Nuclear Engineering Commons^™

Predicting Shape And Stability Of Air–Water Interface On Superhydrophobic Surfaces Comprised Of Pores With Arbitrary Shapes And Depths, B. Emami, Dr. Hooman Vahedi Tafreshi, M. Gad-El-Hak, Gary C. Tepper

Mechanical and Nuclear Engineering Publications

An integro-differential equation for the three dimensional shape of air–water interface on superhydrophobicsurfaces comprised of pores with arbitrary shapes and depths is developed and used to predict the static critical pressure under which such surfaces depart from the non-wetting state. Our equation balances the capillary forces with the pressure of the air entrapped in the pores and that of the water over the interface. Stability of shallow and deep circular, elliptical, and polygonal pores is compared with one another and a general conclusion is drawn for designing pore shapes for superhydrophobicsurfaces with maximum stability.

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.

Quantification Of Stochastic Uncertainty Propagation For Monte Carlo Depletion Methods In Reactor Analysis, Quentin Thomas Newell

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Monte Carlo method provides powerful geometric modeling capabilities for large problem domains in 3-D; therefore, the Monte Carlo method is becoming popular for 3-D fuel depletion analyses to compute quantities of interest in spent nuclear fuel including isotopic compositions. The Monte Carlo approach has not been fully embraced due to unresolved issues concerning the effect of Monte Carlo uncertainties on the predicted results.

Use of the Monte Carlo method to solve the neutron transport equation introduces stochastic uncertainty in the computed fluxes. These fluxes are used to collapse cross sections, estimate power distributions, and deplete the fuel within depletion …

Spectroscopic Methods Of Process Monitoring For Safeguards Of Used Nuclear Fuel Separations, Jamie Lee Warburton

UNLV Theses, Dissertations, Professional Papers, and Capstones

To support the demonstration of a more proliferation-resistant nuclear fuel processing plant, techniques and instrumentation to allow the real-time, online determination of special nuclear material concentrations in-process must be developed. An ideal materials accountability technique for proliferation resistance should provide nondestructive, realtime, on-line information of metal and ligand concentrations in separations streams without perturbing the process. UV-Visible spectroscopy can be adapted for this precise purpose in solvent extraction-based separations.

The primary goal of this project is to understand fundamental URanium EXtraction (UREX) and Plutonium-URanium EXtraction (PUREX) reprocessing chemistry and corresponding UV-Visible spectroscopy for application in process monitoring for safeguards. By …

Design And Development Of An Advanced Thermonuclear Fusion Propulsion R&D Facility At Uahuntsville, Ross J. Cortez

Von Braun Symposium Student Posters

No abstract provided.

A Modular Design For Nuclear Battery Technology, Randy Lao

Physics

This paper is an exploration of the physics and technology behind the development and on-going research of nuclear batteries. This includes the topics of isotope radiation suitable for such a device as well as the components necessary to utilize the energy of natural decay, such as solid and liquid semiconductors. Most importantly for public use, the battery requires a safe containment system while allowing convenient modularity. An efficiency and total output comparison will be made with standard button cell and dry cell batteries. Also, a proposal is made for the design of an enclosure to contain radioactive materials. The safe …

Simulation And Validation Of Two-Component Flow In A Void Recirculation System, Oscar Eduardo Daza

Master's Theses

Nuclear power plants rely on the Emergency Core Cooling System (ECCS) to cool down the reactor core in case of an accident. Occasionally, air is entrained into the suction piping of ECCS causing voids that decrease pumping efficiency, and consequently damage the pumps. In an attempt to minimize the amount of voids entering the suction side of the pump in ECCS, a Void Recirculation System (VRS) experiment was conducted for a proof of concept purpose. While many studies have been oriented in studying two-component flow behavior in ECCS, none of them propose a solution to minimize air entrainment. As a …

Computational Study Of Passive Neutron Albedo Reactivity (Pnar) Measurement With Fission Chambers, Sandra De La Cruz

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Passive Neutron Albedo Reactivity technique (PNAR) was used to assay used nuclear fuel as a potential method for the measurement of fissionable material in fuel assemblies. A Monte Carlo transport code (MCNPX 2.6) was used to develop simulation models to evaluate the PNAR technique. The MCNPX simulated models consisted of two 17x17 Pressurized Water Reactor (PWR) used fuel assemblies; one with an initial 3 wt% uranium-235*, cooled for 20 years and second with an initial 4 wt% uranium-235*, cooled for 5 years. Each used fuel assembly was simulated at four different burn up rates of 15, 30, 45, and …

Structure Studies On Lanthanide Technetium Pyrochlores As Prospective Host Phases To Immobilize 99- Technetium And Fission Lanthanides From Effluents Of Reprocessed Used Nuclear Fuels, Thomas Hartmann, Ariana Alaniz

Festival of Communities: UG Symposium (Posters)

We performed a systematic investigation of the incorporation of 99Tc into pyrochlore oxide structures, Ln2Tc2O7, where Ln represents trivalent lanthanide Ln3+ cations, while 99Tc is atetravalent, Tc4+, metal cation. Pyrochlore compounds are high-melting temperature oxides and are recognized for their durability. Our goal in this preliminary study is to characterize and quantify the range of stability of the lanthanum technetium pyrochlore oxide phase. Hereby, powder X-ray diffraction (XRD) and Rietveld analysis were used to determine and characterize the crystalline phase content with high accuracy, and scanning electron microscopy (SEM) was used to characterize the microstructure and homogeneity of the synthesized …

An Integrated Circuit/Microsystem/Nano-Enhanced Four Species Radiation Sensor For Inexpensive Fissionable Material Detection, Randy Paul Waguespack

Doctoral Dissertations

Small scale radiation detectors sensitive to alpha, beta, electromagnetic, neutron radiation are needed to combat the threat of nuclear terrorism and maintain national security. There are many types of radiation detectors on the market, and the type of detector chosen is usually determined by the type of particle to be detected. In the case of fissionable material, an ideal detector needs to detect all four types of radiation, which is not the focus of many detectors. For fissionable materials, the two main types of radiation that must be detected are gamma rays and neutrons. Our detector uses a glass or …

Improved Analytical Analysis Of A Pressurized Water Reactor Secondary Loop, Megan J. Holba

All Capstone Projects

In the nuclear industry, the addition of poly-acrylic acid (PAA) as a dispersant to the secondary cooling loop in pressurized water reactors (PWRs) has been found beneficial in keeping the corroded Fe in solution. The purpose of this study is to measure the effectiveness of the addition of PAA to Braidwood Nuclear Power Station and other plants, to show the benefits of PAA implementation and to evaluate the current method for Fe detection. The current analytical method for the X-Ray Fluorescence Detector has an upper detection limit of 5,000 μg Fe, however, the results frequently exceed the upper limit. In …

Neutron Detection Using Gadolinium-Based Diodes, Benjamin R. Thomas

Theses and Dissertations

P-n heterojunction diodes consisting of a thin n-type layer of Gd₂O₃ deposited on both p-type Si and p-type 4H SiC substrates were explored as possible solid-state neutron detectors. 79 keV internal conversion electrons from the de-excitation of the meta-stable Gd-158 nucleus can create ionization in the depletion region of the reverse-biased diodes resulting in a detectable signal. The diodes were modeled with Davinci software to determine the feasibility of signal detection above the reverse-bias leakage current. A CASINO simulation showed that less than one percent of the internal conversion electrons deposit their full energy within the achievable …

A Study Into The Use Of Microprocessor Relays For Motor Operated Valve (Mov) Electrical Protection In Nuclear Power Plants, James Andrew Tuccillo

Master's Theses

Motor Operated Valves (MOVs) are electro-mechanical components used to isolate, divert, or introduce fluid flow. The use of microprocessor relays for actuator motor electrical protection within nuclear power plants is the focus of this thesis and is implemented by providing a new and enhanced protection scheme that provides the adequate conservatism necessary to ensure valve operation while still maintaining electrical safety and continued operational availability. The comprehensive protection scheme is designed around an advanced microprocessor relay that has the ability to simulate the thermal overload conditions of a motor operating into a destructive thermal region. Through laboratory testing, the validity …

Predicting Shape And Stability Of Air–Water Interface On Superhydrophobic Surfaces With Randomly Distributed, Dissimilar Posts, B. Emami, Hooman Vahedi Tafreshi, M. Gad-El-Hak, Gary C. Tepper

Mechanical and Nuclear Engineering Publications

A mathematical framework developed to calculate the shape of the air–water interface and predict the stability of a microfabricated superhydrophobicsurface with randomly distributed posts of dissimilar diameters and heights is presented. Using the Young–Laplace equation, a second-order partial differential equation is derived and solved numerically to obtain the shape of the interface, and to predict the critical hydrostatic pressure at which the superhydrophobicity vanishes in a submersed surface. Two examples are given for demonstration of the method’s capabilities and accuracy.

Application Of The Tdma Technique Toward The Size And Charge Distribution Measurement Of Graphite, Gold, Palladium, And Silver Aerosols, Matthew Paul Simones

All Graduate Theses, Dissertations, and Other Capstone Projects

The knowledge of charge distributions among aerosol particles has been an important topic for many years because of the strong electrostatic interactions which can greatly influence aerosol transport and evolution. Theoretical models have been developed although experimental verification has been limited because of the difficulty in measuring charged aerosols. Recently a method utilizing a tandem differential mobility analyzer (TDMA) has been shown to be applicable toward measuring both the size and charge distributions of nanosized combustion aerosols. The goal of this work is on further exploration of this method toward the measurement of non-combustion aerosols and in particular those associated …

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 …

Illicit Trafficking Of Radioactive Sources: Experiences With Fake Materials In Tanzania, Iddi Mkilaha

Tanzania Journal of Engineering and Technology (TJET)

Radioactive materials although are very useful, they are one of the catastrophic sources of mass destruction if misused. These materials have a number of positive uses which makes them very essential in our modern society. Incidences such as the bombings of the US Embassies in East Africa, the September 11, and many others had formed a basis for international responsive actions to control illicit trafficking of Radioactive and Nuclear Materials. The aim of this work is to track the movements and subsequently uses of these materials. Tanzania is one of the countries where International Nuclear Safeguards protocols are fully operational …

Analyzing The Impact Of Reactive Transport On The Repository Performance Of Triso Fuel, Gregory Schmidt

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the largest determiners of the amount of electricity generated by current nuclear reactors is the efficiency of the thermodynamic cycle used for power generation. Current light water reactors (LWR) have an efficiency of 35% or less for the conversion of heat energy generated by the reactor to electrical energy. If this efficiency could be improved, more power could be generated from equivalent volumes of nuclear fuel. One method of improving this efficiency is to use a coolant flow that operates at a much higher temperature for electricity production. A reactor design that is currently proposed to take advantage …

Triso Fuel Compact Thermal Conductivity Measurement Instrument Development, Colby Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Thermal conductivity is an important thermophysical property needed for effectively predicting fuel performance. As part of the Next Generation Nuclear Plant (NGNP) program, the thermal conductivity of tri-isotropic (TRISO) fuel needs to be measured over a temperature range characteristic of its usage. The composite nature of TRISO fuel requires that measurement be performed over the entire length of the compact in a non-destructive manner. No existing measurement system is capable of performing such a measurement.

A measurement system has been designed based on the steady-state, guarded-comparative-longitudinal heat flow technique. The system as currently designed is capable of measuring cylindrical samples …

Impact Investigation Of Reactor Fuel Operating Parameters On Reactivity For Use In Burnup Credit Applications, Tanya N. Sloma

UNLV Theses, Dissertations, Professional Papers, and Capstones

When representing the behavior of commercial spent nuclear fuel (SNF), credit is sought for the reduced reactivity associated with the net depletion of fissile isotopes and the creation of neutron-absorbing isotopes, a process that begins when a commercial nuclear reactor is first operated at power. Burnup credit accounts for the reduced reactivity potential of a fuel assembly and varies with the fuel burnup, cooling time, and the initial enrichment of fissile material in the fuel. With regard to long-term SNF disposal and transportation, tremendous benefits, such as increased capacity, flexibility of design and system operations, and reduced overall costs, provide …

A Safeguards Design Strategy For Domestic Nuclear Materials Processing Facilities., Jonathan Long

Electronic Theses and Dissertations

The outdated and oversized nuclear manufacturing complex within the United States requires its transformation into a smaller, safe, and secure enterprise. Health and safety risks, environmental concerns, and the end of the Cold War have all contributed to this necessity. The events of September 11, 2001, emphasized the protection requirements for nuclear materials within the U.S. as well as abroad.

Current Nuclear Safeguards regulations contain minimal prescriptive requirements relating to the design of new production facilities. Project management and engineering design guides require that design documents contain specific and measureable statements relating to systems requirements. The systems engineering process evaluates …

Flow Rate Measurement In A High Temperature, Radioactive, And Corrosive Environment, Taleb Moazzeni

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurate measurement of coolant flow rate is essential for determining the maximum power required by the nuclear plant operation and critical for monitoring its operation safety. However, no practical off-the-shelf flowmeter is available to satisfy all the pressing multidimensional operation requirements (i. e., high temperature, high irradiation, and high corrosion). This work thus deals with the development of a new flowmeter for nuclear power plant/reactor process-monitoring and real time analysis; this proposed flowmeter shall be able to continuously conduct robust measurements under extremely harsh environment with high irradiation, high pressure, high temperature and corrosive media. We investigate a transit-time based …