Award Date

May 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Biochemistry

First Committee Member

Kenneth Czerwinski

Second Committee Member

James Vollmer

Third Committee Member

Daniel Koury

Fourth Committee Member

Alexander Barzilov

Number of Pages

221

Abstract

Next generation fast reactor designs utilizing metallic fuel are being developed as an alternative fuel cycle option in an effort to reduce carbon emissions. Historically, oxide fuels have been the industry standard, but interest in metallic fuel systems has grown considerably due to their thermal conductivity, fissile atom density, inherent safety, and ability to reach progressively higher burnups. Chemical complexity of metallic fuel systems increase as a function of burnup from fission product ingrowth and associated fuel cladding chemical interactions (FCCI) brought on by elemental redistribution and phase formation. To date, the most extensive operational study for metallic fuel was performed at the Experimental Breeder Reactor II (EBR-II) in Idaho from the 1960’s to the early 1990’s. During its operation, thousands of U-Zr and U-Pu-Zr fuel pins with various ranges of composition, burnup, and FCCI were analyzed from post-irradiated examinations (PIE) of spent fuel. Since decommissioning EBR-II, metallic fuel chemistry and fuel cladding studies for next generation reactors have become limited due to the lack of fast neutron irradiation facilities and data to support future designs. For this purpose, an arc melting procedure was developed for surrogate U-Zr and U-Pu-Zr burnup alloys with various fission product concentrations dependent on burnup. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) were used for qualitative and quantitative compositional analysis. Combined Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were used to determine thermal properties and phase transition temperatures. As cast alloys were implemented into diffusion couples with cladding components to determine FCCI. Targeted research aims to reach ultra-high burnups, where effects of increased burnup on fuel chemistry and FCCI must be understood to prevent eutectic formation and cladding breakdown. Data compiled in this work is compared to EBR-II for validation. Resulting data can be extrapolated to elevated burnups, yet to be studied experimentally, without the need of post-irradiated materials, thus increasing the knowledgebase to support next generation fast reactor development.

Keywords

Burnup; Metallic Fuel; Nuclear; Radiochemistry

Disciplines

Chemistry | Radiochemistry

Language

English

Available for download on Friday, May 15, 2020


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