Tritium Diffusion Pathways in γ-LiAlO 2 Pellets Used in TPBAR: A First-Principles Density Functional Theory Investigation
- National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
With superior thermophysical and thermochemical properties, γ-LiAlO2 has high compatibility with other blanket materials and is used in the form of an annular pellet in tritium-producing burnable absorber rods (TPBARs) to produce tritium by thermal neutron irradiation of 6Li. In radiation damaged γ-LiAlO2, different types of vacancies, defects of its constituent elements, and other trapping sites hinder the diffusion process of tritium. In this study, the first-principles density functional theory approach is used to study the diffusion mechanisms of tritium defect and its species, such as interstitial and substitutional tritium defects, oxygen–tritium vacancy defects, and interaction of tritium with oxygen vacancies in defective and nondefective γ-LiAlO2. The obtained results provide an understanding of how such defects hamper the diffusivity and solubility of tritium. By calculating several different diffusion pathways, our results show that the smallest activation energy barrier is 0.63 eV for substitutional tritium diffusion with a diffusion coefficient of 3.25 × 10–12 m2/s. The smallest oxygen–tritium diffusion barrier is found to be 2.17 eV, which is around 3.5 times higher than the tritium diffusion barrier alone.
- Research Organization:
- National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Office of Fossil Energy (FE)
- OSTI ID:
- 1461484
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 122, Issue 18; ISSN 1932-7447
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Atomistic Simulations of the Defect Chemistry and Self-Diffusion of Li-ion in LiAlO2
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journal | July 2019 |
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