Molecular dynamics simulation of zirconia-based inert matrix fuel

The structure and thermal properties of the zirconia-based inert matrix fuel were evaluated by the molecular dynamics (MD) simulations. For the yttria-stabilized zirconia doped with erbia and ceria (or plutonia), Er _xY_yM_zZr_1-x-y-zO_2-(x+y)/2 (where M = Ce or Pu), the MD simulation have been performed using the Born-Mayer-Huggins interatomic potential. The lattice constant, pair-correlation function and oxygen coordination number were discussed in terms of content of tetravalent ion, Ce⁴⁺ or Pu⁴⁺. The vibration properties of constituent ions could be deduced from the phonon-level densities for Er _0.05Y_0.10Ce_0.10Zr_0.75O _1.925 and Er_0.05Y_0.10Pu_0.10Zr _0.75O_1.925. The constant-volume heat capacity was calculated based on the harmonic oscillation model, and the dilatation contribution was evaluated from thermal expansion and bulk modulus. The constant-pressure heat capacity thus obtained from MD simulation was comparable with that estimated by Neumann-Kopp rule.