Thermodynamics of fission products in dispersion fuel designs – First-principles modeling of defect behavior in bulk and at interfaces
✍ Scribed by X.-Y. Liu; B.P. Uberuaga; P. Nerikar; C.R. Stanek; K.E. Sickafus
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 597 KB
- Volume
- 268
- Category
- Article
- ISSN
- 0168-583X
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✦ Synopsis
Density functional theory (DFT) calculations of fission product (Xe, Sr, and Cs) incorporation and segregation in alkaline earth metal oxides, HfO 2 and UO 2 oxides, and the MgO/(U, Hf, Ce)O 2 interfaces have been carried out. These calculations demonstrate that the fission product incorporation energies in MgO are higher than in HfO 2 . However, this trend is reversed or reduced for alkaline earth oxides with larger cation sizes. In the case of UO 2 , the calculations were performed using spin polarization and with a Hubbard U term characterizing the on-site Coulomb repulsion between the localized 5f electrons. The fission product solution energies in bulk UO 2 ± x have been calculated as a function of non-stoichiometry x, and were compared to that in MgO. The solution energies of fission products in MgO are substantially higher than in UO 2 ± x , except for the case of Sr in hypostoichiometric UO 2 . Due to size effects, the thermodynamic driving force of segregation for Xe and Cs from bulk MgO to the MgO/fluorite interface is strong. However, this driving force is comparatively weak for Sr.