Zirconium alloys have observed extensive use as cladding materials in nuclear applications due to their low thermal neutron absorption coefficient; the benefit of neutron economy, however, is offset by considerable performance issues such as breakaway irradiation growth at high fluences. This volume conservative distortion of cladding tubes can result in severe bowing and restricted coolant channels that adversely impact reactor reliability and performance. It is now known that the onset of the breakaway stage of irradiation growth coincides with the nucleation and growth of faulted vacancy loops (<c> loops) in the basal planes of zirconium’s hcp crystal structure. My research aims to elucidate the underlying mechanisms and factors that stabilize faulted <c> loop nucleation and growth to improve predictive capabilities of cladding tube deformation under irradiation. Current work includes utilizing Density Functional Theory (DFT) to study the impact that hydrogen and iron have on the stacking fault energies of basal intrinsic, basal extrinsic, and prismatic stacking faults.
Email: jmarchri@vols.utk.edu