Nuclear Engineering Commons^™

Radiation Tailored Polymers For Detectors, Adhesive-Coatings And Other Industrial Uses, Anna M. Earley, Alex Bakken, Rusi P. Taleyarkhan

The Summer Undergraduate Research Fellowship (SURF) Symposium

The ever growing importance of humans to depend on renewable resources has shifted the focus of consumers, producers, and even politicians to more sustainable answers. Furthermore, pressure on the oil and natural gas industry has elevated the status of biopolymers in this regard. Polylactic acid (PLA) is unique polymer that offers unique abilities for tailored property derivation; thereby, enabling one to replace many engineered polymers and provide a sustainable solution as a nontoxic renewable resource. As a bioplastic, the tailoring of PLA under various conditions is important to the application and integration into current industry uses. After irradiating high molecular …

Temperature Dependent Surface Modification Of Tungsten Exposed To High-Flux Low-Energy Helium Ion Irradiation, Antony Q. Damico, Jitendra K. Tripathi, Theodore J. Novakowski, Gennady Miloshevsky, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nuclear fusion is a great potential energy source that can provide a relatively safe and clean limitless supply of energy using hydrogen isotopes as fuel material. ITER (international thermonuclear experimental reactor) is the world first fusion reactor currently being built in France. Tungsten (W) is a prime candidate material as plasma facing component (PFC) due to its excellent mechanical properties, high melting point, and low erosion rate. However, W undergoes a severe surface morphology change when exposed to helium ion (He⁺) bombardment under fusion conditions. It forms nanoscopic fiber-form structures, i.e., fuzz on the surface. Fuzz is brittle …

Tfit Modeling Of Wave Propagation For Flow Excursion, Brachston Grubbs, Krishna Chetty, Martin Bertodano

The Summer Undergraduate Research Fellowship (SURF) Symposium

In the nuclear power industry, the Two-Fluid Model (TFM) is mainly used in the simulation of Loss of Coolant Accident (LOCA). The Two-Fluid Model is a wave mechanics formulation that may also be used to analytically perform stability analysis, which requires numerous assumptions and simplifications. This project aimed to advance the TFIT-TFM simulations in the modeling of the flow excursion instability. By using the TFIT computational code, simulation results can be obtained without the need for assumptions and simplifications. In this project, a simulation was performed to verify the nonlinear wave propagation capability of TFIT. During the verification process, the …

Modeling Of Ion/Target Interactions In Plasma Facing Components Of Fusion Reactor, Nicole Neto Godry Farias, Tatyana Sizyuk, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nuclear fusion is a promising source of clean energy that can be one of the key future suppliers of the world’s increasing power demand. One of today’s main challenges faced by scientists and engineers regarding nuclear reactors is to design plasma-facing components (PFCs) that can withstand extreme conditions of temperature, pressure, and ions/particles irradiation. Material evolution and damage of PFCs are strongly related to the bombardment and diffusion processes of ions resulting from fusion fuel, i.e., deuterium and tritium and reaction products, i.e., helium. However, work is still needed in order to understand fuel diffusion in the presence of helium …

Computer Modeling Of Graphene Field Effect Transistors, Drew M. Ryan, Robert S. Bean

The Summer Undergraduate Research Fellowship (SURF) Symposium

Graphene has been the centerpiece of numerous research projects since its discovery in 2004, greatly due to its multitude of unique properties. Its variable conductivity, relative strength, and electron mobility make graphene a prime candidate for applications in the field of radiation detection. While work has been performed in the past on testing radiation detection using graphene using Graphene Field Effect Transistors (GFET), due to its limited size, fabricating GFETs can be tedious and costly. Therefore, a need arose for a way to test potential GFET designs without the cost and limitations of fabricating GFETs for each test iteration. Using …

Fluence Dependent Surface Modification On Tungsten Coatings Using Low Energy Helium Ion Irradiation At Elevated Temperatures, Cheng Ji, Jitendra K. Tripathi, Theodore J. Novakowski, Valeryi Sizyuk, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nuclear fusion is the most promising renewable energy source for the near future. It can provide a large amount of energy using a very small amount of fuel, as compared with that of the coal, oil, or nuclear fission. The chain reaction in nuclear fusion produces the energy and fuel, from hydrogen isotopes available in see water. Tungsten (W) is a leading candidate material for the plasma-facing component (PFC) in nuclear fusion reactors such as ITER (international thermonuclear experimental reactor), because of its high melting point, high yield strength, low erosion and low hydrogen isotope retention. Recent studies showed deeply …

X-Ray Fluorescence For Quantification Of Lead And Strontium In Vivo, Aaron James Specht

Open Access Dissertations

Lead (Pb) is a toxicant well known for its effects on almost every organ system in the body. Pb use in industry has declined since removal of Pb from gasoline, but many developing countries still have significant use of Pb. Exposure to Pb has been linked with diseases causing neurodegeneration and thus have lasting effects long after the initial exposure. Another metal, strontium (Sr), has been linked with bone disease in particular situations and shown to have uses in treating osteoporosis as a supplement. However, there are no studies of the effects of Sr using a meaningful biomarker. The most …

Thermoelectric Half-Heuslers: Synthesis, Processing, And Performance, Joseph Robert Croteau

Boise State University Theses and Dissertations

Thermoelectric half-Heusler compounds have potential to convert the heat wasted from industrial and transportation processes to useful electricity. Among the highest performing half-Heusler compounds are nano-structured bulk materials which have been arc-melted, pulverized into a nano-powder, and sintered by DC-hot press. High performing n- and p-type half-Heusler compounds with nominal composition of Hf_0.25Zr_0.75NiSn_0.99Sb_0.01 and Nb_0.75Ti_0.25FeSb, respectively, have been provided to us in both dense and powder form by our collaborators at the University of Houston. We consolidate these powders by SPS, refine these powders to improve both particle size …

The Impact Of The State-Level Concept On “Newcomers”: A Case Study Of The Kingdom Of Saudi Arabia, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The International Atomic Energy Agency’s (IAEA) latest reports indicate a growing number of states (newcomers) considering the deployment of nuclear energy programs. In developing nuclear infrastructure, newcomers have to employ the prevailing standards to deploy the nuclear program in a secure, safe, and sustainable manner. State-Level Concept (SLC) refers to a comprehensive approach that uses information about a state’s nuclear facilities and capabilities to implement safeguards within the scope of the state’s safeguards agreement. SLC focuses on strengthening the effectiveness and improving the efficiency of the safeguards system considering the State as whole. SLC has been implemented in 53 states, …

Thin Film Alsb Carrier Transport Properties And Room Temperature Radiation Response, Erin Vaughan

Nuclear Engineering ETDs

Theoretical predictions for AlSb material properties have not been realized using bulk growth methods. This research was motivated by advances in molecular beam epitaxial (MBE) growth technology to produce high-quality thin-film AlSb for the purpose of evaluating transport properties and suitability for radiation detection. Simulations using MCNP5 were performed to benchmark an existing silicon surface barrier detector and to predict ideal AlSb detector behavior, with the finding that AlSb should have improved detection efficiency due to the larger atomic number of Sb compared with Si. GaSb diodes were fabricated by both homoepitaxial MBE and ion implantation methods in order to …

Integrated Microsphere Whispering Gallery Mode Probe For Highly Sensitive Refractive Index Measurement, Hanzheng Wang, Lei Yuan, Cheol-Woon Kim, Jie Huang, Xinwei Lan, Hai Xiao

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

We report an integrated whispering gallery mode microresonator-based sensor probe for refractive index sensing. The probe was made by sealing a borosilicate glass microsphere into a thin-wall glass capillary pigtailed with a multimode optical fiber. The intensities of the resonant peaks were found decreasing exponentially (linearly in a log scale) with the increasing refractive index of the medium surrounding the capillary. The sensing capability of the integrated probe was tested using sucrose solutions of different concentrations and the resolution was estimated to be about 2.5 x 10^-5 in the index range of 1.3458 to 1.3847. The integrated sensor probe …

Cyclotron Production And Biomedical Imaging Applications Of The Pet Isotope Manganese-52, Andrew Lake Wooten

McKelvey School of Engineering Graduate Student Theses & Dissertations

Manganese is an important element for biomedical research because of its roles as an essential micronutrient and as a neurotoxin from chronic elevated exposure, as well as the role of manganese(II) as a paramagnetic core for contrast agents in T1-weighted magnetic resonance imaging (MRI). Using a radiotracer of manganese provides excellent sensitivity for studying these phenomena, but only 52Mn met the criteria for our experiments: (1) a half-life (t1/2=5.6 days) that was long enough to examine timepoints over several days, (2) a half-life that was short enough to emit sufficient counts for a realistic scan time, and (3) emitted radiation …

Mcnp6 Computational-Based Sensitivity Propagation Analysis Of Continuous Neutron Cross-Sections Using The Godiva (Hmf-001) And The Godiver (Hmf-004) Benchmark Criticality Study Cases, Lawrence James Lakeotes

UNLV Theses, Dissertations, Professional Papers, and Capstones

There has been a reduction in funding for theoretical and applied research for improving the nation's database of continuous neutron cross-sections at BNL-NNDC. From 1940 through the late 1980s, research and applied development produced volumes of reliable neutron continuous cross-sections for many isotopes. Currently, the cross-section work has been mainly computational. The focus of this research is mainly centered on the requirements for improving thermal cross-sections to support reactor operations and fuel storage. The research efforts will also helpfully aid in the fast fission spectrum in order to support fast reactor designs for improving safety analysis and feedback coefficients.

This …

Neutron-Gamma Discrimination In Elpasolite Scintillator Detector, Brittany Morgan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Existing nuclear stockpiles and weapons-making capabilities imperil the global community. Current nonproliferation efforts involve the research and development of newer, more efficient detection systems that can be deployed for the interdiction and monitoring of special nuclear materials (SNM). Spontaneous and induced fission events in SNM produce neutrons and gamma rays, which can be detected and analyzed, in particular, using scintillator detectors. Various electronic data acquisition systems and data analysis methods have been employed to record and characterize neutron and photon signatures. The goal of this thesis is to develop a new method of discrimination between neutrons and photons in the …

Investigation Of 186Re Via Radiative Thermal-Neutron Capture On 185Re, David A. Matters, Andrew G. Lerch, A. M. Hurst, L. Szentmiklosi, J. J. Carroll, B. Detwiler, Zs. Revay, John W. Mcclory, Stephen R. Mchale, R. B. Firestone, B. W. Sleaford, M. Krticka, T. Belgya

Faculty Publications

Partial ��-ray production cross sections and the total radiative thermal-neutron capture cross section for the ¹⁸⁵Re(n,��)¹⁸⁶Re reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched ¹⁸⁵Re target. The ¹⁸⁶Re cross sections were standardized using well-known ³⁵Cl(n,��)³⁶Cl cross sections from irradiation of a stoichiometric ^natReCl₃ target. The resulting cross sections for transitions feeding the ¹⁸⁶Re ground state from low-lying levels below a cutoff energy of E_c=746keV were combined with a modeled probability of ground-state feeding from levels above E …

Cosmic Ray Muons For Spent Nuclear Fuel Monitoring, Stylianos Chatzidakis

Open Access Dissertations

There is a steady increase in the volume of spent nuclear fuel stored on-site (at reactor) as currently there is no permanent disposal option. No alternative disposal path is available and storage of spent nuclear fuel in dry storage containers is anticipated for the near future. In this dissertation, a capability to monitor spent nuclear fuel stored within dry casks using cosmic ray muons is developed. The motivation stems from the need to investigate whether the stored content agrees with facility declarations to allow proliferation detection and international treaty verification. Cosmic ray muons are charged particles generated naturally in the …

Nanoscale Phonon Thermal Conductivity Via Molecular Dynamics, Jonathan M. Dunn

Open Access Theses

Molecular dynamics (MD) simulations provide a useful and simple means of calculating the nanoscale thermal properties of materials, which requires special analysis since the thermal properties of materials change when their dimensions reach the nanoscale. In this research, MD is used to investigate the nanoscale phonon thermal transport of materials that are attracting much interest in the areas of materials science and nuclear physics. In order to evaluate two distinct methods of calculating the thermal conductivity of materials using MD, the simulation methods are first applied to Si. Once an understanding of each simulation method is established, they are then …

Method To Fabricate Portable Electron Source Based On Nitrogen Incorporated Ultrananocrystalline Diamond (N-Uncd), Anirudha V. Sumant, Ralu Divan, Chrystian M. Posado, Carlos Henry Castano Giraldo, Edwin J. Grant, Hyoung-Koo Lee

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A source cold cathode field emission array (FEA) source based on ultra-nanocrystalline diamond (UNCD) field emitters. This system was constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation a flat-panel source can be used in tomography, radiography, or tomosynthesis. Furthermore, the unit can be used as a portable electron or X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube “forest” (CNT) cathodes. Furthermore, UNCDs have better mechanical …

Neutron Versus Gamma Radiation Effects On Ytterbium-Doped Optical Fibers, Olivia M. Borman

Theses and Dissertations

Multimode ytterbium-doped optical fibers (YDFs) are increasingly utilized in military applications involving fiber lasers and amplifiers. YDFs were irradiated with three different radiation sources (neutron, gamma, and mixed gamma/neutron) in order to determine the independent effects that gamma and neutron radiation have on the fibers. The transmission spectra of the fibers were measured during each irradiation and the spectral shapes and attenuation were compared at similar doses. Comparisons of the spectra showed that gamma radiation results in increased attenuation over the 550-975 nm wavelengths. Fast neutrons were found to contribute to increased attenuation near 500 nm. Neutron radiation also caused …

Radiation Response From A Novel Uo2 Crystal, Stephan A. Varga

Theses and Dissertations

The radiation response of a novel, single-crystalline UO2 sample was analyzed using several types of radiation. The crystal was exposed to alpha, gamma, and neutron radiation under various environmental conditions and the electronic response of the crystal was measured using a pulse shape discrimination algorithm. The distributions of pulse amplitude (Vmax) and pulse decay times (τ) were used to compare the output. This research revealed that the crystal radiation response is exceptionally sensitive to surface conditions, specifically humidity, which tends to alter the time dependent currents resulting from the radiation interactions. The pulse τ can be made to …