Nuclear Engineering Commons^™

Searching For Stable SiNCN Clusters: Combination Of Stochastic Potential Surface Search And Pseudopotential Plane-Wave Car-Parinello Simulated Annealing Simulations, Xiaofeng F. Duan, Lingyu Huang, Larry W. Burggraf

Faculty Publications

To find low energy Si_nC_n structures out of hundreds to thousands of isomers we have developed a general method to search for stable isomeric structures that combines Stochastic Potential Surface Search and Pseudopotential Plane-Wave Density Functional Theory Car-Parinello Molecular Dynamics simulated annealing (PSPW-CPMD-SA). We enhanced the Sunders stochastic search method to generate random cluster structures used as seed structures for PSPW-CPMD-SA simulations. This method ensures that each SA simulation samples a different potential surface region to find the regional minimum structure. By iterations of this automated, parallel process on a high performance computer we located hundreds to …

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 …

Energy, U.S. Department Of, Bert Chapman

Libraries Faculty and Staff Scholarship and Research

Provides information about the U.S. Department of Energy (DOE) and its predecessor agencies and how DOE influences federal energy policy and scientific research in the western U.S.

In-Situ Condition Monitoring Of Components In Small Modular Reactors Using Process And Electrical Signature Analysis, Victor Lollar

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

Components in small modular reactors (SMRs) are located in a hazardous environment and must be monitored remotely. Electrical signature analysis (ESA) is a viable option for component monitoring as it can be implemented on-line away from the actual equipment. This research attempts to use both electrical signatures from a pump motor and process variables such as flow and pressure to effectively monitor reactor components. An experimental flow loop with pump health monitoring equipment and a data acquisition system was used for experiments. Process variables analyzed include pressure, flow rate, water level, and motor vibrations. The electrical signatures monitored were 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 …

Self-Healing Of Ionomeric Polymers With Carbon Fibers From Medium-Velocity Impact And Resistive Heating, Vishnu Baba Sundaresan, Andrew Morgan, Matt Castellucci

Mechanical and Nuclear Engineering Publications

Self-healing materials science has seen significant advances in the last decade. Recent efforts have demonstrated healing in polymeric materials through chemical reaction, thermal treatment, and ultraviolet irradiation. The existing technology for healing polymeric materials through the aforementioned mechanisms produces an irreversible change in the material and makes it unsuitable for subsequent healing cycles. To overcome these disadvantages, we demonstrate a new composite self-healing material made from an ionomer (Surlyn) and carbon fiber that can sustain damage from medium-velocity impact and heal from the energy of the impact. Furthermore, the carbon fiber embedded in the polymer matrix results in resistive heating …

On Applications And Limitations Of One-Dimensional Capillarity Formulations For Media With Heterogeneous Wettability, T. M. Bucher, H. Vahedi Tafreshi

Mechanical and Nuclear Engineering Publications

Force-balance-based one-dimensional algebraic formulations that are often used in characterizing the capillarity of a multi-component system (e.g., predicting capillary height rise inporous media) are discussed. It is shown that such formulations fail to provide accurate predictions when the distribution of wetting (or non-wetting) surfaces is not homogeneous. A more general mathematical formulation is suggested and used to demonstrate that for media with heterogeneous wettability, hydrophilic (or hydrophobic) surfaces clustered in groups will have less contribution to the overall capillarity of the system.

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 …

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.

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 …

Multiphase Hydrodynamics In Steady And Pulse Jet Mixing Systems, Ibraheem R. Muhammad

Dissertations

The goal of the present study is to evaluate the mixing performance of jet mixers in both liquid and solid-liquid mixing processes. Jet mixers have been studied for decades for its uses in liquid blending and solid-liquid mixing applications. In solid suspension processes, jet mixers can be just as useful if not more useful than conventional impeller mixers. However, there is a lack of phenomenological models that exist. The erosion and subsequent suspension of solids beds, as well as the suspension of a low concentration of solid particles must be better understood. The specific objectives were to develop analytical, experimental …

Predicting The Crack Response For A Pipe With A Complex Crack, Robert George Lukess

Theses and Dissertations

Traditional flaw evaluation in the nuclear field uses conservative methods to predict maximum load carrying capacity for flaws in a given pipe. There is a need in the nuclear industry for more accurate estimates of the load carrying capacity of nuclear piping such that probabilistic tools can be used to predict the time to failure for various types of cracks. These more accurate estimates will allow the nuclear industry to repair flaws at a more appropriate time considering external factors such as costs and man-rem planning along with the flaw repair. Analysis of the maximum load carrying capacity of a …

Application Of Computational Fluid Dynamics Methods To Improve Thermal Hydraulic Code Analysis, Dennis Shannon Sentell, Jr.

Theses and Dissertations

A computational fluid dynamics code is used to model the primary natural circulation loop of a proposed small modular reactor for comparison to experimental data and best-estimate thermal-hydraulic code results. Recent advances in computational fluid dynamics code modeling capabilities make them attractive alternatives to the current conservative approach of coupled best-estimate thermal hydraulic codes and uncertainty evaluations. The results from a computational fluid dynamics analysis are benchmarked against the experimental test results of a 1:3 length, 1:254 volume, full pressure and full temperature scale small modular reactor during steady-state power operations and during a depressurization transient. A comparative evaluation of …

Evolution Of Microstructure Of Haynes 230 And Inconel 617 Under Mechanical Testing At High Temperatures, Kyle Hrutkay

Theses and Dissertations

Haynes 230 and Inconel 617 are austenitic nickel based superalloys, which are candidate structural materials for next generation high temperature nuclear reactors. High temperature deformation behavior of Haynes 230 and Inconel 617 have been investigated at the microstructural level in order to gain a better understanding of mechanical properties. Tensile tests were performed at strain rates ranging from 10-3-10-5 s-1 at room temperature, 600 °C, 800 °C and 950 °C. Subsequent microstructural analysis, including Scanning Electron Microscopy, Transmission Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, and X-Ray Diffraction were used to relate the microstructural evolution at high temperatures to that of room …

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 …

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. …

The Effect Of Gamma Radiation On Fibre Bragg Grating Sensors When Used As Radiation Dosimeters, Des Baccini

Theses : Honours

The effects of Gamma Radiation on Fibre Bragg Gratings (FBGs), when used as a radiation dosimeter, was proposed. The focus of this study centred on the FBG performance, and in particular the Bragg Wavelength Shift (BWS) whilst being exposed to ionizing radiation. Current research suggests that certain types of fibres manufactured by varying methods produce different results. The different responses to exposure from gamma irradiation between Germanium (Ge) doped optical fibres, with and without Hydrogen loading, along with the standard SMF-28 fibre with Hydrogen, were used and results noted and compared to previous work. The FBG’s in each fibre were …

The Study Of Alternate, Solid-Phase Fluorinating Agents For Use In Reactive Gas Recycle Of Used Nuclear Fuel, Dillon Inabinett

Theses and Dissertations

Surrogate oxides of the Used Nuclear Fuel (UNF) matrix were fluorinated using alternate, solid-phase fluorinating agents XeF2 and NH4HF2 to form volatile and non-volatile compounds and demonstrate the possibility of a chemical and thermal separations. A matrix of experiments was conducted at the milligram quantity scale using a Shimadzu DTG-60 TG/DTA installed at SRNL (Savannah River National Laboratory) for testing of all non-radioactive samples and a Netzsch STA 409 TGA installed in the laboratory at USC (University of South Carolina) for testing of all radioactive samples. The fluorination and subsequent volatilization potentials were analyzed by mixing excess fluorinating agent with …

Advanced Fuels Modeling: Evaluating The Steady-State Performance Of Carbide Fuel In Helium-Cooled Reactors Using Frapcon 3.4, Luke H. Hallman

Theses and Dissertations

Uranium carbide (UC) has long been considered a potential alternative to uranium dioxide (UO2) fuel, especially in the context of Gen IV gas-cooled reactors. It has shown promise because of its high uranium density, good irradiation stability, and especially high thermal conductivity. Despite its many benefits, UC is known to swell at a rate twice that of UO2. However, the swelling phenomenon is not well understood, and we are limited to a weak empirical understanding of the swelling mechanism.

One suggested cladding for UC is silicon carbide (SiC), a ceramic that demonstrates a number of desirable properties. Among them are …