Nuclear Engineering Commons^™

A Comparison Of Computer Codes For Fast Neutron Dosimetry By The Foil Technique, Jau Wen Chen

Masters Theses

"A comparison of the major codes currently used for fast neutron dosimetry based on the foil technique has been made. These codes are SAND II, SPECTRA and RDMM. The comparison is based upon the deviation of calculated from-measured activities, the input data decks, the obtained information, and the computer time required. Four sets of data were used to be compared upon the above four viewpoints, the conclusion reached is that the SPECTRA computer code is the most satisfactory for the UMR Reactor fast neutron spectrum"--Abstract, page ii.

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 …

Electric Field Strength Dependency Of The Rate Of Radiation Induced Degradation In Silicon Planar Devices, Cyrus Hoshang Irani

Masters Theses

"The investigation of electric field strength dependence of the rate of damage introduction, caused by gamma and neutron irradiations in matched is reported. Groups of devices (with varying biases applied to the emitter-base and collector-base junctions to allow study of the electric field strength dependence) were exposed to ionizing gamma radiation from a Co-60 source. Similar experiments were conducted to study the field strength dependence of the rate of space-charge volume damage introduction, caused by fast neutrons (E> l0keV, fission source). The experimental results indicate that the rate of surface degradation, as reflected by the increase of the normalized surface …

Optumr A Digital Computer Program To Cost Optimize A District Heat Piping Network To Remove Waste Heat From Nuclear Power Reactors, James Richard Hendricks

Masters Theses

"The thermal pollution problem of a nuclear reactor electrical generating facility can be eliminated if an economical, productive use for the waste heat can be found. The computer program presented here is designed to investigate the economic feasibility of utilizing this waste heat to heat buildings. The program optimizes a district heating network using the reactor's rejected heat and performs a comparative analysis with a selected conventional heat rejection system. The results indicate that the system is feasible only if the reactor can be sited relatively close (5 miles) to an urban center. Increasing national concern regarding thermal pollution and …

Higher Space Mode Analysis Of A Large Cylindrical Pulsed H₂O System, Harold David Hollis

Doctoral Dissertations

"By utilizing a geometrically centered pulsed source internal to a large (B²_g) ≈ 0.002) cylindrical H₂O system, the neutron flux was measured as a function of position and time. A least square fit of the data yielded the fundamental and five higher decay constants and amplitudes of the thermal neutron flux. Symmetrical and enhanced neutron densities were obtained as a result of the internal source. Long waiting times were unnecessary and data acquisition was accelerated.

The decay constants were found to be independent of position, pulse width, counting time and rates, method of normalization, or waiting time. …

Study Of Neutron Reflection From A Curved Surface Using The Monte Carlo Method, Marion Jay Rackley

Masters Theses

"The reflection patterns for neutrons impinging on both an infinite parabola and an infinite slab were studied using the Monte Carlo method. In the first case neutrons were sent into an infinite parabola (z =x²/2) moving on the XZ plane parallel to the z axis at 5 points, namely: y = 1.5, x = -1.5; y = 1.5, x = -.75; y = 1. 5, x = 0. 0; y = 15, x =.75; y = 1.5, x = 1.5. The results were that there appeared to be a "focusing" of the scattered neutrons. In the second case, neutrons were …

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.

Solution Of The Two-Dimensional Multigroup Neutron Diffusion Equation By A Synthesis Method, William Ray Heldenbrand

Masters Theses

"A method, called the higher mode synthesis method, for the solution of the two-dimensional neutron diffusion equation is developed. In this method, the two-dimensional eigenfunction is expanded in terms of one-dimensional fundamental and higher eigenfunctions. A substitute, weight, and integration procedure is applied and the two-dimensional equation is reduced to a one-dimensional equation in terms of expansion coefficients. The expansion coefficients are combined with the trial functions in order to obtain the two-dimensional eigenfunction. This procedure results in a significant reduction of computation time as compared with standard iteration methods"--Abstract, page ii.

Nuclear Parameter Study In One, Two, And Three Dimensions, Jan Robert Lojek

Masters Theses

"A parameter study comparing one-, two-, and three-dimensional reactor design analyses was undertaken. Computer programs (codes) were used extensively for the computations and running times on the IBM 360/50 were observed. The values of primary concern were neutron flux shapes, effective multiplication factors, and fuel depletion. Dresden I nuclear power plant with fuel type 1 represents the model reactor. Cross section calculations were performed using the nuclear codes HRG and TEMPEST II, FEVER, EXTERMINATOR-2, AND FLARE generated the nuclear parameters"--Abstract, page ii.

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 …

Zap - A Computer Program To Predict Fission Product Concentrations As A Function Of Neutron Flux, Irradiation And Cooling Times, Bruce Earl Koopmann

Masters Theses

"The development of a computer code was undertaken to calculate the fission product nuclide concentration for spent fuel discharged from a nuclear reactor, as a function of irradiation time, cooling time, neutron flux, and element cross section. The necessary input data was prepared from the basic nuclear data for fission of uranium-235 and plutonium-239. Calculations are also made for total or selective element beta heating and total gamma flux according to user selected input groups. These calculations would be useful in fuel element shielding, cooling, shipping and processing studies"--Abstract, page ii.

Fast Neutron Induced Resistivity Changes In Order-Disorder Fe₃Al, Bruce A. Betts

Masters Theses

"Resistivity measurements were made of ordered, disordered and intermediate states of order-disordered specimens of Fe₃Al while being irradiated by neutrons. All the specimens were irradiated at ambient temperature, approximately 35°C in a modified Bulk Shielding Swimming Pool type reactor. The ordered and near ordered specimens increased in resistivity indicating disordering whereas the disordered and near disordered specimens decreased in resistivity indicating an ordering process was occuring [sic]. By extrapolation, an equilibrium condition was determined and estimated at 130-135 micro-ohms-cm resistivity that would remain constant during irradiation because the ordering and disordering affects of neutron irradiation would be in equilibrium"--Abstract, page …

The Design Of A Molten Fueled, Vortex Reactor, For Use As A Rocket Propulsion Device, Robert Philip Schmitt

Masters Theses

"The purpose of this investigation is to design a nuclear reactor which can be used as a rocket propulsion device. The reactor investigated is fueled with a molten uranium-bismuth alloy and utilizes a two phase vortex flow principle. Hydrogen is employed as a coolant and rocket propellant. The hydrogen is heated directly by the fuel thus eliminating the need for heat exchangers. The major part of the investigation consists of a two group neutron diffusion study to show the operational feasibility of this type of reactor and to obtain an optimum design. the study shows that this type of reactor …

Semiempirical Determination Of The Differential Fast Flux Spectrum For U-235 Fission With Water Moderator, Henry Anthony Till

Masters Theses

"The differential fast flux spectrum of the UMR Pool Research and Training Reactor core was determined by simultaneous activations of threshold foil detectors by neutron-nucleon reactions. This represents one phase of the composite neutron environment at two sample irradiation locations and the center of a fuel element during a power operation of 200 Kw (th). To accomplish this measurement a semiempirical least-squares approximation fitting activation date to a theoretical Cranberg U-wet fission spectrum was applied. This is a technique designed specifically for water moderated systems and takes into consideration both virgin and down-scatter neutrons. Gamma decay photopeaks were reduced using …

Investigation By Neutron Diffraction Utilizing White Neutron Radiation, Arlen Ray Schade

Doctoral Dissertations

"The most probable reactor core neutron velocity was determined by analysis of data obtained from single crystals of copper and lithium fluoride. Derivation of the relationship between the maximum in experimental count rate and the most probable velocity, an error analysis of the method, and the computer routine are given for the method used to obtain the most probable velocity. The most probable velocity was used to index the maxwellian distributions from polycrystalline materials. Investigations were done with white neutron radiation of various silicon steel samples of different preferred orientation. A method is described by which the preferred orientation of …

The Decomposition Of 5-Hydroxymethyl-2-Furaldehyde Under Gamma Irradiation, William George Bowles

Masters Theses

"An investigation into the effects of gamma irradiation decomposition of 5-hydroxymethyl-2-furaldehyde (HMF) revealed HMF to be resistant to radiation catalyzed decomposition. A 1.0 normal solution of HMF was irradiated at a dose rate of 4.1 x 10⁵ Rads/hr to a total dose of 8.2 x 10⁶ Rads from a 5000 Curie ⁶⁰Co source. a total of 31 per cent of the HMF decomposed in a zero order reaction, although it was found the HMF decomposed completely under cadmium shielded irradiation in a nuclear reactor with some neutrons present. The reaction rate constant was found to be 4.8 x 10⁻³ moles …

Design And Construction Of A Liquid Nitrogen Cryostat For Use In A Swimming Pool Type Reactor, Bruce B. Joiner

Masters Theses

"The continued expansion of the nuclear reactor facility and the nuclear engineering program dictates the need that a liquid nitrogen cooled cryostat be available at the reactor. This unit would be available for use in graduate and undergraduate laboratories and for graduate research. A liquid nitrogen cooled cryostat capable of maintaining a sample between 77°K to 80°K for an extended period of time in or adjacent to the core of the reactor was designed, constructed, and successfully operated. Recommendations were made for possible modifications to expand the versatility of the system"--Abstract, page ii.

Computer Simulation Of Radiation Damage In Fe₃Al, Roland Otto Jackson

Masters Theses

"A computer program, designed to simulate the ordered state of the B.C.C. alloy, Fe₃Al, was used to study the effects of irradiation on an order-disorder alloy. Twenty-six runs were made with this program representing a variety of initial conditions. In all cases, the final damaged state consisted of Frenkel defects, vacancy-interstitial pairs; and the distance separating these pairs was a sensitive function of the energy and direction imparted to the primary knock-on. Both the vacancy and the interstitial were found to be normal, stable defects, with the interstitial residing in a "split"-configuration oriented in the [110] direction. The threshold energies …

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 …

Shutdown Reactivity Worth Of Reactor Control Rods By A Subcritical Multiplication Method, Leslie Roger Conner

Masters Theses

"Two modified subcritical multiplication methods for measuring the reactivity worth of control elements were developed and investigated. The first involved the calibration of a subcritical count interval by the asymptotic period method. The second involved the calibration of a subcritical count interval by a rod interchange with the reactor regulating rod which had previously been calibrated by the asymptotic period method. The accuracy of these methods is relatively poor. this inaccuracy is due to shadowing effects and to the spatial harmonics which exist in the core. An investigation of the spatial harmonics to determine the best location for the neutron …

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.

Fast Flux Measurement By A Single Multi-Threshold Foil, Kenneth Lawrence Cage

Masters Theses

"The purpose of this investigation is to determine the fast neutron spectrum by use of a single multi-threshold foil. The foils and the elements which constituted the foils were selected by the following criteria: availability of adequate cross-section data, energy dependence of the given reaction, gamma radiation emitted during decay and the half-life of the daughter. The two foils selected were an In-Fe- P pellet, and ALCOA 2509 (Al-Ni). The gamma spectrum of each constitute was stripped from the composite spectra using a least-squares fit. The activation results were utilized to calculate the fast flux using the weighted orthonormal method. …

The Construction Of A Fermi Neutron Chopper For Cross Section Measurements, Cleon Marion Mobley

Masters Theses

"A Fermi neutron chopper and control system has been constructed and put into operation at the end of the UMR Reactor thermal column.

The operation of the chopper has been demonstrated by reproducing the slow neutron cross section data for aluminum and by measuring the previously undetermined slow cross section of cobalt.

The chopper which is powered by a series DC motor consists of 34 cadmium plated stainless steel blades separated by 1/16 inch aluminum spacers. The design incorporates the better characteristics of the Brookhaven and Argonne slow choppers. Speed regulation is accomplished using a silicon controlled rectifier feed back …

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 Study Of The Supercooling Behavior Of High Purity Liquid Bismuth, B. L. Bramfitt

Doctoral Dissertations

"This investigation involves a study of the supercooling behavior of pure bismuth as affected by the melting atmosphere, the amount of superheat, and the intentional addition of metallic and non-metallic foreign materials to the melt. It was found that the amount of oxide on the melt surface is a controlling factor in the degree of supercooling obtainable in bismuth. In the presence of a thick bismuth oxide surface layer the amount of superheat below a 15°C drastically decreases the amount of supercooling due to the retention of nuclei in the surface film that promote nucleation upon cooling of the melt. …

Catalytic Effects On Radiation-Induced Polymerization Of Methyl Methacryalate, David E. Bartine

Masters Theses

"A study has been made of the effect of Kaolin clay particle size and acidity on the degree of radiation-induced polymerization of methyl methacrylate. The results indicate that the degree of polymerization varies with the clay particle size, and that the amount of polymer produced is influenced by the pH of the clay"--Abstract, page ii.

The Construction Of A Single Crystal Neutron Diffraction Unit And Measurement Of Effective Neutron Temperature, Larry Dean Thompson

Masters Theses

"The continued expansion of the nuclear reactor facility and the nuclear engineering program makes it desirable that a neutron spectrometer be available at the reactor facility. This unit would be available for use in graduate and undergraduate laboratories and for graduate research.

A single crystal, white radiation spectrometer including collimator, automatic controls, and shielding was designed and constructed.

The performance of the unit was checked using LiF and Cu crystals. A rocking crystal curve and a θ - 2θ curve was obtained with each crystal. The effective neutron temperature was then determined from the LiF crystal θ - 2θ curve"--Abstract, …

An Evaluation Of The Feasibility Of Neutron Microradiography, Maynard L. Arment

Masters Theses

"The metal working industry has used metallography and microradiography extensively in the past decade. X-ray or gamma microradiography has several advantages as compared to metallography, but a disadvantage concerning alloys of adjacent elements; microradiography cannot distinguish between elements 2 or less atomic numbers apart. Attempts were made using neutron microradiography to distinguish between cadmium and tin rich grains. A maximum resolution of 0.017 inches was found with a calculated possibility of a resolution less than 0.002 inches"--Abstract, page ii.

Impulsive Loading Of Metals And Alloys, William Barnes Mclane

Masters Theses

“This thesis deals with the construction of an explosive deformation apparatus. Using the apparatus an investigation was made of the deformation changes in the structure of a 10% uranium-aluminum alloy and a hot rolled high carbon Manganese steel. Also a study of deformation through different thickness of Stainless Steel, Type-304, plates was carried out.

All of the deformations were obtained using a constant explosive charge consisting of a #6 commercial blasting cap coupled with a commercial chemical booster"--Abstract, page ii.