Date of Award

Fall 2019

Document Type

Open Access Thesis

Department

Nuclear Engineering

First Advisor

Travis W. Knight

Abstract

Accident Tolerant Fuels (ATF) require a combination of fuel and cladding which have comparable longevity characteristics to UO2 while improving resistance to radiological release during and after accidents. U3Si2 has been proposed for use in ATF concepts for its high uranium density and high thermal conductivity which provide improved fuel performance. However, some of U3Si2’s material properties are not well understood. One such property, thermal creep of U3Si2, is an important contributing factor to U3Si2’s viability as an ATF. No experimentally derived thermal creep model is published for U3Si2, and previous analyses of compressive thermal creep experimental data lack statistical means of controlling for variability in the original data. This work uses previous compressive creep testing at the University of South Carolina to meticulously document the development of a thermal creep model for U3Si2 and implement that model in a BISON finite element simulation of a U3Si2 fuel SiC clad concept ATF. Rigorous statistical processes are used to ensure data are reproducible and reliable for use in the developed thermal creep model. This concept ATF shows significant delay to fuel-cladding contact when compared to traditional fuels of equal radial geometry and operational history. Sensitivity studies on fuel thermal creep rate, cladding thermal conductivity, cladding irradiation creep, cladding gap size, and cladding thickness demonstrate that research priorities for this concept ATF should revolve around reducing cladding thickness and improving U3Si2 plasticity.

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