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Development Of Dose Coefficients For Radionuclides Produced In Spallation Targets, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

Dose coefficients permit simple determination of radiation dose associated with various exposure scenarios, and ultimately permit radiation safety personnel to assess the health risks to workers in a nuclear facility. Specifically, radiation safety personnel use dose coefficients to determine the radiation dose incurred to a tissue or organ system from a given exposure. These parameters are often expressed in terms of Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs).

Results from this study will be used to produce ALIs and DACs for these rare radionuclides created by spallation target systems that are not included in Federal Guidance Report …

Development Of A Systems Engineering Model Of The Chemical Separations Process, Yitung Chen, Darrell Pepper, Sean Hsieh

Separations Campaign (TRP)

The chemical processing of used nuclear fuel is an integral component of any strategy for the transmutation of nuclear waste. Due to the large volume of material that must be handled in this first step of the transmutation process, the efficiency of the separations process is a key factor in the potential economic viability of the transmutation strategies. The ability to optimize the chemical separation systems is vital to ensure the feasibility of the transmutation program.

Systems analysis, or total systems modeling, is one of the strongest tools available to researchers for understanding and optimizing complex systems such as chemical …

Nuclear Criticality, Shielding, And Thermal Analyses Of Separations Processes For The Transmutation Fuel Cycle, William Culbreth

Separations Campaign (TRP)

The first step in any transmutation strategy is the separation of radionuclides in used nuclear fuel. The current separation strategy supporting the Advanced Fuel Cycle Initiative (AFCI) program is based on the use of a solvent extraction separation process to separate the actinides, fission products, and uranium from used commercial nuclear fuel, and on the use of pyrochemical separation technologies to process used transmuter fuels. To separate the fission products and transuranic elements from the uranium in used fuel, the national program is developing a new solvent extraction process, the Uranium Extraction Plus, or UREX+, process based on the traditional …

Development, Fabrication And Study Of Fullerene-Containing Carbon Material (Fcc) For Immobilization Of Iodine: Progress Reports 1-1 And 1-2, Michael Savopulo, Boris E. Burakov

Separations Campaign (TRP)

Immobilization of highly radioactive and long-lived isotope of ¹²⁹I, which is a fission product in spent nuclear fuel, requires development of new durable host-materials. Such materials should be characterized with the following principal features:

• High loading capacity to iodine incorporation
• Chemical durability and radiation resistance in order to prevent iodine release over long time (higher than 105 years) storage under conditions of underground repository of radioactive wastes
• Possibility to use iodine-doped material as a target for iodine transmutation.

Iodine is a very volatile chemical element, and even its chemically strong compounds such as AgI and CuI are not stable …

Development, Fabrication And Study Of Fullerene-Containing Carbon Material (Fcc) For Immobilization Of Iodine: Progress Report 1-3, Michael Savopulo, Boris E. Burakov

Separations Campaign (TRP)

During previous reporting periods we studied properties of iodine doped FCC in comparison with activated carbon. An additional goal was to investigate the possibility to convert iodine doped FCC and activated carbon into ceramic-like material avoiding iodine loss. In order to obtain ceramic based on C_xN_y with fullerene structure we decided to carry out gamma irradiation of iodine doped samples in nitrogen atmosphere (0.7 atm. N₂). It was found that iodine doping and irradiation caused principal changes in composition of FCC such as substituting of fullerene C₆₀ and graphite (both formed by benzene-like carbon …

Development, Fabrication And Study Of Fullerene-Containing Carbon Material (Fcc) For Immobilization Of Iodine: Final Report #1, Michael Savopulo, Boris E. Burakov

Separations Campaign (TRP)

Immobilization of highly radioactive and long-lived isotope of ¹²⁹I, which is a fission product in spent nuclear fuel, requires development of new durable host-materials.

Iodine is a very volatile chemical element, and even its chemically strong compounds such as AgI and CuI are not stable under ultraviolet irradiation or oxidizing conditions. Therefore, development of host materials for iodine immobilization is based on unusual approach – the search and testing of new compounds which were not studied before in respect of iodine sorption and strong fixation.

Laboratory of Applied Mineralogy and Radiogeochemistry of the V.G. Khlopin Radium Institute carries out …

Evaluation Of Fluorapatite As A Waste-Form Material, Dennis W. Lindle, Oliver Hemmers

Separations Campaign (TRP)

Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal is for renewal of the UNLV portion of a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF₄, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and …

Development Of Fluorapatite As A Waste Form: Progress Report 1-2, Boris E. Burakov

Separations Campaign (TRP)

In the framework of this stage of research the samples of Sr-fluorapatite synthesized earlier had to be studied using different methods.

These are samples of the following desired compositions:

1) Sr₁₀(PO₄)₆F₂ from precipitated precursor;

2) Sr₁₀(PO₄)₆F₂ from precipitated precursor and adding Sr(NO₃)₂;

3) Sr₈CsNd(PO₄)₆F_2.3;

4) Initial precursor for the synthesis of un-doped Sr-fluorapatite.

Development Of Fluorapatite As A Waste Form: Progress Report 1-3, Boris E. Burakov

Separations Campaign (TRP)

In the framework of this stage of research we had to carry out synthesis and study of fluorapatite doped with fission product elements including Cs, Sr, noble metals and Zr. During previous reporting period different samples of ceramics based on Sr-fluorapatite have been synthesized. Sample of Cs-Nd-doped ceramic has been recognized as the most interesting for detailed examination by SEM and EMPA methods.

Development Of Fluorapatite As A Waste Form: Final Report 1, Boris E. Burakov

Separations Campaign (TRP)

Research on the apatite family of minerals to determine their suitability in the Flouride Extraction (FLEX) Process, which is part of the radioactive waste management stream.

1) KRI has fabricated and tested special high temperature furnace for fluorapatite synthesis. This equipment might be installed into glove box in order to carry out experiments with real actinides and technetium. The same equipment might be fabricated and installed in Actinide laboratory at HRC by KRI technical staff;

2) Samples of undoped polycrystalline apatite, Ca₅(PO₄)₃F, of low porosity were successfully obtained by sintering in air at 1300°C. …

Fundamental Chemistry Of U And Pu In The Tbp-Dodecane-Nitric Acid System: Quaterly Report, Kenneth Czerwinski, Byron Bennett

Separations Campaign (TRP)

The speciation of hexavalent U and tetravalent Pu will be examined in the TBP-dodecane- nitric acid systems. This topic is chosen based on data needs for separation modeling identified by the AFCI. Emphasis will be placed on studying the influence of nitrate and acetohydroxamic acid on U and Pu speciation as well as conditions where a third phase forms in the organic phase. The organic phase will be 30 % TBP in dodecane. Equal volumes of aqueous and organic phase will be used. The speciation of the actinides in the aqueous and organic phase will be determined by a number …

Inside Unlv, Gian Galassi, Jennifer Vaughan, Carol C. Harter, Richard Flaherty, Rebecca Mills

Inside UNLV

No abstract provided.

Millennium Scholarship Program Hispanic Persisters And Hispanic Non -Msp Persisters, Arlie J Stops

UNLV Retrospective Theses & Dissertations

The Hispanic component of the student body at the Community College of Southern Nevada was the primary focus of this study, which spanned a three-year period of time. Statistics regarding the enrollment and academic success of Hispanic students were collected and analyzed. Particular attention was given to the impact of the state of Nevada's recent Millennium Scholarship Program (MSP) on the Hispanic student population. Enrollment and success of Hispanic students were secondarily compared to that of other student ethnic components; The study, which followed two cohorts of students, found that Hispanic students in both cohorts who participated in the MSP …

Comparing Preservice Teachers' Special Education Knowledge And Attitudes Toward The Placement Of Students With Disabilities, Ronald Tamura

UNLV Retrospective Theses & Dissertations

The purposes of this study were: (a) to compare general and special education preservice teachers' attitudes regarding educational placements for students with disabilities, (b) to determine whether these attitudes are disability specific and, (c) to determine whether change in knowledge has an effect on attitude toward placement over the course of a semester while enrolled in introductory classes about students with disabilities. Two groups of respondents comprised of general education and special education preservice teachers participated in this study. A pretest and posttest format was used to gather information. Specifically, data were collected using the Preservice Teacher Service Delivery Survey …

Charge-Diffusion-Filtration Models For Transport Across The Endothelial Barriers And In The Interstitial Space, Bin Chen

UNLV Retrospective Theses & Dissertations

Vascular endothelium is the principal barrier to, and regulator of, material exchange between circulating blood and the body tissues. Both the endothelial surface glycocalyx and the glycosaminoglycans in the tissue carry negative charge. However, none of the previous studies considered these charge effects on water and solute transport across the endothelium and in the tissue. It is important to understand how charge affects the water and solute transport across the endothelial barriers and in the interstitium because it may provide strategies for controlling transport of charged or uncharged macromolecules in drug delivery; In the first part of this dissertation, to …

Secondary English Language Arts Teachers' Perceptions And Implementation Of Change Policy, Denise De Vito

UNLV Retrospective Theses & Dissertations

Research regarding educational reform in the United States has examined change in public schools, including changes in the role of the teacher. Secondary teachers have been studied regarding school leadership, work atmosphere, and resource availability, but research specific to secondary English Language Arts teachers' perceptions of how policy implementation affects them in their day to day practice is lacKing Factors of change and the effects on teachers' attitudes reflect how teachers as participants of change cope with change reform; This qualitative research study sought a descriptive understanding of practicing secondary English Language Arts teachers and their perceptions regarding the scope …

Teacher Exploration Of Instructional Strategies To Promote Algebraic Thinking, Cynthia Ann Hernon

UNLV Retrospective Theses & Dissertations

The research study investigates the influence of teacher participation in a graduate course fostering the development of algebraic thinking for K--8 students on teacher understanding of the nature of algebraic thinking and on the incorporation of the teaching of algebraic thinking, guided by student discourse, into practice. The traditional high school algebra courses, with high failure rates, are not meeting the challenge of teaching algebra to every student. Thus, mathematics educators and researchers have proposed that problems in the teaching and learning of algebra be addressed before the middle school years by integrating the development of algebraic thinking and reasoning …

The School Experience From The Students' Perspective: A Comparative Case Study Analysis, John Goldhardt

UNLV Retrospective Theses & Dissertations

Since the re-authorization of the Elementary and Secondary Education Act of 2001 (also known as No Child Left Behind), public schools are required to be more accountable in relationship to student achievement. With the current attention on accountability that is based mostly upon standardized tests, it becomes compelling to study the school experience from the students' perspective. The purpose of this study is not to analyze traditional data from students, but to instead, examine the perceptions of high school senior students based upon their schooling experience and its implications for school leaders; Invitational education and critical theory provide a theoretical …

Virtual Learning Community: A Student Exit Survey And Qualitative Framework, David C Diramio

UNLV Retrospective Theses & Dissertations

As the mystery and intrigue surrounding technology use in higher education dissipates, the time has come to bring technological initiatives, such as distance education, into the fold with the rest of campus in terms of assessment, accountability, and policy. Although online education shows promise for setting the collegiate learning experience free from the confines of the lecture hall, new challenges are emerging. For example, attrition rates for courses delivered via the Internet are higher than average, typically ten percentage points higher in online courses than in the traditional campus classroom. In an era of declining resources and renewed interest in …

Exploring Relationships Between Configurations Of Laptop Use And Student Off -Task Behavior, Loretta Donovan

UNLV Retrospective Theses & Dissertations

This study had three purposes: to explore configurations of laptop use in the middle school setting; to explore the range of student off-task behavior during laptop-based learning experiences; and to explore the relationships between the configurations of use and student off-task behavior. Through a framework of educational change and guided by methodologies of the Concerns-Based Adoption Model of change, an Innovation Configuration Map was developed and used to collect data for this study. Three unique configurations of use were identified: The Jetsons, in which technology is fully integrated and a natural part of teaching, learning, assessment, and communication; Star Trek …

Assessment Of Bivariate Normality, Pejmon Sadri

UNLV Retrospective Theses & Dissertations

There are three methods, which are most commonly used to assess the bivariate normality of paired data, two of which are also used to assess the multivariate normality. Nevertheless, none of the methods is very efficient or conclusive in their assessment of bivariate normality. In this thesis we are proposing a new method to test bivariate normality. This new method makes use of a set of if and only if conditions inherent in the theory of bivariate normal distribution. The proposed new method is highly efficient, accurate, and very easy to apply using any available standard statistical software.

The Randomized Server Problem, Qin Zhang

UNLV Retrospective Theses & Dissertations

In the k-server problem there are k ≥ 2 identical servers which are located at k points in a metric space M. If there is a request to a point r ∈ M, one of the servers must be moved to the request point in order to "serve" this request. The cost of this service is the distance between the points where the server "resided" before the service and after the service. A k-server algorithm A must decide which server should be moved at each step. The goal of A is to minimize the total service cost. Competitiveness makes sense …

Residual Stress Measurements And Analysis By Destructive And Non-Destructive Techniques, Satish Babu Dronavalli

UNLV Retrospective Theses & Dissertations

This investigation is focused on the evaluation of residual stresses resulting from cold deformation and welding in candidate target structural materials such as martensitic Alloys EP-823 and HT-9, and austenitic Type 304L stainless steel (SS). Measurements of residual stresses were performed by both destructive and nondestructive techniques including ring-core (RC), neutron diffraction (ND) and positron annihilation spectroscopy (PAS). The results obtained by the PAS method indicate that the residual stresses in the cold-worked specimens were significantly enhanced with increased level of cold reduction. Residual stress measurements by the RC method on welded specimens consisting of similar materials revealed tensile stresses …

Energy-Absorbing Sandwich Structures Under Blast Loading, Dong Kwan Lee

UNLV Retrospective Theses & Dissertations

An experimental study at the Army Research Laboratories shows that flat panels with foam or honeycomb faceplates transferred more energy to a structure under blast loading relative to a structure without an energy absorbing faceplate. The objective of this work is to simulate non-uniform response of sandwich panels subject to blast loaDing This involves an investigation into the optimum design of a square-celled sandwich structure for energy absorption. Variables under investigation are the core and face sheet thicknesses of the sandwich structure. Results of a design of experiments study are attained, which evaluate the relative contribution of panel variables to …

Non-Linear Optimized Cash Flow Model, Martin J Mack

UNLV Retrospective Theses & Dissertations

During construction of a lump-sum project, progress payments (cash inflow) are paid periodically to contractors for project performance. Contractors are required to pay the direct costs (cash outflow) during construction. The net difference between the cash inflow and outflow are the required overdraft, which the contractor financed from a bank. In order to increase profit margin, contractors look into alternate ways, such as front-end loading (unbalanced bid) and activities shifting. Usually, front-end loading and activities shifting are done in a linear, independent, and sequential method. This linear front-end loading and activity shifting formulation will likely not produce an ideal optimized …

Fabrication Of Nonlithographic Semiconductor Quantum Wire Infrared Photodetector, Pavan Kumar Singaraju Venkata Sai

UNLV Retrospective Theses & Dissertations

The thesis describes novel semiconductor quantum wire infrared photodetectors in the long- and very long-wavelength regions. The infrared photodetectors are based on intersubband transitions in semiconductor quantum wires and have the potential for higher operational temperature, increased signal-to-noise ratio, reduced dark current, wider spectral range and sensitivity to normal incident radiation. The quantum wire IR detectors were implemented using a nonlithographic nanostructure fabrication technique that is capable of producing large arrays of semiconductor quantum wires of a variety of materials and on different substrates. The operational principles, design procedure as well as the implementation of the quantum wire photodetectors using …

Comparative Analyses Of Residual Stresses In Target Sub-System Materials, Anand Venkatesh

UNLV Retrospective Theses & Dissertations

Recent approaches to residual stress measurements in transmutation target structural materials using destructive and nondestructive techniques have been investigated in this research project. A major emphasis has been placed on the use of the Neutron Diffraction (ND) technique to determine the residual stresses in austenitic and martensitic stainless steels subjected to plastic deformation and welding operations. The resultant data have been compared to those obtained by other techniques including positron annihilation spectroscopy, x-ray diffraction and ring-core methods. Cold-worked (CW), three-point-bent (TPB) and welded specimens of similar and dissimilar materials were tested. ND measurements on CW specimens showed enhanced residual stresses …

Flux Profile Modeling Using Monte Carlo Simulation, Ramprasad Vijayagopal

UNLV Retrospective Theses & Dissertations

Molecular beam Epitaxy (MBE) is a process by which semiconductor films are grown on the substrate by physical vapor deposition of the source material in an ultra high vacuum environment. Spatial variations in flux are a result of the shape of the crucible and the geometry of the growth chamber. In this study a process simulation tool for MBE based on a phenomenological model is proposed and elaborated; Two different models based on physical principles are investigated. Model I includes the primary flux from the liquid surface and a secondary flux re-emitted from the crucible walls for the total flux …

Investigation Of Issues Related To The Revision Of Iso 10819, Erik Wolf

UNLV Retrospective Theses & Dissertations

This study has three main goals. The first is to evaluate a proposed change to the input spectra for the ISO 10819 antivibration glove tests. Secondly, this study investigates the effect of palm adapter geometry on linear transmissibility and mean corrected transmissibility values. Finally, the effect of test subject training is discussed and supporting data is shown; 30 rigid acrylic adapters were designed, fabricated, and tested. All adapters fell into one of four categories. Category 1 adapters passed the acceptability criteria. Category 2 adapters failed in the low frequency (16--40 Hz). Category 3 adapters failed in the high frequencies (1000--1600 …

Cfd Analysis Of Three-Dimensional Thermalhydraulics Flow Effects On Wall Concentration Gradient Profiles For Lbe Loop Fittings, Narain Armbya

UNLV Retrospective Theses & Dissertations

The objective of the thesis is to study the effects of thermalhydraulics flows on the wall concentration gradient profiles in LBE loop fittings. To that end detailed models of the fittings have been constructed to study these effects. These fittings include sudden expansion, sudden contraction, t-joint and elbow. The typical flow rates chosen for these simulations are typical of design criteria chosen for the Loop with Reynolds numbers expected around 200,000 and the usual axial temperature profiles which are being characterized in the DELTA loop at LANL. STAR-CD is the simulation package used to make these predictions, which include detailed …