Development of an interatomic potential for the study of the thermodynamic properties of oxide coumpounds containing americium

Sammanfattning: For the purpose of americium recycling, the effect of americium content on the nuclear fuel behaviour needs to be investigated. Atomic scale simulations and classical molecular dynamic simulations provide a tool of choice for the study of thermophysical properties of the nuclear fuel. In this work, we fitted a new interatomic empirical potential for (U,Am)O2 based on the CRG formalism. Our work enabled us to propose at the same time a new potential for the study of the Am-O system. The proposed potentials show good agreement with lattice parameters and enthalpy increments. We finally computed the heat capacity of (U,Am)O2 from 350 K to 3200 K for 0, 10, 20, 30, 40 and 50% americium contents using the potential obtained. The heat capacities calculated reveal a Bredig transition, as seen in UO2 and (U,Pu)O2. This transition shifts toward lower temperatures and its peak decreases in intensity when the Am content increases.