Nuclear Engineering Commons^™

Automated Spectrum Analysis And Radionuclide Identification For Robot-Based Gamma Probes, Kennedy Ochieng Mengoh Alila

UNLV Theses, Dissertations, Professional Papers, and Capstones

Gamma spectroscopy is a technique used for the detection and identification of nuclear materials. Gamma-ray emission by radio nuclides is detected using scintillation detectors or semiconductor detectors such as NaI and CZT. Robot-based gamma probes enable radiation measurements in large areas and hard-to-reach cluttered hazardous environments, which significantly reduces radiation risks to personnel. The robotic probes require automated on-board gamma spectrum analysis and capabilities with platforms (unmanned aerial vehicles and unmanned ground vehicle systems) which use Robot Operating System (ROS). The aim of this thesis was to develop a method of an automated spectral analysis and isotope identification for robot-based …

Non-Destructive Characterization Of Ion Irradiated Yttrium Hydride For Microreactor Applications, Ryan E. Pena

Nuclear Engineering ETDs

As energy demands increase, nuclear reactors, especially microreactors, become a promising energy source. These reactors run at high temperatures (>280°C), requiring moderators that can endure these environments. Yttrium hydride is a possible moderator, but little is known about the material’s phase stability and hydrogen retention under irradiation. Through the use of a gold ion beam, samples with stoichiometries ranging from 1.6 to 2.0 were irradiated and tested. Through Vickers hardness testing, a model was created showing a correlation between hydrogen content and hardness. Raman spectroscopy showed high temperature and irradiated samples have significant hydrogen loss. XRD quantified this hydrogen …

Sequential Low Dose Proton Irradiation And Nanomechanical Testing To Understand Mechanical And Microstructural Property Changes In Alloy 709, Abhishek Kc

Nuclear Engineering ETDs

Alloy 709, a 20Cr25Ni alloy, is an advanced austenitic steel designed for next generation sodium fast reactors. Preliminary studies have shown the potential of Alloy 709 in sodium fast reactors. In this study, Precipitate Treated Alloy 709 specimens are irradiated with 2 MeV H⁺ at 500 °C from 0.0057 dpa to 1.7 dpa. Electron microscopy characterization techniques are used to understand the effects of radiation on mechanical properties as well as microstructure of Alloy 709. The microstructure did not show formation of voids, amorphization of precipitates, or increase in grain size up to 1.7 dpa. Correspondingly nano-indentation and micro-pillar …

Coupled Adjoint-Based Perturbation Theory For Dynamics And Heat Transfer Multiphysics For Nuclear Transients, Alexis Maldonado

Nuclear Engineering ETDs

Nuclear reactor multiphysics modeling and simulation (M&S) enable advanced reactor design by analyzing how systems will react over time to various configurations, scenarios, and perturbations. However, high-fidelity coupled transient M&S for reactor cores are computationally expensive, making robust analyses challenging. This work develops a Coupled Adjoint-based Perturbation Theory for dynAmIcs and heat traNsfer (CAPTAIN) framework to rapidly quantify the impact of uncertainty to overall transient responses by generating sensitivity coefficients for temperature, power, and delayed neutron precursor concentrations using forward and adjoint solutions. This work presents an initial proof of principle, verified with direct perturbations to several inputs. Furthermore, this …

A Risk-Informed Approach To Performing The Pre-Closure Safety Analysis For The Deep Borehole Disposal Of Radioactive Waste, Jennifer Elizabeth Leute

Nuclear Engineering ETDs

Deep borehole disposal is an emerging concept which involves disposing of radioactive

waste in boreholes several kilometers deep then backfilling to minimize radionuclide

transport and distribute weight. Unfortunately, little documentation exists on borehole

safety case development, especially for pre-closure operations. This study aims to close

this gap by proposing a graded approach matrix based on consequence, maturity, and

complexity. Two case studies are used to demonstrate this application: Hanford CsCl

capsules and spent PWR assemblies. Simulations are used to predict potential for dose

exposure, revealing CsCl capsules have a much higher potential for being above the 5

rem public dose …

Analysis Of Heat Transfer And Pressure Drops Associated With Twisted Tube Heat Exchangers, Braden Foderaro

Nuclear Engineering ETDs

Several studies have been done on the effects of twisted tubes in heat exchangers, including the correlations that relate the flow parameters to the heat transfer and pressure drop experienced. These studies are new, with the earliest being performed in 1982. As such, there are many correlations covering only certain flow parameters and geometrical configurations such as the Reynolds number and modified Froude number.

This thesis attempts to cover flow regimes and tube geometries not yet studied and yield correlations. Data are gathered from heat exchangers featuring twisted tubes with water as the working fluid. It is noticed that the …

Pria: Process Risk Identification And Analysis, Raymond Fasano

Nuclear Engineering ETDs

This dissertation proposes and evaluates two approaches, with-in a Process Risk and Analysis (PRIA) framework, that advance data-driven hazard discovery in complex cyber-physical systems. First, a transferability-based clustering method groups subspace-identified segments into operational modes, prioritizing cross-predictive performance over raw feature proximity. Second, a Neural Switching Linear Dynamical System (NeuralSLDS) model anchors learning in identified state-space models with Bayesian residuals, calibrated predictive uncertainty, and context-aware operating mode transitions. Together, these methods generate physics-informed, probabilistic world models that can support model-in-the-loop analysis of hazardous trajectories. The approach is validated on a simulated point-kinetics reactor and a centrifugal chiller dataset, demonstrating coherent …

Advancing Radiation Shielding For Human Space Exploration, Bryan Trejo, Lea Scott, Eduardo Farfan

Symposium of Student Scholars

Beyond the safety of the Earth's magnetic field, out into the treacherous reaches of space, lies a harsh environment of radiation. This study examines radiation shielding strategies for crewed spacecraft operating in various environments, including Mars transit and deep space. Within these environments, ionizing radiation remains a critical challenge to long-duration, crewed space travel. Galactic Cosmic Rays (GCR), high-energy protons and heavy nuclei originating outside our solar system, as well as Solar Particle Events (SPE), highly energetic protons ejected continuously during the 11-year solar cycle, are all analyzed in their unique interactions with spacecraft material and biological tissues. Shielding to …

Thermal Management With Supercritical Carbon Dioxide Under Extreme Applications, Devon Hardy

Doctoral Dissertations and Master's Theses

A unique challenge in thermal system design is minimizing the power required to operate cooling systems while maintaining effective heat removal. Traditional cooling systems utilize single-phase fluids where the heat transfer mechanisms are well understood. To meet a variety of cooling demands, a range of technologies are available, including microchannel forced convection, jet impingement, porous media, nanofluids, pin fin arrays, and film cooling, each offering distinct advantages and limitations. While the performance of single- or two-phase cooling systems are generally predictable, in extreme thermal environments, new cooling solutions are needed to improve overall system efficiency and reliability.

Supercritical fluids, particularly …

Notes For Contributors, Editors Space And Defense

Space and Defense

No abstract provided.

Review Article: International Relations: State Of The Field. Paul R. Viotti’S Kenneth Waltz: An Intellectual Biography (Ny: Columbia University Press, 2023)., Damon Coletta

Space and Defense

In this review essay, Damon Coletta examines Paul R. Viotti’s Kenneth Waltz: An Intellectual Biography (Columbia University Press, 2023), positioning it as both a tribute to and a reexamination of one of International Relations’ most influential theorists. Viotti, a former student of Waltz, reconstructs the intellectual development of structural realism—tracing its philosophical and methodological roots from Man, the State, and War (1959) to Theory of International Politics (1979)—while situating Waltz’s scholarship within the geopolitical and academic transformations of the Cold War era. Coletta highlights Viotti’s skillful balance between biography and disciplinary analysis, showing how Waltz’s systemic approach to international politics …

Review Article: Monetary Power And National Security. A 10th Anniversary Review Of Paul R. Viotti’S The Dollar And National Security: The Monetary Component Of Hard Power (Stanford, Ca: Stanford University Press, 2014), Ricardo Crespo

Space and Defense

In this ten-year retrospective, Ricardo A. Crespo reassesses Paul R. Viotti’s The Dollar and National Security (2014) as a foundational text bridging the fields of monetary policy and national security. Viotti’s central thesis—that military power ultimately depends on a stable and privileged monetary foundation—has only grown more relevant amid today’s weaponization of finance and the geopolitics of sanctions. Crespo highlights Viotti’s argument that sustaining the U.S. dollar’s global dominance requires cooperative security and international consensus, noting how historical parallels—from the sterling gold standard to Bretton Woods—illustrate the fragility of monetary hegemony under fiscal mismanagement or political fragmentation. The review situates …

Plan To Fail By Failing To Plan: Deterring Prc Nuclear Force Expansion, Mark Tang, Grace Buettner

Space and Defense

This article argues that the United States must adapt its nuclear deterrence strategy to counter the People’s Republic of China’s (PRC) accelerating nuclear force expansion. As Beijing seeks to achieve nuclear parity with Washington—projecting up to 1,500 warheads by 2035—the authors contend that U.S. strategy must evolve from Cold War-era models to meet the Indo-Pacific’s unique strategic challenges. They propose the establishment of a Pacific Air Forces (PACAF) A-10 Strategic Deterrence and Nuclear Integration Division, modeled after its European counterpart, to enhance regional nuclear planning, integration, and allied assurance. The paper emphasizes the concept of escalation domination, arguing …

Earth’S Orbital Prison: Codifying Customary Law To Prevent Environmental Catastrophe In Space, Jacob Cook

Space and Defense

This article argues that the accelerating proliferation of space debris in low Earth orbit (LEO) poses an existential threat to the sustainability of the orbital environment—one comparable in strategic gravity to nuclear deterrence during the Cold War. Drawing on liberal internationalist theory and the concept of Mutually Assured Destruction (MAD), the paper asserts that deliberate satellite destruction through anti-satellite (ASAT) testing and negligent debris generation risk triggering a self-sustaining cascade of collisions known as the Kessler Syndrome. Existing treaties, including the Outer Space Treaty and the Artemis Accords, lack enforceable mechanisms to prevent such catastrophic harm. To fill this …

Enabling The Decisive Advantage, Mallory Stewart

Space and Defense

In her keynote address at the 2025 USSPACECOM Legal Conference, former Assistant Secretary of State Mallory Stewart argues that law, norms, and international cooperation are central to maintaining the United States’ “decisive advantage” in outer space. She emphasizes that rules and standards—far from constraining innovation or strategic flexibility—enhance predictability, reduce risk, and empower responsible competition. Stewart highlights the success of initiatives such as the Artemis Accords, the U.S. commitment to forgo destructive direct-ascent anti-satellite (ASAT) tests, and the global expansion of Space Situational Awareness (SSA) agreements as examples of how legal and normative frameworks reinforce stability and collaboration. She …

Space, Law, And National Security, Stephen Whiting

Space and Defense

In his address to the 2025 USSPACECOM Legal Conference, General Stephen Whiting underscores the indispensable role of legal professionals in shaping the future of military space operations and maintaining the rules-based international order in an increasingly contested domain. He outlines the rapid transformation of the space environment driven by commercial innovation, technological proliferation, and the accelerating threat landscape posed by adversaries such as China and Russia. The speech highlights U.S. Space Command’s three “moral responsibilities”: ensuring the delivery of space capabilities to the joint force and allies, protecting and defending critical space assets, and safeguarding the joint force from space-enabled …

Allied Abandonment And Nuclear Proliferation: Lessons From South Korea’S Secret Nuclear Program, Joseph W. Brown

Space and Defense

This article examines South Korea’s clandestine nuclear weapons program of the 1970s as a historical case study for understanding how perceptions of allied abandonment can drive nuclear proliferation. Drawing on alliance theory and archival evidence, the paper situates Seoul’s nuclear ambitions within the context of U.S. burden-shifting under the Nixon Doctrine, subsequent troop withdrawals, and diplomatic retrenchment across East Asia. Despite the continued U.S. military presence, South Korean leaders interpreted American rhetoric and policy actions as signaling a waning commitment to the alliance, prompting the initiation of a secret weapons program under President Park Chung-hee. The study identifies two enduring …

In Defense Of Space Offense, Alexander R. Kleitz

Space and Defense

This article argues that in the unique physical and operational environment of outer space, offensive operations hold intrinsic advantages over defensive ones. Drawing upon classical military theorists such as Clausewitz and Corbett, the author contends that the traditional dominance of the defensive form of war—rooted in terrestrial conditions—does not extend to celestial conflict. The transparency and remoteness of the space domain neutralize key defensive benefits, such as proximity to supply bases, concealment, and fortified positions, while also diminishing the factors that typically cause terrestrial offensives to culminate. Consequently, space conflict favors the side that seizes and maintains the initiative through …

Raising Public Awareness On Space Themes: Analysis Of Brazilian Space Policy Using Data From Google Trends, Andrea Felippe Cabello, Michele Melo

Space and Defense

This study examines whether Brazil’s national space policy goal of increasing public awareness of space activities has been met, using Google Trends data as a proxy for public interest. While public perception surveys are scarce outside the United States, web-based data provide a cost-effective and timely alternative for gauging public engagement. The authors analyzed two decades (2004–2024) of Brazilian search activity related to space topics, institutions, technologies, companies, and missions. Results show no clear upward trend in public interest, suggesting that Brazil’s stated policy objectives of raising awareness have not yet translated into measurable outcomes. Although searches related to government …

Costly Signals In Space: Increasing Credibility Via Strategic Disclosure, Wendy N. Whitman Cobb

Space and Defense

As space becomes an increasingly vital domain for national security, debates persist about how much secrecy should surround U.S. military space programs. This article argues that the strategic declassification and disclosure of selected space capabilities can strengthen U.S. deterrence by enhancing the credibility of deterrent threats. Drawing from theories of costly signaling and audience costs, the paper introduces strategic disclosure as a novel form of costly signal. Such disclosure imposes bureaucratic and operational costs while exposing capabilities to potential adversary countermeasures—thereby demonstrating resolve and seriousness of intent. In tandem, greater public transparency about space programs cultivates informed domestic audiences capable …

Space And Defense Vol. 16 No. 2 Editor's Note, Damon Coletta

Space and Defense

No abstract provided.

Space And Defense Vol. 16 No. 2 Table Of Contents, Editors Space And Defense

Space and Defense

No abstract provided.

Space And Defense Vol. 16 No. 2 Front Matter, Editors Space And Defense

Space and Defense

No abstract provided.

Space & Defense Volume 16 Issue 2 Fall 2025 (Whole Issue), Editors Space And Defense

Space and Defense

No abstract provided.

Localized Nuclear Utility For Erau Environmental Improvement, Timothy Schroeder, Jacob Blanton, Christopher Anderson

Sustainability Conference

The reliance of Embry Riddle Aeronautical University (ERAU) on energy supplied by Florida Power & Light (FPL), which currently draws large amounts of power from fossil fuel sources, is continuously suboptimal both environmentally and financially. This study proposes assessing the feasibility of deploying a campus scale nuclear reactor tailored to ERAU’s power consumption profile. This serves as a path toward reducing greenhouse gas emissions and limiting dependence on external fossil fuel generation. The methods used are primarily literature review(s), and numerical analysis on comparable use cases. The literature reviews focused on design theory and yield of nuclear reactors on a …

Investigating The Impact Of Forest Vegetation On Nuclear Weapon Prompt Radiation Energy Deposition, Paul A. Clement

Theses and Dissertations

This work seeks to answer the unstudied questions “Does a layer of vegetation impact the prompt radiation energy deposition in the soil from an atmospheric nuclear detonation?” and “If yes, by how much?” A new methodology was developed to repeatably automate and streamline a process of generating a three-dimensional geometry for subsequent radiation transport simulations and statistical analysis. The methodology streamlined three diverse applications: a three-dimensional mesh generator, a radiation transport simulation code, and a sensitivity analysis & uncertainty quantification software. The methodology was tested by simulating the quantitative influence that vegetation has on changing the energy deposition into the …

Defending Nato’S Northern Flank: Power Projecting And Military Operations, Nate Ostdiek

Space and Defense

This review evaluates Defending NATO’s Northern Flank: Power Projection and Military Operations, edited by Lon Strauss and Njord Wegge. The volume offers a comprehensive assessment of NATO’s evolving Arctic posture, combining doctrinal analysis, historical context, and alliance dynamics. Contributions examine Russia’s military strategy, U.S. Arctic policy, and intra-alliance complexities involving Denmark, Greenland, and the Faroe Islands. While the anthology provides valuable insights into NATO’s strategic challenges, it notably underrepresents Canada’s role. Overall, it stands as a timely and rigorous contribution to understanding Arctic security and NATO’s internal decision-making amid rising geopolitical competition.

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Modeling Nato Joint Warfighting Through Space Combat Simulations, Grant Nehls, Apoorva Somani

Space and Defense

This article investigates NATO’s dependence on space systems in joint warfighting and explores the use of simulation to quantify degradation effects. Using a custom-built AFSIM model of a NATO Arctic operation, the study demonstrates how GNSS spoofing and crosslink jamming undermine data integrity, commander trust, and strike execution—even without kinetic losses. Results show that partial degradations can cause mission failure through decision paralysis. By moving beyond binary modeling, this research highlights the need for nuanced simulations to prepare NATO for contested space environments and the challenges of great power competition.

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From The Last Frontier To The Final Frontier: The Polar Regions And Space Security, Michael Lynch

Space and Defense

This article examines the intersection of Arctic geopolitics and space security amid intensifying U.S., Russian, and Chinese competition. Melting ice has opened access to resources and new sea routes, elevating the Arctic’s strategic value while increasing reliance on space-based communications, navigation, and surveillance. Yet, vulnerabilities in polar orbits, aging ground infrastructure, and dual-use facilities expose critical systems to environmental hazards and geopolitical risks. The analysis highlights modernization efforts—including SHIELD and Golden Dome—as well as enduring cooperation and rivalries, underscoring the Arctic’s role as both a frontier of opportunity and a potential flashpoint in space-enabled security.

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Same But Different: The Survivability Of Arctic-Based Russian Second-Strike Capability, July Decarpentrie

Space and Defense

This article analyzes the survivability of Russia’s second-strike capability in the Arctic through the lens of classical nuclear deterrence theory. Despite heavy commitments in Ukraine, Moscow continues to modernize its Northern Fleet and reinforce bastion defenses, underscoring the Arctic’s role as the cornerstone of its retaliatory deterrent. While these strategies mirror Cold War practices, they face unprecedented challenges from NATO expansion, multipolar competition, and advances in anti-submarine detection technologies. The study concludes that safeguarding Russia’s second-strike capability not only shapes regional security dynamics but also has broader implications for global strategic stability.

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