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Full-Text Articles in Nuclear Engineering

Methods Of Use And Manufacture Of Silver-Doped, Nano-Porous Hydroxyapatite, Cheol-Woon Kim, Richard K. Brow Jul 2019

Methods Of Use And Manufacture Of Silver-Doped, Nano-Porous Hydroxyapatite, Cheol-Woon Kim, Richard K. Brow

Mining and Nuclear Engineering Faculty Research & Creative Works

A silver-doped, nano-porous hydroxyapatite material is provided that can be utilized to capture radioactive iodine, 129I. Methods of using the silver-doped, nano-porous hydroxyapatite material to remove radioactive iodine, and methods of manufacturing the material are also provided.


The Blue Emission At 2.8 Ev In Strontium Titanate: Evidence For A Radiative Transition Of Self-Trapped Excitons From Unbound States, Miguel L. Crespillo, Joseph T. Graham, Fernando Agullo-Lopez, Y. Zhang, William J. Weber Jul 2019

The Blue Emission At 2.8 Ev In Strontium Titanate: Evidence For A Radiative Transition Of Self-Trapped Excitons From Unbound States, Miguel L. Crespillo, Joseph T. Graham, Fernando Agullo-Lopez, Y. Zhang, William J. Weber

Mining and Nuclear Engineering Faculty Research & Creative Works

The origin of the blue emission in SrTiO3 has been investigated as a function of irradiation fluence, electronic excitation density, and temperature using a range of ion energies and masses. The emission clearly does not show correlation with the concentration of vacancies generated by irradiation but is greatly enhanced under heavy-ion irradiation. The intensity ratio of the 2.8 and 2.5 eV bands is independent of fluence at all temperatures, but it increases with excitation rate. The 2.8 eV emission is proposed to correspond to a transition from conduction band states to the ground state level of ...


Achieving High-Power Configuration In Missouri S&T Reactor (Mstr) For Potential Uprate, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo Jun 2019

Achieving High-Power Configuration In Missouri S&T Reactor (Mstr) For Potential Uprate, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Mining and Nuclear Engineering Faculty Research & Creative Works

Research reactor is a powerful tool because of its wide contribution, almost to each field of science. It’s considered to be an essential element for advancing research, development and improvement in nuclear industry. The main goal of research reactor is to produce neutrons which are beneficially used for a wide range of applications such as industrial, agricultural, medical, etc. Neutron spectrum impact it uses. Commonly, neutrons with low energy level, up to 0.5 eV, called thermal neutrons where neutrons with intermediate energy level, ranging from 0.5 eV to 0.10 MeV, called epithermal "resonance" neutrons and neutron ...


Low-Power Core Reconfiguration For Missouri S&T Reactor (Mstr), Thaqal Alhuzaymi, Ayodeji Babatunde Alajo Jun 2019

Low-Power Core Reconfiguration For Missouri S&T Reactor (Mstr), Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Mining and Nuclear Engineering Faculty Research & Creative Works

The Missouri University of Sciences and Technology Reactor (MSTR) is pool-type research reactor which operates up to 200 kilowatt (kW). MSTR used for training and educating nuclear engineering students at Missouri S&T. A several of nuclear researches and irradiation experiments have been conducted in MSTR for example, neutron activation analysis (NAA), neutron radiography, radiolysis, image processing, etc. MSTR initial criticality took place on December 9, 1961. The first power level that MSTR operates at, was 10 kW. The power level alongside the core configuration was upgraded to the current ones, see Fig. 1. MSTR used light-water for moderation and ...


Calculation And Tabulation Of Efficiencies For Tungsten Foil Positron Moderators, R. Alsulami, M. Albarqi, S. Jaradat, Shoaib Usman, Joseph T. Graham May 2019

Calculation And Tabulation Of Efficiencies For Tungsten Foil Positron Moderators, R. Alsulami, M. Albarqi, S. Jaradat, Shoaib Usman, Joseph T. Graham

Mining and Nuclear Engineering Faculty Research & Creative Works

Monte Carlo radiation transport simulations were used to calculate the positron stopping profiles in tungsten positron moderator foils. Stopping profiles were numerically integrated with efficiency kernels derived from Green's function solutions of the 3D diffusion equation to determine the moderation efficiency in both the backscattering and transmission geometries. Stopping profiles and efficiencies were calculated for positron energies from 10 keV to 10 MeV and incident angles from 0° to 75°. The resulting efficiencies agreed with other calculated and measured values in the literature, especially when similar values of the positron diffusion length and surface emission branching ratio were used ...


Recent Advances On Carrier And Exciton Self-Trapping In Strontium Titanate: Understanding The Luminescence Emissions, Miguel L. Crespillo, Joseph T. Graham, Fernando Agullo-Lopez, Yanwen Zhang, William J. Weber Feb 2019

Recent Advances On Carrier And Exciton Self-Trapping In Strontium Titanate: Understanding The Luminescence Emissions, Miguel L. Crespillo, Joseph T. Graham, Fernando Agullo-Lopez, Yanwen Zhang, William J. Weber

Mining and Nuclear Engineering Faculty Research & Creative Works

An up-to-date review on recent results for self-trapping of free electrons and holes, as well as excitons, in strontium titanate (STO), which gives rise to small polarons and self-trapped excitons (STEs) is presented. Special attention is paid to the role of carrier and exciton self-trapping on the luminescence emissions under a variety of excitation sources with special emphasis on experiments with laser pulses and energetic ion-beams. In spite of the extensive research effort, a definitive identification of such localized states, as well as a suitable understanding of their operative light emission mechanisms, has remained lacking or controversial. However, promising advances ...


Radiation Detector Deadtime And Pile Up: A Review Of The Status Of Science, Shoaib Usman, Amol Patil Oct 2018

Radiation Detector Deadtime And Pile Up: A Review Of The Status Of Science, Shoaib Usman, Amol Patil

Mining and Nuclear Engineering Faculty Research & Creative Works

Since the early forties, researchers from around the world have been studying the phenomenon of deadtime in radiation detectors. Many have attempted to develop models to represent this phenomenon. Two highly idealized models; paralyzable and non-paralyzable are commonly used by most individuals involved in radiation measurements. Most put little thought about the operating conditions and applicability of these ideal models for their experimental conditions. So far, there is no general agreement on the applicability of any given model for a specific detector under specific operating conditions, let alone a universal model for all detectors and all operating conditions. Further the ...


Direct Synthesis Of Radioactive Nanoparticles Involving Neutrons, Carlos Henry Castano Giraldo, Maria Camila Garcia Toro, Brian Michael Mills Aug 2018

Direct Synthesis Of Radioactive Nanoparticles Involving Neutrons, Carlos Henry Castano Giraldo, Maria Camila Garcia Toro, Brian Michael Mills

Mining and Nuclear Engineering Faculty Research & Creative Works

A method to synthesize radioactive nanoparticles includes the production of metallic and multimetallic nanoparticles in a single step by providing an aqueous solution of the metal precursor, and irradiating the aqueous solution thereby producing nanoparticles. The obtained nanoparticles include one or more radioactive isotopes of gold, such as 198Au and 199Au as well as radioisotopes of silver when the obtained nanoparticles are bimetallic. The aqueous solution is irradiated in a radiation field that includes neutrons and gamma rays. The radiation field may be provided by a nuclear reactor. The aqueous solution may include silver, and bimetallic nanoparticles may be produced ...


Viscous Sealing Glass For Solid Oxide Fuel Cells, Cheol-Woon Kim, Richard K. Brow Dec 2016

Viscous Sealing Glass For Solid Oxide Fuel Cells, Cheol-Woon Kim, Richard K. Brow

Mining and Nuclear Engineering Faculty Research & Creative Works

A sealant for forming a seal between at least two solid oxide fuel cell components wherein the sealant comprises a glass material comprising B2O3 as a principal glass former, BaO, and other components and wherein the glass material is substantially alkali-free and contains less than 30% crystalline material.


Viscous Sealing Glass Compositions For Solid Oxide Fuel Cells, Cheol-Woon Kim, Richard K. Brow Dec 2016

Viscous Sealing Glass Compositions For Solid Oxide Fuel Cells, Cheol-Woon Kim, Richard K. Brow

Mining and Nuclear Engineering Faculty Research & Creative Works

A sealant for forming a seal between at least two solid oxide fuel cell components wherein the sealant comprises a glass material comprising B2O3 as a principal glass former, BaO, and other components and wherein the glass material is substantially alkali-free and contains less than 30% crystalline material.


Toward Transparency And Broader Safeguards Conclusion: A Closer Look At The Proposed Saudi’S Civilian Nuclear Power Program, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo Dec 2016

Toward Transparency And Broader Safeguards Conclusion: A Closer Look At The Proposed Saudi’S Civilian Nuclear Power Program, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Mining and Nuclear Engineering Faculty Research & Creative Works

The higher the transparency of any civilian nuclear power program, the higher the chance of attracting and securing the long-term foreign nuclear cooperation. For newcomer states, securing nuclear cooperation is essential for successful deployment and implementation of nuclear power program. Complying with an acceptable types of safeguards commitment/protocols plays a major role in increasing transparency. The determination of transparency primarily relies on the presence of sensitive nuclear isotopes–as defined under IAEA’s safeguards–with a nuclear facility. Kingdom of Saudi Arabia (KSA) is considering the deployment of civilian nuclear power program with a projected nuclear capacity ~18 gigawatt-electric ...


The Impact Of The State-Level Concept On “Newcomers”: A Case Study Of The Kingdom Of Saudi Arabia, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo Jul 2016

The Impact Of The State-Level Concept On “Newcomers”: A Case Study Of The Kingdom Of Saudi Arabia, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Mining and Nuclear Engineering Faculty Research & Creative Works

The International Atomic Energy Agency’s (IAEA) latest reports indicate a growing number of states (newcomers) considering the deployment of nuclear energy programs. In developing nuclear infrastructure, newcomers have to employ the prevailing standards to deploy the nuclear program in a secure, safe, and sustainable manner. State-Level Concept (SLC) refers to a comprehensive approach that uses information about a state’s nuclear facilities and capabilities to implement safeguards within the scope of the state’s safeguards agreement. SLC focuses on strengthening the effectiveness and improving the efficiency of the safeguards system considering the State as whole. SLC has been implemented ...


Integrated Microsphere Whispering Gallery Mode Probe For Highly Sensitive Refractive Index Measurement, Hanzheng Wang, Lei Yuan, Cheol-Woon Kim, Jie Huang, Xinwei Lan, Hai Xiao Jun 2016

Integrated Microsphere Whispering Gallery Mode Probe For Highly Sensitive Refractive Index Measurement, Hanzheng Wang, Lei Yuan, Cheol-Woon Kim, Jie Huang, Xinwei Lan, Hai Xiao

Mining and Nuclear Engineering Faculty Research & Creative Works

We report an integrated whispering gallery mode microresonator-based sensor probe for refractive index sensing. The probe was made by sealing a borosilicate glass microsphere into a thin-wall glass capillary pigtailed with a multimode optical fiber. The intensities of the resonant peaks were found decreasing exponentially (linearly in a log scale) with the increasing refractive index of the medium surrounding the capillary. The sensing capability of the integrated probe was tested using sucrose solutions of different concentrations and the resolution was estimated to be about 2.5 x 10-5 in the index range of 1.3458 to 1.3847. The ...


Method To Fabricate Portable Electron Source Based On Nitrogen Incorporated Ultrananocrystalline Diamond (N-Uncd), Anirudha V. Sumant, Ralu Divan, Chrystian M. Posado, Carlos Henry Castano Giraldo, Edwin J. Grant, Hyoung-Koo Lee Mar 2016

Method To Fabricate Portable Electron Source Based On Nitrogen Incorporated Ultrananocrystalline Diamond (N-Uncd), Anirudha V. Sumant, Ralu Divan, Chrystian M. Posado, Carlos Henry Castano Giraldo, Edwin J. Grant, Hyoung-Koo Lee

Mining and Nuclear Engineering Faculty Research & Creative Works

A source cold cathode field emission array (FEA) source based on ultra-nanocrystalline diamond (UNCD) field emitters. This system was constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation a flat-panel source can be used in tomography, radiography, or tomosynthesis. Furthermore, the unit can be used as a portable electron or X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube “forest” (CNT) cathodes. Furthermore, UNCDs have better mechanical ...


Temperature Measurements During High Flux Ion Beam Irradiations, M. L. Crespillo, Joseph T. Graham, Y. Zhang, W. J. Weber Feb 2016

Temperature Measurements During High Flux Ion Beam Irradiations, M. L. Crespillo, Joseph T. Graham, Y. Zhang, W. J. Weber

Mining and Nuclear Engineering Faculty Research & Creative Works

A systematic study of the ion beam heating effect was performed in a temperature range of -170 to 900 °C using a 10 MeV Au3+ ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 x 1012 cm-2 s-1. Different geometric configurations of beam, sample, thermocouple positioning, and sample holder were compared to understand the heat/charge transport mechanisms responsible for the observed temperature increase. The beam heating exhibited a strong dependence on the background (initial) sample temperature with the largest temperature increases occurring at cryogenic temperatures and decreasing with increasing ...


Convective Cooling In A Pool-Type Research Reactor, Susan Sipaun, Shoaib Usman Jan 2016

Convective Cooling In A Pool-Type Research Reactor, Susan Sipaun, Shoaib Usman

Mining and Nuclear Engineering Faculty Research & Creative Works

A reactor produces heat arising from fission reactions in the nuclear core. In the Missouri University of Science and Technology research reactor (MSTR), this heat is removed by natural convection where the coolant/moderator is demineralised water. Heat energy is transferred from the core into the coolant, and the heated water eventually evaporates from the open pool surface. A secondary cooling system was installed to actively remove excess heat arising from prolonged reactor operations. The nuclear core consists of uranium silicide aluminium dispersion fuel (U3Si2Al) in the form of rectangular plates. Gaps between the plates allow ...


Analysis Of The Developing States In The Mena Region Seeking Civilian Nuclear Energy, With A Primary Focus On The Kingdom Of Saudi Arabia (Ksa) And The United Arab Emirates (Uae), Thaqal Alhuzaymi, Ayodeji Babatunde Alajo Jan 2016

Analysis Of The Developing States In The Mena Region Seeking Civilian Nuclear Energy, With A Primary Focus On The Kingdom Of Saudi Arabia (Ksa) And The United Arab Emirates (Uae), Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Mining and Nuclear Engineering Faculty Research & Creative Works

The comprehensive analysis presented here attempts to ana­lyze “newcomer” states in the Middle East and North Africa (MENA), primarily the Kingdom of Saudi Arabia (KSA) and Unit­ed Arab Emirates (UAE), seeking to implement civilian nuclear energy according to their political and economic situations. By investigating their motivations and funding resources for fu­ture nuclear projects, this analysis provides guidance for these states in terms of their nuclear infrastructure and nonprolifera­tion. The overall approach of this analysis relies on the factors for the success of civilian nuclear energy programs identified in experiential studies conducted since the Atoms for ...


Crystallographic Changes In Lead Zirconate Titanate Due To Neutron Irradiation, Alexandra Henriques, Joseph T. Graham, Sheldon Landsberger, Jon F. Ihlefeld, Geoff L. Brennecka, Donald W. Brown, Jennifer S. Forrester, Jacob L. Jones Nov 2014

Crystallographic Changes In Lead Zirconate Titanate Due To Neutron Irradiation, Alexandra Henriques, Joseph T. Graham, Sheldon Landsberger, Jon F. Ihlefeld, Geoff L. Brennecka, Donald W. Brown, Jennifer S. Forrester, Jacob L. Jones

Mining and Nuclear Engineering Faculty Research & Creative Works

Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr0.5Ti0.5O3 after exposure to a 1 MeV equivalent neutron fluence of 1.7x1015 neutrons/cm2. The results showa measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. The results demonstrate a method by ...


X-Ray Digital Industrial Radiography (Dir) For Local Liquid Velocity (Vll) Measurement In Trickle Bed Reactors (Tbrs): Validation Of The Technique, K. A. M. Salleh, M. F. A. Rahman, Hyoung-Koo Lee, Muthanna H. Al-Dahhan Jun 2014

X-Ray Digital Industrial Radiography (Dir) For Local Liquid Velocity (Vll) Measurement In Trickle Bed Reactors (Tbrs): Validation Of The Technique, K. A. M. Salleh, M. F. A. Rahman, Hyoung-Koo Lee, Muthanna H. Al-Dahhan

Mining and Nuclear Engineering Faculty Research & Creative Works

Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (VLL) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure ...


Neutron Irradiation Effects On Domain Wall Mobility And Reversibility In Lead Zirconate Titanate Thin Films, Joseph T. Graham, Geoff L. Brennecka, Paulo Ferreira, Leo Small, David Duquette, Christopher Apblett, Sheldon Landsberger, Jon F. Ihlefeld Mar 2013

Neutron Irradiation Effects On Domain Wall Mobility And Reversibility In Lead Zirconate Titanate Thin Films, Joseph T. Graham, Geoff L. Brennecka, Paulo Ferreira, Leo Small, David Duquette, Christopher Apblett, Sheldon Landsberger, Jon F. Ihlefeld

Mining and Nuclear Engineering Faculty Research & Creative Works

The effects of neutron-induced damage on the ferroelectric properties of thin film lead zirconate titanate (PZT) were investigated. Two sets of PbZr0.52Ti0.48O3 films of varying initial quality were irradiated in a research nuclear reactor up to a maximum 1 MeV equivalent neutron fluence of (5.16± 0.03) x 1015 cm-2. Changes in domain wall mobility and reversibility were characterized by polarization-electric field measurements, Rayleigh analysis, and analysis of first order reversal curves (FORC). With increasing fluence, extrinsic contributions to the small-signal permittivity diminished. Additionally, redistribution of irreversible hysterons towards higher ...


Method And System For Scatter Correction In X-Ray Imaging, X. Wu, J. Hsieh, P. Sainath, Xin Liu Jan 2013

Method And System For Scatter Correction In X-Ray Imaging, X. Wu, J. Hsieh, P. Sainath, Xin Liu

Mining and Nuclear Engineering Faculty Research & Creative Works

Approaches for deriving scatter information using inverse tracking of scattered X-rays is disclosed. In certain embodiments scattered rays are tracked from respective locations on a detector to a source of the X-ray radiation, as opposed to tracking schemes that proceed from the source to the detector. In one such approach, the inverse tracking is implemented using a density integrated volume that reduces the integration steps performed.


Method And Apparatus For Adaptive Scatter Correction, Xin Liu, J. Hsieh, X. Wu Jan 2013

Method And Apparatus For Adaptive Scatter Correction, Xin Liu, J. Hsieh, X. Wu

Mining and Nuclear Engineering Faculty Research & Creative Works

A CT system includes a rotatable gantry having an opening to receive an object to be scanned, an x-ray source configured to project an x-ray beam toward the object having a primary intensity, a detector configured to detect high frequency electromagnetic energy passing through the object and output imaging data, and a data acquisition system (DAS) connected to the detector and configured to receive the imaging data. The system also includes a computer programmed to obtain image projection data of the object from the DAS, correct the projection data using a scatter function that is based at least on a ...


Virtual Prototype Modeling And Simulation Of Pipe Wagon Articulating System, Y. Li, Samuel Frimpong, W. Y. Liu Jan 2011

Virtual Prototype Modeling And Simulation Of Pipe Wagon Articulating System, Y. Li, Samuel Frimpong, W. Y. Liu

Mining and Nuclear Engineering Faculty Research & Creative Works

Virtual prototype of pipe wagon articulating (PWA) system has been developed and simulated based on the kinematics and dynamics of machinery and Automatic Dynamic Analysis of Mechanical Systems (ADAMS) software. It has been integrated with real-time three dimensional (3-D) system simulations for detailed and responsive interaction with dynamic virtual environments. By using this virtual model, the conceptual design examination and performance analysis of the PWA system have been realized dynamically in virtual laboratory. System dynamic force, displacement and tension of pipe have been measured through verifying this 3- D virtual prototype. By comparing the static tension and dynamic tension of ...


System And Method For Quantitative Imaging Of Chemical Composition To Decompose Multiple Materials, Xin Liu, L. Yu, C. H. Mccollough Jan 2009

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

Mining and Nuclear Engineering 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.


Interaction Between Supersonic Disintegrating Liquid Jets And Their Shock Waves, K.-S. Im, S.-K. Cheong, Xin Liu, J. Wang, M.-C. Lai, M. W. Tate, A. Ercan, M. J. Renzi, D. R. Schuette, S. M. Gruner Jan 2009

Interaction Between Supersonic Disintegrating Liquid Jets And Their Shock Waves, K.-S. Im, S.-K. Cheong, Xin Liu, J. Wang, M.-C. Lai, M. W. Tate, A. Ercan, M. J. Renzi, D. R. Schuette, S. M. Gruner

Mining and Nuclear Engineering Faculty Research & Creative Works

The use of additional spectral filtration for dual-energy (DE) imaging using a dual-source CT (DSCT) system was investigated and its effect on the material-specific DEratio was evaluated for several clinically relevant materials. The x-ray spectra, data acquisition, and reconstruction processes for a DSCT system (Siemens Definition) were simulated using information provided by the system manufacturer, resulting in virtual DE images. The factory-installed filtration for the 80 kV spectrum was left unchanged to avoid any further reductions in tube output, and only the filtration for the high-energy spectrum was modified. Only practical single-element filter materials within the atomic number range of ...


System And Method For Quantitative Imaging Of Chemical Composition To Decompose More Than Two Materials, Xin Liu, L. Yu, C. H. Mccollough Jan 2009

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

Mining and Nuclear Engineering 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 ...


Preliminary Evidence Of Field Induced Rhenium Etching By Xef₂ At High Vacuum, M. Aghazarian, D. N. Ruzic, Carlos Henry Castano Giraldo Feb 2008

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

Mining and Nuclear Engineering 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 ...


Reactivity Control Schemes For Fast Spectrum Space Nuclear Reactors, Aaron E. Craft, Jeffrey C. King Jan 2008

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

Mining and Nuclear Engineering 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 ...


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 Jan 2008

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

Mining and Nuclear Engineering 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.


Gamma-Ray Induced Photoconductivity In Pyrex, Quartz, And Vycor, Shoaib Usman, Lubna Shoaib, James N. Anno Jan 2005

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

Mining and Nuclear Engineering 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 ...