Nuclear Engineering Commons^™

Understanding The Behavior Of Upper Subcritical Limit Calculations, Bobbi Riedel

Nuclear Engineering ETDs

This research consists of two comparison studies: the first study employed standard practices to characterize Upper Subcritical Limit (USL) estimation methods. A series of 33 neutronic systems that used standardized nuclear data and benchmark libraries were studied to compare the Whisper, TSURFER, and USLSTATS methods relative to a stochastic USL. USLs were also estimated for these 20 systems using the Whisper 1.1 code. Sensitivity data files were produced using MCNP6.2 and then used with the ORNL TSURFER and USLSTATS methods to estimate USLs for a cross-method USL comparison. The results show that USLs for each of the loosely coupled system …

Time-Of-Flight And Energy Loss Analysis On The Unm Fission Fragment Spectrometer, Shelby Fellows

Nuclear Engineering ETDs

The University of New Mexico spectrometer experimental work has been used to provide an event-by-event fission product measurement to aid in filling in the gaps in existing fission product yield data, as part of the Los Alamos National Lab Spectrometer for Ion Detection in Fission Research project (SPIDER) collaboration. This thesis examines the time-of-flight (TOF) component of the spectrometer towards improving the resolution of the system. Different thicknesses of TOF conversion foils were examined with alpha particles and fission fragments: 20, 55, and 100 µg/cm² carbon foils. For the thinnest carbon foil studied, a timing resolution of 160 ps …

Impact Of Fuel Rod Coatings On Reactor Performance And Safety, Ian Robert Stewart

Masters Theses

This study evaluates the use of a ceramic coating on the Zr-alloy cladding within a PWR using four ceramic compounds of 5 and 10 micron thicknesses: ZrO2, TiAlN, Ti2AlC, and Ti3AlC2. The film’s impact is assessed for variation on: reactivity, fuel cycle length, maximum temperature, film’s roughness, and transient conditions. The reactivity is analyzed using the following methods: change in the multiplication factor (k) each film introduces to the system using the ABH method, and Monte Carlo software (MCNP). Both methods are in good agreement, yielding less than half a percent change from a reference, no-film fuel pin. In order …

Improvement Of Spent Fuel Storage With Advanced Mechanical Shielding Placement, Gordon M. Petersen, Nicole Galante, Hannah Hale, Dylan Richardson, Robert Vance

Chancellor’s Honors Program Projects

No abstract provided.

Modified Sodium Diuranate Process For The Recovery Of Uranium From Uranium Hexafluoride Transport Cylinder Wash Solution, Austin Dean Meredith

Theses and Dissertations

Uranium hexafluoride (UF₆) containment cylinders must be emptied and washed every five years in order to undergo recertification, according to ANSI standards. During the emptying of the UF₆ from the cylinders, a thin residue, or heel, of UF₆ is left behind. This heel must be removed in order for recertification to take place.

To remove it, the inside of the containment cylinder is washed with acid and the resulting solution generally contains three or four kilograms of uranium. Thus, before the liquid solution can be disposed of, the uranium must be separated. A modified sodium diuranate …

Advanced Fuels Modeling: Evaluating The Steady-State Performance Of Carbide Fuel In Helium-Cooled Reactors Using Frapcon 3.4, Luke H. Hallman

Theses and Dissertations

Uranium carbide (UC) has long been considered a potential alternative to uranium dioxide (UO2) fuel, especially in the context of Gen IV gas-cooled reactors. It has shown promise because of its high uranium density, good irradiation stability, and especially high thermal conductivity. Despite its many benefits, UC is known to swell at a rate twice that of UO2. However, the swelling phenomenon is not well understood, and we are limited to a weak empirical understanding of the swelling mechanism.

One suggested cladding for UC is silicon carbide (SiC), a ceramic that demonstrates a number of desirable properties. Among them are …