties. They have also been shown to have potential as a radiation shield. By incorporating various powders into the ceramic the improvement in its radiation shielding properties are examined. The method for obtaining the linear attenuation coefficients for CBPCs as well as MCNP simulated results for gamma and neutrons are presented"--Abstract, page iv.

Production And Characterization Of Supported Palladium Nanoparticles On Multiwalled Carbon Nanotubes By Gamma Irradiation, Jessika Viviana Rojas Marin

Masters Theses

"Carbon nanotubes are being studied for a variety of applications due to their outstanding mechanical, chemical, electrical, and optical properties that make them interesting in different areas. Nowadays, different methods to modify the structure of the nanotubes are being developed in order to expand the application fields of such materials. In this work, palladium nanoparticles were directly produced and supported on multi-walled carbon nanotubes (MWCNT) by gamma irradiation. A solution with a 2:1 water-isopropanol ratio was prepared and mixed with palladium chloride as precursor of palladium ions. Radiolysis of water produces certain species that reduce the ions down to a …

Simulation Of The Field Electron Emission Characteristics Of A Flat Panel X-Ray Source, Chrystian Mauricio Posada ArbeláEz

Masters Theses

"A distributed flat panel x-ray source is designed as an alternative for medical and industrial imaging fields. The distributed x-ray source corresponds to a two dimensional array of micro (~100μm) x-ray cells similar in format to a field emission display. In this paper the electron field emission characteristics of a single of the proposed micro-sized x-ray cells are simulated. The field electron emission from the CNTs-based cathode is simulated using the Particle-In-Cell code OOPIC Pro. The electron source is simulated as a triode structure, composed of an emitting cathode, extracting grid and anode. The possibility of using focusing lenses to …

Density Determination Of Tristructural-Isotropic Nuclear Fuel Using Multiple Projection X-Ray Radiography, Frank Angelo Strantz

Masters Theses

"Effective methods of enhancing the safety and efficiency of the nuclear power industry embolden its perception and economic viability. Fuel reliability is an essential component of the prosperity of next generation high temperature reactors; as such, an equally dependable quality control method is mandatory. Tristructural-isotropic (TRISO) fuel, the fuel developed for use in these reactors, utilizes density measurement of coating layers as a standard for quality control. Common methods of measuring density, such as sink-float and ceramography are destructive, and as such generate radioactive waste, take a relatively long time to prepare samples, rely on a low sampling rate to …

Upgrade And Simulation Of The Subcritical Assembly At Missouri University Of Science And Technology, Lucas Powelson Tucker

Masters Theses

"The Missouri University of Science and Technology Subcritical Assembly (S&TSub) was brought back into service and upgraded with a new neutron detection system and internet access. Before the upgrade neutron counting was only possible in one location. Using a movable detection system housed in acrylic tubes measurements can now be taken in any empty fuel location and at any height within the tube, making three dimensional flux mapping a possibility. By connecting the new detection system to a Canberra Lynx Digital Signal Analyzer, remote users can have limited data collecting capabilities. To further enhance the potential of the facility, an …

Contrast Enhancement Of Digital Mammography Based On Multi-Scale Analysis, Muhammad Imran Khan Abir

Masters Theses

"A contrast enhancement algorithm is developed for digital mammograms aiming to assist radiologists in discerning early breast cancer easily. The algorithm is based on a Laplacian pyramid framework image processing technique. The mammogram is decomposed into three frequency sub-bands, low, mid, and high frequency sub-band images. The lower sub-band image contains very fine details and higher level contains coarser features. In this method contrast enhancement is achieved from high and mid sub-bands by decomposing the image based on multi-scale Laplacian pyramid and enhance contrast by image processing. Several mapping functions are applied on sub-band images based on experimental analysis. After …

Characterization Of The Neutron Flux Spectrum At The Missouri University Of Science And Technology Research Reactor, Zachary Andrew Kulage

Masters Theses

"A new remotely accessible shielded cell is being constructed at the Missouri University of Science and Technology Research Reactor (MSTR). The heavily shielded cell will be able to receive highly irradiated specimens directly from the reactor and will be equipped with radiation-hardened cameras, remote manipulators and gamma spectroscopy. The cell will allow the manipulation and monitoring of highly activated specimens from both a workstation at the MSTR and at remote locations using a Webbased internet interface. The ability to access and control the shielded cell via a remote internet connection will make it useful to a wide variety of users. …

Dead Time And Count Loss Determination For Radiation Detection Systems In High Count Rate Applications, Amol Patil

Doctoral Dissertations

"This research is focused on dead time and the subsequent count loss estimation in radiation detection systems. The dead time is the minimum amount of time required between two events to permit detection of those events individually by a radiation detection system. If events occur during the system dead time, they are lost. Such lost information can be important in many applications including high-precision spectroscopy, positron emission tomography (PET), and the scanning of spent nuclear fuel. Understanding of the behavior of radiation detection systems is important; thus this work included a comprehensive review of dead time and pulse pile-up models …

Internet-Accessible Hot Cell With Gamma Spectroscopy At The Missouri University Of Science And Technology Research Nuclear Reactor, Edwin Grant

Masters Theses

A dual-chambered internet-accessible heavily shielded facility with pneumatic access to the University of Missouri Science and Technology (Missouri S&T) 200 kW Research Nuclear Reactor (MSTR) core has been built and is currently under low level irradiation testing. The facility allows distance users doing collaborative work with Missouri S&T researchers to manipulate and analyze neutron irradiated samples remotely. The system consists of two shielded compartments, one for multiple sample storage (up to 11 samples), and the other for isolated radiation measurements and spectroscopy. The second chamber has multiple detector ports, graded shielding, and has the capability to support gamma spectroscopy using …

Interaction Between Supersonic Disintegrating Liquid Jets And Their Shock Waves, K.-S. Im, S.-K. Cheong, Xin Liu, J. Wang, M.-C. Lai, M. W. Tate, A. Ercan, M. J. Renzi, D. R. Schuette, S. M. Gruner

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The use of additional spectral filtration for dual-energy (DE) imaging using a dual-source CT (DSCT) system was investigated and its effect on the material-specific DEratio was evaluated for several clinically relevant materials. The x-ray spectra, data acquisition, and reconstruction processes for a DSCT system (Siemens Definition) were simulated using information provided by the system manufacturer, resulting in virtual DE images. The factory-installed filtration for the 80 kV spectrum was left unchanged to avoid any further reductions in tube output, and only the filtration for the high-energy spectrum was modified. Only practical single-element filter materials within the atomic number range of …

Analogy Based Modeling Of Natural Convection, Vaibhav Khane

Masters Theses

"This research is an extension of previous work on the development of an integrator or resistance-capacitance circuit analogy for natural convection. As a part of a larger project to enhance transport phenomenon on a micro-scale using radiation, this work studied the phenomenon of natural convection. Using experimental techniques and numerical simulations (FLUENT code), it investigated the transient response of a natural convection system. It proposes an integrator circuit analogy for a natural convection system. Experimental investigation with three different fluids indicated that the characteristic time constant of the system is related to the Prandtl number of the fluid. The project …