Nuclear Engineering Commons^™

Development Of A Discrete Ordinates Code System For Unstructured Meshes Of Tetrahedral Cells, With Serial And Parallel Implementations, Rodney L. Miller

Theses and Dissertations

A numerically stable, accurate, and robust form of the exponential characteristic (EC) method, used to solve the time-independent linearized Boltzmann Transport Equation, is derived using direct affine coordinate transformations on unstructured meshes of tetrahedra. This quadrature, as well as the linear characteristic (LC) spatial quadrature, is implemented in our transport code, called TETRAN. This code solves multi-group neutral particle transport problems with anisotropic scattering and was parallelized using High Performance Fortran and angular domain decomposition. A new, parallel algorithm for updating the scattering source is introduced. The EC source and inflow flux coefficients are efficiently evaluated using Broyden's rootsolver, started …

Trends. The Ins And Outs Of Nuclear Nonproliferation: The Case Of Georgia, Ibpp Editor

International Bulletin of Political Psychology

The author discusses the strong case that can be made that the essence of all foreign policy matters involves the most basic of psychological boundaries: between the "me" and "not me".

When The "Soft" Sciences Become Hard: The Safety Of Canadian Nuclear Reactors, Ibpp Editor

International Bulletin of Political Psychology

The author discusses the ins-and-outs of the safety of Canadian nuclear reactors.

Creating Origen Models, Gregory D. Louden

Theses and Dissertations

The purpose of this study was to develop a methodology for creating problem dependent cross section libraries for ORIGEN (Oak Ridge Isotope Generation and Depletion Code). The Air Force Technical Applications Center (AFTAC) has a requirement to classify spent nuclear fuel. The ORIGEN codes provide generic models of commercial nuclear reactor designs that are not adequate for the detailed analysis required by AFTAC. After comparing the methods that ORIGEN2 an ORIGEN-S use to develop burnup dependent cross section libraries, the research focused on developing a methodology for creating new ORIGEN-S models. Models of the Ohio State University Research Reactor were …

Trends. The Cassini Mission To Saturn: Plutonium As Propaganda, Ibpp Editor

International Bulletin of Political Psychology

The author discusses the plutonium-carrying Cassini mission to Saturn.

Do Not As I Say And Not As I Do: The Problem Of Tritium, Ibpp Editor

International Bulletin of Political Psychology

The author discusses the manufacture and use of tritium for nuclear warheads.

Trends. Supercomputer Sales And Nuclear Proliferation: The Surrealist Top Ten, Ibpp Editor

International Bulletin of Political Psychology

The author discusses supercomputers in conjunction with nuclear weapons.

Physical And Managed Risk Of Nuclear Waste, Lennart Sjöberg, Britt-Marie Drottz-Sjöberg

RISK: Health, Safety & Environment (1990-2002)

The authors describe their work on the perceived risk of nuclear waste in Sweden. Three levels of waste were studied, and comparisons between the perceptions of the public, politicians and nuclear experts are made.

Book Review Of Alla Yaroshinskaya, Chernobyl: The Forbidden Truth, John M. Gleason

RISK: Health, Safety & Environment (1990-2002)

Review of the book: Alla Yaroshinskaya, Chernobyl: The Forbidden Truth (Michele Kahn & Julia Sallabank, trans. University of Nebraska Press 1995). Introduction, foreword, list of illustrations, photographs. ISBN 0-8032-4912-8. [136 pp. Cloth $25.00; Paper $10.00. 312 N. 14th Street, Lincoln NE 68588-0484.]

The Decision To Reactivate A First-Generation Soviet Nuclear Power Plant: Conceptual And Decision-Analytic Frameworks, John M. Gleason

RISK: Health, Safety & Environment (1990-2002)

Explores a variety of factors that led to reopening the Armenian Metsamor facility notwithstanding general agreement that this is unwarranted technologically.

Maximum Individual & Vicinity-Average Dose For A Geologic Repository Containing Radioactive Waste, Thomas H. Pigford

RISK: Health, Safety & Environment (1990-2002)

Explains the basis for his strong dissent to an NAS report on Yucca Mountain.

Academy Recommendations On The Proposed Yucca Mountain Waste Repository: Overview And Criticisms, Kristin S. Shrader-Frechette

RISK: Health, Safety & Environment (1990-2002)

Offers alternative criticism of the NAS report.

Spherical Harmonics - Finite Element Treatment Of Neutron Transport In Cylindrical Geometry, Hatem Khouaja, D. Ray Edwards, Nicholas Tsoulfanidis

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A variational spherical harmonics (DPN) method is used in conjunction with the finite element method to solve the transport of neutron beams. The method is developed for finite axisymmetric cylindrical geometry. In this model, the angular distribution along the path of neutron travel is separated into two sub-ranges of the forward and the backward moving particles. The system of the model equations is cast in terms of an even and an odd vector analogue to the even-parity transport technique. The finite element method is applied in space to solve the resulting coupled system of equations. A source-free cylinder with specified …

Thermalhydraulics Analysis Of The Unit-Cell Nuclear Light Bulb Rocket Engine, Vojislav Banjac

Nuclear Engineering ETDs

This dissertation presents a detailed thermalhydraulics analysis of the unit-cell derivative of the Nuclear Light Bulb (NLB) rocket engine. The NLB engine is a gas core nuclear rocket first proposed in the 1960's by the then-United Aircraft Research Laboratories (UARL); its unit-cell derivative consists of a low-temperature moderator/reflector as well as segmented propellant channels, both proposed with the intent of increasing the k_eff of the system.

The results of this work can be grouped into two major areas: (1) thermal and neutronics analysis of the engine, and (2) investigation of the feasibility of the engine over a wide range …

Effects Of Specimen Size Reduction On The Transition Curve Of The Charpy V-Notch Impact Test, Lonnie Eugene Schubert

Masters Theses

"This study was undertaken to correlate the impact properties of ASTM standard full size Charpy V-notch impact specimens to the impact properties of subsize specimens. An ASTM A533-B quenched and tempered plate steel was examined. The fine grained martensitic material had a coarse prior austenite grain size, which resulted in a low upper shelf energy for this material. Three sizes of specimens were included. Specimens were irradiated in the TRIGA Reactor Facility operated by the U. S. Geological Survey in Denver, Colorado, to 1 x 10¹⁹ n/cm² (E > 1 MeV) at 150°C (302°F). Unirradiated and irradiated specimens were …

Impact Of Nuclear Rocket Engine Design On Control Strategies, John A. Lambright

Nuclear Engineering ETDs

In a nuclear thermal rocket engine, the propellant gas can be varied independent of the peak chamber temperature. Startup and shutdown times can be varied over a wide range due to this uncoupling of the energy source from the working fluid. Therefore, in the early stages of nuclear rocket engine development. a study of the impact of the engine design on control strategies and systems was conducted. In order to define what is required in terms of engine thrusting times. this study focused on the thrust requirements for a Reusable Orbital Transfer Vehicle (R0TV).

Three nuclear rocket designs were used …

Agglomarate Formation During Drying Of Fine Powders, Alok Maskara

Nuclear Engineering ETDs

The effect of capillary pressure, solubility, and surface chemistry on agglomeration of silica and titania particles during drying was studied. Three batches of silica particles with diameter between 15 and 500 nm as well as titania particles with nominal diameter of 30 nm were used. Drying rate was varied by using both tray drying and spray drying. Aprotic solvents ranging in surface tension from 18 dynes/cm (hexane) to 72 dynes/cm (water), and mixtures of water/propanol and water/butanol ranging in surface tension from 35 dynes/cm to 72 dynes/cm, were used to vary the surface tension of the solvent. Water between pH …

Total Ionizing Dose Effects In Mosfet Devices At 77 K, Kevin J. Daul

Theses and Dissertations

Total ionizing dose effects on thermal oxide and reoxidized nitrided oxide (RNO) MOSFET devices at 77 K were studied. The MOSFETs were immersed in liquid nitrogen and irradiated, using a ⁶⁰Co source, up to 1 Mrad(Si) at a dose rate of 107 rads(Si)-sec. Drain current-gate voltage characteristics were obtained and used to determine threshold voltage and transconductance. At 77 K the subthreshold slopes indicated no observed buildup of interface states in any of the transistors. Furthermore, all transistors experienced very little change in the transconductance. Typical negative shifts in threshold voltage as dose increased were observed in all of …

Long-Term Effects Of Neutron Absorber And Fuel Matrix Corrosion On Criticality, William Culbreth, P. Zielinski

Mechanical Engineering Faculty Research

Proposed waste package designs will require the addition of neutron absorbing material to prevent the possibility of a sustained chain reaction occurring in the fuel in the event of water intrusion. Due to the low corrosion rates of the fuel matrix and the Zircaloy cladding, there is a possibility that the neutron absorbing material will corrode and leak from the waste container long before the subsequent release of fuel matrix material. An analysis of the release of fuel matrix and neutron absorber material based on a probabilistic model was conducted and the results were used to prepare input to KENO-V, …

Shock Wave Interaction With L-Shaped Structures, Richard C. Miller

Theses and Dissertations

This study investigated the interaction of shock waves with L-shaped structures using the CTH hydrodynamics code developed by Sandia National Laboratories. Computer models of shock waves traveling through air were developed using techniques similar to shock tube experiments. Models of L-shaped buildings were used to determine overpressures achieved by the reflecting shock versus angle of incidence of the shock front. An L-shaped building model rotated 45 degrees to the planar shock front produced the highest reflected overpressure of 9.73 atmospheres in the corner joining the two wings, a value 9.5 times the incident overpressure of 1.02 atmospheres. The same L-shaped …

Excited Atomic Bromine Energy Transfer And Quenching Mechanisms, Ray O. Johnson

Theses and Dissertations

Pulsed and steady-state photolysis experiments have been conducted to determine the rate coefficients for collisional deactivation of the spin-orbit excited state of atomic bromine, Br(²p_1/2). Pulsed lifetime studies for quenching by Br₂ and CO₂, established absolute rate coefficients at room temperature of k_Br2 = 1.2 ± 0.1 x 10^-12 and k_CO2 = 1.5 ± 0.2 x 10^-11 cm³/molecule-s. Steady-state photolysis methods were used to determine the quenching rates for the rare gases, N₂, 0₂, H₂, D₂, NO, …

Linear Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport On Arbitrary Triangles, Dennis J. Miller

Theses and Dissertations

A new discrete ordinates spatial quadrature for arbitrary triangular cells is derived and compared to its rectangular cell linear characteristic counterpart. The triangular mesh is more flexible, allowing curved surfaces and off-axis angles to be approximated with many fewer spatial cells. The triangle method is consistently more accurate on example problems tested here. Arbitrary orientation and size of the triangles allow non-patterned meshes to be developed which appears to ameliorate numerical diffusion. The triangle linear characteristic quadrature converges at nearly the same rate as rectangular Linear characteristic on Lathrop's problem. Mesh sensitivity measurements show large variations in triangle vertex locations …

Mitigation Of Shock Waves In A Cylindrical Tunnel By Foam, Grant W. Fondaw

Theses and Dissertations

This study investigated the effectiveness of foam linings in mitigating shock waves in tunnels. A polyurethane foam liner of varying density, crush strength and thickness was modeled inside a 1 meter radius tunnel and an explosion of 1.25 kg of plastic explosive was simulated. Using CTH, an Eulerian- Lagrangian hydrodynamics code from Sandia National Laboratories, the overpressures were computed and compared graphically to determine the effect of varying each foam parameter. The walls of the tunnel consisted of a perfectly reflecting boundary, and in some cases, a foam liner. Low density foam provided the most shock attenuation. with a 20 …

Analysis Of Topaz Ii And Space-R Space Nuclear Power Plants Using A Modified Thermionic Model, Otto D. Habedank

Theses and Dissertations

Models based on the TDS thermionic diode model were developed for TOPAZ II and SPACER nuclear power systems. Several parameter studies were conducted with the TOPAZ II model. These determined system performance and efficiency while varying the following: (1) Coolant flow inlet temperatures. (2) Rate of coolant temperature change. (3) Power profile of the core. (4) Cesium reservoir temperature. Analysis of results indicate the model accurately represented the TOPAZ II system, underestimating published data by 10%. Coolant flow studies indicate that raising coolant temperatures up to 100 K higher increases system power by up to 5%. Additional increases in temperature …

Amplification Of Shock Overpressure By Reflection Within Concave Corners, John E. Loftis

Theses and Dissertations

In this study, CTH, a production hydrodynamics code developed and provided by Sandia National Laboratories. modeled the interaction of a shock wave with tall V-shaped buildings with various wall lengths and vertex angles. The purpose of this study was to determine the degree to which the length and vertex angle affect the peak overpressure at the vertex. CTH performed two- dimensional Eulerian-Lagrangian computations to obtain solutions of this problem. The models were cast in two-dimensional rectangular geometry on a horizontal plane because of the computational costs of three-dimensional calculations. This geometry simulates tall buildings exposed to a tall Mach stem …

Afitbunki: A Modified Iterative Code To Unfold Neutron Spectra From Bonner Sphere Detector Data, Sean C. Miller

Theses and Dissertations

The neutron spectrum unfolding code BUNKI, developed at the Naval Research Laboratory in 1983, was modified to incorporate a finer energy group structure, seven initial-guess spectra, and new dose conversion factors. The modified code, AFITBUNKI, unfolds spectra into 54 energy groups between 10^-7 and 14.92 MeV. The code calculates fluence, absorbed dose, percent of effective dose equivalent, and percent of ambient dose equivalent as a function of neutron energy. Additionally, AFITBUNKI calculates total energy-integrated fluence (Φ), absorbed dose (D), dose equivalent (H), effective quality factor (Q), ambient dose (D*), both ICRP Publication 26- and ICRP Publication 60-based ambient dose …

Construction And Testing Of A Neutron And Gamma Spectrometry System Using Pulse Shape Discrimination With An Organic Scintillator, Robert S. Pope

Theses and Dissertations

The goal of this thesis was to construct and test a neutron detector to measure the energy spectrum of 1 to 14-MeV neutrons in the presence of gammas. A spectrometer based on the process of pulse shape discrimination (PSD) was constructed, in which the scintillator NE-213 was used. The primary neutron/ gamma sources used were 78-mCi and 4.7-Ci ²³⁹PuBe sources, while 4.7-µCi and 97.6-µCi ²²Na gamma sources were used for energy calibration and additional testing of the detector. Proton recoil spectra and Compton electron spectra were unfolded with the neutron and gamma unfolding code FORIST to generate the …

Identification Of Significant Outliers In Time Series Data, Keri L. Robinson

Theses and Dissertations

This thesis examines the feasibility of using least median of squares (LMS) procedure applied to a reweighted least squares (RLS) autoregression model to identify significant outliers in time series data. The time series were analyzed for data points that were outliers. In order to perform detailed analysis on an outlier. the analyst must be able to determine that an outlier data point is significantly different from normally distributed data. This thesis examines a new method for identifying these outliers. Data from the field were characterized and fit with time series models using an autoregressive reweighted least squares routine (ARRLS) derived …

Gamma Dose To A Fetus From Internal And External Sources, Lisa Stiles

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this study was to use the QAD computer code to calculate the dose received by a fetus from external and internal sources to which the mother is exposed. The changes in Chapter 10, part 20 of the Code of Federal Regulations that will be put into effect January 1, 1994, will require that radiation doses be reported not only for the whole body but to specific organs and the fetus as well. Fortunately, the computer program QAD can provide health physicists and other persons responsible for monitoring radiation exposure of individuals with an accurate, easy to use …

Using Modulated Beam Mass Spectrometry Techniques To Determine Hydrogen Levels In Single Crystal And Etched Single Crystal Silicon, Gregory J. Teets

Opportunities for Undergraduate Research Experience Program (OURE)

Silicon is an important element that has many applications ranging from semiconductors to solar cells. The quantity, diffusion, and bonding of hydrogen atoms in the silicon can play an important role in the electrical characteristics of single crystal and etched single crystal silicon. The hydrogen bonds to the impurities and to the dangling bonds in the silicon and reduces current leakage and improves performance [1-4]. Until now hydrogen bonding data has been extrapolated from related studies to determine hydrogen evolution temperatures from the silicon. Abrefah, Olander, et al. [1] studied deuterium evolution from silicon where the deuterium had been implanted …