Nuclear Engineering Commons^™

System And Method For Quantitative Imaging Of Chemical Composition To Decompose More Than Two Materials, Xin Liu, L. Yu, C. H. Mccollough

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A system and method for decomposing more than two materials in an imaging object includes performing a CT imaging acquisition of a portion of an imaging object using at least two energy levels to acquire imaging data associated with each of the at least two energy levels. A total mass attenuation of the imaging data is expressed as a weighted sum of constituent element mass attenuation coefficients and an effective atomic number and density of the constituent elements in the portion of the imaging object is determined by one of a number of methods. Accordingly, concentration of the constituent elements …

System And Method For Quantitative Imaging Of Chemical Composition To Decompose Multiple Materials, Xin Liu, L. Yu, C. H. Mccollough

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The present invention provides a material decomposition method capable of determining the distribution of density and constituent material concentration throughout an imaged object. The concentration, in the form of a mass fraction, mass percent, weight fraction, or weight percent, is determined from CT images acquired at different energy levels. The ratio of attenuation coefficients associated with one energy level to attenuation coefficients associated with another energy level is determined and used as an index in a lookup table to determine the concentration of a given material throughout the imaged object.

Preliminary Evidence Of Field Induced Rhenium Etching By Xef₂ At High Vacuum, M. Aghazarian, D. N. Ruzic, Carlos Henry Castano Giraldo

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Preliminary evidence of enhanced etching of rhenium by XeF2 under the influence of an electric field (3.36 GV/m) is presented. Scanning electron microscope photographs of sharp rhenium tips show etching of at least 0.40 µm ±0.07 in 32 min at the point of maximum electric field, indicating a field enhanced etching rate of 13 nm/min ±2. A control experiment shows a maximum spontaneous etching of rhenium by XeF2 of 0.1 µm ±0.07 in 30 min, indicating a maximum possible spontaneous etching rate of rhenium by XeF2 of 3 nm/min ±2. The spontaneous rate of tungsten by XeF2 reported in the …

Reactivity Control Schemes For Fast Spectrum Space Nuclear Reactors, Aaron E. Craft, Jeffrey C. King

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Several different reactivity control schemes are considered for future space nuclear reactor power systems. Each of these control schemes uses a combination of boron carbide absorbers and/or beryllium oxide reflectors to achieve sufficient reactivity swing to keep the reactor subcritical during launch and to provide sufficient excess reactivity to operate the reactor over its expected 7-15 year lifetime. The size and shape of the control system directly impacts the size and mass of the space reactor's reflector and shadow shield, leading to a tradeoff between reactivity swing and total system mass. This paper presents a trade study of drum, shutter, …

Phantom For Evaluating Accuracy Of Image Registration Software, B. Y. Choe, H. S. Jin, R. H. Juh, Hyoung-Koo Lee, J. Y. Song, T. S. Suh

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Provided is a phantom for evaluating the accuracy of image registration software based on a result of matching tomograms of a predetermined position of the phantom, taken using two or more imaging apparatuses. Accordingly, it is possible to more efficiently evaluate the accuracy of the image registration software by comparing the tomograms with one another using a three-dimensional analysis. In addition, it is possible to facilitate the comparison of the tomograms with one another by installing a plurality of indicating bars in the phantom so that their cross sections can appear on each of the tomograms.

Reduced Shell Model Calculations Of 111Sb And 112Sb, E. Dikmen, T. Akyürek

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The low-lying states of the mid-heavy odd-even 111Sb and odd-odd 112Sb isotopes are calculated for the first time within the shell model framework. The shell model calculations have been carried out within the reduced model space including the single particle orbits 1d5/2, 0g7/2, 1d3/2, 2s1/2. We obtain the energy spectra for the 111Sb and 112Sb isotopes in the reduced model space by using CD-Bonn two-body effective nucleon-nucleon interaction. The energy spectra are compared to the experimental results to give some discussion about the low-lying states of 111Sb and 112Sb. © 2007 Chinese Physical Society and IOP Publishing Ltd.

Equivalent Circuit For Transient Conduction And Convection Systems, Bassam Sabry Mohammad Abdelnabi

Masters Theses

"Transient response of a natural convection system is investigated by numerical simulation using FLUENT code. An Integrator Circuit analogy was recently proposed for natural convection system. The proposed analogy was further confirmed by these recent simulations. New simulation results also suggest that a natural convection system acts as a "Low Pass" filter for transients. Transient transmission/attenuation factor was found to be a function of both fluid properties and the flow characteristics. Transmission/attenuation factor was also found to be a strong function of fluctuation frequency"--Abstract, page iv.

2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla

Undergraduate Research Conference at Missouri S&T

No abstract provided.

Nanometal Containing Nanocomposites And Photolithographic Polyaniline Nanofibers, Frank D. Blum, Sunil K. Pillalamarri, Lalani K. Werake, J. Greg Story, Massimo F. Bertino, Akira Tokuhiro

Chemistry Faculty Research & Creative Works

A report on recent progress from our laboratories on the nanostructures produced from novel synthesis techniques will be discussed. Using high-energy radiation (γ-rays) we have been able to produce conducting polymer nanofibers and nanorods of polyaniline and polypyrrole without the use of a separate template or capping agent. This technique has been extended, with the addition of metal ions, to a "one pot" synthesis, producing conducting nanocomposites. These nanocomposites contain metal nanoparticles which decorate the conducting nanofibers. We have also recently shown that these systems can be photopatterned to produce novel structures. We believe that these systems will be useful …

Gamma-Ray Induced Photoconductivity In Pyrex, Quartz, And Vycor, Shoaib Usman, Lubna Shoaib, James N. Anno

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Results of an experimental investigation are reported on photoconductive response of Pyrex, Quartz and Vycor. This research was conducted as a feasibility study for developing a new gamma dose measurement device based on the principle of photoconductivity. However, data collected in this study are equally valuable for various other applications where these materials are to be used in high radiation field. Our experiments and analyzes indicated that the selected dosimeter materials exhibit photoconductivity and respond to changes in gamma dose rate within a useful range. Pyrex glass suffered radiation damage at a relatively high dose rate of 0.25 Gys/sup -1/. …

Bimetallic Pt-Ag And Pd-Ag Nanoparticles, Frank D. Blum, Akira Tokuhiro, Massimo F. Bertino, Carmen M. Doudna

Chemistry Faculty Research & Creative Works

We report studies of bimetallic nanoparticles with 15%-16% atomic crystal parameters size mismatch. The degree of alloying was probed in a 2-nm Pt core (smallest attainable core size) of Pt-Ag nanoparticles (completely immiscible in bulk) and 20-nm-diameter Pd-Ag nanowires (completely miscible in bulk). Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical (nanowire) morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small …

Niel Calculations For High-Energy Heavy Ions, John W. Wilson, I. Jun, M. A. Xapsos, E. A. Burke, F. F. Badavi, L. W. Townsend

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Calculations of NIEL are reported for heavy ions prominent in the space environment for energies ranging from 200 MeV per nucleon to 2 GeV per nucleon.

An Integral Form Of The Variational Nodal Method, M. A. Smith, G. Palmiotti, E. E. Lewis, Nicholas Tsoulfanidis

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

An integral form of the variational nodal method is formulated, implemented, and tested. the method combines an integral transport treatment of the even-parity flux within the spatial node with an odd-parity spherical harmonics expansion of the Lagrange multipliers at the node interfaces. the response matrices that result from this formulation are compatible with those in the VARIANT code at Argonne National Laboratory. Spatial discretization within each node allows for accurate treatment of homogeneous or heterogeneous node geometries. the integral method is implemented in Cartesian x-y geometry and applied to three benchmark problems. the method's accuracy is compared to that of …

Laser Writing Of Semiconductor Nanoparticles And Quantum Dots, Massimo F. Bertino, Raghuveer Reddy Gadipalli, J. Greg Story, C. G. Williams, Guo-Hui Zhang, Chariklia Sotiriou-Leventis, Akira Tokuhiro, Suchi Guha, Nicholas Leventis

Physics Faculty Research & Creative Works

Silica aerogels were patterned with CdS using a photolithographic technique based on local heating with infrared (IR) light. The solvent of silica hydrogels was exchanged with an aqueous solution of the precursors CdNO₃ and NH₄ OH, all precooled to a temperature of 5°C. Half of the bathing solution was then replaced by a thiourea solution. After thiourea diffused into the hydrogels, the samples were exposed to a focused IR beam from a continuous wave, Nd-YAG laser. The precursors reacted in the spots heated by the IR beam to form CdS nanoparticles. We lithographed features with a diameter of …

A Finite Subelement Generalization Of The Variational Nodal Method, M. A. Smith, Nicholas Tsoulfanidis, E. E. Lewis, G. Palmiotti, T. A. Taiwo

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The variational nodal method is generalized by dividing each spatial node into a number of triangular finite elements designated as subelements. the finite subelement trial functions allow for explicit geometry representations within each node, thus eliminating the need for nodal homogenization. the method is implemented within the Argonne National Laboratory code VARIANT and applied to two-dimensional multigroup problems. Eigenvalue and pin-power results are presented for a four-assembly Organization for Economic Cooperation and Development/Nuclear Energy Agency benchmark problem containing enriched UO2 and mixed oxide fuel pins. Our seven-group model combines spherical or simplified spherical harmonic approximations in angle with isoparametric linear …

Radiation Resistance Testing Of Mosfet And Cmos As A Means Of Risk Management, Akira Tokuhiro, Massimo F. Bertino

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Whether for military, research (space, accelerator physics) and/or civilian use, risk avoidance against radiation-induced damage is not possible with COTS parts. Thus the sensible approach is risk management. We recommend a sensible risk management approach as follows: 1) know the radiation environment of the intended application to the extent possible; 2) know the effects of ionizing radiation on the component(s) of interest; 3) know the requirements of the application; 4) identify the candidate or chosen components; 5) test the components; 6) design-in safety factor margins to the extent possible.

Traditional Signal Pattern Recognition Versus Artificial Neural Networks For Nuclear Plant Diagnostics, Shahla Keyvan

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

This paper introduces a new tool based on a traditional noise analysis technique for monitoring reactor components' signal condition. It also presents the performance of artificial neural networks for pattern recognition to the same set of reactor signals and provides a comparison of these two techniques. Reactor pump signals from the Experimental Breeder Reactor (EBR-II) are utilized here. Collected signals such as pump power, pump speed, and pump pressure are obtained from already installed sensors in the reactor. The signals utilized are collected signals as well as generated signals simulating the pump shaft degradation progress. From the study of time …

Nuclear Fuel Pellet Inspection Using Artificial Neural Networks, Shahla Keyvan, Xiaolong Song, Mark Kelly

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Nuclear fuel must be of high quality before being placed into service in a reactor. Fuel vendors currently use manual inspection for quality control of fabricated nuclear fuel pellets. In order to reduce workers' exposure to radiation and increase the inspection accuracy and speed, the feasibility of automation of fuel pellet inspection using artificial neural networks (ANNs) is studied in this paper. Three kinds of neural network architectures are examined for evaluation of the ANN performance in proper classification of good versus bad pellets. Two supervised neural networks, back-propagation and fuzzy ARTMAP, and one unsupervised neural network called ART2-A are …

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 …

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 …

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 …

Calculation Of Neutron Flux And Neutron Radiation Dose In A Human Phantom, L. Alan Smith

Opportunities for Undergraduate Research Experience Program (OURE)

At present, the neutron dose received by personnel working in nuclear installations is recorded by body surface dosimeters worn by workers. To estimate the true neutron dose to internal organs, this ’surface dose” is multiplied by empirical factors to account for the attenuation of the body itself.

The objective of this work was to obtain better estimates of the internal dose by calculating the attenuation of the neutron flux provided by the body. Using DOT, a 2-D radiation transport code, the neutron flux as a function of energy was calculated at several points in a 2-D model of the human …

Solution Of Divertor Magnetohydrodynamic Equilibria For The Study Of Alpha Particle Edge Transport In Fusion Plasmas, J. W. Schumer

Opportunities for Undergraduate Research Experience Program (OURE)

Removal of thermalized alpha particles from deuterium- tritium (D-T) fusion plasmas can be accomplished through the use of divertor magnetic fields if the magnetohydrodynamic (MHD) equilibria is well understood [1]. Modifying a MHD variational energy principle for poloidal flux surfaces described by �� = ��(ρ, θ) results in an inverse Fourier representation of the three-dimensional (3-D) equilibria solution. Application of the �� = ��(ρ, θ) flux profile allows transformation of the magnetic field into a non-singular coordinate system along the divertor separatrix [2] and therefore, analysis of different divertor schemes. Derivation of the coupled, non-linear differential equations follows [5] except …

A Heat Balance Program For A Nuclear Power Plant, Timothy C. Steadham

Opportunities for Undergraduate Research Experience Program (OURE)

In a coal fired power plant, the steam leaving the boiler can reach 1000 °F and 3000 psia; this state is superheated considerably. On the other hand, a nuclear power plant is not capable of reaching such conditions without compromising reactor safety and integrity. Therefore, the steam leaving the reactor might only be a few degrees superheated, and hence the steam leaving each turbine will be wet. Since wet steam will erode turbine blades very quickly, devices must be placed between turbines to separate the steam into saturated vapor and saturated liquid. The steam is routed through the next turbine …

Sensor Signal Analysis By Neural Networks For Surveillance In Nuclear Reactors, Shahla Keyvan

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The application of neural networks as a tool for reactor diagnostics is examined here. Reactor pump signals utilized in a wear-out monitoring system developed for early detection of the degradation of a pump shaft [17] are analyzed as a semi-benchmark test to study the feasibility of neural networks for monitoring and surveillance in nuclear reactors. The Adaptive Resonance Theory (ART 2 and ART 2-A) paradigm of neural networks is applied in this study. The signals are collected signals as well as generated signals simulating the wear progress. The wear-out monitoring system applies noise analysis techniques and is capable of distinguishing …

Control And Data Reduction Software For Umr Neutron Spectrometer, Matthew K. Mclaughlin

Opportunities for Undergraduate Research Experience Program (OURE)

A double-scatter time-of flight neutron spectrometer has been obtained by the Nuclear Engineering department of the University of Missouri-Rolla (UMR). As this device was an experimental prototype which was never brought to full operation, the chance to work with two of the original builders of the spectrometer at EG&G Idaho was an excellent opportunity. Part of the work being done with the detector is the development of a PC-based software package for machine control, data acquisition, and data reduction. It is this part of the project which has been supported by UMR’s Opportunities for Undergraduate Research Experience (OURE) program.

A Computer Simulation Of The Umr Reactor, H. Allen Wilkins

Opportunities for Undergraduate Research Experience Program (OURE)

The Opportunities for Undergraduate Research project entitled, "A Computer Simulation of the UMR Reactor" had two goals. To produce a reactor simulation to be used in creating an artificial intelligence based reactor simulation for the UMR Nuclear Reactor and to produce a means of teaching students the fundamentals of reactor operations.

The primary purpose was to create a program which would simulate all the situations one would encounter in actual reactor operation. With the simulator the artificial intelligence system could be thoroughly tested before use with actual reactor data.

This same simulator would be used as a teaching aid for …

Dose Rate Determination Of The Highly-Enriched Uranium Fuel At The University Of Missouri-Rolla Reactor In Preparation For Transportation, Alice Ann Netzer

Masters Theses

"An analytical model was developed in order to accurately estimate the dose rates in air of the highly-enriched uranium (HEU) fuel at the University of Missouri - Rolla Reactor. Based upon these results, a method is proposed to remove the fuel from the reactor.

First thermoluminescent dosimeters (TLDs) were exposed under water to each of the fuel elements in the reactor pool, except for the four control rodded elements. A model was developed to use the in-water TLD readings to calculate the dose rate of the fuel elements in air at 1 foot and 3 feet. The fuel was modeled …

Mixed Convection In Laminar/Turbulent Separated Backward-Facing Step Flows, Jen-Tai Lin

Doctoral Dissertations

"Mixed convective heat transfer results for two-dimensional laminar/turbulent flow in a duct with a backward-facing step are reported. The two walls forming the duct are maintained at uniform but different temperatures. The straight wall is maintained at the inlet air temperature, while the downstream section of the stepped wall is heated to a higher temperature. This study focuses on a backward-facing step geometry with an expansion ratio of two. The present laminar study examines a wide range of inlet flow and wall temperature conditions to cover the domain from buoyancy-assisting mixed convective flow, pure forced convective flow, buoyancy-opposing mixed convective …