Date of Award

8-2024

Document Type

Thesis

Degree Name

Master of Engineering (MEngr)

Department

Environmental Engineering and Earth Science

Committee Chair/Advisor

Timothy DeVol

Committee Member

Valery Bliznyuk

Committee Member

Nicole Martinez

Abstract

The extent of isotopic exchange of deuterium and tritium with protium atoms in hydrocarbon pump oil was investigated as a means to quantify the chemical stability of a mineral oil, a silicone oil, and a polyphenyl ether oil as candidates for implementation in a diffusion pump. In its target application at a fusion power plant, a chemically stable and radiation hard oil offers substantial reductions in tritium inventory, electrical consumption, and operational pump expenses over alternate solutions for vacuum induction. Select oils were introduced to deuterium and tritium isotopes in a high temperature environment, analogous to an operating vacuum pump. The resultant isotopic exchange was assessed using nuclear magnetic resonance in the measurement of deuterium, or liquid scintillation counting for the quantification of tritium exchange. In the first stage of the research, it was demonstrated that exchange of non-radioactive deuterium onto oil augments the radiation hardness and tritium exchange resistance of the oil in agreement with theory. The central experiment of the thesis evaluated isotopic exchange for the three test oils across nine different treatment scenarios that were conducted at a variety of temperatures, spanning from 170°C to 225°C, and ranged up to 14 days in length. Although the relative performances of the oils varied with treatment temperature, the mineral oil assumed the least tritium exchange at 225°C, which is the treatment scenario most consistent with the desired application at a fusion power reactor. Where other oils sustained specific activities on the order of thousands of becquerels per gram from their incorporation of radioactive tritium, the mineral oil had a specific activity of only 69 Bq/g after a 14-day tritium exchange treatment. In accounting for this drastic difference in isotope exchange between the oils, factors such as physical form of tritium, oil oxidation, and chemical structure were examined.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.