Date of Award

1-1-2011

Document Type

Campus Access Thesis

Department

Nuclear Engineering

First Advisor

Travis W Knight

Abstract

Research for Generation IV reactors has been performed and will likely continue for the next several decades. Research into advanced fuels is an important part of GenIV development. The coated particle fuel concept has been considered since the 1940s and the zirconium carbide layer of the advanced coated particle fuel has been considered to solve the specific problems such as overpressurization, kernel swelling, kernel migration, and/or attack of fission products since the 1970s. Thermochemical modeling can increase understanding of this advanced fuel. The modeling of binary systems and ternary systems of the nuclear fuel has been studied and published but there are not many literature articles for the thermodynamic and thermochemical research of the U-Zr-C-O system of advanced coated particle fuels. Therefore, this work focuses on thermodynamic and thermochemical modeling of a quaternary system of advanced coated particle fuels. Specifically, this research seeks to develop the experimental and analytical capabilities to study the U-Zr-C-O system. Modeling was done using, FactSage, a very powerful software for thermodynamics and thermochemistry simulations. In particular, thermodynamic modeling was performed to develop the Richardson-Ellingham diagram to evaluate the oxygen gettering ability of ZrC and SiC. It was further used to evaluate methods to control the oxygen partial pressure in experiments over a range of values representative of the TRISO fuel (10-8~10-6atm). This work was done in support of developing capabilities for future experimentation. Specifically, the mixing of CO/CO2 gases and the humidification of H2 or H2/Ar gas mixtures was evaluated. Experiments conducted as part of this effort utilized Ultra High Purity (UHP) Ar gas which was used to create an atmosphere with a very low oxygen pressure but without the ability to vary this over the entire range of interest. The experiments performed in this research utilized samples of Uranium Dioxide (UO2) and Uranium Dioxide (UO2) coated in a carbon seal coat followed by a zirconium carbide layer as an oxygen getter which would be representative of the advanced TRISO fuel kernel. For this research, techniques were developed using a Thermogravimetric Analyzer (TGA), which can very accurately monitor mass change of a sample as a function of temperature and time. It is also hoped that the methods used in this research will be utilized in order to model and analyze the properties of other advanced nuclear fuels.

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