Interatomic potentials for mixed oxide (MOX) nuclear fuels

TL;DR

This paper develops and validates new interatomic potentials for mixed oxide nuclear fuels, enabling accurate molecular dynamics simulations across various compositions and atomic collision energies.

Contribution

The authors extend existing potentials for UO₂ to (U,Pu,Np)O₂ by fitting to ab initio and experimental data, ensuring applicability across all interatomic distances without splining.

Findings

Potentials accurately reproduce ab initio and experimental results.

Applicable across all interatomic distances without splining.

Reliable for damage and molecular dynamics simulations in nuclear fuels.

Abstract

We extend our recently developed interatomic potentials for UO_{2} to the mixed oxide fuel system (U,Pu,Np)O_{2}. We do so by fitting against an extensive database of ab initio results as well as to experimental measurements. The applicability of these interactions to a variety of mixed environments beyond the fitting domain is also assessed. The employed formalism makes these potentials applicable across all interatomic distances without the need for any ambiguous splining to the well-established short-range Ziegler-Biersack-Littmark universal pair potential. We therefore expect these to be reliable potentials for carrying out damage simulations (and Molecular Dynamics simulations in general) in nuclear fuels of varying compositions for all relevant atomic collision energies.