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), ErxYyMzZr1−x−y−zO2−(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 Er0.05Y0.10Ce0.10Zr0.75O1.925 and Er0.05Y0.10Pu0.10Zr0.75O1.925. 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.