Nuclear Engineering Commons^™

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 …

Conceptual Design Of The Modular Transuranic Shipping Cask Mts-54, Vojislav Banjac

Nuclear Engineering ETDs

The storage, transportation, and disposal of radioactive waste has become a problem of immense proportions in the United States. This Thesis focuses on the transportation of defense transuranic (TRU) waste to the Waste Isolation Pilot Plant (WIPP) repository near Carlsbad, New Mexico. The objective of the cask conceptual design was based on the following:

• Taking into account the latest available data on TRU waste drum mass, investigate the possibility of increased drum capacity per shipment over the current design;
• Present a new TRU cask design with increased drum capacity and the potential for transporting both Contact-handled (CH and Remote-handled (RH) …

Coupled Radiation Transport / Thermal Analysis Of The Radiation Shield For A Space Nuclear Retractor, William John Barattino

Nuclear Engineering ETDs

The renewed interest of conducting operations in space has given rise to re-establishment of space reactor systems development. The current SP-100 program is focussing on design of a 100 kW nuclear e reactor for space application. This research project investigated the coupling between radiation transport, energy deposition, and temperature distribution for a variety of space reactor shield configurations. The basic shield design consisted of tungsten [W], and natural lithium hydride either cast or pressed into a stainless steel matrix [LiH(Nat)].

For a nuclear reactor operating at a power level of 1.66 MW_th, temperature feedback effects on energy deposition …

Film Boiling Destabilization From Hydrodynamic And Thermodynamic Considerations, Fred Samuel Gunnerson

Nuclear Engineering ETDs

An analytical method is presented for predicting, from first principles, the minimum heater temperature and heat transfer rate at the onset of film boiling for spherical and ·flat plate heaters in saturated and subcooled liquids. Within the analysis, consideration is given to the two types of film boiling, they are:

(1) Pool film boiling where the entire heater is submerged within the boiling liquid, and

(2) Leidenfrost film boiling where a droplet of liquid boil s above a horizontal plate heater.

The Effect Of Volatile Fission Products On Fuel Motion In Nuclear Fuel Elements, Paul Sasa

Nuclear Engineering ETDs

Stringent licensing procedures for commercial nuclear reactor operation require an in-depth analysis of the phenomena associated with postulated reactor core overheating accidents. One aspect of nuclear reactor safety assessment is a prediction of fuel behavior associated with such postulated overheating events, which includes an assessment of the role of fission product inventory contained within irradiated fuel elements on fuel relocation potential. In general the gaseous fission product, such as Xenon and Krypton, have been considered the most likely candidates for fuel relocation due to gas dissolution from the fuel matrix and bubble expansion during fuel overheating; thus, such gaseous fission …

A System For Detecting Neutrons In The Harsh Radiation Environment Of A Relativistic Electron Beam, Lyle Wayne Kruse

Nuclear Engineering ETDs

Newly developed detectors and procedures allow measurement of neutron yield and energy in the harsh radiation environment of a relativistic electron beam source. A new photomultiplier tube design and special gating methods provide the basis for novel time-of-flight and total-yield detectors. The technique of activation analysis is expanded to provide a neutron energy spectrometer. There is a demonstrated potential in the use of the integrated system as a valuable diagnostic tool to study particle-beam fusion, intense ion-beam interactions, and pulsed neutron sources for simulating weapons effects. A physical lower limit of 10⁸ neutrons into 4π is established for accurate …

Improvement To The Solution Of Stefan-Like Freezing And Melting Problems, With Application To Lmfbr Safety Analysis, Mohamed Shafik El-Genk

Nuclear Engineering ETDs

This work involves development of improvements to two analytical methods to predict the instantaneous position of the moving phase-change front in one-dimensional Stefan-like problems. These techniques, the refined integral heat balance and the upper and lower bounds averaging methods, are useful in practical applications for reactor safety analysis, under hypothesized conditions leading to molten fuel relocation problems. With such applications in mind, the two methods are applied to four different one-dimensional problems which involve change-of­phase, with or without a convective boundary condition at the moving front. Comparison with the exact solution has been presented whenever possible; ultimately, all solutions have …

Vacuum-Freezing Vapor-Desublimation High Pressure Ice-Melting Process For Water Desalination, Ting-Chuan Chung

Nuclear Engineering ETDs

The present thesis study makes a preliminary technical feasibility study and a preliminary economic study of the Vacuum-Freezing Vapor-Desublimation High Pressure Ice-melting Process that was first introduced by C. Y. Cheng and W. Cheng. In the study, the processing steps are divided up into several key unit operations. Some of these key unit operations are similar to some operations in existing vacuum freezing processes and have already been studied extensively. Some key operations are, however, unique to the process under study. The feasibility study is made by borrowing information for the unit operations that have already been studied in connection …

Effective Equation Of State Measurements On Uranium Dioxide, Kenneth Orvis Reil

Nuclear Engineering ETDs

The safety analysis of Liquid Metal Fast Breeder Reactor (LMFBR) systems requires knowledge of the vapor pressure of reactor fuels up to 6000 K. A new technique was developed to obtain experimental vapor pressure data for reactor fuel materials at high temperatures and pressures. Fuel samples are pulse fission heated in the Annular Core Pulse Reactor (ACPR) at heating rates comparable to those anticipated during a severe LMFBR transient. The vapor of reactor fuels may contain several dissociated fuel species, volatile fission products, and/or fission gas. The evo­lution of that pressure may be time or rate dependent. For these reasons, …

Axial Xenon Redistribution And Power Shaping In Large Pressurized Water Reactors, Henrique F. V. A. Machado Jorge

Nuclear Engineering ETDs

The reactor described herein is aimed at developing an accurate physical model for axial power shaping studies in pressurized water reactors of the current generation. The model is also intended for numerical studies on: (1) reactor load-follow capability throughout a fuel loading lifetime; and (2) burnup dependence of the reactor stability against axial xenon oscillations. Accordingly, a proper account of the concerned physical phenomenology was sought. The results reported herein solely concern methods development and assessment.

A one-dimensional (axial) core geometrical model, coupled with

fuel temperature-and moderator coolant thermal-hydraulics-feedback was assembled. Algorithms for computing the feedback effects were developed and …

An Examination Of Thermal Stress As A Mechanism For Cladding Failure In A Hypothetical Lmrbr Transiet, Douglas Wakerfield Croucher

Nuclear Engineering ETDs

Stainless steel clad uranium dioxide fuel pellets were pulse irradiated in the Annular Core Pulse Reactor to evaluate thermal stress as a contributing mechanism for cladding failure in hypothetical LMFBR transients. The 6.2 mm diameter UO2 fuel pellets, with enrichments up to 25 w/o 235UO2, were helium bonded to 0.381 mm thick Type-316 stainless steel cladding and were irradiated in a helium environment with reactor pulses having initial periods as short as 1.5 milliseconds. In experiments conducted elsewhere with longer initial periods, the primary fuel failure mechanisms observed were differential fuel-cladding thermal expansion, intragranular fission-gas-induced fuel swelling, transient fission gas …

Safeguards Considerations For A Htgr Nuclear Fuel Cycle, Philip G. Johnson

Nuclear Engineering ETDs

Given that the prime objective of safeguards for special nuclear materials (SNM) is nonproliferation of nuclear weapons, it is logical that safeguards priorities should be commensurate with the relative suitabilities of the various SNM forms in existence for application in nuclear explosives. The SNM forms in each reactor fuel cycle, for example, should be screened and ordered according to their relative suitabilities for such misapplication. Significant considerations in assigning protection priorities include the relative suitabilities based on materials characteristics, inherent protection features of the mateerials or the processing of the SNM forms, the quantities of these materials in existence, and …

A Prompt D-D Neutron Calibration Of A Plastic Scintillator Detector, Dal H. Jensen

Nuclear Engineering ETDs

ABSTRACT

A new approach to the measurement of the neutron yield of low intensity (~ 2 x 10 neutrons/pulse) 0-0 neutron generators in a single pulse is described. A cylindrical (20.32 cm radius by 20.32 cm height) scin­tillator of Pilot-Bis optically coupled to a Phillips 57AVP photomulti­plier with a 20 cm diameter photocathode. The light pulse resulting from the neutron burst is fed into a voltage integrator calibrated in neutrons/ count.

The initial calibration of the stable neutron generator used in the scintillator calibration was performed using a silver activation detector (PT-502) designed by LASL. The data obtained for the …

Methods For Calculating Energy Deposition Using Coupled Neutron-Gamma Ray Transport, Lewis Douglas Rigdon

Nuclear Engineering ETDs

In radiation damage problems, it is desirable to know not only the neutron and gamma ray fluxes but also the energy deposition due to those fluxes. Following the recent availability of coupled neutron-gamma ray, multigroup-multitable cross sections and associated fluence-to-KERMA factors, an automated method has been developed for obtaining the energy deposition in a material region due to local neutron and gamma ray fluxes. Cross section sets which combine neutron and photon transport as well as a production matrix for neutron-induced gamma rays are used in the transport calculation. Thus in one discrete ordinates transport calculation, the energy deposition from …

Explosive Electron Emission And The Characteristics Of High-Current Electron Flow, Robert Kelley Parker

Nuclear Engineering ETDs

Within the past several years, an increasing effort has been concen­trated on the application of high-current, relativistic electron beams to the problem of controlled thermonuclear fusion. Initially, this effort had been impeded by limitations in the high-voltage and pulsed-power technology required to develop pulsed, high-power electron accelerators. These technologies have been developed to a level where powers on the order of 10¹³ watts are now available for time durations of approximately 100 nanoseconds. With the initial limitations removed, the emphasis has more recently been centered on controlling and concentrating these beams to achieve the parameters necessary for fusion experimentation. …

Elastic-Plastic Poisson's Ratio Of Borsic-Reinforced Aluminium Composites, Ronald Edward Allred

Nuclear Engineering ETDs

Poisson's ratio as a function of tensile strain has been examined for four volume fractions of unidirectional Borsic-reinforced aluminum composites. Linear relationships were found between Poisson's ratio and fiber volume fraction during Stage I (elastic filaments-elastic matrix) and Stage II (elastic filaments-plastic matrix) deformation which confirms that rule-of-mixtures equations may be used to predict Poisson's ratios for metal-matrix composites. These equations must be used with care, however, due to differences in the Poisson's ratio behavior of the components of the composite when tested alone and in situ in the composite. These differences are attributed to the triaxial stress field generated …

The Effect Of Porosity On Transverse Tensile Strength Of Filament Wound/Cvd Carbon-Carbon Composites., Gilbert William Brassell

Nuclear Engineering ETDs

Filament wound/CVD (Chemical Vapor Deposition) carbon­carbon composites have received considerable attention within the past few years due to desirable characteristics such as high heat of ablation, thermal shock resistance, strength improvement at elevated temperatures, and chemical inertness. However, poor mechanical properties in the trans­verse direction have hampered the total effectiveness of these composites in some applications and a study of the effects of porosity on transverse tensile strength of filament wound/CVD carbon carbon composites has been conducted.

Two types of filament wound/CVD carbon carbon composites were studied. A standard filament wound/CVD carbon composite, and a composite similar to the standard …

Comprehensive Calculations Of The Parameters Describing Proton Energy Loss In Matter, Joseph F. Janni

Nuclear Engineering ETDs

Extensive calculations have been made of the mean energy loss, pathlength, range, multiple scattering, and pathlength straggling of protons in many materials. Emphasis has been placed on obtaining accurate results, especially for heavy materials and protons of very low energy. Values of the energy loss between .01 and 1.0 Mev were obtained by smoothing and interpolating experimental information. Above 1.0 Mev, the Bethe equation with all the necessary shell corrections has been used. Values of the adjusted ionization potential have been determined by least squares fitting the Bethe equation to all available energy loss data. The polarization effect has been …

Techniques For Active 3he Activation Analysis For Carbon And Oxygen, William Mort Sanders

Nuclear Engineering ETDs

The surface and body concentrations of carbon and oxygen have been measured in various materials using ³He activation. Channeling techniques have been used to differentiate between interstitial and substitutional location of these impurities.

Thin target excitation functions were determined for (³He,p) reactions with carbon and oxygen over a ³He energy range from 2.5 to 9.0 MeV. These data were used to calculate the activation curves for various combinations of incident particle energy, impurity distributions, and material.

Information on several computer codes used during this study is presented.

Dynamic Measurements Of The GrüNeisen Coefficients Of Tantalum, Uranium, And Uranium-Molybdenum Alloys, James E. Gover

Nuclear Engineering ETDs

Hooke's Law, Newton's Law, and the Grüneisen Equation of State are combined to develop a non-homogeneous, displacement wave equation and the stress/displacement relationship for an isotropic solid in which there has been a time and spatially dependent change in thermal energy. These equations are applied to two solids that are in perfect mechanical contact. One of the materials has had its thermal energy changed along one direction by a high energy electron beam while the thermal energy of the other has remained unchanged. It was assumed that the time dependence of the thermal energy change could be approximated by a …

Numerical Simulation Of Partially Neutralized Relativistic Electron Streams., Ludwig Adam Gritzo

Nuclear Engineering ETDs

The self-focusing of partially neutralized relativistic electron streams {Bennett pinch) is briefly discussed, and analytic solutions for idealized sets of conditions are reviewed.

A computer code for the numerical simulation of the drifting of a relativistic electron stream through an initially neutral gas, with the concurrent production and motion of ions and secondary electrons, is discussed in detail. The simulation conditions are restricted to (1) electron streams whose transverse momentum is small compared with their longitudinal momentum, and (2) low gas pressures, where the background plasma current and current density are low compared with the injected current. Only those electromagnetic …

Transport Calculations In Particle-Loaded Media, Gary J. Scrivner

Nuclear Engineering ETDs

Particle-loaded materials are sometimes used for radiation shielding. In many cases shielding calculations, performed with the assumption of a homogeneous medium having the appropriate ratio of particle-to-matrix material, are grossly inadequate. The exact distribution of particles within such materials is probabilistic in nature, and, therefore quantities, such as the transmitted flux, become random variables. To reasonably evaluate the effectiveness of this type shielding, one must obtain the expected values and corresponding standard deviations of those quantities of interest.

In this dissertation, two models of a particle-loaded shield are investigated. The first is an artificial material postulated to consist of constant-thickness …

Prompt Neutron Decay Constants In A Reflected Fast Burst Reactor, Charles Clayton Price

Nuclear Engineering ETDs

A mathematical model describing the kinetic response of a reflected fast burst reactor is developed using point reac­tor theory. The equations of the model are used to derive a reflected inhour relationship and a two region Rossi-alpha equation.

The model is investigated for three reactor-reflector configurations; the bare reactor, the reactor with a radially symmetric steel reflector, and a reactor with a radially sym­metric polyethylene reflector. This investigation includes the results of a calculational study using Monte-Carlo tech­niques and an experimental program using Rossi-alpha, pulsed neutron, and reactor burst techniques on the Sandia Pulsed Reactor SPR II.

A Type I …

The Time-Dependent Transport Of Monoenergetic Neutron In Plane Geometry With Delayed Neutron Production, Nelson S. Demuth Jr.

Nuclear Engineering ETDs

The initial-value problem for the transport of monoenergetic neutrons in slab geometry with delayed neutron production is studied using numerical methods based on the analysis of Kaper. The eigenvalues and eigenfunctions of the transport operator are found by numerical solution of the equations which result from application of the normal mode expansion method. The residual terms in this form of the solution of the initial-value problem are evaluated by direct numerical integrations on the (complex) resolvent set of the transport operator. The results obtained in this study are compared with the results from the method of matched asymptotic expansions.

Mass Transfer Of Oxygen In Sodium Cold Traps, Charles Clellan Mcpheeters

Nuclear Engineering ETDs

Cold traps have been used extensively for controlling oxygen concentration in sodium systems. Cold traps utilize the positive temperature dependence of the solubility of sodium monoxide in sodium and the resultant precipitation of sodium monoxide at low sodium temperatures. Sodium monoxide precipitation is here assumed to be heterogeneous because of the strong effect of surface area on the precipitation rate shown in previous packless cold trap experiments. Growth of crystals from a super-saturated solution is said to proceed according to the equation

where dm/dt is the rate of mass accumulation on the crystal, k is an over-all mass transfer coefficient …

Generalized Transport Equations For Partially And Fully Ionized Nonequilibrium Gases., Dermod Kelleher

Nuclear Engineering ETDs

Transport equations are developed for the number densities, mean velocities, temperatures, stresses and heat fluxes of the constituents of an ionized gas by taking velocity moments of the Boltzmann equation. These equations are closed out by utilizing the Grad 13-moment approximation for each distribution function. This approximation provides a representation for the distribution function of each constituent which has as its first term a Maxwellian about the constituent mean velocity, and remaining terms which describe the deviation of the distribution function from this local constituent Maxwellian and which have as their coefficients the constituent traceless stress tensor and the constituent …

Effect Of Sample Geometry On Decay Constant Measurements In Water Using The Pulsed Neutron Technique, Debow Freed

Nuclear Engineering ETDs

The pulsed neutron technique has been employed at a steadily increasing rate since significant results from its use were first reported in 1954. This technique has permitted direct measurement of several parameters important in the nuclear field which previously had to be measured by indirect means.

An Analysis Of Neutron Resonance Detectors In Critical Uranyl-Fluoride Heavy Water Systems., William H. Roach

Nuclear Engineering ETDs

The measurement of neutron flux spectra in reactors is a problem which can be approached in several ways, depending on the information desired. For high energy measurements, threshold detectors are often used; if spatial information of the flux is required, some type of fission detector may be employed. For flux magnitude measurements in the epithermal energy range, foils of elements which have strong neutron absorption resonances are commonly utilized. If the resonance is sufficiently isolated from other resonances and the contribution from the resonance to the total resonance absorption integral of the element is large, then it is a fairly …

A Transient Thermal Analog Of Nuclear Reactors, James R. Hume

Nuclear Engineering ETDs

The nuclear reactor is presently receiving considerable attention as a possible source of energy for stationary power plants and propulsion systems. This has stimulated interest in many engineering problems which become very significant in reactor design work. The response of the reactor core heat transfer system to changes in power generation is one of these problems.