Masters Theses

Abstract

"When a nuclear fuel is “burnt” in an atomic reactor it is not possible to completely utilize the fissionable material present due to build-up of fission products (which act as poisons), depletion of the fissionable material, and radiation damage to the fuel elements. Chemical processing of nuclear fuels is concerned with the recovery of the fissionable materials, specifically uranium, plutonium, and thorium, from the spent fuel elements. There are two general methods of reprocessing nuclear fuels: aqueous and non-aqueous. The aqueous methods include solvent extraction, ion exchange, and precipitation. Comprising the non-aqueous methods are fluoride volatility and pyrometallurgy. At the present time only the aqueous method is being used on a commercial scale by the Atomic Energy Commission in its reprocessing plants at Oak Ridge, Idaho Falls, Savannah River, and Hanford.

Of the aqueous processes for uranium purification, the most common is the liquid-liquid extraction of uranyl nitrate, by means of an organic solvent, from a uranyl nitrate-fission products solution. The uranyl nitrate is then re-extracted from the organic phase by water and is further processed-to the uranium oxides, uranium tetrafluoride, and finally to the uranium metal. If an enriched uranium is wanted, the tetrafluoride is converted to the hexafluoride which is processed by gaseous diffusion.

It is desirable that students in chemical and nuclear engineering have a sound theoretical and practical background in the chemistry and chemical engineering involved in the aqueous process. To support instruction in this field, a model of an aqueous nuclear fuels reprocessing plant was designed and constructed in the Unit Operations Laboratory of the University of Missouri School of Mines and Metallurgy. Since safety considerations ruled out the use of radioactive materials and/or heavy metals, the system water-methanol-trichloroethylene was chosen to represent the uranyl nitrate-organic solvent system employed in the actual process. In this case, methanol, representing the uranium, would be extracted from a solution of methanol-trichloroethylene by water, representing the organic solvent. The resulting mixture of methanol and water then would be separated by fractional distillation, representing the re-extraction and further purification steps.

The purpose of this investigation was to construct the necessary equipment to isolate, by fractional distillation (separation by differential vapor pressure), the products of a liquid-liquid extraction (separation by differential solubility) unit. The construction of the distillation unit was an integral part of and coordinated with the construction of the extraction equipment"--Introduction, pages 1-3.

Advisor(s)

Thompson, Dudley, 1913-1996

Committee Member(s)

James, William Joseph
Webb, William H.
Erkiletian, Dickran Hagop, Jr.

Department(s)

Chemical and Biochemical Engineering

Degree Name

M.S. in Chemical Engineering

Sponsor(s)

U. S. Atomic Energy Commission

Publisher

Missouri School of Mines and Metallurgy

Publication Date

1960

Pagination

viii, 116 pages

Note about bibliography

Includes bibliographical references (pages 102-112).

Rights

© 1960 Joseph Richard Aid, III, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Solvents -- Recycling -- Design
Distillation
Solvent wastes
Nuclear fuels

Thesis Number

T 1270

Print OCLC #

5928835

Electronic OCLC #

957780824

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