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Author
Title Atomistic investigations of uranium
URL
Publication Date
Date Accessioned
Degree PhD
Discipline/Department Mechanical Engineering
Degree Level doctoral
University/Publisher Georgia Tech
Abstract Uranium (U) exhibits a high temperature body-centered cubic (bcc) allotrope that is often stabilized by alloying with transition metals such as Zr, Mo, and Nb for technological applications. One such application involves U–Zr as nuclear fuel, where radiation damage and diffusion (processes heavily dependent on point defects) are of vital importance. Metallic nuclear fuels swell under fission conditions, creating fission product gases such as helium, xenon and krypton. Several systems of U are examined within a density functional theory framework utilizing projector augmented wave pseudopotentials. The bulk modulus, the lattice constant, and the Birch–Murnaghan equation of state for the defect free bcc uranium allotrope are calculated. Defect parameters calculated include energies of formation of vacancies in the α and γ allotropes, as well as self-interstitials, Zr, He, Xe and Kr interstitial and substitutional defects. This work is utilized in the construction of modified Embedded-Atom Method interatomic potentials for the bcc phase of uranium as well as the binary systems of U-Xe, U-Kr and U-He. Using this potential, equilibrium volume and elastic constants are calculated at 0 K and found to be in close agreement with previous first principles calculations. Further, the melting point, heat capacity, enthalpy of fusion, thermal expansion and volume change upon melting are calculated and found to be in reasonable agreement with experiment. Calculations of dilute fission gas defects show reasonable agreement with first principles calculations. Finally, void and xenon bubble energetics are analyzed as a function of temperature.
Subjects/Keywords Uranium; Alloys; Modified embedded-atom method; Nuclear fuels; Uranium as fuel; Fission gases; Nuclear fuels Breeding
Contributors Deo, Chaitainha (advisor); Zhu, Ting (committee member); Petrovic, Bojan (committee member); Garmestani, Hamid (committee member); Li, Mo (committee member)
Language en
Country of Publication us
Record ID handle:1853/49055
Repository gatech
Date Indexed 2018-01-11
Issued Date 2013-06-10 00:00:00
Note [degree] Ph.D.;

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