Nuclear Engineering ETDs


Paul Sasa

Publication Date



Stringent licensing procedures for commercial nuclear reactor operation require an in-depth analysis of the phenomena associated with postulated reactor core overheating accidents. One aspect of nuclear reactor safety assessment is a prediction of fuel behavior associated with such postulated overheating events, which includes an assessment of the role of fission product inventory contained within irradiated fuel elements on fuel relocation potential. In general the gaseous fission product, such as Xenon and Krypton, have been considered the most likely candidates for fuel relocation due to gas dissolution from the fuel matrix and bubble expansion during fuel overheating; thus, such gaseous fission products have received considerable attention in fuel modeling efforts associated with accident code development work. However, the fissioning of UO2fuel in both a fast and slow neutron spectrum also results in the generation of a significant quantity of metallic fission products such as Barium, Iron, Molybdenum, and other metallic species. Metallurgical analysis of irradiated fuel indicates that such metals aggregate into inclusions found throughout the fuel matrix. During normal reactor operation such metallic inclusions are in a solid state, but at the elevated temperatures expected for overheating accident transients, such inclusions may tend to volatilize, contributing to fuel motion. This work involves an assessment of the potential effect of such metallic fission product inclusions to fuel motion for accident analysis and is the first known attempt at such an assessment.

Document Type




Degree Name

Nuclear Engineering

Level of Degree


Department Name

Nuclear Engineering

First Committee Member (Chair)

August William Cronenberg

Second Committee Member

Jay E. Boudreau

Third Committee Member

H. Eric Nuttall Jr.

Fourth Committee Member

Michael M. Stevenson

Fifth Committee Member

Ronald Allen Knief