Author ORCID Identifier
https://orcid.org/0009-0004-3820-2166
Defense Date
2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Mechanical and Nuclear Engineering
First Advisor
Jessika Rojas
Second Advisor
Supathorn Phongikaroon
Abstract
Advanced reactors and used nuclear fuel separation (i.e. pyroprocessing technology) utilize high temperature salt as a thermal storage medium as well as an ionic solution for electrochemical processes. The use of these aggressive molten chloride and fluoride mediums requires specific materials or additional system alterations to extend the lifetime and structural integrity of equipment due to corrosion. Some materials, in the presence of inherently impure salt, will corrode and form oxide films in a specific formation that decreases corrosion rate by electrochemically and physically preventing elemental movement to the material surface. This is referred to as a passivation layer. However, this naturally forming passivation layer tends toward two flaws: 1) a spatially incomplete layer with imperfections that are prone to localized pitting and 2) for aluminum oxide or alumina-forming alloys specifically, the initial layer made of metastable alumina phases at molten salt temperatures is prone to lower density and therefore shows a smaller change in corrosion mitigation as compared to denser phase layers. By facilitating the pre-passivation of both alumina-forming alloys and approved molten salt structural material, this work proves the marked decrease in molten salt corrosion through forced high-density oxide layering via the use of laser ablation. Laser-Induced breakdown spectroscopy (LIBS) has been simultaneously used as a method of metal ablation as well as an initial verification tool for the successful application of the aforementioned passivation layer. This change in corrosion mitigation has then been verified via electrochemical testing, to include corrosion rate calculation and impedance-based film analysis. Ultimately, a comparison of laser treatment options, LIBS spectra, and corrosion rate data is provided to verify this claim, with planned future work required to increase the treatment viability as well as potential use cases for related work.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
12-12-2025