Engineering Commons^™

A Numerical Study Of High Temperature And High Velocity Gaseous Hydrogen Flow In A Cooling Channel Of A Ntr Core, Sajan B. Singh

University of New Orleans Theses and Dissertations

Two mathematical models (a one and a three-dimensional) were adopted to study, numerically, the thermal hydrodynamic behavior of flow inside a single cooling channel of a Nuclear Thermal Rocket (NTR) engine. The first model assumes the flow in the cooling channel to be one-dimensional, unsteady, compressible, turbulent, and subsonic. The working fluid (GH₂) is assumed to be compressible. The governing equations of the 1-D model are discretized using a second order accurate finite difference scheme. Also, a commercial CFD code is used to study the same problem. Numerical experiments, using both codes, simulated the flow and heat transfer …

Two-Equation Two-Fluid Model For Bubbly Flow In A Vertical Channel, Jeffrey Feliszak, Martin Bertodano

The Summer Undergraduate Research Fellowship (SURF) Symposium

The one-dimensional two-fluid model is widely acknowledged as the most detailed and accurate macroscopic formulation of the thermo-fluid dynamics in nuclear reactor safety analysis. Several thermo-fluid dynamics codes have sprung up based on the one dimensional two-fluid model, such as RELAP5, TRAC, RETRAN, CATHARE, etc. However, these codes are quasi-steady because they lack the short wavelength models that are necessary to make the models well-posed; therefore they must rely on excessive numerical viscosity. Not utilizing short wavelength models causes small wavelength waves to grow quickly to infinity. The project objective is to develop a drafting force model for a one …

Compression Testing And Failure Modes Of Steel-Concrete Composite (Sc) Structures For Nuclear Containment, Patrick Michael Wanamaker, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Although being able to provide much cleaner power than burning coal and other fossil fuels, nuclear power plants are still a tough sell to the general public due to their history of being spontaneously dangerous. The containment structures surrounding these nuclear plants, however, can play a huge role in reducing the risks associated with them. Relatively new designs for these containment assemblies, known as SC (steel-concrete composite) structures, aim to increase the strength and durability of the containment facilities while keeping costs down. By varying the spacing between shear studs, the ratio of concrete to steel, and the ratio of …

Micrometeoroid Fluence Variation In Critical Orbits Due To Asteroid Disruption, Eliot Dan Aretskin-Hariton

Master's Theses

Micrometeoroids and orbital debris (MMOD) is a growing issue with international importance. Micrometeoroids are naturally occurring fragments of rock and dusk that exist throughout the solar system. Orbital debris is human made material like rocket bodies, paint flakes, and the effluent of spacecraft collisions. Even small MMOD particles on the order of 1 cm in diameter have the potential to destroy critical spacecraft systems. Because of this, MMOD is a threat to all spacecraft in orbit. Even governments that most sternly oppose US international policy have a stake when it comes to minimizing MMOD flux. Space-based assets are essential to …

Sensitivity And Uncertainty Analysis Of A Fixed Source Criticality Accident Alarm System Benchmark Experiment, Kevin Howard Reynolds

Doctoral Dissertations

The Department of Energy (DOE) Nuclear Criticality Safety Program (NCSP) funded the development of a criticality accident alarm system (CAAS) benchmark to be published by the International Criticality Safety Benchmark Evaluation Project (ICSBEP) in the International Handbook of Evaluated Criticality Safety Benchmark Experiments (handbook). While there are shielding related benchmark evaluations published in the handbook, the effort in this dissertation concerns a first of its kind experiment that has been conceived from the ground up as a pulsed critical fixed source benchmark.

The experiment was designed in conjunction with the French government and conducted at their SILENE reactor facility at …

Simulations Of Ti-Y-O Nanoclusters In Ferritic Alloys, Natalie Browning Camilli

Masters Theses

Nanostructured ferritic alloys possess high strength and resistance to radiation effects due to the presence of nanoprecipitates. Though nanostructured ferritic alloys have desirable mechanical properties, the exact composition and structure of the nanoprecipitates is unknown; thus, atomistic simulations involving the formation of nanoclusters give insight as to their structure. This thesis focuses on the structure, formation and radiation stability of Ti-Y-O [titanium-yttrium-oxygen] nanoclusters in iron. The activation energies for diffusion and the diffusion coefficients of oxygen interstitial atoms in iron are determined. The binding energies of various combinations of oxygen interstitial atoms and iron vacancies are also tabulated. Thermodynamic formation …

Offensive Cyber: Superiority Or Stuck In Legal Hurdles?, Jan Kallberg

Jan Kallberg

In recent years, offensive cyber operations have attracted significant interest from the non-Defense Department academic legal community, prompting numerous articles seeking to create a legal theory for cyber conflicts. Naturally, cyber operations should be used in an ethical way, but the hurdles generated by the legal community are staggering. At a time when the United States has already lost an estimated $4 trillion in intellectual property as a result of foreign cyber espionage, not to mention the loss of military advantage, focusing on what the United States cannot do in cyberspace only hinders efforts to defend the country from future …

Europe In A ‘Nato Light’ World - Building Affordable And Credible Defense For The Eu, Jan Kallberg, Adam Lowther

Jan Kallberg

From an outsider’s perspective, the Common Security and Defense Policy and the efforts of the European Defense Agency are insufficient to provide Europe with the defense it will require in coming decades. While the European Union—particularly the members of the European Monetary Union—struggle to solve prolonged fiscal challenges, viable European security alternatives to an American-dominated security architecture are conspicuously absent from the documents and discussions that are coming from the European Council and at a time when the United States is engaged in an Asia-Pacific pivot. This is not to say that no thought has been given to defense issues. …