Nuclear Engineering ETDs

Publication Date

12-2018

Abstract

This research investigated the electrochemical deposition behavior of plutonium (Pu) and curium (Cm) for safeguarding the electrorefiner (ER) in a pyroprocessing facility. The main goal of this investigation was to evaluate the feasibility of using a safeguards concept called the neutron balance method to account for Pu in the ER. The neutron balance method relies on a known Pu/Cm ratio and measures neutrons from Cm-244 coming into and leaving a unit operation to track Pu. The application of the neutron balance approach for pyroprocessing facilities requires that Pu and Cm remain together in all extraction, product recovery, and waste streams. The electrochemical deposition experiments conducted, using a surrogate system of Tb and Gd, revealed that the Tb to Gd ratio was inconsistent between the electrolyte and the cathode deposit under different electrolyte concentrations. The Enhanced REFIN with Anodic Dissolution (ERAD) computer simulations of the same Tb/Gd surrogate system also found that the Tb to Gd ratio varied. ERAD simulations of a large-scale pilot facility also revealed that the Pu to Cm ratio was not constant between the electrolyte salt and the metal deposit when Pu co-deposition occurs. The safeguards assessment concluded that the neutron balance method was an insufficient safeguards approach for the eletrorefiner and working under the assumption that the Pu/Cm ratio was invariable resulted in the loss of significant quantities of special nuclear material (SNM) after processing only a few batches.

Keywords

reprocessing, electrochemistry

Document Type

Dissertation

Language

English

Degree Name

Nuclear Engineering

Level of Degree

Doctoral

Department Name

Nuclear Engineering

First Committee Member (Chair)

Cassiano Endres De Oliveira

Second Committee Member

Adam Hecht

Third Committee Member

Edward Blandford

Fourth Committee Member

Edward Arthur

Fifth Committee Member

Michael Simpson

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