Award Date

May 2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Biochemistry

First Committee Member

Ralf Sudowe

Second Committee Member

Frederic Poineau

Third Committee Member

Samundeeswari Balasekaran

Number of Pages

121

Abstract

A novel method for partitioning americium from curium has been developed using sodium bismuthate as both an oxidant and a separation medium. The presence of americium and curium in nuclear waste increases the heat load in geological repositories and leads to larger waste volumes. These elements are also the source of most of the long-term radiotoxicity of the waste. However, the heat load and long-term radiotoxicity contribution from americium is much greater than that from curium. The contribution of curium to the heat load and radiotoxicity of the waste is significant on the same time scale as longer-lived fission products (137Cs, 90Sr, etc.). The currently envisioned advanced fuel cycle includes recycling of americium into fast reactor fuel, thus reducing the long-term radiotoxicity of the waste. The presence of curium in fuel would greatly complicate fuel fabrication and handling, making curium recycling undesirable. Efficient minor actinide separations are therefore an imperative capability for the development of advanced nuclear fuel cycles.

Methods for the partitioning of americium from curium are often complicated and time-consuming due to the similar chemical properties of these elements. A simple method for the isolation of americium from mixtures containing curium, as well as lanthanides and other fission product elements, could allow for the development of an efficient and economically feasible nuclear fuel-reprocessing scheme that would reduce the volume and hazardous lifetime of nuclear waste and increase fuel resource sustainability. This work demonstrates that sodium bismuthate chromatography is a promising method to address the challenge of isolating americium from curium, lanthanides, and fission product elements in a simple and cost-effective manner.

Keywords

Americium; Bismuthate; Curium; Radiochemistry; Separations

Disciplines

Chemistry | Radiochemistry

Language

English


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