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Title Atomistic simulations of intrinsic and extrinsic point defects in uranium
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Publication Date
Date Accessioned
Degree MS
Discipline/Department Mechanical Engineering
Degree Level masters
University/Publisher Georgia Tech
Abstract Uranium (U) exhibits a high temperature body-centered cubic (b.c.c.) 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. Two separate generalized gradient approximations of the exchange-correlation are used to calculate defect properties and are compared. The bulk modulus, the lattice constant, and the Birch-Murnaghan equation of state for the defect free b.c.c. 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. The results for vacancies agree very well with experimental and previous computational studies. The most probable self-interstitial site in γ-U is the <110> dumbbell and the most probable defect location for dilute Zr in γ-U is the substitutional site. The most likely position for Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed.
Subjects/Keywords Fission gases; Point defects; First principles; Uranium; Uranium Defects; Computer simulation; Deformations (Mechanics)
Contributors Bojan Petrovic (Committee Member); Chaitanya Deo (Committee Member); Ting Zhu (Committee Member)
Country of Publication us
Record ID handle:1853/42833
Repository gatech
Date Indexed 2018-01-11
Issued Date 2011-11-02 00:00:00
Note [degree] MS; [advisor] Committee Member: Bojan Petrovic; Committee Member: Chaitanya Deo; Committee Member: Ting Zhu;

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