Nuclear Engineering Commons^™

Thermodynamic Modeling Of Uranium And Oxygen Containing Ternary Systems With Gadolinium, Lanthanum, And Thorium, Jacob Wesley Mcmurray

Doctoral Dissertations

The CALPHAD method is used to assess the thermodynamic properties and phase relations in the U-M-O system where M = Gd, La, and Th. A compound energy formalism (CEF) model for fluorite UO_2±x [urania] is extended to represent the complex U_1-yM_yO_2±x [urania solid solution] phases. The lattice stabilities for fictive GdO₂ [gadolinia] and LaO₂ [lanthana] fluorite structure compounds are calculated from density functional theory (DFT) for use in the CEF for U_1-yM_yO_2±x [urania solid solution phase] while U⁶⁺ [uranium 6 plus cation] is introduced into the …

Synthesis And Thermodynamic Analysis Of Volatile Beta-Diketone Complexes Of Select Lanthanides Via Gas-Phase Separations, Daniel Hanson

Doctoral Dissertations

Rapid separation techniques for fission and activation products have long been desired to supplant the slow solution-based methodologies currently used. In this work, rare earth elements were derivatized with β [beta]-diketones to synthesize rare earth complexes with high volatility suitable for gas-phase separations. Rare earth elements samarium and dysprosium were combined with hfac (1,1,1,5,5,5-hexafluoro-2,4-pentadione) and fod (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione) and analyzed using a gas-phase separation technique. Rare earth elements praseodymium and europium were combined with dpm (2,2,6,6-tetra-methyl-3,5-heptanedione) and similarly analyzed. Employing the data from the separations, the entropy (Δ [delta] S) and enthalpy (Δ [delta] H) of adsorption were evaluated mathematically based …

Automated Doppler Broadening Of Cross Sections For Neutron Transport Applications, Shane William Daniel Hart

Doctoral Dissertations

This dissertation discusses the research and development of new cross section temperature handling techniques for the SCALE computer code, which is developed and maintained at Oak Ridge National Laboratory. In particular, methods will be added to the KENO Monte Carlo code.

Areas of interest include: neutron scattering off of heavy isotopes in the epithermal energy range, implementation of Doppler pre-broadening of continuous energy one-dimensional cross-section data, implementation of interpolation on the continuous energy two-dimensional cross sections, and implementation of the direct S(A,B) [S alpha beta] method for thermal neutron scattering and interpolation on that data.

Accurate cross section scattering off …

A Study Of Energy Resolution And Non-Proportionality Of Yalo3:Ce And Gd3ga3al2o12:Ce, Samuel Bradley Donnald

Doctoral Dissertations

For many radiation detection applications, energy resolution is one of the most important detector characteristics. In well designed scintillation detectors, the energy resolution is primarily driven by two main factors - the light output and light yield non-proportionality. A great deal of research has already focused on understanding and improving the light yield of scintillation detectors; however, light yield non-proportionality is less well understood. Until recently, light yield non-proportionality was thought to be an intrinsic scintillator property with very little sample-to-sample variation. In this work, two materials have been investigated that demonstrate a variable light yield non-proportionality. The first material …

A Sensor For Oxygen In A Potassium-Sodium Alloy, Michael George Pastis

Masters Theses

This project supports a research project to determine the configuration for heat exchanger welds in a space reactor. The reactor is a sodium-potassium (NaK) cooled reactor for use on future missions on the lunar surface or on Mars. Various types of welds in Type 316L stainless steel have been positioned in a furnace which is part of a NaK test loop. The specimens are bathed in circulating NaK at 600 degrees centigrade.

Since the oxygen concentration in the NaK is a major factor in corrosion of the weld specimens, it must be carefully monitored and controlled. However, few techniques are …

Characterization Of Lithium-6 As A Commercial Helium-3 Alternative For Nuclear Safeguards And Security, Alexander Martin Okowita

Masters Theses

Helium-3 detectors are efficient, reliable neutron detectors, but their high demand has reduced their supply to a very miniscule level, making them very expensive. The goal of this project is to test and evaluate an alternative produced by industry. Current testing is being done with a Lithium Zinc Sulfide (⁶LiF:ZnS(Ag)) detector from Aspect used in their portal monitors.

There are three basic requirements for neutron detectors used in nuclear safeguards and security: 1) high absolute detection efficiency, 2) maintaining neutron detection efficiency when simultaneously exposed to a high gamma ray exposure rate, and 3) the ability to maintain …

Modeling Integral Fuel Burnable Absorbers Using The Method Of Characteristics, Erik Daniel Walker

Masters Theses

Modern core designs that utilize Westinghouse fuel technology employ the use of Integral Fuel Burnable Absorbers (IFBA) that consists of very thin coatings of boron absorber material on the fuel pellets. While IFBA has proven to be an effective burnable absorber, it does present a neutronics modeling challenge. The difficulty of modeling IFBA using the Method of Characteristics (MOC) transport method is well known, and arises from the fact that IFBA is a very small, but also very important, region in nuclear fuel. Experience in modeling IFBA at the pin cell and single assembly lattice level requires a decrease in …

Fast Fission Neutron Detection Using The Cherenkov Effect, Matthew Millard

All Theses

The Cherenkov effect in optically clear media of varying indices of refraction and composition was investigated for quantification of fast neutrons. The ultimate application of the proposed detection system is criticality monitoring. The optically clear medium, composed of select target nuclei, was coupled to a photomultiplier tube. Neutron reaction products of the target nuclei contained within the optical medium emit beta particles and gamma rays that produce Cherenkov photons within the medium which can be detected. Assessed media include quartz (SiO2), sapphire (Al2O3), spinel (MgAl2O4), and zinc sulfide (ZnS), which were irradiated with un-moderated 252Cf. Monte Carlo N-Particle (MCNP) code …

Transformation Of Uranium In A Geological Environment, Derrell Hood

All Theses

Incorporation of uranium into iron oxide minerals is a promising mechanism for the environmental immobilization of U(VI). In this study, synthesized hematite was doped with uranium and analyzed with SEM-EDS, TEM, XRD, and ICP-MS. The results of this analysis strongly indicate uranium incorporation into the mineral, as well as the possible presence of a co-precipitated uranium mineral clarkeite. Preliminary results also shows an increase in the amount of uranium associated with the hematite particles as a function of mineral aging. Cyclic Voltammetry (CV) was used to induce and characterize electrochemical changes of uranium in the doped hematite system; these changes …

Novel Deployment Of Elpasolites As A Dual Neutron / Gamma-Ray Directional Detector, Amber Lynn Guckes

UNLV Theses, Dissertations, Professional Papers, and Capstones

At a time when upholding national security has never been more important, there exists a need for the advancement of radiation detection technologies. Neutron and photon detectors are essential to fulfilling mission areas including detection and localization of missing, stolen or smuggled radiological or nuclear materials, quantification of the effects of a radiological or nuclear event, and supporting nonproliferation efforts. The aim of this study was to evaluate a new radiation detector based on the scintillation elpasolite compound Cs2LiYCl6:Ce (CLYC) for simultaneous measurements of neutron and photon flux and the localization of radiation sources. Previous studies performed on the CLYC …

Investigation And Modeling Of Uranium Polarization For The Electrorefining Of Scrap U-Mo Foils, Melissa Rose

Open Access Dissertations

A uranium molybdenum alloy fuel has been proposed to convert research and test reactors from highly enriched uranium to low enriched uranium to increase the proliferation resistance at such reactors. Pyroprocessing has been selected to recover uranium from the scrap produced in the manufacture of this novel fuel type. Electrorefining, the main separation process of pyroprocessing, is modeled through a novel approach using corrosion theory. To use corrosion theory, knowledge of uranium polarization and kinetic parameters such as Tafel constant, transfer coefficient and exchange current density are required. Uranium polarization was investigated at five temperatures and three scan rates in …

Hydrogen Loading System Development And Evaluation Of Tritiated Substrates To Optimize Performance In Tritium Based Betavoltaics, Thomas E. Adams

Open Access Dissertations

State-of-the-art hydrogen loading system onto thin metallic films based on differential pressure in calibrated chambers has been developed for conditions pressures and temperatures up to 69 bar and 500°C, respectively. Experiments on hydrogen loading on to palladium films of thickness 50 and 250 nm were conducted at pressure ranging from 0.2 bar to 10 bar at temperature 310°C. For first time film hydrogen loading was carried out at 1 bar and at room temperature which temperature. Beta flux exiting surface of metal tritide films has been modeled with MC-SET (Monte Carlo Simulation of Electron Trajectories in solids). Surface beta flux …

Experimental Study Of Droplet Capable Conductivity Probe, Yikuan Yan

Open Access Theses

This research focus on experimentally studying the performance of the newly designed Droplet Capable Conductivity Probe (DCCP). ^ A literature review is performed to illustrate the development of current two-fluid model and interfacial area transport equation. Previous conductivity probe instrumentation is also reviewed. The limitations of current conductivity probe design are described and the necessity of developing DCCP is illustrated. ^ The concept of DCCP-2 and DCCP-4 are introduced and experiments are performed to benchmark the capability of DCCP-4.

Thick Target Yield Of Th-229 Via Low Energy Proton Bombardment Of Th-232, Justin Reed Griswold

Masters Theses

Actinium-225 is one of the more effective radioisotopes used in alpha radioimmunotherapy. Due to its ten-day half-life, it is more efficient to create its precursor, ²²⁹Th [Thorium-229] (t_1/2[half-life] = 7932 ± 55 years). In this work, ²²⁹Th was produced via 40 MeV [Mega electron Volts] proton bombardment of a thick ²³²Th [Thorium-232] target. The irradiation took place at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL). The target, consisting of 23 stacked natural thorium foils (137 mg/cm² [milligrams per square centimeter] each), was irradiated with 50 nA [nanoamps] of …

Neutron Spectroscopy With Scintillation Detectors Using Wavelets, Jessica Hartman

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this research was to study neutron spectroscopy using the EJ-299-33A plastic scintillator. This scintillator material provided a novel means of detection for fast neutrons, without the disadvantages of traditional liquid scintillation materials. EJ-299-33A provided a more durable option to these materials, making it less likely to be damaged during handling. Unlike liquid scintillators, this plastic scintillator was manufactured from a non-toxic material, making it safer to use, as well as easier to design detectors. The material was also manufactured with inherent pulse shape discrimination abilities, making it suitable for use in neutron detection.

The neutron spectral unfolding …

Correlating Grain Size To Radiation Damage Tolerance Of Tungsten Materials Exposed To Relevant Fusion Conditions, Sean Robert Gonderman

Open Access Theses

Tungsten remains a leading candidate for plasma facing component (PFC) in future fusion devices. This is in large part due to its strong thermal and mechanical properties. The ITER project has already chosen to use an all tungsten divertor. Despite having a high melting temperature and low erosion rate, tungsten faces a large variety of issues when subject to fusion like conditions. These include embrittlement, melting, and extreme morphology change (growth of fuzz nanostructure). The work presented here investigates mechanisms that drive surface morphology change in tungsten materials exposed to fusion relevant plasmas. Specifically, tungsten materials of different grain sizes …

A Bayesian Approach To Broad-Area Nuclear And Radiological Search Operations, Samuel James Willmon

Doctoral Dissertations

This dissertation describes the development, implementation, and initial performance testing of the Broad-Area Search Bayesian Processor (BASBP). The BASBP is a novel FORTAN code designed to combine the data from aerial radiation detection platforms with available geo-spatial data using Bayesian techniques to provide updated parameter estimates of the problem space. By employing empirical fits to the Monte Carlo photon flux estimates generated using MCNP6, the core BASBP model accounts for the increasing significance of photon scattering and absorption events with source-detector range. The BASBP employs Bayesian signal processing methods to estimate both the spatially varying background and the most likely …

Particle Modeling Of Fuel Plate Melting During Coolant Flow Blockage In Hfir, Hiraku Nakamura

Doctoral Dissertations

Cooling channel inlet flow blockage has damaged fuel in plate fueled reactors and contributes significantly to the probability of fuel damage based on Probabilistic Risk Assessment. A Smoothed Particle Hydrodynamics (SPH) model for fuel melt from inlet flow blockage for the High Flux Isotope Reactor is created. The model is coded for high throughput graphics processing unit (GPU) calculations. This modeling approach allows movement toward quantification of the uncertainty in fuel coolant flow blockage consequence assessment. The SPH modeling approach is convenient for following movement of fuel and coolant during melt progression and provides a tool for capturing the interactions …

Development Of A Method For Incorporating Fault Codes In Prognostic Analysis, Eric Allen Strong

Doctoral Dissertations

Information from fault codes associated with a component may be used as an indicator of its health. A fault code is defined as a timestamp at which a component is not operating according to recommended guidelines. The type of fault codes which are relevant for this analysis represent mild or moderate deviations from normal behavior, rather than those requiring immediate repair. Potentially, fault codes may be used to determine the Remaining Useful Life (RUL) of a component by predicting its failure time, which will improve safety and reduce maintenance costs associated with the component. In this dissertation, methods have been …

Development Of A Fluka-Based Lookup Tool For Rapid Analysis Of Radiation Exposures In Space Environments, John Macdougall Brittingham

Doctoral Dissertations

Monte Carlo transport codes such as FLUKA provide an accurate and effective method to model the transport of space radiation. However, their use in time-sensitive applications is limited because they do not generate results as quickly as other methods, such as deterministic transport codes. The development of a pre-calculated lookup tool for use in complex space radiation environments allows the calculation of space radiation quantities such as dose, dose equivalent, and fluence using Monte Carlo results with minimal loss of accuracy. In this work, a lookup tool suitable for rapidly estimating radiation exposures is developed using the FLUKA Monte Carlo …

Multi-Cycle Boiling Water Reactor Fuel Cycle Optimization, Keith Everette Ottinger

Doctoral Dissertations

A multi-cycle nuclear fuel cycle optimization code, BWROPT (Boiling Water Reactor OPTimization), has been developed. BWROPT uses the Parallel Simulated Annealing (PSA) algorithm to solve the coupled out-of-core and in-core optimization problems. There are two depletion methods used for the in-core optimization: the Haling depletion and a Control Rod Pattern (CRP) search. The result of this optimization is the optimum new fuel inventory and the core loading pattern for the first cycle considered in the optimization. Several changes were made to the optimization algorithm with respect to other nuclear fuel cycle optimization codes that use PSA. Instead of using constant …

Time Correlated Measurements Using Plastic Scintillators With Neutron-Photon Pulse Shape Discrimination, Norman Edison Richardson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Since the beginning of the nuclear age, there has been a strong demand for the development of efficient technologies for the detection of ionizing radiation. According to the United States' Department of Energy, the accurate assessment of fissile materials is essential in achieving the nonproliferation goals of enhancing safety and security of nuclear fuel cycle and nuclear energy facilities [1]. Nuclear materials can be characterized by the measurement of prompt and delayed neutrons and gamma rays emitted in spontaneous or induced fission reactions [2] and neutrons emitted in fission reactions are the distinctive signatures of nuclear materials. Today, the most …

Solute Additives And Neutron Absorber Alloys For The Improvement Of Spent Fuel Pool Safety And Increased Storage Space, Seth H. Jobe, John R. Chalmers, Zach Hensley, Austin O'Connor, Nathan Shoman, Matthew Weeks

Chancellor’s Honors Program Projects

No abstract provided.

Improvement Of Spent Fuel Storage With Advanced Mechanical Shielding Placement, Gordon M. Petersen, Nicole Galante, Hannah Hale, Dylan Richardson, Robert Vance

Chancellor’s Honors Program Projects

No abstract provided.

Cd Dipping To Reduce Reactivity Of Fuel Assemblies In Spent Fuel Pools, John Clark Stooksbury

Chancellor’s Honors Program Projects

No abstract provided.

Production Of Nuclear Debris Surrogates For Forensic Methods Development, Joshua James Molgaard

Masters Theses

A novel method for producing synthetic debris similar to the melt glass produced by nuclear surface testing is demonstrated. Melt glass from the first nuclear weapon test (commonly referred to as trinitite) is used as the benchmark for this study. These surrogates can be used to simulate a variety of scenarios and will serve as a tool for developing and validating forensic analysis methods.

The ultimate goal is to provide the nuclear forensics community with a robust method to supply realistic yet non-sensitive surrogate materials simulating a variety of detonation scenarios. This work will also allow for the development of …

The Effects Of Shielding On Non-Destructive Analysis (Nda) And The Use Of Small-Angle Compton Scattering To Overcome Those Effects, Cory Jake Hudson

Masters Theses

The use of passive Non-Destructive Analysis (NDA) equipment and techniques are very beneficial tools in the nuclear industry that have a plethora of applications and advantages over destructive or more invasive measurement methods. Of course, NDA techniques also have many limitations including dealing with many unknown parameters, overcoming the effects of gamma ray shielding, and the reliance on making many gross assumptions in the analysis of non-destructively acquired data. These limitations can lead to biased results or extremely difficult analysis which often introduces inaccurate conclusions and/or high levels of uncertainty.

This thesis paper will focus on specific NDA equipment and …

Verification Of The Shift Monte Carlo Code Using The C5g7 And Casl Benchmark Problems, Nicholas Cameron Sly

Masters Theses

While Monte Carlo simulation has been recognized as a powerful numerical method for use in radiation transport, it has required a mixture of methods development and hardware advancement to meet these expectations in practical applications. In an effort to continue this advancement for uses of Monte Carlo simulation in ever larger capacities, Oak Ridge National Laboratory is developing the Shift hybrid deterministic/Monte Carlo code to be massively-parallel for use on parallel computing systems of all sizes. As part of this development, verification of the Monte Carlo parts of the code is needed to confirm that the current version of the …

Metal Chronometry For Pre-Detonation Nuclear Forensics Applications, Edward Thomas Peskie

Masters Theses

The ability to determine the time since forming of seized nuclear material would provide crucial data to be used in its investigation. This paper examines the time dependent processes of diffusion; to include grain boundary diffusion, and discontinuous precipitation, and assess the utility of examination of impurity and alloying element concentration profiles, for use as a pre-detonation nuclear forensics tool for determining the age of a metal sample. Several examples provided illustrate the effects of time on both binary alloys and multi-component systems. This study draws parallels from studies of diffusion in mineral samples under geologic time and proposes modifications …

Methods To Enhance Spent Fuel Pool And Dry Cask Storage, Dustin Giltnane, David Gotthold, Seth Langford, Michael Ratliff, Jessica Dawn Shewmaker, Cody Wiggins

Chancellor’s Honors Program Projects

No abstract provided.