Digital Commons Network^™

Characteristics Of Thick Concrete Neutron Reflection, Richard Gordon Taylor

Doctoral Dissertations

Water is considered as a neutron reflector in nuclear criticality safety evaluations because it is readily available and easily forms a close-fitting shape around fissile material. Concrete is commonly encountered industrial environments and can be a more effective reflector than water. Nuclear criticality safety literature reporting experimental and analytical studies involving concrete as a reflector from the 1950’s to the present was reviewed. Nuclear criticality safety community perspective on concrete reflection has evolved from acknowledgement that concrete is a reflector through recognition that concrete can be a more effective reflector than water to current interest in identifying which constituents are …

Deterministic Neutron Transport And Multiphysics Experimental Safety Analyses At The High Flux Isotope Reactor, Christopher James Hurt

Doctoral Dissertations

The computational ability to accurately predict the conditions in an experiment under irradiation is a valuable tool in the operation of a research reactor whose scientific mission includes isotope production, materials irradiation, and neutron activation analysis. Understanding of different governing physics is required to ascertain satisfactory conditions within the experiment: the neutron transport behavior throughout the reactor and the coupled behavior of heat transfer, structural mechanics and fluid flow. Computational methods and tools were developed for robust numerical analysis of experiment behavior at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR), including fully-coupled thermo-mechanics in three plutonium-238 …

Development, Synthesis, And Analysis Of Surrogate Post-Detonation Nuclear Melt Glass, Andrew Vincent Giminaro

Doctoral Dissertations

With the threats facing the world today, there is an ever-increasing need for training the the fields of radiochemistry and nuclear forensics. Training and research in these fields requires reference materials that accurately represent materials that could potentially be encountered. Unfortunately, many of the historical samples of debris from nuclear weapons tests remains classified. Because of this, there is a need for realistic surrogates. This research focuses on the development of surrogates for the bulk and particulate nuclear melt glass that is expected to be found in an urban setting after a nuclear event.

A mathematical model for the creation …

Beta-Delayed Neutron Data And Models For Scale, Kemper Dyar Talley

Doctoral Dissertations

Recent advancements in experimental and theoretical nuclear physics have yielded new data and models that more accurately describe the decay of fission products compared to historical data currently used for many applications. This work examines the effect of the adopting the Effective Density Model theory for beta-delayed neutron emission probability on calculations of delayed-neutron production and fission product nuclide concentrations after fission bursts as well as the total delayed neutron fraction in comparison with the Keepin 6-group model. We use ORIGEN within the SCALE code package for these calculations. We show quantitative changes to the isotopic concentrations for fallout nuclides …

Algorithms And Methods For Optimizing The Spent Nuclear Fuel Allocation Strategy, Gordon Matthew Petersen

Doctoral Dissertations

Commercial nuclear power plants produce long-lasting nuclear waste, primarily in the form of spent nuclear fuel (SNF) assemblies. Spent fuel pools (SFP) and canisters or casks that sit at an independent spent fuel storage installation (ISFSI) at the reactor site store the fuel assemblies that are removed from operating reactors. The federal government has developed a plan to move the SNF from reactor sites to a Consolidated Interim Storage Facility (CISF) or a geological repository. In order to develop a predictable pick-up schedule and give utilities notice of an impending pickup from a reactor site, the federal government developed a …

Development Of Instrumentation And Control Systems For An Integral Large Scale Pressurized Water Reactor, Matthew Rowland Morrow Lish

Doctoral Dissertations

Small and large scale integral light water reactors are being developed to supply electrical power and to meet the needs of process heat, primarily for water desalination. This dissertation research focuses on the instrumentation and control of a large integral inherently safe light water reactor (designated as I²S-LWR) which is being designed as part of a grant by the U.S. Department of Energy Integrated Research Project (IRP). This 969 MWe integral pressurized water reactor (PWR) incorporates as many passive safety features as possible while maintaining competitive costs with current light water reactors. In support of this work, the …

Proton Therapy Facility Shielding, Hadyn M. Daugherty, Isaac C. Waaldschlager, Daniel S. Elkins, Alyxandria Wszolek, Rachel N. Gaudet

Chancellor’s Honors Program Projects

No abstract provided.

Accelerator Shielding For A Bee Hive Irradiator, Robert F. Turner, Matthew O'Neil, Victoria Martin, Saya Rutherford, Danielle Mcfall, Ali Buhamad

Chancellor’s Honors Program Projects

No abstract provided.

Preliminary Investigation For The Development Of Surrogate Debris From Nuclear Detonations In Marine-Urban Environments, Adam G. Seybert

Masters Theses

No nuclear weapon has ever been detonated in a United States city. However, this also means the nuclear forensic community has no actual debris from which to develop analytical methods for source attribution, making the development of surrogate nuclear debris a vital undertaking. Moreover, the development of marine-urban debris presents an unusual challenge because unlike soil and urban structures, which remain compositionally consistent, the elemental composition of harbor and port waters fluctuates considerably due to natural phenomenon and human activity. Additionally, marine vessel composition and cargo can vary dramatically. While early US nuclear tests were carried out in shallow-water coastal …

A Bayesian Approach To Aerial Localization Of Radioactive Sources, Robert Blake Wilkerson

Masters Theses

Securing nuclear material has become an important area for the safety of the U.S. and other countries. Within nuclear security, there is a potential to use orphaned or stolen radioactive sources to cause harm. As the amount of radioisotopes used by government and commercial businesses increases, the need to secure these sources becomes exponentially more difficult. It is well known that there have been several cases of lost, orphaned or stolen nuclear sources across the globe. There is a need for state-of-the-art radiation search methods to search for these potentially dangerous radioactive sources that could be misplaced. While there are …

Out From Darkness And Into The Light: The Role Of Transparency And Social Media In Government, Frances Nichols Bachstein

Doctoral Dissertations

Government agencies that protect secrecy often have a difficult time connecting to the public. Secretive, or perceived secretive government organizations often fall into the nebulous realm of uncertainty for the information consumer. This results in a great deal of misinformation and disinformation being thought of as correct. Since 2008, the US government is moving toward a more transparent, open, and easily accessed information base through social media. Agencies across the government are adopting types of social media communication. However, bureaus that primarily focus on security and safeguarding secrets struggle with how much disclose, which platforms of social media are the …

A Generalized Method For Fissile Material Characterization Using Short-Lived Fission Product Gamma Spectroscopy, Justin Richard Knowles

Doctoral Dissertations

Characterizing the fissile content of nuclear materials is of particular interest to the safeguards and nuclear forensics communities. Short-lived fission product gamma spectroscopy offers a significant reduction in analysis time and detection limits when compared to traditional non-destructive assay measurements. Through this work, a fully generalizable method that can be applied to variations in fissile compositions and neutron spectra was developed for the modeling and measurement of short-lived fission product gamma-rays. This method uses a 238-group neutron flux that was characterized for two pneumatic tube positions in the High Flux Isotope Reactor using flux monitor irradiations. This flux spectrum was …

Characterizing Local Order And Physical Properties Of Rare Earth Complex Oxides, Thomas Jacob Shamblin

Doctoral Dissertations

With more than 500 compositions, materials possessing the pyrochlore structure have a myriad of technological applications and physical phenomena. Three of the most noteworthy properties are the structure’s ability to resist amorphization making it a possible host matrix for spent nuclear fuel, its exotic magnetic properties arising from geometric frustration, and fast ionic conductivity for solid-oxide fuel cell applications. This work focuses on these three aspects of the pyrochlore’s many potential uses. Structural characterization revealed that pyrochlore-type oxides have a tendency to disorder from a high symmetry cubic structure to a lower symmetry orthorhombic arrangement in response to a variety …

Actinium-225 Production Via Proton Irradiation Of Thorium-232, Justin Reed Griswold

Doctoral Dissertations

High energy proton spallation reactions on natural thorium metal targets have been utilized to produce multi mCi [milliCurie] quantities of Actinium-225. Theoretical cross sections for actinium and thorium isotopes as well as for a select number of the fission products produced in these reactions were generated by the Monte Carlo radiation transport code PHITS to simulate the experimental data obtained from sixteen irradiations of thorium metal targets with 25-210 µA [microampere] proton beams ranging in energies from 77 to 192 MeV. Irradiations were conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing …

Development Of A National Human Reliability Program (Hrp) Model For An Emerging Nuclear Country: Nigerian Case Study, Stephen Olumuyiwa Ariyo Dahunsi

Masters Theses

The current demand for electricity and concern of the climate change in emerging countries has led to the rise in the number of nations adopting nuclear technology options. Besides this, the global rise in terrorism and the existence of credible threats in Nigeria and other emerging countries embarking on nuclear program for peaceful application may pose a critical challenge in implementation of this technology. Furthermore, the dual threat issue of providing electricity, while inadvertently producing weapon and radiological material that could similarly undermine international security must be mitigated. In order to achieve the mitigation target, it is highly important to …

Bayesian Framework For High Confidence Signal Validation For Online Monitoring Systems In Nuclear Power Plants, Anjali Muraleedharan Nair

Masters Theses

Online Monitoring systems may offer an effective alternative to the current intrusive calibration assessment procedure used in the nuclear industry. Apart from optimizing the economic and human resource aspects of the currently utilized technique, OLM increases the opportunities for performance assessment and fault detection for nuclear instrumentation. This can lead to possibly extend or ultimately remove the current time based assessment process. Irrespective of its plausible benefits, OLM sees limited applicability in today’s US fleet. Regulatory constraints that limits the large scale implementation of OLM can be addressed by developing highly sensitive signal validation technique and thereby structurally quantify its …

Control System Requirements For A Nuclear Thermal Propulsion System, Adam Hasse, Michael Smith, Bradley Pershke, Andrew Adams, Stephen GilliAm

Chancellor’s Honors Program Projects

No abstract provided.

The Design Of A Fast Neutron Radiography System For Non-Destructive Analysis Of Thick, Dense Objects, Alicia Lauren Swift

Doctoral Dissertations

This dissertation describes the development of a novel time-of-flight (TOF) fast neutron radiography system, TiGReSSE ("Time Gating to Reject Scatter and Select Energy"), for non-destructive analysis of thick, dense objects, such as a spent nuclear fuel cask. Such objects create large scatter fields that mask interior flaws in an image, and are impenetrable with traditional x-ray or low-energy neutron radiography. By using a fast pulsed, high-energy monoenergetic neutron source with TiGReSSE, TOF methods may be employed to completely reject this problematic scatter. If using TOF methods with a fast pulsed, high-energy polyenergetic neutron source instead, partial scatter rejection is possible, …

Adopting 3d Time-Of-Flight Sensing Technology For Design Information Verification In International Safeguards, Matthew Stephen Duchene

Doctoral Dissertations

International safeguards inspectors periodically perform examinations at sensitive nuclear facilities to verify that the facilities’ designs, layouts, and functions are identical to information declared to the International Atomic Energy Agency (IAEA). Such design information verification (DIV) relies on tools and techniques—such as 3D laser range-finding (3DLR) with light detection and ranging (LIDAR) instruments—that are resource intensive. This research explores 3D Time-of-Flight (TOF) sensors as a possible alternative technology to LIDAR systems for performing spatial change-detection to enhance the DIV process.

This research uses the Microsoft Kinect Version 2 (Kinect v2) camera system, one of several commercial depth-sensing instruments that is …

Development And Application Of 3-D Fuel Performance Modeling To Assess Missing Pellet Surface Influence On Pellet Clad Interaction And Clad Failure, Nathan Allen Capps

Doctoral Dissertations

In the late 1970s PCI related failures caused the implementation of startup ramp restrictions. These ramp restrictions where intended to reduce the stresses caused by pellet cladding contact. These ramp restrictions had a significant impact on Westinghouse fueled PWRs, reducing PCI related failure until 2003. Through investigation into these fuel rod failures lead to the conclusion that missing pellet surfaces (MPS) were the root cause of the failures. MPS are local geometric defects in nuclear fuel pellets that result from pellet mishandling or the manufacturing process. The presence of MPS defects can cause stress concentrations in the clad of sufficient …

Process Attribute Monitoring Approach To Gaseous Centrifuge Enrichment Plant Safeguards, Adam Michael Shephard

Doctoral Dissertations

Unattended and remote monitoring systems for the early detection of gas centrifuge enrichment plant (GCEP) misuse have long been sought by the International Atomic Energy Agency (IAEA) safeguards inspectorate, but have yet to be realized for most GCEPs. The primary misuse of concern is high enriched uranium (HEU) production but additionally include excess low enriched uranium (LEU) production and material diversion.

The current research is a feasibility study that investigates a process monitoring approach combined with passive gamma spectroscopy techniques to monitor GCEPs. In the current research, a simulated reference cascade and monitoring system is used to demonstrate several techniques …

Development Of A Reactor Physics Analysis Procedure For The Plank-Based And Liquid Salt-Cooled Advanced High Temperature Reactor, Cole Andrew Gentry

Doctoral Dissertations

Presented in this dissertation is the investigation and development of an adapted lattice physics-to-core simulator two-step procedure based on the SERPENT 2 and NESTLE neutronics codes for the rapid analysis of the Advanced High Temperature Reactor (AHTR). AHTR specific characteristics, such as its longer neutron diffusion length and double heterogeneity of TRISO fuel particles, were taken into consideration when adapting the traditional Light Water Reactor (LWR) lattice to nodal diffusion procedure to AHTR applications. The coarse energy group structure was re-optimized from the traditional LWR 2-group structure to an alternative 4-group structures to address the AHTR specific flux spectrum and …

Machine Learning And Neutron Sensing In Mobile Nuclear Threat Detection, John Edward Sparger

Doctoral Dissertations

A proof of concept (PoC) neutron/gamma-ray mobile threat detection system was constructed at Oak Ridge National Laboratory. This device, the Dual Detection Localization and Identification (DDLI) system, was designed to detect threat sources at standoff distance using neutron and gamma ray coded aperture imaging. A major research goal of the project was to understand the benefit of neutron sensing in the mobile threat search scenario. To this end, a series of mobile measurements were conducted with the completed DDLI PoC. These measurements indicated that high detection rates would be possible using neutron counting alone in a fully instrumented system. For …

Bayesian-Based Methods For Transitioning Between Prognostic Estimates To Leverage Available Data, Alan Y. Nam

Doctoral Dissertations

The availability of failure data directly impacts the empirical prognostic models that can be built. In turn, these models impact the accuracy and uncertainty of remaining useful life (RUL) estimates of systems and components. While ideally a large amount of data of previous failure modes can be collected, the difficulty in obtaining such data can present a significant hurdle. To alleviate the constraints of limited data, Bayesian-based methods of transitioning between different prognostic models were developed. This updating scheme leverages existing data in order to create a unified estimate.

Two novel methods of transitioning are proposed to augment existing prognostic …

Thermal Characteristics Of Lithium Indium Diselenide And Lithium Indium Gallium Diselenide Neutron Detection Crystals, Dustin Carroll Giltnane

Masters Theses

Tracking special nuclear materials (SNM) has never been more important than in the 21^st century where information is transferred rapidly around the globe. Tracking SNM is important to nuclear power, weapons, medicine, and science. Neutron and gamma ray detection are the primary methods of detecting SNM. Increased movement and availability of SNM have increased the demand for radiation detection systems beyond the capacity of traditional neutron detection technologies (³He) [Helium three]. Many alternative neutron detection materials are being considered, including ⁶LiInSe₂ [Lithium Indium Diselenide grown with lithium enriched in lithium six] and its derivative ^{6 …}

Jet Flow Validation Of Positron Emission Particle Tracking Utilizing High Speed Video, Seth Thomas Langford

Masters Theses

Positron Emission Particle Tracking (PEPT) generates 4D Lagrangian particle trajectories and is used to evaluate flow in granular media and complex geometries where optical interrogation methods are not possible. A Multi-Particle PEPT (Multi-PEPT) approach was developed by the University of Tennessee Thermal Fluids Group capable of finding and tracking many particles simultaneously to extend the utility of the PEPT method. This thesis compares 4,014 trajectories generated using the Multi-PEPT method with 3,055 trajectories generated from High Speed Video (HSV) data. All trajectories are acquired in an acrylic test section with water flow using resin beads. The flow geometry includes a …

Advancement Of Computational Nuclear Fuel And Safeguard Tools, Nathan Shoman

Masters Theses

This thesis work was conducted in two separate but related areas: reactor physics and nuclear fuel safeguards. Reactor physics calculations at the assembly level are important to understand the buildup of fission products and major actinides. These calculations can be used to determine the content of a spent fuel assembly prior to reprocessing or disposal at a much cheaper price. This thesis presents an extension to the SCALE (A Nuclear Systems Modeling & Simulations Suite) by developing a lattice model and cross-section library for the CANada Deuterium Uranium (CANDU) 37 and 28 element assemblies. The previous cross-section library was based …

Using Ultrasonic Flowmeters In Integral Pwr Instrumentation, Jason T. Rizk, Shawn Tyler, Matthew Buttrey, Michael Cooper, Kendall Minor

Chancellor’s Honors Program Projects

No abstract provided.

Magnetron Sputtering And Corrosion Of Ti-Al-C And Cr-Al-C Coatings For Zr-Alloy Nuclear Fuel Cladding, Devin Alan Roberts

Masters Theses

The disaster at the Fukushima Daiichi Nuclear Power Plant in March 2011 bought renewed focus to the issue of corrosion in nuclear fuel cladding applications. This thesis reports on the background behind these issues, the investigation strategy, and the analysis of experiments focused on mitigating oxidation of Zr-alloy fuel cladding. This thesis seeks to develop magnetron sputtered Ti-Al-C and Cr-Al-C coatings for Zr-alloy substrates and characterize the as-deposited and corroded samples.

Ti-Al-C and Cr-Al-C coatings were deposited onto ZIRLO, Si, and Al₂O₃ [Aluminum Oxide] substrates under various sputtering conditions. A combinatorial sputtering method was employed to refine …

Cd Transport In Eutectic Licl-Kcl And Contamination Of Zr Metal And Thermal Dehydration Of Bulk Licl-Kcl, Nicholas Azoy Earle

Masters Theses

Researchers at Idaho National Labs have noted unexpectedly high Cd content in empty cladding hulls after processing in the Mark-IV ER. It has been theorized that Cd metal is transporting from the LCC pool through the eutectic LiCl-KCl salt bath to the anode baskets containing the empty hull where it is retained as a Zr-Cd intermetallic. This study sought to replicate the Cd contamination in a dry Ar glovebox using small-scale analogue of the Mark-IV ER salt-Cd metal system.

Anhydrous eutectic LiCl-KCl was an essential regent in this research and experiments were conducted to investigate the feasibility of dehydrating nominally …