Nuclear Engineering Commons^™

Cfd Analysis For Beyond Bubbly Gas-Liquid Two-Phase Flows In A Large Diameter Pipe, Sungje Hong

Doctoral Dissertations

"Due to the complexity of multiphase flow phenomena, numerical analysis for multiphase turbulent flow is not as reliable as single-phase computational fluid dynamics (CFD). A literature review has revealed that the current efforts on multiphase flow simulation have focused on small diameter channels under very restricted flow conditions and have been conducted without identifying some important procedures. To expand CFD applications to a wide range of two-phase flow conditions in large diameter channels, this study aims to validate the current CFD models for vertical concurrent air-water two-phase flow simulations beyond bubbly flows. First, a numerical model developed to describe dynamical …

3d Cfd Simulation Of A Bubble Column With Internals: Validation Of Interfacial Forces And Internal Effects For Local Gas Holdup Predictions, Hayder Al-Naseri, Joshua P. Schlegel, Muthanna H. Al-Dahhan

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

CFD Models (Turbulent Models and Interfacial Forces) Incorporated with the Population Balance Model (PBM) Have Been Validated, Azimuthally, with the Gamma-Ray-Computed Tomography (CT) Results to Address the Effect of the Presence of Internals with Different Arrangements and Diameters. the Superficial Gas Velocity Applied Was Varied from 0.05 to 0.45 M/s. the Results Exhibit the Capability to Predict the Hydrodynamics of the Bubble Column, Further Incorporating the Population Balance Model and Promoting the Prediction of Simulation in High Superficial Gas Velocity. the Effect of Internals Revealed that the Gas Holdup Was Significantly Enhanced in the Bubble Column's Wall Region, While the …

Small Modular Reactors, Joshua P. Schlegel, P. K. Bhowmik

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Small Modular Reactors (SMRs) have been a very promising development in nuclear power over the last two decades. SMRs are defined as nuclear reactors with a power output of less than 300MWe. This is in comparison to gigawatt-size reactors, which can have electrical output of 1000–1500MWe or more. This chapter will consist of two major sections. the first will be a detailed summary of the small modular reactor designs being proposed around the world. This section will focus on those that are the furthest along in their development but will also include some information about the wide variety of proposed …

The Role Of Generation Iv Nuclear Reactors In Decarbonising International Shipping : A Multi-Criteria Decision Making (Mcdm) Framework For Matching Potential Decarbonisation Pathways To Different Ship Types And Size, Claudianus David Kunze

World Maritime University Dissertations

No abstract provided.

Thermodynamic Assessment Of Chromium Corrosion In The Na-K-Mg-U(Iii, Iv) Chloride Salt, Jacob Allen Yingling

Theses and Dissertations

Thermodynamic descriptions of high-order molten chloride salt systems are essential for the development of fast molten salt reactor (MSR) technologies. However, a complete thermodynamic assessment of the essential Na-K-Mg-U(III)-U(IV) molten chloride salt with the most prevalent CrCl2 corrosion product has yet to be provided. This is remedied in the present work through application of the CALculation of PHAse Diagrams (CALPHAD) approach to the available thermodynamic data and new measurements that include differential scanning calorimetry (DSC) observations for previously unexplored two and three component chloride salt systems. Through these efforts, a unique approach was developed for the quantification of uncertainty in …

Reinforcement Of The Plasmon–Phonon Coupling In Α-Quartz Via Deposition Of Gold Nanoparticles In Etched Ion Tracks, Maria C. Garcia Toro, Miguel L. Crespillo, Jose Olivares, Joseph T. Graham

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

This study reports a large reinforcement of the plasmon–phonon coupling in alpha quartz achieved through the controlled deposition of gold nanoparticles into nano templates produced through chemical etching of ion tracks. Preferential agglomeration of nanoparticles within the etched ion tracks (nano wells) was observed in Scanning Electron Microscopy and Atomic Force Microscopy images. Raman characterization of quartz substrates with different nanoparticle concentrations revealed a relationship between the plasmon–phonon coupling intensity and nanoparticle concentration. Reinforcement of the plasmon–phonon coupling was observed as an increase in the Raman intensity with increasing concentration of deposited nanoparticles. The intensity initially increased linearly with nanoparticle …

Full Volume 13, Issue 1, Seyma Tufan

Space and Defense

No abstract provided.

Enabling Rapid Chemical Analysis Of Plutonium Alloys Via Machine Learning-Enhanced Atomic Spectroscopy Techniques, Ashwin P. Rao

Theses and Dissertations

Analytical atomic spectroscopy methods have the potential to provide solutions for rapid, high fidelity chemical analysis of plutonium alloys. Implementing these methods with advanced analytical techniques can help reduce the chemical analysis time needed for plutonium pit production, directly enabling the 80 pit-per-year by 2030 manufacturing goal outlined in the 2018 Nuclear Posture Review. Two commercial, handheld elemental analyzers were validated for potential in situ analysis of Pu. A handheld XRF device was able to detect gallium in a Pu surrogate matrix with a detection limit of 0.002 wt% and a mean error of 8%. A handheld LIBS device was …

A Numerical Thermal Analysis Of A Battery Pack In An Electric Motorbike Application, Mohammad Shahjalal, Tamanna Shams, Sadat Bin Hossain, Probir Kumar Roy, Arafat Alam Jion, Mominul Ahsan, Jahedul Islam Chowdhury, Md Rishad Ahmed, Syed B. Alam, Julfikar Haider

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Today, electric driven motorbikes (e-motorbikes) are facing multiple safety, functionality and operating challenges, particularly in hot climatic conditions. One of them is the increasing demand for efficient battery cooling to avoid the potential thermal stability concerns due to extreme temperatures and the conventional plastic enclosure of the battery pack. A reliable and efficient thermal design can be formulated by accommodating the battery within an appropriate battery housing supported by a cooling configuration. The proposed design includes a battery pack housing made of high conductive materials, such as copper (Cu) and aluminum (Al), with an adequate liquid cooling system. This study …

Computational Methods, Investigations, And Codes To Support Corrosion Experiments In Molten Lead And Transfer To Reactor Conditions, Khaled A. Talaat

Nuclear Engineering ETDs

Lead cooled fast reactors have many potential economic advantages over other Generation IV reactor designs due to the high boiling point of lead (~1750 °C) at atmospheric pressure and excellent neutronic properties which have made them attractive to the commercial energy sector in the recent years. They, however, remain hampered by challenges in cladding material compatibility with the heavy liquid metal coolant. A forced circulation loop was established at the University of New Mexico (“Lobo Lead Loop”) to prequalify materials for Versatile Test Reactor (VTR) testing and to improve the understanding of flow accelerated corrosion in molten lead environment. Corrosion …

Enhancements To Nuclear Thermal Propulsion Rockets, Kimberly Gonzalez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nuclear thermal rocket propulsion has been proposed as a highly efficient technology for space vehicles traveling from earth orbit to the moon, Mars, and other locations in the solar system. With twice the performance of a chemical rocket, nuclear thermal propulsion (NTP) uses the thrust produced by heating hydrogen gas within a thermal nuclear reactor where the exhaust is then passed through a de Laval nozzle to produce supersonic flow. NTP engines were the subject ofthe NERVA experiments at the Nevada Test Site in the 1970’s, and they produced a specific impulse of up to 900 seconds which is almost …

Modeling The Reactor Time-Dependent Delayed Particle Tail With Monte Carlo N-Particle (Mcnp) Version 6.2, Eli James Boland

Masters Theses

"Energy is deposited into experiment packages due to post-shutdown decay heat created from delayed particles. Modeling these delayed particles in a reactor assists researchers in quantifying the expected energy deposition sources to an experiment package before irradiation. This paper focuses on modeling the delayed particles in a reactor in MCNP6.2 by capturing a reactor as a source, converting this source capture to a source definition, applying appropriate physics such as activation and photonuclear interactions, and finally using proper tallies to create the expected delayed particle tail of a reactor.

To capture the source distribution, the FMESH capability within MCNP was …

Computational Models To Detect Radiation In Urban Environments: An Application Of Signal Processing Techniques And Neural Networks To Radiation Data Analysis, Jose Nicolas Gachancipa

Beyond: Undergraduate Research Journal

Radioactive sources, such as uranium-235, are nuclides that emit ionizing radiation, and which can be used to build nuclear weapons. In public areas, the presence of a radioactive nuclide can present a risk to the population, and therefore, it is imperative that threats are identified by radiological search and response teams in a timely and effective manner. In urban environments, such as densely populated cities, radioactive sources may be more difficult to detect, since background radiation produced by surrounding objects and structures (e.g., buildings, cars) can hinder the effective detection of unnatural radioactive material. This article presents a computational model …

Joining Of Candidate Materials For Lead-Cooled Fast Reactors, Brandon M. Bohanon

Nuclear Engineering ETDs

The lead-cooled fast reactor (LFR) is a fourth-generation reactor design characterized by high temperatures, neutron dosage, and highly corrosive and erosive environment due to high flow velocities. Therefore, materials testing must be performed to find structural and system components that withstand this harsh environment. These candidate alloys must have high-temperature creep strength, resistance to damage from fast-spectrum neutrons, and must grow protective oxide layers. FeCrAl alloys have been identified as possessing all these qualities, however, there are limitations due to erosion and the joining of these materials. In this work, mechanical and microstructural properties of base and conventionally joined FeCrAl-based …

The Effects Of A Power Iteration-Based K-Eigenvalue Solver For Various Subcritical Parameters And Calculations, Daniel H. Timmons

Nuclear Engineering ETDs

The need to simulate subcritical benchmark parameters quickly and accurately is becoming increasing important. When using Monte Carlo methods this is traditionally done using a fixed-source calculation where a particle and its progeny are tracked until their removal from the system. This method can be slow for near critical systems. The use of a k-eigenvalue solver could reduce the computational footprint and reduce the need to post process data.

This is done for four parameters from the ICSBEP benchmark values: R_1 , R_2 , M_L, and M_eff. These parameters are calculated in two new distinct ways. First, is directly …

First-Principles Study Of The Thermal Properties Of Zr2c And Zr2co, Yue Zhou, William Fahrenholtz, Joseph T. Graham, Gregory E. Hilmas

Materials Science and Engineering Faculty Research & Creative Works

First-principles calculations of lattice thermal conductivities and thermodynamic properties of Zr2C and Zr2CO were performed using the quasi-harmonic approximation. Oxygen in the lattice gives Zr2CO higher bonding strength than Zr2C. Thus, the mechanical properties of Zr2C are enhanced when the vacancies in its crystal structure are filled with oxygen. Among the critical parameters that determine the lattice thermal conductivity, Zr2C has significantly higher Grüneisen parameters, thus Zr2C has lower lattice thermal conductivity than Zr2CO. In addition, Zr2CO has a higher heat capacity and thermal expansion coefficient than Zr2C at most temperatures. These results indicate that the addition of oxygen has …

Nuclear Fuel Cycle: Safe Management Of Spent Nuclear Fuel, Robert L. Sindelar

Journal of the South Carolina Academy of Science

The aim for storage of spent nuclear fuel (SNF) either in wet or in dry storage systems is to ensure general safety objectives are met throughout a desired storage period. Staff at the Savannah River National Laboratory (SRNL), in collaborations with partners at other national laboratories, industry research organizations, and the University of South Carolina (UofSC), have performed materials aging testing and analyses, and have established nuclear materials aging management programs to support extended periods of safe storage of research reactor (RR) SNF and of commercial power reactor (PR) SNF pending ultimate disposal. Several example challenges include susceptibility of aluminum …

Simulation Of Thermal Radiation Transport In Stochastic Media With Nonlinear Temperature Dependence, Corey Michael Skinner

Nuclear Engineering ETDs

Nonlinear gray thermal radiation transport (TRT) in binary statistical mixtures is investigated through Implicit Monte Carlo (IMC) simulation on one-dimensional planar Markovian geometries and two dimensional approximate Markovian or Poisson-Box geometries. A stochastic geometry option was implemented in the Los Alamos National Laboratory Branson IMC solver which yielded benchmark solutions by simulating thermal radiation and material energy transport over a large number of instantiations of the geometry followed by ensemble averaging to obtain conditionally averaged radiation intensity and material temperatures. A chord length sampling method was also implemented based on a heuristic generalization of the Levermore-Pomraning homogenized medium model to …

Nuclear Energy As A Reliable And Safe Source Of Power Generation, Sarup Dhungana

Honors Theses

There is a high demand of energy for generating civil applicable power in the world and in the USA, correspondingly. The world has been consuming various sources to extract the power to meet its demands. Most of the power sources include renewable and non-renewable sources like fossil fuels, natural gas, coal, water, solar, wind, and nuclear power. Although most of these sources have many advantages in terms of their capacity and cost of production, nuclear power can be categorized as the emerging driving force in the United States and in the world for power generation, because of its reliability and …

Light Emission Of Self-Trapped Excitons From Ion Tracks In Silica Glass: Interplay Between Auger Recombination, Exciton Formation, Thermal Dissociation, And Hopping, Joseph T. Graham, Miguel L. Crespillo, Fernando Agulló-López, William J. Weber

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The initial luminescence yield of amorphous silica under ion irradiation has been studied at temperatures between 30 and 100 K, using swift ions of different masses and energies (3 MeV H, 3.5 MeV He, 19 MeV Si and 19 MeV Cl). The intensity of the 2.1 eV emission band, ascribed to the intrinsic recombination of self-trapped excitons (STEs), has been found to vary systematically with ion mass, energy and irradiation temperature. A detailed model has been developed to quantitatively describe those variations in terms of the competition between non-radiative Auger recombination, STE formation, STE thermal dissociation, and subsequent STE hopping …